Mobile Communication and Mobile Computing Prof. Dr. Alexander Schill TU Dresden, Computer Networks Dept. http://www.rn.inf.tu-dresden.de

Contents 1. Motivation 2. Mobile Communication History Principles Media Access Methods Mobile Radio Networks: Overview GSM HSCSD, GPRS UMTS

Contents 2. Mobile Communication (Continuation) Broadband-Radio Systems Wireless Local-area Networks (IEEE 802.11, Bluetooth etc.) Satellite-based Systems

Contents 3. Mobile Computing Layer 3 Layer 4 MobileIP v4 & v6 DHCP Layer 4 Higher Layers and Services WAP, XML Mobile RPC CODA, Databases Mobile Agents Middleware for spontaneous networking Services and system support for Mobile Computing

Literature Roth, J.: Mobile Computing, dpunkt-Verlag, 2002 Very good overview to mobile communication and mobile computing Schiller, J., Mobilkommunikation, Techniken für das allgegenwärtige Internet, Addison-Wesley, 2000 Mobile Communication principles and Mobile Computing Bernhard, Walke: Mobilfunknetze und ihre Protokolle, 2 Bände. Teubner, 2000 Principles, GSM, UMTS and other cellular Mobile Radio Networks [Vol.1] Circuit Switched Radio, Cordless Phone Systems, W-ATM, HIPERLAN, Satellite Radio, UPT [Vol.2] Schumny, Harald: Signalübertragung, Friedrich Vieweg & Sohn, Braunschweig/Wiesbaden 1987; Wave propagation and wireless transmission A.S. Tanenbaum: Computernetzwerke, 4. Aufl., Prentice Hall, 1998 Protocols, ISO/OSI, standards, fixed networks Principles

1. Motivation and Examples

Motivation Ä New application areas, flexibility, improved workflows Speech- and Data Communication location independent and mobile Ä New application areas, flexibility, improved workflows Requirements: - Mobile end-devices - Radio transmission - Localization and signalization/management - Standards - Application Concepts for mobile end-devices in distributed systems - Control of heterogeneous, dynamic infrastructures Mobile Computing

Application example: Civil Engineering, Field Service Drafts, urgent modification Large archives, Videoconferences ATM ISDN Building of enterprise A (main office) Building of enterprise A (branch office) Architect X.25 ISDN ATM Selected drafts, Videoconferences GSM GSM Construction supervisor Material data, status data, dates Building site Building of enterprise B

WAP-Example: Order processing Order book Status of bond transactions. Executed and deleted orders are indicated in the order book for some days more. Partial execution of some order is presented as one open and one executed partial order in the order book. Details to an order could be indicated via dial-up of correspondent Links.

Perspective: Mobile Multimedia Systems Local Resources, Error Protocols Client Product Data Maintenance technician LAN-Access Main office Caching Mobile Access - very different performance and charges: radio networks versus fixed networks Software-technical, automatic adaptation to concrete system environment Example: Access to picture data/compressed picture data/graphics/text

Application Structure Ethernet Ethernet Distributed Database DB E-Fax-Order Branch office Firm xDSL Application Resource Mobile Station Communication path GSM Ethernet Cache Management DB-Access Distributed Database Client X

Traffic Telematics Systems Content Provider Main Office Content Provider ATM Internet GSM, RDS/TMC, DAB ... GSM Beam Radio, ISDN GSM GSM Radio/Infrared DAB: Digital Audio Broadcast RDS/TMC: Radio Data System/ Traffic Message Channel Infrastructure

Mobile Communication Networks: Examples GSM (Global System for Mobile Communications): worldwide standard for digital, cellular Mobile Radio Networks UMTS (Universal Mobile Telecommunications System): European Standard for future digital Mobile Radio Networks AMPS (Advanced Mobile Phone System): analog Mobile Radio Networks in USA DECT (Digital Enhanced Cordless Telecommunications): European standard for cordless phones TETRA (Terrestrial Trunked Radio): European standard for circuit switched radio networks ERMES (European Radio Message System): European standard for radio paging systems (Pager) 802.11: International standard for Wireless Local Networks Bluetooth: wireless networking in close/local area Inmarsat: geostationary satellite systems Teledesic: planned satellite system on a non-geostationary orbit

Mobile Communication: Development D (GSM900) E (GSM1800) Mobile Phone Networks HSCSD EDGE GPRS Cordless Telephony CT2 DECT IMT2000/ UMTS Packet Networks Modacom Mobitex Circuit Switched Networks Tetra Satellite Networks Iridium/ Globalstar Inmarsat Radio-LAN Local Networks IEEE 802.11/ Hiperlan MBS IR-LAN 1990 1995 2000 2005

Used Acronyms CT2: Cordless Telephone 2. Generation HSCSD: High Speed Circuit Switched Data GPRS: General Packet Radio Service EDGE: Enhanced Data Rates for GSM Evolution IMT2000: International Mobile Telecommunications by the year 2000 MBS: Mobile Broadband System

2. Mobile Communication

Principles

Mobile Communication Tied to electro-magnetic radio transmission terrestrial orbital (satellite) broadcast radio beam radio equatorial orbit non-equatorial orbit cellular non-cellular Principles: Propagation and reception of electro-magnetic waves Modulation methods and their properties Multiplex methods Satellite orbits/Sight- and overlap areas

Cellular Networks: Principles Interference Zone R Channels 801-1600 Channels 1-800 5R 1 5 6 3 7 4 2 R 7-Cell-Cluster (repeat sample of the same radio-channels) Supply- (radius R) and interference areas (5 R)

Cellular Networks: Principles Cell structure: Example Reference cell Cell in the interference area of the reference cell Further cells, whose channel distribution should be known to the reference cell

Kinds of antennas: directional & sectored Energy is radiated in definite directions, for instance x-Direction So called main propagation directions, for instance Satellite Antennas Often also used in Mobile Radio Systems, such as GSM, for creation of sectored cells Seamless radio supply via partial/overlay of sectors x z y x Directional Antenna Sectored Antenna

Media Access Methods

Principles Multiplex Media Access Methods Multiple-shift usage of the medium without interference 4 multiplex methods: Space Time Frequency Code Media Access Methods controls user access to medium

SDMA (Space Division Multiple Access) based on SDM (Space Division Multiplexing, Space Multiplex) communication channel obtains definite Space for definite Time on the definite Frequency with definite Code Space Multiplex for instance in the Analog Phone Systems (for each participant one line) and for Broadcasting Stations Problem: secure distance (interferences) between transmitting stations is required (using one frequency) and by pure Space Multiplex each communication channel would require an own transmitting station Space Multiplex is only reasonable in combination with other multiplex methods SDMA for instance by base station dedication to an end-device via Media Access Methods or respectively by segmentation of a Mobile Radio Network to several areas

SDMA: Example k1 k2 k3 k4 k5 k6 s f1 SDMA finds selection s – secure distance

FDMA (Frequency Division Multiple Access) Based on FDM (Frequency Division Multiplexing, Frequency Multiplex) i.e. to transmission channels several frequencies are permanently assigned, for instance radio transmitting stations k1 k2 k3 k4 k5 k6 t f k1 k2 k3 k4 k5 k6 f1 f4 FDMA finds selection f2 f5 s f3 f6 s – secure distance

TDMA (Time Division Multiple Access) Based on TDM (Time Division Multiplexing, Time Multiplex) i.e. to transmission channels is the transmission medium is slot assigned for certain time, is often used in LANs Synchronization (timing, static or dynamic) between transmitting and receiving stations is required k1 k2 k3 k4 k5 k6 TDMA finds selection t f k1 k2 k3 k4 k5 k6 f1

Combination: FDMA and TDMA, for instance GSM GSM uses combination of FDMA and TDMA for better use of narrow resources the used band width for each carrier is 200 kHz f in MHz 960 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 downlink 25 MHz 935,2 915 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 200 kHz 45 MHz uplink 25 MHz 890,2 t

CDMA (Code Division Multiple Access) based on CDM (Code Division Multiplexing, Code multiplex) i.e. to transmission channels the definite Code is assigned, this can be on the same Frequency for the same Time transmitted derivates from military area via development of cost-efficient VLSI components via spread spectrum techniques a good communication security and tiny fault sensitivity but: exact synchronization is required, code of transmitting station must be known to receiving station, complex receivers for signal separation are required Noise should not be very high

CDMA k1 k2 k3 k4 k5 k6 f1 CDMA decoded

CDMA illustrated by example The Principle of CDMA can be good illustrated by the example of some party: communication partners stand closely to each other, each transmission station (Sender) is only so loud, that it does not interfere to neighbored groups transmission stations (Senders) use certain Codes (for instance, just other languages), they can be just separately received by other transmission stations receiving station (Listener) attunes to this language (Code), all other Senders are realizing this only as background noise if receiving station (Listener) cannot understand this language (Code), then it can just receive the data, but it cannot do anything with them if two communication partners would like to have some secure communication line, then they should simply use a secret language (Code) Potential Problems: security distance is too tiny: interferences (i.e. Polish und Czech)

CDMA-Example in the theory Sender A Sends Ad =1, Key Ak = 010011 (set: „0“= -1, „1“= +1) Transmit signal As =Ad *Ak = (-1, +1, -1, -1, +1, +1) Sender B sends Bd =0, Key Bk = 110101 (set: „0“= -1, „1“= +1) Transmit signal Bs =Bd *Bk = (-1, -1, +1, -1, +1, -1) Both signals superpose additively in air Faults are ignored here (noises etc.) C = As+ Bs =(-2,0,0,-2,+2,0) Receiver will listen to Sender A uses Key Ak bitwise (internal product) Ae = C * Ak =2 +0+0 +2 +2+0 = 6 Result is greater than 0, so sent bit was „1“ analog B Be = C * Bk =-2 +0 +0 -2 -2 +0 = -6, also „0“

Spread Spectrum Techniques Signal is spread by the Sender before the transmission (overblown) dP/df value corresponds with so called Power Density, Energy is constant (in the Figure: the filled areas) Objective: Increase of robustness against small band-width faults listening security: power density of spread-spectrum signals can be lower than that of background noise

Spread Spectrum Techniques small band-width faults are spread by de-spreading in receiving station band-pass deletes redundant frequency parts

Mobile Radio Networks: Overview

Development of Mobile Radio General technological development in mobile telephony Satellite Systems (LEO) UMTS HSCSD GPRS EDGE GSM Phase II+ Digital cellular Networks...1800 Mhz PCN GSM1800 Digital cellular Networks...900 Mhz GSM900 Prognoses Anal. cellular Networks...900 Mhz Anal. cellular Networks...450 Mhz Analog Networks...150Mhz before 1970 1970 1980 1990 2000 2005

Correspondent data rates Satellites (GEO) (GEO)

Participant quantities in Mobile Radio – world-wide November 2002: 1148 Mio. participants world-wide (1119 Mio. digital & 29 Mio analog) (Source: http://www.emc-database.com) 1... Europe: Western 4... Americas (thereof 15.4 Mio. analog) 2... Asia Pacific 5... USA/Canada (thereof 5.4 Mio. analog) 3... Middle East 6... Africa 7… Europe: Eastern

Frequency Assignment Circuit Switched Radio Mobile Phones Cordless Phones Wireless LANs TETRA NMT TETRA CT2 CT1+ GSM900 CT1+ GSM900 380-400 410-430 453-457 450-470 (nationally different) 500Mhz 864-868 885-887 890-915 930-932 935-960 1GHz 463-467 TFTS (Pager, aircraft phones) GSM1800 TFTS GSM1800 DECT UMTS 1670-1675 1710-1785 1800-1805 1805-1880 1880-1900 (1885-2025 2110-2200) WLAN IEEE 802.11a: 5,15-5,25; 5,25-5,35; 5,725-5,825 IEEE 802.11b Bluetooth HIPERLAN1 HIPERLAN2 HIPER-Link MHz 2400-2483 2402-2480 5176-5270 (ca.5200,5600) (ca.17000) 2412-2472 Notes: - 2,4 GHz license free, nationally different - () written : Prognoses! - today speech over license free frequencies up to 61Ghz -> interesting for high data rates HomeRF...(approx.2400) TFTS - Terrestrial Flight Telephone System

Broadcast/multicast networks several carrier frequencies but participant obtains carrier for short time only often in use by taxi- und logistics enterprises etc., each own separated frequency reaches can use the same frequency packs with FDM- and TDM- techniques, i.e. more efficient handling with narrow resource frequency spectrum improves transition to fixed network, speech- and data services not for public access very reliable, cost-efficient

TETRA (Terrestrial Trunked Radio) former name: Trans-European Trunked Radio frequencies: 380-390, 410-420 MHz Uplink; 390-400, 420-430 MHz Downlink bandwidth of each channel: 25 kHz 1991 started by ETSI replace of national networks like MODACOM, MOBITEX or COGNITO Services: Voice + Data (V+D)- Service: Speech and Data, channel-oriented, uni-, multi- and broadcast possible Packet Data Optimized (PDO)- Service: packet-oriented, improves connection-oriented or connectionless service, as well as point-to-point and point-to-multipoint communication carrier services with data rate up to 28,8 kbit/s unprotected; 9,6 kbit/s - protected

TETRA, advantages compared with GSM, UMTS confirmed and/or non-confirmed Group Call (however it’s already possible with GSM today: up to 16 participants) Group call listening is possible (so called “open-channel mode”) very reliable fast dialing: approx. 300 ms (so called “push to talk”), GSM: several seconds certain independence of infrastructure (so called “direct mode” between end-devices) cost-efficient, especially for limited user quantity, because of the „large“ cells x • 10 km also especially suitable for emergency teams (fire department, ambulance etc.)

Cordless Telephony - DECT (Digital Enhanced Cordless Telecommunications) frequency reach: 1880 - 1990 MHz other than GSM limited to short reaches (1km) in buildings particularly under 50m is not designed for use at high rates mobile phones with GSM and DECT are available in the market 120 full duplex channels TDD (Time Division Duplex) for directional separation with 10ms frame length frequency reach is divided into 10 carrier frequencies using FDMA each station 10mW averaged, max. 250mW of transmitting power, GSM – radio phones transmit at 1 to 2W, fixed car phones up to 8W

DECT – system architecture HDB PA PT FT Local Networks VDB PA PT D1 FT Global Networks Local Networks FT.. Fixed Radio Termination PT.. Portable Radio Termination PA... Portable Terminations HDB.. Home Data Base VDB.. Visitor Data Base

DECT - Multiplex Used Data Used Data Synchronization Signalization CRC (Speech) (Speech) CRC Secure marker 32 bit 48 bit 160 bit 8 bit 160 bit 8 bit 64 bit 0,417 ms DECT-timeslot structure Transmission reach of fixed part (downlink) Transmission reach of mobile part (uplink) carrier frequency 1: 1 2 3 4 5 6 .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12' carrier frequency 2: 1 2 3 4 5 6 .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12' 1728 . . . kHz carrier frequency 10: 1 2 3 4 5 6 .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12' Transmission principle of DECT-system Channel 1 Channel 2 . . . Channel 12 Channel 1’ Channel 2' . . . Channel 12' fixed part to mobile part mobile part to fixed part Time duplex with 10 ms frame length Structure of DECT-time multiplex frame

Pager systems: overview Eurosignal to each participant 4 different audio signals using 4 diverse call numbers are assigned. Meaning must be agreed. Receiving stations are at a size of a cigarette packet 85 senders in the 87 MHz-reach (ultra short waves) called person location must be approximately known: 3 area codes: North 0509, Middle 0279, South 0709 Cityruf (city call) additionally to 4 audio- or respectively optical signals transmission of short numerical (15 digitals) or alpha-numerical messages (80 characters) exists optionally, receiving station is smaller than with Eurosignal PEP (Pan European Paging) preparation for coupling of national services for ERMES D: Cityruf, F: Alphapage, GB: Europage, I: SIP ERMES (European Radio Message System) ETSI-Standard for pan-European radio service, similar to PEP but in 169 MHz-reach with 60 Mio. addresses

GSM: Global System for Mobile Communications

GSM: Properties cellular radio network (2nd Generation) digital transmission, data communication up to 9600 Bit/s Roaming (mobility between different net operators, international) good transmission quality (error detection and -correction) scalable (large number of participants possible) Security mechanisms (authentication, authorization, encryption) good resource use (frequency and time division multiplexing) integration within ISDN and fixed network standard (ETSI, European Telecommunications Standards Institute)

Providers in Germany (1) D1 T-Mobile subscribers: 24,6 Mio (Stand 2003) Vodafone D2 old name: Mannesmann Mobilfunk D2 subscribers: 22,7 Mio (Stand 2003) E-plus O2 old name: VIAG Interkom

Providers in Germany (2) Subscribers, millions 2001 2002 2003 World-wide by 2003 D1 T-Mobile 22,6 23,1 24,6 82 Vodafone D2 21,9 - 22,7 112,5 E-Plus 7,5 O2 VIAG Interkom 3,66

GSM: structure Fixed network Switching Subsystems Radio Subsystems OMC Data networks VLR HLR AuC EIR MS (G)MSC BSC BTS MS PSTN/ ISDN BTS Network Management Call Management BSS MS MS Mobile Station (G)MSC (Gateway) Mobile Switching Centre OMC Operation and Maintenance Centre PSTN Public Switched Telephone Network VLR Visitor Location Register ISDN Integrated Services Digital Network AuC Authentication Centre BSS Base Station Subsystem BSC Base Station Controller BTS Base Transceiver Station EIR Equipment Identity Register HLR Home Location Register

GSM: Structure Operation and Maintenance Centre (OMC) logical, central structure with HLR, AuC und EIR Authentication Centre (AuC) authentication, storage of symmetrical keys, generation of encryption keys Equipment Identity Register (EIR) storage of device attributes of allowed, faulty and jammed devices (white, grey, black list) Mobile Switching Centre (MSC) arrangement centre, partial as gateways to other nets, assigned to one VLR each Base Station Subsystem (BSS): technical radio centre Base Station Controller (BSC): control centre Base Transceiver Station (BTS): radio tower / antenna

Radio technical structure 1 TDMA-Frame, 144 Bit in 4,615 ms 8 TDMA-channels, together 271 kBit/s inclusive error protection information 124 radio frequency channels (carrier), each 200 kHz downlink 890 915 MHz uplink 935 960 MHz 2 frequency wavebands, for each 25 MHz, divided into radio cells One or several carrier frequencies per BSC Physical channels defined by number and position of time slots

GSM: protocols, incoming call (4) BSS (3) VLR HLR (8) (7) (6) (11) (10) (4) (2) (8) (8) PSTN/ ISDN (5) (1) (9) (9) MSC GMSC BSS BSS (12) (12) (8) BSS (1) Call from fixed network was switched via GMSC (2) GMSC finds out HLR from phone number and transmits need of conversation (3) HLR checks whether participant for a corresponding service is authorized and asks for MSRN at the responsible VLR (4) MSRN will be returned to GMSC, can now contact responsible MSC

GSM: protocols, incoming call (4) BSS (3) VLR HLR (8) (7) (6) (11) (10) (4) (2) (8) (8) PSTN/ ISDN (5) (1) (9) (9) MSC GMSC BSS BSS (12) (12) (8) BSS (5) GMSC transmits call to current MSC (6) ask for the state of the mobile station (7) Information whether end terminal is active (8) Call to all cells of the Location Area (LA) (9) Answer from end terminal (10 - 12) security check and connection construction

GSM: protocols, outgoing call VLR BSS MSC GMSC HLR (5) (3) (4) (2) (1) (1) Demand on connection (2) Transfer by BSS (3-4) Control for authorization (5) Switching of the call demand to fixed net

GSM: channel strucure Traffic Channel speech- / data channel (13 kbit/s brutto; differential encoding) units of 26 TDMA - Frames Half-rate traffic channel: for more efficient speech encoding with 7 kbit/s Control Channel Signal information Monitoring of the BSCs for reconnaissance of Handover Broadcast Control Channel BSC to MS (identity, frequency order etc.) Random Access Channel Steering of channel entry with Aloha-procedure Paging Channel signalize incoming calls

Databases Home Location Register (HLR), stores data of participants, which are reported in an HLR-area Semi-permanent data: Call number (Mobile Subscriber International ISDN Number) - MSISDN, e.g. +49/171/333 4444 (country, net, call number) identity (International Mobile Subscriber Identity) - IMSI: MCC = Mobile Country Code (262 for .de) + MNC = Mobile Network Code (01-D1, 02-Vodafone-D2, 03-eplus, 07-O2) + MSIN = Mobile Subscriber Identification Number Personal data (name, address, mode of payment) Service profile ( call transfer, Roaming-limits etc.) Temporary data: MSRN (Mobile Subscriber Roaming Number) (country, net, MSC) VLR-address, MSC-address Authentication Sets of AuC (RAND (128 Bit), SRES (128 Bit), KC (64Bit)) charge data

Databases Visitor Location Register (VLR) local database of each MSC with following data: IMSI, MSISDN service profile accounting information TMSI (Temporary Mobile Subscriber Identity) - pseudonym for data security MSRN LAI (Location Area Identity) MSC-address, HLR-address

GSM: mobile telephone areas MSC-area = VLR-area Handover radio-cell with BTS Location Area (LA) LA = smallest addressable unit

Connection HLR, VLR HLR MSC-area VLR Location area advantage of the architecture: Location Update at limited mobility, as a rule only at VLR, rarely at (perhaps far remote) HLR

Localization at GSM LA 3 LA 2 LA 5 LA 3 +49 0177-26 32311 VLR 10 VLR 9 IMSI LA 2 HLR 26 32311 z.B. 0x62F220 01E5 +49 0177-26 32311 LA 3 LA 2 participant call number in HLR country code number net-entry code Provider LA 5 LA 3

Data transmission each GSM-channel configurable as a data channel; similar structure like ISDN-B and -D-channels data rates up to 9600 bit/s now delay approximately 200 ms speech channels have as a rule higher priority as data channels kinds of channels: transparent (without error correction; however FEC; fixed data rate; error rate 10-3 up to 10-4) non-transparent (repeat of faulty data frames; very low error rate, but also less throughput) Short-Message-Service (SMS) connectionless transmission (up to 160 Byte) on signal channel Cell Broadcast (CB) connectionless transmission (up to 80 Byte) on signal channel to all participants, e.g. one cell

Data transmission - structure BSC MSC IWF ISDN UDI BTS Modem TA PSTN Internet Modem IWF - Inter Working Function UDI - Unspecified Digital TA - Terminal Adapter

Security aspects: Subscriber Identity Module (SIM) Chip-card (Smart Cart) to personalize a mobile subscriber (MS): IMSI (International Mobile Subscriber Identity) participant special symmetric key Ki, stored also at AuC algorithm “A3” for Challenge-Response-Authentication algorithm “A8” for key generation of Kc for content data PIN (Personal Identification Number) for entry control Temporary data: TMSI (Temporary Mobile Subscriber Identity) LAI (Location Area Identification) Encryption key Kc

Security in GSM-networks SIM Entry control and cryptographic algorithms Single-sided authentication (participant against network) Challenge-Response-method (cryptographic algorithm: A3) Pseudonyms of participants at the Radio interface Temporary Mobile Subscriber Identity (TMSI) Connection encoding on the Radio interface Key generation: A8 Encryption: A5

Security aspects: Authentication MS MSC, VLR, AuC max. 128 Bit Random number generator A3 Authentication Request RAND (128 Bit) A3 SRES Authentication Response = SRES (32 Bit) Location Registration Location Update with VLR-change Call setup (in both directions) SMS (Short Message Service)

Security aspects: Session Key MS Netz Random number generator Authentication Request A8 RAND (128 Bit) 64 Bit A8 Key generation: Algorithm A8 Stored on SIM and in AuC with Ki parametric one way function no (Europe, world wide) standard can be determined by net operator Interfaces are standardized combination A3/A8 known as COMP128

Security aspects: encryption at the Radio interface MS Net TDMA-frame- number Ciphering Mode Command TDMA-frame- number A5 A5 Key block Ciphering Mode Complete + + Plain text block Encrypted Text Plain text block 114 Bit Data encryption through algorithm A5: stored in the Mobile Station standardized in Europe and world wide weaker algorithm A5* or A5/2 for specific countries

GSM-Security: assessment cryptographic methods secret, so they are not „well examined“ symmetric procedure consequence: storage of user special secret keys with net operators required low key length Ki with max. 128 Bit (could be hacked by using Brute Force Attack in 8-12 hours) no mutual authentication intended consequence: Attacker can pretend a GSM-Net no end-to-end encryption no end-to-end authentication Key generation and -administration not controlled by the participants

GSM Phase II+ HSCSD, GPRS

HSCSD: High Speed Circuit Switched Data

Properties higher data rate because of channel bundling parallel usage of several time slots (TCH) of one frequency on Um more efficient channel encoding (14,4 kbit/s per TCH) Data rates from 9,6 up to 53,8 kbit/s asymmetric transmission (1TCH Uplink / 3TCH Downlink)

HSCSD data rates transparent non transparent 1 + 1 9,6 14,4 9,6 13,2 up- / downlink 100% coverage 95% coverage 100% coverage 95% coverage 1 + 1 9,6 14,4 9,6 13,2 2 + 2 19,2 28,8 19,2 26,4 1 + 3 --- ---- 28,8 39,6 1 + 4 --- ---- 38,4 53,8

HSCSD: structure ISDN PSTN Internet MSC BSC IWF UDI BTS Modem TA n time slots (TCH) of each TDMA frame (theoretically max. 8) PSTN Internet Modem IWF - Inter Working Function UDI - Unspecified Digital TA - Terminal Adapter

n time slots (TCH) of each TDMA frame HSCSD: changes n time slots (TCH) of each TDMA frame (theoretically max. 8) BTS BSC MSC Um Abis A multiplex of the time slots on each 64 kBit/s channel certain changes are necessary at the component several changes at the software/firmware minimal changes at the software/firmware

HSCSD radio interface Required time for setting to transmission standby Required time for setting to receiving standby 1 2 3 4 5 6 7 1 2 3 4 5 6 7 MS RECEIVE 5 6 7 1 2 3 4 5 6 7 1 2 3 4 MS TRANSMIT MS MONITOR Required time for signal strength measure and setting to receiving standby parallel usage of several time slots limited to one frequency Cost factor limits number of used TCH‘s to (2+2) or (1+3, uplink, downlink)

Assessment of HSCSD existing net structure and accounting model maintained in comparison to GPRS only around1/5 of investment necessary HSCSD is still circuit switched has defined QoS- settings (data rate, delay) one logical channel will be switched on all interfaces for the time of the connection Non-efficient for burst-like traffic (Internet) or Flat Rate billing (Logistics) no international acceptance (Roaming!) uses also more resources on the radio interface problems with handover into a new cell

GPRS: General Packet Radio Service

Properties Packet switching service (end- to- end) Data rates up to 171,2 kbit/s (theoretical) Effective and flexible administration of the radio interface adaptive channel encoding Internetworking with IP- and X.25 nets standardized dynamic sharing of resources with „classical“ GSM speech services Advantage: Billing and Accounting according to data volume Disadvantage: cost intensive additional net hardware necessary

Properties point-to-point-Packet transfer service PTP-CONS (PTP Connection oriented Network Service) connection oriented, similar to X.25 PTP- CLNS (PTP Connectionless Network Service) connectionless, similar to IP point- to- multipoint - group communication

GPRS Backbone Frame Relay / ATM GPRS: Structure GPRS Nets other operators GSM BSC MSC HLR BTS Internet Border Gateway SGSN GGSN other packet switching networks GGSN GPRS Backbone Frame Relay / ATM SGSN - Serving GPRS Support Node GGSN - Gateway GPRS Support Node signalization data user data

GPRS: Changes public remote fixed nets Um other packet switching GMSC public remote fixed nets n time slots (TCH) per TDMA frame (theoretically max. 8) per packet! Circuit switched traffic MSC MAP A Abis HLR/AuC GPRS register BTS BSC Gs PCU Gb MAP SGSN other packet switching networks Packet arranged traffic Um Gn Gi GGSN modified network components new components or extensively modified components Existing components PCU - Packet Control Unit

Tasks: SGSN, GGSN External Data Domain HLR Internet SGSN: - mobility management - session management - QoS - security HLR External Data Domain MAP Signalization (GGSN) MAP Signalization (SGSN) SGSN Intranet Internet BSS PCU GGSN BSS PCU Client SGSN BSS PCU SGSN, GGSN: - Routing - Signalization - Resource management Client Server

Tasks of the SGSN Packet delivery mobility management apply/ sign off of terminals localization LLC (Logical Link Control) management authentication billing

Tasks of the GGSN mediator between GPRS backbone and external data networks (Internet, X-25 etc.) converts GPRS packets, data Protocol (PDP) into the corresponding structure also converts PDP addresses of incoming packets into GSM address of the receiver saves current data for the SGSN address of the participant as well as their profile and data for authentication and invoice

GPRS: air interface Radio Link Control (RLC) Segmentation of the LLC-Frames in RLC blocks Block size dependent on short-term channel conditions Backward error correction and data flow control by Automatic Repeat Request (ARQ) protocol repeating not repairable RLC blocks selectively Medium Access Control ( MAC) Channel reservation contains: - one/several time slots (Packet Data Channels PDCH) of one frequency one uplink status flag (USF) per Packet Data Channel (PDCH), channel partition of up to 8 ms

GPRS: air interface Reservation in the uplink (MS to BSS): Medium Access Control ( MAC) Reservation in the uplink (MS to BSS): MS sends reservation request on a Random Access Channel (Slotted ALOHA) BTS allocates a (split) channel and sends packet assignment MS sends data depending on the current priority (USF flag) Reservation in the Downlink (BSS to MS): BTS displays transmitting request and informs about the reserved channel MS supervises the reserved channel and receives

GPRS: air interface Physical Link Control adaptive forward error correction (FEC) dependent on short-term channel conditions temporal scrambling (Interleaving) of the bursts and Mapping on reserved PDCH (Packet Data Channel) procedure to recognize overbooking situations on the physical channel GPRS Channel Encoding

Quality of Service QoS profile agrees service parameters inside the whole network Agreed for the duration of one PDP (Packet Data Protocol) context (session, end terminal is obtainable for the duration of the context, e.g. obtainable over Internet ) : temporary address (IP) for mobile station tunneling information, among others GGSN, which is used for access to corresponding packet arranged network type of the connection QoS profile QoS profile commits: precedence class, priority against other services (high, normal, low) packet delay class, times are valid for traffic inside the GPRS- network reliability class peak throughput class mean throughput class

Quality of Service Packet delay classes Security classes

Quality of Service GPRS- using data rates CS 3 and CS 4 are only reasonable in the second phase of GPRS introduction They will be used adaptively at corresponding good quality of radio connection CS 4 does not comprise error correction, code rate = 1!

Assessment of GPRS An up to 4 times higher data rate in comparison to ordinary GSM- data services better resource management through packet arranged service „always on” data service (email, etc.) GPRS is a more suitable carrier for services like WAP - IP-derivate, no true guaranties (QoS) - development of the network infrastructure is relatively expensive, particularly regarding introduction to UMTS (return of investment) - GPRS doesn’t give such data rates like advertising has sometimes promised

Development of the GSM-data services Data rate CS 1 CS 2 39.6 kbit/s 40.2 kbit/s 26.4 kbit/s Channel packing, NT HSCSD 27.2 kbit/s 26.8 kbit/s Packet arranged GPRS 18.1 kbit/s 13.2 kbit/s 13.4 kbit/s 9.6 kbit/s 9 kbit/s flow

Enhanced Services - EMS (enhanced message service) Uses widespread existing infrastructure (SMS) new Mobile telephones necessary allows sending and receiving of messages with formatted texts, melodies, graphics (32 x 32 Pixel) and animations (16 x 16 Pixel) – e.g. NOKIA new applications like Mobile Ticketing tickets will be transferred to mobile phone like a bar code and checked at the admission EMS enables transition to MMS (multimedia messaging service), which allows transmission of multimedia enriched messages over UMTS-Network (photos, parts of videos) MMS requires new network elements in the Infrastructure of the operators

MMS - architecture MMS User Databases HLR MMS Relay LDAP GSM-MAP or IS-41-MAP or TCP/IP WAP or MExE (e.g. Java and TCP/IP) MMS User Agent SMTP, HTTP, POP3, IMAPv4 SMTP alien MMS Relay . . . MMS Server (e.g. E-Mail) MMS Server (e.g. Fax) MMS Server (other service) Based on materials from 3GPP, http://www.3gpp.org

UMTS: Universal Mobile Telecommunications System, 3G, 3rd generation of mobile radio

IMT-2000 - structure 3 systems - UMTS - CDMA2000 - UWC-136 2 core technologies - TDMA - CDMA individual carrier IMT-SC UWC-136 (EDGE) TDMA multiple carrier IMT-FT DECT IMT-2000 IMT-DS UTRA-FDD FDD IMT-MC CDMA2000 CDMA IMT-2000 family of radio interfaces : IMT-DS (Direct Spread) UTRA-FDD (UMTS) IMT-MC (Multi Carrier) CDMA2000, USA IMT-TC (Time Code) UTRA-TDD (UMTS), TD- SCDMA (Synchronous Code Division Multiple Access, China) IMT-SC (Single Carrier) UWC-136, USA IMT-FT (Frequency time) DECT UTRA-TDD TDD IMT-TC TD-SCDMA satellite- supported network expansion: - SW-CDMA: Satellite Wideband CMDA - SW-CDTMA: Satellite Wideband CDMA/TDMA (Hybride procedure) - SAT-CDMA: Satellite CDMA - ICO RTT: ICO Radio Transmission Technology In europe UMTS ICO RTT... Standard by ICO Global Communications IMT ... International Mobile Telecommunications UTRA ... Universal Terrestrial Radio Access UWC ... Universal Wireless Communications source: www.UMTS-Report.com

Worldwide frequency assignment for IMT-200 developed by ITU PCS... Personal Communication System MSS...Mobile Satellite Service PHS... Personal Handy-Phone System

UMTS - Facts consideration: early 90ies Universal Mobile Telecommunications System, developed in the EU (ETSI: European Telecommunication Standards Institute) UMTS is the European implementation of IMT-2000 (International Mobile Telecommunications by the year 2000) Start of network expansion: in Europe: 2003 (some trials, e.g. British Telecom on Isle of Man, 2002) in the USA: 2005 in Japan since 2000 : NTT DOCOMO

Frequency award in Europe 230 MHz frequency range for IMT-2000 GSM1800 Uplink GSM1800 Downlink FDD Uplink MSS FDD Downlink MSS DECT TDD TDD 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 MSS…Satellite- based at FDD symmetrical spectrum is necessary, not at TDD (time slots at same frequency) gradual new assignment of wavebands depending on development of the need up to 300-500 MHz frequency range in 2008 source: www.UMTS-Report.com

Characteristics system general , worldwide roaming high data rates: 144 kbit/s mobile, up to 2 Mbit/s at local area fusion of different mobile radio communications-, wireless- and pager-systems into one common system speech-, data-, and multimedia- information services independent of used network access support of different carrier services: real-time capable/not real-time capable circuit switched/ packet switched Roaming also between UMTS and GSM and satellite networks Asymmetrical data rates in up-/downlink

UMTS- Disadvantages Technology not yet perfect rent ability of pico cells („Hotspots“) not yet analyzed strong contention by WLAN increased radiation exposure high data rate only obtainable sometimes (High-Tech-network expansion, stationary and exclusive usage necessary!) because of high license costs high charges necessary (around double GSM-costs)

UMTS - Performance Photo Report Video UMTS Web Photo Report Video GPRS Transmission Real- time (Video) Not Real-time (SMS etc.) Bit error rate 10-3 … 10-7 10-5 … 10-8 Permitted delay 20ms … 300ms > 150 ms Photo Report Video UMTS Web Photo Report Video GPRS Mail Web Photo Report Video ISDN Mail Web Photo PSTN Mail Web Photo Report Video GSM ~ 0 sec 10 sec 1 min 10 min 1 h source: Mobilkom Austria

UMTS - Hardware big color displays high resolution True Color

UMTS- cell structure UMTS-Core Network Internet customer Intranet BTS Home Location Register Gateway GPRS Support Node Gateway Mobile Switching Centre circuit switched customer Intranet PSTN/ ISDN 3G- Serving GPRS Support Node 3G Mobile Switching Centre Visitor Location Register packet- switched Base Station Controller Radio Network Controller Radio Network Controller BTS BTS BTS BTS BTS BTS BTS BTS BTS Radio access network GSM - BSS UTRAN- UMTS Terrestrial Radio Access Network Quelle: Mobilkom Austria

UMTS: cell structure “World cell” Satellite Zone 4: Global Zone 3: Suburban “Macro cell” Zone 2: Neighborhood Zone1: In-building “Micro cell” “Pico cell” Integration with the fixed network Basic terminal PDA terminal Audio/visual terminal

UMTS: hierarchical cell structure principle: - all neighbor cells use same frequency channel - only one waveband is necessary for cellular construction - further wavebands are necessary for hierarchical structure Global Regional Lokal Home/ Office Pico World Micro Macro expansion Data rate (kbit/s) Max. velocity (mph) Special features World Cell global - no UTRAN, other technology! Macro Cell Up to 1,24 miles 144 310 complete national UMTS support Micro Cell Up to 0,62 miles 384 74 Greater cities, commonly used Pico Cell > 60miles 2000 6,2! „Hotspots“ – e.g. airport, station

Classification

Service concept Virtual Home Environment (VHE): offered services are freely configurable, configuration still exists in the whole network choose of service quality and also arising costs behave at bottlenecks (data rates, etc.) configurable dynamic customization to connection

UPT: Universal Personal Telecommunication Service one phone number for several devices (Call- Management) subscriber localization e.g. with SIM-card call passing virtual mobility of fixed networks

Intelligent networks Implementation of basic services like subscriber localization billing etc. supply of value added service (Voice-Mailbox, etc.) possibility of easy, fast introduction of new services flexible service administration usage of services also from foreign network possible better control of service parameters through subscriber

UMTS: basic network structure Access Network: base stations, responsible for radio contact to mobile end devices Core Network (Fixed Network): responsible for structure of connections Intelligent Network (IN): responsible for billing, subscriber localization, Roaming, Handover Intelligent Network Core Network Access Network User Equipment (UE)

General reference architecture UE UTRAN Uu Iu CN UTRA: UMTS Terrestrial Radio Access UTRAN (UTRA- Network) contains several radio subsystems, so called Radio Network Subsystems (RNS) and contains functions for mobility management RNS controls handover at cell change, capacitates functions for the encoding and administrates the resources of the radio interface Uu connects UTRAN with mobile end devices, so called User Equipment (UE), is comparable with Um in GSM UTRAN is connected over Iu with the Core Network, comparable with the A interface in GSM between BSC and MSC CN contains the interfaces to other networks and mechanisms for connection handover to other systems

The UMTS-radio interface UTRA (UMTS Terrestrial Radio Access) Two modes defined: UTRA/FDD (Frequency Division Duplex) mainly in suburban areas for symmetrical transmission of speech and video data rates up to 384 kbit/s, supra-regional roaming for circuit- and packet switched services in urban areas UTRA/TDD (Time Division Duplex) mainly in households and other restricted areas (company's premises, similar to DECT) for broadcast of speech and video, both symmetrical: up to 384 kbit/s also asymmetrical: up to 2 Mbit/s

UTRA/FDD puts wide- band- CDMA (W-CDMA) together with DSSS (Direct Sequence Spread Spectrum) as spread spectrum technique channel separation by carrier frequencies, spreading code and phase position (only uplink) ca. 250 channels for used data, data rates up to 2 Mbit/s complex performance control necessary t f in MHz 190 MHz uplink downlink 1920,9 1979,7 carrier 1 5 MHz carrier 12 . 2110,9 2169,7

UTRA/TDD puts wideband- TDMA/CDMA together with DSSS sends and receives on same carrier (TDD) ca. 120 channels for used data, data rates up to 2 Mbit/s channel separation by spread code and time slots less spreading than at FDD precise synchronization necessary lower demand for performance control t f in MHz 1900,1 1920,1 carrier 1 5 MHz carrier 4 . 2010,1 2020,1 carrier 5 carrier 6 uplink downlink

Frequency award for UMTS 1885 1980 1920 2010 2025 2110 2170 60 GHz MHz MBS terrestrial satellite- based Extension Bands (for a future market potential ..from 2005) Extension Band 1 (worldwide similar) – partly terrestrial, partly satellite- based 2520 2670 MHz 470 862 2290 2300 2700 2900 Existing Nets 880 1885 GSM, DECT 1675 1710 satellite-based

UMTS-licenses in Germany E-Plus Hutchison 8.394.492.363 € Group 3G 8.408.706.278 € Vodafone (Mannesmann Mobilfunk) 8.422.920.192 € MobilCom Multimedia 8.369.848.095 € T-Mobil 8.478.344.232 € O2 (VIAG Interkom) 8.445.008.001 € 17.08.2000: each license got 2 x 5 MHz packets, 60 MHz have been given away altogether, 150 MHz are available altogether RegTP determined: - till end of 2003 25 % network coverage - till end of 2005 50 % network coverage

Summary introduced variants are the proposals, which will be supported by Europe, Japan and partly by the USA worldwide accessibility can be realized only with multimode end devices even in Europe combined UTRA-FDD/UTRA-TDD/GSM- devices are necessary (those are realized by the identical frame time of 10ms at relatively low costs)

Wireless Local Networks, WLAN

Why do we need wireless LANs? Advantages flexibility Ad-hoc-network realizable with less expenditure No problems with cables Disadvantages high error vulnerability on the transmission link in comparison to Standard-LANs National restrictions, no international standards at used frequency bands (Industrial Scientific Medical (ISM)- Band) security, costs

Application areas networks in exhibition halls hospitals warehouses airports structure of networks in historic buildings extension of existing wired local area networks in offices, universities etc.

Problems with the use of WLAN‘s physical problems interference: band spreading echo: use of special antennas Hidden Terminal problem: use CSMA/CA data security Wired Equivalent Privacy (WEP) service further development WiFi (Wireless Fidelity), WPA (WiFi Protected Access)

Standards IEEE 802.11 (a,b,g ; optional e,h,i) HomeRF frequency band 2,4 GHz, also in the 5GHz - band data rates: 1 bis 11 Mbit/s (at present, later up to 20 (2,4 GHz) or 54 Mbit/s (5,4 GHz)) WiFi: Wireless Fidelity, certificate from the WECA (Wireless Compatibility Allicance), secures the interoperability between the Radio- LANs and contains improved security mechanisms HomeRF Bluetooth (IEEE 802.15) Frequency band: 2,4 GHz Data rate: 1 Mbit/s; in the future also 20 Mbit/s connection of peripherals HIPERLAN (ETSI) / Wireless ATM frequency bands 5,15 / 5,30 GHz and 17,1 / 17,3 GHz data rates: 24 Mbit/s or 155 Mbit/s however no practical relevance

IEEE 802.11b frequency: transmission power: reach: 2,4 GHz frequency band, also called ISM (= Industrial Scientific Medical Band), not regulated 850 - 950 nm at infrared transmission power: min. 1mW max. 100mW in Europe (1W in the USA) reach: of 10m (IR) to 30km or more with the help of special antennas (directional antennas)

Basic WLAN- structure Ad-hoc-network: 3 connected infrastructure networks: AP STA4 STA5 AP - Access Point

System architecture IEEE 802.11 802.x LAN 802.11 LAN STA1 ESS BSS1 Access Point Portal Distribution System Access Point BSS2 STA2 802.11 LAN STA3

System architecture IEEE 802.11, concepts Station (STA) device with 802.11- concurring interface Access Point allows the access to the distribution system for registered stations and secures accessibility of the stations also beyond the BSS Coordination Function (CF) logical functional unit, which decides when a station can send Basic Service Set (BSS) consists of several stations, that were controlled by an CF, e.g. BSS2 and STA2, STA3

System architecture IEEE 802.11, concepts Distribution System connects several BSS over access points and forms a logically larger net Extended Service Set (ESS) Radio networks, which are connected over Distribution System Portal allows transition into other networks

Overview 802.11 is the most frequently used solution for wireless connection; very strong distribution on the market interesting future option: „Seamless Handover“ between GSM and IEEE 802.11; supported by Cisco, Intel etc. (alternative to UMTS?) higher data rates already standardized or in use 802.11a: physical layer at 5 GHz – Band, data rates up to 54 MBit/s 802.11b: extension to physical layer for the 2,4 GHz – band, data rates up to 11 MBit/s, products available 802.11g: at present the industry works on an extension, shall allow the up to 54Mbit/s in the frequency band around 2.4 GHz Study Group 5GSG: examines the harmonization between IEEE 802.11 and ETSI HiperLAN Task Group e: MAC functions for QoS-Management and to refine improved safety functions, introduction of service classes etc.

802.11 – Norms for WLAN 802.11 Since end of 1990; RadioLAN; B=1-2 MBit/s; ISM-Band F=2,4GHz; low Interoperability and bit rate! 802.11b 11MBit/s, actual Standard, existed NICs and APs; ISM-Band F=2,4GHz; possesses further sub-standards 802.11a Since 2000; competition with 802.11b; up to 54 MBit/s; F=5,1 GHz, correspond. national restrictions: in the buildings 802.11g Ratification March, 2003; first pre-standard products; ISM-Band 2,4GHz; up to 54 MBit/s; 802.11e Sub-standard; planed for end 2003; use of QoS-approaches; realization of multimedia applications/ Voice over IP over WLAN 802.11h Sub-standard / method for 802.11a; optional functionality – transmission power control of radio interface by national via RegTP prescribed norms; correspond. especially for Germany 802.11a or h 802.11i Sub-standard; security approaches for WLAN (encryption, authentication) WPA WiFi Protected Access; Substandard; competition with 802.11i 802.11c Sub-standard; Method of Wireless-Bridging 802.11d Sub-standard; country specifics for 802.11b 802.11f Sub-standard; Routing between radio cells of different vendors by IAPP (Inter-Access-Point Protocol)

Parameters Standards 802.11 802.11 802.11b 802.11a / h 802.11g Frequency band, GHz 2,4 (ISM-Band) 5,1 Bit rate, MBit/s 1-11 11 54 Use field building, territory in the buildings Deployment End 1990 actually Since 2000 Since March 2003 Available Hardware Marketable NICs and APs Experimental operation Pre-standard Products  Data security WEP 64/128/256 bit WEP 802.11i - security approaches for WLAN (encryption, authentication); WPA - WiFi Protected Access (competition with 802.11i) QoS for multimedia-transmission none 802.11e (Ende 2003): use of QoS-approaches; realization of multimedia applications/ Voice over IP Problematic low bit rate low interoperability National restrictions Pre-standard

Example: Lucent Wavelan 802.11b WLAN Card Wireless connection that acts just like a conventional Ethernet link Technical specifications: 11 Mbps wireless connection 40-bit WEP or 104-bit RC4 link layer encryption Interoperability with other cards of IEEE 802.11b (i.e. Cisco Aironet or the Apple Airport Card) Tiny size - a PCMCIA card less than 1 inch Cross-platform support (Linux, Mac, and Win*) Very low cost (comparable to a PCMCIA 10/100 Ethernet card) http://www.lucent.com/

Example: Globalsuntech 802.11b products Bit rates: 22/11/5.5/2/1 MBit/s per channel WEP 64/128/256 Bit Available devices: Card Bus PCMCIA Card PCI Card Mini USB DSSS; selectable channels: USA, Canada - 11 channels Europe - 13 channels Japan - 14 channels Sensitivity, range: 80dBm for 22MBit/s 92dBm for 1MBit/s Cross-platform support (Linux, Win*) http://www.globalsuntech.com/

Further Scenarios (1) Scenario 1: Wireless Access Wireless Access Point (Hub Type) LAN WLAN Wireless PC PCs

Further Scenarios (2) Scenario 2: Wireless Bridging Ethernet Hub Wireless Access Point (Bridge Type) WLAN LAN Wireless PCs

Further Scenarios (3) Scenario 3: Share Wireless AP Internet Cable/DSL-Modem Wireless Access Point (Router Type) WAN WLAN Wireless PCs

Further Scenarios (4) Scenario 4: Wireless/Wired Routing Internet Cable/DSL-Modem Cable/DSL- Wireless/ Wired Router WAN LAN LAN WLAN Wireless PCs

UMTS vs WLAN

Mobility and data rates UMTS: better mobility, connectivity WLAN: higher data rates, more cheap, but no telephone Vehicle 0,4 WLAN UMTS (best support) 2,0 3G – UMTS 5,5 TDSL Walk 2G 65,5 ISDN in minutes, trailer , 30 MB Source: Focus, 34/2002 WLAN Bluetooth Fixed LAN Data rate [Mbit/s] 0,1 1 10 100 Source: http://www.netant.no

WLAN- Spectrum Allocation License exempt. 455 MHz HIPERLAN HIPERLAN High Speed wireless access Sharing rules 100 MHz U-NII U-NII Unlicensed 300 MHz 5100 5200 5300 5400 5500 5600 5700 5800 5900 Frequency [MHz] U-NII ... Unlicensed national information infrastructure source: www.ist-mind.org, www.3gpp.org

Interworking UMTS/WLAN - User should be notified of any possible degradation - subscriber database could be shared, or separated in HLR/HSS (3GPP) or AAA (IETF) format Three classes: - no coupling - loose coupling - tight coupling AAA ... Authentication, authorization, accounting no coupling loose coupling tight coupling UMTS/WLAN as completely independent UMTS/WLAN use same database in AAA format HIPERLAN/2 is connected through UTRAN to UMTS, using special interface - Rapid introduction - no impact on GSN nodes - good handling - no impact on GSN nodes - improved handover performance Pro: Contra: - poor handover - no common database, billing - poor handover - HIPERLAN/2 have to support complete UMTS interface - feasible if operator have both networks

Data security in WLAN and UMTS Data security for WLAN: 802.11i new, additionally standards 802.11a/h and 802.11g complex solution for security packet encryption key distribution via RADIUS -Remote Access Dial-In User Service packet authentication partial compatibility with IPsec relevant against all attacks WPA - WiFi Protected Access preliminary to 802.11i properties similar to 802.11i competition to 802.11i  WEP - Wired Equivalent Privacy additionally to standard 802.11b, partially obsolete!!! users mobility between several Access- Points, without re-configuration (roaming) disadvantages: short key of 64 / 128 bit different, partially contradictory statements to offered security Data security for UMTS: IPsec Client/Server based, Clients and IPsec-Servers negotiate dynamic keys tolerant, relevant for key assignment to IP-subnets and against all Internet-attacks secrecy on the network layer: IP-datagrams TCP/UDP-segments ICMP/SNMP-messages Encryption via DES, 3DES and 40-bit-DES authentication via “IP Encapsulating Security Payload" (RFC 2406, 1998) “IP Authentication Header” (RFC 2402, 1998)

HomeRF (Radio Frequency) competitive standard to IEEE 802.11 Up to 128 network nodes Frequency jump in separations of 3MHz or 5MHz Low costs and support of synchronous services: DECT speech support 2,4 GHz (FHSS), transition power max. 100 mW, Shared Wireless Access Protocol (SWAP): hybrid protocol of DECT (TDMA) and CSMA according to IEEE802.11 (modified) up to 6 wireless fixed network connections however sinking market shares in comparison with IEEE 802.11

HomeRF data rate 1-2 Mbit/s 50 m reach within buildings Supplier: e.g. Intel with ANYPOINT (wireless home network) future: HomeRF + Bluetooth: DUAL MODE SYSTEM (Symbionics) ad-hoc possibly voice transmission - today only few manufactures

Wireless City Networking via 802.16 IEEE Wireless MAN/ ETSI Hiper MAN

Wireless City Networking: scenarios new IEEE 802.16 standards can provide great regions with fast Internet services Use fields: office materials shops cafes at the railway stations to surf at the parks

USA: Wireless MAN Wireless MAN: 802.16-version in USA Backgrounds: competition to T-Mobile USA - mobile radio network provider great number of 802.11-Internet service providers (ISP via Wireless LAN) wide spread 802.11x – networks in the country via 802.11 provided approx. 2500 regions

Europa: Hiper MAN ETSI (European Telecommunications Standard Institute): activities in the range of 802.16 – development of Hiper MAN new marketable products: since July 2004 (according to announcement of Fujitsu Europe)

802.16 / 802.16a Wireless MAN Standard 802.16 Start-Standard 802.16a developed end of month January 2003 frequency bandwidth: 10 up to 66 GHz reach: up to 50 km (30 miles) data rate: up to 134 MBit/s new 802.16x standards can provide great regions with fast Internet service, momentary trial operation in Boston/USA (ISP via Wireless MAN) Start-Standard 802.16a frequency bandwidth: 2-11 GHz data rate: up to 70 MBit/s only predominantly conceptualized for fast links of hotspots can be used to establishment of private DSL-links final operation inset: January 2005

802.16a-Forum Members: Aims: Airspan Networks, Alvarion, Aperto Networks, Ensemble Communication, Fujitsu of America, Intel, Nokia, Proxim, Wi-LAN Aims: to provide compatibility of 802.16a-products among each other

Conclusion: 802.16 vs 802.11 802.11 802.16 advantage: disadvantage: in spite of sharp competition to Mobile Radio (IMT2000/UMTS) 802.11x gained the mass market well-elaborated 802.11x (x = a, b, c, d, e, f, g, h, i, WPA) disadvantage: existing bandwidth problems (at most up to 54 Mbit/s) reach at most up to 100m without directional antennas 802.16 advantage: covers approx. 50km (30 miles) substitution via 802.16 as access techniques possible in future cost-efficient in comparison to 802.11 disadvantage: averaged investment for leased circuits amounting to 1000$ per location necessary sharp competition to Mobile Radio (IMT2000/UMTS): to occupy the market is for Wireless Networks more important as for Mobile Radio! final operation inset: planned January 2005 only

Better than UMTS: future use scenarios of 802.16 Scenario: fast Internet WWW-Server/ Intranet-Firewall Internet (1) via ISDN, Modem, DSL ISP via Wireless MAN WAN PC/LAN (2) via Wireless MAN Access Point WAN Wireless MAN 802.16 up to 50 Km (30 miles) 70-134 Mbit/s Wireless PCs

Bluetooth

Bluetooth - Facts Harald Bluetooth was the King of Denmark in the 10th century 1998 started from Ericsson, Intel, IBM, Nokia, Toshiba Open Standard: IEEE 802.15.1 Generally for wireless Ad-hoc- piconets (Range < 10m) Goal: not expensive One-Chip-Decision for radio/ wireless communication networks Use fields: Connection of peripheral devices Support of Ad-Hoc-Nets Connection of different networks Frequency band in IMS-Range of 2,4 GHz

Bluetooth Pico nets with up to 8 participants (ad-hoc) (one master, slaves) Scatter nets as an association of different pico nets frequency hopping is used for improving of interception safety and system robustness

Bluetooth - properties Range: - 10 cm up to 10 m at 1 mW transmitting power - up to 100m at 100mW Data rates: 433,9 kBit/s asynchronous-symmetrical 723,2 kBit/s / 57,6 kbit/s asynchronous-asymmetrical 64 kBit/s synchronous, voice service In future up to 20 Mbit/s (IEEE 802.15.3) Basic set-up Bluetooth Host- System 2,4-Ghz- HF Bluetooth- Baseband- Controller

Bluetooth-comparison FUNCTION Bluetooth v1.1 IrDA Data 1.1 IEEE802.11 (WLAN) Range w/o PA: 10 meter max. 1 meter max. 50 meter max. Angle: omni-directional ca 30° RF Frequency Band: ISM Band, 2.4 GHz Infrared Radiation Mobility: mobile stationary Data rate: 721kBit/s 4MBit/s 2MBit/s Security level: High Low Source: http://www.okisemi.com

Bluetooth- functionality Not connected Standby Standby t =2 s Inquiry after unknown Address Page after unknown Address connection- status t =0,6 s active states Send data connected t =2 ms t =2 ms PARK HOLD SNIFF Low-Power- states MAC-Address resigned MAC-Address available

Bluetooth – architecture (1) Data Applications Data TCS,SDP,RFCOMM L2CAP connection between Hardware and upper protocol (only necessary, if L2CAP not implemented in Hardware!) HCL LMP connection between end devices In hardware implemented ! Baseband Radio Physical connection interface TCS …Telephony Control Protocol Specification SDP … Service discovery protocol RFCOMM … RF communication protocol (cable replacement protocol) LMP … Link Manager Protocol HCL … Host Controller L2CAP … Logical Link Control and Adaptation Protocol

Bluetooth- architecture (2) Radio Layer - work area: ISM-Band (2,4 Ghz) - Spread Spectrum Communication - Frequency Hopping- Technology - high error rate acceptability through CVSD-encoding at heavy micro wave load Baseband - controls Radio- Layer 2 Modes: - Synchronous, connection-oriented transfer (SCO) voice connections need symmetrical, circuit-switched point-to-point-connections, Master reserves two successive time slots (up- and downstream) - Asynchronous, connectionless transfer (ACL) data transfers need symmetrical or asymmetrical, packet-switched point-to-point/multipoint- transfers, master uses polling CVSD… Continuously Variable Slop Delta (Sprachkodierung)

Bluetooth- architecture Link Manager Protocol 3 Functions - Piconet management - link configuration - security functions Logical Link Control and Adaption Protocol Functions: - Mutiplexing (different applications can use connection between 2 devices simultaneously) - Reduzierung der Paketgröße der Anwendungen auf akzeptable Baseband- Paket- Größe - Quality of Service

Possible configurations Master Slave Piconet Scatter net

possible configurations Piconet Scatternet Slave 3 Slave 1 Master Master Slave 4 Slave 5 Scatternet Slave 2 Piconet 2 Piconet 1 association of different pico nets GSM frequency hopping : jumps in k steps (k = 0…22 or 79) with Δf distances in ISM-band Bluetooth a) Peer to Peer (or 1 Master and 1 Slave) b) Multi-slave (up to 7 "slaves" with 1 Master)

Bluetooth - Frequencies Country Frequency range [MHz] RF channels Multiplier Spain 2445 – 2475 fk = 2449 + k Δf k = 0,…,22 France 2446,5 – 2483,5 fk = 2454 + k Δf Japan 2471 – 2497 fk = 2473 + k Δf other Europe / USA fk = 2402 + k Δf k = 0,…,78 Δf… frequency distance between channels - different frequencies around the world Goal: Harmonization of wavebands Source: http://www.mobileinfo.com

Bluetooth - Framestructure fk fk+1 fk fk+1 Master one Slot Packet Master 3- Slot-packets three slot Packets Slave Slave one Slot Packet one Slot Packet 625 µs one slot 625 µs one slot Multi slot frame Single slot frame source: http://www.intel.com

Bluetooth – security - 128 Bit Key encryption and authentication - every device has own 48 Bit- address - over 281 .1012 devices can keep apart - low range (manipulation only local!) source: http://www.intel.com PIN E2 Link Key E3 Encryption Key Encyption Key Authentication Encryption user input (Initialization) (possible) permanent storage temporary storage

Bluetooth – security Generic access: Three modes - non-secure - service level enforced security - link level enforced security For Devices: two modes - trusted - untrusted for Services: three modes: - services that require authorization and authentication - services that require authentication only - services that are open to all devices Bluetooth device initiates security procedures before the channel is established Bluetooth is not secure enough for critical transmissions (billing etc.) Sources: http://www.niksula.cs.hut.fi, Müller T., Bluetooth Security Architecture

Bluetooth – applications (1) replaces perhaps infrared in the area of the coupling of peripherals completely „Intelligent Shop“ shop informs the buyer about special offers by mobile phone or handles inquiries for offers in the individual halls Bluetooth-capable ticket machine Payment over mobile telephone is carried out without contacts control of home appliances by mobile telephone lower layers are developed further in the context of the IEEE 802.15 working group (WPAN - Wireless Personal Area Networks) higher data rates, further frequencies, but possible interferences with other systems

Bluetooth - applications wireless connection Headset Handy

HIPERLAN HIPERLAN/1 wireless LAN (as extension to conventional LANs) 5,15 - 5,25 GHz, ca. 20 Mbps, reach > 50 m, mobility < 10m/s decentralized Ad-hoc net, no QoS-guarantee HIPERLAN/2 wireless ATM-LAN (as extension to ATM and IP nets) 5,15 - 5,25 GHz, ca. 20 Mbps, reach 50 m, mobility<10m/s cellular structure with base stations, ATM service classes HIPERACCESS point-to-multipoint ATM connections 5,15 - 5,25 GHz, ca. 25 Mbps, reach 5000 m, stationary/quasi-stationary, point-to-multipoint, ATM service classes HIPERLINK point-to-point ATM connection 17,1 - 17,3 GHz, 155 MBit/s, reach 150 m, stationary/quasi-stationary, point-to-point, ATM source: ETSI RES 10, BRAN

Assessment of HIPERLAN despite of some unique characteristics there are no products available yet, only single prototypes is planned as one of the alternatives for BRAN (Broadband Radio Access Network) in the Wireless ATM planned frequencies are originally not worldwide available (5,1-53GHz)

Wireless ATM Requirements: wireless connection of mobile terminals to ATM-networks compatibility to existing standards existing networks should be easily upgradeable guaranteed service quality properties which other wireless nets don't offer UMTS and WLANs don‘t offer any data rates >50 Mbit/s Problems: ATM is conceived for high data rates ATM is optimized on reliable media applications should notice nothing of the wireless mode

Wireless ATM: review WATM still is standardization endeavors, no definite standards approved the WATM forum has tried to standardize as much as possible, the WATM standard is relatively complex WATM supports relatively many configurations: wireless Ad-hoc networks wireless mobile end-devices: access to the network via radio subsystem, similar to access-points mobile end-devices: seamless handover between connected terminals mobile ATM-Switches (for planes, ships, trains etc.) fixed ATM-terminals: conventional ATM fixed terminals with radio access: comparable with line-of-sight radio links It is not arranged completely for which configuration also products will exist

Satellite-based systems

Sample system Inter-Satellite Link (ISL) Mobile User Link (MUL) Gateway Link (GWL) Gateway Ground Station User Spot beams Footprint PSTN, ISDN, GSM, ... Internet

Basics (1) satellites describe elliptical or circular orbit around the earth distance to the earth remains constant: (1) - Appeal of the Earth - Centrifugal force - Mass of the satellite - Earth radius, 6.370km - Distance of the satellite to the Earth’s center - Grounding acceleration, g = 9,81 m/s2 - Angular frequency: - Cycle frequency of the satellite

Basics (2) Formulae transformation: F = m . a (by Newton) Fgrav = k . M . m / r2 (Gravitation between 2 point masses) mg = k . M . m / R2 (Appeal on the Earth surface = Gravitation) k . M = gR2 FG = gR2 m/r2 = gm(R/r)2 (transformed) δt = 2 . (r-R) / c Signal propagation delay Satellite Downlink r-R Uplink

Basics (3) (2) (1) resolved to r gives: that means, the distance of a satellite to the earth's surface depends only on its cycle duration (special case T = 24h - > synchronous distance r=35.786 km) (2) Cycle duration [h] 10 20 30 40 x 106 m 4 12 velocity [x1000km/h] Synchronous distance 35.786 km

Satellite system classes GEO (Geostationary Earth Orbit) ca. 36 000 km MEO (Medium Earth Orbit) ca. 6000 - 12 000 km Van-Allen-belts 2000 - 6000 km 15 000 - 30 000 km (no satellite use possible) LEO (Low Earth Orbit) ca. 500 - 1500 km HEO (Highly Elliptical Orbit)

Geostationary Satellite systems Principle: Satellit Base for Inmarsat Uplink Downlink Constant position to the Earth, 3 satellites cover complete earth (with the exception of the polar caps), satellites move synchronously to the Earth Simple solution, however large distance (36000 km), therefore high signal propagation delay, long life time of the satellites: ~ 15 years low data rates, large transmission power required problems: on the other side of the 60th degree of latitude reception problems (elevation) because of a high transmission power unfavorable for mobile telephones signal propagation delay too high (0.25 s)

LEO- Systems non-stationary satellites (LEO - Low Earth Orbit) distance to the earth ~ 500 - 2000 km shorter signal runtimes (5-10 ms), lower transmission power of the mobile stations sufficing however more satellites necessary, frequent handover between satellites, approximately all 10 min. examples: Teledesic, Globalstar only low transmission power necessary, suitable for mobile phone networks Disadvantages: large number is necessary (50 - 200, or more) fast handovers within satellites are necessary short life time of the satellites because of atmospheric friction (5-8 years)

MEO- Systems ~ 10000km, lower number of satellites necessary : ~12 slow movement: handover between satellites is hardly necessary cycle duration: 6h high elevation enables coverage large, highly-populated areas Problems: signal propagation delay: 70 to 80 ms higher transmission power is necessary special antennas for small cells are necessary

Service transitions in Inmarsat-C-service L-Band 1,5/1,6 GHz Rx/Tx (GPS) Inmarsat Satellite 600 bit/s laptop 600 bit/s Inmarsat - C – End-Terminal Graphic table Terrestrial station Buffer memory X.25 Interface Phone-Interface Telefax- X.25 Net Email System modem PAD Internet Mail Box Fax- Interface Fixed network data + maps text data + maps Email fax laptop desktop desktop desktop

Examples of satellite-based systems Satellites Height Data rate Teledesic (planned) 288 (?) ~ 700 km 64 Mbit/s  2 / 64 Mbit/s  Iridium 66 (+6) ~ 780 km 2,4 / 4,8 kbit/s Globalstar 48 (+4) ~ 1400 km 9,6 kbit/s ICO 10 (+2) ~ 10 000 km 4,8 kbit/s Inmarsat 5 geostationary 2,4 kbit/s Orbcomm 35 LEO-stationary 57,6 kbit/s Globalstar can transfer bi-directionally up to 144 Kbit/s, through combination of channels Orbcomm - first commercial LEO–service worldwide http://Globalstar.com/

Comparison of satellite-based systems GEO MEO LEO Distance, km r = 35.786 km r-R=6000 – 12000 km r-R= 500 – 2000 km Cycle duration, T 24 h 6 h 95 – 120 min Signal propagation delay, t 0.25 s 70-80 ms 10 ms Transmission power, W 10 5 1 Use examples Numerous systems, approx. 2000: Sputnik (1957) Intelsat 1-3 (1965, 1967, 1969) Marisat (1976) Inmarsat-A (1982) Inmarsat-C (1988) ICO 10+2 Iridium (bankrupt, 2000) 66+6 Globalstar, 48+4/ 144 kBit/s Teledesic (2003), 288/ 2-64 MBit/s Orbcomm, 35 Data rate, kBit/s 0.1 – 1 1 – 64000 Life time, years 15 5-8

Global Positioning System, GPS

Overview 24 satellites on the 6 orbits (20200 km, time of circulation = 12h) 5 earth stations (Hawaii, Ascension Island, Diego Garcia, Kwajalein, Colorado Springs) Accuracy: so called P-Code for military applications: on ~6m accurately, partially 2,8m so called Selective Availability Mode, SAM (artificial degradation) for civil applications: < 100m (1.5.2000 disestablished) Functionality principle: Triangulation GPS-receiver calculates distance to the satellite on the base of Time of Arrival of the received signals distances to at least three satellites enables the calculation of position, a fourth satellite can be used for determination of elevation over zero official initiation 1995, testing since 1978

Principle: TOA (Time of Arrival) / TDOA (Time Difference of Arrival) Distance d, Signal Delay T Mobile Object synchronized clocks measurement of signal delay by speed of light between satellite and receiver, for instance T = 100 ms hence calculation of distance: d = T • c = 1 • 10-1s • 3 • 108 m/s = 3 • 107 m = 30.000 km calculation of spheres around each satellite the position is on the intersection point of three spheres

Principles satellites send a signal composed of three components 50 times per second: identification component: PRC (Pseudo Random Code), provides satellite recognition and status information position component: exact position of satellite time component: time point, when signal is transmitted the time offset measured by the receiver is corresponding to the Time of Arrival, from TOA the distance is calculated for measurement of TOA of signals very accurate clocks are required the exact position of the satellites must be known

Sources of errors Clocks highly accurate atom clocks in the satellites simple clocks in the receivers are calibrated via measurement of a fourth satellite Satellite position satellite orbits are relatively stable and forecastable deviations are measured by US DoD deviations are transmitted as correction factor to the satellites using the PRC Miscellaneous error sources atmospheric faults multi-path propagation

Differential GPS, DGPS use of a stationary receiver as reference position of this receiver is exactly known the stationary receiver carries out position determination and calculates correction factor from the actually obtained position on the base of deviations correction factor is delivered to the mobile receiver

DGPS accuracy grades Accuracy under 10cm: Accuracy under 1m: professional applications, for instance is interesting in meterology and respectively for user of well-engineered software decisions (machine control systems etc.) Accuracy under 1m: events mapping, control of machines, traffic control systems, agriculture Guaranteed accuracy under 10m: agriculture/ forestry, railway (wagon search service), car navigation (private/commercial)

Galileo EU-Project for installation of European satellite navigation system initiation: prospective 2008 positioning accuracy: 45cm 30 satellites Approx. costs: 3,2 Billion €

Galileo „ A system that both competes with and complements the American GPS system “ ITS (Intelligent Transport System) based on a constellation of 30 MEO-satellites ground stations providing information concerning the positioning of users in many sectors usable: transport (vehicle location, route searching, speed control, etc.) social services (e.g. aid for the disabled or elderly) the justice system ( border controls) public works (geographical information systems)

Galileo -architecture Service centres GALILEO GLOBAL CONTENT Regional Components Local Components MEO Constellation ... BSS network Local MS Data link s-band s-band . . i-band . . i-band TTC BSS network Local MS OSS Network Data link GEO OSS Network UMTS RMS network Integrity determination &dissemination Navigation control & constellation management EGNOS I-Band- NAV UHF- S&R External complementary systems COSPAS-SARSAT ground segment User segment

Broadcast Systems, Distribution Networks

Overview special variants of asymmetric communication systems HSCSD supports for instance asymmetric connections regarding to data rate, also ADSL WWW is the biggest representative of asymmetric communication: data volume of uplink (URLs) is much lower than downlink (complete HTML-pages) Problem of distribution systems: Sender can be optimized for a large quantity of receivers only, for instance videostreaming Examples: DVB, Digital Video Broadcast DAB, Digital Audio Broadcast

Principle of Distribution Systems A C B B C Time information sequence is optimized for expected access behavior of all consumers A B t Individual access sample of diverse consumers can more or less deviate from expected access behavior

Digital Audio Broadcast, DAB Audio-transmission in CD-Quality Non-sensible towards interferences of multi-path-propagation Use of SFN (Single Frequency Network) – i.e. all senders of some broadcast-program are working on the same frequency as a rule Frequencies: UHF,VHF, for instance: 174-230 MHz, 1452-1492 MHz Modulation methods: DQPSK (Differential Quadrature Phase Shift Keying) Optionally COFDM (Coded Orthogonal Frequency Division Multiplexing) is used with several carrier frequencies inside some DAB-channel (its quantity is between 192 and 1536), 1,5MHz bandwidth for each channel FEC (Forward Error Correction)-mechanism for fault correction Up to 6 stereo-programs by 192 kbit/s in the same frequency band are transmittable alternatively data can be transmitted with up to 1,5 Mbit/s (responding to the used code rate etc.)

Digital Audio Broadcast, DAB 2 Transport Mechanisms Main Service Channel (MSC): Data, Audio, Multimedia 2 Transport Modes: Stream Mode, Packet Mode Fast Information Channel (FIC): Transport of Fast Information Blocks (FIB, 32 Byte) – control data for interpretation of Data in the MSC, can be also used for services such as Traffic Dispatches, Paging etc. Audio-converting: PCM 48 kHz & MPEG2-Audiocompression High transmission rates by high velocities, up to 250 km/h, responding to distance from sender and error security class, use for instance in high-speed train MOT (Multimedia Object Transfer) protocol for data transmission Cyclic repeat and caching of data blocks

Dynamic channel reconfiguration for DAB Ensemble-Configuration Audio 2 192 KBit/s PAD Audio 3 Audio 4 160 KBit/s Audio 5 Audio 6 128 KBit/s Audio 1 Data D2 D3 D1 D6 D7 D4 D8 D5 Temporarily changed Ensemble-Configuration Audio 2 192 KBit/s PAD Audio 4 160 KBit/s Audio 5 Audio 1 Audio 3 128 KBit/s Data D10 D11 D2 D3 D1 D6 D7 D4 D8 D5 Audio 7 96 KBit/s Audio 8

DVB - Digital Video Broadcasting 1991 ELR (European Launching Group) founded Goal: joint digital Television System for Europe Specifications: DVB-S, DVB-T, DVB-C Frequency reaches: 200, 550, 700 MHz Cell size: up to 60 km Used data rate: ~38,5 Mbit/s Velocity of mobile stations: up to 200 km/h Central Unit: combined DVB-Receiver-Decoder (set-top-box) can receive DVB-Data via satellites, B-ISDN, ADSL… some transmission systems offer a feedback channel for Video on Demand etc.

DVB - Digital Video Broadcasting Different Quality Levels defined: SDTV (Standard Definition TV) EDTV (Enhanced DTV) HDTV (High DTV) Data transport: User Data: MPEG2-Container (Data Transfer Unit) like DAB, Container doesn’t define the type of data Service Information about MPEG2-Container-content: NIT (Network Information Table): Information from a provider about offered services and optional data for the receiver SDT (Service Description Table): Description and parameters for each service in the MPEG2-stream EIT (Event Information Table): Data about actual transmission status TDT (Time and Date Table): e.g. updating of DVB-receiver

Possible contents of DVB/MPEG2-Container MPEG2/DVB-Container MPEG2/DVB-Container HDTV EDTV Single channel (High Definition TV) Several channels (Enhanced DTV) MPEG2/DVB-Container MPEG2/DVB-Container SDTV Several channels (Standard TV) Multimedia (data broadcasting)

DVB used as medium for asymmetric Internet-access Client sends data query to Provider, Provider transmits data to the satellite network, receiver obtains data via DVB-receiver Feedback channel can be phone network, for on-demand services Data rates: 6 up to 38 Mbit/s downlink, 33 kbit/s up to over 100 kbit/s (ADSL) uplink Advantages: data can be transmitted in parallel with TV no additional costs for satellite provider low priced for low-density populated areas Disadvantages: all users need satellite antennas only a minor part of the total bandwidth is usable not suitable for high-density populated areas

DVB as medium for the asymmetric Internet-access Satellite provider DVB–Card in the PC dedicated line (user-to-user) Internet Content Provider Service Provider

3. Mobile Computing

Layer 3 Mobile IP v4 & v6 DHCP

Mobile IP (Internet Protocol)

Problem situation computer mobility in heterogenic networks relocation between different IP-subnets Goal: transparent migration and localization, compatibility to IP, no changes of existing routers Idea: introduction of temporary/ actual IP-addresses (also “care-of-address”, COA); mapping of permanent to temporary IP-addresses using localization technique

Requirements to MobileIP according to IETF Transparency: mobile computer is permanently reachable via its previous “home-address” can change its network access point freely can also communicate after coupling/uncoupling Compatibility: supports each layer below IP (also 1 & 2) mobile computer can also communicate with each “non-mobileIP”-computer no changes to existing computer/routers Security: all registering messages must be authenticated

IETF Mobile IP Goals/Restrictions Minimization of overheads: mobile connections are possibly wireless and have limited band width mobile connections have possibly higher error rate Efficiency and scalability: support of a large quantities of mobile computers support of a theoretically Internet-wide mobility

Correspondent Node (CN) Architecture model Foreign Agent (FA) Foreign Subnet Global Internet Mobile Node Anywhere Home Subnet Home Agent (HA) Router Correspondent Node (CN)

Terms Mobile Node (MN) with permanent IP-address from Home Subnet Home Address permanent address of a mobile computer Home Agent (HA) with knowledge of actual residence of all MNs from so called Home Subnet, like GSM-HLR Care of Address temporary address of a mobile computer from Foreign Subnet Foreign Agent (FA) for assignment of temporary IP-addresses (care of address) and packet forwarding to MNs currently residing in its subnet

Log on via Foreign Agent Home Subnet Foreign Subnet 2.) relaying request HA FA MN 1.) Registration.request 3.) relaying.reply {grant, deny} 4.) Registration reply Log on with a FA - Care-of Address (address of FA, is just an intermediate target for all MN- related packets, tunnel-end) or Application of a co-located Care-of Address (address from Foreign-Subnet, MN is tunnel-end itself), but reception of an Agent Advertisement Message with a set “R”-bit, i.e. the MN is forced to log on with FA itself, although it can operate autonomously

Log on by Home Agent directly MN uses co-located Care-of Address MN is returned to Home Network and would like to log on/off itself with the HA Authentication: each mobile entity (MN, HA, FA) must be able to support a “mobility security association”, which is indicated via IP-address and SPI (Security Parameter Index). Mobile IP provides three different Authentication Extensions: Mobile - Home Authentication Ext. Mobile - Foreign Authentication Ext. Foreign - Home Authentication Ext. Home Subnet MN 1.) Registration.request HA 2.) Registration.reply {grant, deny}

Addressing Problem: For the receivers 2 addresses are necessary (permanent and temporary IP-address respectively home address and COA) Methods of resolution: Encapsulation IP in IP, standard method in MobileIPv4 minimal Encapsulation IP-Option (not supported by all implementations)

IP in IP Encapsulation OUTER IP HEADER IP HEADER IP HEADER IP PAYLOAD IP PAYLOAD IP-source/target address of external/outer IP-Header defines the “end- points” of the tunnel IP-source/target address of internal IP-Header represents the actual packet sender respectively receiver Internal IP-Header isn't changed using “Encapsulator” (exception: TTL)

Routing (unicast) Mobile Node: Foreign Agent: in Home Network it operates like each other Node in Foreign Network it must search a Default Router using the following rules: FA COA: ICMP Router Advertisement-Part; IP-source address of Agent Advertisements (lower Prior.) co-located COA: ICMP Router Advertisement for this address Foreign Agent: FA must check by reception of tunneled packets whether internal target address corresponds with one of the IP-addresses of Visitor List FA must route the received packets of registered MN’s!

Routing (unicast) II Home Agent: HA must intercept each packet for absent MN in addition IP-target address of each incoming packets is verified if MN has no mobile coupling presently, the packets sent to it must not be intercepted, MN is situated in Home Subnet and accepts packets itself or is off-line

Routing (necessities) ARP (Address Resolution Protocol): oriented to resolution of IP-addresses in physical (Hardware, Link Layer) addresses (Ethernet: MAC-addresses of controllers) Proxy ARP: Proxy ARP-reply is an ARP-reply, which can be sent instead of a host A by other host B (with its hardware address) Hosts, receiving this reply, associate the hardware-address of node B with the IP-address of node A and send future packets for A to B Gratuitous ARP: is an ARP-reply, which is sent from a host, to force other hosts to update the records in their ARP-Caches this ARP-reply contains the IP-address, which should be changed in the ARP- Caches, as well as the hardware address which should be updated

Routing - Scenario MN leaves Home Network MN decides to register FA Care-of Address Before Registration Request: MN re-sets a reaction on future ARP-requests Registration Request contains and accepts HA Request, implements Gratuitous ARP (IP-address MN ===> own hardware-address) and uses Proxy ARP to respond to ARP-requests corresponding to MN hardware address

Special case: Routing (MN & CN are in the same Subnet) Triangle Routing CN FA CN ===> MN: Foreign Network MN although CN is in the same Subnet like MN, packets are routed respectively tunneled via FA and primarily HA (possibly over half of terrestrial globe)!!! Home Network MN ===> CN: HA Be routed conventionally via Default Router Special case: Routing (MN & CN are in the same Subnet) Relief (IPv4): Route Optimization

Optimizations: Routing Terms: Binding Cache: table with Mobility Bindings of MNs (on CN, can tunnel itself now) Binding Update: message, contains up-to-date Mobility Binding of a MN, particularly the Care-of Address Procedure: Update of Binding Caches Control seamless Handoffs between FA‘s

Updating of Binding Caches Binding Cache of a CN: Care-of Address of one/several MN‘s, with respective Lifetime No Entry: non-optimal Routing, BUT: HA doesn’t only tunnel a datagram from CN, but also sends a Binding Update to it CN should generate/change Binding Cache-Entry only then, when trusted Mobility Binding received (Bind. Upd.) for corresponding MN (ergo: Secure CN <===> HA) If FA receives tunneled Packet for a MN that is no longer in Visitor List, then it must care that corresponding CN receives a Binding Update (Binding Warning to HA)

Smooth Handoff between FAs Problem of Basis-MobileIP: MN is with a new FA, but the packets tunneled to old FA will be lost FA Smooth Handoff: MNs are informed via new FA (packet can be forwarded) also Packets of hosts with non-up-to-date entries in Binding Cache can be forwarded now from old FA to the new FAs Previous Foreign Agent Notification Extension enables to prompt the new FA to inform the old FA (Binding Update Message)

MobileIP v4 & v6 in comparison Routing Optimal Routing, only if MN in the Home Network. (Otherwise non-efficient „Triangle“-Routing) Optimal Routing is generally possible, if CN knows the Care-of Address Bottle neck HA is a possible bottleneck, because all traffic to the MN is processed over it HA is load essentially reduced, because CN‘s can just directly communicate with mit MN‘s Security Authentication is prescribed only by Registration and then also between HA and MN only Authentication and encryption are possible anywhere, because they are supported from IPv6 Robustness Used FA‘s / HA‘s must not be off-line Short-time failure/re-configuration of HA is mastered thanks to Automatic Home Agent Discovery. IPv6 is essentially simpler to upgrade, therewith also Mobile IPv6 Performance No good performance due to IPv4-requirements and non-optimal Routing Essentially better due to requirements from IPv6 (uniform Headers, less Over- heads) and optimal Routing

Assessment Mobile IP enables the unlimited accessibility/roaming of mobile computers using perpetuation of their addresses and step-less transfer between subnets Particularly necessary for applications without “pull”-semantics (for instance, distributed applications with mobile users, videoconferences, VoIP) Keeping of permanent addresses are also important corresponding to Firewalls etc. in the case of call semantics Successive availability in the form of products

Dynamic Host Configuration Protocol (DHCP) Server A Server B Client DHCPDISCOVER Determination of configuration DHCPOFFER Selection of a configuration DHCPREQUEST (reject) (options) Confirmation DHCPACK Properties: permits automatic configuration (IP-address, subnet-mask, router, DNS-Server, ...) and therewith integration of (mobile) computers Client/Server-Model Lease Concept Relevant for management of Care-of-Addresses

DHCP Assessment no secure mechanisms standardized no standardized communication (signalization, for instance information exchange about managed address areas) between DHCP-servers good base for allocation of co-located COAs in MobileIP

IPsec: Network security

IPsec: Security on the network layer (1) IPsec - IP Security Protocol – new developed protocol from TCP/IP-Stack, related to the IPng - Group IPsec uses: encryption services -> DES, TripleDES and 40-bit-DES between hosts at a VPN (virtual private network) specification for Internet Key Management Protocol (IKMP), based on ISAKMP/Oakley (1998, Internet Security Association and Key Management Protocol - ISAKMP) IPSec-tunnels – encapsulation of TCP/IP-data via the ESP/AH- headers: Developed by S.Kent, R. Atkinson „IP Encapsulating Security Payload" (RFC 2406, 1998) and "IP Authentication Header" (RFC 2402, 1998) relevant for key assignment to IP-subnets

IPsec: Security on the network layer (2) Secrecy on the network layer: a sending host encrypts/authenticates data encapsulated in the IP-datagrams TCP/UDP-segments ICMP/SNMP-messages Authentication on the network layer: target host can authenticate source IP-addresses Basic protocols: Authentication Header (AH) Protocol Encapsulation Security Payload (ESP) Protocol AH and ESP both requires target and source Handshake-Routine: establishment of a logical channel via network layer, called Service Agreement (SA) each SA is unidirectional Distinctly determined via: security protocol (AH / ESP) source IP-address Con-ID of 32 Bit

Encapsulation Security Payload (ESP) Protocol offers secrecy, host authentication and data integrity data, ESP trailers encrypted next header field is a trailer in the ESP ESP- authentication field is similar to AH- authentication field; protocol field = 50 ESP-Auth Protocol = 50 ESP-Trailer TCP-/UDP-Segment authenticated encrypted ESP-Header IP-Header

Authentication Header (AH) Protocol offers host authentication and data integrity, but no secrecy AH headers inserted between IP-Header and IP-data field; protocol field = 51 participated routers process datagrams as usually AH-Header consists of: Con-ID authentication data: signed message digest calculated via original IP-Datagram, offers authentication of source hosts and data integrity next header field is specific data type (TCP, UDP, ICMP etc.) TCP-/UDP-Segment AH-Header IP-Header Protocol = 51

Layer 4

Problems of conventional protocols Loss of packets on the radio channels with higher bit-error rate (BER) results in frequent retransmissions of packets and therewith in further efficiency loss TCP-Protocol uses so called “Slow-Start”-mechanisms: window size is reduced by significant packet losses; this is reasonable for fixed networks, to react on overload, but not for packet losses due to higher BER limited suitability of conventional transport protocols for mobile communication!

Conventional protocols Congestion Control: packet loss as a rule, in fixed networks occurs only by overload of several components reducing of transmission rate Slow Start: sender calculates a traffic window size start with window size 1 exponential growth till to Congestion Threshold then linear growth Fast Retransmit / Fast Recovery: If ≥ 3 DUPACK (duplicate ACK) are received -> sender informs about packet losses and repeats missing packets

Resulting problems in mobile environment packet losses due to transmission errors are wrongly interpreted as traffic jam (Congestion)! > Slow Start is also wrong > Ideally the packets lost due to transmission errors are simply repeated (no effects on Congestion Control) great variances of Round-Trip-Time

Scenario Fixed Host Access Point 1 Mobile Host Access Point 2

Solutions Sender- transparent: to hide the packet losses transparent to the sender transmission repeat via Access Point on layer 2 on TCP-layer Wireless-aware sender: sender understands the reason of packet loss explicit notification of senders sender tries to determine the reason of loss Where will be the modifications carried out?: only by the sender only by the receiver only on the transient node (Access Point) combinations

Solution “Split Connection“ Separation between transport functionality in the fixed network respectively in the mobile network: Work- station TCP MSR Mobile TCP Mobile node Fixed network Mobile network Mobile Support Router TCP-Handover by relocation of mobile node MSR MobileTCP is specially optimized (up to 100% of efficiency improvement possible) system-internal TCP-Handovers are necessary, however transparent for fixed computer (Workstation)

Example of I-TCP (indirect TCP) separation of TCP-connection at the Access Point optimized TCP over the wireless Link (not absolutely necessary) no changes of TCP for the fixed network transparent for Fixed Host loss of End-to-End-semantics Fixed Host Access Point 1 Mobile Host „wireless TCP“ „standard TCP“

Example of I-TCP Mobility: status and buffer transfer Fixed Host Access Point 1 Mobile Host Access Point 2

I-TCP Assessment no changes in the fixed network the errors in the wireless part aren’t propagated to the fixed network both parts can be optimized independently relatively simple: „wireless TCP“ concerns one Hop only the properties of wireless networks (bit-error rate, delay time) are known, therefore fast retransmissions are possible loss of End-to-End-semantics additional costs (computation time, storage place) concerning the Access Point high delay times with handover caused by buffering of data by Access Point IT-security mechanisms must be adapted

Example of Snoop transparent extension of Access Point from sender’s viewpoint Access Point listens to the traffic (snoops) and filters the ACKs buffering of data, are sent to the mobile computer after losses of packets in the wireless network a direct retransmission takes place between Access Point and Mobile Host Access Points send NACK after packet losses of MH Fixed Host Access Point 1 Mobile Host „local retransmission” Buffer TCP

Snoop Assessment maintenance of End-to-End-semantics modifications only at the TCP-Stack of Access Points errors in the wireless part can be corrected locally Soft State no status transfer at new Access Point is necessary change is possible, also if the new Access Point possesses no Snoop no complete transparency of wireless connection handling of NACK requires the modifications of MH IT-security: encryption can prevent an access to TCP-Header (most of the up-to-date approaches use End-to-End-encryption!)

Higher Layers and Services

Wireless Application Protocol - WAP Based partially on the materials of WAP-Forum

WAP – Standard Overview Goal: Fusion of Internet-Technologies and mobile radio, creation of new innovative services standardized by WAP-Forum (http://www.wapforum.org), initiated by Ericsson, Nokia, Motorola specifies application environment and protocols for mobile end-devices such as radio phones, PDAs, pagers

Why WAP? Mobile radio networks and mobile phones possess special properties and requirements Display: sizes and presented colors, numerical keyboard, lower processor performance and storage capacity ... Networks: low data rates, high delays and costs WAP offers the use of several carriers TCP/IP, UDP/IP, USSD, SMS, ... USSD - unstructured supplementary service data (GSM) SMS - short message service (GSM)

Why WAP ? WAP-architecture has a modular organization the modules build together a complete Internet-protocol-stack WML-contents can be queried by HTTP-request-messages WAP uses XML (eXtensible Markup Language)-Standard as well as optimized contents and protocols user interface of conventional end-devices is supported by WML-components enhances acceptance by users WAP uses conventional HTTP-Servers existing development strategies are applicable in the future (common gateway interface - CGI, active server pages - ASP, netscape server API - NSAPI...)

Why HTTP/HTML doesn’t suffice? Big pipe - small pipe syndrome <HTML> <HEAD> <TITLE>NNN Interactive</TITLE> <META HTTP-EQUIV="Refresh" CONTENT="1800, URL=/index.html"> </HEAD> <BODY BGCOLOR="#FFFFFF" BACKGROUND="/images/9607/bgbar5.gif" LINK="#0A3990" ALINK="#FF0000" VLINK="#FF0000" TEXT="000000" ONLOAD="if(parent.frames.length!=0)top.location='http://nnn.com';"> <A NAME="#top"></A> <TABLE WIDTH=599 BORDER="0"> <TR ALIGN=LEFT> <TD WIDTH=117 VALIGN=TOP ALIGN=LEFT> Internet HTTP/HTML Converting to binary format Mobile radio networks <WML> <CARD> <DO TYPE="ACCEPT"> <GO URL="/submit?Name=$N"/> </DO> Enter name: <INPUT TYPE="TEXT" KEY="N"/> </CARD> </WML> 010011010011110110010011011011011101010010011010 WAP

WAP-overview WAP-standard defines: Environment = Wireless Application Environment (WAE) WML (Wireless Markup Language) micro-browser WMLScript virtual machine WMLScript standard library Wireless Telephony Application (WTA) Interface Contents = WAP Content Types Layer architecture Wireless Session Protocol (WSP) Wireless Transaction Protocol (WTP) Wireless Datagram Protocol (WDP) Interface definitions for mobile network

Comparison: Internet/WWW and WAP Wireless Application Protocol HTML JavaScript Wireless Application Environment (WAE) other services and applications Session Layer (WSP) HTTP Transaction Layer (WTP) TLS - SSL Security Layer (WTLS) Transport Layer (WDP) TCP/IP UDP/IP Carrier: SMS USSD CDMA CDPD etc.. GPRS SMS - Short Message Service (GSM), GPRS - General Packet Radio Service (GSM II+), CDMA - Code Division Multiple Access, CDPD - Cellular Digital Packet Data

Wireless Application Environment - WAE environment for distributed applications with specific reference to low-performance end-devices with limited operation comfort and mobile radio networks Goals: network-independent application environment optimized for application in mobile radio systems Internet, i.e. WWW–programming model high interoperability level

WAE – abstract network architecture WSP/HTTP Request {URL} Client Gateway Network Application WSP/HTTP Reply {Content}

Constituents Architecture WML WMLScript WTA Content formats Programming model Browser, Gateway, Content Server WML as page markup language WMLScript as scripting language WTA offers access to phone services Content formats sets free-defined formats: bitmaps, phonebook records, dates ...

Options User Agent Profiling Push-model to user, end-device, ... adapted contents Push-model network initiates delivery of contents Options for performance improvement Caching, ...

Sample: WAP-Gateway Client Web Server WAP Gateway WML Encoder WML-Script WTAI etc. WAE User Agent Web Server Contents CGI Scripts etc. WML Decks, WML-Script WAP Gateway WML Encoder WMLScript Compiler Protocol adapter WSP/WTP HTTP

Sample: WAP - Application Server Client WML WML-Script WTAI etc. WAE User Agent WAP Application Server WML Encoder WMLScript Compiler Protocol adapter Application logic WSP/WTP WML Decks, WML-Script Contents

Wireless Markup Language - WML(1) HTML-like page markup language different font styles are available, tables and graphics too, but limited based on W3C-XML uses HTML and HDML-elements Deck/Card-metaphor interactions-/selection possibilities are separated in Cards navigation (anchor: #) takes place between Cards Deck-stack corresponds to a WML-file HDML - Handheld Device Markup Language, W3C - World Wide Web Consortium, XML - eXtensible Markup Language

Wireless Markup Language - WML(2) explicit navigation model between Decks Hyperlinks Events from user interface History variables and status-management variable status can tell about validity of a stack

WML– text styles Card Deck <wml> <card id=“Card1” title=“Text Styles”> <p align="left"> <i>italic</i>, <b>bold</b>,<br> <big>big</big>, <small>small</small>, <u>underlined</u> </p> </card> </wml> Card

WML-example (1) Variables Selected input Script call Navigation <card id=„Card1" title=„Currency" newcontext="true"> <p> Amount: <input format="*N" name=„amount" title=„Amount:"/> From: <select name=“from“ value=" USD“ title=„From:"> <option value="EUR">Euro</option> ... <option value="USD">US Dollar</option> </select> To: <select name= ... <br/> = <u>$(conv)</u> <do type="accept" label=„Calculate"> <go href=“bsp.wmls#convert('conv', '$(from)','$(to)',$(amount))"/> </do> <do type="help" label="Help"> <go href="#card1_help"/> </p> </card> Selected input Variables Script call Navigation

WML-example (1): Processing

WML-example (2) Events processing <card id="card1_help" title="Help"> <onevent type="onenterforward"> <go href="bsp.wmls#getInfoDate('date')"/> </onevent> <p> Currency exchange rates stem from Federal Reserve Bank of New York and are from $(date). <do type="prev" label=„Back"> <prev/> </do> </p> </card> </wml> Events processing

WMLScript-overview (1) scripting language, similar to JavaScript procedures, loops, conditions, ... optimized for devices with low storage capacity and CPU-performance integrated with WML, enables: reducing of network workload validation of inputs access to vendor-specific APIs programming of conditional logic

WMLScript-overview (2) Bytecode-based Virtual Machine stack-oriented design ROM-able designed with regard to simple, less work-expensive implementation Compiler in network better utilization of network capacity and end-device storage Standard library basic functionality for processing of strings, URLs, ...

WMLScript-example Procedures Variables Statements extern function getInfoDate(varName) { WMLBrowser.setVar(varName,„June,3,2002"); WMLBrowser.refresh(); } extern function convert(varName,from,to,amount) var multiplier = 0.0; ... if (from == „EUR") if (to == „EUR") multiplier = 1.0; else if (to == „RUR") multiplier = EUR_RUR; } else if ... WMLBrowser.setVar(varName,returnString); Variables Statements

Wireless Telephony Application - WTA (1) offers mechanisms for applications in field of telephony primary focus: operators/providers and vendors security and trust are the emphasis WTA Browser using improvements of standard WML/WMLScript- browsers own interface WTAI (... Interface)

Wireless Telephony Application - WTA (2) WTAI contains: call control, messaging, interface to phonebook, events processing... own Client/Server-interaction model event signalization... security via separation browser and port separated WTAI in WML and WMLScript available

WAE content formats WAE defines uniform formats Goal: Interoperability visit cards, so called IMC vCard Standard dates, IMC vCalendar Standard graphics, WBMP (Wireless BitMaP) compiled WML, WMLScript Goal: Interoperability IMC - Internet Mail Consortium

WAP layer architecture Wireless Session Protocol (WSP) Wireless Transaction Protocol (WTP) Wireless Transport Layer Security (WTLS) Wireless Datagram Protocol (WDP) Carrier A Adaptation Carrier B Adaptation Carrier C Adaptation Carrier D Service D Carrier Service C Carrier Service B Carrier Service A Physical Layer Air Link Technology

Wireless Session Protocol supports Client/Server context (shared state), optimization of content transmission offers semantics and mechanisms, which are based on HTTP and improvements for use in mobile radio networks with low-performance end-devices

WSP overview (1) HTTP elements: Improvements: extensible request/reply methods extensible request/reply headers uniform contents composed objects asynchronous requests Improvements: binary encoding of headers session headers (Client & Server) confirmed and unconfirmed network-initiated delivery (Push)

WSP overview (2) Improvements corresponding to HTTP: negotiations of supported characteristics session suspend/resume multiple complete asynchronous transactions connectionless service Why doesn’t HTTP suffice? no compact encoding insufficient negotiations Push doesn't exist

Characteristics message size protocol options Confirmed Push Facility/ Push Facility (unconfirmed) Session Resume … maximum outstanding (unanswered) requests Header Code Pages (known field names in the protocol headers are separated into pages) ...

Suspend/Resume Server knows, when a Client accepts data (Push) multi-carrier devices dynamical addressing enables release of carrier resources

Wireless Transaction Protocol (WTP) Goal: efficient request/reply-based transport mechanism for mobile radio networks and low-performance end-devices Properties: robust data transmission no explicit connection set up and connection release data are transmitted already with the first packet packet oriented abortion-function for outstanding (unanswered) requests

Wireless Transaction Protocol (WTP) Properties: supports concatenation of messages further WTP features: repeated transmission due to packet loss (selective) fragmentation port numbers (UDP) flow control Transaction = Interaction between Initiator and Responder

WTP – transaction classes (1) non-robust datagram-service for instance for Push during a session shouldn’t substitute WDP the transactions are closed after transmission of Invoke Class 1: robust datagram-service

WTP – transaction classes (2) robust datagram-service with robust Invoke- and robust Result-messages the transactions are closed via the Initiator after answer confirmation of the Responder

Wireless Datagram Protocol (WDP) provides connectionless, non-robust datagram-service is substituted by UDP, if IP the a carrier re-adaptation to the carrier takes place in the Adaptation Layer supports port numbers

Wireless Transport Layer Security (WTLS) enables secure connections, uses protocol elements of known, secure Internet-protocols (TLS) provides mechanisms for encryption, strong authentication, integrity and key management corresponds to guidelines of national authorities offers end-to-end security

WAP & Security WTLS (Wireless Transport Layer Security) offers only security via encryption of transmitted data (Grade #1) presently, similar to TLS, only communication trustiness is protected Grade #2 supports Server- and Client-certificates, for instance via additional chip-cards in mobile phones, so called WIM - Wireless Identification Module

WAP & Security UBS (Switzerland) data with WTLS class 2, 128 bit 3DES encrypted UBS authentication against mobile phone via certificates with a key size of 1024 bit participant authentication against UBS via WAP similarly like via Internet with agreement number, password and list-number automatic connection release (Timeout) embedded after ten minutes without interaction participant is demanded to re-authenticate with password und list-number input Deutsche Bank (Germany) WTLS (Wireless Transport Layer Security) end-to-end-encryption data encryption already at the mobile phone decryption at the server Sources: UBC.ch,db24.de

WAP-example: access to enterprise data Server HTTP Web-Server WAP-Gateway Java-Servlet-API Server WML LDAP/X.500-Directory-Service Dir-X-wap Dir-X-Servlet LDAP-Client LDAP WML- pages Profiles

WAP-example: access to enterprise data Example: Siemens Dir-X Meta-Directory Service as a base of a corporate information pool software-package consists of Directory Server (Dir-X-Metahub) and several Clients, is completely LDAP v3 compatible, based on X.500 2 Gateways outwards: Dir-X-Web and Dir-X-wap secure access also via WAP available, because all security properties of Directory-Servers are handed-on to mobile user registration via phone number and password, the authorizations/licenses are deposited within the system in user profiles Java-Servlets built the kernel components of WAP-connection Dir-X-wap-Server: Servlet-components undertake communication with the Web-Server LDAP-Client provides data exchange between the Dir-X-wap-Server and the directory service

WAP-example: access to enterprise data Dir-X-Wap-Application: consists of a set of WML-pages containing DSL Dir-X-Servlet parses DSL-commands 2 configuration files for an application necessary: Global Profile: contains information for the Servlet Application Profile: stores the data that are necessary to execution of WAP-application In principle, each Web-Server is usable with the product, it must only support the Servlets DSL: Directory Script Language; Language for processing of directory requests from Web- or WML-pages and for representation of obtained results in WML or HTML, contains the language elements for LDAP-access

WAP-examples Bond/Security-Order processing: Consors, Advance Bank, Deutsche Bank Mobile “Yellow Pages” – Orange Telecom Mobile Timetable: wap.hafas.de Mobile Auctioning: wap.yahoo.de, wap.ebay.de Mobile „Last Minute Bargain “: 12snap at Vodafone, presently also with WAP Mobile marketplaces/stock exchanges (Mobile Brokerage): http://www.heizoelboerse.de/ http://www.amazon.de/

WAP-example: Bond/Security-Order Mobile Banking Mobile Brokerage

WAP-example: Bond/Security-Order Private Banking-> Login page Other services ... Lufthansa, Sixt, etc.

WAP-example: Bond/Security-Order Main menu Brokerage ... Bond/security info

WAP-example: Bond/Security-Order Order book Status of bond transactions Executed and deleted orders are indicated in the order book for some days more Partial execution of some order is presented as one open and one executed partial order in the order book Details to an order could be indicated via dial-up of correspondent Links

WAP-example: Bond/Security-Order Portfolio review Bond/security depots

WAP-example: Bond/Security-Order Brief queries exchange rates of Bonds/Securities with a delay of approx. 15Min search criteria Bond/Security-ID and/or Bond/Security-name

WAP-example: soccer/football score source: http://www.wapgoal.com

Further WAP-examples soccer/football auctioning: miscellaneous: scores: http://wap.goal.com auctioning: http://wap.12snap.com miscellaneous: http://wap.yahoo.com

WAP-example: timetable service Input the address ...wait ... Input -> English -> Query... …wait ...

WAP-example: timetable service Input the start & target railway stations ...Dresden, …Hannover ...scroll … Input ..date, time.... …scroll …

WAP-example: timetable service After input … search... ..wait.. Selection of train connections with departure platform ...earlier/later... then probably -> END

For comparison: PC-timetable service Details Options PC-timetable service is still detailed!

WAP-result WML doesn’t bring whole Internet’s diversity to a mobile phone there are no satisfactory rate models at the moment; the data-rates are too low even with GPRS limited input and selection possibilities require a reconsidering of interaction semantics, WAP isn’t oriented for many applications, for instance catalogs with a large selection -> PDAs, appliances, voice input and -recognition with introduction of data services with higher data-rates WAP could lose its relevance possibly -> XHTML however WAP means a first step towards independence from PC by access to Internet contents -> multi-dimensional distribution channels for information WAP means the start for creation of a formidable user population (potentially all mobile radio participants)!

WAP-Improvements: WAP2.0 (1) New version Internet-based data services on mobile phones approved by WAP Forum mid-2001 oriented to GPRS and 3G cellular/UMTS Useful services at WAP2.0 devices color graphics and Pictograms location-specific content, navigational functions and user-friendly menus animation representations and streaming media Multimedia Messaging Service (MMS) large-file downloading (music) synchronization of user information with personal information manager software on a desktop PC in a remote location Source: http://www.wapforum.org

WAP-Improvements: WAP2.0 (2) WAP 2.0 builds upon the latest Internet standards: XHTML, TCP/IP, HyperText Transfer Protocol (HTTP/1.1) and Transport Layer Security (TLS) uses mostly TCP as transport optimized for small low-performance end-devices WAP 2.0 supports additionally: Wireless Telephony Application (WTA), Push, and User Agent Profile (UAPROF) utilize more advanced features in WAP 2.0 than in WAP1.x

WAP-Improvements: WAP2.0 (3) Application development easier development of WAP applications More comfortable user environment Migration aspects WAP2.0 offers a migration to XHTML (Extensible Hypertext Markup Language) and TCP (Transmission Control Protocol) Supporting XHTML, WAP 2.0 reduces development costs, allowing developers to write applications for both PC and WAP Security offers more secure due to “end-to-end encryption” (from the mobile device to the server)

WAP2.0 and i-mode Competition & Fusion NTT DoCoMo's I-Mode is a serious competitor of WAP2.0 NTT DoCoMo's I-Mode moves in the direction of support of XHTML and TCP, too I-mode and WAP2.0 will probably converge

i-Mode An overview Based partially on the materials of NTT-DoCoMo

Structure

Overview i-Mode is a product and a trademark of NTT-DoCoMo The enterprise NTT-DoCoMo started in February 1999 with a proprietary development: i-Mode, although NTT-DoCoMo is the member of WAP-Forum itself Meantime i-Mode has got a large number of registered users : over 33 millions Source: http://www.nttdocomo.com

Properties i-Mode is packet oriented always online, no time delays to dial-up billing regarding data volumes and not regarding to time simple page markup language – compact HTML (cHTML) End of 2002: change into XHTML (WAP 2.0) a great success in Japan, because private computers and private Internet access over fixed networks are infrequent In Germany E-plus has started i-Mode on 16th march 2002

compact HTML cHTML or compact HTML is a language subset of HTML very simplified HTML Lists, Forms, Selections, Input fields are possible no Frames, no Tables, no CSS 166 additional pictograms, for instance Fine Heartbreak Motor sports WC

compact HTML (2) Access key-Attribute for direct link activation respectively for direct selection of input fields pictures can be displayed only in GIF-format, max. 5 KB per page. GIF-pictures mustn’t larger than 120*128 dots (little display) also animated GIFs 256 colours (capable of Display) Compact HTML Sites look like “normal” HTML, so also “normal” Browsers like Netscape can work with them i-Mode – on a mobile phone an i-Mode screenshot

Network Configuration

i-Mode network architecture Connection Network [NSP/Corporate LAN] PDC: Personal Digital Cellular Telecommunication System PDC-P: PDC Packet System BS: Base Station IP: Information Provider M-PGW: Mobile Message-Packet Gateway Module MS: Mobile Station M-SCP: Mobile-Service Control Point NSP: Network Service Provider PGW: Packet Gateway Module PPM: Packet Processing Module IP M-SCP PGW M-PGW i-mode Server Internet IP PPM PPM BS BS BS BS PDC-P Network MS MS MS MS http://www.nttdocomo.co.jp/

i-Mode network architecture (2) i-Mode Server: - consists of multiple server systems (B-,C-,M-Max ..), each server system is responsible for special tasks - represents the contents of „Information Providers“, operates Internet-Mail and i-Mode-Mail, enables the connection to Internet M-PGW (Mobile Message-Packet Gateway Module): transforms the protocols: TCP with i-Mode-Server and TLP (Transport Layer Protocol) with PPM PPM (Packet Processing Module): executes the packet connection with the mobile end-devices/peripherals

i-Mode network architecture (3) M-SCP (Mobile-Service Control Point): authentication of user data (similar to voice communication) PGW (Packet Gateway Module): transition to other networks, for instance to offer the enterprises a Virtual Private Network (VPN)

i-Mode protocol stack RT CC MM LAPDM L1 TLP AL (HTTP) MS TCP/IP L2 L1 UITP/NWMP AL HTTP/ SMTP i-Mode Server PMAP L2 L1 TCP/IP TLP UITP/NWMP M-PGW CC RT MM LAPDM L1 PMAP L2 PPM TLP: Transfer Layer Protocol CC: Call Control MM: Mobility Management RT: Radio Frequency Transmission Management LAPDM: Link Access Protocol on the D-Channel, modified PMAP: Packet Mobile Application Part HTTP: HyperText Transport Protocol SMTP: Simple Mail Transport Protocol UITP: User Information Transfer Protocol NWMP: Network Management Protocol TCP/IP: Transmission Control Protocol/ Internet Protocol L1: Layer1 (Physical Layer Protocol) L2: Layer2 (Data Link Layer Protocol)

i-Mode protocol stack II UITP (User Information Transfer Protocol): transmits user information such as, for instance, MSN (Mobile Subscriber Number) to i-Mode-Server NWMP (Network Management Protocol): performs i-Mode Service-functions TLP (Transfer Layer Protocol): has a simplified transmission procedure and can transmit the signalization and user data together

Java for mobile phones base: Java 2 micro edition and Java MIDP (Mobile Information Device Profile) downloading of Java-programs (ca. 30-50 kByte); color representation; applications, also games etc. billing via micro-payment of operator (ca. 1-5 € per application) products e.g. of Nokia, Ericsson, Siemens; support through big operators

M-Commerce - applications Mobile Shopping Mobile Banking Mobile Brokerage Mobile Traveling

Pervasive Computing Operation as parallel as possible of all users independent of the terminal, it means terminals with different equipment (PC‘s, mobile phones, PDAs, Applicances, etc.) should be supported by most different entrance nets It means finding a suitable system architecture for “multidimensional“ Internet communication (e.g. regarding end terminals) over *ML (Markup Languages)

System architecture, one-dimensional Thin Clients databases, etc. WWW-Browser Web Server Application Server Firewall Firewall

System architecture, one-dimensional Browser- Client Thin Client Transaction- monitors business Software Mainframe- applications data bases Outer Firewall Inner Firewall Web-Server HTML- Dokumente HTML- documents CGI- scripts Application- Server proprietary protocols HTTP Stateless-connection stateful-connection Internet Inter-ORB Protocol SOAP (Simple Object Access Protocol)

Properties of application servers main characteristics: object-oriented communication systems component- framework transaction concepts security concepts connection of legacy applications integration of WWW-services general support of design, deployment and runtime

System architecture, two- dimensional Thin Clients Data bases, etc. WWW-Browser Web Server Application Server Firewall Firewall WAP Server …e.g.: BEA WebLogic M-Commerce Solution WAP-Browser

System architecture, two- dimensional WAP-Server Application Server + WWW Server XSL- Prozessors Servlets EJBs Backend convert XML into HTML, WML call data from the EJBs and generate e.g. XML standardize access to Backend, create business logic

XML (Extensible Markup Language) design principles use in the Internet more powerful than HTML separation of content and style possibility of definition of user-specific document-types ability of XML-document processing

XML- document „bibliography“ reference to Style Sheet File special tags

Valid and well-formed documents XML-Documents can have a DTD (Document Type Definition). The DTD can be contained in the document or can be referenced by a link. A DTD specifies, which tags are permitted and how these can be combined. It has a special meaning for the processing of documents. The processing programs can check XML- documents for structural errors with the help of DTD. If there is no error then a document is valid! Well-formed documents contain no DTD- reference, but fulfill the XML-syntax-rules.

Accompanying Style Sheet File RULE for root-element Insert of lower elements Cycle

Presentation in MS IE 5.0 correspondently IE6.0

Other Style Sheet File

Other presentation via XSL

Change of XML- documents presentation for processing XSL- Processor EDI/WML XSL EDI: Electronic Document Interchange Conversion of XML- documents into workable formats (with the help of XSL-Style-Sheets) e.g. into EDI- formats for commercial data processing in the mobile field very interesting for conversion into WML!

System architecture, multidimensional Access-Server Application Server + WWW Server XSL- Processors Servlets EJBs Backend convert XML into *ML call data from EJBs and generate e.g. XML Standardize access to Backend, create business logic

IBM Websphere Transcoding Publisher syntax customization of content easy installation little administration effort changeable, expandable architecture of components

IBM Websphere Transcoding Publisher Evaluation of used profiles & WAP – capable mobile phone 1.Request over port xx Text Clipper: transforms HTML into WML 7.Output of contents Fragmentation Transcoder: Change into WML-decks

Oracle Application Server Wireless Edition syntactic customization of content renewable, expandable architecture of components good customization of specific content Request Manager Master Service Adapter Trans- former Request Manager authentifies user and calls Master Service Client Request the adapter fetches the Information (via e.g. HTTP, SQL, etc.) Master Service configures und starts an adapter A transformer converts information in suitable Client-format

Oracle Application Server Wireless Edition Expiry of a user request

Oracle Application Server Wireless Edition Adapter and Transformer

Contents customization with XML / XSLT Separation of content and presentation content client- independent in XML XSLT: XSL transformations: a XML- data format is changed into a new data format (not necessarily XML), this new data format can include platform dependent information about the presentation of data besides the main information presentation client- dependent in some XSLTs XML-Support in many data bases the server itself needs additional logic

Contents customization with XML / XSLT server-sided requests: reconnaissance and classification of the client choice of the suitable style sheets parameter handover to XSLT Processing of other documents (e.g. bitmaps)

Example application: Pizza ordering service content and logic in same XML-document no presentation-semantic in XML, so all client- abilities can be used in XSLT but stylesheets are not reusable

Example application: pizza ordering service <?xml version='1.0' encoding="ISO-8859-1" standalone="no" ?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.xsl"?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.lynx.xsl" media="lynx"?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.lynx.xsl" media="palm"?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.wap.xsl" media="wap"?> <?cocoon-process type="xsp"?> <?cocoon-process type="xslt"?> <xsp:page language="java" xmlns:xsp="http://www.apache.org/1999/XSP/Core"> <xsp:logic> class Item extends Vector { private int[] numbers; public Item () { super (); numbers= new int[10]; } public void setNumber (int nr, int a) { numbers[nr]=a; public int getNumber (int nr) { return numbers[nr]; ...

Example application: pizza ordering service <services> <service> <name>Hi Pizza</name> <banner>hellopizza.jpg</banner> <description>Hot Ware on Order</description> <location zipcode ="01277"> <address>Bodenbacher Strasse 16b, 01277 Dresden</address> <phone>03512540707</phone> <fax>03512540708</fax> </location > <location zipcode="01127"> <address>Mohnstraße 50, 01127 Dresden</address> <phone>03518485590</phone> <fax>03518485558</fax> <proposal> <category name="Pizza"> <food> <name>Pizza Kentucky</name> <description>Salami</description> <price size="Normal">8.00</price> <price size="Jumbo">15.00</price> <price size="Pan">10.00</price> </food> ...

Pizza ordering service: PC-presentation

Pizza ordering service: presentation on Palmscape and in WAP

XHTML

XHTML XHTML™ 1.0 is Extensible HyperText Markup Language (Second Edition) reformulation of HTML 4 in XML 1.0 use instead of WML2.0 correspondently cHTML (i-Mode) basis for integration between WAP2.0 and i-Mode WWW: http://www.w3.org/TR/xhtml1/#xhtml

XHTML supporting via as well as WAP-Browsers also Netscape Navigator and Internet Explorer constituents: DTD (Document Definition) XSL (Extensible Stylesheet Language) large quantity of supported tags in comparison with WML2.0 and cHTML CSS frames tables forms/input fields applet calls

XHTML vs HTML XHTML describes data <-> HTML displays data! XHTML – combining HTML and XML, and their strengths XHTML is oriented to internet/PC and mobile internet/ mobile phones and hand helds XHTML - compatibility everything has to be marked up correctly -> "well-formed" documents pages can be read by all XML enabled devices upgrading of XML supported browsers compatibility to all browsers backward browser compatible

Mobile agents

The agent- model an agent-system consists of the agents themselves and an execution engine for working with agents. The execution engine offers basic services to the agents Agent is an independent program generally, it consists of data, code and execution state, it works in interest and order of a third party (e.g. user, application).

Agent system OS Network place 5 place 4 Place 1 Place 3 Hardware Operating System Operating system Hardware Hardware

Agent model migration: transfer of code, data, state Client create Agent code, data, state simple Server- interface result migration: transfer of code, data, state local interactions with server transfer of the result

Properties of mobile agents Advantages: reduction of network load autonomy and asynchronity dynamic adapting in environment heterogeneity robustness and error tolerance scalability personalization and individualization dynamic code-installation encapsulation of protocols Disadvantages: need of special execution engine (Middleware) high security requirements transfer of code, data, state Decision: migration vs. remote communication

Applications E-commerce database requests intelligent e-mails Office applications/workflow traffic telematic Web surfing load balancing virtual enterprise Mobile computing

Existing agent systems Voyager (ObjectSpace) Aglets (IBM) Concordia (Mitsubishi Electric) Grasshopper (IKV++) Odyssey (General Magic) Mole (Stuttgart), Ara (Kaiserslautern) Agent TCL (Dartmouth University) MASIF (OMG) Telescript

Middleware for spontaneous Networking

Vision spontaneous networking of electrical devices (but not only computers) very simple connection platform independence JINI UPnP

JAVA Intelligent Infrastructure, JINI „Middleware“ for spontaneous networking; originally developed from Sun JINI Connection Technology enables dynamic control of networked services and devices Partitioning into so called Lookup Groups: different sets of lookup-services basic operations: Discovery: offers locating of a directory services (lookup service) Join: enables acquaintance/ registration of the services implemented from some device

JAVA Intelligent Infrastructure, JINI Lookup-Service enables locating of services via other users/devices per lookup-operations Leasing offers time-limited allocation of resources (using of services) Jini integrates distributed events processing and distributed transactions further on for co-ordination between services

General procedure: step 1 Lookup service Discovery & join protocol Discovery lookup JINI device / service Client

General procedure: step 2 Lookup Service Proxy download Proxy upload JINI device / service Client

General procedure: step 3 Direct Connection JINI device / service Client synchronization data exchange between Device and Client over own communication protocol

JINI - Details Proxy hides all details of communication and is executed in the form of Client (dynamic installation of Stubs) security over RMI - Security Extension Framework new versions of JINI Starter Kits include advanced possibilities, for instance: Caching of request results by Clients unicast-discovery comfortable control of using period (lease) asynchronous receiving of events among other features further development via JINI Community: for instance JINI Surrogate Architecture: supports devices that do not have all required resources for JAVA and JINI printer working group

JINI - Assessment suitable to support scenarios from the field of Ubiquitous/Pervasive Computing JINI is a part of JAVA 2 Micro Edition

Universal Plug and Play, UPnP reply of Microsoft to JINI Embedded in UPnP- forum with this improvement corresponding to Plug- and- Play Standards, the PC peripheral devices should be connected to a home-network problem-less via Universal Plug and Play diverse devices can communicate with each other like with Jini

Universal Plug and Play, UPnP essentially based on open standards like TCP/IP and therefore is compatible to each network in Windows ME integrated a special toolkit for creation of drivers on the basis of UPnP developed by INTEL

Discovery Description Usage UPnP architecture Common Abstrac-tions Home application Universal PnP Common Interfaces Discovery Description Usage Bus attached (ISA,PCI,USB, IEEE,1394,IR,..) Internet Protocol attached IrDA X10 .. Media Indepen- dence IR PLC .. Network media (Ethernet,HomeRF, HomePNA,..

Further approaches HAVi – Home Audio and Video Interop. essentially supported by the vendors of consumer-electronics field UPnP Forum is interlocked however represented more broadly on the market (specially also in computer-industry) HomePlug consortium for standardizing of data communication over (low voltage) power cable performance like by IEEE 802.11b the members are among others Cisco and Panasonic

Services and system support for Mobile Computing

Mobile Computing: system support Essential properties und requirements: dynamics, localization heterogeneity of networks and end-devices security problems

Mobile distributed applications: example Local Resources, Error Protocols Client Product Data Maintenance technician LAN-Access Main office Caching Mobile Access - very different performance and charges: GSM, ISDN, LAN Software-technical, automatic adaptation to concrete system environment Example: Access to picture data/compressed picture data/graphics/text

Problems and requirements Problem fields: dynamic system and net configuration dynamic change of Quality-of-Service-properties uncoupling/re-connection transparency of resource access security aspects Requirements: connection monitoring and selection treatment of uncoupling/off-sets and migration; emulation of services configuration update localization of mobile servers and clients advanced security and transaction services

Mobile RPC Goals: Mobile Binding Datagram RPC Queued RPC Realization: Transparent call to an alternative server by non-accessibility Datagram RPC Queuing of calls in disconnected status Queued RPC intermediate storage and delivery of results after re-coupling Realization: Attachment on existent RPC- systems (without new implementation or internal code changes)

Time Behavior Datagram RPC T1 T2 Time T3 T4 Client Server DCE RPC Datagram RPC Decoupling Net connection RPC reaches Server Return to Client

Message Queuing: MQ Series example Base: Messages, Queues with Queue Manager dynamic coupling between applications and local Queues via logon/logoff using of Queues for transmission or receiving; also mixed using is possible coupling of distributed Queue Managers via Message Channels Internet Gateway, C++- and Java-Support support of essential operating system platforms

Example scenario decoupling of application through Queue Manager: Computer A Computer B Queue Manager Queue Manager MQGET MQPUT App- lication 1 Queue Manager Queue Manager Message Channel App- lication 2 MQPUT MQGET decoupling of application through Queue Manager: Message forwarding is possible even if application isn’t running

Queue, with optional support of N:M - communication Load balancing (selective delivery) or Parallel processing (replicated delivery) Access to Server via multiple Clients C A D B Queue, with optional support of message priorities E

Message Queuing: Assessment Advantages simple manageability robust message delivery flexible application fields (for instance load balancing, parallelization, batch-transmission of branch data etc.) relevant for easy coupling of programs, for instance via Internet, or for Mobile Computing Disadvantages limited communication semantics interaction model is different than with procedures/method invocations limited accessibility of higher services only several proprietary decisions up to now, only step-by-step standardization

Application Structure Ethernet Ethernet Distributed Database DB E-Fax-Order Branch office Firm xDSL Application Resource Mobile Station Communication path GSM Ethernet Cache Management DB-Access Distributed Database Client X

Domain-concept

Main functionality: Domain and Station Manager Domain Manager: management of all global objects (users, global available resources, stations, net topology) Station Manager: management of all local objects of a station (net access, running applications etc.)

Architecture of Station Manager Application Subsystem (Application Programming Interface) Subsystem (System Calls) Location Service Resource Broker Application Data Mobilizer and Manager Registry Service Bandwidth and Cost Management Service Authentication and Encryption Service Active Database Disconnected Operation Handling Service (CS, QS, CHS, BMC)

Mobile Multimedia Email: message transfer User Agent email protocol Subsystem Queuing Service protocol email Queuing Service email protocol Email Proxy Message Store message transfer Mobile Enhanced Message Handling System

Mobile Multimedia Email: selection of quality parameters Cent Cent

Mobile File Manager: example CODA distributed file system, which offers the unbreakable access to data also in the case of server shut-down or net failure developed at the Carnegie Mellon University based on AFS (Andrew File System, distributed file system in UNIX-environment) relatively transparent to the applications

CODA overview based on the model of „Disconnected Operations” client keeps Read- and Write-access on the data via inset of a local buffer (Cache) also during temporary disconnection from net with re-connection system forwards changes and recognizes potential conflicts for different operating systems available (for instance LINUX, Solaris, Windows)

(“Whole-File-Caching”) CODA system model Replicated Server: High availability Net communication at file open and close Disconnected Client: local data access on Cache Client (“Whole-File-Caching”)

properties of consistence (Coda) Callback logic reference from server to the active client, used for immediate information about file changes via other client after connection failures the file in client cache remains valid till to timeout termination (as a rule several minutes) thereby reduced consistency conflict processing explicitly in interactive form, however low conflict probability

Conflict processing (CODA) extensive automation as objective purpose, however isn’t possibly for: Update/Update-conflict: independent double update of the same file Delete/Update-conflict: independent erasure respectively update of the same file Name/Name-conflict: generating of two files with the same name Manual access after user notification

Cache management (Coda) “Cache-Misses”: searched file isn’t in the Client-Cache processing failure in the disconnected status priority list of important files per user the highest priority is always kept in the cache (for instance by system programs, user profiles, address files etc.) other priorities: exchange strategies correspondent to importance dynamic generated files via list of essential operations referenced (for instance actual test protocol etc.)

File synchronization under Windows Windows: over System Control -> Management -> Services so called „file replication (server)“ for synchronization of data between different servers under Explorer -> Extras -> Synchronization: - Synchronization of own Homepage with PC - Synchronization of Sites in WWW

E-Hand connects existing Enterprise Systems with mobile end-devices platform independent - very simple synchronization and data transfer - supports XML, ODBC and SyncML Advantages: - contains Web-similar user interface for application installation and for mobile participants http://www.ehand.com/ehand/

E- Hand

Mobile databases support Motivation: SFA-Sales-force-automation: -> actual information about clients, competitors and market trends to the field (outside-) workers emergent business transactions on the site -> efficiency increasing Example: Pharmaceutical Industry visit of 6 up to 8 distribution medics per day to bring dialogue to the point more quickly previous information about the medic (contacts, receipt prescription habits) are recallable from the firm-net presently still manually due to dialogue recording and product documentation in the future via mobile databases permanently faster access to data without inconvenient storage, connection establishment etc.

Mobile databases support mobile databases offer principally data synchronization and replication of enterprise servers and for mobile end-devices like PALM etc. due to increasingly mobile business processes there is a necessity of databases, which must perform these functionalities among other things: quickly compatible to as many as possible mobile systems 2 mobile database types: “asynchronous synchronization”: for instance SQL Remote of Sybase data replication between central database and multiple remote databases also offline-working is possible due to email-queuing principle (sent, if connected) “synchronous synchronization”: for instance Sybase Mobilink Synchronization Server co-operation with databases of other vendors (via Server Middleware) permanent connection necessary, for instance via GSM

IBM DB2 Everyplace compatible for instance to Windows CE, PalmOS, EPOC ... footprint: ~150 k (storage requirements) for data balancing DB Everyplace Sync Server is necessary synchronization with other Handhelds without PC! includes so called Mobile Devices Administration Center enables central management of all mobile end-devices of a enterprise supports integration of enterprise data from different databases and other sources (DB2 replication technology, JDBC, Adapter API for customized decisions) data are encrypted during synchronization (56 or 128 Bit) supports automatic conflict processing

IBM DB2 Everyplace Synchronization Server Backend Mobile Devices Microsoft Oracle Informix Sybase Other DBMS (JDBC) Source: http.//www.ibm.com

Oracle Lite 3 constituents: Oracle Lite DBMS iConnect Web-to-go database with low footprint (storage requirements) Java-enabled iConnect components for synchronization and creation of messaging-applications (principle of message queues) Web-to-go components supporting development, deployment and management of mobile Web-applications

Oracle Lite replication via Internet File-based replication

Sybase SQL Anywhere Studio mini-database, can be operated on the PDAs supports PalmOS, EPOC and WindowsCE small „footprint“: ~50kByte developer can adapt the database according to the required SQL-properties, modular design principle synchronization enables data balancing with the enterprises database, all well-known database vendors are supported only the changed data are transmitted both local (for instance B. Hotsync (Palm)) and remote synchronization supported architecture similar to IBM DB2 Mobile Connect (Source: http://www.sybase.com/products/anywhere/)

Further approaches Microsoft Mobile Information Server Lotus Everyplace numerous further products, mostly similar architecture concepts

Further sample applications Traffic management Mobile Information Services M-Commerce Service technician Customer consultant Field workers in general Environmental engineering (measurement data logging) Medic (visits on site)

Traffic management Berlin Paris Dresden Services: Traffic engineering “Global” Provider “Local” Provider Paris Dresden Service Center Services: Traffic engineering Travel information Maintenance service Mobile Office

Traffic management Internet GPS GSM Virtual PSTN/ Private ISDN Network Information Provider Info Internet GPS GSM Center A Center B Virtual Private Network PSTN/ ISDN Distributed Information services End-user Distributed Service-Center

Application scenario: car maintenance Host Printer Notepad HUB PC Terminal

Online-information services Client Server for instance WWW low band width Client (mobile) low battery resource Client/Server-access by individual requests additionally: separate broadcast-channel from Server to the mobile Clients: transmission and caching of frequently requested information; thereby lower battery consumption (receiving less expensive as sending for the Client)

Optimization: basic concept information in Publication-Group: regular Broadcast information in On-Demand-Group: Client/Server-queries exchange between both groups on the basis of: access frequency (for instance on WWW-pages) page modification frequency channel bandwidths clients storage volumes (Cache)

Mobile e-Mail Eudora Internet Suite, consists of: Properties: Eudora email for the Palm computing platform EudoraWeb browser for the Palm Computing platform Eudora Mail Conduit Properties: Eudora and EudoraWeb browser support SSL (Secure Sockets Layer) and TLS (Transport Layer Security), i.e. end-to-end security synchronization of bookmarks between PC Web-Browser and EudoraWeb browser via Eudora Web Conduit synchronization with PC-Email applications several Email-accounts Quelle: http://www.eudora.com

Alternative M-Commerce applications 12snap.de (pronounciation: “one two snap”) Auctioning channel www.paybox.de Cashless payments

Sample: 12snap system architecture external provider mobile radio net D2 center Offers via Cellular Broadcast Internet Automatic processing of the orders which are incoming via phone-service; also coupling of WAP and telephony Call Center Users are registered by 12snap and enable direct debit, respectively booking via the credit card; Orders are sent to a Call-Center via keyboard tone, client identification takes place via his phone number (CLIP = Calling Line Identification Presentation)

Sample: paybox.net Client is registered in the Internet by paybox.net and enables direct debit Client obtains as a result so called Paybox-PINs; using Paybox-PIN client can unblock the transactions purchase payments in the Internet are carried out as follows: Client selects „Paybox“ as a payment type Merchant sends transaction to Paybox-provider via secure data connection Provider dials up the clients via phone numbers stored in his master data then Client can unblock the transaction with his PIN Paybox transfers money via direct debit and forwards it to the Merchant