Wireless/Cellular Technologies

Wireless/Cellular Technologies
Prabhaker Mateti

Mobile Communication Technology according to IEEE (examples)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Mobile Communication Technology according to IEEE (examples) WiFi 802.11a 802.11b 802.11g 802.11h Bluetooth a/b/c/d/e/f/g ZigBee + Mobility WiMAX Personal wireless nw WPAN , .6 (WBAN) b/c Wireless distribution networks WMAN (Broadband Wireless Access) [ (Mobile Broadband Wireless Access)] 802.16e (addition to .16 for mobile devices) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications Schiller Chapter 3 : Media Access
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Mobile Communications Schiller Chapter 3 : Media Access Motivation SDMA, FDMA, TDMA Aloha, reservation schemes Collision avoidance, MACA Polling CDMA, SAMA Comparison Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Universität Karlsruhe Institut für Telematik
Mobilkommunikation SS 1998 Motivation Can we apply media access methods from fixed/wired networks? Example CSMA/CD Carrier Sense Multiple Access with Collision Detection send as soon as the medium is free, listen into the medium if a collision occurs (legacy method in IEEE 802.3) Problems in wireless networks signal strength decreases proportional to the square of the distance the sender would apply CS and CD, but the collisions happen at the receiver it might be the case that a sender cannot “hear” the collision, i.e., CD does not work furthermore, CS might not work if, e.g., a terminal is “hidden” CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Motivation - hidden and exposed terminals
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Motivation - hidden and exposed terminals Hidden terminals A sends to B, C cannot receive A C wants to send to B, C senses a “free” medium (CS fails) collision at B, A cannot receive the collision (CD fails) A is “hidden” for C Exposed terminals B sends to A, C wants to send to another terminal (not A or B) C has to wait, CS signals a medium in use but A is outside the radio range of C, therefore waiting is not necessary C is “exposed” to B A B C CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Motivation - near and far terminals
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Motivation - near and far terminals Terminals A and B send, C receives signal strength decreases proportional to the square of the distance the signal of terminal B therefore drowns out A’s signal C cannot receive A If C for example was an arbiter for sending rights, terminal B would drown out terminal A already on the physical layer Also severe problem for CDMA-networks - precise power control needed! A B C CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Access methods SDMA/FDMA/TDMA
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Access methods SDMA/FDMA/TDMA SDMA (Space Division Multiple Access) segment space into sectors, use directed antennas cell structure FDMA (Frequency Division Multiple Access) assign a certain frequency to a transmission channel between a sender and a receiver permanent (e.g., radio broadcast), slow hopping (e.g., GSM), fast hopping (FHSS, Frequency Hopping Spread Spectrum) TDMA (Time Division Multiple Access) assign the fixed sending frequency to a transmission channel between a sender and a receiver for a certain amount of time The multiplexing schemes presented in chapter 2 are now used to control medium access. CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 15

MACA variant: DFWMAC in IEEE802.11
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 MACA variant: DFWMAC in IEEE802.11 sender receiver idle idle packet ready to send; RTS data; ACK RxBusy time-out; RTS wait for the right to send RTS; CTS time-out  data; NAK ACK time-out  NAK; RTS CTS; data wait for data wait for ACK RTS; RxBusy ACK: positive acknowledgement NAK: negative acknowledgement RxBusy: receiver busy CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Polling mechanisms If one terminal can be heard by all others, this “central” terminal (a.k.a. base station) can poll all other terminals according to a certain scheme now all schemes known from fixed networks can be used (typical mainframe - terminal scenario) Example: Randomly Addressed Polling base station signals readiness to all mobile terminals terminals ready to send can now transmit a random number without collision with the help of CDMA or FDMA (the random number can be seen as dynamic address) the base station now chooses one address for polling from the list of all random numbers (collision if two terminals choose the same address) the base station acknowledges correct packets and continues polling the next terminal this cycle starts again after polling all terminals of the list CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Access method CDMA CDMA (Code Division Multiple Access) all terminals send on the same frequency probably at the same time and can use the whole bandwidth of the transmission channel each sender has a unique random number, the sender XORs the signal with this random number the receiver can “tune” into this signal if it knows the pseudo random number, tuning is done via a correlation function Disadvantages: higher complexity of a receiver (receiver cannot just listen into the medium and start receiving if there is a signal) all signals should have the same strength at a receiver Advantages: all terminals can use the same frequency, no planning needed huge code space (e.g. 232) compared to frequency space interferences (e.g. white noise) is not coded forward error correction and encryption can be easily integrated CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller 28

Mobilkommunikation SS 1998 SDMA/TDMA/FDMA/CDMA Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 GSM, DECT, TETRA, UMTS, LTE Schiller Chapter 4: Wireless Telecommunication Systems Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 How does it work? How can the system locate a user? Why don’t all phones ring at the same time? What happens if two users talk simultaneously? Why don’t I get the bill from my neighbor? Why can an Australian use her phone in Berlin? Why can’t I simply overhear the neighbor’s communication? How secure is the mobile phone system? What are the key components of the mobile phone network? CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 GSM: Overview GSM Global System for Mobile Communication formerly: Groupe Spéciale Mobile (founded 1982) Pan-European standard (ETSI, European Telecommunications Standardization Institute) GSM all over the world 219 countries in Asia, Africa, Europe, Australia, America USA: T-mobile, AT&T, Cinci Bell, … > 4.2 billion subscribers in >700 networks > 75% of all digital mobile phones CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Performance characteristics of GSM
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Performance characteristics of GSM Communication mobile, wireless communication; support for voice and data services Total mobility international access, chip-card enables use of access points of different providers Worldwide connectivity one number, the network handles localization High capacity better frequency efficiency, smaller cells, more customers per cell High transmission quality high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains) Security functions access control, authentication via chip-card and PIN CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Disadvantages of GSM no end-to-end encryption of user data roaming profiles accessible high complexity of the system several incompatibilities within the GSM standards CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 GSM: Mobile Services Bearer Services Telematic Services Supplementary Services bearer services MS GSM-PLMN transit network (PSTN, ISDN) source/ destination network TE MT TE R, S Um (U, S, R) tele services CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Bearer Services Telecommunication services to transfer data between access points Specification of services up to the terminal interface (OSI layers 1-3) Different data rates for voice and data (original standard) data service (circuit switched) synchronous: 2.4, 4.8 or 9.6 kbit/s asynchronous: bit/s data service (packet switched) asynchronous: bit/s Today: data rates of approx. 50 kbit/s possible even more with new modulation CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Telecommunication Services I
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Telecommunication Services I mobile telephony offering the traditional bandwidth of 3.1 kHz Emergency number common number throughout Europe (112); mandatory for all service providers; free of charge; connection with the highest priority (preemption of other connections possible) Multinumbering several ISDN phone numbers per user possible CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Tele Services II: Non-Voice-Teleservices
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Tele Services II: Non-Voice-Teleservices group 3 fax voice mailbox (implemented in the fixed network supporting the mobile terminals) electronic mail (MHS, Message Handling System, implemented in the fixed network) ... Short Message Service (SMS) alphanumeric data transmission to/from the mobile terminal (160 characters) using the signaling channel, thus allowing simultaneous use of basic services and SMS (almost ignored in the beginning now the most successful add-on!) CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Supplementary services
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Supplementary services Services in addition to the basic services, cannot be offered stand-alone Similar to ISDN services besides lower bandwidth due to the radio link May differ between different service providers, countries and protocol versions Important services identification: forwarding of caller number suppression of number forwarding automatic call-back conferencing with up to 7 participants locking of the mobile terminal (incoming or outgoing calls) ... CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Architecture of the GSM system
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Architecture of the GSM system GSM is a PLMN (Public Land Mobile Network) several providers setup mobile networks following the GSM standard within each country components MS (mobile station) BS (base station) MSC (mobile switching center) LR (location register) subsystems RSS (radio subsystem): covers all radio aspects NSS (network and switching subsystem): call forwarding, handover, switching OSS (operation subsystem): management of the network CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 GSM: overview OMC, EIR, AUC fixed network HLR GMSC NSS with OSS VLR MSC VLR MSC BSC BSC RSS CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

segmentation of the area into cells
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 segmentation of the area into cells use of several carrier frequencies not the same frequency in adjoining cells cell sizes vary from some 100 m up to 35 km depending on user density, geography, transceiver power etc. hexagonal shape of cells is idealized (cells overlap, shapes depend on geography) if a mobile user changes cells handover of the connection to the neighbor cell possible radio coverage of the cell cell idealized shape of the cell Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

GSM: system architecture
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 GSM: system architecture radio subsystem network and switching subsystem fixed partner networks MS MS ISDN PSTN Um MSC Abis BTS BSC EIR BTS SS7 HLR VLR BTS BSC ISDN PSTN BTS A MSC BSS IWF PSPDN CSPDN CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Radio subsystem radio subsystem network and switching subsystem Components MS (Mobile Station) BSS (Base Station Subsystem): consisting of BTS (Base Transceiver Station): sender and receiver BSC (Base Station Controller): controlling several transceivers Interfaces Um : radio interface Abis : standardized, open interface with 16 kbit/s user channels A: standardized, open interface with 64 kbit/s user channels MS MS Um Abis BTS BSC MSC BTS A BTS MSC BSC BTS BSS CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Network and switching subsystem
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Network and switching subsystem network subsystem fixed partner networks MSC IWF ISDN PSTN PSPDN CSPDN SS7 EIR HLR VLR Components MSC (Mobile Services Switching Center): IWF (Interworking Functions) ISDN (Integrated Services Digital Network) PSTN (Public Switched Telephone Network) PSPDN (Packet Switched Public Data Net.) CSPDN (Circuit Switched Public Data Net.) Databases HLR (Home Location Register) VLR (Visitor Location Register) EIR (Equipment Identity Register) CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

GSM frequency bands (examples)
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 GSM frequency bands (examples) Type Channels Uplink [MHz] Downlink [MHz] GSM 850 GSM 900 classical extended 0-124, 124 channels +49 channels GSM 1800 GSM 1900 GSM-R exclusive , 0-124 69 channels Additionally: GSM 400 (also named GSM 450 or GSM 480 at / or / MHz) Please note: frequency ranges may vary depending on the country! Channels at the lower/upper edge of a frequency band are typically not used CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Mobile station Terminal for the use of GSM services A mobile station (MS) comprises several functional groups MT (Mobile Terminal): offers common functions used by all services the MS offers corresponds to the network termination (NT) of an ISDN access end-point of the radio interface (Um) TA (Terminal Adapter): terminal adaptation, hides radio specific characteristics TE (Terminal Equipment): peripheral device of the MS, offers services to a user does not contain GSM specific functions SIM (Subscriber Identity Module): personalization of the mobile terminal, stores user parameters R S Um TE TA MT CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Network and switching subsystem
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Network and switching subsystem NSS is the main component of the public mobile network GSM switching, mobility management, interconnection to other networks, system control Components Mobile Services Switching Center (MSC) controls all connections via a separated network to/from a mobile terminal within the domain of the MSC - several BSC can belong to a MSC Databases (important: scalability, high capacity, low delay) Home Location Register (HLR) central master database containing user data, permanent and semi-permanent data of all subscribers assigned to the HLR (one provider can have several HLRs) Visitor Location Register (VLR) local database for a subset of user data, including data about all user currently in the domain of the VLR CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobile Services Switching Center
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Mobile Services Switching Center The MSC (mobile services switching center) plays a central role in GSM switching functions additional functions for mobility support management of network resources interworking functions via Gateway MSC (GMSC) integration of several databases Functions of a MSC specific functions for paging and call forwarding termination of SS7 (signaling system no. 7) mobility specific signaling location registration and forwarding of location information provision of new services (fax, data calls) support of short message service (SMS) generation and forwarding of accounting and billing information CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Operation subsystem The OSS (Operation Subsystem) enables centralized operation, management, and maintenance of all GSM subsystems Components Authentication Center (AUC) generates user specific authentication parameters on request of a VLR authentication parameters used for authentication of mobile terminals and encryption of user data on the air interface within the GSM system Equipment Identity Register (EIR) registers GSM mobile stations and user rights stolen or malfunctioning mobile stations can be locked and sometimes even localized Operation and Maintenance Center (OMC) different control capabilities for the radio subsystem and the network subsystem CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 GSM - TDMA/FDMA MHz 124 channels (200 kHz) downlink frequency MHz 124 channels (200 kHz) uplink higher GSM frame structures time GSM TDMA frame 1 2 3 4 5 6 7 8 4.615 ms GSM time-slot (normal burst) guard space guard space tail user data S Training S user data tail 3 bits 57 bits 1 26 bits 1 57 bits 3 546.5 µs 577 µs CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

GSM hierarchy of frames
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 GSM hierarchy of frames hyperframe 1 2 ... 2045 2046 2047 3 h 28 min s superframe 1 2 ... 48 49 50 6.12 s 1 ... 24 25 multiframe 1 ... 24 25 120 ms 1 2 ... 48 49 50 235.4 ms frame 1 ... 6 7 4.615 ms slot burst 577 µs CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

GSM protocol layers for signaling
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 GSM protocol layers for signaling Um Abis A MS BTS BSC MSC CM CM MM MM RR’ BTSM BSSAP RR BSSAP RR’ BTSM SS7 SS7 LAPDm LAPDm LAPD LAPD radio radio PCM PCM PCM PCM 16/64 kbit/s 64 kbit/s / 2.048 Mbit/s CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobile Terminated Call
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Mobile Terminated Call 1: calling a GSM subscriber 2: forwarding call to GMSC 3: signal call setup to HLR 4, 5: request MSRN from VLR 6: forward responsible MSC to GMSC 7: forward call to current MSC 8, 9: get current status of MS 10, 11: paging of MS 12, 13: MS answers 14, 15: security checks 16, 17: set up connection PSTN calling station GMSC HLR VLR BSS MSC MS 1 2 3 4 5 6 7 8 9 10 11 12 13 16 14 15 17 CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobile Originated Call
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Mobile Originated Call 1, 2: connection request 3, 4: security check 5-8: check resources (free circuit) 9-10: set up call PSTN GMSC VLR BSS MSC MS 1 2 6 5 3 4 9 10 7 8 Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobile Terminated/Originated Call
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Mobile Terminated/Originated Call BTS MS paging request channel request immediate assignment paging response authentication request authentication response ciphering command ciphering complete setup call confirmed assignment command assignment complete alerting connect connect acknowledge data/speech exchange service request MTC MOC CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 4 types of handover 1 2 3 4 MS MS MS MS BTS BTS BTS BTS BSC BSC BSC MSC MSC CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Handover decision receive level BTSold MS HO_MARGIN BTSnew CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 Handover procedure HO access BTSold BSCnew measurement result BSCold Link establishment MSC MS report HO decision HO required BTSnew HO request resource allocation ch. activation ch. activation ack HO request ack HO command HO complete clear command clear complete CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 DECT DECT (Digital European Cordless Telephone) standardized by ETSI (ETS x) for cordless telephones standard describes air interface between base-station and mobile phone DECT has been renamed for international marketing reasons into „Digital Enhanced Cordless Telecommunication“ Characteristics frequency: MHz channels: 120 full duplex duplex mechanism: TDD (Time Division Duplex) with 10 ms frame length multplexing scheme: FDMA with 10 carrier frequencies, TDMA with 2x 12 slots modulation: digital, Gaußian Minimum Shift Key (GMSK) power: 10 mW average (max. 250 mW) range: approx. 50 m in buildings, 300 m open space CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

DECT system architecture reference model
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 DECT system architecture reference model D4 D3 VDB D2 PA PT FT local network HDB PA PT D1 global network FT local network CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 DECT reference model close to the OSI reference model management plane over all layers several services in C(ontrol)- and U(ser)-plane C-Plane U-Plane signaling, interworking application processes network layer OSI layer 3 management data link control data link control OSI layer 2 medium access control physical layer OSI layer 1 CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 DECT layers I Physical layer modulation/demodulation generation of the physical channel structure with a guaranteed throughput controlling of radio transmission channel assignment on request of the MAC layer detection of incoming signals sender/receiver synchronization collecting status information for the management plane MAC layer maintaining basic services, activating/deactivating physical channels multiplexing of logical channels e.g., C: signaling, I: user data, P: paging, Q: broadcast segmentation/reassembly error control/error correction CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 DECT layers II Data link control layer creation and keeping up reliable connections between the mobile terminal and basestation two DLC protocols for the control plane (C-Plane) connectionless broadcast service: paging functionality Lc+LAPC protocol: in-call signaling (similar to LAPD within ISDN), adapted to the underlying MAC service several services specified for the user plane (U-Plane) null-service: offers unmodified MAC services frame relay: simple packet transmission frame switching: time-bounded packet transmission error correcting transmission: uses FEC, for delay critical, time-bounded services bandwidth adaptive transmission “Escape” service: for further enhancements of the standard CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 DECT layers III Network layer similar to ISDN (Q.931) and GSM (04.08) offers services to request, check, reserve, control, and release resources at the basestation and mobile terminal resources necessary for a wireless connection necessary for the connection of the DECT system to the fixed network main tasks call control: setup, release, negotiation, control call independent services: call forwarding, accounting, call redirecting mobility management: identity management, authentication, management of the location register CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Enhancements of the standard
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Enhancements of the standard Several „DECT Application Profiles“ in addition to the DECT specification GAP (Generic Access Profile) standardized by ETSI in 1997 assures interoperability between DECT equipment of different manufacturers (minimal requirements for voice communication) enhanced management capabilities through the fixed network: Cordless Terminal Mobility (CTM) DECT/GSM Interworking Profile (GIP): connection to GSM ISDN Interworking Profiles (IAP, IIP): connection to ISDN Radio Local Loop Access Profile (RAP): public telephone service CTM Access Profile (CAP): support for user mobility DECT basestation GAP Common Air Interface Portable Part fixed network CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 UMTS and IMT-2000 Proposals for IMT-2000 (International Mobile Telecommunications) UWC-136, cdma2000, WP-CDMA UMTS (Universal Mobile Telecommunications System) from ETSI UMTS UTRA (was: UMTS, now: Universal Terrestrial Radio Access) enhancements of GSM EDGE (Enhanced Data rates for GSM Evolution): GSM up to 384 kbit/s CAMEL (Customized Application for Mobile Enhanced Logic) VHE (virtual Home Environment) fits into GMM (Global Multimedia Mobility) initiative from ETSI requirements min. 144 kbit/s rural (goal: 384 kbit/s) min. 384 kbit/s suburban (goal: 512 kbit/s) up to 2 Mbit/s urban CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Mobilkommunikation SS 1998 IMT-2000 family Interface for Internetworking IMT-2000 Core Network ITU-T GSM (MAP) ANSI-41 (IS-634) IP-Network Flexible assignment of Core Network and Radio Access Initial UMTS (R99 w/ FDD) IMT-DS (Direct Spread) UTRA FDD (W-CDMA) 3GPP IMT-TC (Time Code) UTRA TDD (TD-CDMA); TD-SCDMA 3GPP IMT-MC (Multi Carrier) cdma2000 3GPP2 IMT-SC (Single Carrier) UWC-136 (EDGE) UWCC/3GPP IMT-FT (Freq. Time) DECT ETSI IMT-2000 Radio Access ITU-R CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

UMTS protocol stacks (user plane)
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 UMTS protocol stacks (user plane) UE Uu UTRAN IuCS 3G MSC apps. & protocols Circuit switched RLC RLC SAR SAR MAC MAC AAL2 AAL2 radio radio ATM ATM UE Uu UTRAN IuPS 3G SGSN Gn 3G GGSN apps. & protocols IP, PPP, … IP tunnel IP, PPP, … Packet switched PDCP PDCP GTP GTP GTP GTP RLC RLC UDP/IP UDP/IP UDP/IP UDP/IP MAC MAC AAL5 AAL5 L2 L2 radio radio ATM ATM L1 L1 CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Support of mobility: macro diversity
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Support of mobility: macro diversity Multicasting of data via several physical channels Enables soft handover FDD mode only Uplink simultaneous reception of UE data at several Node Bs Reconstruction of data at Node B, SRNC or DRNC Downlink Simultaneous transmission of data via different cells Different spreading codes in different cells UE Node B Node B RNC CN CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Support of mobility: handover
Universität Karlsruhe Institut für Telematik Mobilkommunikation SS 1998 Support of mobility: handover From and to other systems (e.g., UMTS to GSM) This is a must as UMTS coverage will be poor in the beginning RNS controlling the connection is called SRNS (Serving RNS) RNS offering additional resources (e.g., for soft handover) is called Drift RNS (DRNS) End-to-end connections between UE and CN only via Iu at the SRNS Change of SRNS requires change of Iu Initiated by the SRNS Controlled by the RNC and CN Node B SRNC CN Iub Iu UE Iur Node B DRNC Iub CEG436: Mobile Computing (PM) Prof. Dr. Dr. h.c. G. Krüger E. Dorner / Dr. J. Schiller

Example handover types in UMTS/GSM
UE1 Node B1 RNC1 3G MSC1 Iu UE2 Node B2 Iub Iur UE3 Node B3 RNC2 3G MSC2 UE4 BTS BSC 2G MSC3 Abis A CEG436: Mobile Computing (PM)

Breathing Cells GSM UMTS
Mobile device gets exclusive signal from the base station Number of devices in a cell does not influence cell size UMTS Cell size is closely correlated to the cell capacity Signal-to-nose ratio determines cell capacity Noise is generated by interference from other cells other users of the same cell Interference increases noise level Devices at the edge of a cell cannot further increase their output power (max. power limit) and thus drop out of the cell  no more communication possible Limitation of the max. number of users within a cell required Cell breathing complicates network planning CEG436: Mobile Computing (PM)

Breathing Cells: Example
CEG436: Mobile Computing (PM)

Long Term Evolution (LTE)
Initiated in 2004 by NTT DoCoMo, focus on enhancing the Universal Terrestrial Radio Access (UTRA) and optimizing 3GPP’s radio access architecture Targets: Downlink 100 Mbit/s, uplink 50 Mbit/s, RTT<10ms 2007: E UTRA progressed from the feasibility study stage to the first issue of approved Technical Specifications 2008: stable for commercial implementation 2009: first public LTE service available (Stockholm and Oslo) 2010: LTE starts in Germany LTE is not 4G – sometimes called 3.9G Does not fulfill all requirements for IMT advanced CEG436: Mobile Computing (PM)

Key LTE features Simplified network architecture compared to GSM/UMTS
Flat IP-based network replacing the GPRS core, optimized for the IP-Multimedia Subsystem (IMS), no more circuit switching Network should be in parts self-organizing Scheme for soft frequency reuse between cells Inner part uses all subbands with less power Outer part uses pre-served subbands with higher power Much higher data throughput supported by multiple antennas Much higher flexibility in terms of spectrum, bandwidth, data rates Much lower RTT – good for interactive traffic and gaming Smooth transition from W-CDMA/HSPA, TD-SCDMA and cdma2000 1x EV-DO – but completely different radio! Large step towards 4G – IMT advanced See for all specs, tables, figures etc.! CEG436: Mobile Computing (PM)

High flexibility E-UTRA (Evolved Universal Terrestrial Radio Access)
Operating bands MHz Channel bandwidth 1.4, 3, 5, 10, 15, or 20 MHz TDD and FDD Modulation QPSK, 16QAM, 64QAM Multiple Access OFDMA (DL), SC-FDMA (UL) Peak data rates 300 Mbit/s DL 75 Mbit/s UL Depends on UE category Cell radius From <1km to 100km CEG436: Mobile Computing (PM)

LTE frame structure UL DL UL/DL FDD TDD Radio frame (10 ms) 1 2 ... 7
1 2 ... 7 8 9 FDD Subframe (1 ms) DL 1 2 ... 7 8 9 Synchronization is part of subframe 0 and 5 1 2 ... 7 8 9 TDD UL/DL ... Downlink Pilot Time Slot (data plus pilot signal) Uplink Pilot Time Slot (random access plus pilot signal) Guard Period CEG436: Mobile Computing (PM)

LTE architecture E-UTRAN EPC (Evolved Packet Core) UE2 eNode B UE1 Uu
Mobility Management Entity Serving Gateway Packet-data network Gateway Home Subscriber Server Policy and Charging Rules Function UE2 eNode B UE1 Uu GPRS MME S10 S3 MME HSS X2-U/-C X2-U/-C S1-MME S6 S11 S1-MME X2-U/-C S4 Uu PCRF S1-U X2-U/-C S7 S-GW Rx+ S5 S8 (roaming) Internet, Operators… S1-U P-GW SGi E-UTRAN EPC (Evolved Packet Core) CEG436: Mobile Computing (PM)

LTE advanced GSM – UMTS - LTE Worldwide functionality & roaming
LTE advanced as candidate for IMT-advanced Worldwide functionality & roaming Compatibility of services Interworking with other radio access systems Enhanced peak data rates to support advanced services and applications (100 Mbit/s for high and 1 Gbit/s for low mobility) 3GPP will be contributing to the ITU-R towards the development of IMT-Advanced via its proposal for LTE-Advanced. Relay Nodes to increase coverage 100 MHz bandwidth (5x LTE with 20 MHz) CEG436: Mobile Computing (PM)

Schiller Chapter 7: Wireless LANs
Wireless IEEE Schiller Chapter 7: Wireless LANs

Characteristics of wireless LANs
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Characteristics of wireless LANs Advantages very flexible within the reception area Ad-hoc networks without previous planning possible (almost) no wiring difficulties (e.g. historic buildings, firewalls) more robust against disasters like, e.g., earthquakes, fire - or users pulling a plug... Disadvantages typically very low bandwidth compared to wired networks (1-10 Mbit/s) due to shared medium many proprietary solutions, especially for higher bit-rates, standards take their time (e.g. IEEE n) products have to follow many national restrictions if working wireless, it takes a vary long time to establish global solutions like, e.g., IMT-2000 CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Design goals for wireless LANs
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Design goals for wireless LANs global, seamless operation low power for battery use no special permissions or licenses needed to use the LAN robust transmission technology simplified spontaneous cooperation at meetings easy to use for everyone, simple management protection of investment in wired networks security (no one should be able to read my data), privacy (no one should be able to collect user profiles), safety (low radiation) transparency concerning applications and higher layer protocols, but also location awareness if necessary … CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Comparison: infrared vs. radio transmission
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Comparison: infrared vs. radio transmission Infrared uses IR diodes, diffuse light, multiple reflections (walls, furniture etc.) Advantages simple, cheap, available in many mobile devices no licenses needed simple shielding possible Disadvantages interference by sunlight, heat sources etc. many things shield or absorb IR light low bandwidth Example IrDA (Infrared Data Association) interface available everywhere Radio typically using the license free ISM band at 2.4 GHz Advantages experience from wireless WAN and mobile phones can be used coverage of larger areas possible (radio can penetrate walls, furniture etc.) Disadvantages very limited license free frequency bands shielding more difficult, interference with other electrical devices Example Many different products CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Comparison: infrastructure vs. ad-hoc networks
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Comparison: infrastructure vs. ad-hoc networks infrastructure network AP: Access Point AP AP wired network AP ad-hoc network CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

802.11 - Architecture of an infrastructure network
Freie Universität Berlin Institut of Computer Science Architecture of an infrastructure network Mobile Communications 2002 Station (STA) terminal with access mechanisms to the wireless medium and radio contact to the access point Basic Service Set (BSS) group of stations using the same radio frequency Access Point station integrated into the wireless LAN and the distribution system Portal bridge to other (wired) networks Distribution System interconnection network to form one logical network (EES: Extended Service Set) based on several BSS LAN 802.x LAN STA1 BSS1 Portal Access Point Distribution System Access Point ESS BSS2 STA2 STA3 LAN Prof. Dr.-Ing. Jochen Schiller 9

802.11 - Architecture of an ad-hoc network
Freie Universität Berlin Institut of Computer Science Architecture of an ad-hoc network Mobile Communications 2002 Direct communication within a limited range Station (STA): terminal with access mechanisms to the wireless medium Independent Basic Service Set (IBSS): group of stations using the same radio frequency LAN STA1 IBSS1 STA3 STA2 IBSS2 STA5 STA4 LAN Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science
Mobile Communications 2002 IEEE standard fixed terminal mobile terminal infrastructure network access point application application TCP TCP IP IP LLC LLC LLC MAC MAC 802.3 MAC 802.3 MAC PHY PHY 802.3 PHY 802.3 PHY CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Layers and functions MAC access mechanisms, fragmentation, encryption MAC Management synchronization, roaming, MIB, power management PLCP Physical Layer Convergence Protocol clear channel assessment signal (carrier sense) PMD Physical Medium Dependent modulation, coding PHY Management channel selection, MIB Station Management coordination of all management functions Station Management LLC DLC MAC MAC Management PLCP PHY Management PHY PMD CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

802.11 - Physical layer (legacy)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Physical layer (legacy) 3 versions: 2 radio (typ. 2.4 GHz), 1 IR data rates 1 or 2 Mbit/s FHSS (Frequency Hopping Spread Spectrum) spreading, despreading, signal strength, typ. 1 Mbit/s min. 2.5 frequency hops/s (USA), two-level GFSK modulation DSSS (Direct Sequence Spread Spectrum) DBPSK modulation for 1 Mbit/s (Differential Binary Phase Shift Keying), DQPSK for 2 Mbit/s (Differential Quadrature PSK) preamble and header of a frame is always transmitted with 1 Mbit/s, rest of transmission 1 or 2 Mbit/s chipping sequence: +1, -1, +1, +1, -1, +1, +1, +1, -1, -1, -1 (Barker code) max. radiated power 1 W (USA), 100 mW (EU), min. 1mW Infrared nm, diffuse light, typ. 10 m range carrier detection, energy detection, synchronization CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

FHSS PHY packet format (legacy)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 FHSS PHY packet format (legacy) Synchronization synch with pattern SFD (Start Frame Delimiter) start pattern PLW (PLCP_PDU Length Word) length of payload incl. 32 bit CRC of payload, PLW < 4096 PSF (PLCP Signaling Field) data of payload (1 or 2 Mbit/s) HEC (Header Error Check) CRC with x16+x12+x5+1 80 16 12 4 16 variable bits synchronization SFD PLW PSF HEC payload PLCP preamble PLCP header CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 MAC layer I - DFWMAC Traffic services Asynchronous Data Service (mandatory) exchange of data packets based on “best-effort” support of broadcast and multicast Time-Bounded Service (optional) implemented using PCF (Point Coordination Function) Access methods DFWMAC-DCF CSMA/CA (mandatory) collision avoidance via randomized „back-off“ mechanism minimum distance between consecutive packets ACK packet for acknowledgements (not for broadcasts) DFWMAC-DCF w/ RTS/CTS (optional) Distributed Foundation Wireless MAC avoids hidden terminal problem DFWMAC- PCF (optional) access point polls terminals according to a list CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 MAC layer II Priorities defined through different inter frame spaces no guaranteed, hard priorities SIFS (Short Inter Frame Spacing) highest priority, for ACK, CTS, polling response PIFS (PCF IFS) medium priority, for time-bounded service using PCF DIFS (DCF, Distributed Coordination Function IFS) lowest priority, for asynchronous data service DIFS DIFS PIFS SIFS medium busy contention next frame t direct access if medium is free  DIFS CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

802.11 - CSMA/CA access method I
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 CSMA/CA access method I station ready to send starts sensing the medium (Carrier Sense based on CCA, Clear Channel Assessment) if the medium is free for the duration of an Inter-Frame Space (IFS), the station can start sending (IFS depends on service type) if the medium is busy, the station has to wait for a free IFS, then the station must additionally wait a random back-off time (collision avoidance, multiple of slot-time) if another station occupies the medium during the back-off time of the station, the back-off timer stops (fairness) contention window (randomized back-off mechanism) DIFS DIFS medium busy next frame direct access if medium is free  DIFS t slot time (20µs) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller 12

Special Frames: ACK, RTS, CTS
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Special Frames: ACK, RTS, CTS bytes 2 2 6 4 Frame Control Duration Receiver Address CRC Acknowledgement Request To Send Clear To Send ACK bytes 2 2 6 6 4 Frame Control Duration Receiver Address Transmitter Address CRC RTS bytes 2 2 6 4 Frame Control Duration Receiver Address CRC CTS CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 MAC management Synchronization try to find a LAN, try to stay within a LAN timer etc. Power management sleep-mode without missing a message periodic sleep, frame buffering, traffic measurements Association/Reassociation integration into a LAN roaming, i.e. change networks by changing access points scanning, i.e. active search for a network MIB - Management Information Base managing, read, write CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Synchronization using a Beacon (infrastructure)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Synchronization using a Beacon (infrastructure) beacon interval (20ms – 1s) B B B B access point busy busy busy busy medium t B value of the timestamp beacon frame CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Synchronization using a Beacon (ad-hoc)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Synchronization using a Beacon (ad-hoc) beacon interval B1 B1 station1 B2 B2 station2 busy busy busy busy medium t B value of the timestamp beacon frame random delay CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Power management Idea: switch the transceiver off if not needed States of a station: sleep and awake Timing Synchronization Function (TSF) stations wake up at the same time Infrastructure Traffic Indication Map (TIM) list of unicast receivers transmitted by AP Delivery Traffic Indication Map (DTIM) list of broadcast/multicast receivers transmitted by AP Ad-hoc Ad-hoc Traffic Indication Map (ATIM) announcement of receivers by stations buffering frames more complicated - no central AP collision of ATIMs possible (scalability?) APSD (Automatic Power Save Delivery) new method in e replacing above schemes CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Power saving with wake-up patterns (infrastructure)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Power saving with wake-up patterns (infrastructure) TIM interval DTIM interval D B T T d D B access point busy busy busy busy medium p d station t T TIM D DTIM awake d data transmission to/from the station B broadcast/multicast p PS poll CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Power saving with wake-up patterns (ad-hoc)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Power saving with wake-up patterns (ad-hoc) ATIM window beacon interval B1 A D B1 station1 B2 B2 a d station2 t B A transmit ATIM D beacon frame random delay transmit data a d awake acknowledge ATIM acknowledge data CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Roaming No or bad connection? Then perform: Scanning scan the environment, i.e., listen into the medium for beacon signals or send probes into the medium and wait for an answer Reassociation Request station sends a request to one or several AP(s) Reassociation Response success: AP has answered, station can now participate failure: continue scanning AP accepts Reassociation Request signal the new station to the distribution system the distribution system updates its data base (i.e., location information) typically, the distribution system now informs the old AP so it can release resources Fast roaming – r e.g. for vehicle-to-roadside networks CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 WLAN: IEEE b Data rate 1, 2, 5.5, 11 Mbit/s, depending on SNR User data rate max. approx. 6 Mbit/s Transmission range 300m outdoor, 30m indoor Max. data rate ~10m indoor Frequency DSSS, 2.4 GHz ISM-band Security Limited, WEP insecure, SSID Availability Many products, many vendors Connection set-up time Connectionless/always on Quality of Service Typ. Best effort, no guarantees (unless polling is used, limited support in products) Manageability Limited (no automated key distribution, sym. Encryption) Special Advantages/Disadvantages Advantage: many installed systems, lot of experience, available worldwide, free ISM-band, many vendors, integrated in laptops, simple system Disadvantage: heavy interference on ISM-band, no service guarantees, slow relative speed only CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

IEEE 802.11b – PHY frame formats
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 IEEE b – PHY frame formats Long PLCP PPDU format 128 16 8 8 16 16 variable bits synchronization SFD signal service length HEC payload PLCP preamble PLCP header 192 µs at 1 Mbit/s DBPSK 1, 2, 5.5 or 11 Mbit/s Short PLCP PPDU format (optional) 56 16 8 8 16 16 variable bits short synch. SFD signal service length HEC payload PLCP preamble (1 Mbit/s, DBPSK) PLCP header (2 Mbit/s, DQPSK) 96 µs 2, 5.5 or 11 Mbit/s CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Channel selection (non-overlapping)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Channel selection (non-overlapping) Europe (ETSI) channel 1 channel 7 channel 13 2400 2412 2442 2472 2483.5 22 MHz [MHz] US (FCC)/Canada (IC) channel 1 channel 6 channel 11 2400 2412 2437 2462 2483.5 22 MHz [MHz] CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 WLAN: IEEE a Data rate 6, 9, 12, 18, 24, 36, 48, 54 Mbit/s, depending on SNR User throughput (1500 byte packets): 5.3 (6), 18 (24), 24 (36), 32 (54) 6, 12, 24 Mbit/s mandatory Transmission range 100m outdoor, 10m indoor E.g., 54 Mbit/s up to 5 m, 48 up to 12 m, 36 up to 25 m, 24 up to 30m, 18 up to 40 m, 12 up to 60 m Frequency Free , , GHz ISM-band Security Limited, WEP insecure, SSID Availability Some products, some vendors Connection set-up time Connectionless/always on Quality of Service Typ. best effort, no guarantees (same as all products) Manageability Limited (no automated key distribution, sym. Encryption) Special Advantages/Disadvantages Advantage: fits into 802.x standards, free ISM-band, available, simple system, uses less crowded 5 GHz band Disadvantage: stronger shading due to higher frequency, no QoS CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

IEEE 802.11a – PHY frame format
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 IEEE a – PHY frame format 4 1 12 1 6 16 variable 6 variable bits rate reserved length parity tail service payload tail pad PLCP header PLCP preamble signal data 12 1 variable symbols 6 Mbit/s 6, 9, 12, 18, 24, 36, 48, 54 Mbit/s CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Operating channels of 802.11a in Europe
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Operating channels of a in Europe 36 40 44 48 52 56 60 64 channel 5150 5180 5200 5220 5240 5260 5280 5300 5320 5350 [MHz] 16.6 MHz 100 104 108 112 116 120 124 128 132 136 140 channel 5470 5500 5520 5540 5560 5580 5600 5620 5640 5660 5680 5700 5725 16.6 MHz [MHz] center frequency = *channel number [MHz] CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Operating channels for 802.11a / US U-NII
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Operating channels for a / US U-NII 36 40 44 48 52 56 60 64 channel 5150 5180 5200 5220 5240 5260 5280 5300 5320 5350 [MHz] 16.6 MHz center frequency = *channel number [MHz] 149 153 157 161 channel 5725 5745 5765 5785 5805 5825 [MHz] 16.6 MHz CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

WLAN: IEEE 802.11 – current developments (06/2009)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WLAN: IEEE – current developments (06/2009) 802.11c: Bridge Support Definition of MAC procedures to support bridges as extension to 802.1D 802.11d: Regulatory Domain Update Support of additional regulations related to channel selection, hopping sequences 802.11e: MAC Enhancements – QoS Enhance the current MAC to expand support for applications with Quality of Service requirements, and in the capabilities and efficiency of the protocol Definition of a data flow (“connection”) with parameters like rate, burst, period… supported by HCCA (HCF (Hybrid Coordinator Function) Controlled Channel Access, optional) Additional energy saving mechanisms and more efficient retransmission EDCA (Enhanced Distributed Channel Access): high priority traffic waits less for channel access 802.11F: Inter-Access Point Protocol (withdrawn) Establish an Inter-Access Point Protocol for data exchange via the distribution system 802.11g: Data Rates > 20 Mbit/s at 2.4 GHz; 54 Mbit/s, OFDM Successful successor of b, performance loss during mixed operation with .11b 802.11h: Spectrum Managed a Extension for operation of a in Europe by mechanisms like channel measurement for dynamic channel selection (DFS, Dynamic Frequency Selection) and power control (TPC, Transmit Power Control) 802.11i: Enhanced Security Mechanisms Enhance the current MAC to provide improvements in security. TKIP enhances the insecure WEP, but remains compatible to older WEP systems AES provides a secure encryption method and is based on new hardware CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

WLAN: IEEE 802.11– current developments (06/2009)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WLAN: IEEE – current developments (06/2009) 802.11j: Extensions for operations in Japan Changes of a for operation at 5GHz in Japan using only half the channel width at larger range : Current “complete” standard Comprises amendments a, b, d, e, g, h, i, j 802.11k: Methods for channel measurements Devices and access points should be able to estimate channel quality in order to be able to choose a better access point of channel 802.11m: Updates of the standard 802.11n: Higher data rates above 100Mbit/s Changes of PHY and MAC with the goal of 100Mbit/s at MAC SAP MIMO antennas (Multiple Input Multiple Output), up to 600Mbit/s are currently feasible However, still a large overhead due to protocol headers and inefficient mechanisms 802.11p: Inter car communications Communication between cars/road side and cars/cars Planned for relative speeds of min. 200km/h and ranges over 1000m Usage of GHz band in North America 802.11r: Faster Handover between BSS Secure, fast handover of a station from one AP to another within an ESS Current mechanisms (even newer standards like i) plus incompatible devices from different vendors are massive problems for the use of, e.g., VoIP in WLANs Handover should be feasible within 50ms in order to support multimedia applications efficiently CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

WLAN: IEEE 802.11– current developments (06/2009)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WLAN: IEEE – current developments (06/2009) 802.11s: Mesh Networking Design of a self-configuring Wireless Distribution System (WDS) based on Support of point-to-point and broadcast communication across several hops 802.11T: Performance evaluation of networks Standardization of performance measurement schemes 802.11u: Interworking with additional external networks 802.11v: Network management Extensions of current management functions, channel measurements Definition of a unified interface 802.11w: Securing of network control Classical standards like , but also i protect only data frames, not the control frames. Thus, this standard should extend i in a way that, e.g., no control frames can be forged. 802.11y: Extensions for the MHz band in the USA 802.11z: Extension to direct link setup 802.11aa: Robust audio/video stream transport 802.11ac: Very High Throughput <6Ghz 802.11ad: Very High Throughput in 60 GHz Note: Not all “standards” will end in products, many ideas get stuck at working group level Info: 802wirelessworld.com, standards.ieee.org/getieee802/ CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Bluetooth Basic idea Universal radio interface for ad-hoc wireless connectivity Interconnecting computer and peripherals, handheld devices, PDAs, cell phones – replacement of IrDA Embedded in other devices, goal: 5€/device (already < 1€) Short range (10 m), low power consumption, license-free 2.45 GHz ISM Voice and data transmission, approx. 1 Mbit/s gross data rate One of the first modules (Ericsson). CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Bluetooth (was: ) History 1994: Ericsson (Mattison/Haartsen), “MC-link” project Renaming of the project: Bluetooth according to Harald “Blåtand” Gormsen [son of Gorm], King of Denmark in the 10th century 1998: foundation of Bluetooth SIG, 1999: erection of a rune stone at Ercisson/Lund ;-) 2001: first consumer products for mass market, spec. version 1.1 released 2005: 5 million chips/week Special Interest Group Original founding members: Ericsson, Intel, IBM, Nokia, Toshiba Added promoters: 3Com, Agere (was: Lucent), Microsoft, Motorola > members Common specification and certification of products CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 History and hi-tech… 1999: Ericsson mobile communications AB reste denna sten till minne av Harald Blåtand, som fick ge sitt namn åt en ny teknologi för trådlös, mobil kommunikation. CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

…and the real rune stone
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 …and the real rune stone Located in Jelling, Denmark, erected by King Harald “Blåtand” in memory of his parents. The stone has three sides – one side showing a picture of Christ. Inscription: "Harald king executes these sepulchral monuments after Gorm, his father and Thyra, his mother. The Harald who won the whole of Denmark and Norway and turned the Danes to Christianity." This could be the “original” colors of the stone. Inscription: “auk tani karthi kristna” (and made the Danes Christians) Btw: Blåtand means “of dark complexion” (not having a blue tooth…) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Characteristics 2.4 GHz ISM band, 79 (23) RF channels, 1 MHz carrier spacing Channel 0: 2402 MHz … channel 78: 2480 MHz G-FSK modulation, mW transmit power FHSS and TDD Frequency hopping with 1600 hops/s Hopping sequence in a pseudo random fashion, determined by a master Time division duplex for send/receive separation Voice link – SCO (Synchronous Connection Oriented) FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, circuit switched Data link – ACL (Asynchronous ConnectionLess) Asynchronous, fast acknowledge, point-to-multipoint, up to kbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switched Topology Overlapping piconets (stars) forming a scatternet CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Piconet Collection of devices connected in an ad hoc fashion One unit acts as master and the others as slaves for the lifetime of the piconet Master determines hopping pattern, slaves have to synchronize Each piconet has a unique hopping pattern Participation in a piconet = synchronization to hopping sequence Each piconet has one master and up to 7 simultaneous slaves (> 200 could be parked) P S S M P SB S P SB M=Master S=Slave P=Parked SB=Standby CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Forming a piconet All devices in a piconet hop together Master gives slaves its clock and device ID Hopping pattern: determined by device ID (48 bit, unique worldwide) Phase in hopping pattern determined by clock Addressing Active Member Address (AMA, 3 bit) Parked Member Address (PMA, 8 bit)   P  S   SB SB S    M P SB     SB SB SB S     SB P SB SB   SB SB CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Scatternet Linking of multiple co-located piconets through the sharing of common master or slave devices Devices can be slave in one piconet and master of another Communication between piconets Devices jumping back and forth between the piconets Piconets (each with a capacity of 720 kbit/s) P S S S P P M M SB S M=Master S=Slave P=Parked SB=Standby P SB SB S CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Bluetooth protocol stack
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Bluetooth protocol stack audio apps. NW apps. vCal/vCard telephony apps. mgmnt. apps. TCP/UDP OBEX AT modem commands TCS BIN SDP Control IP BNEP PPP Audio RFCOMM (serial line interface) Logical Link Control and Adaptation Protocol (L2CAP) Host Controller Interface Link Manager Baseband Radio AT: attention sequence OBEX: object exchange TCS BIN: telephony control protocol specification – binary BNEP: Bluetooth network encapsulation protocol SDP: service discovery protocol RFCOMM: radio frequency comm. CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Frequency selection during data transmission
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Frequency selection during data transmission 625 µs fk fk+1 fk+2 fk+3 fk+4 fk+5 fk+6 M S M S M S M t fk fk+3 fk+4 fk+5 fk+6 M S M S M t fk fk+1 fk+6 M S M t CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Baseband Piconet/channel definition Low-level packet definition Access code Channel, device access, e.g., derived from master Packet header 1/3-FEC, active member address (broadcast + 7 slaves), link type, alternating bit ARQ/SEQ, checksum 68(72) 54 0-2745 bits access code packet header payload 4 64 (4) 3 4 1 1 1 8 bits preamble sync. (trailer) AM address type flow ARQN SEQN HEC CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 SCO payload types payload (30) HV1 audio (10) FEC (20) HV2 audio (20) FEC (10) HV3 audio (30) DV audio (10) header (1) payload (0-9) 2/3 FEC CRC (2) (bytes) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 ACL Payload types payload (0-343) header (1/2) payload (0-339) CRC (2) DM1 header (1) payload (0-17) 2/3 FEC CRC (2) DH1 header (1) payload (0-27) CRC (2) (bytes) DM3 header (2) payload (0-121) 2/3 FEC CRC (2) DH3 header (2) payload (0-183) CRC (2) DM5 header (2) payload (0-224) 2/3 FEC CRC (2) DH5 header (2) payload (0-339) CRC (2) AUX1 header (1) payload (0-29) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Baseband data rates Payload User Symmetric Asymmetric Header Payload max. Rate max. Rate [kbit/s] Type [byte] [byte] FEC CRC [kbit/s] Forward Reverse DM /3 yes DH no yes DM /3 yes DH no yes DM /3 yes DH no yes AUX no no HV1 na 10 1/3 no 64.0 HV2 na 20 2/3 no 64.0 HV3 na 30 no no 64.0 DV 1 D 10+(0-9) D 2/3 D yes D D ACL 1 slot 3 slot 5 slot SCO Data Medium/High rate, High-quality Voice, Data and Voice CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Baseband link types Mobile Communications 2002 Polling-based TDD packet transmission 625µs slots, master polls slaves SCO (Synchronous Connection Oriented) – Voice Periodic single slot packet assignment, 64 kbit/s full-duplex, point-to-point ACL (Asynchronous ConnectionLess) – Data Variable packet size (1, 3, 5 slots), asymmetric bandwidth, point-to-multipoint SCO ACL SCO ACL SCO ACL SCO ACL MASTER f0 f4 f6 f8 f12 f14 f18 f20 SLAVE 1 f1 f7 f9 f13 f19 SLAVE 2 f5 f17 f21 Prof. Dr.-Ing. Jochen Schiller

Robustness Mobile Communications 2002 Slow frequency hopping with hopping patterns determined by a master Protection from interference on certain frequencies Separation from other piconets (FH-CDMA) Retransmission ACL only, very fast Forward Error Correction SCO and ACL Error in payload (not header!) NAK ACK MASTER A C C F H SLAVE 1 B D E SLAVE 2 G G Prof. Dr.-Ing. Jochen Schiller

Baseband states of a Bluetooth device
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Baseband states of a Bluetooth device standby unconnected inquiry page connecting detach transmit AMA connected AMA active park PMA hold AMA sniff AMA low power Standby: do nothing Inquire: search for other devices Page: connect to a specific device Connected: participate in a piconet Park: release AMA, get PMA Sniff: listen periodically, not each slot Hold: stop ACL, SCO still possible, possibly participate in another piconet CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Example: Power consumption/CSR BlueCore2
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Example: Power consumption/CSR BlueCore2 Typical Average Current Consumption1 VDD=1.8V Temperature = 20°C Mode SCO connection HV3 (1s interval Sniff Mode) (Slave) mA SCO connection HV3 (1s interval Sniff Mode) (Master) 26.0 mA SCO connection HV1 (Slave) mA SCO connection HV1 (Master) mA ACL data transfer 115.2kbps UART (Master) mA ACL data transfer 720kbps USB (Slave) mA ACL data transfer 720kbps USB (Master) mA ACL connection, Sniff Mode 40ms interval, 38.4kbps UART 4.0 mA ACL connection, Sniff Mode 1.28s interval, 38.4kbps UART 0.5 mA Parked Slave, 1.28s beacon interval, 38.4kbps UART 0.6 mA Standby Mode (Connected to host, no RF activity) 47.0 µA Deep Sleep Mode µA Notes: 1 Current consumption is the sum of both BC212015A and the flash. 2 Current consumption is for the BC212015A device only. CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Example: Bluetooth/USB adapter (2002: 50€, today: some cents if integrated) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

L2CAP - Logical Link Control and Adaptation Protocol
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 L2CAP - Logical Link Control and Adaptation Protocol Simple data link protocol on top of baseband Connection oriented, connectionless, and signaling channels Protocol multiplexing RFCOMM, SDP, telephony control Segmentation & reassembly Up to 64kbyte user data, 16 bit CRC used from baseband QoS flow specification per channel Follows RFC 1363, specifies delay, jitter, bursts, bandwidth Group abstraction Create/close group, add/remove member CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 L2CAP logical channels Master Slave Slave L2CAP L2CAP L2CAP 2 d 1 1 d d d d 1 1 d d 2 baseband baseband baseband signalling ACL connectionless connection-oriented CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 L2CAP packet formats Connectionless PDU 2 2 2 bytes length CID=2 PSM payload Connection-oriented PDU 2 2 bytes length CID payload Signalling command PDU 2 2 bytes length CID=1 One or more commands 1 1 2 0 code ID length data CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Security User input (initialization) PIN (1-16 byte) Pairing PIN (1-16 byte) Authentication key generation (possibly permanent storage) E2 E2 link key (128 bit) Authentication link key (128 bit) Encryption key generation (temporary storage) E3 E3 encryption key (128 bit) Encryption encryption key (128 bit) Keystream generator Keystream generator Ciphering payload key payload key Cipher data Data Data CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

SDP – Service Discovery Protocol
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 SDP – Service Discovery Protocol Inquiry/response protocol for discovering services Searching for and browsing services in radio proximity Adapted to the highly dynamic environment Can be complemented by others like SLP, Jini, Salutation, … Defines discovery only, not the usage of services Caching of discovered services Gradual discovery Service record format Information about services provided by attributes Attributes are composed of an 16 bit ID (name) and a value values may be derived from 128 bit Universally Unique Identifiers (UUID) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Additional protocols to support legacy protocols/apps.
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Additional protocols to support legacy protocols/apps. RFCOMM Emulation of a serial port (supports a large base of legacy applications) Allows multiple ports over a single physical channel Telephony Control Protocol Specification (TCS) Call control (setup, release) Group management OBEX Exchange of objects, IrDA replacement WAP Interacting with applications on cellular phones CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 Profiles Applications Represent default solutions for a certain usage model Vertical slice through the protocol stack Basis for interoperability Generic Access Profile Service Discovery Application Profile Cordless Telephony Profile Intercom Profile Serial Port Profile Headset Profile Dial-up Networking Profile Fax Profile LAN Access Profile Generic Object Exchange Profile Object Push Profile File Transfer Profile Synchronization Profile Protocols Additional Profiles Advanced Audio Distribution PAN Audio Video Remote Control Basic Printing Basic Imaging Extended Service Discovery Generic Audio Video Distribution Hands Free Hardcopy Cable Replacement Profiles CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Bluetooth versions Bluetooth 1.1 Bluetooth 1.2
also IEEE Standard initial stable commercial standard Bluetooth 1.2 also IEEE Standard eSCO (extended SCO): higher, variable bitrates, retransmission for SCO AFH (adaptive frequency hopping) to avoid interference Bluetooth EDR (2004, no more IEEE) EDR (enhanced date rate) of 3.0 Mbit/s for ACL and eSCO lower power consumption due to shorter duty cycle Bluetooth EDR (2007) better pairing support, e.g. using NFC improved security Bluetooth HS (2009) Bluetooth EDR + IEEE a/g = 54 Mbit/s CEG436: Mobile Computing (PM)

Mobile Communications 2002 WPAN: IEEE – Bluetooth Data rate Synchronous, connection-oriented: 64 kbit/s Asynchronous, connectionless 433.9 kbit/s symmetric 723.2 / 57.6 kbit/s asymmetric Transmission range POS (Personal Operating Space) up to 10 m with special transceivers up to 100 m Frequency Free 2.4 GHz ISM-band Security Challenge/response (SAFER+), hopping sequence Availability Integrated into many products, several vendors Connection set-up time Depends on power-mode Max. 2.56s, avg. 0.64s Quality of Service Guarantees, ARQ/FEC Manageability Public/private keys needed, key management not specified, simple system integration Special Advantages/Disadvantages Advantage: already integrated into several products, available worldwide, free ISM-band, several vendors, simple system, simple ad-hoc networking, peer to peer, scatternets Disadvantage: interference on ISM-band, limited range, max. 8 active devices/network, high set-up latency CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

WPAN: IEEE 802.15 – future developments 1
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WPAN: IEEE – future developments 1 : Coexistance Coexistence of Wireless Personal Area Networks (802.15) and Wireless Local Area Networks (802.11), quantify the mutual interference : High-Rate Standard for high-rate (20Mbit/s or greater) WPANs, while still low-power/low-cost Data Rates: 11, 22, 33, 44, 55 Mbit/s Quality of Service isochronous protocol Ad hoc peer-to-peer networking Security Low power consumption Low cost Designed to meet the demanding requirements of portable consumer imaging and multimedia applications CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WPAN: IEEE – future developments 2 Several working groups extend the standard a: - withdrawn - Alternative PHY with higher data rate as extension to Applications: multimedia, picture transmission b: Enhanced interoperability of MAC Correction of errors and ambiguities in the standard c: Alternative PHY at GHz Goal: data rates above 2 Gbit/s Not all these working groups really create a standard, not all standards will be found in products later … CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WPAN: IEEE – future developments 3 : Low-Rate, Very Low-Power Low data rate solution with multi-month to multi-year battery life and very low complexity Potential applications are sensors, interactive toys, smart badges, remote controls, and home automation Data rates of kbit/s, latency down to 15 ms Master-Slave or Peer-to-Peer operation Up to 254 devices or simpler nodes Support for critical latency devices, such as joysticks CSMA/CA channel access (data centric), slotted (beacon) or unslotted Automatic network establishment by the PAN coordinator Dynamic device addressing, flexible addressing format Fully handshaked protocol for transfer reliability Power management to ensure low power consumption 16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US ISM band and one channel in the European 868 MHz band Basis of the ZigBee technology – CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 ZigBee Relation to similar to Bluetooth / Pushed by Chipcon (now TI), ember, freescale (Motorola), Honeywell, Mitsubishi, Motorola, Philips, Samsung… More than 260 members about 15 promoters, 133 participants, 111 adopters must be member to commercially use ZigBee spec ZigBee platforms comprise IEEE for layers 1 and 2 ZigBee protocol stack up to the applications CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 WPAN: IEEE – future developments 4 a: Alternative PHY with lower data rate as extension to Properties: precise localization (< 1m precision), extremely low power consumption, longer range Two PHY alternatives UWB (Ultra Wideband): ultra short pulses, communication and localization CSS (Chirp Spread Spectrum): communication only b, c, d, e, f, g: Extensions, corrections, and clarifications regarding Usage of new bands, more flexible security mechanisms RFID, smart utility neighborhood (high scalability) : Mesh Networking Partial meshes, full meshes Range extension, more robustness, longer battery live : Body Area Networks Low power networks e.g. for medical or entertainment use : Visible Light Communication Not all these working groups really create a standard, not all standards will be found in products later … CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Some more IEEE standards for mobile communications
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 Some more IEEE standards for mobile communications IEEE : Broadband Wireless Access / WirelessMAN / WiMax Wireless distribution system, e.g., for the last mile, alternative to DSL 75 Mbit/s up to 50 km LOS, up to 10 km NLOS; 2-66 GHz band Initial standards without roaming or mobility support 802.16e adds mobility support, allows for roaming at 150 km/h IEEE : Mobile Broadband Wireless Access (MBWA) Licensed bands < 3.5 GHz, optimized for IP traffic Peak rate > 1 Mbit/s per user Different mobility classes up to 250 km/h and ranges up to 15 km Relation to e unclear IEEE : Media Independent Handover Interoperability Standardize handover between different 802.x and/or non 802 networks IEEE : Wireless Regional Area Networks (WRAN) Radio-based PHY/MAC for use by license-exempt devices on a non-interfering basis in spectrum that is allocated to the TV Broadcast Service CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

RF Controllers – ISM bands
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RF Controllers – ISM bands Data rate Typ. up to 115 kbit/s (serial interface) Transmission range 5-100 m, depending on power (typ mW) Frequency Typ. 27 (EU, US), 315 (US), 418 (EU), 426 (Japan), 433 (EU), 868 (EU), 915 (US) MHz (depending on regulations) Security Some products with added processors Cost Cheap: 10€-50€ Availability Many products, many vendors Connection set-up time N/A Quality of Service none Manageability Very simple, same as serial interface Special Advantages/Disadvantages Advantage: very low cost, large experience, high volume available Disadvantage: no QoS, crowded ISM bands (particularly 27 and 433 MHz), typ. no Medium Access Control, 418 MHz experiences interference with TETRA CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

RFID – Radio Frequency Identification (1)
Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RFID – Radio Frequency Identification (1) Data rate Transmission of ID only (e.g., 48 bit, 64kbit, 1 Mbit) 9.6 – 115 kbit/s Transmission range Passive: up to 3 m Active: up to m Simultaneous detection of up to, e.g., 256 tags, scanning of, e.g., 40 tags/s Frequency 125 kHz, MHz, 433 MHz, 2.4 GHz, 5.8 GHz and many others Security Application dependent, typ. no crypt. on RFID device Cost Very cheap tags, down to 1€ (passive) Availability Many products, many vendors Connection set-up time Depends on product/medium access scheme (typ. 2 ms per device) Quality of Service none Manageability Very simple, same as serial interface Special Advantages/Disadvantages Advantage: extremely low cost, large experience, high volume available, no power for passive RFIDs needed, large variety of products, relative speeds up to 300 km/h, broad temp. range Disadvantage: no QoS, simple denial of service, crowded ISM bands, typ. one-way (activation/ transmission of ID) CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RFID – Radio Frequency Identification (2) Function Standard: In response to a radio interrogation signal from a reader (base station) the RFID tags transmit their ID Enhanced: additionally data can be sent to the tags, different media access schemes (collision avoidance) Features No line-of sight required (compared to, e.g., laser scanners) RFID tags withstand difficult environmental conditions (sunlight, cold, frost, dirt etc.) Products available with read/write memory, smart-card capabilities Categories Passive RFID: operating power comes from the reader over the air which is feasible up to distances of 3 m, low price (1€) Active RFID: battery powered, distances up to 100 m CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RFID – Radio Frequency Identification (3) Applications Total asset visibility: tracking of goods during manufacturing, localization of pallets, goods etc. Loyalty cards: customers use RFID tags for payment at, e.g., gas stations, collection of buying patterns Automated toll collection: RFIDs mounted in windshields allow commuters to drive through toll plazas without stopping Others: access control, animal identification, tracking of hazardous material, inventory control, warehouse management, ... Local Positioning Systems GPS useless indoors or underground, problematic in cities with high buildings RFID tags transmit signals, receivers estimate the tag location by measuring the signal‘s time of flight CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RFID – Radio Frequency Identification (4) Security Denial-of-Service attacks are always possible Interference of the wireless transmission, shielding of transceivers IDs via manufacturing or one time programming Key exchange via, e.g., RSA possible, encryption via, e.g., AES Future Trends RTLS: Real-Time Locating System – big efforts to make total asset visibility come true Integration of RFID technology into the manufacturing, distribution and logistics chain Creation of „electronic manifests“ at item or package level (embedded inexpensive passive RFID tags) 3D tracking of children, patients CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RFID – Radio Frequency Identification (5) Relevant Standards American National Standards Institute ANSI, Automatic Identification and Data Capture Techniques JTC 1/SC 31, European Radiocommunications Office ERO, European Telecommunications Standards Institute ETSI, Identification Cards and related devices JTC 1/SC 17, Identification and communication ISO TC 104 / SC 4, Road Transport and Traffic Telematics CEN TC 278, Transport Information and Control Systems ISO/TC204, CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 RFID – Radio Frequency Identification (6) ISO Standards ISO 15418 MH Data Identifiers EAN.UCC Application Identifiers ISO Syntax for High Capacity ADC Media ISO Transfer Syntax ISO 18000 Part 2, kHz Part 3, MHz Part 4, 2.45 GHz Part 5, 5.8 GHz Part 6, UHF ( MHz, 433 MHz) ISO RFID Device Conformance Test Methods ISO RF Tag and Interrogator Performance Test Methods CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 ISM band interference OLD Many sources of interference Microwave ovens, microwave lighting 802.11, b, g, , … Even analog TV transmission, surveillance Unlicensed metropolitan area networks … Levels of interference Physical layer: interference acts like noise Spread spectrum tries to minimize this FEC/interleaving tries to correct MAC layer: algorithms not harmonized E.g., Bluetooth might confuse NEW © Fusion Lighting, Inc., now used by LG as Plasma Lighting System CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Mobile Communications 2002 vs.(?) /Bluetooth f [MHz] Bluetooth may act like a rogue member of the network Does not know anything about gaps, inter frame spacing etc. IEEE discusses these problems Proposal: Adaptive Frequency Hopping a non-collaborative Coexistence Mechanism Real effects? Many different opinions, publications, tests, formulae, … Results from complete breakdown to almost no effect Bluetooth (FHSS) seems more robust than b (DSSS) 2480 802.11b 3 channels (separated by installation) 1000 byte ACK 79 channels (separated by hopping pattern) DIFS SIFS DIFS 500 byte ACK 500 byte ACK 500 byte DIFS SIFS DIFS SIFS DIFS 100 byte ACK 100 byte ACK 100 byte ACK 100 byte ACK 100 byte ACK DIFS SIFS DIFS SIFS DIFS SIFS DIFS SIFS DIFS SIFS 2402 t CEG436: Mobile Computing (PM) Prof. Dr.-Ing. Jochen Schiller

Wireless IEEE 802.11 Traditional Bluetooth Infrared

The WiMAX Possibility Wireless & Mobile Broadband at 10-30 miles range

Wireless/Cellular Technologies

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