Existing Wireless System

Existing Wireless System
Azizol Bin Abdullah (A2.04) Rujukan: Text Book Chapter 10

Existing Wireless Systems
Wireless system needs to take many factors into account: Call rate Call duration Distribution of MSs Traffic in an adjacent cell The terrain Atmospheric conditions In the real world, there are various characteristic of existing cellular system and how they support seamless mobile communication

Existing Wireless Systems(cont.)
The important to emphasize in communication system where the receiver gets the information from the sender successfully by following a set of rules call communication protocol. The protocol in a wireless environment also follow similar steps in OSI model, except a few steps are not used for the sake of efficiency. Some layers may be subdivided into a number of successive operations.

Existing Wireless Systems(cont.)
1st Generation 2G G G CDMA, IS95 Verizon, Sprint CDMA-2000 1XRTT CDMA 2000 EV-DO EV-DV AMPS TDMA, IS136 AT&T EDGE? GSM, 1900 MHz Voicestream GSM, 1900/800 MHz AT&T, Cingular WCDMA GPRS NMT, TACS GSM Europe 900/1800 MHz WiFi Bluetooth Wireless Systems

Advanced Mobile Phone Systems(AMPS)
AMPS – first-generation cellular used in US. Transmit speech signal employing FM and control information transmitted in digital using FSK Create by AT&T Bell labs with the idea of dividing the entire service area into logical divisions called cell. Cell radius 1 to 16 miles. Larger cell tends to have more thermal noise and less interference, while smaller cells have more interference and less thermal noise. Allow both cell sectoring and cell spliting.

Advanced Mobile Phone Systems(AMPS) (cont.)
Have low-power MS with 4 Watts or less and medium-power BS with 100 Watts. Capable to support about 100,000 users per city.

AMPS : Characteristic Uses frequency band from 824 MHz to 849 MHz for transmission from MSs to BS(uplink) and 869 MHz to 894 MHz from BS to MSs(downlink) 3 KHz analog voice signal modulated onto 30 KHz channel using Manchester frequency modulation at rate 10 kbps One control transreceiver for every eight voice transreceiver. Frequency allocation done by dividing the entire frequency spectrum into two bands – Band A and Band B.

Non wireline provider are given Band A and wireline provider are given Band B : a total 666 channels. AMPS uses directional radio propagation enables different frequencies to be transmitted in different direction – reducing radio interference.

TACS – Total Access Communication System
variant of AMPS deployed in a number of countries primarily in the UK

NMT – Nordic Mobile Telephone System
analog technology deployed in the Benelux countries and Russia operates in the 450 and 900 MHz band first technology to offer international roaming – only within the Nordic countries

Global System for Mobile Communication (GSM) : Introduction
Early 80’s Europe was experiencing rapid growth in the analog cellular telephone systems 1982 Conference of European Posts and Telegraphs (CEPT) GSM (Groupe Special Mobile) group was formed to study and develop a pan-European public land mobile system GSM mandate was to develop a standard to be common for the countries that created it – provide service to the entire European continent

Global System for Mobile Communication (GSM) : Introduction. (cont.)
GSM criteria – Good subjective speech quality Low terminal and service cost Support for international roaming – one system for all of Europe Ability to support handheld terminals Support for range of new services and facilities Enhanced Features ISDN compatibility Enhance privacy Security against fraud

Global System for Mobile Communication (GSM) : Introduction. (cont.)
Phase I of GSM specifications was published in 1990 International demand was so great that the system name was changed from Groupe Special Mobile to Global Systems for Mobile Communications (still GSM) Commercial service started in mid-1991 1992 first paying customers were signed up for service By 1993 there were 36 GSM networks in 22 countries Early 1994 there were 1.3 million subscribers worldwide By 1996 there were more than 25 million subscribers worldwide By October 1997 it had grown to more than 55 million subscribers worldwide

GSM : System Architecture
Mobile Station (MS) Mobile Equipment (ME) Subscriber Identity Module (SIM) Base Station Subsystem (BBS) Base Transceiver Station (BTS) Base Station Controller (BSC) Network Subsystem Mobile Switching Center (MSC) Home Location Register (HLR) Visitor Location Register (VLR) Authentication Center (AUC) Equipment Identity Register (EIR)

GSM : System Architecture (cont.)

The Mobile Station is made up of two entities: 1. Mobile Equipment (ME) Produced by many different manufacturers Must obtain approval from the standardization body Uniquely identified by an IMEI (International Mobile Equipment Identity) 2. Subscriber Identity Module (SIM) Smart card containing the International Mobile Subscriber Identity (IMSI) Allows user to send and receive calls and receive other subscribed services Encoded network identification details Protected by a password or PIN Can be moved from phone to phone – contains key information to activate the phone

Base Station Subsystem is composed of two parts that communicate across the standardized Abis interface allowing operation between components made by different suppliers Base Transceiver Station (BTS) Base Station Controller (BSC)

Base Transceiver Station (BTS) Houses the radio transceivers that define a cell Handles radio-link protocols with the Mobile Station Speech and data transmissions from the MS are recoded Requirements for BTS: reliability portability minimum costs

Base Station Controller (BSC) Manages Resources for BTS Handles call set up Location update Handover for each MS

Mobile Switching Center (MSC) Switch speech and data connections between: Base Station Controllers Mobile Switching Centers GSM-networks Other external networks Heart of the network Three main jobs: 1) connects calls from sender to receiver 2) collects details of the calls made and received 3) supervises operation of the rest of the network components

Home Location Registers (HLR) - contains administrative information of each subscriber - current location of the mobile Visitor Location Registers (VLR) - contains selected administrative information from the HLR authenticates the user tracks which customers have the phone on and ready to receive a call periodically updates the database on which phones are turned on and ready to receive calls

Authentication Center (AUC) mainly used for security data storage location and functional part of the network Ki is the primary element Equipment Identity Register (EIR) - Database that is used to track handsets using the IMEI (International Mobile Equipment Identity) Made up of three sub-classes: The White List, The Black List and the Gray List Optional database

GSM : Features Call Waiting Call Hold Call Barring Call Forwarding
- Notification of an incoming call while on the handset Call Hold - Put a caller on hold to take another call Call Barring - All calls, outgoing calls, or incoming calls Call Forwarding - Calls can be sent to various numbers defined by the user Multi Party Call Conferencing - Link multiple calls together

GSM : Advance Features Calling Line ID Alternate Line Service
- incoming telephone number displayed Alternate Line Service - one for personal calls - one for business calls Closed User Group - call by dialing last for numbers Advice of Charge - tally of actual costs of phone calls Fax & Data - Virtual Office / Professional Office Roaming - services and features can follow customer from market to market

GSM: Advantages Crisper, cleaner quieter calls
Security against fraud and eavesdropping International roaming capability in over 100 countries Improved battery life Efficient network design for less expensive system expansion Efficient use of spectrum Advanced features such as short messaging and caller ID A wide variety of handsets and accessories High stability mobile fax and data at up to 9600 baud Ease of use with over the air activation, and all account information is held in a smart card which can be moved from handset to handset

GSM : Frequency Band and Channels
Allocated an operational frequency from 890 MHz to 960 MHz. To reduce interference – MS and BS used different frequency range MSs : 890 MHz to 915 MHz BS : 935 MHz to 960 MHz GSM follows FDMA and allows up to 124 MSs to be serviced at the same time. 25 MHz frequency is divided into 124 FDM channels( each 200 kHz, guard frame 8.25 bits)

GSM : Frequency Band and Channels (cont.)
Uses a variety of control channels – ensure uninterrupted communication between MSs and BS. Three control channels used for broadcasting info to all MSs: Broadcast Control Channel (BCCH) : transmitting system parameters – frequency of operation in the cell and operator identifiers Frequency Correction Channel (FCCH) : transmitting frequency references & frequency correction burst at 148 bits length Synchronization Channel (SCH) : provide the synchronization training sequences burst of 64 bits length to MSs

Three control channels used for establishing links and ongoing call management: Random Access Channel (RACH) : used by the MS to transmit information regarding the requested dedicated channel from GSM. Paging Channel : used by the BS to communicate with individual MSs in the cell. Access Grant Channel : Used by the BS to send information about timing and synhronization

Dedicated control channels used along with traffic channels to serve for any control information transmission during the actual communication: Slow Associated Control Channel (SACCH): Allocated along with a user channel, for transmission of control information during the actual transmission. Stand-alone Dedicated Control Channel (SDCCH): Allocated with SACCH – used to transfer of signaling information between BS and MSs – part of control channel. Fast Associated Control Channel (FACCH): carries the same information as SDCCH - part of traffic channel. Facilitate FACCH to steak certain bursts from the traffic channels –flag bits (two bits) in the message.

Personal Communication Services (PCS)
Employs an inexpensive, lightweight and portable handset to communicate with a PCS BS. PCS encompasses the whole spectrum of communication services : an ordinary telephone to cable television. PCS can be classified into: high-tier and low-tier standards. Higher-tier systems include high-mobility units with large batteries. Low-tier systems include systems with low mobility, capable of providing high-quality portable communication services over a wide area. PCS low-tier standards based on PACS (Personal Access Communication System) and DECT (Digital European Cordless Telecommunications)

PCS : Chronology of PCS Development
Start with CT2 – cordless telephone Operates using FDMA with the speech rate of 32 kbps using Adaptive Differential Pulse Code Modulation (ADPCM). Transmitter data rate 72 kbps Uses TDD, allows BS and MS to share one channel DECT 2nd generation cordless telephone system. Operates on frequencies ranging from 1880 MHz to 1900 MHz Uses ADPCM with 32 kbps Uses TDD with 2 frames (BS-MS, MS-BS) 10-ms period

PCS : Bellcore view of PCS
Based on 5 different access services between BCC( Bellcore client company), BCC network and PCS wireless provider: PCS access services for network (PASN) – connection to and from PCS service provider. PCS access service for controller (PASC) – uses across radio channel and automatic link transfer capability PCS access service for ports (PASP) – interface to PCS wireless provider PCS access service for Data (PASD) – database information transport service PCS access service for external service provider (PASE) – support specialized service like voice mail and paging.

IS-95 Interim Standard 95 (IS-95), is the first CDMA-based
digital cellular standard pioneered by Qualcomm(wireless telecommunication R&D company based in USA) Its brand name is cdmaOne and the initial specification for the system was IS95A, but its performance was later upgraded under IS-95B. Apart from voice the mobile phone system is also able to carry data at rates up to 14.4 kbps for IS-95A and 115 kbps for IS-95B.

IS-95 (cont.) Qualcomm had been investigating the use of direct sequence spread spectrum techniques for military use when it was realised that it could be used as a multiple access technology for mobile communications. - It is now being supplanted by IS-2000 or better known as cdma2000.

IS-136 The name "TDMA" is used to refer to a specific second generation mobile phone standard - more properly referred to as IS-136, which uses the TDMA technique to timeshare the bandwidth of the carrier wave. It provides between 3 to 6 times the capacity of its predecessor AMPS, and also improved security and privacy. - In the United States, for example, AT&T Wireless uses the IS-136 TDMA standard. Prior to the introduction of IS-136, there was another TDMA North American digital cellular standard called IS-54(which was also referred to just as "TDMA").

GPRS a radio technology for GSM networks that adds packet-switching protocols, shorter set-up time for ISP connections, and offer the possibility to charge by amount of data sent rather than connect time. GPRS promises to support flexible data transmission rates typically up to 20 or 30 Kbps (with a theoretical maximum of Kbps), as well as continuous connection to the network. A 2.5G enhancement to GSM, GPRS is the most significant step towards 3G, needing similar business model, and service and network architectures. GPRS started to appear in some networks during 2000.

EDGE -Enhanced Data Rates for GSM Evolution:
An enhanced modulation technique designed to increase network capacity and data rates in GSM networks. EDGE should provide data rates up to 384 Kbps. EDGE will let operators without a 3G license to compete with 3G networks offering similar data services.

IMT2000 IMT-2000 (International Mobile Telecommunications-2000) is the standards for the "third generation" (3G) mobile phone services which enables high speed, high quality multi-media voice and data transmission through cellular phone system. (a generic way to describe third-generation cellular phone services that offer high-speed Internet access.) -It enables global service IMT-2000 uses a 2 GHz frequency band which is allocated to all the countries. Thus it enable the global service of high speed communications interoperable in all countries.

IMT2000(cont) ITU approved 5 terresterial and 6 satellite based systems Various new standards have been proposed and alliances formed to promote 3G wireless standards. Japan and Europe jointly proposed Wideband CDMA (or W-CDMA) standard,and U.S. proposed CDMA2000 and many others. In November 1999, ITU-R SG8 approved 5 terresterial systems (including W-CDMA and CDMA2000) and 6 satellite-based systems for IMT-2000.

UMTS UMTS (Universal Mobile Telecommunications System) is the European vision of a third generation mobile communication system. It is designed to continue the global success of the European second generation mobile communication system GSM (Global System for Mobile communication) which had, in December 1998, about 100 million customers and 300 operators worldwide. -3GPP developed the specification for UMTS. The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that was established in December 1998

UMTS (cont) Network Development:
The development of UMTS has got two aspects, the radio access network and the core network. The radio access network comprises the mobile station (handy), the base station (transceiver, antenna, controller) and the radio interface between them. The core network consists of nodes (switches) with connecting lines. This core network does not only connect the base stations with each other but offers also gateways to other networks (ISDN, Internet,..) The core network of UMTS is an evolution of the present GSM-core network. The radio access network of UMTS, especially the method of radio transmission (radio interface), is revolutionary new. The UMTS radio access network URAN will not be an evolution of the GSM radio access network. However, the GSM radio access network will be in use and also under development even after the introduction of UMTS. This means that there will be a common core network but two independent radio access networks for UMTS and for GSM. The UMTS radio access network will allow for multimedia applications because of the larger bandwidth of the radio channels (5 MHz instead of 200 kHz in GSM) and the new access method CDMA (Code division multiple access).

UMTS (cont) Network development(cont)
Multimedia in UMTS means that the simultaneous transfer of speech, data, text, pictures, audio and video with a maximum data rate of 2 Mbit/s will be possible. Transmission of speech and low data rate applications will go on to be carried out by GSM (lower price); at least during the first years after the introduction of UMTS around 2002.

UMTS (cont) Hierarchical cell structure
fig. 1: Hierarchical cell structure of UMTS to offer global radio coverage UMTS will offer global radio coverage and world-wide roaming. For that purpose the URAN will be built in a hierarchical way in layers of varying coverage. A higher layer will cover a larger geographical area than a lower layer. In the highest layer there will be satellites covering the whole planet, the lower layers form the UMTS terrestrial radio access network UTRAN. They are divided into macro-, micro- and picolayer. Each layer is divided into cells. The lower the hierarchical level, the smaller the cells. Smaller cells allow for a higher user-density. Therefore macrocells are used for land-wide coverage, additional microcells are installed in areas with higer population density and picocells in buildings and for so called "hot spots" (e.g. airports, railway stations).

UMTS (cont) fig. 2: Data rate versus mobility for UMTS in comparison with fixed network and other mobile communications systems (WLAN Wireless Local Area Network, MBS Mobile Broadband Systems) Data rate The maximum data rate and the maximum speed of the user are different in each hierarchical layer. In the macrolayer at least 144 kbit/s with maximum speed of 500 km/h shall be possible. In the microlayer 384 kbit/s with maximum speed of 120 km/h shall be supported. The picolayer offers up to 2 Mbit/s with a maximum speed of 10 km/h. It shall be possible for the user to trade off bit error rate versus delay in certain limits. For real-time applications with constant delay (speech, video) the bit error rate can be in the range of 10-3 to 10-7, the maximum delay can be in the range of 20 ms to 300 ms. For non-realtime applications ( , SMS) with variable delay the bit error rate can be in the range of 10-5 and The maximum delay can be 150 ms and more.

UMTS (cont) Spectrum fig. 3: Spectrum for UMTS - 1920 MHz MHz FDD Uplink 2110 MHz MHz FDD Downlink 1900 MHz MHz TDD 2010 MHz MHz 1980 MHz MHz MSS (Mobile Satellite Service) Uplink 2170 MHz MHz MSS Downlink The spectrum for UMTS lies between 1900 MHz to 2025 MHz and 2110 MHz to 2200 MHz. For the satellite service an own subband in the UMTS spectrum is reserved (uplink 1980 MHz to 2010 MHz, downlink 2170 MHz to 2200 MHz). The remaining spectrum for terrestrial use is divided between two modes of operation. In the FDD (Frequency Division Duplex) mode there are two equal bands for the uplink (1920 MHz to 1980 MHz) and for the downlink (2110 MHz to 2170 MHz). In the operation mode TDD (Time division duplex) uplink and downlink are not divided by use of different frequency carriers but by using different timeslots on the same carrier. So there is no need for a symmetrical spectrum but the remaining unpaired spectrum can be used.

cdma2000 CDMA2000 - A third-generation wireless technology proposal
submitted to the International Telecommunication Union, which is based on the IS-95, or cdmaOne, standard. -CDMA2000 specification was developed by the Third Generation Partnership Project 2 (3G PP2), a partnership consisting of five telecommunications standards bodies: ARIB and TTC in Japan, CWTS in China, TTA in Korea and TIA in North America. Cdma2000 has already been implemented to several networks as an evolutionary step from cdmaOne.

cdma2000 (cont.) The first 3G networks to be commercially deployed were launched in Korea in October 2000 using CDMA2000 technology. CDMA2000 dominates the 3G market today and analysts forecast that it will continue to lead in the future.

cdma2000 (cont.) CDMA2000 Common name for IMT-2000 CDMA Multi-Carrier.
CDMA2000 1X The first step in the evolution to 3G is cdma2000 1X, which improves packet data transmission capabilities and speeds in the network, and also boosts voice capacity by nearly two times over today's CDMA capacities. Speed of upto 144kpps. CDMA2000 1xEV-DO (Evolution Data-Only). CDMA2000 1XEV represents the second step in the evolution of CDMA2000. Commercially launched in 2001, offers data speeds of up to 2.4 Mbps on a separate 1.25 MHz carrier. CDMA2000 1xEV-DV (Evolution Data-Voice). CDMA2000 1XEV represents the second step in the evolution of CDMA2000. Recently approved by ITU as a 3G technology, will provide data and voice together on a single 1.25 MHz channel, with data rates of up to 4.8 Mbps. CDMA2000 3X 3G technology which offers voice and data on a 5MHz carrier (or 3 times [3X] the 1.25 MHz carrier). Full 3G version of CDMA2000. Technology is similar to CDMA2000 1x, but the peak data rate is 2Mbps.

Migration Paths to 3G (USA Environment)
AMPS IS-54 IS-136 IS-95 EDGE cdma2000 1x 3G cdma2000 3x NOTE: IS-54:the GSM TDMA IS-136: the D-AMPS(different TDMA) IS-95: the cdmaOne The version of this CDMA is incompatible with the one used in Europe, known as WCDMA!!!

Migration Paths to 3G (Europe Environment)
NMT (Scandinavia) GSM GPRS EDGE UMTS TACS (England) UMTS: Universal Mobile Telecommunications Systems, the “official” 3G system for Europe. UMTS is a true packet switched network(no more overlay). However, it works at different frequency(2000 MHz) than both 1G and 2G, thus major upgrade required. UMTS is not based on TDMA like GSM but on CDMA called the Wideband CDMA/WCDMA.

Migration Paths to 3G (Japan Environment)
JTACS PDC WCDMA PDC is based on TDMA air interface. Because of all this uniformity, it was possible for Japan to jump over 2.5G and go right to 3G system. As a result, Japan is the 1st country to deploy a system with 3G capabilities. The system is based on a WCDMA air interface similar to that in UMTS.

Migration Paths to 3G (Summary)
AMPS IS-54 IS-136 IS-95 EDGE cdma2000 1x 3G cdma2000 3x GSM NMT TACS EDGE UMTS GPRS (Scandinavia) (England) PDC JTACS WCDMA

Summary

Worldwide Systems Acronym System Where First Deployed Technology AMPS
Advanced Mobile Phone Service USA Analog CDMA Code Division Multiple Access Digital D-AMPS Digital Advanced Mobile Phone Service DCS1800 Digital Communication Service Germany & England GSM Group Special Mobile 80 European countries JTACS Japan Total Access Communication System Japan

Worldwide Systems(cont)
Acronym System Where First Deployed Technology NADC North American Digital Cellular USA Digital NMT Nordic Mobile Telephone Scandinavian countries Analog PCS1900 Personal Communication Services PDC Personal Digital Cellular Japan SMR Specialized Mobile Radio Both TACS Total Access Communications System England

Characteristics of Various Cellular Generations
Signal Type Analog Digital Switching Circuit Packet Offerings Voice Messaging Internet Multimedia Data Rate - 14 Kbps 144 Kbps 384 Kbps – 2Mbps

First Generation started appearing in the 1980s
1G networks are based on the AMPS (Advanced Mobile Phone Service) standard 1G introduced the idea of cells analog (varying waveform in sending info) and not digital only to be used for voice communication; no data service quality was not that good(a lot of interference)

First Generation (cont.)
disadvantages: a) insecure i) one can snoop into other people’s conversation ii) can charge calls to another person’s account b) Handsets had short talk/standby times

Second Generation converts all voice communication into digital ( 0 and 1 only) there are several 2G standards in use: i) TDMA (Time Division Multiple Access). Used primarily in the USA. ii)GSM (Global System for Mobile Communications). Widely used in Europe and countries other than USA, now appearing in the USA.

Second Generation (cont.)
iii)CDMA (Code Division Multiple Access). Used in USA and its use is spreading in the rest of the world. iv)PDC (Personal Digital Cellular). Used only in Japan where iMode uses packet switched PDC.

Second Generation (cont)
-some characteristics of 2G networks are: #Maximum data rates of 9.6 to 14.4 Kbits/second #Digital voice(results in a lower quality voice but uses less precious spectrum) #Enhanced telephony features such as caller-id. #Services such as text based messaging (big winner), downloads of still images and audio clips, etc. #Much secure; encryption

2.5 Generation are essentially General Packet Radio Service (GPRS)
packet overlays on 2G networks. Besides enhancing GSM and TDMA networks by making them packet-based networks, it also increases their data rates. it is primarily a software upgrade of GSM. some characteristics of 2.5G networks are: #Data rates of kb/second. #Packet based. #Always-on connectivity. #Instant messaging with small attachments.

2.5 Generation (cont) A new wireless standard, Enhanced Data GSM Environment (EDGE), has been developed to increase the bandwidth of GPRS. -EDGE triples the bandwidth capacity of GPRS to 384 Kbits/second thus allowing GSM and TDMA operators to offer high-speed services. EDGE based networks fall in between 2.5G and 3G networks. (

Third Generation -3G provides high speed bandwidth (high data transfer rates) to handheld devices. Specifically, 3G wireless networks support the following maximum data transfer rates: 2.05 Mbits/second to stationary devices. 384 Kbits/second for slowly moving devices, such as a handset carried by a walking user. 128 Kbits/second for fast moving devices, such as handsets in moving vehicles.

Third Generation (cont.)
It is expected that 3G will be able to offer a variety of new services that combine high voice quality telephony, high-speed Mobile IP services, information technology, rich media, and offer diverse content.

Fourth Generation -4G networks are already in the labs, targeted for deployment beginning in 2010 will provide up to 100 Mbps one possible application for such high data rates is telepresence (a virtual reality: full stimulation of all senses required to provide the illusion of actually being somewhere else AKA an illusion that cannot be distinguished from the real thing!!) (Referance: Andy Dornan, The Essential Guide to Wireless Communications Applications, Prentice Hall 2001)

Fourth Generation

“Killer” Applications
-Two 2G wireless data applications have turned out to be big winners: iMode (Japan): Downloading of images to mobile phones and forwarding them to other mobile phones. b)GSM (Europe and countries other than USA): Sending short text messages from one mobile phone to another using the Short Message Service (SMS)

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