WIRELESS AND MOBILE COMMUNICATION A M BALAMURUGAN Syllabus

WIRELESS AND MOBILE COMMUNICATION A. M. BALAMURUGAN

Syllabus Overview Ø Ø Ø Introduction to Wireless Systems and Cellular Concepts Signal Propagation through the channel Advanced processing techniques Signal enhancement techniques Wireless Standards

Wireless networks vs wired networks Media Reliability (Bit Error Probability) Wired Wireless ~ 10 -9 10 -2 ~ 10 -6 Almost Mobility stationary System Capacity Mbit/s, Gbit/s, Tbit /s Various mobility 20 Mbit/s (2 Mbit/s) (expensive) • Negative: unreliable, low capacity, expensive. • Positive: wireless, mobility.

Electromagnetic spectrum Gamma rays -8 -7 -6 Cosmic rays Long Electrical Oscillations Ultraviolet Visible lights -4 X-rays -2 -1 0 Infrared 3 6 Microwaves 10 Radiowaves (wavelength in 10 x micrometer) - Robert J. Hoss et al, “Fiber Optics”, ISBN 0133212416, Prentice-Hall, 1993, pp 24. 11

Communication Frequencies twisted pair coax cable 10 km 30 k. Hz VLF LF optical transmission 100 m 3 MHz MF HF 1 m 300 MHz VHF UHF 10 mm 30 GHz SHF EHF 100 m 3 THz 1 m 300 THz infrared Frequency and wave length: = c/f wave length , speed of light c 3 x 108 m/s, frequency f visible light UV

Frequencies for mobile communication n VHF-/UHF-ranges for mobile radio n n n SHF and higher for directed radio links, satellite communication n simple, small antenna for cars deterministic propagation characteristics, reliable connections small antenna, focusing large bandwidth available Wireless LANs use frequencies in UHF to SHF spectrum n n some systems planned up to EHF limitations due to absorption by water and oxygen molecules (resonance frequencies) n weather dependent fading, signal loss caused by heavy rainfall etc.

Media used for wireless networks • The range that can be used by WN is only a fraction of the electromagnetic spectrum: Infrared, Microwaves and Radio-waves. • Wireless network is a sort of shared-media network. The wireless terminals belonging to the same network will share one wireless media (i. e. , air interface). • Wireless media/spectra is a scare resource.

Multiple access schemes How to allow many wireless terminals to share a finite amount of radio spectrum simultaneously? Ø Fixed Access Ø Random Access - T. S. Rappaport, “Wireless communications, principles & practice”, ISBN 0133755363, Prentice-Hall, 1996, pp 395 -438.

Fixed access schemes • Time Division Multiple Access (TDMA): Radio spectrum is divided into time slots, and each slot is used by only one user (e. g. , GSM, JDC). • Frequency Division Multiple Access (FDMA): Radio spectrum is divided into sub-frequency band (channel), and each channel is used by only one user (e. g. , CT 2, DECT). • Code Division Multiple Access (CDMA): Part/entire spectrum/time alloted to user differentiated by appropriate coding ( e. g. 3 rd generation of wireless networks). - T. S. Rappaport, “Wireless communications, principles & practice”, ISBN 0133755363, Prentice-Hall, 1996, pp 395 -438.

Multi-Access Radio Techniques Courtesy of Petri Possi, UMTS World

CDMA Courtesy of Suresh Goyal & Rich Howard

Courtesy of Suresh Goyal & Rich Howard

Courtesy of Suresh Goyal & Rich Howard

Courtesy of Suresh Goyal & Rich Howard

Random access schemes 1. Contention-based: Aloha, CSMA. 2. Controlled-based: - Central control (Polling); - Distributed control (Token-ring). • Aspects: application requirements, cost and feasible network topology etc. • Performance: resource utilization, throughput, fairness and network robustness etc.

Duplexing technologies ØDuplexing enables mobile users to send and receive (talk / listen) “simultaneously”: Forward channel (downlink) Base-station Reverse channel (uplink) Mobile ü Frequency division duplex (FDD): use two distinct band of frequencies for every user expensive duplexers ü Time division duplex (TDD): use two different time slots for every user not true full duplex - T. S. Rappaport, “Wireless communications, principles & practice”, ISBN 0133755363, Prentice-Hall, 1996, pp 395 -396.

Wireless Communication System - Definitions n n n Base Station, Mobile Station Control / Traffic channels Mobile Switching Center Paging Roamer Handoff

First Mobile Radio Telephone 1924 Courtesy of Rich Howard

WIRELESS DATA VISION Region TAXI City laptops, PDAs Campus In-Building Seamless Multimedia Networks with Mobility and Freedom from Tethers [R. Katz, "Does Wireless Data Have a Future? ", Plenary Talk, INFOCOM '96] 8 C 32810. 35 -Cimini-7/98

IMT-2000 Vision Includes LAN, WAN and Satellite Services Global Satellite Suburban Macrocell Urban Microcell Basic Terminal PDA Terminal Audio/Visual Terminal In-Building Picocell

Cellular networks: Development Ø First generation: ØBased on analog technology, uses a single base station to communicate with a single portable terminal. (e. g. , Advance Mobile Phone Services - AMPS) Ø Second generation: ØBased on digital modulation and advanced call processing capabilities. (e. g. , Global System for Mobile - GSM and Cordless Telephone - CT 2). Ø Third generation: ØTo provide a single set of standards that can meet a wide range of wireless applications and provide universal access throughout the world. (e. g. , WCDMA, CDMA-2000, etc. ) - T. S. Rappaport, “Wireless communications, principles & practice”, ISBN 0133755363, Prentice-Hall, 1996, pp 445 -449.

First Generation n Advanced Mobile Phone Service (AMPS) n US trials 1978; deployed in Japan (’ 79) & US (’ 83) n 800 MHz band — two 20 MHz bands n TIA-553 n Still widely used in US and many parts of the world Nordic Mobile Telephony (NMT) n Sweden, Norway, Demark & Finland n Launched 1981; now largely retired n 450 MHz; later at 900 MHz (NMT 900) Total Access Communications System (TACS) n British design; similar to AMPS; deployed 1985 n Some TACS-900 systems still in use in Europe

1 G — Separate Frequencies FDMA — Frequency Division Multiple Access 30 KHz Frequency 30 KHz 30 KHz

Second Generation — 2 G n n n Digital systems Leverage technology to increase capacity n Speech compression; digital signal processing Utilize/extend “Intelligent Network” concepts Improve fraud prevention Add new services There a wide diversity of 2 G systems n IS-54/ IS-136 North American TDMA; PDC (Japan) n i. DEN n DECT and PHS n IS-95 CDMA (cdma. One) n GSM

D-AMPS/ TDMA & PDC n n n Speech coded as digital bit stream n Compression plus error protection bits n Aggressive compression limits voice quality Time division multiple access (TDMA) n 3 calls per radio channel using repeating time slices Deployed 1993 (PDC 1994) n Development through 1980 s; bakeoff 1987 IS-54 / IS-136 standards in US TIA ATT Wireless & Cingular use IS-136 today n Plan to migrate to GSM and then to W-CDMA PDC dominant cellular system in Japan today n NTT Do. Co. Mo has largest PDC network

i. DEN n n Used by Nextel Motorola proprietary system n Time division multiple access technology n Based on GSM architecture 800 MHz private mobile radio (PMR) spectrum n Just below 800 MHz cellular band Special protocol supports fast “Push-to-Talk” n Digital replacement for old PMR services

2 G — TDMA Time Division Multiple Access One timeslot = 0. 577 ms One TDMA frame = 8 timeslots Frequency 200 KHz Time

DECT and PHS n n n Also based on time division multiple access Digital European Cordless Telephony n Focus on business use, i. e. wireless PBX n Very small cells; In building propagation issues n Wide bandwidth (32 kbps channels) n High-quality voice and/or ISDN data Personal Handyphone Service n Similar performance (32 kbps channels) n Deployed across Japanese cities (high pop. density) n 4 channel base station uses one ISDN BRI line n Base stations on top of phone booths

GSM n n n « Groupe Special Mobile » , later changed to « Global System for Mobile » n Joint European effort beginning in 1982 n Focus on seamless roaming across Europe Services launched 1991 n Time division multiple access (8 users per 200 KHz) n 900 MHz band; later extended to 1800 MHz n Added 1900 MHz (US PCS bands) GSM is dominant world standard today n Well defined interfaces; many competitors n Tri-band GSM phone can roam the world today

Distribution of GSM Subscribers n n GSM is used by 70% of subscribers worldwide n 564 M subs / 800 M subs in July 2001 Most GSM deployments in Europe (59%) and Asia (33%) Source: EMC World Cellular / GSM Association

North American CDMA (cdma. One) n Code Division Multiple Access n n n Qualcomm demo in 1989 n n n All users share same frequency band CDMA is the basis for 3 G networks Claimed improved capacity & simplified planning First deployment in Hong Kong late 1994 Major success in Korea (1 M subs by 1996) Used by Verizon and Sprint in US Simplest 3 G migration story today

cdma. One — IS-95 n n TIA standard IS-95 (ANSI-95) in 1993 IS-95 deployed in the 800 MHz cellular band n n Evolution fixes bugs and adds data n n J-STD-08 variant deployed in 1900 MHz US “PCS” band IS-95 A provides data rates up to 14. 4 kbps IS-95 B provides rates up to 64 kbps (2. 5 G) Both A and B are compatible with J-STD-08 All variants designed for TIA IS-41 core networks (ANSI 41)

2 G & 3 G — CDMA Code Division Multiple Access n n n Spread spectrum modulation n Originally developed for the military n Resists jamming and many kinds of interference n Coded modulation hidden from those w/o the code All users share same (large) block of spectrum n One for one frequency reuse n Soft handoffs possible Almost all accepted 3 G radio standards are based on CDMA 2000, W-CDMA and TD-SCDMA

Other Wireless Systems n Paging Systems n n Simplex Limited to worldwide coverage possible Broadcast / simulcast Reliable large Txd. Power, Low data rate Paging towers PSTN Paging Control center Paging towers

Other Wireless Systems n Cordless telephone systems n n n Dedicated Base Station Limited coverage No handoff support PSTN Fixed Base Station

A general WLL setup

Satellite networks: GEO Japan Gateway Public networks Control station GEO Singapore Gateway Control station Public networks

Satellite networks: LEO Japan LEO Gateway Public networks Control station Singapore LEO Inter-satellite link Gateway Control station Public networks

Satellite networks: Comparison LEO MEO GEO Satellite cost (unit) Minimum Medium Maximum Satellite life (year) 3 -7 10 -15 Hand-held terminal Possible Very Difficult Propagation delay Short Medium Large Propagation loss Low Medium High Network complexity Complex Medium Simple Hand-off Very Medium No Development period Long Short Long Visibility of satellite Short Medium Always -A. Jamalipour, “Low Earth Orbital Satellites for Personal Communication Networks”, ISBN 0890069557, Artech-House, 1998, pp 17.

Satellite networks: Orbit altitude GEO 35, 786 (km) MEO LEO 10, 000~ 20, 000 >1, 500 GEO=Geostationary EO MEO=Medium EO LEO=Low EO EO=Earth Orbit -A. Jamalipour, “Low Earth Orbital Satellites for Personal Communication Networks”, ISBN 0890069557, Artech-House, 1998, pp 15.

Ad-hoc networks -Nodes can communicate each other directly without needing a central co-ordination, and move arbitrarily during communication. -http: //www. ericsson. se/Review/er 3_98/art 1. html

STANDARDS AND FUTURE SYSTEMS • Bluetooth • Wireless LANs • High-Speed Digital Cellular (3 G) • 4 G Cellular • Wireless "Cable" – Multichannel Multipoint Distribution Service (2. 2 GHz) – Local Multipoint Distribution Service (28 GHz) • Satellite Networks - Iridium, Globalstar, Others • Home. RF 8 C 32810. 61 -Cimini-7/98

Bluetooth A new global standard for data and voice Cable replacement RF technology • Short range (10 meters) • 2. 4 GHz band • 1 Data (700 Kbps) and 3 Voice channels • Supported by over 200 telecommunications and computer companies Goodbye Cables !

Ultimate Headset

Cordless Computer

Automatic Synchronization In the Office At Home

Bluetooth Specifications Connection Type Spread Spectrum (Frequency Hopping) MAC Scheme FH-CDMA Spectrum 2. 4 GHz ISM Modulation Gaussian Frequency Shift Keying Transmission Power 1 mw – 100 mw Aggregate Data Rate 1 Mbps Range 30 ft Supported Stations 8 devices Voice Channels 3 Data Security- Authentication Key 128 bit key Data Security-Encryption Key 8 -128 bits (configurable)

802. 11 Wireless LANs • 802. 11 b: standard for 2. 4 GHz ISM band • Frequency hopped spread spectrum • 1. 6 Mbps data rates, 500 foot range • Star or peer-to-peer architecture • 802. 11 a extends rates to 10 -70 Mbps • Extensions trying to add Qo. S 8 C 32810. 63 b-Cimini-7/98

Wireless LAN IEEE 802. 11 a/b/g/h/j/n • b • a • g • h • j • n : : : 1999 2002 – 2003 – 2004 2006 ~2. 4 GHz ISM ~5. 0 GHz ISM

Modulation & Filter type • b DBPSK / DQPSK ( 11 Mbps ) Gaussian filter or vendor specific • a/g/h/j upto 64 QAM on 52 OFDM subcarriers, rectangular filter or vendor specific (54 Mbps ) • n upto 64 QAM on 108 OFDM subcarriers, rectangular filter or vendor specific ( yet to be defined )

HIPERLAN • Types 1 -4 for different user types - Frequency bands: 5. 15 -5. 3 GHz, 17. 1 - 17. 3 GHz • Type 1 - 5. 15 -5. 3 GHz band - 23 Mbps, 20 MHz Channels - 150 foot range (local access only) - Protocol support similar to 802. 11 - Peer to peer architecture - ALOHA channel access • Types 2 -3 - Wireless ATM - Local access and wide area services - Standard under development - Two components: access and mobility support 8 C 32810. 63 a-Cimini-7/98

HIGH-SPEED DIGITAL CELLULAR • North American Digital Cellular – CDMA (IS-95) enhancements – TDMA (IS-136) enhancements – IS-136+ Þ 32 -64 kbps – IS-136 HS Þ 384 kbps • GSM – General Packet Radio System (GPRS) – Enhanced Data Rates for GSM Evolution (EDGE) 8 C 32810. 62 -Cimini-7/98

EDGE • Evolution of GSM / GPRS • ETSI standardization as GSM evolution chosen for data services for IS 136 HS • Higher-level modulation (adaptive) • 200 k. Hz carrier spacing • Up to 384 kbps in 200 k. Hz 8 C 32810. 137 ppt-Cimini-7/98

WIDEBAND CDMA (3 G) • The W-CDMA concept: – 4. 096 Mcps Direct Sequence CDMA – Variable spreading and multicode operation – Coherent in both up-and downlink = Codes with different spreading, giving 8 -500 kbps . . P f 4. 4 -5 MHz t High rate multicode user 8 C 32810. 138 ppt-Cimini-7/98 Variable rate users 10 ms frame

W-CDMA KEY TECHNICAL FEATURES • High bit-rate services require wideband • Flexibility for different services • Optimized for packet data transfer • Capacity and coverage gain from frequency diversity • Built in support for – adaptive antenna arrays – multi-user detection – hierarchical cell structures – transmitter diversity • Low infrastructure cost (many users/ transceiver) • BS synchronization not required 8 C 32810. 139 ppt-Cimini-7/98

Spectral Allocation

3 G Vision n Universal global roaming Multimedia (voice, data & video) Increased data rates n n n 384 kbps while moving 2 Mbps when stationary at specific locations Increased capacity (more spectrally efficient) IP architecture Problems n n No killer application for wireless data as yet Vendor-driven

Migration To 3 G