WIRELESS AND MOBILE COMMUNICATION

1. WIRELESS AND MOBILE COMMUNICATION A.M.BALAMURUGAN

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

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

4. Long Electrical Oscillations Ultraviolet Visible lights Gamma rays -8 -7 -6 -4 -2 -1 0 3 6 10 11 Radio- waves X-rays Infrared Cosmic rays Micro- waves (wavelength in 10x micrometer) Electromagnetic spectrum - Robert J. Hoss et al, “Fiber Optics”, ISBN 0133212416, Prentice-Hall, 1993, pp24.

5. twisted pair coax cable optical transmission 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100 m 3 THz 1 m 300 THz visible light VLF LF MF HF VHF UHF SHF EHF infrared UV Communication Frequencies Frequency and wave length:  = c/f wave length , speed of light c  3x108m/s, frequency f

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

7. 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.

8. Multiple access schemes • How to allow many wireless terminals to share a • finite amount of radio spectrum simultaneously? • Fixed Access • Random Access - T.S. Rappaport, “Wireless communications, principles & practice”, ISBN 0133755363, Prentice-Hall, 1996, pp395-438.

9. 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., CT2, DECT). • Code Division Multiple Access (CDMA): • Part/entire spectrum/time alloted to user differentiated by appropriate coding • ( e.g. 3rd generation of wireless networks). - T.S. Rappaport, “Wireless communications, principles & practice”, ISBN 0133755363, Prentice-Hall, 1996, pp395-438.

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

11. CDMA Courtesy of Suresh Goyal & Rich Howard

12. Courtesy of Suresh Goyal & Rich Howard

13. Courtesy of Suresh Goyal & Rich Howard

14. Courtesy of Suresh Goyal & Rich Howard

15. 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.

16. Forward channel (downlink) Reverse channel (uplink) Mobile Base-station Duplexing technologies • Duplexing enables mobile users to send and receive (talk / listen) “simultaneously”: • Frequency division duplex (FDD): use two distinct band of frequencies for every user  expensive duplexers • 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, pp395-396.

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

18. First Mobile Radio Telephone1924 Courtesy of Rich Howard

19. Region TAXI City laptops, PDAs Campus In-Building WIRELESS DATA VISION Seamless Multimedia Networks with Mobility and Freedom from Tethers [R. Katz, "Does Wireless Data Have a Future?", Plenary Talk, INFOCOM '96] 8C32810.35-Cimini-7/98

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

21. Cellular networks: Development • First generation: • Based on analog technology, uses a single base station to communicate with a single portable terminal. (e.g., Advance Mobile Phone Services - AMPS) • Second generation: • Based on digital modulation and advanced call processing capabilities . (e.g., Global System for Mobile - GSM and Cordless Telephone - CT2). • Third generation: • To 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, pp445-449.

22. First Generation • Advanced Mobile Phone Service (AMPS) • US trials 1978; deployed in Japan (’79) & US (’83) • 800 MHz band — two 20 MHz bands • TIA-553 • Still widely used in US and many parts of the world • Nordic Mobile Telephony (NMT) • Sweden, Norway, Demark & Finland • Launched 1981; now largely retired • 450 MHz; later at 900 MHz (NMT900) • Total Access Communications System (TACS) • British design; similar to AMPS; deployed 1985 • Some TACS-900 systems still in use in Europe

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

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

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

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

27. One timeslot = 0.577 ms One TDMA frame = 8 timeslots 200 KHz 200 KHz 200 KHz 200 KHz Time Frequency 2G — TDMATime Division Multiple Access

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

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

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

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

32. cdmaOne — IS-95 • TIA standard IS-95 (ANSI-95) in 1993 • IS-95 deployed in the 800 MHz cellular band • J-STD-08 variant deployed in 1900 MHz US “PCS” band • Evolution fixes bugs and adds data • IS-95A provides data rates up to 14.4 kbps • IS-95B provides rates up to 64 kbps (2.5G) • Both A and B are compatible with J-STD-08 • All variants designed for TIA IS-41 core networks (ANSI 41)

33. 2G & 3G — CDMACode Division Multiple Access • Spread spectrum modulation • Originally developed for the military • Resists jamming and many kinds of interference • Coded modulation hidden from those w/o the code • All users share same (large) block of spectrum • One for one frequency reuse • Soft handoffs possible • Almost all accepted 3G radio standards are based on CDMA • CDMA2000, W-CDMA and TD-SCDMA

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

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

36. A general WLL setup

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

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

39. LEO MEO GEO Satellite cost (unit) Satellite life (year) Hand-held terminal Propagation delay Propagation loss Network complexity Hand-off Development period Visibility of satellite Minimum 3-7 Possible Short Low Complex Very Long Short Medium 10-15 Possible Medium Medium Medium Medium Short Medium Maximum 10-15 Very Difficult Large High Simple No Long Always Satellite networks: Comparison -A. Jamalipour, “Low Earth Orbital Satellites for Personal Communication Networks”, ISBN 0890069557, Artech-House, 1998, pp17.

40. GEO MEO LEO 10,000~ 20,000 35,786 (km) GEO=Geostationary EO MEO=Medium EO LEO=Low EO EO=Earth Orbit >1,500 Satellite networks: Orbit altitude -A. Jamalipour, “Low Earth Orbital Satellites for Personal Communication Networks”, ISBN 0890069557, Artech-House, 1998, pp15.

41. 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/er3_98/art1/art1.html

42. STANDARDS AND FUTURE SYSTEMS • Bluetooth • Wireless LANs • High-Speed Digital Cellular (3G) • 4G Cellular • Wireless "Cable" – Multichannel Multipoint Distribution Service (2.2 GHz) – Local Multipoint Distribution Service (28 GHz) • Satellite Networks - Iridium, Globalstar, Others • HomeRF 8C32810.61-Cimini-7/98

43. 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 !

44. Ultimate Headset

45. Cordless Computer

46. Automatic Synchronization In the Office At Home

47. Bluetooth Specifications

48. 802.11 Wireless LANs • 802.11b: 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 • 802.11a extends rates to 10-70 Mbps • Extensions trying to add QoS 8C32810.63b-Cimini-7/98

49. Wireless LANIEEE 802.11a/b/g/h/j/n • b : 1999 ~2.4 GHz ISM • a : 2002 – 2003 ~5.0 GHz ISM • g : 2002 – 2003 ~2.4 GHz ISM • h : 2003 – 2004 ~5.0 GHz ISM • j : 2004 ~5.0 GHz ISM • n : 2006

50. Modulation & Filter type • b  DBPSK / DQPSK ( 11Mbps ) • 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 )