Ammar Abu-Hudrouss Islamic University Gaza

Transcription

1 Wireless Communications n Ammar Abu-Hudrouss Islamic University Gaza ١

2 Course Syllabus References 1. A. Molisch,, Wiely IEEE, 2nd Edition, Rappaport, p : Principles and Practice, Prentice Hall 2 nd Ed 3. D. N. C. Tse and P. Viswanath, Fundamentals of Wireless Communication, Cambridge, U.K., Andrea Goldsmith,, Cambridge University Press Slide 2

3 Course Syllabus Course Content: Cellular Concept (ch. 3-Ref 2). Wireless Channel Characteristics (ch 4-Ref 2). Statistical Description of the wireless Channel. Diversity techniques for the receiver and the transmitter (ch 13 Ref 1). Technical Challenges of Multiple access, Random access, power control Spread spectrum : DSSS and FSSSS MIMO and Orthogonal Frequency Division Multiplexing (OFDM) Advanced topics according to the available time. Slide 3

4 Course Syllabus Grading Policy The final course grade will be distributed as follows: Quizzes and class activity 20 % Project 10 % Midterm exam 25 % Final exam 45 % Plagiarism will not be tolerated at any case. Copying homework from your colleagues or project from any source will lead to severe consequences. Slide 4

5 Introduction Communication is an essential need of human being, e.g., conversation, letter. Wireless used to be the only (limited and unreliable) way to communicate in ancient times. Modern wireless communications are based on the electromagnetic field theory (Maxwell s equations, Marconi s invention) Slide 5

6 Wireless is often prior to its wired counterpart and has become an important supplement: Marconi s Wireless Telegraph Wired Telegraph & Telephone Cordless, Cellular Telephone, and Wireless Local Loop Broadcast TV Cable TV Satellite TV Aloha Network Ethernet Wireless LAN Slide 6

7 Characteristics of Convenience and reduced cost Service can be deployed faster than fixed service No cost of cable plant Service is mobile, deployed almost anywhere Unreliable channel (attenuation, fading, shadowing, interference) Complicated design and management Device limitations (power supply, LCD) Limited bandwidth and expensive service Slide 7

8 Basic Concepts Simplex, half-duplex, and full duplex Base Station Mobile Station Subscriber Transceiver Mobile Switching centre Control Channel Roamer Handoff Page Slide 8

9 Electromagnetic Spectrum Slide 9

10 Evolution of Wireless Communciations Improved mobile telephone system (IMTS) developed in 1960 Full duplex services and direct-dialing 23 FM channels with BW reduced to KHz Cellular concept Exploits the attenuation of radio signal with distance to achieve frequency reuse. originally proposed by D. H. Ring in 1947 Bell Labs began work on cellular telephone system in the late 1960s. Slide 10

11 Evolution of (1G) Handoff was not solved until the development of micro- processor, efficient remote-controlled RF synthesizer, and switching center. 1G Cellular System Designed in 1970s, deployed in early 1980s Analog, 42 control channels, 790 voice channels Handoff performed at BS based on received power AMPS in US; TACS in part of Europe; NTT in Japan; C450 in West German, and NMT in some countries. Analog System is used Slide 11

12 Cellular System Mobile identification number (MIN) electronic serial number (ESN) Slide 12

13 Evolution of (2G) 2G Systems Digital cellular telephony Modest data support, GSM: a common TDMA technology for Europe; claim about 3/4 of subscribers worldwide. IS-54 and IS-136: TDMA technology in US; compatible with AMPS; IS-95: CDMA; standardized in 1993; South Korea and Hong Kong deployed it in 1995; US in Slide 13

14 Evolution of (3G) IMT-2000 comprises several 3G standards: EDGE, data rate up to 473Kbps, backward compatible with GSM/IS-136 cdma2000 (Qualcomm), data rate up to 2Mbps, backward compatible with IS-95 WCDMA (Europe), introduces a new 5MHz channel structure; data rate up to 2Mbps; TD-SCDMA (China), CDMA in TDD fashion Slide 14

15 2G to 3G evolution Slide 15

16 4G and LTE (long term evolution) OFDM/MIMO Much higher data rates ( Mbps) Greater spectral efficiency i (bits/s/hz) /H Flexible use of up to 100 MHz of spectrum Low packet latency (<5ms). Increased system capacity Reduced cost-per-bit Support for multimedia Slide 16

17 Pager System Slide 17

18 Pager System Broad coverage for short messaging Message broadcast from all base stations Simple terminals Optimized for 1-way transmission in many places, it is overtaken by cellular l Slide 18

19 Cordless phone DC2 and DECT standards Slide 19

20 Bluetooth Cable replacement RF technology (low cost) Short range (10m, extendable to 100m) 2.4 GHz band (crowded) 1 Data (700 Kbps) and 3 voice channels, up to 3 Mbps Widely supported by telecommunications, PC, and consumer electronics companies Few applications beyond cable replacement Slide 20

21 IEEE / ZigBee Radios Low-Rate WPAN Data rates of 20, 40, 250 Kbps Support for large mesh networking or star clusters Support for low latency devices CSMA-CA channel access Very low power consumption Frequency of operation in ISM bands Focus is primarily on low power sensor networks Slide 21

22 Satellite Systems Cover very large areas Different orbit heights GEOs (39000 Km) versus LEOs (2000 Km) Optimized for one-way transmission Global Positioning System (GPS) use growing Satellite signals used to pinpoint i location Popular in cell phones, PDAs, and navigation devices Slide 22

23 Wireless Local Area Networks (WLANs) Internet Access Point WLANs connect local computers (100m range) Breaks data into packets Channel access is shared (random access) Backbone Internet provides best-effort service Poor performance in some apps (e.g. video) Slide 23

24 Wifi Networks (Supporting Multimedia) n++ Streaming video Gbps data rates High reliability Coverage in every room Slide 24 Wireless HDTV and Gaming

25 Wimax (802.16) Wide area wireless network standard System architecture similar to cellular Hopes to compete with cellular OFDM/MIMO is core link technology Operates in 2.5 and 3.5 MHz bands Different for different countries, 5.8 also used. Bandwidth is MHz Fixed (802.16d) vs. Mobile (802.16e) Wimax Fixed: 75 Mbps max, up to 50 mile cell radius Mobile: 15 Mbps max, up to 1-2 mile cell radius Slide 25