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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Wireless Communications Principles and Practice T.S. Rappaport 2 nd Edition.

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Presentation on theme: "© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Wireless Communications Principles and Practice T.S. Rappaport 2 nd Edition."— Presentation transcript:

1 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Wireless Communications Principles and Practice T.S. Rappaport 2 nd Edition Chapter 2: Modern Wireless Communication Systems

2 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.1 Growth of cellular telephone subscribers throughout the world.

3 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.2 Worldwide subscriber base as a function of cellular technology in late 2001.

4 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. 1 st Generation cellular systems relied on FDMA / FDD and Analog FM. 2 nd Generation standards use digital modulation formats and TDMA / FDD and CDMA / FDD. Global System Mobile (GSM) supports 8 time slotted users for each 200 kHz each, radio channel. Interim Standard 136 (IS-136) supports three time slotted users each of 30 kHz each. Pacific Digital Cellular (PDC) is similar to IS-136. Interim Standard 95 Code Division Multiple Access (IS-95), also known as cdmaOne supports up to 64 users that are orthogonally coded and simultaneously transmitted on each 1.25 MHz channel.

5 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited.

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8 Figure 2.3 Various upgrade paths for 2G technologies.

9 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. EVOLUTION TO 2.5G MOBILE RADIO NETWORKS 2 G technologies use circuit-switched data modems that limit data users to a single circuit-switched voice channel. Data through put of an individual user is limited. Data rates of the order of 10kbps supported which is slow for rapid and internet browsing. Data-centric 2.5 standards were introduced for increased throughput data rates to support modern Internet applications. 2.5G technologies support a popular web browsing format language called Wireless Applications Protocol (WAP) that allows standard webpages to be viewed in a compressed format designed for small, portable hand held devices.

10 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. EVOLUTION FOR 2.5G TDMA STANDARDS HSCSD for 2.5G GSM High Speed Circuit Switched Data is a circuit switched technique that allows a single mobile subscriber to use consecutive time slots in the GSM standard. Instead of limiting each user to a particular time slot, HSCSD allows individual data users to use consecutive user time slots in the GSM standard to obtain high speed data access. Data rate increases to 14,400 bps as compared to 9,600 bps in GSM. Using 4 consecutive time slots, HSCSD provides transmission rate of upto 57.6 kbps to individual users.

11 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. EVOLUTION FOR 2.5G TDMA STANDARDS GPRS for 2.5G GSM and IS-136 General Packet Radio Service is a packet-based data network which is well- suited for non-real time internet usage, including retrieval of , faxes and web browsing. GPRS supports multi-user network sharing of individual radio channels and time slots. Can support many more users as compared to HSCSD but in a bursty manner !! When all eight time slots of a GSM radio channel are dedicated to a GPRS, an individual user is able to achieve as much as kbps data throughput.

12 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. EVOLUTION FOR 2.5G TDMA STANDARDS EDGE for 2.5G GSM and IS-136 Enhanced Data rates for GSM Evolution is an enhanced version of GSM standard and requires addition of new hardware and software to existing BS. EDGE introduces a new modulation format 8-PSK (Octal Phase Shift Keying) which is used in addition to GMSK. Provides practical data rate of about 384 kbps for a single dedicated user on a single GSM channel. By combining the capacity of different radio channels (Multiple Carrier Transmission), EDGE can provide up to several megabits per second throughput.

13 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. 3G WIRELESS NETWORKS 3 G W-CDMA (UMTS) Universal Mobile Telecommunications System (UMTS) or Wide-band CDMA (W-CDMA) assures backward compatibility with 2.5G TDMA standards. Designed for Always-ON packet-based wireless service so that computers, mobiles and laptops etc. may all share the same wireless network to be connected to the Internet anytime, anywhere. W-CDMA supports data rates upto Mbps per user to allow high quality data, multimedia and streaming video broadcasting services. Requires a minimum spectrum allocation of 5 MHz where a channel (5 MHz) will be able to support 100 to 350 simultaneous voice calls at once.

14 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. 3G WIRELESS NETWORKS 3 G cdma2000 Channel bandwidth of 1.25 MHz per radio channel The first CDMA interface cdma2000 1xRTT means that a single 1.25 MHz radio channel is used. cdma2000 1X supports an instantaneous data rate upto 307 kbps with typical throughput rate of 144kbps. cdma2000 1xEV : Evolutionary advancement for CDMA cdma2000 1xEV-DO: CDMA carriers with the option of Data Only radio channels cdma2000 1xEV-DV: carriers with Data and Voice.

15 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. 3G WIRELESS NETWORKS 3 G TD-SCDMA Time Division Synchronous Code Division Multiple Access TD-SCDMA combines TDMA and TDD techniques to provide a data-only overlay in existing GSM network. Up to 384 kbps of packet data is provided to data users in TD-SCDMA. Radio channels are 1.6 MHz in bandwidth A 5ms frame is used which is divided into 7 time slots which are flexibly assigned to a single high data rate user or several slower users.

16 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited.

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18 Figure 2.4 Example of the emerging applications and markets for broadband services. (Courtesy of Harris Corporation, ©1999, all rights reserved.)

19 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. WIRELESS LOCAL LOOP (WLL) Wireless local loop (WLL), is a term for the use of a wireless communications link as the "last mile " connection that resides between the Central Office (CO) and the individual homes and businesses in close proximity of the CO.last mile LOCAL MULTIPOINT DISTRIBUTION SERVICE (LMDS) LMDS is a broadband wireless access technology originally designed for digital television transmission (DTV). It was conceived as a fixed wireless, point-to- multipoint technology for utilization in the last mile. LMDS commonly operates on microwave frequencies across the 26 GHz and 29 GHz bands. In the United States, frequencies from 31.0 through 31.3 GHz are also considered LMDS frequencies.broadband wirelessdigital television transmissionpoint-to- multipointlast mile microwave LMDS has been allocated a spectrum of 1300 MHz which can support over 200 broadcast quality channels or 65,000 full duplex voice channels.

20 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.5 Allocation of broadband wireless spectrum throughout the work. (Courtesy of Ray W. Nettleton and reproduced by permission of Formus Communications.)

21 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited.

22 Figure 2.7 A wireless Competitive Local Exchange Carrier (CLEC) using Asynchronous Transfer Mode (ATM) distribution.

23 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Local Exchange Carrier (LEC) LEC owns a very wide bandwidth Asynchronous Transfer Mode (ATM) or Synchronous Optical NETwork (SONET) backbone switch, capable of connecting hundreds of megabits per second of traffic with the Internet, the PSTN or some private network. As long as LOS path exists, LMDS allows LECs to install wireless equipment on the premises of customers for rapid broadband connectivity without having to lease or install its own cables to the customers.

24 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.8 Measured received power levels over a 605 m 38 GHz fixed wireless link in clear sky, rain, and hail [from [Xu00], ©IEEE].

25 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.9 Measured received power during rain storm at 38 GHz [from [Xu00], ©IEEE].

26 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.10 Overview of the IEEE Wireless LAN standard.

27 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. IEEE IEEE is a set of standards for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands.wireless local area network Provides 11 Mcps DS-SS spreading and 2Mbps user data rates. IEEE a provides upto 54 Mbps throughput in 5GHz band. DS-SS IEEE b standard has been named Wi-Fi by WECA (Wireless Ethernet Compatibility Alliance). IEEE g is developing Complementary Code Keying Orthogonal Frequency Division Multiplexing (CCK-OFDM) standards in both the 2.4 GHz (IEEE b) and 5 GHz (IEEE a) FH-SS : Frequency Hopping - Spread Spectrum DSSS : Direct-Sequence Spread Spectrum

28 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.11 Photographs of popular b WLAN equipment. Access points and a client card are shown on left, and PCMCIA Client card is shown on right. (Courtesy of Cisco Systems, Inc.)

29 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.12 Channelization scheme for IEEE b throughout the world.

30 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.13 A predicted coverage plot for three access points in a modern large lecture hall. (Courtesy of Wireless Valley Communications, Inc., ©2000, all rights reserved.)

31 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.14 Schematic of an experiment to determine how received interference impacts end user performance on a WLAN network [Hen01] demonstrated that a CAD prediction and measurement environment can be used to accurately and rapidly predict true end user throughput in a multi-node network using blind prediction. Such capabilities will be vital as user densities increase in WLAN networks within buildings or campuses.

32 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.15 A typical neighborhood where high speed license free WLAN service from the street might be contemplated [Dur98b].

33 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Figure 2.16 Measured values of path loss using a street-mounted lamp-post transmitter at 5.8 GHz, for various types of customer premise antenna [from [Dur98], ©IEEE].

34 © 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited.

35 Figure 2.17 Example of a Personal Area Network (PAN) as provided by the Bluetooth standard.


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