1 ECE 5325/6325: Wireless Communication SystemsLecture Notes, Fall 2011 Prof. Neal PatwariUniversity of UtahDepartment of Electrical and Computer Engineeringc 2011 ECE 5325/6325 Fall 20112 Contents1 Cellular Systems Generation Zero .. Cellular .. Key Terms .. 72 Frequency Transmit Power Limits .. Cellular Geometry .. Channel Assignment within Group .. Large-scale Path Loss .. Co-Channel Interference .. Downtilt .. Handoff .. Review from Lecture 2 .. Adjacent Channel Interference .. 153 Blocked calls cleared .. Blocked calls delayed .. Discussion .. 184 Increasing Capacity and Sectoring.
2 Determiningi0.. Example .. Microcells .. Repeaters .. Discussion .. 215 Free Space Received Power Reference .. Antennas .. Power Flux Density .. 236 Large Scale Path Loss Log Distance Path Loss .. Multiple Breakpoint Model .. 267 Reflection and Transmission268 Two-Ray (Ground Reflection) Direct Path .. Reflected Path .. Total Two-Ray E-Field .. 29 ECE 5325/6325 Fall 201139 Indoor and Site-specific Large Scale Path Loss Attenuation Factor Models .. Ray-tracing models .. 3110 Link Link Budget Procedure .. Thermal noise .. Examples .. 3411 Diffraction3512 Rough Surface Scattering3613 Multipath Multipath.
3 Temporal .. Channel Impulse Response .. Received Power .. Time Dispersion Parameters .. Review from Lecture 9 .. 4114 Fade Rayleigh Fading .. Ricean fading .. 4315 Doppler One Component .. Many Components .. System Design Implications .. 4616 Digital Communications: Orthogonal Waveforms .. Linear Combinations .. UsingMDifferent Linear Combinations .. Reception .. How to Choose a modulation .. Intersymbol Interference and Bandwidth .. 5117 PAM .. M-ary QAM and PSK .. FSK .. MSK .. Receiver Complexity Options .. 5418 Fidelity54 ECE 5325/6325 Fall 2011419 Link Budgets with Digital Shannon-Hartley Channel Capacity.
4 Examples .. Q-Function and Inverse .. 5820 Implementation Power Amplifiers and Constant Envelope .. Offset QPSK .. Other Modulations .. Synchronization .. Energy Detection of FSK .. Differential PSK .. 6421 Multi-carrier OFDM .. Orthogonal Waveforms .. Fourier Transform Implementation .. Cyclic Prefix .. Problems with OFDM .. Examples .. 6822 Forward Error Correction Block vs. Convolutional Coding .. Block Code Implementation .. Performance and Costs .. 7123 Error Detection via Generation of the CRC .. Performance and Costs .. 7324 Spread FH-SS .. DS-SS .. PN code generation.
5 7625 Medium Access Control7926 Packet Aloha .. Slotted Aloha .. 8027 Carrier Sensing .. Hidden Terminal Problem .. DCF .. In-Class DCF Demo .. RTS/CTS .. 84 ECE 5325/6325 Fall 2011528 Methods for Channel Diversity .. Space Diversity .. Polarization Diversity .. Frequency Diversity .. Multipath diversity .. Time Diversity .. Diversity Combining .. Selection Combining .. Scanning Combining .. Equal Gain Combining .. Maximal Ratio Combining .. 8929 Shannon-Hartley Bandwidth Efficiency9030 Revisit Maximal Ratio Combining .. Alamouti code .. MIMO Channel Representation.
6 Capacity of MIMO Systems .. 95 ECE 5325/6325 Fall 20116 Lecture 1 Today: (1) Syllabus, (2) Cellular Systems Intro1 Cellular Systems Generation ZeroThe study of the history of cellular Systems can help us understand the need for the system designconcepts we have of the major developments in WWII was the miniaturization of FM radio components toa backpack or handheld device (the walkie-talkie), a half-duplex (either transmit or receive, notboth) push-to-talk Communication device. After returningfrom war, veterans had the expectationthat Wireless communications should be available in their civilian jobs . But the phone system,the Public Switched Telephone Network (PSTN) was: wired, and manually switched at telephoneexchanges.
7 In 1952, the Mobile Telephone System (MTS) was designed to serve 25 cities in the US (including one in Salt Lake City ). In each city, an additional telephone exchange office wascreated for purpose of connection with the mobile telephones . The MTS and later the improvedmobile telephone system (IMTS), introduced in 1964, were not particularly spectrally efficient. They were allocated a total bandwidth of about 2 MHz. Frequency modulation (FM) wasused. For multiple user access, the system operated frequency division multiple access(FDMA), in which each channel was allocated a non-overlapping frequency band within the2 MHz.
8 The PTSN is full duplex (transmit and receive simultaneously) in IMTS, so it required twochannels for each call, one uplink (to the base station) and one downlink (to the mobilereceiver). Note MTS had been half duplex, , only one party could talk at once. The FCC required them to operate over an entire city (25 mile radius). Since the coveragewas city wide, and coverage did not exist outside of the cities, there was no need for handoff. Initially channels were 120 kHz , due to poor out-of-bandfiltering. The channel bandwidthwas cut to 60 kHz in 1950 and again to 30 kHz in 1965. Thus there were 2 MHz / 2 / 120kHz or 8 full duplex channels at the start, and up to 32 in 1965,for the entire was manual, and the control channel was open for anyone to hear.
9 In fact, users wererequired to be listening to the control channel. When the switching operator wanted to connect toany mobile user, they would announce the call on the control channel. If the user responded, theywould tell the user which voice channel to turn to. Any other curious user could listen as well. Amobile user could also use the control channel to request a call to be connected. The system wascongested, so there was always demand was very high, even at the high cost of about $400 per month (in 2009 dollars).There were a few hundred subscribers in a city  but up to 20,000 on the waiting list . Theonly way to increase the capacity was to allocate more bandwidth, but satisfying the need wouldhave required more bandwidth than was 5325/6325 Fall 20117 The downsides to MTS took a significant amount of technological development to address, andthe business case was not clear (AT&T developed the technologies over 35 years, but then largelyignored it during the 1980s when it was deployed ).
10 CellularThe cellular concept is to partition a geographical area into cells , each covering a small fractionof a city. Each cell is allocated a channel group , , a subset of the total list of channels. Asecond cell, distant from a first cell using a particular channel group, can reuse the same channelgroup. This is called frequency reuse . This is depicted inFigure in Rappaport. This assumesthat at a long distance, the signals transmitted in the first cell are too low by the time they reachthe second cell to significantly interfere with the use of those channels in the second are dramatic technical implications of the cellular concept.