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FIGURE 3.19A generalized model of a digital communication system.symbols from a finite source states x i , which are traversed via a discretememoryless channel (DMC) to produce data y i .The output data y i , which contain N symbols, can be viewed as a timesequence of source states. The term memoryless implies that the source outputis independent of all preceding and succeeding source outputs. For convenience,we write the input and output states asX ¼ðx 1 ; x 2 ; x 3 ; ...; x M ÞY ¼ðy 1 ; y 2 ; y 3 ; ...; y N Þð3:58ÞThe theory of effective encoding of signals from various sources is a branch ofmodern information theory. The results of the theory descend from theShannon theorem, which states that the minimum average number of symbolsnecessary for data transmission from some sources equals its entropy, H. Thus,entropy implies the average information associated with the sources; theaverage is over all source states. The information I associated with sourcestates x i is1Iðx i Þ¼log a ð3:59Þpðx i Þwhere a, the base of the logarithm, determines the unit in which theinformation is measured. Also, pðx i Þ is the probability that the source stateis transmitted. From elementary mathematics, the sum of the source probabilitiesis unity:P Mi¼1Note thatpðx i Þ¼1log a k ¼ log 10 klog 10 að3:60aÞð3:60bÞEquation (3.59) satisfies these three conditions:1. Iðx i Þ0 within the bound 0 pðx i Þ1.2. As pðx i Þ approaches unity, Iðx i Þ approaches zero.Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
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SatelliteCommunicationEngineeringMi
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This book is dedicated to my famili
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Because of the immense importance o
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means of a combination of applicati
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about my promise to my students, an
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2.3 Coverage Area and Satellite Net
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1Basic Principles of SatelliteCommu
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and voice (telephone) communication
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FIGURE 1.2Communication between two
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interpreting or uncovering the deci
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cryptographic keys K ti (where i ¼
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FIGURE 1.6Block ciphering technique
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FIGURE 1.7Part of block ciphering w
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Based on the ordering sequence of (
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TABLE 1.1 (continued )S612 1 10 15
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For an uncoded message x and the fe
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2. Your task is to develop a commun
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FIGURE 2.1Geometry of a satellite.
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Future trends in satellite antennas
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In the United States, the three sat
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TABLE 2.3Typical Links Frequency Ba
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FIGURE 2.4Satellite period and orbi
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FIGURE 2.6An illustration of covera
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FIGURE 2.7constellation.A sketch of
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width of 1:73 with reduced coverag
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y ¼ elevation angle of satellite f
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We can conclude that the antenna mu
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FIGURE 2.9Design flowchart of a sat
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Risk control and monitoring measure
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TABLE 2.4Antenna Selection Criteria
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Then the system availability can be
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In fact, MTBF is the reciprocal of
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2.7 ANTENNASBased on function, sate
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Two kinds of horns in common use ar
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FIGURE 2.13Geometry of a parabolic
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FIGURE 2.14 Axisymmetric reflector
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A transceiver antenna is a single a
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The gain, in the axial mode, of a h
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angles, spacecraft may shadow the s
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3. The probability of both parallel
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the baseband signal (more details a
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matrix in the communications subsys
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FIGURE 2.24Typical transfer charact
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4. Iridium LCC (1997). Iridium Syst
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3Earth StationsIn Chap. 2 we discus
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The most popular forms of modulatio
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Small earth stations are antennas w
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FIGURE 3.2BPSK space diagram.Instea
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OQPSKOffset QPSK (OQPSK) is a modif
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FIGURE 3.7An 8-PSK space diagram.an
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aud. The word ‘‘baud’’ hono
Page 206: Noise power density N 0bandwidth:N
Page 210: We observe in (3.11) that E b =N 0
Page 214: to (3.23) shows that a margin of 11
Page 218: FIGURE 3.12 Principle of scrambling
Page 222: Equalization FilterAn equalization
Page 226: that is, N zeros at the top and bot
Page 230: Example 3.2: Consider a transmissio
Page 234: which can be written as89>=R xy ðt
Page 238: ecause a voice signal is usually hi
Page 242: systems is discussed in Sec. 4.2. O
Page 246: where T e is the equivalent tempera
Page 250: operating principle of all directio
Page 254: performance of the satellite commun
Page 260: FIGURE 3.20Entropy of a binary sour
Page 264: whereHðYÞ¼output entropy, the av
Page 268: To have a feel for this expression,
Page 272: 2. The system’s overall condition
Page 276: transmitted down the fiber as digit
Page 280: 10. Kantor, L. Y. (ed). (1987). Han
Page 284: 142. Simulate the probability of bi
Page 288: FIGURE 4.1A simplex link.baseband c
Page 292: Chapter 2, Sec. 2.7, discusses that
Page 296: From (4.6), the received power P r
Page 300: FIGURE 4.3A model of the combined-l
Page 304: 4.1.2 Rain AttenuationRain attenuat
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FIGURE 4.5rates.Average rainstorm p
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FIGURE 4.6Adjacent satellite interf
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FIGURE 4.8Satellite separation dist
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inability of satellite A to accurat
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FIGURE 4.10 Cross-link E b =N 0 vs.
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Then using (4.41), the overall C=N
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(iv)(v)(vi)(vii)Calculate the recei
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5Communication Networks andSystemsC
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discriminate among carriers by temp
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FIGURE 5.2 Principle of FDMA system
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FIGURE 5.3 Operational concept of T
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FIGURE 5.5TDMA: bit rate r b for 1
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Copyright © 2002 by Marcel Dekker,
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5.2 CAPACITY COMPARISON OFMULTIPLE-
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Rearranging (5.11) in terms of ener
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The transmission bit rate isR r ¼
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6Error Detection and CorrectionCodi
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the channel and reconstruct the sou
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message sequence X . Thus, a system
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If we consider a message X ¼ð1010
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can be seen in Table 6.1 that the m
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FIGURE 6.1A (7, 4) cyclic code gene
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FIGURE 6.2Convolutional codes encod
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Alternative methods of describing a
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FIGURE 6.5 Code tree diagram of Fig
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FIGURE 6.8 Code tree diagram of rat
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consistent with the constraint leng
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trellis depth is approximated to 5L
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FIGURE P.1A convolutional coder.the
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7Regulatory Agencies andProceduresT
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of the radiofrequency spectrum, and
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The CCIR works through the medium o
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7.1.3 IFRBThe International Frequen
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The national or regional spectrum m
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3. The need to expand or enhance th
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The DSP will be responsible for res
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2. Provide a convenient framework w
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FIGURE 8.3Types of user-to-network
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H1-channels are designed to carry v
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information. The transfer cell prov
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The OSI layers are divided into two
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plane is denoted by U, the control
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interfacing, maintenance, and conne
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adjoining base station to scan the
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FIGURE 8.9Geometry of a polygon.The
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FIGURE 8.11Splitting cells into sma
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causes signal fading. Of course, th
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FIGURE 8.14TCP=IP suite and its rel
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access to an Internet point of pres
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message security via satellite is d
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REFERENCES1. Wu, W.W. (1989). Eleme
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Appendix ANotationsThe symbols have
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N sPP rP sP TRRðtÞR cR eR rR vSS
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g Central anglez Channel gainZ Ante
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AttenuationBandwidthBearer serviceB
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Frequency divisionmultiple accessFr
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MultiplexingNetworkOmnidirectionala
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UplinkUser-to-networkinterfaceThe e
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