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Follow the uplink procedure for the downlink case and consider additiveinterfering signals on the downlink with respective powers, say I d1 ; I d2 ; ...; I dkwithin the bandwidth of the desired carrier. As such, the corresponding carrierto-noiseplus interference ratio can be written as C¼C þ Pk C dNDINd i¼1 I di¼C N dþ C ð4:40ÞIdThus, the combined carrier-to-noise ratio for a single-hop transmission isCN ¼ 1ðC=NÞ 1UI þðC=NÞ1ð4:41ÞDIThis expression is the most widely used equation in satellite system engineering.Care must be taken when applying (4.41). For example, when rain occurson the downlink only, the carrier-to-noise and interference are attenuatedequally. As such, the downlink carrier-to-interference ratio remains at theclear-sky value and Eq. (4.40) is used: meaning that the rain attenuation factoris not included. However, if rain occurs in both uplink and downlink, the effectof rain-induced attenuation must be included in the link calculation, which isto further reduce the carrier-to-noise plus interference ratio of the link beingconsidered.The overall system quality E b =N 0 , the bit energy-to-noise plus interferencedensity ratio, can be computed from (4.41) and (3.11).Example 4.4: A satellite system uplink was designed so that the transpondercarrier-to-noise plus interference ratio is 22.5 dB. The link is cascaded with thedownlink for which the receiver carrier-to-noise plus interference ratio is16.25 dB. Estimate the overall carrier-to-noise ratio of the cascaded link.SolutionConvert the carrier-to-noise plus interference ratios into power ratio form: C¼ 10 2:25 ¼ 177:828NandUI C¼ 10 1:625 ¼ 42:1697NDICopyright © 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
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Noise power density N 0bandwidth:N
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We observe in (3.11) that E b =N 0
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to (3.23) shows that a margin of 11
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FIGURE 3.12 Principle of scrambling
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Equalization FilterAn equalization
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that is, N zeros at the top and bot
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Example 3.2: Consider a transmissio
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which can be written as89>=R xy ðt
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ecause a voice signal is usually hi
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systems is discussed in Sec. 4.2. O
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where T e is the equivalent tempera
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operating principle of all directio
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performance of the satellite commun
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3. For two independent sources, wit
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FIGURE 3.21 A representation of mut
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In practice, Eqs. (3.78) and (3.76)
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This condition is always satisfied
Page 274: Copyright © 2002 by Marcel Dekker,
Page 278: epeaters overshooting into subseque
Page 282: 6. Conventional BPSK modulation all
Page 286: 4Satellite LinksA satellite link co
Page 290: FIGURE 4.2 Basic antenna parameters
Page 294: For unity efficiency, and substitut
Page 298: This expression neglects losses oth
Page 302: This expression is equally valid fo
Page 306: and Lin [5]:whereL ¼L o1 þ L oðr
Page 310: 3. Calculate attenuation A r in dB
Page 314: 4.2.1 Intersatellite LinksAs indica
Page 318: We know from (4.4b) that f c is dep
Page 322: FIGURE 4.9 Cross-link transmission
Page 328: Then using (4.41), the overall C=N
Page 332: (iv)(v)(vi)(vii)Calculate the recei
Page 336: 5Communication Networks andSystemsC
Page 340: discriminate among carriers by temp
Page 344: FIGURE 5.2 Principle of FDMA system
Page 348: FIGURE 5.3 Operational concept of T
Page 352: FIGURE 5.5TDMA: bit rate r b for 1
Page 356: Copyright © 2002 by Marcel Dekker,
Page 360: 5.2 CAPACITY COMPARISON OFMULTIPLE-
Page 364: Rearranging (5.11) in terms of ener
Page 368: The transmission bit rate isR r ¼
Page 372: 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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