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The DSP will be responsible for resource management and controlincluding encryption=decryption, channelization, demodulation, and decoding=encoding.This functionality has been discussed in the previous chapters.As stated earlier, since most, if not all, of the services covered by the MSS are,in principle, provided by terrestrial switched digital networks (e.g. ISDN) wewill attempt to explain some the concepts applicable to ISDN that have notbeen previously dealt with in previous chapters.The network routers (gateways) allowSeamless intersatellite cross link; that is, direct data transfers from onesatellite to another,Seamless connectivity for users anywhere in the world through mobile=fixed earth stations and public-switched digital networksTraffic shaping, resource accounting, cache for traffic redirection andload sharing, and integrated network management to support amyriad of simultaneous connections per satelliteAny mobile station registered on the mobile satellite network is interconnectedto any available channel of the network interface gateway (NIG) throughproper channel assignments issued by the network access gateway (NAG).When the satellite illuminates a particular area or region, the mobilesatellite system routes intended messages (e.g., telephone calls, data, etc.)through the ground networks (e.g., ISDN), ground stations, or directly to theuser terminals. User terminals can be personal terminals for individualsubscribers or multiuser terminals for corporate (e.g., Internet providers,communication resellers, etc) and communal residential subscribers.The public terrestrial switched networks, called in this text Land-basedDigital Switched Network (LDSN), contain the integrated services digitalnetwork (ISDN) and mobile communications systems to provide end userswith efficient communication services between fixed and fixed terminals, fixedand mobile terminals, and mobile and mobile terminals. In the networkarrangement shown in Fig. 8.1, any mobile stations using the services ofPLSN can communicate both signalling and bearer traffic to the basetransceiver station (BTS) that provides the most favorable radiofrequency(RF) signal. This establishes an association between the mobile station’sgeographic location and the closest BTS. As the mobile station moves fromthe coverage area of one BTS to another, the first association is released and anew one is formed. This procedure is called handover. The base stationcontroller (BSC) and mobile switching center (MSC) manage radio resources,channel assignments, and handover services. A single BSC can controlmultiple BTSs. A single MSC can control multiple BSCs. Multiple MSCsCopyright © 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
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Copyright © 2002 by Marcel Dekker,
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epeaters overshooting into subseque
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6. Conventional BPSK modulation all
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4Satellite LinksA satellite link co
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FIGURE 4.2 Basic antenna parameters
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For unity efficiency, and substitut
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This expression neglects losses oth
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This expression is equally valid fo
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and Lin [5]:whereL ¼L o1 þ L oðr
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3. Calculate attenuation A r in dB
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4.2.1 Intersatellite LinksAs indica
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We know from (4.4b) that f c is dep
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FIGURE 4.9 Cross-link transmission
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Follow the uplink procedure for the
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Satellite:Frequencies:14.75 GHz up
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6. For link to be maintained betwee
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5.1 PRINCIPLES OF MULTIPLE ACCESSAs
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neously, their transmissions collid
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technique and would remain the most
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FIGURE 5.4 Typical TDMA frame struc
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FIGURE 5.6TDMA throughput for an IN
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and transmits through the satellite
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FIGURE 5.8FDMA total capacity respo
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tion; that is, log e ð1 þ xÞ x t
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REFERENCES1. Spilker, J.J. (1977).
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6.1 CHANNEL CODINGNoise within a tr
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where G is a generator matrix that
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The syndrome is a single word of le
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SolutionComparing (i) and (ii) with
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Cyclic CodesCyclic codes are a subs
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When errors occur in bursts, the nu
Page 398: FIGURE 6.3Rate 1/2 convolutional en
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Page 406: FIGURE 6.6 Trellis diagram of Fig.
Page 410: FIGURE 6.9 Trellis diagram of Fig.
Page 414: A generalized Viterbi algorithm is
Page 418: 3. Huffman, D.A. (1952). A method f
Page 422: 4. Draw a block diagram for a convo
Page 426: 1. The first essential requirement
Page 430: use. The ITU Radio Regulations gove
Page 434: Within the CCITT structure exist a
Page 438: 7.2 NATIONAL AND REGIONAL REGULATIO
Page 442: 8Mobile Satellite System Services8.
Page 446: Copyright © 2002 by Marcel Dekker,
Page 452: 2. Provide a convenient framework w
Page 456: FIGURE 8.3Types of user-to-network
Page 460: H1-channels are designed to carry v
Page 464: information. The transfer cell prov
Page 468: The OSI layers are divided into two
Page 472: plane is denoted by U, the control
Page 476: interfacing, maintenance, and conne
Page 480: adjoining base station to scan the
Page 484: FIGURE 8.9Geometry of a polygon.The
Page 488: FIGURE 8.11Splitting cells into sma
Page 492: causes signal fading. Of course, th
Page 496: 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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