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can be used at separate user-to-network interfaces to provide access to a varietyof communication modes within the ISDN. For example, two B-channels maybe attached to each other via network-provided circuit-switched or packetswitchedconnections, or by permanent or temporary connections based oncircuit switching or packet switching.The C-channel is primarily assigned to telemetry and packet-switcheddata. The channel may have a variable data rate, and by virtue of its layeredprotocol may be mixed with signalling information for an analog channel.More is said about ‘‘layered protocols’’ ahead.The D-channel primary function is to carry signalling information forthe control of circuit-switched connections involving one or more B-channelsbetween the end user and the network. Two types of D-channels have beendefined: layered protocols and X.25. Both operate at synchronous data rates ofeither 16 kbit=sec or 64 kbit=sec in full duplex.The E-channel is a 64 kbit=sec channel intended to transmit signallinginformation for circuit-switched ISDN. It may be used for multiplexing andproviding multiple-access interfaces.The H-channel is designed for a variety of user information functionswith channel capacity greater than the B-channel’s. Currently, there are fourtypes of H-channels: H0, H1, H2 and H4 with successively higher rates (seeTable 8.1.) Channels H1 and H2 exist in two versions: denoted as H11 andH12, and H21 and H22.The H0-channel operates at a full duplex synchronous data rate, sixtimes the B-channel rate, which is a submultiple of CCITT multiplexstructures (for example, 1.544 Mbit=sec and 2.048 Mbit=sec). TheH0-channel is suitable for standard broadcast digital audio programs.TABLE 8.1H-Channel Transmission (Data) RatesComponentchannelData rate kbit=secMultiple of B-channel rateH0 384 6H1 H11 1536 24H12 1920 30H2 H21 32,768 512H22 44,160 690H4 135,168 2112Copyright © 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
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FIGURE 6.3Rate 1/2 convolutional en
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us to a particular node in the tree
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 450: may reside within a single LDSN. Th
Page 454: destination through the intermediat
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
Page 500: access to an Internet point of pres
Page 504: 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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