View File - University of Engineering and Technology, Taxila

More documents

Recommendations

Info

shown in Fig. 8.1. Some of the attributes of mobile communications systemsinclude [10]The extensive frequency reuse with a large number of widely dispersedlow-power transmitters located at the base stationsComputer-controlled capabilities to set up automatic handovers frombase station to base station when the signal strength or transmissiondistance can be improved to a more acceptable valueThe major differences between mobile–satellite communications and land–mobile communications include path loss, noise environment, and fadingcharacteristics. Path loss and noise are discussed in Chaps. 3 and 4, and fadingis covered ahead. The functional components comprising mobile communicationsare described in Sec. 8.2. Our next task is to describe the basic call setupfor a mobile (cellular) terminal.Call SetupWhen a call is placed, the handset first senses the presence or absence ofcellular frequencies and attempts to place a call through the local cellularnetworks if they are available. If cellular service is blocked or not available, thenetwork operator routes the call through the satellite for an acknowledgmentof the call status. User circuits established through a particular base transceiverstation enter the ground networks (e.g., ISDN) through the satellite gatewaylocated within the region being served. Call setup is thus established throughan order wire to a mobile switch center (MSC). Often a separate order wire isassigned to each satellite antenna beam. To make a circuit request, the userterminal (handset) transmits requests via order wires to satellite. The user (1) isassigned a beam that provides the strongest signal to the base transceiverstation and (2) is then instructed to use a suitable power level and particularaccess technique appropriate to the beam. In some cases with very long calls,circuit transfer to another satellite is performed without the callers’ participation.When the user is moving outside the beam coverage, the call is handedover to the next beam—a process called handover. For call setup via orderwire, each base station constantly monitors the strength of the modulatedsignals it is receiving from each user. When the quality of this signal fallsbelow certain preassigned norms (values) because the direct path signal mayhave been attenuated or the cellular user is moving outside the beam coverage,the base station sends a request to the centralized cellular switch (MSC) askingit to attempt a handover. The base station is usually located in the barocenter(center of the cell) of the service area. The switch then automatically asks eachCopyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
Page 2:
SatelliteCommunicationEngineeringMi
Page 6:
This book is dedicated to my famili
Page 10:
Because of the immense importance o
Page 14:
means of a combination of applicati
Page 18:
about my promise to my students, an
Page 22:
2.3 Coverage Area and Satellite Net
Page 26:
1Basic Principles of SatelliteCommu
Page 30:
and voice (telephone) communication
Page 34:
FIGURE 1.2Communication between two
Page 38:
interpreting or uncovering the deci
Page 42:
cryptographic keys K ti (where i ¼
Page 46:
FIGURE 1.6Block ciphering technique
Page 50:
FIGURE 1.7Part of block ciphering w
Page 54:
Based on the ordering sequence of (
Page 58:
TABLE 1.1 (continued )S612 1 10 15
Page 62:
For an uncoded message x and the fe
Page 66:
2. Your task is to develop a commun
Page 70:
FIGURE 2.1Geometry of a satellite.
Page 74:
Future trends in satellite antennas
Page 78:
In the United States, the three sat
Page 82:
TABLE 2.3Typical Links Frequency Ba
Page 86:
FIGURE 2.4Satellite period and orbi
Page 90:
FIGURE 2.6An illustration of covera
Page 94:
FIGURE 2.7constellation.A sketch of
Page 98:
width of 1:73 with reduced coverag
Page 102:
y ¼ elevation angle of satellite f
Page 106:
We can conclude that the antenna mu
Page 110:
FIGURE 2.9Design flowchart of a sat
Page 114:
Risk control and monitoring measure
Page 118:
TABLE 2.4Antenna Selection Criteria
Page 122:
Then the system availability can be
Page 126:
In fact, MTBF is the reciprocal of
Page 130:
2.7 ANTENNASBased on function, sate
Page 134:
Two kinds of horns in common use ar
Page 138:
FIGURE 2.13Geometry of a parabolic
Page 142:
FIGURE 2.14 Axisymmetric reflector
Page 146:
A transceiver antenna is a single a
Page 150:
The gain, in the axial mode, of a h
Page 154:
angles, spacecraft may shadow the s
Page 158:
3. The probability of both parallel
Page 162:
the baseband signal (more details a
Page 166:
matrix in the communications subsys
Page 170:
FIGURE 2.24Typical transfer charact
Page 174:
4. Iridium LCC (1997). Iridium Syst
Page 178:
3Earth StationsIn Chap. 2 we discus
Page 182:
The most popular forms of modulatio
Page 186:
Small earth stations are antennas w
Page 190:
FIGURE 3.2BPSK space diagram.Instea
Page 194:
OQPSKOffset QPSK (OQPSK) is a modif
Page 198:
FIGURE 3.7An 8-PSK space diagram.an
Page 202:
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 258:
3. For two independent sources, wit
Page 262:
FIGURE 3.21 A representation of mut
Page 266:
In practice, Eqs. (3.78) and (3.76)
Page 270:
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 326:
Follow the uplink procedure for the
Page 330:
Satellite:Frequencies:14.75 GHz up
Page 334:
6. For link to be maintained betwee
Page 338:
5.1 PRINCIPLES OF MULTIPLE ACCESSAs
Page 342:
neously, their transmissions collid
Page 346:
technique and would remain the most
Page 350:
FIGURE 5.4 Typical TDMA frame struc
Page 354:
FIGURE 5.6TDMA throughput for an IN
Page 358:
and transmits through the satellite
Page 362:
FIGURE 5.8FDMA total capacity respo
Page 366:
tion; that is, log e ð1 þ xÞ x t
Page 370:
REFERENCES1. Spilker, J.J. (1977).
Page 374:
6.1 CHANNEL CODINGNoise within a tr
Page 378:
where G is a generator matrix that
Page 382:
The syndrome is a single word of le
Page 386:
SolutionComparing (i) and (ii) with
Page 390:
Cyclic CodesCyclic codes are a subs
Page 394:
When errors occur in bursts, the nu
Page 398:
FIGURE 6.3Rate 1/2 convolutional en
Page 402:
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 458: can be used at separate user-to-net
Page 462: where0 n 40 m 246n þ m 24ð8:
Page 466: elationship between OSI and ISDN: t
Page 470: network and for networks to communi
Page 474: Copyright © 2002 by Marcel Dekker,
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
Page 508: REFERENCES1. Wu, W.W. (1989). Eleme
Page 512: Appendix ANotationsThe symbols have
Page 516: N sPP rP sP TRRðtÞR cR eR rR vSS
Page 520: g Central anglez Channel gainZ Ante
Page 524: AttenuationBandwidthBearer serviceB
Page 528:
Frequency divisionmultiple accessFr
Page 532:
MultiplexingNetworkOmnidirectionala
Page 536:
UplinkUser-to-networkinterfaceThe e
show all

View File - University of Engineering and Technology, Taxila

Create successful ePaper yourself

Delete template?

Save as template?