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1、期末考试,考试时间：2013年6月26日下午答疑时间：另行通知,期末考试,考试形式：闭卷、英文试卷、英文答题试题类型：判断题 填空题 综合题成绩构成：平时成绩10%、期末考试90%平时成绩：出勤、作业课程网站：http:/,复习提纲,Chapter 7 Spread-Spectrum ModulationSpreading sequences(Pseudo-noise sequence)The period of a PN sequence is at most 2mm-sequencemethods of generation-primitive polynomial of degree m
2、period N=2m-1Balance propertyRun propertyCorrelation property,复习提纲,Chapter 7 Spread-Spectrum ModulationGold sequenceperiod=2m-1number of sequences=2m+1 generation:a preferred pair of primitive polynomials g1(X)and g2(X)A preferred pair of primitive polynomials whose cross-correlation function has a
3、magnitude less than or equal to 2(m+1)/2+1 for m odd 2(m+2)/2+1 for m even and n 0 mod 4,复习提纲,Chapter 7 Spread-Spectrum Modulation2.Principles of spread spectrum modulation Bandwidth minimum bandwidth necessary secure communication,sacrifice the efficiency of channel bandwidth&transmit power Primary
4、 advantage-reject interference,复习提纲,Chapter 7 Spread-Spectrum Modulation3.Two commonly used types:DS(direct sequence)&FH(frequency hopping)DS/MPSK:narrowband data sequence-noiselike wideband signalFH/MFSK:carrier frequency hopped over a number of frequencies in a pseudo-random manner Slow-Frequency
5、Hopping&Fast-Frequency HoppingBoth of the above two techniques rely on the use of a pseudo-noise sequence(PN sequence)Comparison:FH bandwidths DS bandwidths most FH/SS systems use non-coherent detection,复习提纲,Chapter 8 Multiuser Radio CommunicationsMultiple-access techniquesDefinition:simultaneous us
6、e of a communication channel by a number of usersFour basic types of multiple accessFrequency-division multiple access(FDMA)Time-division multiple access(TDMA)Code-division multiple access(CDMA)Space-division multiple access(SDMA),复习提纲,Chapter 8 Multiuser Radio CommunicationsSatellite communications
7、Uplink(earth terminal satellite)&downlink(satellite another earth terminal)6/4GHz or 14/12GHzline-of-sight radio propagation for the operation of its uplink and downlink additive white Gaussian noise(AWGN)channel modeloffers global coverageTDMA used widely in digital satellite communications,复习提纲,Ch
8、apter 8 Multiuser Radio CommunicationsRadio link analysislink(power)budget analysis-the totaling of all the gains and losses incurred in operating a communication linkTwo particular values of Eb/N0:1.Required Eb/N02.Received Eb/N0link margin(8.2),复习提纲,Chapter 8 Multiuser Radio CommunicationsRadio li
9、nk analysiseffective aperture(8.11)The path loss(8.15)Free-space lossRatio of received carrier power-to-noise spectral density(8.31),复习提纲,Chapter 8 Multiuser Radio CommunicationsWireless communications(mobility and the multipath phenomenon)reverse link(uplink):mobile base stationforward link(downlin
10、k):base station mobileoffers mobility(communicate with anyone,anywhere)tetherless(total freedom of location is permitted)the presence of multipath(no longer the idealized AWGN channel model)Doppler-shift,复习提纲,Chapter 8 Multiuser Radio CommunicationsWireless communications(mobility and the multipath
11、phenomenon)co-channel interferencemultipath fading delay spreadspecialize techniques used,such as:diversityadaptive array antennasRAKE receiver,signal-dependent phenomena,复习提纲,Chapter 8 Multiuser Radio CommunicationsAdaptive antennasdelay spread coherent bandwidth BcDoppler spread coherence timemult
12、ipath,delay spread(ISI)and co-channel interference(CCI)cancel the CCI array signal processor(spatial)cancel the ISI linear equalizer(temporal)space-time processor,which combines temporal and spatial processing,复习提纲,Chapter 9 Fundamental Limits in Information TheoryEntropy-basic measure of informatio
13、nAmount of information bits(9.4)PropertiesEntropy-mean of I(sk)bits/symbol(9.9)Boundary(9.10),复习提纲,Chapter 9 Fundamental Limits in Information TheorySource coding and data compaction(1)Average code-word length(9.18)Source-Coding Theorem,Shannons first theoremGiven a discrete memoryless source of ent
14、ropy,the average code-word length for any distortionless source encoding scheme is bounded as(9.20)Data compaction,lossless compression of data,复习提纲,Chapter 9 Fundamental Limits in Information TheorySource coding and data compaction(2)Prefix Coding Huffman Coding Huffman tree as high as possible or
15、as low as possible?Lempel-Ziv Coding,复习提纲,Chapter 9 Fundamental Limits in Information TheoryMutual information-channel capacity(1)conditional entropy(9.41)Mutual information,复习提纲,Chapter 9 Fundamental Limits in Information TheoryMutual information-channel capacity(2),(9.59),Subject to,and,for all j,
16、复习提纲,Chapter 9 Fundamental Limits in Information TheoryChannel Coding Theorem,Shannons second theorem,(i)If,Exists a coding scheme.C/Tc-critical rate,(ii)If,Not.,(9.61),(9.62),average information rate channel capacity per unit time,For BSC,if code rate r channel capacity C,codes do exist such that t
17、he average probability of error is as small as we want it.,复习提纲,Chapter 9 Fundamental Limits in Information TheoryInformation Capacity Theorem,Shannons third theoremdifferential entropy of a continuous random variable X,(9.66),The information capacity of a continuous channel is given by,There is a m
18、aximum to the rate at which any communication system can operate reliably(i.e.,free of errors)when the system is constrained in power.,复习提纲,Chapter 9 Fundamental Limits in Information TheoryRate-distortion theory-source coding(1)Source coding with a fidelity criterionRate Distortion Function The sma
19、llest coding rate possible for which the average distortion not to exceed D.,(9.131),subject to the constraint,(9.132),复习提纲,Chapter 9 Fundamental Limits in Information TheoryRate-distortion theory-source coding(2)Signal compression(i.e.,solving the problem of source coding with a fidelity criterion)
20、data compression(if lossless)data compaction(such as Huffman coding,Lempel-Ziv coding)data encryption,复习提纲,Chapter 10 Error-Control CodingLinear block codes(Cyclic codes)generator matrix(polynomial)parity-check matrix(polynomial)Syndromeminimum distance dminEncoder for cyclic codes,复习提纲,Chapter 10 E
21、rror-Control CodingConvolutional codesGenerator polynomialGraphical formsCode TreeTrellis State DiagramThe Viterbi algorithmCatastrophic code,复习提纲,Chapter 10 Error-Control Coding3.Compound codesTurbo Low-density parity-check codes Irregular codes4.TCM Combine coding and modulation to attain a more effective utilization of the available bandwidth and power.,预祝同学们考出满意的成绩！,
