Also , new expression of ser of mqam in frequency selective fading channel with rake combining is obtained , and throughput performance adaptive mqam with rake receiver in multipath rayleigh fading channel is analyzed 本文还得到了mqam在频率选择性衰落信道中采用rake合并新的误码率表达式，并对采用rake接收的自适应mqam在多径瑞利衰落信道中吞吐量性能进行分析。
Modifying log - map algorithm to be suitable for rayleigh fading channels , and researching the performances of turbo codes over rayleigh fading channels based on above deriving . simulation results show that turbo codes exhibit superior error correction performance over fading channels 在此基础上，进一步研究turbo码在瑞利衰落信道中的性能，仿真结果表明， turbo码具有很强的抗衰落和抗多径效应能力。
The simulation result shows that : the performance of the proposed scheme is improved with comparison to pccc and sccc on both awgn channel and the rayleigh fading channel . in awgn channel , it is about same if the snr is low , if the snr is high , the improvement is 0 . 2 ~ 0 . 5db 结果表明：本方案的误码率性能与并行级联码和串性行级联码相比，在高斯白噪声信道上，低信噪比时几乎相同，高信噪比时有0 . 2 0 . 5db的改善。
They still need to be studied . this thesis systematically studies the performances of turbo codes over both awgn channels and rayleigh fading channels , and discusses the applications of turbo codes in still image transmission systems . some significative conclusions are obtained 本文系统地研究了turbo码在awgn信道和rayleigh衰落信道下的性能，并探讨了turbo码在静止图像传输系统中的应用，取得了一些有意义的成果。
Then , analytical expressions of the bit error rates are derived under rayleigh fading model and multi - path rayleigh fading channel model . analytical and simulation results are compared . the multi - path performance of the non - coherent dcsk system is also compared with that of the coherent csk system 接着对非相干dcsk系统在瑞利衰落及多径瑞利衰落信道下进行性能分析,通过仿真实验来验证理论分析结果,并与相干csk系统的抗多径衰落性能比较。
Simulations results under rayleigh fading channel and on / off traffic model show that asama protocol can effectively support the application of smart antennas and provides high channel utilization and low delay . in chapter 5 , we propose a qos ( quality - of - service ) - supported adaptive slot allocation multiple access ( qasama ) protocol 在考虑多波束智能天线，及话音与数据业务特点的基础上，提出了提供qos保障的自适应时隙分配多址接入协议( qasama 、 。
Turbo codes represent the new code structures , which consist of pccc ( parallel serially convolutional code ) and sccc ( serially concatenated convolutional code ) . in this paper , the background of turbo codes are firstly introduced , which includes the base principle of error correction code 、 block code and convolutional code ; the principle of turbo code and the iterative decoding is secondly expanded ; the key decoding algorithm : a revised map algorithm and iterative decoding theory are detailed ; then , a new turbo code structure : hccc ( hybrid concatenated convolutional code ) is presented , and the capacity of this code method is analyzed , the average capacity upper bound is derived ; at last , this code is simulated on awgn ( additive white gaussian noise ) channel and rayleigh fading channel 本文首先介绍了turbo码的背景知识，包括差错控制的基本原理、分组码和卷积码；然后阐述了turbo码的基本原理，包括turbo编译码器结构及迭代译码原理；较为详细地描述了关键的译码算法： ?种改进的最大后验概率( map )译码算法及迭代译码算法；提出了一种新的turbo码结构：混合turbo码(混合级联卷积码) ；并用编码性能联合界分析方法对混合turbo码进行了性能分析，得出了其平均性能上界；并在高斯白噪声信道和瑞利衰落信道上分别作了一些应用研究及计算机仿真实验。
Section 4 researches on pilot symbol aided space - time 2d rake receiver in rayleigh fading channel . two kinds of 2d - rake receivers are proposed , one is the interference zeros force 2d - rake receiver ( zf - 2drake ) . simulation results reveal zf - 2drake has the better performance than the conventional 2d - rake receiver 研究了rayleigh信道下2种导频辅助的空时2d - rake接收机结构:干扰置零2d - rake接收机( zf - 2drake )和基于空时信道估计的时空级联2d - rake接收机( spce - 2drake ) ,推导了它们的误码率性能。
Under rayleigh fading channel , we also simulated and compared ber in siso 、 simo and mimo systems . secondly , based on careful study the ber and the channel capacity under white noise channel under mpsk modulation when the channel is rayleigh fading , we duduced the expressions of stbc ’ s ber and channel capacity under rice and nakagami fading . and also analysed the performances through numerical simulation using matlab to testify the exactitude of the dudeced expressions . finally , there exists an error floor of stbc through studying on its performance on time - selectiv fading channel . we analysed the reason and proposed two new decode combination scheme to eliminated the error floor and the performance of stbc on time - selective fading channel is improved . and also compared the two scheme ’ s complication and snr gain 这些结果大部分是闭式结果,能比较准确地衡量空时块码的性能,并对不同衰落的性能做了相互比较,其结果对空时块码的实际应用具有一定的指导意义。实际的信道是时变的,分析了空时块码在时间选择性衰落信道中产生误差地板效应的主要原因是存在码间干扰( isi ) ,在此基础上提出了两种能消除误差地板效应的译码合并方案,并对这两种方案的复杂度和信噪比增益进行了比较。
Abstract : by comparing the channel capacities hetwem orthogonal space - time block coding and multi - antenna array system over rayleigh fading channel , some capacity loss for orthogonal space - time block coding is obtained , which is a function of the code rate , the rank of channel matrix and the number of transmitter and receive antennas , although the system of orthogonal space - time block codes is simple and easy to implemented . if is also shown that there is no capacity loss only if both the code rate and the channel matrix rank are all one 文摘:在研究瑞利衰落条件下正交空时分组编码信道容量的基础上，将其与多发送多接收天线系统的信道容量进行了比较.比较结果表明，正交空时分组码虽编码简单，易于实现，但在信道容量方面存在较大的损失，损失的程度与编码码率、信道矩阵的秩及收发天线数等因素有关.进一步研究表明只有当编码码率和信道矩阵的秩都为1时，才没有信道容量的损失
