Space-time spreading (STS) and orthogonal transmit diversity (OTD) are towtransmit diversity schemes proposed by cdma2000 standard. In this paper, performance comparisonanalysis of the two transmits diversity schemes in multipath channel under multiuser situation arecarried out. Link level simulation in forward link cdma2000 is performed in IMT-2000 channel.Performance analysis and simulation results show that the performance improvement provided STS overOTD decreases as the increase of propagation path number and decrease of the user number.
为了在数字芯片上以低硬件复杂度实现Polar码的译码算法,对Polar码连续消除(SC)译码算法接收符号和SC译码输入的初始比特对数似然比(LLR)的量化问题进行了研究.分析了接收符号量化区间和量化比特数对Polar码SC译码性能的影响.对译码输入初始LLR,从均匀量化和非均匀量化两方面,并对非均匀量化采用了归一化非均匀量化和小数非均匀量化2种方式,分析了初始LLR的量化对Polar码SC译码性能的影响.仿真结果表明,分别对接收符号和初始LLR采用区间[-4,4]和区间[-20,20]上的6 bit均匀量化,就可以使Polar码SC译码算法的误比特率(BER)性能损失在小于0.1 d B的同时,具有更简单的硬件实现复杂度.
To improve performance of receiver, the pilot channel is added to reverse channels of CDMA2000 In this paper, the structure of reverse channels is outlined and the principle of Rake receiver is discussed, then the model of the Rake receiver is set up and some computer simulations are performed.
