DS-CDMA系统新的空时并联结构 及二维自适应DBF算法

针对直接序列扩频码分多址(DS-CDMA)移动通信接收系统,本文提出了一种新的空时二维信号处理结构,这是一种"智能天线与瑞克(RAKE)接收机的并联连接"(PI-SA&RR)结构.基于PI-SA&RR结构,提出了空时二维自适应数字波束形成(ST2-DADBF)算法.与"二维RAKE接收机"(2-DRR)相比,ST2-DADBF算法不需要对延时-波达方向(DOA)进行估计就能够获得最优空-时域联合输出.与"导频符号辅助相干自适应天线阵列分集接收机"(PSA-CAAADR)相比,ST2-DADBF算法能够使智能天线和RAKE接收机联合参与自适应算法,不需要对RAKE分支信道参数进行估计,是一种真正的二维自适应算法.针对多用户移动通信系统,同时考虑到信道的时延扩展和空间角度弥散的影响,本文给出了一种接收信号的通用模型,基于该模型对ST2-DADBF算法进行了计算仿真.仿真结果表明,ST2-DADBF算法能够在空时二维域中捕获感兴趣用户的各个多径分量,并将这些多径分量同步相干合成,同时抑制其它用户在时域和空域形成的干扰,因而可获得良好的误码率(BER)性能.

A New Space-Time Parallel Interconnection and the 2-Dimension Adaptive Digital-Beamforming Algorithm for DS-CDMA Systems

For coded-division multiple access (CDMA) mobile communication receiving systems,a new space-time 2-dimension signal processing framework is presented in this paper,which is a kind of parallel interconnection of smart antenna and RAKE receiver (PI-SA&RR).Based on this framework the space-time 2-dimension adaptive digital-beamforming (ST2-DADBF) algorithm is given.Comparing with the 2-dimension RAKE receiver (2-DRR),the ST2-DADBF algorithm can implement optimal outputs of joint space- and time-domain without estimating delay-DOA's (Directions of Arrival).Comparing with the pilot symbol-assisted coherent adaptive antenna array diversity receiver (PSA-CAAADR),the ST2-DADBF algorithm is a genuine 2-dimension adaptive algorithm,which can combine smart antenna and RAKE receiver to perform adaptive algorithm without estimating parameters of RAKE fingers.Considering both effects of time-delay-dispersion and space-angle-dispersion of the channel,we present a general signal model for multiple-subscriber mobile communication system.Based on this model the computational simulations of the ST2-DADBF algorithm are done.Simulating results imply that the ST2-DADBF algorithm can catch each of the multi-path components of the interested user in 2-D space-time domain,and combine these components coherently and simultaneously,while suppress interferences caused by other users in time- and space-domain,hence improve bit error rate (BER) performance of the system.