空时分组码多载波码分多址系统的空时多用户检测

针对传统的空时编码码分多址系统利用训练序列求解信道信息将导 g致频谱资源浪费这一问题,提出了一种矢量信道冲击响应(VCIR)的盲估计算法,它适用于基站使用多天线的空时分组码多载波码分多址(STBC MC CDMA)系统.与已提出的其他盲VCIR估计算法不同,此算法可以在每用户只使用一个扩频码时实现盲估计,因而不会降低系统中的最大活动用户数.基于估计出的 VCIR,为基站使用多天线的 STBC MC CDMA系统构筑了相应的空时多用户检测器.在系统的基站端使用多天线时,该检测器的活动用户数上限比使用单天线时的对应值有成倍的增加,在用户端使用空时分组码,可以更好地利用发射分集,提高信息的传送速率.仿真结果表明,该检测器不仅可以使用户容量达到系统活动用户数的上限,而且在活动用户数为14、相同信噪比的情况下,使用单根接收天线可以使系统误比特率降低40%.

Space-Time Multiuser Detection for Code-Division Multiple Access Systems Based on Space-Time Block Coding

Focusing on the problem that conventional space-time coding systems resolve the channel state information by exploiting training sequences and lead to consumption of bandwidth resource, a blind vector channel impulse response (VCIR) estimation algorithm was proposed, which is suitable for the multi-carrier code division multiple access (MC-CDMA) systems based on the space-time block coding (STBC) with multiple receiving antennae at the base station. Unlike other blind VCIR estimation algorithms, the proposed algorithm can implement the blind estimation when each user only employs one spread code. Therefore, the maximum number of active users can not be decreased. Successively, a corresponding space-time multiuser detector was constructed according to the estimated VCIR for the base station with multiple receiving antennae. When applying STBC to the user side, the transmit diversity can be utilized better and the transmit rate is increased. Computer simulation results show that the number of active users not only can be reached to the upper bound by the detector, but also the bit error rate can be decreased by 40% with one receiving antenna in the case that the active users are of 14 and the signal to noise ratio is the same.