多用户MIMO系统中连续块对角化预编码算法
Successive Block Diagonalization Precoding for Multi-User MIMO System

块对角化(BD)预编码是多用户MIMO(MU-MIMO)系统下行链路中广泛采用的线性预编码方案。当用户有多路数据流时，传统的BD预编码存在数据流间等效信道增益不平衡的问题。该文基于BD预编码算法，提出连续BD预编码(SBD)算法。新算法考虑天线间干扰提出新的干扰矩阵构造方法，连续地计算每根接收天线所对应的预编码矩阵。SBD预编码减小了由BD预编码引起的每个用户多路数据流之间有效信道增益的差距，提高了用户的平均误码性能。发射机采用空间分集的发送策略时，接收端进行合并，与BD算法相比，能够获得更多的分集增益。计算机仿真表明，在{2,2}*4的MU-MIMO系统中，当误码率为10^(-3)时，所提算法与现有BD算法相比，获得约2dB的性能增益。
Block Diagonalization (BD) is a common linear precoding technique for the downlink of multi-user MIMO(MU-MIMO) systems. A drawback of conventional BD is that the effective channel gain for each data stream can be severely unbalanced when each user has multiple data streams. In this paper, a new precoding scheme called successive BD (SBD) is proposed based on BD precoding by introducing a new construction scheme of interference matrices considering inter-antenna interference. The precoding matrix responding to each of the receive antennas is successively calculated. SBD precoding reduces the difference in effective channel gain between each user’s multiple data streams caused by the original BD precoding and improves the average bit error performance of the user. More spatial diversity gain can be obtained compared with BD precoding when precoding and combing are employed and spatial diversity transmission strategy is adopted. Simulations show that when the bit error rate is 10^(-3), the proposed method has about 2 dB gain over the conventional BD precoding in {2,2}*4 MU-MIMO systems