多用户MIMO系统下行链路的随机多波束复用技术

该文提出了一种随机多波束多用户复用技术，充分利用多用户分集以及基站多天线的空间自由度来提高系统吞吐量。不同于传统的随机波束形成技术，该技术首先在给定预编码码本内随机选取一个码字，然后调度多个空分复用用户以及其余预编码矩阵。该文采用了一种逐次调度的方式，第一次训练调度一个主发送用户并确定一个次发送预编码矩阵，通过第二次训练选择次发送用户，这种方式能以很小的反馈开销有效控制复用用户之间的相互干扰。同时，该文所提技术能进一步推广到用户具有不同天线配置的异构情形。仿真结果表明，该文技术在具有不同相关性的信道环境下都能获得较优的系统吞吐量。

A Random Multi-beam Multiplexing Technique for the Downlink of Multiuser MIMO System

A novel random multi-beam multiplexing technique is proposed in this paper, which improves the system throughput by exploiting both multiuser diversity and spatial freedom degrees of multiple transmit antennas at the base station. Different from conventional random beamforming techniques, the proposed one first randomly selects one codeword from a given codebook of precoding matrices, then schedules several spatially multiplexing users and determines other precoding matrices. A successive scheduling algorithm is proposed, which selects a main transmit user and determines the secondary precoding matrix for the other user in the first training phase, then the secondary transmit user is selected based on the secondary precoding matrix in the second training phase. This successive scheduling way is capable of fully suppress the mutual interference between multiplexing users at cost of little feedback overhead. Also, the proposed technique can be extended to heterogeneous cases where users may be configured with different number of receive antennas. Simulation results demonstrate that the proposed technique achieves good throughput over different correlated channel environments.