Zero-forcing precoding and antenna selection research for coordinated multiple point transmission

Communication system capacity is greatly improved by multiple input multiple output (MIMO) wireless transmission technology. In a commercial cellular system, the entire network is essentially an interferencelimited system. While the problem of other-cell interference (OCI) is inherent in cellular systems, its affect on MIMO transmission is more significant, because each neighboring base station (BS) antenna element can act as a unique interfering source. Because of the fast improvement in processing capability at BSs and the increase in the backhaul capacity, coordinated multi-cell MIMO communications with cooperative processing among BSs have attracted a significant amount of interest in recent years. Most of the current work is focused on the study of system capacity, but the equivalent SNR of each user (i.e., fairness) has an important influence on system performance, such as the frame error rate. Considering the single antenna configuration for the user, the system capacity and fairness based on a zero-forcing precoding design are studied in the case of the total power and per antenna power constraints. The fairness is analyzed for the two types of power constraints, and a closed solution is given. Considering the multiple antenna configuration for the user, the receive antenna selection algorithm, which maximizes the channel norm, is used to reduce the computational complexity. Thus the case for the user with a multiple antenna configuration is transformed into the case for the user with a single antenna configuration, The fairness algorithm for the user with a single antenna is still applicable. The simulation results show that multi-cell collaboration with zero-forced precoding can significantly improve system performance. In the same zero-forced precoding, different power allocation strategies have a significant affect on system capacity and fairness. Compared with the user with a single antenna, the antenna selection algorithm can enhance system capacity and fairness. The tradeoff between user fairness throughput and maximum system throughput is considered, and simulation results are also given.