Research On Receive Antenna Selection And User Selection For MIMO Systems

With the rapid development of wireless communications, the conflict between the limited wireless resource and the increasing Quality of Service (QoS) requirement of users becomes more and more urgent. As a result, how to utilize wireless resource efficiently becomes more and more important. Nowadays multi-antenna technology is regarded as one of the most effective methods to improve the spectrum utilization.Multiple input multiple output (MIMO) technique has received extensive attention for its technical predominances as one of the key technologies of the future communication systems. The research has shown that the MIMO technology could provide spatial diversity and spatial multiplexing for wireless communication systems. Spatial diversity technique is a powerful technique to mitigate fading in wireless links. Spatial multiplex gain can provide a linear increase scaled to the antenna number without additional power or bandwidth, which enlarge the frequency spectral efficiency. However, the employment of multiple antennas at transmit/receive end increases the additional hardware and thus the cost required in the form of radio frequency (RF) chains. Antenna selection is a low cost and low complexity technique to capture many advantages of MIMO systems that can barter very little lost of system performance for the great decrease of RF cost, making MIMO system not fully limited by RF cost.However, the research emphasis has transferred from single user to multiuser MIMO system. The multiuser MIMO system can communicate with multiple users without extra time slots and frequency resources and can provide much more channel capacity compared with the single user MIMO system. How to optimize the assignment of system resources without increasing the consumption of transmission power and sacrificing the bandwidth, and how to fulfill the quality of service (QoS) of different users in a multi-user system are the practical problems to be solved.Multiuser MIMO system can provide multiuser diversity. Different users experience different channel fading. while one user is in deep fading, others may have good channel condition. User selection is a very important technique for MIMO systems that can utilize multiuser diversity to improve system performance. However, user selection usually selects users with better channel condition. In order to ensure fairness among different users, scheduling is required to manage the users' access to the resources.Antenna selection algorithm in single MIMO systems is firstly studied in this dissertation, then for multiuser MIMO systems, the user and antenna selection and scheduling algorithm is proposed. In general, the main achievements of this dissertation are listed as follows:(1)A simple receive antenna selection algorithm is proposed. This algorithm is based on the analysis of the lower bound of SNR and the solved by convex optimization tools. It can achieve almost the same performance as the optimal selection algorithm.(2)An efficient user selection algorithm based on the maximization of SLNR for multiuser MISO downlink system is proposed which can avoid the couple problem among different users. Based on the method, a fair scheduling scheme is further given to ensure fair service to all users making users with worse channel condition have chance to be served.(3)Propose a joint user and antenna selection algorithm for uplink multiuser MIMO systems. The algorithm can select the right number of user and antenna to maximize the channel capacity. The performance of the proposed algorithm is near to the optimal method in different SNRs and with different number of users.Based on above analysis, antenna selection methods for the single user MIMO systems and user selection method with scheduling technique for the uplink and downlink multi-user MIMO systems are studied in this dissertation. Finally, the problems to be solved in this research field and future research topics are summarized.