Research Of MIMO Precoding In The Cognitive Radio Network

With the rapid development of wireless communication, modern mobile communication network is facing problems---types of communication services rapid increase, quality of communication services requires higher, wireless environment is more complex and spectrum resource limits etc.. In order to meet the requirements of high data transmission rate and high QoS, the new technology is researched to improve spectrum utilization. In recent years, MIMO technology has been widely applied to LTE network and significantly improves system capacity, spectrum efficiency and transmission reliability of wireless communication system through spatial diversity, multiplexing technology and so on. Cognitive radio technology allows unauthorized user/second user under access to primary network under certain conditions, which effectively improves the frequency spectrum utilization. Cooperative communication solves the fading from long distance transmission, multipath fading and shadow effect etc. The combination of MIMO technology, cooperative communication and cognitive radio effectively improves matrix gain, diversity gain, multiplexing gain of the system and the system spectrum utilization, and expand the coverage of the system.The precoding in cognitive MIMO network is studied in this paper, and precoding algorithms in cognitive MIMO network and cognitive multi-hop relay MIMO network are proposed. Meanwhile, the performance of the system is studied. The following three aspects are contained in this paper. Firstly, the MIMO precoding in classical traditional network, cognitive network and cooperative communication network are summarized. The classical MIMO precoding algorithms are researched by simulation comparison. Secondly, the cognitive radio network precoding algorithms are summarized and proposed the minimize mean square error prcoding algorithm. These precoding algorithms in terms of bit error rate and system capacity are compared based on simulation results. Finally, the MIMO precoding algorithm in cognitive relay networks is researched and the performance of cognitive multi-hop relay network is studied when the interference to primary users is constrained and transmission power is constrained.