Study On Multiple User MIMO Wireless Relay Communication

MIMO technology can increase the system capacity of communication significantly with the spectrum bandwidth and the transmission power not increased. The wireless relay technology can overcome the problem that the signal decreased significantly with the increase of transmission distance due to the large-scale fading, and improve the system capacity and coverage of the wireless network. The MIMO wireless relay technology is an effective integration of the two technologies and has become an important technology in4G This paper studies the schemes for point-to-multipoint MIMO wireless relay communication system and multi-point-to-multipoint MIMO wireless relay communication system, with emphasis on the realization of the scheme and the antenna configuration constraints while trying to obtain the degree of freedom as high as possible.This paper firstly presents a scheme based the precoding and network coding to realize the communication of point-to-multipoint technology MIMO wireless relay communication system. The SSA(signal space alignment) technology and NB(null beam-forming) technology is utilized in this scheme to design the precoding matrix to eliminate MUI(multiple user interference), and RAS(receive antenna selection) technology is also adopted in this scheme to realize one source node communicating with multiple destination nodes with the same time and same frequency, improving the rate of the communication system and the DOF (degree of freedom) greatly. Besides, the RAS(receiving antenna selection) techniques has been adopted to extend the antenna configuration conditions, which make the antenna configuration conditions more available and can be chosen flexibility.This paper also presents an optimized DOF scheme, which can realize multiple nodes communicating with each other through the help of a relay node with the same time and same frequency. A method of data stream packet is utilized in this scheme, that is, the original stream data is decomposed into a parallel multi-stream data to be transmitted in the case of antenna configuration conditions allowed. This scheme can achieve a multiple-directional relaying and realize each pair of transmission partner communicating multiple independent information streams, improving the rate of the communication system and the DOF greatly. Besides, the dimension of the independent information streams can be selected dynamically according to communication demand in the actual communication scene. The numeral result shows that the scheme can improve the DOF and the rate of the communication system.