Research Of Non-coherent MIMO Detection Technology For Multi-user Downlink

Non-coherent MIMO space division multiplexing technology based on energy detection does not require accurate and instantaneous channel state information for signal demodulation,and has the characteristics of resisting random phase interference and immunity to doppler shift.It has become one of the key technologies to achieve large capacity and high reliability communication in high-speed mobile environment.Multi-user MIMO technology can be used to communicate with multiple users at the same time and the same frequency by means of space division multiple access,which can multiply the capacity and spectrum efficiency of communication system.The existing research on non-coherent multi-user multi-antenna detection technology mainly focuses on multi-user SIMO uplink system.Even though a few literatures have studied non-coherent multi-user MIMO downlink system,they still mainly rely on differential space-time coding,and the spatial multiplexing gain is not high.Applying non-coherent MIMO space division multiplexing technology based on energy detection to multi-user MIMO downlink system can realize non-coherent multi-user MIMO downlink transmission in space division multiplexing mode,thus improving the capacity of the system.However,energy detection will cause nonlinear interference between users.Aiming at the multi-user MIMO downlink system based on the space division multiplexing,the algorithms of precoding are designed to improve the reliability of the system,so that multiple users can communicate at the same time.The research contents of this paper are as follows.1.The research statuses of point-to-point MIMO non-coherent detection technology and non-coherent multi-user MIMO technology at home and abroad is described,the models of single-user MIMO and multi-user MIMO downlink system are briefly described,and several classic multi-user MIMO precoding technologies are introduced.2.The MIMO channel model in high-speed mobile environment is given.Focusing on the characteristic of resisting random phase interference of FSK and MFSK non-coherent receivers,the MIMO FSK random phase detection algorithm and MFSK energy detection algorithm are derived.The performance of resisting random phase interference and immunity to doppler shift in rice fast fading channel are analyzed by simulations.3.To solve the problem of multi-user interference in the downlink multi-user MIMO non-coherent energy detection system,the linear precoding technology is proposed to eliminate the multi-user interference.It is proved by theory and simulation that precoding is still an effective technique to eliminate multi-user interference in nonlinear multi-user MIMO system based on square law processing.4.In order to solve the problem that the transmitter is difficult to obtain accurate and instantaneous channel state information in the high-speed mobile environment,a non-coherent precoding algorithm is proposed.The precoding algorithm based on the real channel state information at the transmitter can reduce the cost of obtaining the precoding matrix,and the user can realize the interference free transmission after the random phase detection.