The Design Of Uplink MU-NIMO Receiver In LTE Systems

With the coming of Mobile Internet era, mobile access to Internet for obtaining messages has become the necessary demand of the modern society, which makes mobile communication system with faster data rates badly in need. While OFDM, MIMO and other advanced communication technologies had been adopted in the LTE system, the peak rate, transmission delay and spectrum utilization of this system have reached a new level. A new kind of MIMO technology is proposed in LTE system, which is named multi-user MIMO.MU-MIMO also can maintain its advantages in case of low-cost UE with few antennas. This paper mainly research on MU-MIMO in LTE system.Firstly the resource structure of the LTE uplink, MIMO signal model, multi-user pairing strategies were studied based on the LTE uplink protocols,. Then, the key technologies of the LTE uplink were researched, which consist of de-multiplexing reference signal, speed estimation algorithm and reception technology. The de-multiplexing reference signal includes ZC sequence conjugate multiplication, forced to zero, IDFT, temporal filtering, time-domain cyclic shift, DFT and zero truncated processing process. Final performance of the system would be affected by the speed of the users; a joint estimation algorithm is proposed based on frequency domain correlation method and experience method in this paper. There are two channel equalization technologies-the MMSE channel equalization technology and serial interference cancellation iterative channel equalization technology were studied in this paper. Finally, the MU-MIMO scheme is implemented in LTE uplink. The complete PUSCH link is set up according to the LTE physical layer protocol, which including bit processing module, symbol processing module of transmitter and front processing module, pilot frequency processing module and bit processing module of receiver. The performance of it was evaluated by simulation in MATLAB as well.