Uplink Performance Analysis Of Large Scale MU-MIMO Systems

Mobile communications come into the4G era. Two key techniques, MIMO and OFDM wereintroduced into the4G. MIMO technique, which can provide great potential for improvement ofthe spectral efficiency and transmission performance of wireless links, has been widelyresearched and applied. Recently, experts and scholars also proposed the large scale MIMOtechnique, that scales up MIMO by an order of magnitude compared to current state-of-art.Meanwhile, it can greatly enhance the overall performance of the system. Therefore, it’simportant to do further research on the massive MIMO.This paper mainly considers the uplink performance of large scale MIMO system, assuminga base station has perfect channel state information (CSI) and serves many single antennausers.The data is detected by the linear receivers. Firstly, this part considers a multi-usersingle-cell system, the closed-form expression of uplink rate as well as a lower bound on theachievable rate are derived when the number antennas of BS tend to different values. We furtherstudy the asymptotic system performance in the regimes of different SNR, large numberantennas of BS. Meanwhile we also discuss the performance comparison of MRC, ZF detectionalgorithm. Secondly, on the basis of the previous research, we consider a multi-user multi-cellsystem, the data is detected by ZF receiver. This part also derives the uplink rate expression anda lower bound rate, as well as studies the asymptotic system performance in the regimes ofdifferent SNR, large number antennas of BS. Finally, the part discusses the impact of frequencyreuse factor and intercell interference on the multi-cell system, and gives the correspondingconclusions. The given simulation results verify the theoretical analysis, show that increasing thetransmit power of each user can’t improve the system performance. Instead, by increasing thenumber of BS antennas, the effects of interference and noise can be reduced. Meanwhile, withvery large antennas at BS, the transmit power of each user can be inversely proportional to thenumber of BS antennas while maintaining a desired QoS. Therefore, compared to conventionalMIMO technology, the large scale MIMO technology can significantly improve systemperformance.