Research On Asymptotic SINR And Power Gain In Massive MIMO Systems

With the popularity of smart phones and rapid development of IoT applications, the future communication systems need higher availability and reliability. Current wireless communication exists those disadvantages of low spectrum resources and excessive power consumption. The future trends of mobile communications will be more efficient, higher speed, more intelligent. Traditional physical layer technologies (e.g. coding), which efforts to improve the gain, performs worse than improving the base station, such as increasing antennas, bandwidth, and base stations. Massive MIMO systems increase antennas at the base station side, by using the spatial channel resources, increase the diversity and the data transmission rate. Massive MIMO systems improve system performance by using a large number of redundant antennas, it can achieve high spectral and energy efficiency simultaneously; will become the core technology of 5G. Massive MIMO can reduce transmit power and interference, and improves the data rate and reliability. Most importantly, with the number of base station antennas growing, small-scale fading and thermal noise can be averaged out. This paper focuses on researching and analyzing on the asymptotic SINR and power scale gain of massive MIMO systems. The main contents are summarized as follows:First of all, the law of large numbers applies to point-to-point MIMO and multi-user MIMO scenario of massive MIMO, then we can introduce approximate orthogonal rows of channel matrix between the user and the base station, and analyzed that channel change in large MIMO systems which brings by precoding.Secondly, in the paper, the downlink precoding of single-cell massive MIMO systems has been researched, the closed expression of system’s downlink asymptotic SINR under four precoding (MRT, ZF, MMSE, RCI) have been derived; and the parameters that affect system performance has been obtained. The simulation results showed correctness of asymptotic SINR expression in massive MIMO system, and compared system performance differences among various precoding, then we can draw a conclusion that RCI precoding performs best than any other kind.Finally, this section introduced the uplink asymptotic SINR of the massive MIMO under single-cell and multi-cell scenarios, proposed power scale gain. The simulation validated the existence of power scale gain and the effect of the uplink asymptotic SINR by the numbers of base station antennas.