Uplink spectral efficiency analysis of multi-cell multi-user massive MIMO over correlated Ricean channel

In this study, the performance of uplink spectral efficiency in massive multiple input multiple output (MIMO) over a spatially correlated Ricean fading channel is presented. The maximum ratio combining (MRC) receiver is employed at the base station (BS) for two channel estimation methods. The first method is based on pilot-assisted least minimum mean square error (LMMSE) estimation, whereas the second is based on line-of-sight (LOS). The respective analytical expressions of the uplink data rate are given for these two methods. Because of the existence of pilot contamination, the uplink data rate of the pilot-assisted LMMSE estimation method approaches a finite value (we call it the asymptotic rate in this study) when the BS antenna number is high. However, the data rate of the LOS method is linear with the number of BS antennas. The expression of the uplink rate of the LOS method also shows that for a Ricean channel, the spatial correlation between the BS antennas may either decrease the rate or increase the rate, depending on user location. This conclusion explains why the spatial correlation may increase rather than decrease the data rate of pilot-assisted LMMSE. We also discuss the power scaling law of the two methods, and show that the asymptotic expressions of the two methods are the same and both are independent of the antenna correlation.