Spectral efficiency analysis of large-scale distributed antenna system in a composite correlated Rayleigh fading channel

In this study, the downlink spectral efficiency of multi-cell multi-user large-scale distributed antenna systems (DASs) with pilot contamination is studied in a composite correlated Rayleigh fading channel. Firstly, under a physical channel model, the equivalent channel model of large-scale DAS with pilot contamination is given. Secondly, based on the equivalent channel model, the closed-form expression is derived for the downlink achievable rate with maximum ratio transmission, and the ultimate rate is also given when the ratio of the total number of base station antennas to the number of users goes to infinity. Thirdly, the results are validated via numerical simulations. It is shown that the closed-form expression is very accurate, and the downlink achievable rate of the large-scale DAS is much larger than that of the co-located massive multiple-input multiple-output (MIMO) with the same antenna configuration.