Sum Rate and Power Consumption of a Circular-Layout Distributed Antenna System with MMSE Receivers

The distributed antenna system (DAS) is considered as a promising architecture for future wireless access. This paper describes the uplink of a power-controlled circular-layout DAS (CL-DAS) with minimum mean-square error (MMSE) receivers. Results from random matrix theory are used to show that for such a DAS, the per-user sum rate and the total transmit power both converge as the number of users and antennas goes to infinity with a constant ratio of antennas to users. The relationship between the asymptotic per-user sum rate and the asymptotic total transmit power is given for all possible values of the radius of the circle on which antennas are placed. This rate-power relationship is then used to find the optimal radius. With this optimal radius, the CL-DAS is proved to offer a significant gain compared with a traditional co-located antenna system. Simulation results demonstrate the validity of the analysis and the superiority of the DAS.