Approximate Ergodic Sum Capacity of Large-Scale Multi-User Distributed Antenna Systems

For a large-scale multi-user distributed antenna system (DAS), a series of fixed-point equations need to be jointly solved to obtain the ergodic sum capacity. The computational complexity quickly increases as the number of base station (BS) antenna clusters or the number of users grows, which makes it difficult to further analyze the effects of key system parameters on the average ergodic capacity. To address this issue, this paper proposes closed-form approximations of the ergodic sum capacity for large-scale multi-user DASs by solving the fixed-point equations using an iterative method, where a flexible tradeoff between accuracy and computational complexity can be achieved by adjusting the number of iterations. Simulation results show that compared to the existing approximations, the proposed ones are much more accurate, especially when the number of distributed BS antenna clusters is large.