Downlink massive distributed antenna systems scheduling

This study investigates the scheduling problem for a single-cell downlink distributed antenna systems (DASs) with a massive number of remote access units (RAUs). To reduce signalling overhead under limited backhaul capacity, the authors make use of local long-term channel state information (CSI) in coordinated scheduling design. They first derive the ergodic rate expressions for both the single RAU transmission and the cooperative RAU transmission modes as functions of long-term CSI. Then greedy scheduling algorithms (GSAs) aiming for the maximum ergodic sum rate for the massive DAS using long-term CSI are proposed. To mitigate the intra-cell interference, a two-stage GSA with hybrid transmission mode is devised. Asymptotic analysis reveals that as the number of RAUs goes to infinity, intra-cell interference can be effectively mitigated. Simulation results verify the analysis and demonstrate that the two-stage GSA exhibits a higher ergodic sum-rate.