Opportunistic downlink scheduling with fair resource sharing for distributed antenna systems

In this paper, we propose a novel cumulative-distribution-function-based scheduling (CS) with flexible-beam transmissions (CSFB) as an opportunistic downlink scheduling with fair resource sharing for distributed antenna systems (DASs). Taking advantage of the spatially distributed nature of remote antenna units (RAUs) in DASs, CSFB dynamically assigns a different weight for each user-RAU pair and adjusts the number of beams for transmissions based on the channel conditions, in order to increase the probability that each RAU can contribute to the throughput of users located near it by efficiently exploiting spatial multiplexing gain. Furthermore, by simply setting a single threshold for each RAU, which is applied for user selection, CSFB maintains fair resource sharing constraints. This simple setting greatly facilitates the scheduler design. Thus, our proposed CSFB can exploit the multiuser diversity gain provided by the independent channel fading of multiple users, as well as the spatial multiplexing gain through the effective utilization of distributed RAUs. Simulation results demonstrate that CSFB achieves a better throughput performance than CS with all-beam transmissions and CS with single-beam transmissions, while satisfying the fair resource sharing constraints.