Opportunistic Downlink Scheduling With Resource-Based Fairness and Feedback Reduction in Distributed Antenna Systems

Despite increasing interest in distributed antenna systems (DASs), how to guarantee resource-based fairness in multiuser DASs remains largely unexplored. In this paper, we propose a novel cumulative distribution function (CDF)-based scheduling (CS) with flexible beam transmissions (CSFB) to guarantee resource-based fairness in DASs. With CSFB, to increase the probability that each remote antenna unit (RAU) can contribute to the throughput of users located near it, the probabilities of each user being selected for different RAUs and the number of beams for transmission are jointly adapted to the geographical distribution of RAUs. Thus, CSFB can efficiently exploit multiuser diversity realized by independent fading channels, as well as spatial multiplexing by effectively utilizing the distributed RAUs. To realize CSFB in practice, a one-bit-feedback scheme, i.e., CSFB-OB, is further proposed to reduce feedback overhead for user selection. We prove that both CSFB and CSFB-OB can satisfy resource-based fairness and derive the upper bound for the feedback overhead with CSFB-OB. Simulation results show that CSFB and CSFB-OB with a suitable feedback threshold achieve a better throughput performance than CS with all-beam and single-beam transmissions and the existing fair scheduling schemes.