Multicast Systems With Fair Scheduling in Non-identically Distributed Fading Channels

Multicasting is emerging as an efficient method to deliver the same data to a group of users, thereby saving network resources. The fairness between different multicast groups is an important quality-of-service (QoS) indication, but it has not been given significant attention. In this paper, we propose a normalized signal-to-noise ratio (SNR)-based fair scheduling for multiple multicast groups in multicast systems. The system fairness and capacity are then analyzed and compared for both fair scheduling and greedy scheduling over independent but non-identically distributed (i.n.d.) fading channels. Closed-form expressions in terms of the system spectral efficiency, outage probability, system fairness, and average bit error rate (BER) are derived in an uncoded/coded M-ary quadrature amplitude modulation based adaptive transmission multicast system over i.n.d. Rayleigh fading channels. Numerical results show that compared with greedy scheduling, fair scheduling achieves considerably high fairness at the cost of slight system capacity loss, regardless of the number of multicast groups. Our focus is on the physical layer without rate loss, but we also briefly discuss applications of the proposed scheduling in a cross-layer design subject to the loss rate QoS constraint.