A tunable-fairness cross-layer scheduler for DVB-S2

Adaptability of the physical layer has become mandatory for unicast services by the second generation of the DVB-S standard, DVB-S2. This introduces new challenges as well as degrees of freedom in the design of the packet schedulers operating on the forward link. A main challenge lies in providing quality-of-service (QoS) suitable for multimedia applications meeting at the same time the required service level agreements (SLA). In this paper, we present a cross-layer approach for the design of the forward link packet scheduler that introduces fairness as a tunable parameter. This approach makes it possible to dynamically adapt the scheduler behaviour in order to guarantee fairness depending on the channel conditions. The proposed algorithm also supports differentiation of services that comply with the requirements for implementing QoS. An example scenario is proposed and system performance is computed as a function of the tunable fairness index. Our results show that tunable fairness is an effective scheduling tool for broadband satellite systems implementing adaptive physical layer. Copyright © 2006 John Wiley & Sons, Ltd.