Utility-based Packet Scheduler for Wireless Communications

Following widespread availability of wireless Internet, a wide range of applications with differing QoS requirements must share the wireless access. The objective of this work is to provide QoS support to different applications delivered over a wireless link shared by different users. We propose a link-layer packet scheduler following the cross layer concept: the channel-aware scheduling approach is extended by information about the importance of individual packets for the application. For this purpose we use utility curves, which map network service delivered to a given data flow to application-perceived quality. We define a single scheduling metric which expresses, for each packet, the balance between the quality increase of the flow served and the quality loss of the flows that are not. We evaluated our concept through extensive simulations with mixes of VoIP and file download flows. The results show that our maxsum utility-based scheduler clearly improves the quality seen by the VoIP flows when compared to a channel-aware round robin (caRR)/proportional fair scheduler (PFS), respectively. Further, this is achieved while delivering similar amount of data to file download users. We also show how different forms of the utility curves can be used to achieve differentiated QoS provisioning to users/applications with different priorities/ requirements