Admission control and scheduling for QoS guarantees for variable-bit-rate applications on wireless channels

Abstract

Providing differentiated Quality of Service (QoS) over unreliable wireless channels is an important challenge for supporting several future applications. We analyze a model that has been proposed to describe the QoS requirements by four criteria: traffic pattern, channel reliability, delay bound, and throughput bound. We study this mathematical model and extend it to handle variable bit rate applications. We then obtain a sharp characterization of schedulability vis-a-vis latencies and timely throughput. Our results extend the results so that they are general enough to be applied on a wide range of wireless applications, including MPEG Variable-BitRate (VBR) video streaming, VoIP with differentiated quality, and wireless sensor networks (WSN).Two major issues concerning QoS over wireless are admission control and scheduling. Based on the model incorporating the QoS criteria, we analytically derive a necessary and sufficient condition for a set of variable bit-rate clients to be feasible. Admission control is reduced to evaluating the necessary and sufficient condition. We further analyze two scheduling policies that have been proposed, and show that they are both optimal in the sense that they can fulfill every set of clients that is feasible by some scheduling algorithms. The policies are easily implemented on the IEEE 802.11 standard. Simulation results under various settings support the theoretical study.

Adaptive Flow Control for Enabling Quality of Service in Tactical Ad Hoc Wireless Networks

“…One approach uses a combination of admission control and scheduling to make resources available to applications on networks in which links are characterized by a probability of dropping a packet [Hou 2009a, Hou 2009b. These researchers provide an admission test based on long-term average throughput.…”

Optimal scheduling of real-time traffic in wireless networks with delayed feedback

“…In other related works, researchers have studied wireless single-hop networks [5], [6], [7], [8], [9]. The authors in [5] proposed an analytical framework to model a network supporting unicast traffic with deadlines and instant feedback.…”

“…Based on this framework, two debt-based policies that meet any feasible constraints were presented. Articles [6], [7], [8], [9] extend the model in [5] to a variety of scenarios: [6] considers variable-bit-rate traffic; [7] generalizes for heterogeneous deadlines and time-varying channel; [8] models multicast traffic with instant feedback; and [9] models broadcast traffic with no feedback.…”

Packet Scheduling in Wireless Networks with Unreliable Links

“…However, the unstable wireless links are not considered. In paper [5,6,7,8,9,10], the unstable wireless links are considered. In these studies, each user has the real-time throughput requirement which means the number of packets arrive at the destination nodes within a specific deadline should be greater than some bounds.…”