Receiving opportunity control used admission control scheme for wireless multi-hop networks

The purpose of this study is to guarantee Quality of Service (QoS) in wireless multi-hop networks by introducing an admission control scheme. In wireless single-hop networks, IEEE 802.11e Enhanced Distributed Channel Access (EDCA) is the standard for QoS control. However, to control QoS, it is necessary to modify the currently used IEEE 802.11 Distributed Coordination Function (DCF)-compliant terminals and to improve the throughput performance of IEEE 802.11e EDCA, which significantly deteriorates in heavy traffic. The authors previously proposed a per-flow QoS control scheme, called Receiving Opportunity Control in MAC Frame (ROC), in which the Access Point (AP) intentionally does not return ACKs for low-priority data frames. Using ROC and IEEE 802.11 DCF mechanisms, the back-off timer of low-priority flows increases and higher transmission opportunities are provided for high-priority flows. Although ROC causes slight performance degradation in total throughput, it is not necessary to modify existing terminals and ROC provides flexible and more fine-tuned QoS control in heavy loads compared to IEEE 802.11e EDCA. This paper proposes a novel scheme to guarantee the QoS of high-priority flows in wireless multi-hop networks with ROC-employed per-flow admission control. In the proposed scheme, the edge APs that connect terminals apply ROC to low-priority flows according to the buffer occupancy rate at the network nodes, and the admission control suppresses the inflow of low-priority frames to core networks. As a result, QoS of high-priority flows is guaranteed without modifying existing terminals. Simulation results show that the proposed scheme can achieve QoS, as required, in comparison to conventional schemes.