The Impact of Transmission Opportunity (TXOP) on the Performance of Priority based Contention based Scheduling Strategies in Multi-hop Mesh Networks

Wireless Mesh Networks (WMNs) face multiple problems. An increase in the number of hops for packets to reach the destination results in an increase in contention for the medium which also results in an increase in the collision rates. The enhanced distributed channel access (EDCA) mechanism was developed to provide differentiated services to data with different priority levels in the IEEE 802.11e standard. The EDCA is a distributed, contention-based channel access mechanism of the hybrid coordination function (HCF) which results in an unfairness problem where higher priority data can starve lower priority data. We adopt the EDCA architecture for heterogeneous data in telemetry and IoT applications to address these problems of EDCA in multi-hop mesh networks. An adaptive weighted round robin (AWRR) scheduling strategy has been proposed and tested on multi-hop networks in our previous work. With the AWRR strategy, although packet loss is reduced, the end-to-end delay increases with high and medium priority data compared to EDCA in WMNs. In this paper we investigate the effect of the Transmission Opportunity (TXOP) bursting on the global performance in a WMN through setting up simulations in OMNeT++ using the INETMANET framework. Simulation results have shown that using TXOP-bursting in the priority based scheduling which follows the concept of schedule before backup helps reduce packet loss as well as reduce the end-to-end delay. TXOP further optimizes the performance of AWRR.