Performance evaluation of backoff algorithms in multi-hop wireless mesh networks

Multi-hop wireless mesh networks (M-WMNs) have recently emerged as an alternative network infrastructure. For M-WMNs to serve as a network infrastructure, the protocol designs for M-WMNs should target a high network capacity. An efficient backoff algorithm is required to achieve a high network capacity. Most of existing works focused on backoff algorithms for infrastructure environment based on IEEE 802.11 distributed coordination function (DCF) or did not consider the features of M-WMN. In this paper, we propose an adaptive backoff algorithm based on the number of contention nodes for an IEEE 802.11 DCF-based M-WMN. The proposed backoff algorithm is founded on cross-layer cooperation between the routing and the medium access control (MAC) layers. The number of contention nodes of a node is obtained from the routing layer, and then this information is used to adaptively adjust the value of the minimum contention window (CW_min) in the backoff mechanism of the MAC protocol. To evaluate the performance of the proposed backoff algorithm and existing ones, computer simulations were performed. The simulation results show that the existing algorithms do not work well in M-WMN and the proposed backoff algorithm outperforms existing ones.