Packet management scheme for location-independent end-to-end delay in IEEE 802.11s multi-hop wireless mesh networks

We consider IEEE 802.11s multi-hop wireless mesh network under multi-channel and multi-radio environments. We decompose the mesh network into disjoint zones by using multiple channels and multiple radios such a way that i)mesh nodes in a zone are within one-hop distance and compete with other nodes to access the channel using IEEE 802.11e EDCA, ii) neighbor zones use different channels, iii) each node can send and receive the packets simultaneously. Thus we may focus on a single zone in order to derive the performance measure such as end-to-end delay. We propose packet management scheme at relay node where relay packets passing by more hops are buffered in higher priority AC of EDCA. Firstly, we model one zone as one-hop 802.11e EDCA network and find the HoL-delay of packet of each AC at relay node in a zone. Secondly, by modeling each AC as M=G=1 queue with HoL-delay as service time, we obtain packet delay (sum of queueing delay and HoL-delay) in a zone. The average end-to-end delay is calculated by summing up of packet delays in zones along the designated route. The goal of the packet management scheme in this paper is to provide location-independent end-to-end packet delays in the sense that all end-to-end packet delays regardless of nodes’ location are almost same. To do this, we propose a method to determine the minimum contention window size of ACs so as to have shorter delay for AC with relay packets passing by more hops. Finally, we suggest a heuristic algorithm to reduce the difference of delays due to packets’ originated location and eventually to achieve the fair end-to-end delay of packets regardless of nodes’ location. Numerical results show that our proposed algorithm guarantees the location-independent end-to-end delay of packets in all the zones, regardless of locations.