We employ discrete-time queueing theory to analyze the end-to-end (e2e) delay of wireless multihop networks for two MAC schemes, m-phase TDMA and slotted ALOHA. Unlike general two-dimensional networks where there exists sufficient traffic multiplexing that would permit the arrival processes to be approximated as independent, in linear networks with multihop communication, the arrival processes are correlated due to the lack of traffic multiplexing. This paper studies an extreme scenario, a linear network fed with a single flow. A decomposition approach is used to decouple the whole network into isolated nodes. Each node is modeled as a GI/Geo/1 queueing system. We derive the complete per-node delay distribution, accounting for both the queueing delay and access delay. Additionally, we characterize the departure processes by a correlated and bursty on-off traffic model. The per-node analysis provides the e2e delay mean while for the e2e delay variance, the strong correlations between the arrival processes need to be considered. Our study shows that the sign of the correlation coefficients depends on both the MAC scheme and the traffic burstiness, both of which determine the relative burst size of the source flow compared to a Bernoulli process, which constitutes an "eigentraffic" process. There is a wide gap in the e2e delay variances for the source flows with different burst sizes even if they have identical average rates. The relative burst size also determines from which direction and at which rate the departure processes converge to the eigentraffic process after traversing multiple relay nodes.
Xie and Haenggi REF investigate the end-to-end delay of a wireless multi-hop line network under both m-phase spatial TDMA and slotted ALOHA.
Towards an end-to-end delay analysis of wireless multihop networks
Ad Hoc Networks
Ad Hoc Networks
Computer Science