Hybrid Coordination Function Controlled Channel Access for Latency-Sensitive Tactile Applications.

The Internet has evolved a long way from transporting basic web data to transporting traffic instigated by new emerging applications that are available today. One such application is remote human-to-machine interaction, in which touch and actuation related information is delivered over the network. These applications are extremely sensitive to latency, with some reporting latency requirements in the millisecond range. Therefore, it is crucial to minimize latency experienced in each and every segment of the network. In this paper, we consider a scenario in which tactile body-worn devices are connected using the IEEE 802.11 network, and analyze the wireless transmission latency from these devices to the wireless access point, when the hybrid coordination function controlled channel access (HCCA) MAC protocol is used. In particular, we use queuing theory based approach to derive closed-form expressions for the average latency. We use the insights gained from our latency analysis to propose a new service interval selection method that outperforms the HCCA reference design. We show for the first time the parameters that have significant impact on latency and how these can be manipulated to meet the stringent latency constraints.