Request-Based Polling Access: Investigation of Novel Wireless LAN MAC Scheme for Low-Latency E-Health Applications.

For hospital e-health systems, a novel medium access control (MAC) scheme that achieves delay-sensitive healthcare traffic (DSHT) delivery in the uplink direction of wireless local area networks (WLANs) is proposed and investigated. By introducing a slotted request uploading period and informing hubs to upload their transmission requests orderly during the period, overhead cost associated with frequent transmitter/receiver transitions can be reduced and polling empty hubs can be eliminated. Consequently, the proposed scheme results in in-time polling of hubs, thereby optimizing packet queuing delay. Moreover, due to centralized coordination, the proposed scheme avoids contention and back-off. Such an MAC scheme is critical to the Internet of Things (IoT)-based delay-sensitive healthcare applications (DSHAs), such as unmanned patient tending and tele-diagnose/surgery in future e-health systems. Our simulation results show that under a delay constraint of $200~\mu \text{s}$ , the proposed scheme outperforms both the conventional point coordination function (PCF) and distributed coordination function (DCF) schemes in terms of DSHT throughput and has a good DSHT delivery stability performance. [ABSTRACT FROM AUTHOR]