Enhanced uplink multi-users scheduling for future 802.11ax networks: wait-to-pick-as-available enhanced

One of the key enablers of the upcoming IEEE 802.11ax standard is the inclusion of uplink multi-users (UL MU) transmission model, which is performed using multiple-input multiple-output (MIMO) and beamforming techniques. So far, UL MU-MIMO has not been standardized in any of IEEE 802.11 amendments, because of technical issues facing its definition. One of these significant issues is the scheduling of UL MU-MIMO transmissions, which refers to selection rules and resource allocation procedures performed before simultaneous data transmissions. Indeed, simultaneous transmitters and receiver should exchange some information to correctly transmit the parallel data frames. However, this information exchange adds overheads, leading to reduce network performance. In this regard, we have proposed, in a previous work, a novel 802.11ax medium access control protocol aiming at reducing elapsed time in managing the establishment of an UL -MU communication called Wait-to-Pick-As-Available (W2PAA). Our contribution in this paper is twofold. First, we introduce an analytical model based on semi-Markov Chains to evaluate the performance of W2PAA; taking into a detailed behavior of the backoff counter (i.e. freezing period). Second, we propose an enhanced version of W2PAA aiming at improving both system and user-oriented performances. Aiming at validating the analytical model and comparing the performance of both versions of W2PAA, we used computer simulation. Obtained results, validate the analytical model in one hand, and clearly indicated the gain of both W2PAA versions by report to the basic UL-Single User on the other hand. Copyright © 2016 John Wiley & Sons, Ltd.