Resource Management for OFDMA based Next Generation 802.11ax WLANs

摘要

Recently, IEEE 802.11ax Task Group has adapted OFDMA as a new technique forenabling multi-user transmission. It has been also decided that the schedulingduration should be same for all the users in a multi-user OFDMA so that thetransmission of the users should end at the same time. In order to realize thatcondition, the users with insufficient data should transmit null data (i.e.padding) to fill the duration. While this scheme offers strong features such asresilience to Overlapping Basic Service Set (OBSS) interference and ease ofsynchronization, it also poses major side issues of degraded throughputperformance and waste of devices' energy. In this work, for OFDMA based 802.11WLANs we first propose practical algorithm in which the scheduling duration isfixed and does not change from time to time. In the second algorithm thescheduling duration is dynamically determined in a resource allocationframework by taking into account the padding overhead, airtime fairness andenergy consumption of the users. We analytically investigate our resourceallocation problems through Lyapunov optimization techniques and show that ouralgorithms are arbitrarily close to the optimal performance at the price ofreduced convergence rate. We also calculate the overhead of our algorithms in arealistic set-up and propose solutions for the implementation issues.