Enhancing Network Throughput via the Equal Interval Frame Aggregation Scheme for IEEE 802.11ax WLANs

Frame aggregation is fully supported in the newly published IEEE 802.11ax standard to improve throughput. With frame aggregation, a mobile station combines multiple subframes into an aggregate MAC service data unit (A-MSDU) or an aggregate MAC protocol data unit (A-MPDU) for transmission. It is challenging for a mobile station in 802.11ax WLANs to set an appropriate number of subframes being included in an A-MSDU or A-MPDU. This problem is solved in this paper by the proposed equal interval frame aggregation (EIFA) scheme which lets a mobile station aggregate at most k subframes at a fixed time period of T. A novel Markov model is developed for deriving the probability of number of subframes in the data buffer at the mobile station, resulting in the throughput and packet delay in the EIFA. Moreover, the optimization problem of maximizing the throughput with the constraint on delay is formulated, and its solution leads to the optimal pair of parameters k and T for improving throughput in the EIFA scheme. Simulation results show the EIFA has a higher throughput than the ones in which the mobile station chooses the minimum, the maximum, or a random number of subframes.