Abstract
The 802.11ac amendment specifies that all Physical Protocol Data Units (PPDUs) are transmitted in aggregated MAC Protocol Data Units (A-MPDU) frames. Yet, when the medium is free all the eligible packets in the transmission queue are aggregated and transmitted. Hence, the size of A-MPDU aggregated frames does not depend only on the Block Acknowledgement window size but also on the number of eligible PDUs available in the transmission buffer. Even though that this specific may have a potential impact on the A-MPDU aggregation behavior, the existing analytical modelling approaches do not consider it. This may incurs inaccurate estimations of network performance. In this paper, we use markovian techniques and queuing theory to derive a mathematical model that provides accurate estimation of the A-MPDU aggregation size. An M/M/1/K queue is also considered, to reflect the impact of the network load on A-MPDU aggregation behavior. The accuracy of our model is well benchmarked by ns-3 simulator. Besides, compared to existing models, our proposal presents more precise estimation of the A-MPDU aggregation size especially in low network loads.