A channel adaptive hybrid aggregation scheme for next generation wireless LAN

Abstract

Hybrid aggregation is a frame aggregation scheme in IEEE 802.11 Medium Access Control (MAC) which combines the use of MAC Service Data Unit Aggregation (A-MSDU) and MAC Protocol Data Unit Aggregation (A-MPDU) together. Using hybrid aggregation, we can get higher throughput than using either A-MSDU or A-MPDU only scheme. However, the throughput may decrease in some high Bit Error Rate (BER) conditions depending on the length of each A-MSDU frames in the hybrid aggregated frame. An A-MSDU frame has only one Frame Check Sequence (FCS) because A-MSDU is treated as one MSDU. Therefore, even if only one MSDU in an A-MSDU frame has bit errors, whole frame retransmission is needed. This is the disadvantage of A-MSDU aggregation scheme which affects the throughput of hybrid aggregation. To reduce this A-MSDU influence on hybrid aggregation, in this paper, we propose a novel channel adaptive aggregation scheme. By controlling the number of the MSDUs for A-MSDU aggregation, we can adapt the hybrid aggregation scheme to the channel condition. Using computer simulations, we show that the proposed hybrid aggregation scheme can reduce the frame error probability and improve the throughput more efficiently than conventional one.