Joint rate and fragment size adaptation in IEEE 802.11n wireless LANs

For high-speed 802.11n WLANs, we propose a joint rate and fragment size adaptation scheme incorporated into the aggregation scheme, AFR (Aggregation with Fragment Retransmission), in which multiple packets are f rstly fragmented and then aggregated into in a single large frame. We investigate how to control the frame and fragment size as well as the transmission rate in dynamic channel condition. In the proposed scheme, the transmitter estimates the fragment error probability in the MAC layer, which can characterize channel quality, and uses simple look-up table of thresholds which are obtained from the perfow throughput equation for various PHY modes and fragment sizes. Through extensive simulations, we show that the proposed scheme has comparable throughput performance with the ideal performance which is obtained under the assumption that perfect channel information can be available at the transmitter as well as has higher throughput than the existing open-loop rate adaptation scheme.