Multi-rated packet transmission scheme for IEEE 802.11 WLAN networks

In a multirate wireless network such as IEEE 802.11 WLAN, the connection having a good channel condition uses a high transmission rate and the connection having a poor channel condition uses a low transmission rate. However, this coexistence of different transmission rates degrades the total system performance of the network. In order to eliminate this performance abnormality and improve protocol capacity, we propose a new packet transmission algorithm, the RAT (Rate-Adapted Transmission) scheme. The RAT scheme distributes the wireless channel fairly based on the channel occupancy time. Moreover, it efficiently transmits packets even in a single station using rate-based queue management. Therefore, the RAT scheme obtains not only the inter-rate contention gain among stations but also the intra-rate contention gain among connections in a single station. By simulation, we show that the proposed RAT scheme is superior to the default IEEE 802.11 MAC DCF access method and the modified OAR (Opportunistic Auto Rate) scheme.