Link-adaptable polling-based MAC protocol for wireless LANs

The IEEE 802.11 standard defines a centralized polling-based channel access method, the point coordination function (PCF), to support time-bounded services. In this paper, we propose an efficient polling scheme, referred to as two-step multipolling (TS-MP), for the PCF in WLANs. In this new scheme, we propose to use two multi-polling frames for different purposes. The first frame is broadcasted to collect information such as the numbers of pending frames and the physical layer transmission rates for the communication links among all stations. The second frame is broadcasted with a polling sequence for data transmissions designed by utilizing the collected information. Extensive simulation studies show that TS-MP not only overcomes PCFs deficiencies, but also helps to implement rate adaptation over a time-varying wireless channel.