Semi-synchronous Multiple Transmission Control / Collision Inference Exploiting Capture Effect for Collision and against Collision

This paper proposes a novel MAC, SMTC/CI (semi-synchronous multiple transmission control / collision inference), for densely deployed IEEE 802.11 wireless LANs. SMTC/CI aims to achieve high throughput while maintaining throughput-fairness among stations by exploiting the capture effect and synchronizing the transmission opportunities between wireless LANs on autonomous distributed control. With high throughput, there is a dilemma in which it is important to both asynchronously send frames from inside stations to prevent collisions and synchronously send frames between wireless LANs to obtain the capture effect. The proposed SMTC/CI solves the dilemma and achieves both. In addition to high throughput, the throughput-fairness between stations can be maintained because the SMTC/CI treats all stations of the OBSS fairly. SMTC/CI changes the CW control of each terminal so that some stations synchronously send information to each other and other stations asynchronously send information to each other. SMTC/CI decides the CW change based only on the local information, which includes the history of successful transmissions and failed transmissions. The simulation results show that throughput is improved up to 115% compared with conventional MAC while retaining sufficient high throughput-fairness.