Self-Organizing TDMA MAC Protocol for Effective Capacity Improvement in IEEE 802.11 WLANs

This paper presents a MAC protocol named self- organizing time division multiple-access (SO-TDMA) aiming to enable quality-of-service (QoS) provisioning for delay-sensitive applications. Channel access operation in SO-TDMA is similar to carrier-sense multiple-access (CSMA) in the beginning, but quickly converges to TDMA with an adaptive pseudo-frame structure. This approach has the benefits of TDMA in a high-load traffic environment, while overcoming its disadvantages in low-load, heterogeneous traffic scenarios. Furthermore, it supports distributed and asynchronous channel-access operation as in CSMA. These are achieved by dynamically adapting the transmission opportunity duration based on the common idle/busy channel state information acquired by each node through learning, without explicit message passing. Performance comparison of CSMA, TDMA, and SO-TDMA in terms of effective capacity, system throughput, and collision probability is investigated.