An analytical model with improved accuracy of IEEE 802.11 protocol under unsaturated conditions

In this work the authors present an analytical model that - compared to previously published work- more accurately captures the delay of IEEE 802.11 protocol under low, medium, and near-saturation load conditions. A Markov chain is used to keep track of the instantaneous number of (active) nodes that have a frame to transmit. The number of active nodes varies over time and is a function of various parameters, including the frame individual maximum retransmission count. One advantage of the proposed analytical model is its ability to estimate the IEEE 802.11 protocol latency and delivery ratio in the presence of quality of service (QoS) classes, each class being defined by a specific maximum retransmission count. Such QoS classes can be adopted to support real time applications for which both latency and delivery ratio must be closely monitored for satisfactory operation. The analytical estimation of these performance parameters may offer useful feedback to admission control schemes.