A Game-Theoretic Framework for Medium Access Control

In this paper, we generalize the random access game model, and show that it provides a general game-theoretic framework for designing contention based medium access control. We extend the random access game model to the network with multiple contention measure signals, study the design of random access games, and analyze different distributed algorithms achieving their equilibria. As examples, a series of utility functions is proposed for games achieving the maximum throughput in a network of homogeneous nodes. In a network with n traffic classes, an N-signal game model is proposed which achieves the maximum throughput under the fairness constraint among different traffic classes. In addition, the convergence of different dynamic algorithms such as best response, gradient play and Jacobi play under propagation delay and estimation error is established. Simulation results show that game model based protocols can achieve superior performance over the standard IEEE 802.11 DCF, and comparable performance as existing protocols with the best performance in literature

A Novel Approach to Contention Control in IEEE 802.11e-Operated WLANs

In this paper, we devise, in compliance with the IEEE 802.11e protocol [1], a novel MAC-centric approach, called MAC contention control (MCC), to maximizing the bandwidth utilization and achieving proportional bandwidth allocation. We first show that approaches based on estimating the number of competing nodes and then setting the contention window size may not converge (and in some cases diverge) because of network dynamics. Then, by studying the optimality condition derived in our prior work [10], we identify two parameters (referred to as control references) that remain approximately constant when the network operates at the optimal operational point, regardless of the number of competing nodes in each AC. We instrument MCC to measure these control references, compare measurement results to their optimal control reference levels, and adjust the packet dequeuing rate from the interface queues in an additive-increase-multiplicative-decrease (AIMD) fashion and with respect to pre-specified bandwidth allocation ratio associated with its AC. In some sense, MCC controls the rate of passing packets from the interface queues to the MAC access function, and thus practically controls the effective number of competing nodes. We have conducted an extensive simulation study, and demonstrated the superiority of MCC to 802.11e in terms of both the achievable network throughput and the capability of achieving proportional bandwidth allocation. This, coupled with the fact that MCC does not require change in firmware and can be practically deployed, makes MCC a viable approach to contention control in IEEE 802.11e-operated WLANs

Game theoretic approach to medium access control in wireless networks

Wireless networking is fast becoming the primary method for people to connect to the Internet and with each other. The available wireless spectrum is increasingly congested, with users demanding higher performance and reliability from their wireless connections. This thesis proposes a game-theoretic random access model, compliant with the IEEE 802.11 standard, which can be integrated into the distributed coordination function (DCF). The objective is to design a game theoretic model that potentially optimizes throughput and fairness in each node independently and, therefore, minimise channel access delay. This dissertation presents a game-theoretic MAC layer implementation for single-cell networks and centralised DCF in the presence of hidden terminals to show how game theory can be applied to improve wireless performance. A utility function is proposed, such that it can decouple the protocol's dynamic adaptation to channel load from collision detection. It is demonstrated that the proposed model can reach a Nash equilibrium that results in a relatively stable contention window, provided that a node adapts its behaviour to the idle rate of the broadcast channel, coupled with observation of its own transmission activity. This dissertation shows that the proposed game-theoretic model is capable of achieving much higher throughput than the standard IEEE 802.11 DCF with better short-time fairness and significant improvements in the channel access delay