Practical Realisation and Validation of aWi-Fi Policing Algorithm

Node misbehavior has attracted much research interest. However, much of the focus of prior research is on detection of node misbehavior, and little work has been done on counteracting that misbehavior. Those who do address this issue lack robustness, flexibility, or feasibility for implementation on real hardware. As the IEEE 802.11 standard’s medium access mechanism is decentralized, stations can potentially refuse to abide by the standard and gain performance benefit at the cost of the performance of compliant stations. In this thesis, we study, extend, and implement a policing algorithm that has been previously introduced for IEEE 802.11 b/g networks, and make it practically feasible for implementation on real hardware. We provide proof that the extended algorithm is robust and can effectively address the problem of policing IEEE 802.11 node misbehavior by eliminating the performance advantage for noncompliant stations. We outline the domain of scenarios this algorithm can be adapted to, and those it is not designed for. To prove the effectiveness of the scheme in a real network, we implement it on real wireless adapters using the OpenFWWF firmware, conduct a wide range of experiments for different network scenarios. We provide results that confirm the extended algorithm’s correct functionality for cases it is designed to support. We also consider the results in light of newer features of IEEE 802.11 standard. We conclude that the extended policing algorithm can in fact force stations to comply with the IEEE 802.11 standard (although some new IEEE 802.11 features may impair its functionality) and its application does not result in network degradation, and it is effective even under undesirable network conditions.

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