Vinay Kolar
ABSTRACT
In multi-hop wireless networks with Carrier Sense Multiple Access (CSMA), unfairness may arise due to a number of reasons. A majority of the existing work focuses on fairness issues due to hidden terminals and the impact on backoff mechanisms. This paper focuses on the unfairness arising due to unequal contention opportunities at a node; some nodes rarely observe an idle channel since two or more interferers that are not in range with each other can transmit together. Contention unfairness is unrelated to hidden terminals. In order to understand the impact of contention and gain insight into developing solutions for contention unfairness, we develop a model from first principles for contention in IEEE 802.11 networks. The accuracy of the model is validated through simulations and the results show that such unfairness is a common phenomenon. Based on the insights gained from the model, we propose and evaluate a distributed scheme that reduces the effect of unfairness due to contention. Simulation results show that the proposed scheme achieves an average improvement of 25% in fairness, with a small reduction in overall throughput.
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Index Terms
- Contention in multi-hop wireless networks: model and fairness analysis
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