Abstract. While many existing rate adaptation schemes in IEEE 802.11 Wireless LANs result in severe throughput degradation since they do not consider the collision effect when selecting the transmission rate, CARA (Collision-Aware Rate Adaptation) [1] shows improved system performance thanks to its collision-awareness capability. In this paper, we propose two enhancements to the original CARA scheme to further improve the system performance. The first one is called CARA-RI, which extends CARA's collision-awareness capability in making rate increase decisions, while the second one, called CARA-HD, incorporates a hidden station detection mechanism. Simulation results show that the proposed schemes outperform the original CARA significantly under various randomly-generated network topologies.
We develop a new wireless link quality metric, ECOT (Estimated Channel Occupancy Time) that enables a high throughput route setup in wireless mesh networks. The key feature of ECOT is being applicable to diverse mesh network environments where IEEE 802.11 MAC (Medium Access Control) variants are used. We take into account the detailed operational features of various 802.11 MAC protocols, such as 802.11 DCF (Distributed Coordination Function), 802.11e EDCA (Enhanced Distributed Channel Access) with BACK (Block Acknowledgment), and 802.11n A-MPDU (Aggregate MAC Protocol Data Unit), and derive an integrated link metric that enables finding maximum throughput end-to-end routes. Through simulations in randomized topological environments, we evaluate the performance of the proposed link metric and routing strategy to demonstrate that our proposed schemes can achieve up to 354.4% throughput gain over existing ones.
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