Distributed TXOP Allocation Scheme in IEEE 802.11e Wireless LANs

Abstract

Multimedia traffic is expected to be one of the most important traffic types in wireless LANs. However, multimedia traffic is very sensitive to delay so that the traffic has to be transmitted to receivers within its delay bound. The IEEE 802.11e EDCA (Enhanced Distributed Channel Access) defines a TXOP (Transmission Opportunity) parameter to provide service differentiation and QoS (Quality of Service) of the traffic. A station can continuously transmit multiple packets for the duration of a TXOP. When stations support multimedia applications with different QoS requirements, fairness problem occurs. In order to alleviate the fairness problem, we propose a distributed TXOP allocation scheme based on the delay bound. In the proposed scheme, a station checks the delay bound of each data packet in the queue, and allocates its TXOP value to guarantee the delay bounds of all the packets in the queue. Simulation results show that the proposed scheme outperforms other TXOP allocation schemes.