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An Integrated Approach to Enhance TCP Fairness in HCCA Scheduler for 802.11e Wireless LANs

Shaik Madhar Saheb1, A. K. Bhattacharjee2, Dharmasa3, and R. Kar2
1. System Administrator, Dept. of ITSC, Caledonian College of Engineering, Oman
2. Dept. of Electronics and Communication Engineering, NIT-Durgapur, India
3. Dept. of Electronic and Computer Engineering, Caledonian College of Engineering, Oman

Abstract—IEEE 802.11e Wireless Local Area Networks (WLANs) specifies Hybrid Coordination Function (HCF) Controlled Channel Access (HCCA) technique which provides prioritized and parameterized Quality-of-Service (QoS) support in multimedia traffic. It does not, however, attain fairness in the sharing of resources with both uplink and downlink flows. There has been extensive research on the fairness at Medium Access Control (MAC) layer whereas research concerning the fairness in transport layer (TCP) is still nascent. TCP based cross-layer optimization approach for the HCCA scheduler brings forward many challenges like unfairness problem of MAC layer and path/bandwidth asymmetry of TCP. This paper proposes an integrated approach to alleviate afore mentioned problems. Firstly, a priority based weighted fairness scheme is suggested along with an adaptive buffer management technique for TCP traffic. Secondly, an acknowledgment (ACK) delaying technique is recommended which during the uplink flows delay the TCP ACK packets so that it generates more buffer space for downlink data transmission and maintains a fair flow of uplink and downlink data transmission rates. Simulation results show that this integrated approach attains and maintains fairness in both MAC and TCP upload flows with increased throughput.

Index Terms— Adaptive Buffer Size, Access Category, Access Point, Acknowledgement, Integrated approach, Transmission Opportunity, Weighted Prioritization

Cite: Shaik Madhar Saheb, A. K. Bhattacharjee, Dharmasa, and R. Kar, "An Integrated Approach to Enhance TCP Fairness in HCCA Scheduler for 802.11e Wireless LANs," Journal of Advances in Information Technology, Vol. 4, No. 1, pp. 51-57, February, 2013.doi:10.4304/jait.4.1.51-57