Graduate School and Research Center In communication systems

Seminar: TXOP Exchange: A Mechanism for Cooperation in CSMA Networks

Ryoichi Shinkuma - Assistant Professor, Kyoto University

Communication systems

Date: March 28, 2011

Location: Eurecom - Salle EN05

Conventional mechanisms proposed for enhancing quality of service (QoS) in 802.11 networks suffer from the lack of backward compatibility with legacy devices as well as the lack of fairness to legacy devices. This talk presents a cooperative mechanism called TXOP (transmission opportunity) Exchange, that provides a legacy-neutral solution in which only stations (STAs) participating in TXOP Exchange cooperatively use their available bandwidth to satisfy their required throughputs, while other legacy devices continue to see same throughput performance as before. Specifically, we discuss the architecture for TXOP Exchange using a logical coordination server (implemented in software), its implementation in legacy 802.11 networks and algorithms for fair and efficient MAC cooperation using the Nash bargaining solution (NBS). We show that this mechanism can be realized with minor modifications to the RTS (request-to-send) frames of only the STAs participating in TXOP Exchange but without any replacement of legacy APs and STAs. Further, the proportional fair NBS-based algorithm also ensures fair incentives for cooperation between STAs for various throughput requirements of users and in various channel conditions. The simulation study using a realistic simulator verifies that the TXOP Exchange mechanism ensures legacy neutrality and fair and efficient cooperation even when a large number of legacy STAs coexist.

TXOP Exchange: A Mechanism for Cooperation in CSMA Networks