A Traffic Control Method with Channel Occupancy Information from MAC Layer in IEEE 802.11

Wireless LAN has recently come into wide use because of its easy installation and low operating cost. Consequently, real-time applications, such as voice and video streaming, have seen increasing use in wireless environments. IEEE 802.11e was prepared as a standard for wireless LAN to improve the quality of service (QoS) for real-time applications; however, it cannot offer the required QoS when there is excessive traffic. This is because the controls in IEEE 802.11e only schedule traffic in the MAC layer for the generated traffic in the upper layer, and do not control the volume of traffic generation itself. To solve this problem, we propose an autonomous method to control traffic generation in the application layer by using wireless channel occupancy information in the MAC layer. In the proposed method, the wireless channel occupancy is estimated from the network allocation vector (NAV) in the CSMA/CA control, and then traffic generation is managed adequately with cross-layer controls. We implemented and evaluated the proposed method in a testbed, demonstrating that the QoS is improved against the conventional IEEE 802.11 control.