Havana: Supporting Application and Channel Dependent QoS in Wireless Packet Networks

For wireless channels, interference mitigation techniques are typically applied at the packet transmission level. In this paper, we present the Havana framework which supports integrated adaptive-QoS in wireless packet networks by responding to impairments over multiple time scales that are present at the flow/session level. The Havana framework is based on three different control mechanisms that operate over distinct adaptation time scales. At the packet transmission time scale, a packet-based channel predictor determines whether to transmit a packet or not depending on the state of the wireless channel. At the packet scheduling time scale, a compensator credits and compensates flows that experience bad link quality. Over even longer time scales an adaptor regulates flows taking into account the ability of wireless applications to adapt to changes in the available bandwidth and channel conditions. We present the design and implementation of our framework and evaluate each of the proposed control mechanisms using the ns-2 simulator.