PASA: power adaptation for starvation avoidance to deliver wireless multimedia

In recent years, there has been an increasing interest to deliver multimedia services over wireless ad hoc networks. Due to the existence of hidden terminal and absence of central control, the medium access control protocol as used in the ad hoc networks may lead to channel capture, where some flows monopolize the channel while others suffer from starvation. As a consequence, the system throughput and fairness are greatly degraded. After showing that static power control leads to channel capture, we propose and study a distributed dynamic power control scheme termed "power adaptation for starvation avoidance" (PASA), which dynamically adjusts the transmission power of a node so as to avoid starvation. PASA is shown to be effective in breaking channel captures, hence improving short-term fairness among contending flows. It is simple, fully autonomous and requires no communication overhead. Via extensive simulations, we show that our power control algorithm achieves much better fairness without compromising system throughput through better spatial reuse. Our experiments with video sequences transmitting over different network topologies show that PASA achieves much better video quality with lower start-up delay and buffer requirement.