DPQ: Using A Distributed Priority Queue to Improve Ad hoc TCP Performance

Network traffic can be broken into two categories: control packets (such as routing exploration/reply packets) and payload data packets. In a wireless ad hoc environment, it is generally accepted that control packets should be given higher priority for scheduling. In practice, it is also implemented this way within a single node. However, packets scheduling is not handled similarly from a distributed perspective. Control packets in one mobile node and data packets in another mobile node equally compete for the shared channel for future packet delivery. It is pointed out that under this policy, aggressiveness of TCP will hurt the successful delivery of control packets, which in turn will adversely impact TCP performance. In this paper, we propose and evaluate a partially ordered, distributed priority queue scheduling for the mobile ad hoc environment. Its performance is evaluated using network simulator ns2. The simulation results show that our mechanism can dramatically improve TCP performance by up to 20% in the ad hoc environment