DAPP: A Delay-Aware Packet Prioritisation scheme for VoIP in wireless multi-hop networks

In this paper we propose a mechanism entitled Delay-Aware Packet Prioritisation (DAPP) that works at WiFi packet queue level. DAPP enqueues packets according to their time spent in the network, such that more delayed packets are enqueued towards the head of the queue. We study the effects of such an approach in wireless multi-hop scenarios where VoIP packets with various delay impairments reach a congested node. Packets' delay builds up as congestion increases and we show that DAPP improves a network's VoIP capacity by distributing the negative effects of delay to those VoIP packets that so far travelled in good network conditions. This is to the advantage of those VoIP packets already negatively affected by network conditions, as they are allowed to pass a congested node with less further delay accumulation. We use extensive NS-3 simulations where a wide range of network impairments affect VoIP calls, and we demonstrate that DAPP is able to improve the VoIP capacity and fairness among VoIP calls in a wireless multi-hop network.