Impact of queuing discipline on packet delivery latency in ad hoc networks

Delivering live multimedia streaming over ad hoc networks can improve coordination in battlefields, assist in disaster recovery operations, and help prevent vehicular traffic accidents. However, ad hoc networks often experience congestion faster than wired networks, leading to high end-to-end delays and jitter even for moderate traffic. This paper describes a partial remedy that applies to delay sensitive but loss tolerant applications such as live streaming. We find that under relatively high UDP traffic load, the Last-In-First-Out (LIFO) with Frontdrop queuing discipline achieves less than half the delay of the commonly used First-In-First-Out (FIFO) with Taildrop, while maintaining similar jitter. In low traffic situations, FIFO and LIFO have similar delays, but FIFO with Frontdrop has the lowest jitter. The results can be applied to an adaptive queuing mechanism that changes the queuing discipline at nodes function of the locally observed traffic load. The advantage of such an approach is that it does not require new protocols and does not incur any network overhead.