Poster Abstract: Throughput-Delay Tradeoff in Small and Sparse Mobile Ad hoc Networks

The asymptotic throughput-delay tradeoff has been extensively studied for dense wireless mobile ad hoc networks (MANETs) as a function of increasing density. However, many practical applications exist for sparse MANETs where mobile node density goes to zero and the number of nodes is small. Asymptotic throughput-delay laws discovered for dense networks need not identically hold in this sparse regime. This paper takes the first step in characterizing the throughput-delay tradeoff for such sparse MANETs. We find that as the MANET becomes sparser, throughput decreases and delay increases, as expected. If relaying is disabled then the throughput and delay depend only on the size of the area of operation. While relaying does increase throughput, the single packet relaying strategy worsens the delay for small MANETs. Greedy relaying overcomes this worsening without trading throughput, but only for rapidly mixing mobility. Unlike in dense networks, local broadcasting does not provide any significant benefit. Packet repetition does decrease delay, but only at the expense of reduced throughput, for small MANETs. For slowly mixing mobility, relaying worsens delay for small sparse MANETs and none of the above techniques help. Our results are useful in practical underwater MANETs where n is typically small and the MANET is sparse.