Voice over IP applications require a playout buffer at the receiver side to smooth network delay variations. Unfortunately, existing algorithms for dynamic playout adjustment designed for wireline networks do not operate correctly in wireless ad hoc networks. These algorithms estimate the end-to-end delay on the set of previous received audio packets. Indeed, such a delay estimation based on past history is not appropriate due to mobility which leads to random changes of the network topology. In this paper, we highlight this delay estimation problem. We show that route request AODV control messages provide more accurate delay estimation. Then, we propose a new algorithm for playout delay adjustment based on these control messages. The performance evaluation is performed by simulation using ns-2. We show that this algorithm outperforms existing playout delay adjustment algorithms. Performance criteria are loss late percentage (reliability criterion), averaged playout delay (interactivity criterion) and playout delay variation (stability criterion).

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Efficient message dissemination in ad hoc networks can be fostered by exploiting stable (sub-)structures. By efficient we mean low network resource usage regarding reachability. In this paper we build a hierarchical protocol. We first create single-hop clusters among stableconnected devices. On top of those clusters, we further determine intercluster relays (ICR), finally providing an overall stable-connected structure. Our proposed stable linked structure flooding (SLSF) protocol efficiently disseminates data among stable nodes. Additional fault recovery mechanisms are employed to compensate for local intermittent node failures if needed. The experiments show that our approach increases flooding performances with a low bandwidth usage. Furthermore SLSF remains very efficient with or without the fault recovery mechanism that provides robustness.