Broadcast is a fundamental operation in networks, especially in reconfigurable wireless ad hoc networks. For example, some form of broadcasting is used by all on-demand mobile networks routing protocols, when there is uncertainty as to the location of the destination node, or for service discovery. In this work, we present a new approach to efficient broadcast in networks with dynamic topologies, and we introduce the time sequence scheme (TSS), a new online local broadcasting algorithm for such networking environments. TSS ranks by priority, in a distributed way, candidate broadcasting nodes so that the overall number of re-broadcasts in the network is minimized. We evaluate TSS, showing that its performance comes remarkably close to the corresponding theoretical performance bounds, even in the presence of packet loss due, for example, to MAC-layer collisions. Furthermore, we compare our algorithm with a number of recently proposed schemes considering their performance in various realistic network mobility scenarios. We demonstrate that TSS performance is robust in the context of mobility induced topology reconfigurations-including temporal network partitioning-during propagation of the broadcast message.
Application-aware routing exploits static knowledge of an applica tion's traffic pattern to improve performance compared to general purpose routing algorithms. Unfortunately, traditional approaches to application-aware routing cannot efficiently handle dynamic changes in the traffic pattern limiting its usefulness in practice. In this paper, we study application-aware routing under traffic uncer tainty. Our problem formulation allows an application to statically specify an uncertainty set of traffic patterns that each occur with a given probability, and our goal is to find a single set of combined routes that will enable high-performance across all of these traffic patterns. We show how efficient combined routes can be found for this problem using convex optimization. These combined routes are optimal when the performance for every traffic pattern using the combined routes is the same as the performance using routes that are specialized for just that traffic pattern. We derive necessary and sufficient conditions for when our optimization framework will find optimal combined routes. We use theoretical and numerical analysis for the important class of permutation traffic patterns to quantify how often optimal combined routes exist and to determine the performance loss when optimal combined routes are infeasi ble. Finally, we use a cycle-level simulator that includes realistic pipeline latencies, arbitration, and buffered flow-control to study the latency and throughput of combined routes compared to spe cialized routes and routes generated using general-purpose routing algorithms. The theoretical analysis, numerical analysis, and simu lation results in this paper provide a first step towards more flexible application-aware routing.
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