Abstract-Wireless multicast/broadcast sessions, unlike wired networks, inherently reaches several nodes with a single transmission. For omnidirectional wireless broadcast to a node, all nodes closer will also be reached. An algorithm for constructing the minimum power tree in wireless networks was first proposed by Wieselthier Ø Ð. The ÖÓ ×Ø Ò Ö Ñ ÒØ Ð ÔÓÛ Ö (BIP) algorithm suggested by them is a "node-based" minimum-cost tree algorithm for wireless networks. We propose an alternate search based paradigm wherein minimum-cost trees in wireless networks are found through a search process. Two computationally efficient procedures for checking the feasibility (viability) of a solution in the search space are presented. A straightforward procedure for initializing the search using stochastically generated trees is also proposed.

Abstract-Broadcasting in wireless networks, unlike wired networks, inherently reaches several nodes with a single transmission. For omni-directional wireless broadcast to a node, all nodes closer will also be reached. This property can be used to compute routing trees which minimize the sum of the transmitter powers. It has been shown that this problem is NP-complete. In this paper, we present the r-shrink procedure, a heuristic for improving the solutions obtained using fast sub-optimal algorithms. Specifically, we focus on the lowcomplexity BIP algorithm and Prim's minimum spanning tree algorithm and show through extensive simulations that better solutions are obtained almost always, with considerably lower tree power, if the proposed procedure is used to improve the trees generated using these algorithms.

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Natural disasters, such as hurricanes, large wind and ice storms, typically require the repair of a large number of components in electricity distribution networks. Since power cannot be restored before the completion of repairs, optimal scheduling of available repair crews to minimize the aggregate duration of customer interruptions reduces the harm done to the affected community. While incorporating a switch on every line of a distribution network would maximize the outage management capability and resilience, cost concerns typically prohibit such an approach. In this work, we consider the fact that the number of switches is much smaller than the number of edges in the distribution network. This generalizes the problem adopted in our previous work [1]. Our modeling framework is analogous to a job scheduling problem with group soft precedence constraints on parallel identical machines to minimize the total weighted energization time. We propose a linear programming (LP) based list scheduling algorithm and a conversion algorithm and analyze their theoretical performances.

Abstract-We address several inter-related aspects of underwater network design within the context of a cross-layer approach. We first highlight the impact of key characteristics of the acoustic propagation medium on the choice of link layer parameters; in turn, the consequences of these choices on design of a suitable MAC protocol and its performance are investigated.Specifically, the paper makes contributions on the following fronts: a) Based on accepted acoustic channel models, the pointto-point (link) capacity is numerically calculated, quantifying sensitivities to factors such as the sound speed profile, power spectral density of the (colored) additive background noise and the impact of boundary (surface) conditions for the acoustic channel; b) It provides an analysis of the Micromodem-like linklayer based on FH-FSK modulation; and finally c) it undertakes performance evaluation of a simple MAC protocol based on ALOHA with Random Backoff, that is shown to be particularly suitable for small underwater networks.