k-Strongly Connected m-Dominating and Absorbing Set in Wireless Ad Hoc Networks with Unidirectional Links

Since there is no fixed infrastructure or centralized management in wireless ad hoc networks (WANs), virtual backbone has been proposed as the routing infrastructure to alleviate the broadcasting storm problem. Because the virtual backbone nodes need to carry other node´s traffic and subject to failure, it is desirable to construct a fault tolerant virtual backbone. Most recent research has studied this problem in homogeneous networks. In this paper, we propose solutions for efficient construction of a fault-tolerant virtual backbone where the wireless nodes have different transmission ranges. Such a network can be modeled as a disk graph where any link between two nodes is either unidirectional or bidirectional. Since the graph is directed, we formulate the fault tolerant virtual backbone problem as a k- strongly connected m-dominating and absorbing set problem (k-m-SCDAS). We first propose two heuristics, one to construct a 1-m-SCDAS and the other one to obtain a k-1-SCDAS in a directed graph. We next combine these two approaches to develop a general construction of k-m-SCDAS. Through extensive simulations, we compare the performance of these proposed algorithms.