Self Organization and Self Maintenance of Mobile Ad Hoc Networks through Dynamic Topology Control

One way in which wireless nodes can organize themselves into anad hoc network is to execute a topology control protocol, which is designed to build a network satisfying specific properties. A number of basic topology control protocols exist and have been extensively analyzed. Unfortunately, most of these protocols are designed primarily for static networks and the protocol designerssimply advise that the protocols should be repeated periodically to deal with failures, mobility, and other sources of dynamism. However, continuously maintaining a network topology with basic connectivity properties is a fundamental requirement for overall network dependability. Current approaches consider failures only as an afterthought or take a static fault tolerance approach, which results in extremely high energy usage and low hroughput. In addition, most of the existing topology control protocols assume that transmission poweris a continuous variable and, therefore, nodes can choose an arbitrary power value between some minimum and maximum powers. However, wireless network interfaces with dynamic transmission power control permit the power to be set to oneof a discrete number of possible values. This simple restriction complicates the design of the topology control protocol substantially. In this paper, we present a set of topology control protocols, which work with discrete power levels and forwhich we specify a version that deals specifically with dynamic networks that experience failures, mobility, and other dynamic conditions. Our protocols are also novel in the sense that they are the first to consider explicit coordination betweenneighboring nodes, which results in more efficient power settings. In this paper, we present the design of these topology control protocols, and we report on extensive simulations to evaluate them and compare their performance against existing protocols. The results demonstrate that our protocols produce very similartopologies as the best protocols that assume power is a continuous variable, while having very low communication cost and seamlessly handling failures and mobility.