A. Mahimkar (USA) and R.K. Shyamasundar (India)
Wireless Sensor Networks, Topology Control, Code Assignment, Graph Theory, List Coloring
In this paper, we aim to solve hidden terminal problem in sensor networks. We approach the solution in two lev els. First, we develop a topology control algorithm, where each node makes local decisions to construct its set of rel ative neighbors to which it can communicate directly. Us ing transitivity and relative neighborhood, the algorithm re duces the number of direct communication links as well as reduces interference. We analytically prove that the topol ogy derived using the algorithm preserves network connec tivity. Our approach achieves an upper bound of six on the node degree and is thus better than the Cone-based [4] and Wattenhofer et al. approach [8]. Further, we develop a dis tributed code assignment algorithm where the sensor nodes use orthogonal CDMA codes for communication. The code assignment is done by viewing the problem as a list color ing problem. The algorithm assigns codes in such a way that it eliminates direct and hidden terminal interference. We show that using our algorithm, seven CDMA codes are sufficient for communication in a sensor network to elim inate both primary and hidden terminal interference. The comparative evaluation of our algorithm with LEACH [5], depicts that our algorithm is superior in terms of packet throughput, network lifetime and energy savings.
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