TOPOLGY CONTROL ALGORITHMS FOR WIRELESS SENSOR NETWORKS: AN OVERVIEW NEDAL ABABNEH Advanced Networks Research Group, School of Information Technologies University of Sydney, Madsen Building G4 Sydney, NSW 2006, Australia SELVAKENNEDY SELVADURAI Advanced Networks Research Group, School of Information technologies University of Sydney, G24b Madsen Building F09 Sydney, NSW 2006, Australia The main goal of a topology control scheme in wireless sensor networks is to reduce node power consumption in order to extend network lifetime. In this paper we present an overview of a range of topology control algorithms proposed in literature for wireless sensor networks. The topology control schemes in most of the existing works can be categorized into two classes: either multi-state or power-control. We believe that most energy savings might come from turning off redundant nodes rather than by minimizing node transmit power. However, both classes of schemes could be combined for further energy savings. Each algorithm is described in depth and compared against each other to capture their uniqueness. The most important design issues of topology control are also highlighted. Keywords: Wireless Sensor Networks, Topology Control Algorithms, Design Issues, Comparison. 1. Introduction Wireless sensor networks are networks of hundreds to thousands of small, low-cost, low-powered sensor nodes that are densely deployed across geographical areas. These sensor nodes have a severe limitation in their computation power, storage, radio communication capabilities, bandwidth, and have a limited irreplaceable resource of energy [Ahmed et al., 2003][Tilak et al., 2002][Akkaya & Younis, 2005][Tubaishat & Sanjay, 2003][Akyildiz et al., 2002][Vieira et al., 2003]. Thus, the most important design consideration for these networks is to extend their operational lifetime by minimising power consumption. Sensor nodes sense the environment and gather physical data, which may be processed locally and forwarded towards the data sink. Traffic forwarding through multiple hops may be needed, when the intended destination is not a direct neighbor to the given node and it can not be reached directly. Each node in the sensor network plays two roles namely, to sense and process data, and to act as a router. 1