Unified Approach for Topology Control in IEEE 802.15.4 –based WSN Petia TODOROVA 1 , Radosveta SOKULLU 2 1 FRAUNHOFER FOKUS , Kaiserin-Augusta-Alee 31, 10589 Berlin, Germany Tel: + 493034637251, Fax: +493034638000, Email: petia.todoroval@fokus.fraunhofer.de 2 EGEUniversity, Bornova, Izmir 35100, Turkey Tel: + 90232388400 ext. 1923, Fax: + 902323886024, Email: radosveta.sokullu@ege.edu.tr Abstract: — the main goal of Topology Control in Wireless Sensor Networks (WSN) is to establish, monitor and maintain the topology of the network with the purpose to reduce energy consumption thus extend network lifetime, and to minimize radio interference leading to a higher network throughput. In this paper we propose a unified approach for Topology Control in IEEE 802.15.4-based WSN, the de facto standard for low-rate wireless personal area networks (LR-WPANs) that is of interest for many WSN applications. Additionally, we define a performance matrix for Topology Control and investigate through simulation the impacts of node mobility, node density, and traffic patterns. Keywords: Topology control, IEEE 802.15.4, ZigBee, discovery, formation, management 1. Introduction Wireless sensor networks (WSNs) have been an active research area for a number of years now and received increasing interest due to their great number of potential applications. Most of the attention has been given to the medium access (MAC) protocols since they play an important role in wireless communications for saving energy in a single node, taking into account that one of the most important requirements in designing WSN is power efficiency. Recently Topology Control (TC) has received more and more attention in WSN. While WSN applications are usually optimized by the underlying network topology, it was recognized that TC solutions and algorithms are the best way for optimizing the performances of the WSN as a whole. Taking into account that without TC algorithms in place, a randomly connected WSN may suffer from short network lifetime, poor network utilization, high interference, considerable reduction of capacity, high end-to-end delay and robustness to frequent node mobility, one can see the TC in WSN as a key issue of very high importance. The main goal of TC in WSN is to establish, monitor and maintain the topology of the network with the purpose to reduce energy consumption, extending this way network lifetime, and minimize radio interference leading to a higher network throughput [4]. In order to better investigate TC in WSN and compare existing solutions a unified approach for TC is a good starting point. This way the challenging research issues are clearly identified and working solutions can be effectively developed. IEEE 802.15.4 [1] has been used as a common reference scheme in our work, which, however, does not necessarily mean that the unified approach would be applicable only to IEEE 802.15.4 networks. IEEE 802.15.4 is the de facto standard for low-rate wireless personal area