DOI 10.1007/s11276-007-0017-x Controlled sink mobility for prolonging wireless sensor networks lifetime Stefano Basagni · Alessio Carosi · Emanuel Melachrinoudis · Chiara Petrioli · Z. Maria Wang C  Springer Science + Business Media, LLC 2007 Abstract This paper demonstrates the advantages of using controlled mobility in wireless sensor networks (WSNs) for increasing their lifetime, i.e., the period of time the network is able to provide its intended functionalities. More specif- ically, for WSNs that comprise a large number of statically placed sensor nodes transmitting data to a collection point (the sink), we show that by controlling the sink movements we can obtain remarkable lifetime improvements. In order to determine sink movements, we first define a Mixed Integer Linear Programming (MILP) analytical model whose so- lution determines those sink routes that maximize network lifetime. Our contribution expands further by defining the first heuristics for controlled sink movements that are fully distributed and localized. Our Greedy Maximum Residual Energy (GMRE) heuristic moves the sink from its current location to a new site as if drawn toward the area where nodes have the highest residual energy. We also introduce a simple distributed mobility scheme (Random Movement or S. Basagni () Department of Electrical and Computer Engineering, Northeastern University e-mail: basagni@ece.neu.edu A. Carosi · C. Petrioli Dipartimento di Informatica, Universit` a di Roma “La Sapienza” e-mail: carosi@di.uniroma1.it C. Petrioli e-mail: petrioli@di.uniroma1.it E. Melachrinoudis · Z. M. Wang Department of Mechanical and Industrial Engineering, Northeastern University e-mail: emelas@coe.neu.edu Z. M. Wang e-mail: zmwang@coe.neu.edu RM) according to which the sink moves uncontrolled and randomly throughout the network. The different mobility schemes are compared through extensive ns2-based simu- lations in networks with different nodes deployment, data routing protocols, and constraints on the sink movements. In all considered scenarios, we observe that moving the sink always increases network lifetime. In particular, our experi- ments show that controlling the mobility of the sink leads to remarkable improvements, which are as high as sixfold com- pared to having the sink statically (and optimally) placed, and as high as twofold compared to uncontrolled mobility. Keywords Wireless sensor networks . Controlled mobility . Mobile sensor networks 1 Introduction Recent years have witnessed an increasing interest in wire- less sensor networks (WSNs). These networks are made up of wireless nodes endowed with sensing capabilities that are deployed for implementing a host of different applications. Typical examples of WSN applications include environmen- tal monitoring, independent assisted living, disaster assess- ment and recovery, control of industrial processes, etc. [3, 8]. From a networking perspective, WSNs generally follow the well-established ad hoc paradigm of communication: Data delivery between any two nodes follows a multi-hop route. Differently from ad hoc networks, where any two nodes can be source and destination of data packets, in WSNs data generated by the sensor nodes are sent to one or more data collection points (the sinks). Sinks are considered resource-rich, i.e., energy, processing power and memory are not considered a limitation for their prolonged function- ing and operations. Sensor nodes are instead usually quite Springer Wireless Netw (2008) 14:831–858 Published online: 7 February 2007