Sink and Relay Mobility Based Energy Conservation Techniques for WSN: A Survey

Wireless Sensor Networks are gaining more and more importance in present era. Recent Advances in WSN have extended the applicability of these to wide range of real time applications. One of these recent advances in WSN is invention of Heterogeneous Wireless Sensor networks (HWSN). Compared to Homogenous, Heterogeneous have large curve of applicability. However, whether it is Homogenous WSN or Heterogeneous WSN consumption of energy is un-avoidable. In most of the sensor applications energy is one of the scarce resource. Hence, the main goal of any application using WSN is to spend less energy and extend the lifetime of the WSN. Broadly, the energy conservation techniques in Wireless Sensor Networks are classified as Data driven based, Mobility based and Duty cycle based. In this paper, we are presenting a survey on mobility based energy conservation techniques for sensor networks (both homogeneous and Heterogeneous WSNs). Mobility of nodes could be in the form of sink mobility, relay node mobility or sometimes sensor node mobility. We are discussing in more details on sink mobility and relay node mobility based energy conservation techniques. Present works concentrate only on one aspect of energy conservation. We are also identifying some research gaps in the field of energy conservation in sensor networks considering mobility of nodes in the sensor network.