Overview

Realising the potential benefits of using mobile nodes in sensor networks has shifted a fair amount of interest in exploration of mobility in wireless sensor networks and also using robots in such networks. Currently research in the area of mobile sensor networks covers aspects such as clustering, routing, localisation, node relocation and various other application specific properties where use of a limited number of mobile nodes can significantly improve various characteristics of a sensor network. The main advantages to be gained from a mobile sensor network in comparison to its static counterpart, are:

1. prolonging the network lifetime,
2. improving network coverage and
3. the ability to repair network holes.

Introducing mobility to wireless sensor networks enables development of applications with a new set of requirements and functionalities that conventional static sensor networks would not be able to provide or efficiently support. Use of mobile nodes in sensor networks opens up a vast amount of new possibilities in this domain. However as solutions to current shortcoming are unravelled other solutions which were applicable in a static sensor network now render useless, hence new challenges are exposed. For example modifications to current communication protocols have been suggested which takes into account mobility of sensor nodes. [14,13] Suggest adoptions of the LEACH(Low-Energy Adaptive Clustering Hierarchy)[15] protocol in order make it suitable for more dynamic and mobile environments. These adoptions are mainly centred around reinitialisation and frequent updates of local clusters upon nodes joining or leaving them. Likewise new methods for localisation[16,17] have been suggested that improve upon previous localisation methods. Such modifications and evolution for various aspects of sensor networks are briefly covered in the following section.