Mobile Wireless Sensor Networks: Architects for Pervasive Computing

A mobile wireless sensor network owes its name to the presence of mobile sink or sensor nodes within the network. The advantages of mobile wireless sensor network over static wireless sensor network are better energy efficiency, improved coverage, enhanced target tracking and superior channel capacity. In this chapter we will present and discuss different classifications of mobile wireless sensor network as well as hierarchical multi-tiered architectures for such networks. This architecture makes basis for the future pervasive computing age. The importance of mobility in traditional wireless sensor network (WSN) is highlighted in this chapter along with the impact of mobility on different performance metrics in mobile WSN. A study of some of the possible application scenarios for pervasive computing involving mobile WSN is also presented. These application scenarios will be discussed in their implementation context. While discussing the possible applications, we will also study related technologies that appear promising to be integrated with mobile WSN in the ubiquitous computing. With an enormous growth in number of cellular subscribers, we therefore place the mobile phone as the key element in future ubiquitous wireless networks. With the powerful computing, communicating and storage capacities of these mobile devices, the network performance can benefit from the architecture in terms of scalability, energy efficiency and packet delay, etc. For mobile wireless sensor networks, there are basically two sensing modes, local sensing and remote sensing. By allowing and leveraging sink mobility and sink coordination, mobile WSN can achieve the goal of lower and balanced energy consumption with the following features:  Single-hop clustering. By allowing only single hop transmission between sensor and sink node, most previous multi hop relaying sensor nodes may become unnecessary. In fact, sensor nodes can enter sleep mode until the sink approaches. Therefore, the original energy budget for multi hop relaying can be saved.  Sink mobility and coordination. For a delay tolerant application, single mobile sink in fact equals virtually multiple static sinks at different positions. Multi-sink deployment can bring more uniform energy dissipation, therefore the possibility of energy hole will be reduced and network coverage will be improved. 1