Bluetooth Based Wireless Sensor Networks –Implementation Issues and Solutions Srdjan Krco Applied Research Lab, Ericsson Ireland Invited paper Abstract – Wireless sensor networks – networks of small devices equipped with sensors, microprocessor and wireless communication interfaces – are a technology that has gained a lot of interest lately. The broad spectrum of new and interesting applications, ranging from personal health-care to environmental monitoring and military applications, is proposed for such networks. Various wireless technologies, like simple RF, Bluetooth, UWB or infrared might be used for communication between sensors. In this paper the main principles, applications and issues of Bluetooth based wireless sensor networks, as well as an implementation of a simple Bluetooth based sensor network are described. The main problems experienced during the implementation and applied solutions are presented. hardware resources , , ,  and efficient communication protocols , , , , , , , to enable networking and collaboration of smart sensor nodes. In the next section the main principles of wireless sensor networks are given and research issues are explained. Section 3 presents Bluetooth issues related to its use in sensor networks. An implementation of a Bluetooth based sensor network is described in section 4 along with some of the implementation issues and solutions. Section 5 concludes the paper.
2. Wireless sensor networks
Wireless sensor networks comprise number of small devices equipped with a sensing unit, microprocessor, wireless communication interface and power source. In contrast to the traditional sensor networks that are carefully planned and deployed to the predetermined positions, wireless sensor networks can be deployed in an ad-hoc manner. Of course, such deployment requires adequate communication protocols that are able to organize the network automatically, without the need for human intervention. Beside self-organization capability, another important feature of wireless sensor networks is collaboration of network nodes during the task execution. In contrast to the traditional sensor networks where all sensor data is gathered at a server and then analysed and fused, data processing and fusion is now performed by smart nodes themselves. Each node processes raw measurement data in order to decrease amount of data sent over wireless links and forwards only relevant parts to nodes responsible for data fusion. Data-centric nature of the network is yet another specific characteristic of wireless sensor networks. As deployment of smart sensor nodes is not planned in advance and positions of nodes in the field are not determined, it could happen that some sensor nodes end in such positions that they either cannot perform required measurement or the error probability is high. That is why a redundant number of smart nodes observing the same phenomenon is deployed in the field. These nodes then communicate, collaborate and share data, thus ensuring better results (each sensor has its own view of the phenomenon – when these views are combined a better picture of the phenomenon is obtained). Having this in mind, it is more reasonable for a user to send a data request to all sensors monitoring the phenomenon than to send it to one specific sensor node. Using a multicast routing protocol to send messages to all relevant nodes would require unique addressing scheme in the network. However, due to the sheer number of sensors and user requirements (user needs
In , a vision, called ubiquitous computing, of the world where humans and computers were seamlessly united is described. The essence of the vision was the creation of environments saturated with computing and communication in an unobtrusive way. Recently, WWRF (Wireless World Research Forum) and ISTAG (IST Advisory Group) released their visions of the future communication networks , . Both...
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