25-08-2017, 09:32 PM
Dragging the world towards wireless galaxy
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ABSTRACT
Various sensors are already in a broad use today as part of different devices or as standalone devices connected to a network usually to monitor industrial processes, equipments or installations.
The advancements in technology, wireless communications have enhanced development of small, low power and low cost devices. Such devices when organized into a network, present a powerful platform that can be used in many interesting applications.
Bluetooth is a low cost, short-range, wireless technology with small footprint, low power consumption and reasonable throughput.
Bluetooth wireless technology has become global technology specification for “always on” wireless communication not just as a point-to-point but was a network technology as well.
The kernel of this paper, deals about an implementation of
bluetooth based sensor networks.
INTRODUCTION
The communications capability of devices and continuous transparent information routes are indispensable components of future oriented automation concepts. Communication is increasing rapidly in industrial environment even at field level.
In any industry the process can be realized through sensors and can be controlled through actuators. The process is monitored on the central control room by getting signals through a pair of wires from each field device in Distributed Control Systems (DCS). With advent in networking concept, the cost of wiring is saved by networking the field devices. But the latest trend is elimination of wires i.e., wireless networks.
BLUE TOOTH
Blue tooth operates in the unlicensed ISM band at 2.4 GHZ frequency band and use frequency hopping spread spectrum technique. A typical Blue tooth device has a range of about 10 meters and can be extended to 100meters. Communication channels supports total bandwidth of 1 Mb / sec. A single connection supports a maximum asymmetric data transfer rate of 721 KBPS maximum of three channels.
BLUE TOOTH – NETWORKS
In bluetooth, a Piconet is a collection of up to 8 devices that frequency hop together. Each Piconet has one master usually a device that initiated establishment of the Piconet, and up to 7 slave devices. Master’s Blue tooth address is used for definition of the frequency hopping sequence. Slave devices use the master’s clock to synchronize their clocks to be able to hop simultaneously
BLUE TOOTH BASED SENSOR NETWORK
The main challenge in front of Blue tooth developers now is to prove interoperability between different manufactures’ devices and to provide numerous interesting applications. One of such applications is wireless sensor networks.
Wireless sensor networks comprise number of small devices equipped with a sensing unit, microprocessors, and wireless communication interface and power source.
GATEWAY LOGIC
1.It controls gateway interfaces and data flow to and from sensor network.
2.It provides an abstraction level that describes the existing sensors and their characteristics.
3.It provides functions for uniform access to sensors regardless of their type, location or N/W topology, inject queries and tasks and collect replies.
SENSOR-NETWORK IMPLEMENTATION
The main goal of our implementation was to build a hardware platform and generic software solutions that can serve as the basis and a test bed for the research of wireless sensor network protocols.
Implemented sensor network consists of several smart sensor nodes and a gateway. Each smart node can have several sensors and is equipped with a micro-controller and a bluetooth radio module.
Gate way and smart nodes are members of the Piconet and hence maximum seven smart nodes can exist simultaneously in the network.
For example, a pressure sensor is implemented, as bluetooth node in a following way. The sensor is connected to the bluetooth node and consists of the pressure sensing element, smart signal-conditioning circuitry including calibration and temperature compensation, and the Transducer Electronic Data Sheet (TEDS). These features are built directly into the sensor microcontroller used for node communication control plus memory for TEDS configuration information.
DISCOVERY OF THE SMART SENSOR NODES
Smart sensor node discovery is the first procedure that is executed upon the gateway installation. It goals to discover all sensor nodes in the area and to build a list of sensor’s characteristics and network topology. Afterwards, it is executed periodically to facilitate addition of new or removal of the existing sensors. The following algorithm is proposed.When the gateway is initialized, it performs bluetooth inquiry procedure. When the blue tooth device is discovered, the major and minor device classes are checked. These parameters are set by each smart node to define type of the device and type of the attached sensors. Service class field can be used to give some additional description of offered services. if discovered device is not smart node it is discarded. Otherwise service database of the discovered smart node is searched for sensor services. As currently there is no specific sensor profile, then database is searched for the serial port profile connection parameters. Once connection strings is obtained from the device. Blue tooth link is established and data exchange with smart mode can start.
CONCLUSION
Blue tooth represents a great chance for sensor-networked architecture. This architecture heralds wireless future for home and also for industrial implementation. With a blue tooth RF link, users only need to bring the devices with in range, and the devices will automatically link up and exchange information.Thus implementation of bluetooth technology for sensor networks not only cuts wiring cost but also integrates the industrial environment to smarter environment.Today, with a broader specifications and a renewed concentration on interoperability, manufacturers are ready to forge ahead and take blue tooth products to the market place. Embedded design can incorporate the blue tooth wireless technology into a range of new products to meet the growing demand for connected information appliances.