Applications of Sensor Networks

Wireless Sensor Networks are used to build wide variety of applications . The apps range from agriculture apps to defense apps. All applications involve many sensor nodes, which collect data from the deployed site and this collected data is used for some specific purpose. I will give some examples of applications which are built using sensor networks.

• Military or Defense Applications
• Agriculture Applications
• Environment and Weather Monitoring Applications
• Habitat Monitoring Applications
• Applications for Home Automation
• Applications for Industries
• Traffic Surveillance and Road Monitoring Applications
• Applications for Health Monitoring , which is very broad area called as Body Area Network
• Pollution Monitoring Applications
• Applications to predict Natural Calamities
• Applications for Surveillance and Intrusion Prevention
• Structure Monitoring Applications like bridge monitoring apps

Addressing in WSN

Several approaches have been proposed for addressing in WSN(Wireless Sensor Network) . I will brief about some approaches which I have read.

"Lease based addressing for event driven wireless sensor networks" proposes to use a network level unique address to use a node temporarily. Three phases are proposed by this paper, they are boot up phase , address request phase and address release phase. Initially when the node boots up, it assigns itself a link local address and waits for the broadcast message from sink. Once the node receives the broadcast message from sink it send address request message to sink. The sink maintains a table of address assigned and table of address unassigned. If the sink has any unassigned address then the sink assigns an unique address to the requesting node. The node utilizes this address for required duration and then releases the address , the node uses release address message for this purpose.

"Distributed address assignment" specified in ZigBee standard provides a method to distribute addresses available at the coordinator among all nodes. It gives a mathematical formula, which is utilized to distibute address among the nodes. The coordinator distributes the available addresses to its immediate children, every router child is given equal number of addresses and non router child is given a single address. Every router node in turn assigns available addresses to its children (differentiating between router child and non router child). This method may not be very relevant if the network does not grow uniformly .

"A novel approach for dynamic address assignment in wireless sensor networks" proposes to use only a part of available addresses for initial distribution . This initial distribution is done as specified in ZigBee. Later if any other node requires more addresses then it requests for more addresses from its parent, which is allocated if the parent has required number of addresses else the request is relayed till the initial server. Th parent also may ask some of its children to return unused addresses if the parent is in need of addresses. This method is applicable even if the network grows non uniformly.

"Dynamic Address Allocation for Management and Control in WSN" proposes a novel method. The address server sends a broadcasts message once the network starts up and in turn all nodes select an address dynamically(randomly selected) and send the selected address to the server. The server checks if the address is already in use and if so the server asks the respective node (which ever is newer) to select another address using redo message. If the address is unique then the node is confirmed about the address using assign message. This process continues until the node gets an unique address.

"An energy efficient node address naming scheme for WSN" provides procedures for cluster based sensor networks. Along with the above specified methods there are several other approaches for addressing in WSN, one can refer to the references in the above papers for information on other approaches.