18-06-2012, 02:53 PM
Open issues in routing techniques in ad hoc wireless sensor networks
Open issues in routing techniques.doc (Size: 53 KB / Downloads: 80)
Abstract:
Ad hoc sensor networks are ad hoc networks that are characterized by decentralized structure and ad hoc deployment. Sensor networks have all the basic features of ad hoc networks but to different degrees – for example, much lower mobility and much more stringent energy requirements.
Introduction
Consider a wireless network made up of units that perform both measurements and communications. These units are totally independent and are capable of recording data from sensors. The mobility of these units is very low but the data forwarding strategy is robust enough to be fault tolerant and to allow occasional mobility among units.
Low Energy Consumption
Protocols for MANETs are designed for communication among laptops. Even though laptops are battery-powered, their power budget far exceeds that of a node in a wireless sensor network. Such nodes are often deployed in remote locations. Whether powered by batteries, solar energy, or some other method, reducing energy consumption lessens the weight or extends the lifetime of the package and makes the sensor easier to conceal. Each node in a wireless sensor network only needs to record, transmit, and forward data, unlike a laptop which might have to perform much more complex tasks. As a result, the computational engine in a sensor node consumes significantly less energy than a laptop, and communications must likewise use less energy.
Low mobility
Sensor networks differ from MANETs in a very important way and that is in mobility. A MANET is a more general case where the participating laptops can either be stationary or move randomly with a random speed. As nodes within a MANET move, they move out of range of their neighbors and hence are no longer able to communicate with the old neighboring nodes and come within range of new nodes. Hence the mobility introduces the problem of fault tolerance. An ideal routing protocol for MANET should be able to deliver data packets from source to destination even when some of the intermediate nodes move away from their neighbors range.
Self-configuring nature
Ad hoc wireless sensor networks are self-configuring in nature. This can be considered an added feature to the existing ad hoc nature of the network. The network is adaptable to the changing requirements and is able to diagnose when a link / sensor node goes down and when it comes up. There are two main schemes to design a wireless sensor network, the address centric scheme and the data centric scheme. The address centric scheme has been used by various routing protocols such as LAR, GSPR, and DREAM etc. In this scheme we assign IP addresses to each sensor node, simplifying the process of routing. This concept is similar to that of normal wired networks. A unique IP address will help the source sensor node to know the sensor node to which data must be routed. However in [5] a new concept of data centric model is presented which is not address oriented. The mechanism and goal of self-configuration in these networks is different from those of the address centric scheme.
Conclusion
In this paper we have evaluated the necessary features of the routing protocols for general wireless sensor network like PODS [9]. Current research into routing protocols for MANETs and ad hoc sensor networks tend to make many tradeoffs in various features and are generally tested in a much regulated environment. As seen from the paper that the needs and requirements of routing protocols for general ad hoc sensor networks is very unique compared to routing protocols for MANETs and other sensor networks.