An Improved DV-Hop Localization Algorithm In Ad Hoc Networks

A fundamental goal of network computing is to make the interactions between people and the environment more effectively. Location, where people are making a direct connection with the environment, is an important element in the physical world. With the development of mobile communications technology, the demand for location information is becoming more and more urgent. Moreover, in many cases, location information plays a crucial role. For example, in military tactical communications network, location information of nodes is the key basis for operational command, the tactical information of nodes are highly related with the location where the nodes are. The tactical information will be meaningless without the support of the location information. In the case of disaster rescue, it is meaningful only that the perceived environmental information is bundled with the location information, sometimes it only has to send back the location information. Locating the nodes in network can reduce the consumption of the process of finding and updating the routing, improve the efficiency of routing; offer the network namespace; achieve the load balance of network and make network topology to take self-configuration and so on.Now the widely used technologies of mobile communications are all based on a fixed base station, which has restricted the realization of locating. The traditional GPS and other satellite navigation positioning system, thanks to the environment (indoor, tunnels, etc.), cost, power consumption and many other factors, the demand for real-time location of users and applications of some special occasions has also been constrained. As a network without a fixed communication facilities, the Ad Hoc networks, can make up the deficiency that the traditional mobile communication network depends on the fixed telecommunications facilities (such as base stations), when in the wild places or places without fixed base stations, the communication tasks can't be completed. Ad Hoc networks are now widely used in military operations, emergency handling, disaster relief and other important occasions. The research on using a certain algorithm to make the nodes in Ad Hoc network take self-localization is quite necessary.However, due to the communication mechanism of Ad Hoc networks, that is, the message has to take a multi-hop packet to get to the destination, and the dynamic changes of network topology and other reasons, many of the traditional location algorithm can not adapt to Ad Hoc network, neither the position accuracy or the coverage rate can not get good result when used in other environment. To address the problems above, this paper proposes a distance-assisted DV-DScale localization algorithm.The cumulative distance value is no longer directly used for maximum likelihood estimation to localization, but as scale to amend the straight-line distance between nodes and estimate the position information of nodes. Mathematical derivation and simulation analysis show that the new algorithm reduces the physical location differences caused by the multi-hop communication mechanism of Ad Hoc network. It also amends the cumulative distance between hop sections, improves the traditional algorithm's deficiencies of positioning accuracy when in uneven distribution or sparse network. Both in dense networks or sparse network, the new algorithm achieves good self-positioning of nodes in Ad Hoc network, in the same time, it can get higher positioning accuracy, compared to the traditional algorithm.