Abstract:
In wireless sensor networks, the location of sensor nodes that generate information in application
such as target tracking, geographic routing , environmental monitoring and forest fire monitoring
are very essential.
Localization techniques are used to estimate the locations of the unknown nodes in a network using
the available few anchors in network and inter-sensor measurements such as time different of
arrival, angle of arrival and connectivity, and of which the three are categorized under range based
localization algorithm and the last one is under range free localization algorithm.
In localization of unknown sensor nodes in wireless sensor networks, the straight forward solution
is installing the GPS in every sensor nodes. But it is infeasible due to lack of line-of-sight in indoor
applications, high network cost because of energy consumption and hardware cost.
In the localization algorithms, the range based algorithms are better in location accuracy but they
need additional hardware requirement and energy which is the tradeoffs. In the case of range free
localization algorithms, they are cost and energy efficient but with less localization accuracy. Since
most of the wireless sensor network applications need coarse localization accuracy, range free
localization algorithms are more effective than the range based ones, taking into consideration the
tradeoffs. Among range free localization algorithms APIT, DV-hop and Centroid localization
algorithms are the popular ones.
In this thesis, we proposed improved APIT localization algorithm by developing novel and simple
Point in triangle test to minimize the probability of wrong judgement of whether the unknown
sensor node is inside triangle formed by the three anchor nodes or outside the triangle.
We have evaluated the performance of both the improved APIT and the original APIT based on
the localization error, and the simulation experiment result show that improved APIT localization
algorithm has better performance than the original APIT. Accordingly localization error rate of
improved APIT localization algorithm is 26%, while localization error rate of APIT localization
algorithm is 31% when anchor node percentage is 25% of the total sensor nodes.
