As much as accurate or precise position estimation is always desirable, coarse\naccuracy due to sensor node localization is often sufficient. For such level of\naccuracy, Range-free localization techniques are being explored as low cost\nalternatives to range based localization techniques. To manage cost, few location\naware nodes, called anchors are deployed in the wireless sensor environment.\nIt is from these anchors that all other free nodes are expected to estimate\ntheir own positions. This paper therefore, takes a look at some of the\nforemost Range-free localization algorithms, detailing their limitations, with a\nview to proposing a modified form of Centroid Localization Algorithm called\nReach Centroid Localization Algorithm. The algorithm employs a form of\nanchor nodes position validation mechanism by looking at the consistency in\nthe quality of Received Signal Strength. Each anchor within the vicinity of a\nfree node seeks to validate the actual position or proximity of other anchors\nwithin its vicinity using received signal strength. This process mitigates multipath\neffects of radio waves, particularly in an enclosed environment, and\nconsequently limits localization estimation errors and uncertainties. Centroid\nLocalization Algorithm is then used to estimate the location of a node using\nthe anchors selected through the validation mechanism. Our approach to localization\nbecomes more significant, particularly in indoor environments,\nwhere radio signal signatures are inconsistent or outrightly unreliable. Simulated\nresults show a significant improvement in localization accuracy when\ncompared with the original Centroid Localization Algorithm, Approximate\nPoint in Triangulation and DV-Hop.
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