  In this paper an improved version of the graded precision localization
algorithm GRADELOC, called IGRADELOC is proposed. The performance of GRADELOC
is dependent on the regions formed by the overlapping radio ranges of the nodes
of the underlying sensor network. A different region pattern could
significantly alter the nature and precision of localization. In IGRADELOC, two
improvements are suggested. Firstly, modifications are proposed in the radio
range of the fixed-grid nodes, keeping in mind the actual radio range of
commonly available nodes, to allow for routing through them. Routing is not
addressed by GRADELOC, but is of prime importance to the deployment of any
adhoc network, especially sensor networks. A theoretical model expressing the
radio range in terms of the cell dimensions of the grid infrastructure is
proposed, to help in carrying out a deployment plan which achieves the
desirable precision of coarse-grained localization. Secondly, in GRADELOC it is
observed that fine-grained localization does not achieve significant
performance benefits over coarse-grained localization. In IGRADELOC, this
factor is addressed with the introduction of a parameter that could be used to
improve and fine-tune the precision of fine-grained localization.
