Localization enhancement by additional nodes in wireless networks

Next generation mobile networks frequently offer services and applications that require the stations position. It is well known that adding nodes to an existing wireless network enhances the localization accuracy of the network nodes. We exploit a recent compact expression of the Cramer-Rao bound to identify the nodes whose localization is improved. Further, we define the exact conditions for error reduction. In particular, in a planar network, an additional node must have at least three connections, not all of them to anchors, to affect the accuracy. We also show that the accuracy improvement is limited by a bound, which is independent of the number of additional nodes. Finally, we provide numerical examples that shed some light on the accuracy improvement.