The Geometry of Overhearing and Its Application for Location Estimation in Cellular Networks

Realizing the precise location of mobile terminals in a severely non-line-of-sight (non-LOS) propagation environment is still a challenging problem. This paper proposes a new location estimation technique for cellular networks through which a mobile terminal's position can be derived by counting the number of overheard beacon packets that power-controlled mobile terminals transmit. The geometry of overhearing is also introduced to model the relation between the position and the number of overheard packets. In this technique, unlike other existing radiolocation methods, neither the absence of an LOS path nor the existence of multipath propagation affects the performance. Furthermore, it is shown that both decreasing the radius of the cell's coverage area and increasing the density of nodes result in significant improvements in the accuracy of estimation. It is also shown that the mobility of nodes has no impact on the performance of the proposed scheme. These features make the proposed technique an attractive solution for dense urban environments, where the radius of the cell's coverage area is limited, and an LOS path hardly exists. Simulation results are used to validate the effectiveness of the proposed technique.