Cooperative non-line-of-sight localization technique for indoor wireless network

This paper presents a cooperative localization technique for indoor wireless network under non-line-of-sight scenario. In the absent of line-of-sight path, the technique will make use of Non-Line-of-Sight NLOS paths´ Time of Arrival (TOA) and Angle of Arrival (AOA) measured at both mobile and reference devices to located the mobile device. Briefly, a line that contains the possible mobile device position is derived for each NLOS path-referred to as LPMD and intersection points of these LPMDs are used to estimate the mobile position. The main contribution of this paper is that unlike existing techniques which require an arbitrary threshold value to select appropriate LPMDs or intersection points for localization, error variance of each intersection point is first determined analytically and it depends on many factors such as distance travelled and relative alignments of LPMD pairs that form the intersection point. Our proposed technique then construct a Gaussian weighting function of each intersection point using the calculated error variance, and assign weights to every intersection points based on the proximity of these points to the intersection point of interest by using Gaussian function. The intersection point with the highest weighted can be used to determine the mobile position without the need for an arbitrary threshold value. Simulation in an indoor environment shows that the proposed localization technique is robust and outperforms previous NLOS localization techniques.