Omnidirectional Mobile NLOS Identification and Localization via Multiple Cooperative Nodes

This paper presents an Omnidirectional mobile target-node (TN) localization technique in nonline-of-sight (NLOS) scenarios. Here, a TN cooperates with base-nodes (BNs) with antenna-arrays to allow them to find its position via time-of-arrival (TOA) and direction-of-arrival (DOA) measurements. When line-of-sight (LOS) channel is available, each BN localizes TNs in its coverage area with reasonable accuracy. However, when LOS channel is obstructed, considerable localization error is generated. To avoid NLOS error, a technique is proposed to identify if a TN is in the LOS of multiple BNs or not. The technique enables BNs to determine and localize their shared reflection points, and to localize NLOS TNs. The paper assumes single-bounce-reflection NLOS channel between BNs and TNs. In NLOS scenarios, when three or more reflection points are shared by a TN and multiple sets of BNs, the shared reflection points are localized via DOA fusion, and then the TN is localized via TOA fusion. The equations for NLOS identification, shared reflection points determination and localization and NLOS TN localization are theoretically derived. Simulations are conducted to evaluate the proposed technique in terms of the probability of false alarm and misdetection of NLOS identification and shared reflection points determination, and NLOS TN localization accuracy.