A UWB localization scheme for LOS and NLOS environments using orthogonal codes

A time difference of arrival (TDOA) impulse radio localization scheme based on orthogonal codes is proposed for the positioning systems with multiple mobile nodes. In the proposed scheme, pre-deployed anchors broadcast their unique IDs synchronously and periodically. A two-step localization procedure is carried out by the mobile node. Three anchors with the strongest signal energy are selected and the TDOA of these three signals is measured for location estimation. The orthogonal codes are used to completely cancel the interference between signals from multiple anchors. Simulation results are presented to show the accuracy of the proposed localization scheme in both LOS and NLOS environments. Furthermore, the system performance under different parameter settings are discussed in detail.