Outdoor Neighbor-Assisted Localization Algorithm for Massive MIMO Systems

Localization is an important technique in wireless systems as it provides fundamental support for many emerging location-aware applications. This paper proposes a neighbor-assisted localization algorithm to determine the coordinates of a stationary User Equipment (UE) placed in an outdoor environment. The proposed algorithm allows the base station to determine the position of a Target UE (T-UE) with obstructed channel conditions through the assistance of neighboring UEs having Line Of Sight (LOS) components with the base station. Having LOS components, the neighboring UEs can easily be localized with high accuracy at the base station level. A minimum of two previously localized neighbors is required to assist in determining the position of the T-UE through multi-stage processing. The first stage uses one neighbor to calculate the distance separating it from the T-UE based on the signal strength. This distance helps to draw a circle crossed by a line identifying two position candidates using oriented beamforming. The second neighbor is then used to remove the ambiguity on the correct position candidate by the mean of the distance separating it to the T-UE. Our algorithm exploits the capabilities of neighbor discovery, oriented beamforming, and millimeter waves to provide accurate position estimate for UEs experiencing harsh channel conditions that make direct localization at the base station a challenging task. We also show that it is possible to further enhance the localization accuracy by simply increasing the search interval.