AOA Assisted NLOS Error Mitigation for TOA-Based Indoor Positioning Systems

One of the major challenges for TOA-based accurate indoor positioning systems is the blockage of the LOS path, or equivalently direct path (DP), due to obstructions. Since accurate ranging of these systems depend on the detection of the DP between the transmitter and receiver, significant errors will be introduced into the ranging measurements once the DP cannot be detected. This condition is hence called the undetected direct path (UDP) condition. Owing to the fact that indoor wireless channels exhibit rich multipath propagation, the multipath components other than the DP may be utilized in mitigating errors occurring in UDP areas. In this paper, we introduce a method based on both TOA and AOA information from other multipath components to substantially mitigate the ranging error. We present our results as a comparison with commonly used methods for TOA-based ranging and we show that our proposed technique outperforms these traditional methods.