Modified RWGH and Positive Noise Mitigation Schemes for TOA Geolocation in Indoor Multi-hop Wireless Networks

Time of arrival (TOA) based geolocation schemes for indoor multi-hop environment are investigated and compared to some of conventional geolocation schemes such as least squares (LS) or residual weighting (RWGH). The multi-hop ranging involves positive multi-hop noise as well as non-line of sight (NLOS) and Gaussian measurement noise, so that it is more prone to ranging error than one-hop range. In this paper, RWGH algorithm is modified by adapting weighted residual normalization considering the number of hops taken to measure each ranging. The iterative positive noise mitigation schemes are further developed by using distance enlargement test (DET) to mitigate the multi-hop ranging noise. Simulation results show that the proposed modified RWGH algorithms show 5 to 25% smaller average estimation error compared to LS and RWGH for both positive noise mitigation and no mitigation cases, and the positive noise mitigation schemes provide 28 to 42% error mitigation compared to no mitigation schemes.