Small-scale compensation for WLAN location determination systems

To limit the radio map size and the time required to build the radio map, current WLAN location determination system do not handle small-scale variations. This contributes to most of the estimation error in the current systems. We propose a general technique, the perturbation technique, to handle the small-scale variations problem. The system uses user history to detect small-scale variations and then perturbs the signal strength vector entries to overcome it. The results obtained show that the accuracy can be increased by more than 8%. Moreover, the worst-case error is enhanced by more than 60%. We also show that the perturbation technique can help in enhancing the accuracy due to temporal variations in case of change in the environment conditions, thus increasing the accuracy of the current WLAN location determination systems beyond their limits.