Signal-strength-based cellular location using dynamic window-width and double-averaging algorithm

For signal-strength-based cellular location systems the primary sources of error are Rayleigh fading and log-normal shadowing. Variations in the signal strength can be as great as 30-40 dB over distances on the order of a half wavelength. Signal-strength averaging can help, but there are two restrictive factors. The first is that the two kinds of fading have different probability density function and the optimum estimation of the local mean signal strength can not be obtained in the same reference. The second is that low-mobility MS may not able to average out the effects of the fading. Therefore this paper suggests a double-averaging algorithm with dynamic widow-width to combat both factors mentioned above. The results of computer simulation proved that our methods improve the location accuracy by 30% more than traditional methods. Also, with the aid of dynamic window-width, sufficient location accuracy can be obtained while the MS has a low mobility.