An efficient adaptive method for estimating the distance between mobile sensors
Résumé
The received signal strength (RSS) is a common
source of information used for estimating the distance
between two wireless nodes, whether these nodes are stationary
or mobile. Minimum mean squared error distance
estimation methods that use the RSS require prior knowledge
of both the variance of the noise and, in the case of
mobile sensors, the dynamics of the nodes’ mobility. In
mobile applications, where low computational complexity
is important, pseudo-optimal estimations are preferred, as
they do not require such information. In this case, the
maximum likelihood estimator (MLE) is often used. In this
paper, we propose an efficient pseudo-optimal log-power
based distance estimation method using RSS under lognormal
shadowing, that improves the MLE. It does not require
a priori knowledge either of the movement dynamics
or of the variance of the noise. The method is based on
adaptively minimizing the variance of the prediction error,
using a random walk model with correlated increments. It is
analytically demonstrated that the distance estimation error
variance of the proposed method improves the MLE in both
the static and mobile cases. We use a simulated velocity
model example to compare its performance with other
algorithms in this group, such as the linear mean square filter
and the Gauss–Newton search.