On the Optimality of WLAN Location Determination Systems
On the Optimality of WLAN Location Determination Systems
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Date
2003-04-04
Authors
Youssef, Moustafa A.
Agrawala, Ashok
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Abstract
This paper presents a general analysis for the performance of WLAN
location determination systems. In particular, we present an analytical
method for calculating the average distance error and probability of error
of WLAN location determination systems. These expressions are obtained
with no assumptions regarding the distribution of signal strength or the
probability of the user being at a specific location, which is usually
taken to be a uniform distribution over all the possible locations in
current WLAN location determination systems. We use these expressions to
find the optimal strategy to estimate the user location and to prove
formally that probabilistic techniques give more accuracy than
deterministic techniques, which has been taken for granted without proof
for a long time. The analytical results are validated through simulation
experiments. We also study the effect of the assumption that the user
position follows a uniform distribution over the set of possible
locations on the accuracy of WLAN location determination systems. The
results show that knowing the probability distribution of the user position can reduce the number of access points required to obtain a given
accuracy. However, with a high density of access points, the performance
of a WLAN location determination system is consistent under different
probability distributions for the user position.
UMIACS-TR-2003-29