  Global navigation satellite systems provide accurate positioning nearly
worldwide. However, in the urban canyons of dense cities, buildings block and
reflect the signals, causing multipath errors. To mitigate multipath errors,
knowledge of the distribution of the reflection delays is important.
Measurements of this distribution have been done in several dense cities, but
it is unknown how the delay distribution depends on the depth of the urban
canyon. To fill this gap, we simulated reflection scenarios in 12 different
environments: from suburban to deep urban canyon. Subsequently, we analyzed the
resulting delay distributions. This paper presents these distributions, and a
method to estimate them using the number of received satellites. According to
our simulation, the multipath delays follow gamma distributions, whose shape
parameters decrease when the urban canyon depth increases. A quadratic model
can estimate the shape parameter using the number of received satellites.
Consequently, depending on the number of received satellites, the distribution
of the reflection delays can be estimated. This information can be combined
with prior knowledge from other methods for improved multipath delay
estimation. In the future, for more realistic results, the effects on signals
that are reflected multiple times and environments other than urban canyons
should be simulated.
