Recently, a number of empirical models have been introduced in the literature for the behavior
of direct path used in the design of algorithms for RF based indoor geolocation.
Frequent absence of direct path has been a major burden on the performance of these algorithms
directing researchers to discover algorithms using multipath diversity. However,
there is no reliable model for the behavior of multipath components pertinent to precise
indoor geolocation.
In this dissertation, we first examine the absence of direct path by statistical analysis
of empirical data. Then we show how the concept of path persistency can be exploited
to obtain accurate ranging using multipath diversity. We analyze the effects of building
architecture on the multipath structure by demonstrating the effects of wall length and
wall density on the path persistency. Finally, we introduce a comprehensive model for the
spatial behavior of multipath components. We use statistical analysis of empirical data
obtained by a measurement calibrated ray-tracing tool to model the time-of-arrival, angleof-
arrival and path gains. The relationship between the transmitter-receiver separation
and the number of paths are also incorporated in our model. In addition, principles of ray
optics are applied to explain the spatial evolution of path gains, time-of-arrival and angleof-
arrival of individual multipath components as a mobile terminal moves inside a typical
indoor environment. We also use statistical modeling for the persistency and birth/death
rate of the paths. |