Arrival paths in ultra wideband channels

The statistics of multipath arrival in an indoor multipath channel have been obtained based on a 3-D ray-tracing model. It is found that a Rayleigh distribution is a reasonable approximation assuming all multipath components below a -10 dB threshold with respect to the peak power path are neglected. The number of arrival paths in a small time interval (used to define a bin in a RAKE receiver) is found to follow an exponential distribution and the corresponding parameters are given for different time bin sizes. It is pointed that when the bin size (equivalent to the time resolution of the receiver) is greater than 2 ns, the possibility of more than one path arriving in a particular bin is greater than 50%. These are important considerations in both receiver design and MIMO channel models. An angular power spectrum analysis is also presented; this indicates that multipath spatial clusters occur which could be isolated in the receiver. The properties of these multipath clusters vary strongly with building architecture