Keywords: time dispersion definition, what's time dispersion When a signal is transmitted, this sign can undergo a distortion induced by reflections and spread propagation paths in the radio route, and these phenomenons cause that an identical signal finds differing times at its vacation spot. These differing times are credited that to the signal gets there via multiple pathways and in different incident angles. Enough time difference between the arrival moment in time of the first multipath part and the last one is called delay spread. In order to compare different multipath channels also to develop some basic design rules for cordless systems, some guidelines are used to quantify the multipath route. Some of these multipath parameters are the mean excess delay, rms delay pass on, and maximum unnecessary wait, and can be motivated from a electricity delay profile.