2012 Volume 1 Issue 5 Pages 171-176
Ultra wideband (UWB) technology in low band has being attracted considerable attention for high-speed and real-time transmission from inside to outside human body. However, it suffers from large attenuation and shadow fading in human tissues. A diversity technique is expected to provide effective improvement on its communication performance. This study aims to derive an approximate model for correlated in-body to on-body diversity channel and clarify the diversity effect. First, correlated statistical distribution between each two single signals is approximated as a lognormal sum distribution. Then two flexible parameters s1 and s2 in the lognormal sum approximation are optimized to obtain the probability density function (PDF) of the diversity channel. Finally the average bit error rates (BERs) are calculated theoretically to clarify the diversity effect, and its validity is verified by computer simulations.