Low-order Models for Spatial Diversity Systems Including Real Antenna Characteristics

In order to provide highly reliable transmission links in mobile communications, wireless systems offering multiple branches for antenna diversity are recommended due to the property of mitigating fading effects in multipath environments. An accurate prediction of the performance of those diversity systems requires a complete description of antenna radiation behavior for the exact modeling of the interactions between real antenna configurations and suitable multipath channel scenarios. Closed-form solutions that account for real antenna radiation patterns and mutual coupling can be achieved applying a spherical eigenmode (SME) expansion of antenna radiation fields. Combining this field decomposition with a stochastic description of the communication channel, the presented analysis establishes an analytical framework for the calculation of antenna envelope correlation, mean effective gain and diversity performance that speeds up the computation of link budgets especially for large antenna arrays at the receiver.