Performance analysis of macroscopic diversity combining of MIMO signals in mobile communications

In this paper, the system model and performance analysis of macroscopic diversity combining (MDC) of multiple-input multiple-output (MIMO) systems are presented for mobile cellular communications. For point-to-point dual antenna array (DAA) systems applying directional beam forming, if the antenna spacing is insufficient or the scattering environment does not provide completely uncorrelated channels then the MIMO system capacity deteriorates. In addition, the shadowing component of the directional signal is a common factor among the scattered channels resulting in significant reductions in obtainable channel capacity. Therefore, in this paper, a MDC topology is proposed to enable the mobile terminals (MTs) and base stations (BSs) to adaptively select the most uncorrelated MIMO channels to obtain higher data rates and lower signal outage. The channel capacity as well as its upper and lower bounds are derived for the MIMO-based MDC system. Compared to a single communicating MIMO systems pair, the results show that the macroscopic diversity MIMO communication topology enables a larger numbers of uncorrelated shadowed and scattered channels to exist, and therefore, significant improvements of enhanced channel capacity and reduced outage can be obtained.