Capacity analysis of highly Correlated Rayleigh Fading Channels for Maximal Ratio Combining Diversity

In this paper, we derive closed form expressions for Capacity per unit bandwidth (Spectrum Efficiency) of Correlated Rayleigh Fading Channels under Maximal Ratio Combining Diversity for High Correlation between pilot and the signal. The spectrum efficiency expressions are derived for M diversity branches under adaptation policies, such as (i) Optimal Power and Rate Adaptation (OPRA) policy, (ii) Optimal Rate Adaptation (ORA) policy (iii) Channel Inversion with Fixed Rate (CIFR) policy, and (iv) Truncated channel Inversion with Fixed Rate (TIFR) policy. If M branch signals are highly correlated and if space diversity is exercised using a SIMO system, the spectrum efficiency achieved is higher compared to that achieved when the signals are uncorrelated and have no diversity. This forms the focal point of this paper. Analytical results show accurately that OPRA policy provides the highest capacity over other adaptation policies. The spectrum efficiency for all four policies and outage probability for the highly correlated case are derived, plotted and analyzed in detail in this work.