A closed-form approximation of the outage probability for distributed MIMO systems

The instantaneous capacity of multiple-input multiple-output (MIMO) systems over Rayleigh fading channel is known to follow a normal probability distribution when the number of transmit and receive antennas is large. In this paper, we extend this result for distributed MIMO (DMIMO) systems by deriving a closed-form approximation of the outage probability which becomes tighter as the rate or the number of nodes and antennas of the system increases. This expression can be used to easily evaluate the outage probability of DMIMO systems, both for downlink and uplink cases. We also utilize this expression to compare the theoretical throughput performance of MIMO and DMIMO systems and show that DMIMO systems can achieve a throughput gain over their MIMO counterparts by taking advantage of spatial diversity.