Closed-form approximation for the outage capacity of OFDM-STBC and OFDM-SFBC systems

The combination of orthogonal frequency-division multiplexing (OFDM) and space-time or space-frequency block coding (STBC or SFBC) has been shown to be a simple and efficient means to exploit the spatial diversity in frequency-selective fading channels. From a general broadband multiple-input-multiple-output(MIMO) channel model, we derive a tight analytical approximation for the outage capacity of such systems assuming that the channel is known at the receiver and unknown at the transmitter. This expression is a simple function of the channel and system parameters. Numerical results are provided to demonstrate the excellent accuracy of the derived approximation in all cases.