Random coding error exponent for OSTBC Nakagami-m fading MIMO channel

In this paper, we derive the closed-form Gallager's random coding error exponent expression for Orthogonal Space-Time Block Coded (OSTBC) Nakagami-m fading multiple-input multiple-output (MIMO) channels. We assume that the transmitter has no channel-state information (CSI) and perfect CSI at the receiver. We get the knowledge of an elementary tradeoff between the communication reliability and information rate of the OSTBC Nakagami-m fading MIMO channels by this measure. At a given rate below the channel capacity, it enables us to find the necessary codeword length to achieve predefined error probability. We derive the expression for the cutoff rate and ergodic capacity based on easily computable Meijer G-function. Numerical results are presented and verified via Monte-Carlo simulation.