Optimization of Multimedia Progressive Transmission Over MIMO Channels

This paper studies the optimal transmission of multimedia progressive sources, which require unequal target error rates in their bitstream, over multiple-input-multiple-output (MIMO) channels. First, we derive the information outage probability expression of a space-time code for an arbitrarily given piecewise-linear diversity-multiplexing tradeoff (DMT) function and the conditions for the existence of a crossover point of the information outage probability curves of the space-time codes. We prove that as long as the crossover point of the outage probabilities exists, as spectral efficiency increases, the crossover point in the signal-to-noise ratio (SNR) monotonically increases, whereas that of the outage probability monotonically decreases. This analysis can be applied to any space-time code, receiver, and propagation channel with a given DMT function. As a specific example, we analyze the two-layer diagonal Bell Labs space-time architecture (D-BLAST) with a group zero-forcing receiver, the vertical BLAST (V-BLAST) with a minimum mean-square error receiver, and orthogonal space-time block codes (OSTBCs), and prove the monotonic behavior of the crossover point for those codes. Based on that, with respect to D-BLAST, V-BLAST, and OSTBC, we derive a method for the optimal space-time coding of a sequence that contains numerous progressive packets. We show that by employing the optimization method rather than exhaustive search, the computational complexity involved with optimal space-time coding can be exponentially reduced without losing any peak SNR performance.