On the Performance Limits of Scalar Coding Over MISO Channels

The performance limits of scalar coding for multiple-input single-output channels are revisited in this work. By employing randomized beamforming, Narula et al. demonstrated that the loss of scalar coding is universally bounded by ∼ 2.51 dB (or 0.833 bits/symbol) for any number of antennas and channel gains. In this work, by using randomized beamforming in conjunction with space-time codes, it is shown that the bound can be tightened to ∼ 1.1 dB (or 0.39 bits/symbol). Index Terms Antenna arrays, capacity, diversity, MISO Gaussian channel, space-time coding, quasi-orthogonal space-time block codes.