SIGNAL PROCESSING (TO APPEAR) A View on Full-Diversity Modulus-Preserving Rate-One Linear Space-Time Block Codes ∗

SIGNAL PROCESSING (TO APPEAR) 1 In this paper, we consider the class of linear space time block codes (STBCs) that possess the following properties: i) enabling full antenna diversity, ii) preserving the modulus of information symbols, and iii) achieving the maximum rate of one symbol per channel use under i) and ii). We first provide an alternative construction for full-diversity rate-one STBCs that are based on linear constellation precoding (LCP). In sharp contrast to existing LCP-based designs, the proposed construction is modulus-preserving, thanks to an explicit unitary diagonal precoding on symbol blocks combined with an implicit fast-Fouriertransform (FFT) precoding via circularly shifted transmissions over multiple antennas. Our proposed construction also allows flexible choices on the precoder size, a feature not available in the original design. We then demonstrate that quasi-orthogonal (QO) STBCs can be constructed by embedding moduluspreserving LCP designs into orthogonal structures. Interestingly, QO-STBCs can be interpreted as spacetime-frequency (STF) block codes, that were originally developed for multi-antenna multi-carrier systems, up to FFT transformations. Index Terms Space time block coding, linear constellation precoding, circular delay diversity, quasi-orthogonal, full antenna diversity, modulus-preserving. I