WLC21-1: Improved High-rate Space-Time-Frequency Block Codes

High-rate space-time-frequency block codes (STFBC) are promising for achieving high bandwidth efficiency, low overhead and latency. Recently, a class of low-complexity STFBC methods based on two stages of complex diversity coding (CDC) have been proposed, known as double linear dispersion STFC(DLD-STFC). This paper investigates two issues related to the performance improvement of high-rate STFCs. First, it is shown that the two CDC stages of DLD-STFC can be interchanged. Two new diversity concepts for analysis of 3-dimensional DLD-STFC are introduced: per dimension diversity order and per dimension symbol-wise diversity order. A sufficient condition for DLD-STFC to achieve full symbol-wise diversity order is provided despite the existence of two CDC stages. Second, the gain obtainable in combining CDC with forward error correction (FEC) for STFC designs is quantified. Through simulations, it is shown that STFC based on the proper combination of CDC and FEC may outperform a variety of other STFC combinations, especially in spatially correlated channels. Further, the choice of the mapping from FEC to DLD-STFC may significantly impact system performance.