Full diversity block diagonal codes for differential space-time-frequency coded OFDM

Focusing on orthogonal frequency division multiplexing (OFDM) transmissions over frequency selective Rayleigh fading channels, we consider full diversity block diagonal codes for differential space-time-frequency (DSTF) coded OFDM with no channel state information (CSI). Resorting to subcarrier grouping, we convert the system into a set of DSTF systems, within which DSTF coding is considered. Through pairwise error probability (PEP) analysis, the code design criteria are derived over correlated channels and shown to be not dependent on the channel correlations. In [Q. Ma, et al. (2003)], it is proved that full diversity gain can be achieved by appropriately using the existing unitary diagonal space-time (ST) codes without CSI over the frequency selective channels. We show here that, at higher data rates there exist fuller nondiagonal matrices that have the necessary unitary and full diversity properties, and outperform the diagonal codes in [Q. Ma, et al., (2003)], Two design methods are proposed for block diagonal codes with full diversity which are based on existing designs for flat fading channels.