Fano multiple-symbol differential detectors

Multiple-symbol differential detection (MSDD) is a robust maximum-likelihood receiver for frequency-nonselective fast Rayleigh fading channels. However, its complexity grows exponentially with the block size. Recently, multiple-symboldifferential sphere decoder (MSDSD) is developed to alleviate this problem but its complexity at low signal-to-noise ratio (SNR) grows exponentially. This work investigates the possibility of using a Fano decoder as an efficient MSDD. The detector, namely Fano-MSDD, is an "intelligent" decision-feedback detector (DFD) that uses a running threshold and an accumulated path metric as navigation tools when it roams the decoding tree. Our results indicate that Fano-MSDD is more attractive than DFD from the perspectives of error-performance and complexity. When compared to MSDSD, our best Fano-MSDD suffers a small degradation in power efficiency. However, its complexity is a stable function of SNR. Furthermore, with the extension of Fano-MSDD to differential space-time modulation, our receivers become more remarkable when compared to other reduced complexity techniques.