Timing synchronization and frequency offset estimation for Ultra-Wideband (UWB) Multi-Band OFDM systems

Abstract:
An algorithm based on distinguishing the first significant multipath (FTA) is proposed to address the critical issue of symbol timing synchronization and carrier frequency offset estimation in Ultra wideband (UWB) Multi-band OFDM (MB-OFDM) systems. FTA pinpoints the frame synchronization sequence and the start of its Fast Fourier Transform (FFT) window by accumulating multipath energies and then discerning for first significant multipath component through threshold comparison between consecutive accumulated energy samples. Thereafter, the frequency offset (FO) is estimated from phase differences between training symbols. Two channel models (CM), as proposed by IEEE 802.15 Channel Modeling sub-committee, CM1: line-of-sight for 0-4m and CM2: non-line-of-sight for 0-4m are simulated with 100,000 noisy realizations per threshold. The timing offset mean-squared errors for CM1 is 0.371 OFDM samples and CM2 is 4.548 OFDM samples under a typical signal-to-noise ratio (SNR) of 17 dB for high data rate applications. These are orders of magnitude lower compared to conventional OFDM-extended correlation methods. A maximum likelihood FO estimation algorithm is derived and its performance is compared with FTA simulation results. Variance of the FTA FO estimate approaches that of maximum likelihood FO estimate with a SNR loss of less than 0.5 dB.