A Post-Detection SNR-Aided Timing Recovery Loop for MIMO-OFDM Receivers

In this paper, a novel third-order phase lock loop (PLL) is proposed for the timing recovery in MIMO-OFDM systems. It differentiates from conventional timing recovery algorithms for OFDM systems in two aspects. Firstly a new timing-clock-offset (TO) estimator is proposed, which utilizes the post MIMO detection SNRs to weight and combine TO estimates in frequency and spatial domains. This TO estimator efficiently handles the MIMO fading and the colored noise caused by MIMO detection to improve the estimation accuracy. Secondly, a novel third-order PLL structure is developed and its stochastic difference equation (SDE) that represents the dynamic behavior of the tracking loop is derived and used to evaluate the loop performance. The proposed PLL has an good loop noise performance for fast acquisition and stable tracking. The analysis and simulation show that the proposed timing recovery scheme outperforms the conventional timing recovery schemes in MIMO fading channel.