Simulations of iterative code-aided synchronization based on the sum-product algorithm framework

The estimation of unknown synchronization parameters is necessary for optimal receiver performance. Some important parameters include the carrier phase offset, the timing offset, and the carrier frequency offset. A generalized theoretical framework for maximum-likelihood (ML) parameter estimation using the iterative sum-product (SP) algorithm was previously proposed. Various algorithms such as the expectation-maximization (EM) algorithm and the steepest-descent (SD) algorithm were used in combination with the SP algorithm. Under some conditions, the SP synchronizer is shown to perform efficient joint estimation of three unknown parameters: carrier phase offset, timing offset, and carrier frequency offset.;The effectiveness of the SP-EM and SP-SD algorithms is determined by mean-squared error, bit-error rate, and frame-error rate results obtained from simulations. The effect of initial estimator accuracy on the convergence points of the SP synchronization algorithm is examined. The trade-off between error performance and computational complexity of the SP algorithm framework is discussed.