Iterative joint detection, decoding, and synchronization with a focus on frame timing

The concept of an iterative receiver has gained attention as a means of performing reliable synchronization, especially at the low signal-to-noise ratios enabled by error correction codes. In this paper, we consider joint detection of the information bits and estimation of the channel gain, carrier phase, symbol timing, frame timing, and noise power. Our particular focus is on the frame timing where we evaluate the complexity of the iterative receiver by characterizing the frame offset distribution. A method for dynamically choosing the set of frame offsets processed by the iterative receiver is presented. The receiver utilizes the expectation-maximization algorithm to perform estimation and the sum-product algorithm to perform soft demodulation and decoding. Numerical results are presented to characterize the frame offset distribution and to demonstrate the receiver´s performance.