Coding Assisted Carrier Synchronization Algorithm Research

In communication systems, the synchronization of the receiver requires to accurately estimate a number of parameters such as the carrier frequency and phase offset. However, with the recent advent of powerful coding techniques, the conventional synchronization modes have been shown to be unable to properly synchronize state-of-the-art receivers. Recently, new family of synchronizers referred to as code-aided (CA) synchronizers is widely researched for they can work successfully at these receivers. The ideal behind CA synchronization is to use the soft information obtained from the Turbo decoder to improve the estimation quality. This dissertation focused on code-aided carrier synchronization algorithm.Following is the structure of this dissertation.In the first part, it has an overview of the development of the deep space and the researchment on the code-aided carrier synchronization. The purpose and the content of this dissertation are listed at last.In chapter 2, it describes the system model of the algorithm for carrier synchronization. Firstly introduce the general model of digital communication systems, and then make some introduction about the techniques of the digital modulation. Finally, analysis of the carrier phase offset impact on the system performance, and point out the importance of carrier synchronization.In chapter 3, we introduce the Turbo decoder, and focused on the design of a rate 1/6 SCCC(Serial concatenated convolutional codes).The fourth chapter describes several common carrier phase estimation algorithms including EM (expectation maximization), DDCS (decision directed carrier synchronization), and APPA (a priori probability aided). For each algorithm, we made a detailed introduction in theory, and give the simulation results.In chapter 5, firstly introduces the principle of frequency sweep, then gives two simply and feasibly sweep algorithm. after that gives an estimation algorithm which is suited to the condition under the residual carrier frequency offset, Finally, derives two carriers synchronization algorithms under the large carrier frequency offset, and gives the simulation results.In chapter 6, it introduces the algorithm of timing recovery and the carrier recovery algorithm in the application of high QAM modulation.