### Frame synchronization and symbol timing synchronization based on soft decision feedback in burst communication

YOU Xingyuan1，2, YANG Ping2, PENG Junwei1，2

1. 1.College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China
2.Wuhan Maritime Communication Research Institute, Wuhan 430079, China
• Online:2018-03-01 Published:2018-03-13

### 基于软判决反馈的猝发通信同步算法

1. 1.哈尔滨工程大学 信息与通信工程学院，哈尔滨 150001
2.武汉船舶通信研究所，武汉 430079

Abstract: To tackle the issues of frame synchronization and symbol timing synchronization in wireless burst communication system, a novel synchronization method based on soft decision feedback in fading channel is proposed. Firstly, this paper samples time-based sliding windows to obtain the received sequence of the preamble and data symbols, so the signal-to-noise ratio and fading are estimated on the received preamble sequence. Then a new likelihood function is proposed by using the soft decisions on the unknown PSK or QAM data symbols, and the new likelihood value is calculated by the received signal. Frame synchronization completed when the likelihood value exceeds the synchronization threshold. Finally, after a peak seeking to the likelihood function, a fine synchronization is implemented using the Gaussian interpolation. When conducted on the frame of 80 symbols within 16 symbols preamble, the simulation results demonstrate that, for unknown PSK symbols, the proposed method outperforms the Cramer-Rao Bound（CRB（16）） with the length of 16 known symbols at low SNR and approaches CRB（80） at high SNR. For unknown QAM symbols, the proposed method outperforms CRB（16） at both low SNR and high SNR.