新型船舶自动识别系统设计及其同步算法分析

为了提高船舶自动识别系统（AIS）的容量，提出了基于正交频分复用技术（OFDM）的新型AIS系统设计方案。新系统设计主要包括系统参数设计、系统帧结构设计。新系统链路容量和信道传输速率均较传统AIS系统提高了6倍，实现了频域资源的有效利用。该系统对符号定时偏差和载波频率偏差特别敏感，因此对接收信号的同步处理必不可少，在设计的新系统基础之上提出了一种新的盲估计算法，利用包含在循环前缀内的冗余信息，在多径信道信息未知的情况下，直接通过对接收信号做相关构造一个归一化的相关特性函数，通过此函数可得到符号时延位置和多径信道长度，进而得到载波频率偏差。仿真结果表明在多径信道下该算法也具有较好的性能。

Design of a novel automatic identification system and analysis of its synchronization algorithm

In order to improve the capacity of Automatic Identification System(AIS),a novel AIS design scheme is presented in which Orthogonal Frequency Division Multiplexing(OFDM) is adopted as the signal modulation mode. The design of the novel system includes system parameter design and frame structure design. The novel system makes full use of the spectrum resources and the link capacity and the transmission rate improve 6 times.OFDM system is particularly sensitive to the Symbol Timing Offset(STO) and Carrier Frequency Offset(CFO),so it is necessary to synchronize the received signal. A new blind symbol timing and frequency offset estimation algorithm is proposed which constructs a normalized correlation function between the received signals in multi-path fading channels. The proposed method gets the timing offset and the channel length from the correlation characteristics of the function directly.Consequently,the frequency offset is jointly estimated. The simulation results show that the algorithm has better performance even in multi-path channel.