一种基于前导序列的OFDM信息调制技术

OFDM系统中的前导序列通常被设计用于接收端的定时同步和频偏估计，并不包含任何有效的比特信息。在前导序列中调制比特信息的设计方式一定程度上能够提升通信系统的频谱效率，并拓展了前导设计的功能。通过对CAZAC序列进行相位旋转和循环移位处理，提出了一种新的在前导序列设计中嵌入信息数据的方案。调制信息后的CAZAC序列仍具有恒包络特性和良好的周期自相关性，并设计了相应的时频同步算法和信息提取方法。相比已有方案，所提的前导设计方式在不影响定时同步和频偏估计性能的情况下，提高了信息承载能力。分析与仿真结果表明，对于相同长度的前导序列，所提方案在信息承载量和传输可靠性方面均优于现有方法，同时可以取得较好的定时同步与频偏估计性能。

An OFDM Information Modulation Technology Based on Preamble Sequence

? ?The preamble sequences in OFDM systems are usually designed for timing synchronization and frequency offset estimation， and do not contain any bits of information. Modulating the preamble sequence with extra information improves the spectral efficiency and expands its original functions. By cyclic shift and phase rotation of CAZAC sequence， a new scheme of embedding information bits in preamble sequence design is proposed. The modulated CAZAC sequence still has constant envelope and good periodic autocorrelation， and the corresponding time-frequency synchronization algorithm and information demodulation method are presented. Compared with the existing works， the proposed preamble design greatly improves the capability of bits carrying without deterioration of performances of timing synchronization and frequency offset estimation. The analysis and simulation results demonstrate that for the same length of preamble sequence， the proposed scheme is superior to the existing methods in terms of information carrying capacity and reliability， and achieves good timing synchronization and frequency offset estimation performance.