TDD-LTE 系统中对抗整数倍频偏的小区初始搜索算法

The Anti-Integer-Frequency-Offset Initial Cell Search Algorithm in TDD-LTE Systems

摘要: ：LTE(Long Term Evolution，长期演进)系统中的小区初始搜索过程通过分别检测主同步信号 (Primary Synchronization Signal，PSS)和辅同步信号(Secondary Synchronization Signal，SSS)来完成，搜索结果包括小区组ID ?1?ID N 、符号定时、频偏估计、组内小区ID ?2?ID N 以及帧定时[1]。然而，若接收信号中存在整数倍频偏，则由于时域的相位旋转，主同步信号将很难用传统的相关算法检测到。提出一种主同步信号与整数倍频偏联合检测的方法，即使存在整数倍频偏，也能得到正确的符号定时。辅同步信号采用的是非相干的差分相关检测[2]，仿真表明，与传统的匹配滤波算法相比，可以有效的对抗信道时延扩展和载波频偏，适用于高速场景下时分双工(Time Division Duplex，TDD)LTE 系统的同步。

Abstract: In LTE systems, the initial cell search process is completed by detecting the primary synchronization signal and the secondary synchronization signal. The searching results include cell ID group, symbol timing, frequency offset estimation, intra group cell ID and frame timing[1]. However, if integer frequency offset presents in the received signal, due to time-domain phase rotation, the primary synchronization signal will be difficult to detected using the conventional correlation algorithm. A new joint detection method for integer frequency offset and primary synchronization signal is proposed, which can get the correct symbol timing even if the presence of integer frequency offset. Secondary synchronization signal is processed using the differential non-coherent correlation detection method[2]. Simulations show that compared with the traditional matched filtering algorithms, it can effectively combat the channel delay spread and carrier frequency offset and especially suitable for the high-speed scenarios in synchronization of time division duplex LTE systems.