適用於OFDM無線通訊系統的同步信號偵測方法

An Efficient Synchronization Signal Detection Method for OFDM Communication System

李建民(Chien-Min Lee)

《電腦與通訊》 122期 (2007/12) Pp. 89-95

https://doi.org/10.29917/CCLTJ.200712.0013

摘要

OFDM系統中時序同步的方法通常是利用一組在時間域具有重複傳送特性的同步信號來做自相關性估測，但由於估測時會因為CP(Cyclic Prefix)信號或者是因為同步信號於時間域有過多的重複特性，使估測所得之峰值具有重複的現象，因而產生類似平原的樣貌，增加了檢測時的不確定性。再加上若接收機受通道、雜訊及移動速度等環境因素的影響時，同步信號的相關性將大幅降低，進而增加了估測的困難度。本文提出一複雜度低且具高辨識度之同步信號偵測方法，此種偵測方法可提高接收機於高干擾環境時的同步能力。

關鍵字

正交分頻多工 ； 時序同步 ； 同步信號

並列摘要

In an orthogonal frequency division multiplexing (OFDM) system, timing synchronization at the receiver is an important procedure that must be performed. Traditionally, the synchronization signal should be defined by character of repetition in time domain. Therefore, the well known auto-correlator can be employed as a timing detector at receiver. However, the plateau region will occur in the timing metric; its occurring time corresponds to the edge of OFDM symbol. This phenomenon may be generated by the cyclic prefix (CP) which append in front of OFDM symbol or the symbol generated by at least twice repetitions. An efficient timing offset estimation method for OFDM system will be proposed in this document. The uncertainty of plateau region can be eliminated by appending a simple circuit after the auto-correlator.

並列關鍵字

Orthogonal Frequency-Division Multiplexing ； OFDM ； Timing Synchronization ； Synchronization signal