副载波
频率偏移
偏移量(计算机科学)
发射机
计算机科学
本振子
算法
载波频率偏移
正交频分复用
无线电频率
电信
频道(广播)
程序设计语言
作者
Ryan Ramdial,Xiaojun Liang,Shiva Kumar,John D. Downie,William A. Wood
摘要
We introduce a new technique for obtaining the frequency offset introduced at the receiver due to the heterodyning of the transmitter laser and the local oscillator. This technique is needed for multi-subcarrier systems, as the offset must be removed without knowledge of the modulation format, making well-known algorithms that correct using it impractical. By detecting the spectral edges for the transmitted and received signals, it is possible to get a coarse estimate of the intermediate frequency by finding the difference between these two values. We then use this approximation as a starting point to fine search for the true value, by taking a window of possible values around the approximation. By taking the cross-correlation between the received data and a subset of the transmitted data for the subcarriers, we can verify whether the correct value is chosen, and if not, move on to the next estimate.
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