求翻译：基带OFDM系统的相关内容，有关背景和光纤通信发展的历史对OFDM 的一些关键技术，以及以后的发展方向。由介绍可知 OFDM 技术有许多其他调制技术没有的优点，但主要缺点就是存在高 PAPR 问题，这就大大影响了 OFDM 技术在实际应用中的推广，分析 OFDM 技术中的各个重要关键技术。是什么意思？

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Baseband OFDM system related content, related background and optical fiber communications development history to OFDM some key technologies, as well as later development direction.May know the OFDM technology by the introduction to have many other modulating technology modulating technique no merit,

Base-band OFDM system for related content, the background and history of the development of optical fiber communication on some key techniques of OFDM and future development directions. By introducing OFDM modulation techniques technology has many other advantages that are not, but the main drawback

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