คนข้างคุณจีบเพื่อนฉัน

คนข้างคุณจีบเพื่อนฉัน

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The person next to you flirted with my friend.

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my friend

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OFDM is a multi-carrier modulation [2] technology, which converts a serial high-rate data stream into many parallel low-rate data streams, modulates the low-rate data streams on orthogonal subcarriers, and then superimposes all subcarriers to form a transmission signal. Compared with the traditional single-carrier system, OFDM system has a higher spectrum utilization ratio because of the overlapping frequency spectrum of each subcarrier channel, and its spectrum efficiency is nearly twice as high as that of single carrier. At the same time, OFDM technology makes the high-rate data stream become a plurality of low-rate data streams transmitted in parallel on sub-carriers through serial/parallel conversion, which reduces the impact of wireless channel on the system and enhances the ability to resist multipath effect. In addition, orthogonal subcarriers of OFDM equate frequency selective fading channels with several parallel flat fading channels, and the influence of channels is equivalent to complex factors, which simplifies channel equalization. OFDM can also achieve the best performance through dynamic power allocation technology and bit adaptive modulation technology. Therefore, OFDM, as an efficient transmission technology, has attracted much attention, and has gradually become the key technology of many standards, such as digital audio broadcasting DAB, digital video broadcasting DVB, wireless local area network, digital television DTV and the fourth generation mobile communication.后点击翻译按钮