This paper proposes a new scheme, that is, a constant is added to the real part or imaginary part of the signal at the transmitting end, and the constant becomes a pilot at the location of DC component, thereby replacing the scheme of traditional manual bias IQ modulator to generate a pilot. By adopting this scheme, the purpose of frequency offset estimation can be achieved, and the performance can be improved by quantitatively optimizing the magnitude of the constant at the same time. Using this technology and combined probability shaping technology, a 3.4Gbaud 256QAM OFDM signal can be transmitted 700 m wireless distance, achieving the normalized general mutual information (NGMI) threshold of 0.83 with 25 soft-decision forward-error correction (SD-FEC) overhead.
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