A quasi-constant-amplitude scheme for orthogonal frequency-division multiplexing (OFDM) over wireless channels is proposed. To reduce the high peak-to-average power ratio (PAPR) of OFDM, a conventional scheme called constant envelope OFDM (CE-OFDM) transforms the OFDM signal into a phase modulated signal. Although CE-OFDM considerably increases an amount of computational complexity, the proposed scheme does not require such an amount of complexity and can suppress levels of out-of-band emission (OOBE) than CE-OFDM. The transmitter of the proposed scheme decomposes an OFDM signal into two constant-amplitude signals so as to reduce PAPR to the lowest level of 0 dB. Since the two signals cause high levels of OOBE, these signals are passed into a low-pass filter (LPF). The two LPF outputs, of which amplitudes are quasi-constant, are transmitted from the same transmit antenna at different timing. On the receiver side, two received signals that originate from the two LPF outputs and that propagate through a wireless channel are combined to regenerate the original OFDM signal. Computer simulation results demonstrate that the proposed scheme with a properly designed LPF is much superior to CE-OFDM in bit error rate (BER) performance while reducing OOBE to much lower levels. It is also shown that although LPF increases PAPR of the proposed scheme from 0 dB to about 2.5 dB, the PAPR is 8 dB lower than the conventional OFDM signal at the complementary cumulative distribution function of 0.001, which can verify the effectiveness of the proposed scheme.


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    Title :

    Quasi-Constant-Amplitude OFDM for Wireless Communication Systems


    Contributors:


    Publication date :

    2020-11-01


    Size :

    1129503 byte





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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