Transmitter using pi/2-pulse amplitude modulation symbol and spectrum shaping

A discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM) transmission method performed by a DFT-spread OFDM transmitter, the DFT-spread OFDM transmission method comprising:

• generating a pi/2 pulse amplitude modulation (PAM) symbol vector d by phase-shifting a symbol vector b including M PAM symbols;
• generating a DFT-spread pi/2 PAM symbol vector c by spreading the pi/2 PAM symbol vector d by using an M-point DFT matrix WM;
• generating a frequency domain spectrum shaped pi/2 PAM symbol vector a by multiplying each element of the DFT-spread pi/2 PAM symbol vector c by each element of a first shaping vector sT including one or more zero (0) elements;
• and
• allocating a non-zero element in the frequency domain spectrum shaped pi/2 PAM symbol vector a to a sub-carrier in an allocated frequency range.

A discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM) receiver comprising:

• a frequency domain receive signal generator configured to generate a vector {tilde over (y)} with cyclic prefix (CP) removed therefrom by receiving a signal y which has passed through a channel and removing the CP from the signal y, and generate a frequency domain receive vector by performing N-point DFT on the vector {tilde over (y)} with CP removed therefrom;
• a sub-carrier selection and zero padding module configured to generate a vector â having a length of M by generating and zero-padding a vector ã which selects parts corresponding to L sub-carriers in an allocated frequency range from among the frequency domain receive vector;
• a frequency domain receive spectrum shaper configured to generate a frequency domain receive spectrum shaped vector ĉ having a length of M by performing Hadamard product of the zero-padded vector â and a conjugate complex vector of a receive shaping vector sR;
• an inverse DFT (IDFT) module configured to generate a de-spread vector {circumflex over (d)} by multiplying the frequency domain receive spectrum shaped vector ĉ by a transverse DFT matrix
• W
• M
• H
• ,
• an inverse phase shifter configured to generate an inverse-phase-shifted vector {tilde over (b)} by multiplying the de-spread vector {circumflex over (d)} by a transverse phase shift matrix FH;
• and
• an imaginary part eliminator configured to generate an estimated value {circumflex over (b)} of a transmitted PAM symbol vector by taking real parts of the inverse-phase-shifted vector {tilde over (b)}.

A discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM) reception method performed by a DFT-spread OFDM receiver, the DFT-spread OFDM reception method comprising:

• generating a vector {tilde over (y)} with cyclic prefix (CP) removed therefrom by receiving a signal y which has passed through a channel and removing the CP from the signal y, and generating a frequency domain receive vector by performing N-point DFT on the vector {tilde over (y)} with CP removed therefrom;
• generating â vector a having a length of M by generating and zero-padding ã vector which selects parts corresponding to L sub-carriers in an allocated frequency range from among the frequency domain receive vector;
• generating a frequency domain receive spectrum shaped vector ĉ having a length of M by performing Hadamard product of the zero-padded vector â and a conjugate complex vector of a receive shaping vector sR;
• generating a de-spread vector {circumflex over (d)} by multiplying the frequency domain receive spectrum shaped vector ĉ by a transverse DFT matrix
• W
• M
• H
• ;
• generating an inverse-phase-shifted vector {tilde over (b)} by multiplying the de-spread vector {circumflex over (d)} by a transverse phase shift matrix;
• and
• generating an estimated value {circumflex over (b)} of a transmitted PAM symbol vector by taking real parts of the inverse-phase-shifted vector {tilde over (b)}.