System and method for transmitting and receiving single-carrier OQAM symbols with non-nyquist transmit pulse shaping
A system and method are provided for processing symbols for transmission. A set of 2K outputs is produced that includes K real components and K imaginary components from K complex symbols. A Fourier transform operation on the 2K outputs produces 2K Fourier transform outputs. Transmit pulse shaping is applied to the 2K Fourier transform outputs. The transmit pulse shape may be Nyquist or non-Nyquist. An inverse Fourier transform operation on the J pulse shaped outputs produces an inverse Fourier transform output. In the receiver, equalization is performed to remove the effect of both the channel and the transmit pulse shape. Nyquist pulse shaping is performed by applying a Nyquist pulse shape prior to converting back to time domain. The approach avoids self-interference, even in situations where the transmit pulse shape is non-Nyquist. The transmitter is free to select a pulse shape to optimize PAPR without being concerned with interference.
1. A communication method comprising:
producing a set of 2K outputs that include K real components and K imaginary components from K complex symbols;
performing a Fourier transform operation on the 2K outputs to produce 2K Fourier transform outputs;
pulse shaping the 2K Fourier transform outputs by multiplying each of J of the 2K Fourier transform outputs with a respective one of J non-zero coefficients, wherein the J non-zero coefficients represent a frequency response of a transmit pulse shape of a set of transmit pulse shapes, to produce J pulse shaped outputs, where K≤J<2K for odd K, and K+1≤J<2K for even K;
performing an inverse Fourier transform operation on the J pulse shaped outputs to produce an inverse Fourier transform output;
outputting the inverse Fourier transform output; and
transmitting signalling conveying J and K; wherein the signaling comprises an index of a value of J from within a set of possible values; or an index of a value of K/J from within a set of possible values of K/J.
2. The method of claim 1 further comprising
selecting the transmit pulse shape from the set of transmit pulse shapes, wherein the set of transmit pulse shapes includes at least one non-Nyquist pulse shape.
3. The method of claim 1 further comprising:
selecting a value of J based on a target spectral efficiency vs. peak average power ratio (PAPR) trade-off.
4. The method of claim 2 further comprising:
selecting the transmit pulse shape with the objective of minimizing peak average power ratio (PAPR) as among the set of transmit pulse shapes for a given value of J and a given transmit constellation or modulation order.
5. The method of claim 2 , further comprising selecting the transmit pulse shape with the objective of minimizing out of band emissions as among the set of transmit pulse shapes for a given value of J and a given transmit constellation or modulation order.
6. The method of claim 4 wherein the set of transmit pulse shapes includes:
raised root cosine (RRC), raised cosine (RC), Gaussian, Welch and Kaiser pulse shapes.
7. An apparatus comprising:
a processor and memory configured to perform the following steps:
producing a set of 2K outputs that include K real components and K imaginary components from K complex symbols;
performing a Fourier transform operation on the 2K outputs to produce 2K Fourier transform outputs;
pulse shaping the 2K Fourier transform outputs by multiplying each of J of the 2K Fourier transform outputs with a respective one of J non-zero coefficients, wherein the J non-zero coefficients represent a frequency response of a transmit pulse shape of a set of transmit pulse shapes, to produce J pulse shaped outputs, where K≤J<2K for odd K, and K+1≤J<2K for even K;
performing an inverse Fourier transform operation on the J pulse shaped outputs to produce an inverse Fourier transform output;
outputting the inverse Fourier transform output; and
transmitting signalling conveying J and K; wherein the signaling comprises an index of a value of J from within a set of possible values; or an index of a value of K/J from within a set of possible values of K/J.
8. The apparatus of claim 7 wherein the processor and memory configured to select the transmit pulse shape from the set of transmit pulse shapes, wherein the set of transmit pulse shapes includes at least one non-Nyquist pulse shape.
9. The apparatus of claim 7 wherein the processor and memory are further configured to perform the following:
selecting a value of J based on a target spectral efficiency vs. PAPR trade-off.
10. The apparatus of claim 7 wherein the processor and memory are further configured to select the transmit pulse shape with the objective of minimizing peak average power ratio (PAPR) as among the set of transmit pulse shapes for a given value of J and a given transmit constellation or modulation order.
11. The apparatus of claim 7 wherein the processor and memory are further configured to selects the transmit pulse shape with the objective of minimizing out of band emissions as among the set of transmit pulse shapes for a given value of J and a given transmit constellation or modulation order.
12. The apparatus of claim 7 wherein the set of transmit pulse shapes includes:
raised root cosine (RRC), raised cosine (RC), Gaussian, Welch and Kaiser pulse shapes.