Methods, apparatuses and systems directed to unique word discrete Fourier transform spread and shaped orthogonal frequency division multiplexing based transmissions

1. A method implemented in a transmitter comprising:

transforming a set of data symbols and a unique word (UW) sequence into a frequency domain (“f DOM ”) signal using a discrete Fourier transform (DFT);

replicating the f DOM signal so as to form a plurality of f DOM signal instances, wherein the plurality of f DOM signal instances is inclusive of the f DOM signal;

shaping each of the plurality of f DOM signal instances using one or more of a plurality of coefficients at least in part to suppress time domain samples that contribute to inter-symbol interference, wherein the plurality of coefficients are determined based on a time domain filter and correspond to a frequency response of the time domain filter, and wherein the time domain filter has a length that is less than or equal to a number of time domain samples that corresponds to an internal guard interval including the UW sequence;

combining the plurality of shaped f DOM signal instances to form a combined f DOM signal;

transforming the combined f DOM signal into a block-based signal using an inverse DFT (IDFT); and

transmitting the block-based signal.

2. The method of claim 1 , wherein the combined f DOM signal is mapped to a set of subcarriers.

3. The method of claim 1 , wherein the combined f DOM signal is mapped to a set of subcarriers, and wherein combining the plurality of shaped f DOM signal instances to form a combined f DOM signal comprises mapping the plurality of shaped f DOM signal instances to a respective plurality of subsets of the set of subcarriers.

4. The method of claim 3 , wherein at least one of the subsets of the plurality of subsets is not mutually exclusive from at least one other subset of the plurality of subsets.

5. The method of claim 2 , wherein combining the plurality of shaped f DOM signal instances to form a combined f DOM signal comprises mapping the plurality of shaped f DOM signal instances to a respective plurality of adjacent, non-overlapping subsets.

6. The method of claim 1 , wherein the DFT and the IDFT have respective sizes, wherein the size of the IDFT (IDFT size) is larger than the size of the DFT (DFT size), wherein the plurality of f DOM signal instances comprises a number, k, of f DOM signal instances, and wherein the number, k, corresponds to a ratio of the IDFT size to the DFT size.

7. The method of claim 1 , wherein shaping each of the plurality of f DOM signal instances using one or more of a plurality of coefficients comprises:

performing frequency-domain windowing on the plurality of f DOM signal instances.

8. The method of claim 1 , wherein the plurality of coefficients comprises a plurality of sets of coefficients, wherein the plurality of sets of coefficients corresponds to the plurality of f DOM signal instances, respectively, wherein the plurality of f DOM signal instances corresponds to a respective plurality of sets of subcarriers, and wherein shaping each of the plurality of f DOM signal instances comprises applying the plurality of sets of coefficients to the plurality of f DOM signal instances, respectively.

9. The method of claim 8 , wherein the plurality of sets of coefficients are rotated with a respective plurality of complex coefficients.

10. The method of claim 7 , wherein the performing frequency domain windowing comprises:

multiplying the plurality of f DOM signal instances with the plurality of coefficients, wherein the frequency response of the time domain filter suppresses one or more samples of one or more of the plurality of f DOM signal instances.

11. The method of claim 1 , wherein the internal guard interval is based on an up-sampling factor, and wherein the up-sampling factor corresponds to a ratio of the IDFT size to the DFT size.

12. The method of claim 7 , wherein the performing frequency domain windowing comprises:

multiplying the plurality of f DOM signal instances with the plurality of coefficients, wherein the time domain filter has sidelobes smaller than a Dirichlet sinc function.

13. A transmitter comprising: a discrete Fourier transform (DFT) unit; a processing unit; and an inverse DFT (IDFT) unit, wherein:

the DFT unit is configured to transform a set of data symbols and a unique word (UW) sequence into a frequency domain (“f DOM ”) signal using a DFT;

the processing unit is configured to:

replicate the f DOM signal so as to form a plurality of f DOM signal instances, wherein the plurality of f DOM signal instances is inclusive of the f DOM signal;

shape each of the plurality of f DOM signal instances using one or more of a plurality of coefficients at least in part to suppress time domain samples that contribute to inter-symbol interference, wherein the plurality of coefficients are determined based on a time domain filter and correspond to a frequency response of the time domain filter, and wherein the time domain filter has a length that is less than or equal to a number of time domain samples that corresponds to an internal guard interval including the UW sequence;

combine the plurality of shaped f DOM signal instances to form a combined f DOM signal; and

the IDFT unit is configured to:

transform the combined f DOM signal into a block-based signal using an IDFT; and

the transmitter is further configured to:

transmit the block-based signal.

14. The transmitter of claim 13 , wherein the processing unit is configured to shape each of the plurality of f DOM signal instances using one or more of a plurality of coefficients, at least in part, by:

performing frequency-domain windowing on the plurality of f DOM signal instances.

15. The transmitter of claim 14 , wherein the processing unit is configured to perform the frequency domain windowing, at least in part, by:

multiplying the plurality of f DOM signal instances with the plurality of coefficients, wherein the frequency response of the time domain filter suppresses one or more samples of one or more of the plurality of f DOM signal instances.

16. A method implemented in a transmitter comprising:

transforming a first set of data symbols and a first unique word (UW) sequence into a first frequency domain (“f DOM ”) signal using a first discrete Fourier transform (DFT);

replicating the first f DOM signal so as to form a plurality of first f DOM signal instances, wherein the plurality of first f DOM signal instances is inclusive of the first f DOM signal;

shaping each of the plurality of first f DOM signal instances using one or more of a first plurality of coefficients at least in part to suppress first time domain samples that contribute to a first inter-symbol interference, wherein the first plurality of coefficients are determined based on a first time domain filter and correspond to a first frequency response of the first time domain filter, and wherein the first time domain filter has a length that is less than or equal to a first number of time domain samples that corresponds to a first internal guard interval including the first UW sequence;

combining the plurality of shaped first f DOM signal instances to form a first combined f DOM signal;

transforming a second set of data symbols and a second UW sequence into a second f DOM signal using a second DFT;

replicating the second f DOM signal so as to form a plurality of second f DOM signal instances, wherein the plurality of second f DOM signal instances is inclusive of the second f DOM signal;

shaping each of the plurality of second f DOM signal instances using one or more of a second plurality of coefficients at least in part to suppress second time domain samples that contribute to a second inter-symbol interference, wherein the second plurality of coefficients are determined based on a second time domain filter and correspond to a second frequency response of the second time domain filter, and wherein the second time domain filter has a length that is less than or equal to a second number of time domain samples that corresponds to a second internal guard interval including the second UW sequence;

combining the plurality of shaped second f DOM signal instances to form a second combined f DOM signal;

adding the first combined f DOM signal and the second combined f DOM signal to form a third f DOM signal;

transforming the third f DOM signal into a block-based signal using an inverse DFT (IDFT); and

transmitting the block-based signal.

17. The method of claim 16 , wherein the third f DOM signal is mapped to a set of subcarriers, and wherein at least one of:

(a) combining the plurality of shaped first f DOM signal instances to form a first combined f DOM signal comprises mapping the plurality of shaped first f DOM signal instances to the set of subcarriers; and

combining the plurality of shaped second f DOM signal instances to form a second combined f DOM signal comprises mapping the plurality of shaped second f DOM signal instances to the set of subcarriers;

(b) a sample of the first combined f DOM signal is mapped to a subcarrier of the set of subcarriers;

a sample of the second combined f DOM signal is mapped the same subcarrier of the set of subcarriers; and

adding the first combined f DOM signal and the second combined f DOM signal to form a third f DOM signal comprises adding the sample of the first combined f DOM signal and the sample of the second combined f DOM signal;

(c) combining the plurality of shaped first f DOM signal instances to form a first combined f DOM signal comprises mapping the plurality of shaped first f DOM signal instances to a first partition of the set of subcarriers; and

combining the plurality of shaped second f DOM signal instances to form a second combined f DOM signal comprises mapping the plurality of shaped second f DOM signal instances to a second partition of the set of subcarriers;

(d) combining the plurality of shaped first f DOM signal instances to form a first combined f DOM signal comprises mapping the plurality of shaped first f DOM signal instances to a first subset of the set of subcarriers; and

combining the plurality of shaped second f DOM signal instances to form a second combined f DOM signal comprises mapping the plurality of shaped second f DOM signal instances to a second subset of the set of subcarriers, wherein the first and second subsets have one or more subcarriers in common; or

(e) the plurality of first f DOM signal instances are mapped to a first subset of the set of subcarriers;

the plurality of second f DOM signal instances are mapped to a second subset of the set of subcarriers;

the first and second subsets have one or more subcarriers in common; and

adding the first combined f DOM signal and the second combined f DOM signal to form a third f DOM signal comprises:

adding one or more samples of the first combined f DOM signal and the second combined f DOM signal mapped to the one or more subcarriers in common; and

appending to the added samples: (i) one or more samples of the first combined f DOM signal mapped to subcarriers of the first subset other than the one or more subcarriers in common; and (ii) one or more samples of the second combined f DOM signal mapped to subcarriers of the second subset other than the one or more subcarriers in common.

18. The method of claim 16 , wherein:

adding the first combined f DOM signal and the second combined f DOM signal to form a third f DOM signal comprises concatenating the first combined f DOM signal and the second combined f DOM signal.

19. The method of claim 16 , wherein the first time domain filter is the same as the second time domain filter.

20. The transmitter of claim 13 , wherein the plurality of coefficients comprises a plurality of sets of coefficients, wherein the plurality of sets of coefficients corresponds to the plurality of f DOM signal instances, respectively, wherein the plurality of f DOM signal instances corresponds to a respective plurality of sets of subcarriers, and wherein the processing unit is configured to shape the plurality of f DOM signal instances, at least in part, by applying the plurality of sets of coefficients to the plurality of f DOM signal instances, respectively.

21. The transmitter of claim 20 , wherein the plurality of sets of coefficients are rotated with a respective plurality of complex coefficients.

22. The transmitter of claim 13 , wherein the internal guard interval is based on an up-sampling factor, and wherein the up-sampling factor corresponds to a ratio of the IDFT size to the DFT size.

23. The transmitter of claim 14 , wherein the processing unit is configured to perform the frequency domain windowing, at least in part, by:

multiplying the plurality of f DOM signal instances with the plurality of coefficients, wherein the time domain filter has sidelobes smaller than a Dirichlet sinc function.

24. The transmitter of claim 13 , wherein the combined f DOM signal is mapped to a set of subcarriers, and wherein combining the plurality of shaped f DOM signal instances to form a combined f DOM signal comprises mapping the plurality of shaped f DOM signal instances to a respective plurality of subsets of the set of subcarriers.

25. The transmitter of claim 13 , wherein the DFT and the IDFT have respective sizes, wherein the size of the IDFT (IDFT size) is larger than the size of the DFT (DFT size), wherein the plurality of f DOM signal instances comprises a number, k, of f DOM signal instances, and wherein the number, k, corresponds to a ratio of the IDFT size to the DFT size.