Method and system for generating a transmit waveform for reference sequences

1. A method for generating a waveform in a communication network, the method comprising:

selecting, by a user equipment (UE) transmitter, at least one sequence from a plurality of sequences based on an indication by a base station (BS) to a user equipment (UE), wherein:

said plurality of sequences comprises a plurality of sub-sets of sequences such that a sequence in a sub-set of sequences is a cyclic shifted version of another sequence in the said sub-set of sequences, and

each of the plurality of sequences is a Binary Phase Shift Keying (BPSK) sequence;

rotating, by the UE transmitter, successive samples of the at least one sequence from a plurality of sequences by 90 degrees to produce at least one rotated sequence;

transforming, by the UE transmitter, the at least one rotated sequence into frequency domain using a Discrete Fourier Transform (DFT) to generate a transformed sequence;

mapping, by the UE transmitter, the transformed sequence using a plurality of subcarriers to generate a mapped transformed sequence; and

processing, by UE transmitter, the mapped transformed sequence to generate a waveform having an optimized PAPR, optimized auto and cross-correlation.

2. The method as claimed in claim 1 , wherein each of the plurality of sequences is a demodulation reference sequence (DMRS).

3. The method as claimed in claim 1 , wherein the plurality of sequences has optimized auto, cross correlation and spectrum flatness.

4. The method as claimed in claim 1 , wherein:

for the sequence of length 12, the selected at least one sequence is one of:

000001001001,

001001000001, and

000001101110;

for the sequence of length 18, the selected at least one sequence is one of:

010011011000000010,

001001111000001100,

000000010010011011, and

000001100001001111; and

for the sequence of length 24, the selected at least one sequence is one of:

000000000111100010110001,

100010110001000000000111, and

000000111011000110001010.

5. The method as claimed in claim 1 , wherein the method comprises oversampling, by the UE transmitter, the transformed sequence by a factor of P to generate an oversampled transformed sequence, said oversampled transformed sequence has P zeros between any two consecutive samples of the transformed sequence, said P is an integer, and wherein the mapping is performed according to the oversampled transformed sequence.

6. The method as claimed in claim 1 , wherein the method comprises an optional precoding of the at least one rotated sequence using a precoder to produce a precoded sequence which is transformed into frequency domain using a DFT operation to generate a transformed sequence.

7. The method as claimed in claim 6 , wherein the precoder is of one of a 1+D precoder and a 1−D precoder, wherein D is a delay unit.

8. The method as claimed in claim 1 , wherein the method comprises an optional filtering of using a filter to produce a filtered sequence prior to the mapping.

9. The method as claimed in claim 8 , wherein the filter is a DFT of one of a 1+D precoder and a 1−D precoder, wherein D is a delay unit.

10. The method as claimed in claim 8 , wherein the filtered sequence is mapped to a plurality of subcarriers using a mapping unit to generate a mapped filtered sequence, said mapped filtered sequence is processed using Inverse Discrete Fourier Transform (IDFT) by the UE transmitter to generate a waveform.

11. The method as claimed in claim 1 , wherein processing to generate a waveform comprises performing Inverse Discrete Fourier Transform (IDFT) on the mapped sequence to generate a waveform in time domain.

12. A user equipment (UE) transmitter for generating a waveform in a communication network, the UE comprising:

a processor; and

a memory communicatively coupled with the processor, wherein the processor is configured to:

select at least one sequence from a plurality of sequences based on an indication by a base station (BS) to a user equipment (UE), wherein:

said plurality of sequences comprises a plurality of sub-sets of sequences such that a sequence in a sub-set of sequences is a cyclic shifted version of another sequence in the said sub-set of sequences, and

each of the plurality of sequences is a Binary Phase Shift Keying (BPSK) sequence;

rotate successive samples of the at least one sequence from a plurality of sequences by 90 degrees to produce at least one rotated sequence;

transform the at least one rotated sequence into frequency domain using a Discrete Fourier Transform (DFT) to generate a transformed sequence;

map the transformed sequence using a plurality of subcarriers to generate a mapped transformed sequence; and

process the mapped transformed sequence to generate a waveform having an optimized PAPR, optimized auto and cross-correlation.

13. The UE transmitter as claimed in claim 12 , wherein each of the plurality of sequences generated is a demodulation reference sequence (DMRS).

14. The UE transmitter as claimed in claim 12 , wherein the plurality of sequences has optimized auto-correlation, cross correlation and spectrum flatness.

15. The UE transmitter as claimed in claim 12 , wherein the transmitter comprises an optional precoder for precoding the at least one rotated sequence to produce a precoded sequence.

16. The UE transmitter as claimed in claim 15 , wherein the precoder is of one of a 1+D precoder and a 1−D precoder, wherein D is a delay unit.

17. The UE transmitter as claimed in claim 12 , wherein the transmitter comprises an optional filter for filtering the transformed sequence to produce a filtered sequence.

18. The UE transmitter as claimed in claim 17 , wherein the filter is a DFT of one of a 1+D precoder and a 1−D precoder, wherein D is a delay unit.

19. The method as claimed in claim 17 , wherein the filtered sequence is mapped to a plurality of subcarriers using a mapping unit to generate a mapped filtered sequence, said mapped filtered sequence is processed to generate a waveform.

20. The UE transmitter as claimed in claim 12 , wherein the transmitter comprises an Inverse Discrete Fourier Transform (IDFT) to process the mapped transformed sequence to generate a waveform in time domain.