System and method for generating reference signal with low peak average power ratio
A reference signaling scheme is provided that is based on the use of a Zadoff Chu sequence with cyclic repetition, optionally code division multiplexing precoding, together with frequency domain spectral shaping (FDSS). A specific pulse shape design for the FDSS part of the reference signal scheme in some embodiments involves the use of a raised cosine pulse raised to the power of β. The new solution for generating reference signals has a Low peak average power ratio that matches the PAPR of SC-OQAM, good channel estimation performance, and the ability to implement CDM in the frequency domain to increase multiplexing gain.
1. A method comprising:
receiving, by an apparatus from a network device, a first signaling indicating a length K sequence;
transmitting, by the apparatus to the network device a reference signal;
wherein the reference signal is obtained from the length K sequence, and the length K sequence is obtained by a cyclicly repeated length p ZC sequence, where p is a prime number larger than K/2 and where p is also smaller than a largest prime number that is smaller than K,
wherein the reference signal is obtained from the length K sequence by:
applying, by the apparatus, pre-coding to the length K sequence to produce a pre-coded sequence;
generating, by the apparatus, a first pulse shaped frequency domain sequence by applying first frequency domain spectral shaping to the pre-coded sequence.
2. The method of claim 1 , wherein the first frequency domain spectral shaping is a preconfigured FDSS pulse shape or an FDSS pulse shape indicated in a second signalling from the network device.
3. The method of claim 1 , wherein the first pulse shaped frequency domain sequence is generated by applying a raised cosine pulse raised to a power of β≥0.5, or β=0.8.
4. The method of claim 1 , wherein applying pre-coding to the length K sequence to produce a pre-coded sequence comprises:
multiplying the length K sequence by an orthogonal cover code.
5. The method of claim 4 wherein the reference signal is obtained from the length K sequence by:
producing a mapped sequence by mapping the first pulse shaped frequency domain sequence to a first subset of a set of subcarriers.
6. The method of claim 5 wherein the orthogonal cover code is one of a set of orthogonal cover codes associated with the first subset of the set of subcarriers.
7. The method of claim 1 further comprising:
performing data signal generation comprising applying second frequency domain spectral shaping to produce a second pulse shaped frequency domain sequence.
8. The method of claim 7 wherein:
applying first frequency domain spectral shaping comprises applying a first pulse shape;
applying second frequency domain spectral shaping also comprises applying the first pulse shape or a second pulse shape that is different from the first pulse shape.
9. The method of claim 1 wherein p is a smallest prime number larger than K/2.
10. A method comprising:
transmitting, by a network device to an apparatus, a first signaling indicating a length K sequence;
receiving, by the network device from the apparatus a reference signal;
wherein the reference signal is obtained from the length K sequence, and the length K sequence is obtained by a cyclicly repeated length p ZC sequence, where p is a prime number larger than K/2 and where p is also smaller than a largest prime number that is smaller than K,
wherein the reference signal is obtained from the length K sequence by:
applying, by the apparatus, pre-coding to the length K sequence to produce a pre-coded sequence;
generating, by the apparatus, a first pulse shaped frequency domain sequence by applying first frequency domain spectral shaping to the pre-coded sequence.
11. The method of claim 10 , wherein the first frequency domain spectral shaping is performed by the apparatus using a first frequency domain spectral shaping pulse shape unknown to the network device, the method further comprising:
performing channel estimation to produce a channel estimate that includes the effect of the first frequency domain pulse shape.
12. The method of claim 10 , further comprising:
transmitting signalling to indicate a first frequency domain spectral shaping pulse shape to be used by the apparatus to generate the reference signal;
wherein the reference signal is based on a first frequency domain spectral shaping performed by the apparatus using the first frequency domain pulse shape known to the network device.
13. The method of claim 10 wherein p is a smallest prime number larger than K/2.
14. An apparatus comprising:
a processor and memory, the apparatus configured to:
receive, by the apparatus from a network device, a first signaling indicating a length K sequence;
transmit, by the apparatus to the network device a reference signal;
wherein the reference signal is obtained from the length K sequence, and the length K sequence is obtained by a cyclicly repeated length p ZC sequence, where p is a prime number larger than K/2 and where p is also smaller than a largest prime number that is smaller than K,
wherein the apparatus is configured to obtain the reference signal is obtained from the length K sequence by:
applying, by the apparatus, pre-coding to the length K sequence to produce a pre-coded sequence;
generating, by the apparatus, a first pulse shaped frequency domain sequence by applying first frequency domain spectral shaping to the pre-coded sequence.
15. The apparatus of claim 14 , wherein the first frequency domain spectral shaping is a preconfigured FDSS pulse shape or an FDSS pulse shape indicated in a second signalling from the network device.
16. The apparatus of claim 14 , the apparatus is configured to apply pre-coding to the length K sequence to produce a pre-coded sequence by:
multiplying the length K sequence by an orthogonal cover code.
17. The apparatus of claim 14 further configured to:
perform data signal generation comprising applying second frequency domain spectral shaping to produce a second pulse shaped frequency domain sequence.
18. The apparatus of claim 14 wherein p is a smallest prime number larger than K/2.
19. A network device comprising:
a processor and memory, the network device configured to:
transmit, by a network device to an apparatus, a first signaling indicating a length K sequence;
receive, by the network device from the apparatus a reference signal;
wherein the reference signal is obtained from the length K sequence, and the length K sequence is obtained by a cyclicly repeated length p ZC sequence, where p is a prime number larger than K/2 and where p is also smaller than a largest prime number that is smaller than K,
wherein the reference signal is obtained from the length K sequence by:
applying, by the apparatus, pre-coding to the length K sequence to produce a pre-coded sequence;
generating, by the apparatus, a first pulse shaped frequency domain sequence by applying first frequency domain spectral shaping to the pre-coded sequence.
20. The apparatus of claim 17 configured to apply the first frequency domain spectral shaping by applying a first pulse shape and to apply the second frequency domain spectral shaping by applying the first pulse shape or a second pulse shape different from the first pulse shape.
21. The network device of claim 19 , wherein the first frequency domain spectral shaping is performed by the apparatus using a first frequency domain spectral shaping pulse shape unknown to the network device, the network device further configured to:
perform channel estimation to produce a channel estimate that includes the effect of the first frequency domain pulse shape.
22. The network device of claim 19 , further configured to:
transmit signalling to indicate a first frequency domain spectral shaping pulse shape to be used by the apparatus to generate the reference signal;
wherein the reference signal is based on a first frequency domain spectral shaping performed by the apparatus using the first frequency domain pulse shape known to the network device,
the network device further configured to:
process the received reference signal by applying a frequency domain spectral shaping pulse shape corresponding to the first frequency domain pulse shape to remove the effect of the first frequency domain spectral shaping;
perform channel estimation based on an output of the frequency domain spectral shaping.
23. The network device of claim 19 wherein p is a smallest prime number larger than K/2.