Reference signal generation method, reference signal detection method, and communications apparatus
This application provides a reference signal generation method in which a terminal device or a network device generates a reference signal by using a pseudo-random sequence initial factor c init provided in the embodiments of this application. Compared with a solution in the current technology, the reference signal generation method can support a relatively large quantity of reference signal sequences, to better meet the requirements of different 5G scenarios. The reference signal generation method may include obtaining a reference signal sequence based on a pseudo-random sequence initial factor c init , and mapping the sequence to one or more OFDM symbols. The pseudo-random sequence initial factor c init is related to a parameter d, d=max(log 2 (n ID,max +1)−10,0) or d=max(log 2 )(n ID,max +1)−12,0), max represents that a larger value is selected from two values, and n ID,max represents a maximum value of a reference signal sequence ID.
1. A reference signal generation method, comprising:
obtaining a reference signal sequence based on a pseudo-random sequence initial factor c init ; and
mapping the reference signal sequence to one or more orthogonal frequency-division multiplexing (OFDM) symbols,
wherein:
the pseudo-random sequence initial factor c init is represented by using 31 bits;
10 least significant bits in the 31 bits represent n ID mod 1024;
21 most significant bits in the 31 bits represent (N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1); and
d bits in the 21 most significant bits represent
⌊
n
I
D
1
0
2
4
⌋
,
and a value of d is related to a maximum value of n ID wherein:
N symb slot represents a quantity of OFDM symbols in a slot,
└ ┘ represents rounding down,
n s, f μ represents an index of a slot in a frame,
l represents an index of an OFDM symbol in a slot,
n ID represents a reference signal sequence ID,
μ represents a parameter related to a subcarrier spacing, and
mod represents a modulo operation.
2. The method according to claim 1 , wherein that c init is represented by using 31 bits comprises:
c init is obtained by first calculating a sum of n ID mod 1024 represented by using the 10 least significant bits, (N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1) represented by using the 21 most significant bits, and
⌊
n
I
D
1
0
2
4
⌋
represented by using the d bits, and then performing a modulo operation on the sum by using 2 31 .
3. The method according to claim 1 , wherein the d bits overlap the 21 most significant bits, and the d bits are located in the middle of the 21 most significant bits.
4. The method according to claim 1 , wherein when n ID is less than 4095, a value of d is 2.
5. The method according to claim 1 , wherein
the pseudo-random sequence initial factor c init satisfies the following formula:
C
init
=
[
2
31
-
d
⌊
n
ID
1024
⌋
+
(
2
10
(
N
symb
slot
n
s
,
f
μ
+
l
+
1
)
(
2
(
n
ID
mod
1024
)
+
1
)
+
(
n
ID
mod
1024
)
)
]
mod
2
31
.
6. A reference signal detection method, comprising:
receiving a reference signal, to obtain a first sequence;
obtaining a second sequence based on a pseudo-random sequence initial factor c init ; and
performing correlation detection on the first sequence and the second sequence, wherein
the pseudo-random sequence initial factor c init is represented by using 31 bits;
10 least significant bits in the 31 bits represent n ID mod 1024;
21 most significant bits in the 31 bits represent (N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1); and
d bits in the 21 most significant bits represent
⌊
n
I
D
1
0
2
4
⌋
,
and a value of d is related to a maximum value of n ID , wherein:
N symb slot represents a quantity of orthogonal frequency-division multiplexing (OFDM) symbols in a slot,
└ ┘ represents rounding down,
n s, f μ represents an index of a slot in a frame,
l represents an index of an OFDM symbol in a slot,
n ID represents a reference signal sequence ID,
μ represents a parameter related to a subcarrier spacing, and
mod represents a modulo operation.
7. The method according to claim 6 , wherein that c init is represented by using 31 bits comprises:
c init is obtained by first calculating a sum of n ID mod 1024 represented by using the 10 least significant bits,
(N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1) represented by using the 21 most significant bits, and
⌊
n
I
D
1
0
2
4
⌋
represented by using the d bits, and then performing a modulo operation on the sum by using 2 31 .
8. The method according to claim 6 , wherein the d bits overlap the 21 most significant bits, and the d bits are located in the middle of the 21 most significant bits.
9. The method according to claim 6 , wherein when n ID is less than 4095, a value of d is 2.
10. The method according to claim 6 , wherein the pseudo-random sequence initial factor c init satisfies the following formula:
C
init
=
[
2
31
-
d
⌊
n
ID
1024
⌋
+
(
2
10
(
N
symb
slot
n
s
,
f
μ
+
l
+
1
)
(
2
(
n
ID
mod
1024
)
+
1
)
+
(
n
ID
mod
1024
)
)
]
mod
2
31
.
11. A communications apparatus, comprising at least one processor and a memory coupled with the at least one processor, wherein the at least one processor is configured to:
obtain a reference signal sequence based on a pseudo-random sequence initial factor c init ; and
map the sequence to one or more orthogonal frequency-division multiplexing (OFDM) symbols,
and wherein:
the pseudo-random sequence initial factor c init is represented by using 31 bits;
10 least significant bits in the 31 bits represent n ID mod 1024;
21 most significant bits in the 31 bits represent (N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1); and
d bits in the 21 most significant bits represent
⌊
n
I
D
1
0
2
4
⌋
,
and a value of d is related to a maximum value of n ID , wherein:
N symb slot represents a quantity of OFDM symbols in a slot,
└ ┘ represents rounding down,
n s, f μ represents an index of a slot in a frame,
l represents an index of an OFDM symbol in a slot,
n ID represents a reference signal sequence ID,
μ represents a parameter related to a subcarrier spacing, and
mod represents a modulo operation.
12. The apparatus according to claim 11 , wherein that c init is represented by using 31 bits comprises:
c init is obtained by first calculating a sum of n ID mod 1024 represented by using the 10 least significant bits,
(N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1) represented by using the 21 most significant bits, and
⌊
n
I
D
1
0
2
4
⌋
represented by using the d bits, and then performing a modulo operation on the sum by using 2 31 .
13. The apparatus according to claim 11 , wherein the d bits overlap the 21 most significant bits, and the d bits are located in the middle of the 21 most significant bits.
14. The apparatus according to claim 11 , wherein when n ID is less than 4095, a value of d is 2.
15. The apparatus according to claim 11 , wherein the pseudo-random sequence initial factor c init satisfies the following formula:
C
init
=
[
2
31
-
d
⌊
n
ID
1024
⌋
+
(
2
10
(
N
symb
slot
n
s
,
f
μ
+
l
+
1
)
(
2
(
n
ID
mod
1024
)
+
1
)
+
(
n
ID
mod
1024
)
)
]
mod
2
31
.
16. A communications apparatus, comprising at least one processor and a memory coupled with the at least one processor, wherein the at least one processor is configured to:
receive a reference signal;
obtain a first sequence based on the reference signal;
obtain a second sequence based on a pseudo-random sequence initial factor c init ; and
perform correlation detection on the first sequence and the second sequence, wherein:
the pseudo-random sequence initial factor c init is represented by using 31 bits;
10 least significant bits in the 31 bits represent n ID mod 1024;
21 most significant bits in the 31 bits represent (N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1); and
d bits in the 21 most significant bits represent
⌊
n
I
D
1
0
2
4
⌋
,
and a value of d is related to a maximum value of n ID , wherein:
A T slot
N symb slot represents a quantity of orthogonal frequency-division multiplexing (OFDM) symbols in a slot,
└ ┘ represents rounding down,
n s, f μ represents an index of a slot in a frame,
l represents an index of an OFDM symbol in a slot,
n ID represents a reference signal sequence ID,
μ represents a parameter related to a subcarrier spacing, and
mod represents a modulo operation.
17. The apparatus according to claim 16 , wherein that c init is represented by using 31 bits comprises:
c init is obtained by first calculating a sum of N ID mod 1024 represented by using the 10 least significant bits,
(N symb slot n s, f μ +l+1)(2(n ID mod 1024)+1) represented by using the 21 most significant bits, and
⌊
n
I
D
1
0
2
4
⌋
represented by using the d bits, and then performing a modulo operation on the sum by using 2 31 .
18. The apparatus according to claim 16 , wherein the d bits overlap the 21 most significant bits, and the d bits are located in the middle of the 21 most significant bits.
19. The apparatus according to claim 16 , wherein when n ID is less than 4095, a value of d is 2.
20. The apparatus according to claim 16 , wherein the pseudo-random sequence initial factor c init satisfies the following formula:
C
init
=
[
2
31
-
d
⌊
n
ID
1024
⌋
+
(
2
10
(
N
symb
slot
n
s
,
f
μ
+
l
+
1
)
(
2
(
n
ID
mod
1024
)
+
1
)
+
(
n
ID
mod
1024
)
)
]
mod
2
31
.