Method and apparatus for providing enhanced reference signal received power estimation
View Patent ↗A method and an apparatus for providing reference signal received power (RSRP) are disclosed herein. According to one embodiment, a signal is received in a modem. Signal elements at reference signal (RS) locations are extracted from the received signal. The signal elements are descrambled to remove a RS sequence. A linear average of the descrambled signal elements is performed to form virtual reference signal (VRS) elements. The RSRP is estimated from the VRS elements.
1. A method of estimating reference signal received power (RSRP), the method comprising:
receiving a signal in a modem;
extracting signal elements at reference signal (RS) locations from the received signal;
descrambling the signal elements at the RS locations to remove a RS sequence;
performing a linear average of the descrambled signal elements to form virtual reference signal (VRS) elements, wherein the VRS elements have smaller noise variances than original RS elements in corresponding locations of the received signal; and
estimating the RSRP using the VRS elements in place of the original RS elements.
2. The method of claim 1 , wherein, in performing the linear average, constraints are imposed on a weighting vector to reduce noise variance and maintain power of the descrambled signal elements.
3. The method of claim 2 , wherein, in performing the linear average, the weighting vector is dynamically adjusted based on a channel type or a system parameter.
4. The method of claim 1 , wherein, in performing the linear average, each VRS element is determined by:
v
m
,
k
=
w
k
T
[
y
8
m
-
3
,
2
y
8
m
-
3
,
4
y
8
m
-
7
,
2
y
8
m
-
7
,
4
]
,
k
∈
{
1
,
2
,
…
,
11
}
,
m
{
1
,
2
,
…
,
30
}
where v m,k is a given VRS element, w k T is a weighting vector, and each y is one of four closest descrambled signal elements to the given VRS element.
5. The method of claim 1 , wherein, in performing the linear average, two descrambled signal elements are used for a given VRS element.
6. The method of claim 1 , wherein, in performing the linear average, four descrambled signal elements are used for a given VRS element.
7. The method of claim 1 , wherein estimating the RSRP comprises calculating at least one of a horizontal correlation and a vertical correlation from the VRS elements.
8. The method of claim 7 , wherein the vertical correlation is determined by:
g
0
=
1
149
(
∑
m
=
1
30
(
v
m
,
1
v
m
,
3
*
+
v
m
,
3
v
m
,
6
*
+
v
m
,
6
v
m
,
9
*
+
v
m
,
9
v
m
,
11
*
)
+
∑
n
=
1
29
v
n
,
11
v
n
+
1
,
1
*
)
where g 0 is the vertical correlation, and v is a given VRS element; and
the horizontal correlation is determined by:
g
1
=
1
90
(
∑
m
=
1
30
v
m
,
2
v
m
,
4
*
+
v
m
,
5
v
m
,
7
*
+
v
m
,
8
v
m
,
10
*
)
where g 1 is the horizontal correlation, and v is a given VRS element.
9. The method of claim 8 , wherein the horizontal correlation and the vertical correlation are calculated, and estimating the RSRP comprises estimating one of a coherent RSRP and non-coherent RSRP from the horizontal correlation and the vertical correlation.
10. The method of claim 9 , wherein:
the coherent RSRP is determined by:
RSRP non coh =½| g 0 +g 1 |
the non-coherent RSRP is determined by:
RSRP non-coh =½| g 0 |+½| g 1 |.
11. An electronic device, comprising:
a processor; and
a non-transitory computer readable storage medium storing instructions that, when executed, cause the processor to:
receive a signal;
extract signal elements at reference signal (RS) locations from the received signal;
descramble the signal elements to remove an RS sequence;
perform a linear average of the descrambled signal elements to form virtual reference signal (VRS) elements, wherein the VRS elements have smaller noise variances than original RS elements in corresponding locations of the received signal; and
estimate the RSRP from the VRS elements in place of the original RS elements.
12. The electronic device of claim 11 , wherein, in performing the linear average, constraints are imposed on a weighting vector to reduce noise variance and maintain power of the descrambled signal elements.
13. The electronic device of claim 12 , wherein, in performing the linear average, the weighting vector is dynamically adjusted based on a channel type or a system parameter.
14. The electronic device of claim 11 , wherein, in performing the linear average, each VRS element is determined by:
v
m
,
k
=
w
k
T
[
y
8
m
-
3
,
2
y
8
m
-
3
,
4
y
8
m
-
7
,
2
y
8
m
-
7
,
4
]
,
k
∈
{
1
,
2
,
…
,
11
}
,
m
{
1
,
2
,
…
,
30
}
.
where v m,k is a given VRS element, w k T is a weighting vector, and each y is one of four closest descrambled signal elements to the given VRS element.
15. The electronic device of claim 11 , wherein, in performing the linear average, two descrambled signal elements are used for a given VRS element.
16. The electronic device of claim 11 , wherein, in performing the linear average, four descrambled signal elements are used for a given VRS element.
17. The electronic device of claim 11 , wherein estimating the RSRP comprises calculating at least one of a horizontal correlation and a vertical correlation from the VRS elements.
18. The electronic device of claim 17 , wherein
The vertical correlation is determined by:
g
0
=
1
149
(
∑
m
=
1
30
(
v
m
,
1
v
m
,
3
*
+
v
m
,
3
v
m
,
6
*
+
v
m
,
6
v
m
,
9
*
+
v
m
,
9
v
m
,
11
*
)
+
∑
n
=
1
29
v
n
,
11
v
n
+
1
,
1
*
)
where g 0 is the vertical correlation, and v is a given VRS element; and
the horizontal correlation is determined by:
g
1
=
1
90
(
∑
m
=
1
30
v
m
,
2
v
m
,
4
*
+
v
m
,
5
v
m
,
7
*
+
v
m
,
8
v
m
,
10
*
)
where g 1 is the horizontal correlation, and v is a given VRS element.
19. The electronic device of claim 18 , wherein the horizontal correlation and the vertical correlation are calculated, and estimating the RSRP comprises estimating one of a coherent RSRP and non-coherent RSRP from the horizontal correlation and the vertical correlation.
20. The electronic device of claim 19 , wherein:
the coherent RSRP is determined by:
RSRP coh =½| g 0 +g 1 |
the non-coherent RSRP is determined by:
RSRP non-coh =½| g 0 |+½| g 1 |.