Method for transmitting uplink sounding reference signal for LTE system
Disclosed are a method and apparatus for transmitting an uplink Sounding Reference Signal (SRS), the method including identifying a number of downlink and uplink switch points within a radio frame N sp and a system frame number n f , calculating a value of n SRS according to a number of downlink and uplink switch points within a radio frame N sp , and the system frame number n f for transmitting the SRS, determining a frequency-domain starting position of the SRS with n SRS , and transmitting the SRS at the determined frequency-domain starting position.
1. A method for transmitting an uplink Sounding Reference Signal (SRS), the method comprising steps of:
a) identifying a number of downlink and uplink switch points within a radio frame, N sp , and a system frame number n f ;
b) calculating a value of n SRS according to the number of downlink and uplink switch points within a radio frame N sp , and the system frame number n f for transmitting the SRS;
c) determining a frequency-domain starting position of the SRS based on n SRS ; and
d) transmitting the SRS at the determined frequency-domain starting position.
2. The method of claim 1 , wherein n SRS is calculated by n SRS =n f ×L+k, for 2 ms SRS periodicity in a TDD system,
where n f is the system frame number, L is 2*N sp being the number of downlink and uplink switch points within a radio frame, and k can be 0, 1, 2 or 3.
3. The method of claim 1 , further comprising, after step a) and before step b):
calculating a frequency-domain increment to be updated for the SRS according to the obtained n SRS ; and
calculating a frequency position index for transmitting the SRS according to the obtained frequency-domain increment.
4. The method of claim 3 , wherein the frequency-domain increment is calculated by:
F
b
(
n
SRS
)
=
{
(
N
b
/
2
)
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
+
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
2
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
even
⌊
N
b
/
2
⌋
⌊
n
SRS
/
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
odd
,
where N b is obtained according to a Radio Resource Control (RRC) signaling and b hop denotes SRS frequency-hopping parameter, 0≦b hop ≦3, which is provided by a higher-layer parameter.
5. The method of claim 4 , wherein the frequency position index is calculated by:
n
b
=
{
⌊
4
n
RRC
/
m
SRS
,
b
⌋
b
≤
b
hop
{
F
b
(
n
SRS
)
+
⌊
4
n
RRC
/
m
SRS
,
b
⌋
}
mod
N
b
else
,
where m SRS,b is obtained by reading the RRC signaling and n RRC is given by a higher-layer parameter.
6. The method of claim 5 , wherein the frequency-domain starting position k 0 is calculated by:
k
0
=
k
0
′
+
∑
b
=
0
B
SRS
2
M
sc
,
b
RS
n
b
k
0
′
=
(
⌊
N
RB
UL
/
2
⌋
-
m
SRS
,
0
/
2
)
N
SC
RB
+
k
TC
M
sc
,
b
RS
=
m
SRS
,
b
N
sc
RB
/
2
,
where m SRS,0 obtained from a cell-specific SRS parameter, N sc RB denotes resource block size in the frequency domain, expressed as a number of subcarriers, k TC ε{0,1} denotes a Comb parameter, and N RB UL denotes uplink bandwidth configuration, expressed in multiples of N sc RB .
7. The method of claim 2 , wherein the identifying step further comprises:
indexing a first SC-FDMA symbol for transmitting the SRS in a radio frame as k=0;
indexing a second SC-FDMA symbol for transmitting the SRS in a radio frame as k=1;
indexing a third SC-FDMA symbol for transmitting the SRS in a radio frame as k=2; and
indexing a fourth SC-FDMA symbol for transmitting the SRS in a radio frame as k=3.
8. A User Equipment (UE) for transmitting an uplink Sounding Reference Signal (SRS) comprising:
an SRS sequence generator for generating an SRS sequence;
a physical resource mapper for transmitting the SRS; and
a transmitter for transmitting the SRS at a determined frequency-domain starting position,
wherein the physical resource mapper is adapted to perform the following sequence of steps:
a) identifying a number of downlink and uplink switch points within a radio frame, N sp , and a system frame number n f ;
b) calculating a value of n SRS according to the number of downlink and uplink switch points within a radio frame N sp , and the system frame number n f for transmitting the SRS; and
c) determining a frequency-domain starting position of the SRS based on n SRS .
9. The UE of claim 8 , wherein n SRS is calculated by n SRS =n f ×L+k, for 2 ms SRS periodicity in a TDD system,
where n f is the system frame number, L is 2*N sp being the number of downlink and uplink switch points within a radio frame, and k can be 0, 1, 2 or 3.
10. The UE of claim 8 , wherein the physical resource mapper performs further steps of:
calculating a frequency-domain increment to be updated for the SRS according to the obtained n SRS ; and
calculating a frequency position index for transmitting the SRS according to the obtained frequency-domain increment.
11. The UE of claim 10 , wherein the frequency-domain increment is calculated by:
F
b
(
n
SRS
)
=
{
(
N
b
/
2
)
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
+
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
2
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
even
⌊
N
b
/
2
⌋
⌊
n
SRS
/
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
odd
,
where N b is obtained according to an RRC(Radio Resource Control) signaling and b hop denotes SRS frequency-hopping parameter, 0≦b hop ≦3, which is provided by a higher-layer parameter.
12. The UE of claim 11 , wherein the frequency position index is calculated by:
n
b
=
{
⌊
4
n
RRC
/
m
SRS
,
b
⌋
b
≤
b
hop
{
F
b
(
n
SRS
)
+
⌊
4
n
RRC
/
m
SRS
,
b
⌋
}
mod
N
b
else
,
where M SRS,b is obtained by reading the RRC signaling and n RRC is given by a higher-layer parameter.
13. The UE of claim 12 , wherein, the frequency-domain starting position k 0 is calculated by:
k
0
=
k
0
′
+
∑
b
=
0
B
SRS
2
M
sc
,
b
RS
n
b
k
0
′
=
(
⌊
N
RB
UL
/
2
⌋
-
m
SRS
,
0
/
2
)
N
SC
RB
+
k
TC
M
sc
,
b
RS
=
m
SRS
,
b
N
sc
RB
/
2
,
where m SRS,0 obtained from a cell-specific SRS parameter, N sc RB denotes resource block size in the frequency domain, expressed as a number of subcarriers, k TC ε{0,1} denotes a Comb parameter, and N RB UL denotes uplink bandwidth configuration, expressed in multiples of N sc RB .
14. The UE of claim 9 , wherein the physical resource mapper further performs:
indexing a first SC-FDMA symbol for transmitting the SRS in a radio frame as k=0,
indexing a second SC-FDMA symbol for transmitting the SRS in a radio frame as k=1,
indexing a third SC-FDMA symbol for transmitting the SRS in a radio frame as k=2, and
indexing a fourth SC-FDMA symbol for transmitting the SRS in a radio frame as k=3.
15. A method for receiving an uplink Sounding Reference Signal (SRS), the method comprising steps of:
a) identifying a number of downlink and uplink switch points within a radio frame, N sp , and a system frame number n f ;
b) calculating a value of n SRS according to the number of downlink and uplink switch points within a radio frame N sp , and the system frame number n f for transmitting the SRS;
c) determining a frequency-domain starting position of the SRS based on n SRS ; and
d) receiving the SRS at the determined frequency-domain starting position.
16. The method of claim 15 , wherein n SRS is calculated by n SRS =n f ×L+k, for 2 ms SRS periodicity in a TDD system,
where n f is the system frame number, L is 2*N sp being the number of downlink and uplink switch points within a radio frame, and k can be 0, 1, 2 or 3.
17. The method of claim 15 , further comprising:
calculating a frequency-domain increment to be updated for the SRS according to the obtained n SRS ; and
calculating a frequency position index for transmitting the SRS according to the obtained frequency-domain increment.
18. The method of claim 17 , wherein the frequency-domain increment is calculated by:
F
b
(
n
SRS
)
=
{
(
N
b
/
2
)
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
+
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
2
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
even
⌊
N
b
/
2
⌋
⌊
n
SRS
/
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
odd
,
where N b is obtained according to a Radio Resource Control (RRC) signaling and b hop denotes SRS frequency-hopping parameter, 0≦b hop ≦3, which is provided by a higher-layer parameter.
19. The method of claim 18 , wherein the frequency position index is calculated by:
n
b
=
{
⌊
4
n
RRC
/
m
SRS
,
b
⌋
b
≤
b
hop
{
F
b
(
n
SRS
)
+
⌊
4
n
RRC
/
m
SRS
,
b
⌋
}
mod
N
b
else
,
where m SRS,b is obtained by reading the RRC signaling and n RRC is given by a higher-layer parameter.
20. The method of claim 19 , wherein the frequency-domain starting position k 0 is calculated by:
k
0
=
k
0
′
+
∑
b
=
0
B
SRS
2
M
sc
,
b
RS
n
b
k
0
′
=
(
⌊
N
RB
UL
/
2
⌋
-
m
SRS
,
0
/
2
)
N
SC
RB
+
k
TC
M
sc
,
b
RS
=
m
SRS
,
b
N
sc
RB
/
2
,
where M SRS,0 obtained from a cell-specific SRS parameter, N sc RB denotes resource block size in the frequency domain, expressed as a number of subcarriers, k TC ε{0,1} denotes a Comb parameter, and N RB UL denotes uplink bandwidth configuration, expressed in multiples of N sc RB .
21. The method of claim 16 , wherein the identifying step comprising:
indexing a first SC-FDMA symbol for transmitting the SRS in a radio frame as k=0;
indexing a second SC-FDMA symbol for transmitting the SRS in a radio frame as k=1;
indexing a third SC-FDMA symbol for transmitting the SRS in a radio frame as k=2; and
indexing a fourth SC-FDMA symbol for transmitting the SRS in a radio frame as k=3.
22. A base station for receiving an uplink Sounding Reference Signal (SRS), the base station comprising:
an SRS sequence generator for generating an SRS sequence;
a physical resource mapper for transmitting the SRS; and
a receiver for receiving the SRS at a determined frequency-domain starting position,
wherein the physical resource mapper is adapted to sequentially perform steps of:
a) identifying a number of downlink and uplink switch points within a radio frame, N sp , and a system frame number n f ;
b) calculating a value of n SRS according to the number of downlink and uplink switch points within a radio frame N sp , and the system frame number n f for transmitting the SRS; and
c) determining a frequency-domain starting position of the SRS based on n SRS .
23. The base station of claim 22 , wherein n SRS is calculated by n SRS =n f ×L+k, for 2 ms SRS periodicity in a TDD system,
where n f is the system frame number, L is 2*N sp being the number of downlink and uplink switch points within a radio frame, k can be 0, 1, 2 or 3.
24. The base station of claim 22 , the physical resource mapper further comprising:
calculating a frequency-domain increment to be updated for the SRS according to the obtained n SRS ; and
calculating a frequency position index for transmitting the SRS according to the obtained frequency-domain increment.
25. The base station of claim 24 , wherein the frequency-domain increment is calculated by:
F
b
(
n
SRS
)
=
{
(
N
b
/
2
)
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
+
⌊
n
SRS
mod
∏
b
′
=
b
hop
b
N
b
′
2
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
even
⌊
N
b
/
2
⌋
⌊
n
SRS
/
∏
b
′
=
b
hop
b
-
1
N
b
′
⌋
if
N
b
odd
,
where N b is obtained according to a Radio Resource Control (RRC) signaling and b hop denotes SRS frequency-hopping parameter, 0≦b hop ≦3, which is provided by a higher-layer parameter.
26. The base station of claim 25 , wherein the frequency position index is calculated by:
n
b
=
{
⌊
4
n
RRC
/
m
SRS
,
b
⌋
b
≤
b
hop
{
F
b
(
n
SRS
)
+
⌊
4
n
RRC
/
m
SRS
,
b
⌋
}
mod
N
b
else
,
where m SRS,b is obtained by reading the RRC signaling and n RRC is given by a higher-layer parameter.
27. The base station of claim 26 , wherein the frequency-domain starting position k 0 is calculated by:
k
0
=
k
0
′
+
∑
b
=
0
B
SRS
2
M
sc
,
b
RS
n
b
k
0
′
=
(
⌊
N
RB
UL
/
2
⌋
-
m
SRS
,
0
/
2
)
N
SC
RB
+
k
TC
M
sc
,
b
RS
=
m
SRS
,
b
N
sc
RB
/
2
,
where m SRS,0 obtained from a cell-specific SRS parameter, N sc RB denotes resource block size in the frequency domain, expressed as a number of subcarriers, k TC ε{0,1} denotes a Comb parameter, and N RB UL denotes uplink bandwidth configuration, expressed in multiples of N sc RB .
28. The base station of claim 23 , wherein the physical resource mapper further performs:
indexing a first SC-FDMA symbol for transmitting the SRS in a radio frame as k=0,
indexing a second SC-FDMA symbol for transmitting the SRS in a radio frame as k=1;
indexing a third SC-FDMA symbol for transmitting the SRS in a radio frame as k=2; and
indexing a fourth SC-FDMA symbol for transmitting the SRS in a radio frame as k=3.