Apparatus and method for transmission of uplink sounding reference signals in a wireless network
A mobile station for use in a wireless network that operates according to the Long-Term Evolution Advanced (LTE-A) standard is configured to transmit an aperiodic sounding reference signal (SRS) to a base station in response to a triggering grant received from the base station. The bandwidth on which the mobile station transmits the aperiodic SRS depends on a type of the triggering grant. The type of the triggering grant is one of a downlink grant, an uplink multiple-input, multiple-output (MIMO) grant, and an uplink single-input, multiple-output (SIMO) grant.
1. A method of a terminal for a communication system, the method comprising:
identifying a sounding reference signal (SRS) transmit power by power scaling based on a scaling factor if a total transmit power of a symbol for an SRS exceeds a user equipment (UE) maximum transmit power;
when the SRS is transmitted on at least two component carriers, scaling transmit power of the SRS on each of the at least two component carriers based on following equation:
∑
c
w
c
P
SRS
,
c
(
i
)
≤
P
CMAX
where P CMAX is the UE maximum transmit power, w c is a scaling factor, and P SRS,c is the transmit power of the SRS on a component carrier c of the at least two component carriers;
identifying an SRS bandwidth based on a grant which triggers the SRS; and
transmitting the SRS based on the identified SRS transmit power and SRS bandwidth.
2. The method of claim 1 , wherein the scaling factor is the same on the component carriers.
3. The method of claim 1 , wherein if the grant is an uplink grant, the SRS bandwidth is determined as a first bandwidth and if the grant is a downlink grant, the SRS bandwidth is determined as a second bandwidth.
4. The method of claim 1 , wherein the SRS in a subframe on a component carrier is triggered based on at least one grant which is associated with same SRS parameters.
5. A method of a base station for a communication system, the method comprising:
transmitting a grant which triggers a sounding reference signal (SRS);
receiving the SRS based on an SRS transmit power and an SRS bandwidth,
wherein the SRS transmit power is identified by power scaling based on a scaling factor if a total transmit power of a symbol for the SRS exceeds a user equipment (UE) maximum transmit power,
wherein the SRS bandwidth is identified based on the grant, and
wherein, when the SRS is received on the at least two component carriers, the transmit power of the SRS on each of the at least two component carriers is scaled based on following equation:
∑
c
w
c
P
SRS
,
c
(
i
)
≤
P
CMAX
where P CMAX is the UE maximum transmit power, w c is the scaling factor, and P SRS,c is a transmit power of the SRS on a component carrier c of the at least two component carriers.
6. The method of claim 5 , wherein the scaling factor is the same on the component carriers.
7. The method of claim 5 , if the grant is an uplink grant, the SRS bandwidth is determined as a first bandwidth and if the grant is a downlink grant, the SRS bandwidth is determined as a second bandwidth.
8. The method of claim 5 , wherein the SRS in a subframe on a component carrier is triggered based on at least one grant which is associated with same SRS parameters.
9. A terminal for a communication system, the terminal comprising:
a transmitter; and
processing circuitry configured to
identify a sounding reference signal (SRS) transmit power by power scaling based on a scaling factor if a total transmit power of a symbol for an SRS exceeds a user equipment (UE) maximum transmit power,
when the SRS is transmitted on at least two component carriers, scale each transmit power of the SRS on the at least two component carriers based on following equation:
∑
c
w
c
P
SRS
,
c
(
i
)
≤
P
CMAX
where P CMAX is the UE maximum transmit power, w c is a scaling factor, and P SRS,c is a transmit power of the SRS on a component carrier c of the at least two component carriers,
identify an SRS bandwidth based on a grant which triggers the SRS, and
control the transmitter to transmit the SRS based on the identified SRS transmit power and SRS bandwidth.
10. The terminal of claim 9 , wherein the scaling factor is the same on the component carriers.
11. The terminal of claim 9 , wherein if the grant is an uplink grant, the SRS bandwidth is determined as a first bandwidth and if the grant is a downlink grant, the SRS bandwidth is determined as a second bandwidth.
12. The terminal of claim 9 , wherein the SRS in a subframe on a component carrier is triggered based on at least one grant which is associated with same SRS parameters.
13. A base station of a communication system, the base station comprising:
a transmitter;
a receiver; and
a controller configured to control the transmitter to transmit a grant which triggers a sounding reference signal (SRS) and to control the receiver to receive the SRS based on an SRS transmit power and an SRS bandwidth, and
wherein the SRS transmit power is identified by power scaling based on a scaling factor if a total transmit power of a symbol for the SRS exceeds a user equipment (UE) maximum transmit power,
wherein the SRS bandwidth is identified based on the grant, and
wherein, when the SRS is received on the at least two component carriers, transmit power of the SRS on each of the at least two component carriers is scaled based on following equation:
∑
c
w
c
P
SRS
,
c
(
i
)
≤
P
CMAX
where P CMAX is the UE maximum transmit power, w c is the scaling factor, and P SRS,c is a transmit power of the SRS on a component carrier c of the at least two component carriers.
14. The base station of claim 13 , wherein the scaling factor is the same on the component carriers.
15. The base station of claim 13 , if the grant is an uplink grant, the SRS bandwidth is determined as a first bandwidth and if the grant is a downlink grant, the SRS bandwidth is determined as a second bandwidth.
16. The base station of claim 13 , wherein the SRS in a subframe on a component carrier is triggered based on at least one grant which is associated with same SRS parameters.