Discontinued transmission of uplink sounding reference signals
A method and user equipment configured for discontinuous transmission, DTX, of sounding reference signals, SRSs, the user equipment served by a base station in a wireless network are disclosed. In some embodiments, a method includes, when operating in a first mode of operation, the method includes comparing a change in channel conditions to a channel condition threshold and transmitting an SRS only if the change in channel conditions exceeds the channel condition threshold. When operating in a second mode of operation, the method includes determining a content of an uplink data buffer and transmitting an SRS only if the uplink data buffer is not empty.
1. A method of discontinuous transmission, DTX, of sounding reference signals, SRSs, by a user equipment served by a base station in a wireless network, the method comprising:
when operating in a first mode of operation:
determining a change in channel conditions between a first channel estimation performed before a most recent SRS transmission and a second channel estimation performed after the most recent SRS transmission;
comparing the change in channel conditions to a channel condition threshold; and
transmitting an SRS only when the change in channel conditions exceeds the channel condition threshold; and
when operating in a second mode of operation:
determining a content of an uplink data buffer; and
transmitting an SRS when the uplink data buffer is not empty.
2. The method of claim 1 , wherein the transmitting of the SRS occurs when a time since a last SRS transmission exceeds a time threshold.
3. The method of claim 2 , wherein the time threshold and the channel condition threshold are signaled from the base station.
4. The method of claim 1 , wherein an indicator of the channel conditions is at least one of a channel quality indicator, a rank indictor and a precoding matrix indicator.
5. The method of claim 1 , wherein the SRS transmission occurs when one of:
there is data in the uplink data buffer; and
a time since a last SRS transmission exceeds a time threshold.
6. The method of claim 1 , wherein the SRS transmission occurs when an uplink logical channel priority exceeds a priority threshold.
7. A user equipment configured for discontinuous transmission, DTX, of sounding reference signals, SRSs, the user equipment served by
a base station in a wireless network, the user equipment comprising:
processing circuitry configured to:
when operating in a first mode of operation:
determine a change in channel conditions between a first channel estimation performed before a most recent SRS transmission and a second channel estimation performed after the most recent SRS transmission;
compare the change in channel conditions to a channel condition threshold; and
transmit an SRS when the change in channel conditions exceeds the channel condition threshold; and
when operating in a second mode of operation:
determine a content of an uplink data buffer; and
transmit an SRS when the uplink data buffer is not empty.
8. The user equipment of claim 7 , wherein the transmitting of the SRS occurs when a time since a last SRS transmission exceeds a time threshold.
9. The user equipment of claim 8 , wherein the time threshold and the channel condition threshold are signaled from the base station.
10. The user equipment of claim 7 , wherein an indicator of the channel conditions is at least one of a channel quality indicator, a rank indictor and a precoding matrix indicator.
11. The user equipment of claim 7 , wherein the SRS transmission occurs when one of:
there is data in the uplink data buffer; and
a time since a last SRS transmission exceeds a time threshold.
12. The user equipment of claim 7 , wherein the SRS transmission occurs when an uplink logical channel priority exceeds a priority threshold.
13. A user equipment configured for discontinuous transmission, DTX, of sounding reference signals, SRSs, the user equipment served by a base station in a wireless network, the user equipment comprising:
processing circuitry configured to:
determine a change in channel conditions between a first channel estimation performed before a most recent SRS transmission and a second channel estimation performed after the most recent SRS transmission; and
compare the change in channel conditions to a channel condition threshold; and
a transceiver module configured to transmit an SRS when the change in channel conditions exceeds the channel condition threshold.
14. The user equipment of claim 13 , wherein the transmitting of the SRS occurs when a time since a last SRS transmission exceeds a time threshold.
15. The user equipment of claim 14 , wherein the time threshold and the channel condition threshold are signaled from the base station.
16. The user equipment of claim 13 , wherein the SRS transmission occurs when one of:
there is data in an uplink data buffer; and
a time since a last SRS transmission exceeds a time threshold.
17. The user equipment of claim 13 , wherein the SRS transmission occurs when an uplink logical channel priority exceeds a priority threshold.