Uplink power control on unlicensed carriers
Systems and methods relating to transmit power control are disclosed. In some embodiments, a method of operation of a radio access node for providing transmit power control commands to a wireless device for uplink (UL) transmission on a cell that operates in an unlicensed frequency spectrum is provided. The method comprises indicating, for the cell that operates in the unlicensed frequency spectrum, a dynamic Transmit Power Control (TPC) command using a downlink (DL) control channel which indicates a DL-UL allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum. In some embodiments, the DL control channel is a common DL control channel. In some other embodiments, the DL channel is a common Physical Downlink Control Channel (PDCCH).
1. A method of operation of a radio access node for providing transmit power control commands to a wireless device for uplink transmission on a cell that operates in an unlicensed frequency spectrum, comprising:
indicating, for the cell that operates in the unlicensed frequency spectrum, a dynamic transmit power control command using a downlink control channel which indicates a downlink-uplink allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum, wherein indicating the dynamic transmit power control command comprises transmitting the downlink control channel comprising an indication of the downlink-uplink allocation of upcoming subframes in the cell and an indication of the dynamic transmit power control command, wherein the indication of the dynamic transmit power control command comprises at least one bit.
2. The method of claim 1 wherein the dynamic transmit power control command is applicable to physical uplink shared channel, short physical uplink control channel, enhanced physical uplink control channel, and/or sounding reference signal transmissions.
3. The method of claim 1 wherein the radio access node is a MuLTEfire, MF, access point.
4. A method of operation of a wireless device for uplink transmission on a cell that operates in an unlicensed frequency spectrum, comprising:
receiving, from a radio access node serving the cell that operates in the unlicensed frequency spectrum, an indication of a dynamic transmit power control command for the cell that operates in the unlicensed frequency spectrum, the indication of the dynamic transmit power control command being comprised in a downlink control channel that also comprises an indication of a downlink-uplink allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum, wherein the indication comprises transmit power control commands for multiple subframes of the upcoming subframes.
5. The method of claim 4 further comprising utilizing the indication of the dynamic transmit power control command for uplink transmission on the cell that operates in the unlicensed frequency spectrum.
6. The method of claim 5 wherein utilizing the indication of the dynamic transmit power control command comprises:
performing a Listen-Before-Talk, LBT, procedure for the cell that operates in the unlicensed frequency spectrum; and
transmitting an uplink transmission on the cell that operates in the unlicensed frequency spectrum if a result of the LBT procedure is a decision that a corresponding channel is clear.
7. The method of claim 4 wherein the multiple subframes include at least one non-consecutive subframe.
8. The method of claim 4 wherein the downlink control channel is a common physical downlink control channel.
9. The method of claim 4 wherein the dynamic transmit power control command is applicable to physical uplink shared channel, short physical uplink control channel, enhanced physical uplink control channel, and/or sounding reference signal transmissions.
10. The method of claim 4 wherein the radio access node a MuLTEfire, MF, access point.
11. A wireless device operative to perform uplink transmission on a cell that operates in an unlicensed frequency spectrum, comprising:
a processor; and
memory comprising instructions executable by the processor whereby the wireless device is operable to:
receive, from a radio access node serving the cell that operates in the unlicensed frequency spectrum, an indication of a dynamic transmit power control command for the cell that operates in the unlicensed frequency spectrum, the indication of the dynamic transmit power control command being comprised in a downlink control channel that also comprises an indication of a downlink-uplink allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum, wherein the indication comprises transmit power control commands for multiple subframes of the upcoming subframes.
12. A method of operation of a wireless device for uplink transmission on a cell that operates in an unlicensed frequency spectrum, comprising:
setting one or more uplink power control parameters for autonomous uplink transmission of multiple subframes on the cell that operates in the unlicensed frequency spectrum based on:
uplink power control information comprised in a most recent downlink control channel received by the wireless device,
uplink power control information comprised in a most recent uplink grant received by the wireless device, or
signaling received on another serving cell of the wireless device.
13. The method of claim 12 further comprising transmitting an autonomous uplink transmission on the cell that operates in the unlicensed frequency spectrum in accordance with the one or more uplink power control parameters.
14. The method of claim 12 wherein setting the one or more uplink power control parameters comprises setting the one or more uplink power control parameters for autonomous uplink transmission on the cell that operates in the unlicensed frequency spectrum based on uplink power control information comprised in a most recent downlink control channel received by the wireless device.
15. The method of claim 14 wherein the most recent downlink control channel is a common downlink control channel or a common physical downlink control channel.
16. The method of claim 12 wherein setting the one or more uplink power control parameters comprises setting the one or more uplink power control parameters for autonomous uplink transmission on the cell that operates in the unlicensed frequency spectrum based on uplink power control information comprised in a most recent uplink grant received by the wireless device.
17. The method of claim 12 wherein setting the one or more uplink power control parameters comprises setting the one or more uplink power control parameters for autonomous uplink transmission on the cell that operates in the unlicensed frequency spectrum based on signaling received on another serving cell of the wireless device.
18. The method of claim 12 wherein the cell that operates in the unlicensed frequency spectrum is a secondary cell of the wireless device that serves the wireless device together with a primary cell of the wireless device that operates in a licensed frequency spectrum in accordance with a carrier aggregation scheme.
19. The method of claim 12 wherein the cell that operates in the unlicensed frequency spectrum is a standalone serving cell of the wireless device.