Power control for the sidelink control channel
According to some embodiments, a method is performed by a wireless device. The method comprises obtaining a data channel transmit power for transmitting on a sidelink data channel to a receiving wireless device, obtaining a control channel transmit power for transmitting on a sidelink control channel, and transmitting on the sidelink data channel at the data channel transmit power and on the sidelink control channel at the control channel transmit power. In certain embodiments, the control channel transmit power is based on the data channel transmit power. In other embodiments, the control channel transmit power is determined independently of the data channel transmit power.
1. A method performed by a wireless device, the method comprising:
obtaining a data channel transmit power for transmitting on a sidelink data channel to a receiving wireless device;
obtaining a control channel transmit power for transmitting on a sidelink control channel, wherein the control channel transmit power is determined based on adding a boost value to the data channel transmit power, wherein the boost value depends on a calculation, the calculation based at least in part on an estimated path loss between the wireless device and the receiving wireless device, and
transmitting on the sidelink data channel at the data channel transmit power and on the sidelink control channel at the control channel transmit power.
2. The method of claim 1 , wherein:
the control channel transmit power comprises:
determining the control channel transmit power at the wireless device or, receiving, from a network node, signaling that indicates the control channel transmit power, and
the data channel transmit power comprises:
determining the data channel transmit power at the wireless device, or
receiving, from a network node, signaling that indicates the data channel transmit power.
3. The method of claim 1 , wherein:
possible values for the data channel transmit power are divided into power intervals; and the control channel transmit power is determined based on which power interval the data channel transmit power falls into.
4. The method of claim 3 , wherein:
each of the power intervals corresponds to a respective boost value; and the control channel transmit power is determined based on adding a boost value to the data channel transmit power, the boost value corresponding to the power interval into which the data channel transmit power falls.
5. The method of claim 3 , wherein:
each of the power intervals corresponds to a respective range of boost values; and the control channel transmit power is determined based on adding a boost value to the data channel transmit power, the boost value selected from the range of boost values corresponding to the power interval into which the data channel transmit power falls.
6. The method of claim 1 , wherein the boost value is based on one or more of a modulation order, a coding rate, or a target transmission range of the sidelink control channel.
7. The method of claim 1 wherein the control channel transmit power is equal to the data channel transmit power when the data channel transmit power exceeds a predetermined threshold value.
8. The method of claim 1 , wherein the data channel transmit power varies based on whether the sidelink data channel is multiplexed with the sidelink control channel.
9. The method of claim 1 , further comprising reducing the data channel transmit power when a sum of the data channel transmit power and the control channel transmit power exceeds a maximum transmit power, the data channel transmit power reduced such that it is equal to or less than the difference between the maximum transmit power and the control channel transmit power.
10. The method of claim 1 , wherein the transmitting comprises:
using a first group of one or more symbols to transmit on both the sidelink data channel and the sidelink control channel, the transmitting on the sidelink data channel transmitted at the data channel transmit power and the transmitting on the sidelink control channel at the control channel transmit power; and
using a second group of one or more symbols to transmit on only the sidelink data channel, the transmitting on the sidelink data channel at a second data channel transmit power determined by adding the data channel transmit power and the control channel transmit power,
wherein the first group of one or more symbols and the second group of one or more symbols are adjacent symbols within a same slot or subframe.
11. The method of claim 1 , wherein the control channel transmit power is determined based on at least a target transmission range for the wireless device and a modulation and coding scheme (MCS) for transmitting to the receiving wireless device.
12. The method of claim 1 , wherein:
the maximum transmit power varies over the duration of the transmission by the wireless device; and
the method further comprises adjusting the control channel transmit power as the maximum transmit power changes.
13. The method of claim 1 , further comprising adjusting the MCS of the sidelink control channel based on the control channel transmit power.
14. A wireless device, the wireless device comprising processing circuitry operable to:
perform the steps of claim 1 .
15. A method performed by a network node, the method comprising:
determining a control channel transmit power for a wireless device to use when transmitting on a sidelink control channel, wherein the control channel transmit power is based on a data channel transmit power that the wireless device is to use when transmitting on a sidelink data channel, wherein the control channel transmit power is determined based on adding a boost value to the data channel transmit power, wherein the boost value depends on a calculation, the calculation based at least in part on an estimated path loss between the wireless device and a receiving wireless device; and
indicating the control channel transmit power to the wireless device.