FIELD
5 [0001] Non-limiting and example embodiments of the present disclosure generally relate
to a technical field of wireless communication, and specifically to methods, apparatuses and
computer program products for power control in a wireless communication system.
BACKGROUND
10 [0002] This section introduces aspects that may facilitate better understanding of the
disclosure. Accordingly, the statements of this section are to be read in this light and are not
to be understood as admissions about what is in the prior art or what is not in the prior art.
[0003] In wireless communication systems, there is a requirement for supporting
increasing types of services. For instance, Vehicle to anything (V2X) sidelink (SL) was
15 introduced in Long Term Evolution (LTE) Release 14 developed by the Third Generation
Partnership Project (3GPP) to support direct communication of basic road safety services
between vehicle and vehicle/pedestrian/infrastructure.
[0004] In the wireless communication systems with increasing number of devices and
services, transmission power of a device has to be well controlled, so as to guarantee
20 satisfying communication performance of the device, minimized power consumption, and/or
minimized interference to other devices.
SUMMARY
[0005] Various embodiments of the present disclosure mainly aim at providing methods,
25 apparatuses and computer program products for power control in a wireless communication
system.
[0006] In a first aspect of the disclosure, there is provided a method implemented at a
first terminal device. The method comprises determining one or more power control
parameters for a transmission from a second terminal device to the first terminal device;
30 transmitting the one or more power control parameters to the second terminal device; and
receiving the transmission from the second tenninal device, the transmission being controlled
based on the one or more power control parameters.
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[0007] In some embodiments, the one or more power control parameters may include at
least one of: a power adjustment value relative to a reference power level, a base power level,
and a pathloss compensation factor. The reference power level may comprises a
transmission power determined for the transmission based on one or more of: a power control
5 parameter which is configured by a base station or pre-configured, a pathloss between the
second terminal device and the base station, and a power compensation associated with a
modulation and coding scheme, (MCS) and/or a quality of service (QoS) level of the
transmission.
[0008] In some embodiments, determining one or more power control parameters may
1 0 compnse: determining the power adjustment value by comparing a measured performance
metric to a target performance metric. In some embodiments, the performance metric may
comprise a signal to interference and noise power ratio (SINR).
[0009] In some embodiments, the method may further compnse determining an
averaged receiving SINR based on one or more transmissions from the second device to
15 obtain the measured performance metric, wherein transmission power of the one or more
transmissions is determined based on at least one of: a power control parameter configured by
a base station or preconfigured, a pathloss between the second terminal device and the base
station, and a power compensation associated with a MCS and/or a QoS level of the
transmission. In some embodiments, determining the averaged receiving SINR based on the
20 one or more transmissions from the second device may comprise: obtaining an estimated
receiving SINR for each of the one or more transmissions; and determining an averaged value
of the estimated receiving SINRs as the averaged receiving SINR.
[0010] In some embodiments, obtaining the estimated receiving SINR for each of the
one or more transmissions may comprise: obtaining the estimated receiving SINR by
25 removing power compensation associated with a MCS and/or a QoS level for each of the one
or more transmissions.
[0011] In some embodiments, determining the one or more power control parameters
may comprise: detennining the base power level and the pathless compensation factor based
on a target receiving SINR and a pathloss between the first terminal device and the second
30 terminal device. In some embodiments, the determined the base power level and the
pathloss compensation factor satisfies a restriction that a receiving power at the first terminal
device is no larger than a target receiving power.
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[0012] In some embodiments, the method may further comprise: determining a power
offset for a further transmission from the second terminal device based on one or more
transmissions received from the second terminal device, wherein transmission power of the
one or more transmissions is determined based on the one or more power control parameters;
5 and transmitting the power offset to the second terminal device. In some embodiments, the
determined power offset is below a difference between a target receiving SINR and a
measured receiving SINR.
[0013] In a second aspect of the disclosure, there is provided another method
implemented at a second terminal device. The method comprises receiving, from a first
1 0 terminal device, one or more power control parameters for a transmission from the second
terminal device to the first terminal device; determining a transmission power for the
transmission based on the one or more power control parameters; and performing the
transmission to the first terminal device according to the determined transmission power.
[0014] In some embodiments, the one or more power control parameters may include at
15 least one of: a power adjustment value relative to a reference power level, a base power level,
and a pathloss compensation factor. In some embodiments, the reference power level may
comprise a transmission power determined for the transmission based on one or more of: a
power control parameter configured by a base station or preconfigured, a pathloss between
the second terminal device and the base station, and a power compensation associated with a
20 MCS and/or a QoS level of the transmission.
[0015] In some embodiments, the one or more power control parameters may include
the power adjustment value, and wherein determining the transmission power may comprise:
determining a candidate transmission power based on a sum of the power adjustment value
and the reference power level; and determine the transmission power as a minimum one of
25 the candidate transmission power and a transmission power limit.
[0016] In some embodiments, the method may further comprise: recetvmg a power
offset for the transmission from the first terminal device; and wherein determining the
transmission power may comprise: detennining an averaged transmission power of one or
more transmissions performed with a transmission power detennined based on the one or
30 more power control parameters; detennining a candidate transmission power based on a sum
of the power offset and the averaged transmission power; and determining the transmission
power as a minimum one of a transmission power limit and the candidate transmission
power.
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[0017] In some embodiments, the one or more power control parameters may include
the base power level and the pathloss compensation factor, and wherein determining the
transmission power may comprise: detennining a candidate transmission power based on a
sum of the base power level and a pathloss between the first terminal device and the second
5 terminal device weighted by the pathloss compensation factor; and determining the
transmission power as a minimum one of a transmission power limit and the candidate
transmission power. In some embodiments, the method may further comprise: receiving a
power offset for the transmission from the first terminal device; and wherein determining the
candidate transmission power may comprise: determining the candidate transmission power
10 further based on the power offset. In some embodiments, determining the candidate
transmission power may comprise: determining the candidate transmission power further
based on an accumulative value of previous power offsets received from the first terminal
device.
[0018] In some embodiments, determining a candidate transmission power may
15 compnse: determining the candidate transmission power further based on a power
compensation associated with a MCS and/or a QoS level of the transmission.
[0019] In some embodiments, the transmission power limit may be set to one of: the
reference power level, a first maximum transmission power for a resource where the
transmission occurs; a second maximum transmission power for a power class associated
20 with the second terminal device; and a third maximum transmission power obtained by
subtracting, from the first maximum transmission power or the second maximum
transmission power, a transmission power reserved for a uplink transmission from the second
terminal device to a base station to be perfonned simultaneously with the transmission from
the second terminal device to the first terminal device. In some embodiments, the uplink
25 transmission may include one or more of: a physical uplink control channel (PUCCH)
transmission, and a physical uplink shared channel (PUSCH) transmission.
[0020] In some embodiments, the transmission power limit may be set to one of the first
maximum transmission power, the second maximum transmission power and the third
maximum transmission power, if a QoS level of the transmission is higher than a threshold;
30 and the transmission power limit may be set to the reference power level, if the QoS level of
the transmission is lower than the threshold.
[0021] In some embodiments, the transmission power limit may be set to one of the first
maximum transmission power, the second maximum transmission power and the third
maximum transmission power, if the second terminal device is out of a coverage of a base
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station; and set to the reference power level, if the second tenninal device is in the coverage
of the base station.
[0022] In some embodiments, performing the transmission to the first terminal device
according to the determined transmission power may comprise: determining whether a total
5 transmission power of the transmission and a further transmission to be performed
simultaneously with the transmission exceeds a power threshold; in response to the total
transmission power exceeding the power threshold, reducing the determined transmission
power for the transmission; and performing the transmission to the first terminal device
according to the reduced transmission power.
10 [0023] In some embodiments, performing the transmission to the first tenninal device
according to the determined transmission power may comprise: determining whether a total
transmission power of the transmission and a further transmission to be performed
simultaneously with the transmission exceeds a power threshold; in response to the total
transmission power exceeding the power threshold, cancelling the transmission to the first
15 terminal device.
[0024] In some embodiments, the method may further comprise: reporting a power
headroom (PHR) for at least one of an uplink transmission and a sidelink transmission to a
base station.

WHAT IS CLAIMED IS:
1. A method implemented m a first terminal device m a wireless communication
system, comprising:
5 determining one or more power control parameters for a transmission from a second
tenninal device to the first terminal device;
transmitting the one or more power control parameters to the second terminal device;
and
receiVmg the transmission from the second terminal device, the transmission being
10 controlled based on the one or more power control parameters.
2. The method of Claim 1, wherein the one or more power control parameters include at
least one of:
a power adjustment value relative to a reference power level,
15 a base power level, and
a pathless compensation factor.
3. The method of Claim 2, wherein the reference power level comprises a transmission
power determined for the transmission based on one or more of:
20 a power control parameter configured by a base station or pre-configured,
a pathless between the second terminal device and the base station, and
a power compensation associated with a modulation and coding scheme, MCS,
and/or a quality of service, QoS, level of the transmission.
25 4. The method of Claim 2, wherein determining one or more power control parameters
compnses:
detennining the power adjustment value by comparing a measured performance metric
to a target performance metric.
30 5. The method of Claim 4, wherein the perfonnance metric compnses a signal to
interference and noise power ratio, SINR.
6. The method of Claim 5, further comprising:
30
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determining an averaged receiving SINR based on one or more transmissions from the
second device to obtain the measured performance metric, wherein transmission power of the
one or more transmissions is determined based on at least one of:
a power control parameter configured by a base station or pre-configured,
a pathloss between the second terminal device and the base station, and
a power compensation associated with a modulation and coding scheme, MCS,
and/or a quality of service, QoS, level of the transmission.
7. The method of Claim 6, wherein determining the averaged receiving SINR based on
10 the one or more transmissions from the second device comprises:
obtaining an estimated receiving SINR for each of the one or more transmissions; and
determining an averaged value of the estimated receiving SINRs as the averaged
receiving SINR.
15 8. The method of Claim 6, wherein obtaining the estimated receiving SINR for each of
the one or more transmissions comprises:
obtaining the estimated receiving SINR by removing power compensation associated
with a MCS and/or a QoS level for each of the one or more transmissions.
20 9. The method of Claim 2, wherein determining one or more power control parameters
25
compnses:
determining the base power level and the pathloss compensation factor based on a target
receiving signal to interference and noise power ratio, SINR, and a pathloss between the first
terminal device and the second terminal device.
10. The method of Claim 9, wherein the determined the base power level and the
pathloss compensation factor satisfies a restriction that a receiving power at the first tenninal
device is not larger than a target receiving power.
30 11. The method of Claim 1, further comprising:
determining a power offset for a further transmission from the second terminal device
based on one or more transmissions received from the second terminal device, wherein
transmission power of the one or more transmissions is detennined based on the one or more
power control parameters; and
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transmitting the power offset to the second terminal device.
12. The method of Claim 11, wherein the determined power offset is below a difference
between a target receiving signal to interference and noise power ratio, SINR, and a measured
5 receiving SINR.
13. A method implemented in a second tenninal device in a wireless communication
system, comprising:
receiving, from a first terminal device, one or more power control parameters for a
1 0 transmission from the second terminal device to the first terminal device;
15
determining a transmission power for the transmission based on the one or more power
control parameters; and
performing the transmission to the first terminal device according to the determined
transmission power.
14. The method ofC1aim 13, wherein the one or more power control parameters include
at least one of:
a power adjustment value relative to a reference power level,
a base power level, and
20 a pathloss compensation factor.
25
15. The method of Claim 14, wherein the reference power level compnses a
transmission power determined for the transmission based on one or more of:
a power control parameter configured by a base station or pre-configured,
a pathloss between the second tenninal device and the base station, and
a power compensation associated with a modulation and coding scheme, MCS,
and/or a quality of service, QoS, level of the transmission.
16. The method of Claim 14, wherein the one or more power control parameters include
30 the power adjustment value, and wherein determining the transmission power comprises:
determining a candidate transmission power based on a sum of the power
adjustment value and the reference power level; and
determining the transmission power as a m1mmum one of the candidate
transmission power and a transmission power limit.
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17. The method of Claim 14, further comprising:
receiving a power offset for the transmission from the first terminal device; and
wherein determining the transmission power comprises:
detennining an averaged transmission power of one or more transmissions
performed with a transmission power determined based on the one or more power
control parameters;
determining a candidate transmission power based on a sum of the power offset and
the averaged transmission power; and
1 0 determining the transmission power as a minimum one of a transmission power
limit and the candidate transmission power.
18 The method of Claim 14, wherein the one or more power control parameters include
the base power level and the pathloss compensation factor, and
15 wherein determining the transmission power comprises:
determining a candidate transmission power based on a sum of the base power level
and a pathloss between the first terminal device and the second tenninal device weighted
by the pathloss compensation factor; and
determining the transmission power as a minimum one of a transmission power
20 limit and the candidate transmission power.
19. The method of Claim 18, further comprising:
receiving a power offset for the transmission from the first terminal device; and
wherein detennining the candidate transmission power comprises:
25 detennining the candidate transmission power further based on the power offset.
20. The method of Claim 19, wherein determining the candidate transmission power
compnses:
determining the candidate transmission power further based on an accumulative
30 value of previous power offsets received from the first tenninal device.
21. The method of any of Claims 16 to 20, wherein determining a candidate
transmission power comprises:
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detennining the candidate transmission power further based on a power compensation
associated with a modulation and coding scheme, MCS, and/or a quality of service, QoS,
level of the transmission.
5 22. The method of any of Claims 16 to 20, wherein the transmission power limit is set to
one of:
the reference power level,
a first maximum transmission power for a resource where the transmission occurs;
a second maximum transmission power for a power class associated with the second
1 0 tenninal device; and
a third maximum transmission power obtained by subtracting, from the first maximum
transmission power or the second maximum transmission power, a transmission power
reserved for a uplink transmission from the second terminal device to a base station to be
performed simultaneously with the transmission from the second terminal device to the first
15 terminal device.
20
23. The method of Claim 22, wherein the uplink transmission includes one or more of:
a physical uplink control channel, PUCCH, transmission, and
a physical uplink shared channel, PUSCH, transmission.
24. The method of Claim 22, wherein:
the transmission power limit is set to one of the first maximum transmission power, the
second maximum transmission power and the third maximum transmission power, if a quality
of service, QoS, level of the transmission is higher than a threshold; and
25 the transmission power limit is set to the reference power level, if the QoS level of the
transmission is lower than the threshold.
25. The method of Claim 22, wherein:
the transmission power limit is set to one of the first maximum transmission power, the
3 0 second maximum transmission power and the third maximum transmission power, if the
second terminal device is out of a coverage of a base station; and
the transmission power limit is set to the reference power level, if the second tenninal
device is in the coverage of the base station.
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26. The method of Claim 13, wherein performing the transmission to the first terminal
device according to the determined transmission power comprises:
determining whether a total transmission power of the transmission and a further
transmission to be performed simultaneously with the transmission exceeds a power
5 threshold;
10
in response to the total transmission power exceeding the power threshold, reducing the
determined transmission power for the transmission; and
performing the transmission to the first terminal device according to the reduced
transmission power.
27. The method of Claim 13, wherein performing the transmission to the first terminal
device according to the determined transmission power comprises:
determining whether a total transmission power of the transmission and a further
transmission to be performed simultaneously with the transmission exceeds a power
15 threshold;
in response to the total transmission power exceeding the power threshold, cancelling
the transmission to the first terminal device.
28. The method of Claim 13, further comprising:
20 reporting a power headroom for at least one of a uplink transmission and a sidelink
transmission to a base station.
29. A terminal device for wireless communication, comprising:
at least one processor; and
25 at least one memory including computer program codes;
the at least one memory and the computer program codes are configured to, with the at
least one processor, cause the terminal device at least to perform the method of any of claims
1-12.
30 30. A terminal device, comprising:
at least one processor; and
at least one memory including computer program codes;
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the at least one memory and the computer program codes are configured to, with the at
least one processor, cause the terminal device at least to perform the method of any of claims
13-28.
5 31. A computer readable medium having a computer program stored thereon which,
when executed by at least one processor of a device, causes the device to carry out the
method of any of claims 1-12.
32. A computer readable medium having a computer program stored thereon which,
10 when executed by at least one processor of a device, causes the device to carry out the
method of any of claims 13-28.