Method and apparatus for power control
Embodiments of the present disclosure provide method and apparatus for changing radio access technology. A method performed by a network device comprises obtaining channel estimation information of a terminal device; determining an uplink power value according to the channel estimation information and a number of antennas to be used; and transmitting the uplink power value to the terminal device periodically.
1 . A method implemented at a network node, the method comprising:
updating an initial target received power based on a number of antennas to be used, wherein the initial target received power is updated according to according to:
P
0
=
P
0
base
-
10
*
log
(
N
ant
2
)
where P 0 is an updated initial target received power,
P
0
base
is the initial target
received power, and N ant is the number of antennas to be used;
transmitting the updated initial received target power to a terminal device;
obtaining channel estimation information of the terminal device;
determining an uplink power value according to the channel estimation information and the number of antennas to be used;
transmitting the uplink power value to the terminal device periodically.
2 . The method of claim 1 , wherein obtaining the channel estimation information of the terminal device comprises obtaining the channel estimation information of the terminal device via an uplink reference signal, wherein the uplink reference signal comprises a sounding reference signal (SRS).
3 . The method of claim 1 , wherein the number of antennas to be used is configured in system information.
4 . The method of claim 1 , wherein determining uplink power value according to the channel estimation information and the number of antennas to be used comprises:
determining path loss information, interference information, and noise evaluation information according to the channel estimation information; and
determining the uplink power value according to path loss information, interference information, noise evaluation information, and the number of antennas to be used.
5 . The method of claim 4 , wherein determining the uplink power value further comprises determining interference level filtering according to:
P
i
p
n
filtered
=
(
1
-
α
)
*
P
i
p
n
filtered
+
α
*
P
i
p
n
where P ipn is an instantaneous power of interference plus noise value,
P
i
p
n
f
i
l
t
e
r
e
d
is a filtered result, and α is a filtering factor.
6 . The method of claim 5 , wherein determining the uplink power value further comprises determining a target received power according to:
P
r
x
T
g
t
=
SINR
U
L
M
o
d
+
P
i
p
n
filtered
where
P
r
x
T
g
t
is the target received power and
SINR
U
L
M
o
d
is an uplink (UL) target signal to noise ratio determined according to a Physical Uplink Shared Channel (PUSCH) received power and a modulation mode.
7 . The method of claim 6 , wherein the modulation mode comprises 256QAM, 64QAM, 16QAM, or QPSK.
8 . The method of claim 1 , wherein transmitting the uplink power value to the terminal device comprises transmitting the uplink power value to the terminal device via system block information (SIB).
9 . The method of claim 8 , wherein a period for transmitting the uplink power value is N times a period of the SIB, Nis an integer greater than or equal to 1.
10 . The method of claim 9 , wherein N is determined according to interference level.
11 . A method implemented at a terminal device, the method comprising:
receiving, from a network node, an updated initial target received power based on a number of antennas to be used, wherein the initial target received power is updated according to:
P
0
=
P
0
base
-
10
*
log
(
N
ant
2
)
where P 0 is an updated initial target received power,
P
0
base
is the initial target received power, and Non is the number of antennas to be used;
determining a preamble transmission power based on the updated initial target received power and a pathloss estimation result;
receiving an uplink power value sent from the network node periodically; and
adjusting transmitting power according to the uplink power value;
wherein the uplink power value is determined according to channel estimation information and the number of antennas to be used.
12 . The method of claim 11 , wherein the method further comprises transmitting an uplink reference signal for channel estimation, before receiving the uplink power value sent from the network node, wherein the uplink reference signal comprises a sounding reference signal (SRS).
13 . The method of claim 11 , wherein the number of antennas to be used is configured in system information.
14 . The method of claim 11 , wherein
path loss information, interference information, and noise evaluation information is determined according to the channel estimation information; and
the uplink power value is determined according to path loss information, interference information, noise evaluation information, and the number of antennas to be used.
15 . The method of claim 11 , wherein receiving the uplink power value sent from the network node comprises: receiving the uplink power value sent from the network node via system block information (SIB).
16 . The method of claim 15 , wherein a period for receiving the uplink power value is N times a period of the SIB, N is an integer greater than or equal to 1.
17 . The method of claim 16 , wherein N is determined according to interference level.
18 . A network node comprising:
a processor; and
a memory containing instructions that, when executed by the processor, cause the network node to:
update an initial target received power based on a number of antennas to be used, wherein the initial target received power is updated according to:
P
0
=
P
0
base
-
10
*
log
(
N
ant
2
)
where P 0 is an updated initial target received power,
P
0
base
is the initial target received power, and N ant is the number of antennas to be used;
transmit the updated initial received target power to a terminal device;
obtain channel estimation information of the terminal device;
determine an uplink power value according to the channel estimation information and the number of antennas to be used; and
transmit the uplink power value to the terminal device periodically.
19 . The network node of claim 18 , wherein obtaining the channel estimation information of the terminal device comprises obtaining the channel estimation information of the terminal device via an uplink reference signal.
20 . The network node of claim 18 , wherein the number of antennas to be used is configured in system information.