Method and apparatus of controlling uplink power for multi-cell cooperative system
A method and apparatus of controlling uplink transmit power is provided. An estimated path-loss value for each of downlink signals from a control base station and one or more neighboring base stations is calculated. A signal path-loss value by using the calculated plurality of estimated path-loss values is obtained. An open-loop power control parameter by using the signal path-loss value is obtained. Uplink power can be controlled by considering cooperative communication of a plurality of base stations in a multi-cell cooperative radio communication system.
1. A method of controlling uplink transmit power, the method comprising:
(a) calculating an estimated path-loss value for each of downlink signals from a control base station and one or more neighboring base stations;
(b) obtaining a signal path-loss value by using the calculated plurality of estimated path-loss values; and
(c) obtaining an open-loop power control parameter by using the signal path-loss value,
wherein, in operation (b), the signal path-loss is obtained based on an inter-cell cooperative communication scheme between the control base station and the neighboring base stations,
wherein the inter-cell cooperative communication scheme combines an uplink signal received by the control base station and uplink signals respectively received by the neighboring base stations,
wherein the signal path-loss value of operation (b) can be expressed by a function of a plurality of estimated path-loss values obtained in operation (a),
wherein the inter-cell cooperative communication scheme selects an uplink signal with best quality from uplink signals received by the control base station, and
wherein the signal path-loss value of operation (b) is an estimated path-loss value for a downlink signal having a smallest magnitude among signals received from the control base station and the neighboring base stations.
2. The method of claim 1 , further comprising:
providing by the control base station a list of the neighboring base stations participating in combining of the uplink signals,
wherein, in operation (a), the estimated path-loss value is calculated only for a neighboring base station included in the list.
3. The method of claim 1 , wherein the function is expressed by Equation (E-1):
PL
C
=
-
10
log
10
(
∑
n
=
C
g
n
)
,
(
E
-
1
)
where a set C comprises the control base station and the neighboring base stations, g n =10 −0.1×PL n , and PL n is an estimated path-loss value for a downlink signal of an n th neighboring base station.
4. An apparatus for controlling uplink transmit power, the apparatus comprising:
a radio frequency (RF) unit configured to transmit and receive radio signals; and
a processor connected to the RF unit and configured to:
(a) calculate an estimated path-loss value for each of downlink signals from a control base station and one or more neighboring base stations;
(b) obtain a signal path-loss value by using the calculated plurality of estimated path-loss values; and
(c) obtain an open-loop power control parameter by using the signal path-loss value,
wherein, in operation (b), the signal path-loss is obtained based on an inter-cell cooperative communication scheme between the control base station and the neighboring base stations,
wherein the inter-cell cooperative communication scheme combines an uplink signal received by the control base station and uplink signals respectively received by the neighboring base stations,
wherein the signal path-loss value of operation (b) can be expressed by a function of a plurality of estimated path-loss values obtained in operation (a),
wherein the inter-cell cooperative communication scheme selects an uplink signal with best quality from uplink signals received by the control base station, and
wherein the signal path-loss value of operation (b) is an estimated path-loss value for a downlink signal having a smallest magnitude among signals received from the control base station and the neighboring base stations.
5. The apparatus of claim 4 , further comprising:
providing by the control base station a list of the neighboring base stations participating in combining of the uplink signals,
wherein, in operation (a), the estimated path-loss value is calculated only for a neighboring base station included in the list.
6. The apparatus of claim 4 , wherein the function is expressed by Equation (E-1):
PL
C
=
-
10
log
10
(
∑
n
=
C
g
n
)
,
(
E
-
1
)
where a set C comprises the control base station and the neighboring base stations, g n =10 −0.1×PL n , and PL n is an estimated path-loss value for a downlink signal of an n th neighboring base station.