Method for operating femtocell in wireless communication system

Abstract

A method for operating a femtocell in a wireless communication system comprises the steps of: triggering the switching from the operation mode for providing a service to closed subscriber group (CSG) terminals which belong to a specific terminal group and to non-CSG terminals which do not belong to the specific terminal group, to the operation mode for providing the service only to said CSG terminals; and commanding said non-CSG terminals to change the operation mode, and carrying out a handover. The method of the present invention improves efficiency of femtocell operation, and reduces restrictions on terminals disposed in the vicinity of the femtocell. The method of the present invention can utilize the unused frequency range of the femtocell, thereby providing a service with a high data ratio.

1 . A method of operating a closed subscriber group (CSG) femto-cell, the method comprising:
 obtaining relevant information to change an operational mode of the CSG femto-cell; and   changing the operational mode of the CGS femto-cell based on the relevant information,   wherein the CSG femto-cell enters a low duty mode when no UE is in a service range of the CSG femto-cell, and the CSG femto-cell in the low duty mode wakes up at predetermined intervals, and   wherein the CSG femto-cell lowers a downlink transmit power of the CSG femto-cell if the CSG femto-cell is determined to be a cell causing interference to at least one UE based on a signal strength measurement obtained from the at least one UE.   
     
     
         2 . The method of  claim 1 , wherein the signal strength measurement is obtained by a serving base station of the at least one UE and delivered to the CSG femto-cell. 
     
     
         3 . The method of  claim 1 , wherein the signal strength measurement is directly obtained by the CSG femto-cell. 
     
     
         4 . The method of  claim 1 , wherein the CSG femto-cell communicates with a neighbor network entity to mitigate interference caused by the neighbor network entity. 
     
     
         5 . The method of  claim 1 , wherein the CSG femto-cell further enters the low duty mode when all UE attached to the CSG femto-cell are in an idle mode. 
     
     
         6 . The method of  claim 1 , wherein the low duty mode consists of an available interval and an unavailable interval. 
     
     
         7 . The method of  claim 1 , wherein the CSG femto-cell enters an active mode when the CSG femto-cell receives a request message requesting a mode transition to the active mode. 
     
     
         8 . The method of  claim 7 , wherein the request message is transmitted to the CSG femto-cell when a UE communicating with a neighbor cell is requested to handover toward the CSG femto-cell. 
     
     
         9 . A network entity for operating a closed subscriber group (CSG) femto-cell comprising:
 a radio frequency (RF) unit transmitting and receiving signals; and   a processor coupled to the RF unit and configured to:   obtain relevant information to change an operational mode of the CSG femto-cell; and   change the operational mode of the CGS femto-cell based on the relevant information,   wherein the CSG femto-cell enters a low duty mode when no UE is in a service range of the CSG femto-cell, and the CSG femto-cell in the low duty mode wakes up at predetermined intervals, and   wherein the CSG femto-cell lowers a downlink transmit power of the CSG femto-cell if the CSG femto-cell is determined to be a cell causing interference to at least one UE based on a signal strength measurement obtained from the at least one UE.   
     
     
         10 . The network entity of  claim 9 , wherein the signal strength measurement is obtained by a serving base station of the at least one UE and delivered to the CSG femto-cell. 
     
     
         11 . The network entity of  claim 9 , wherein the signal strength measurement is directly obtained by the CSG femto-cell. 
     
     
         12 . The network entity of  claim 9 , wherein the CSG femto-cell communicates with a neighbor network entity to mitigate interference caused by the neighbor network entity. 
     
     
         13 . The network entity of  claim 9 , wherein the CSG femto-cell further enters the low duty mode when all UE attached to the CSG femto-cell are in an idle mode. 
     
     
         14 . The network entity of  claim 9 , wherein the low duty mode consists of an available interval and an unavailable interval. 
     
     
         15 . The network entity of  claim 9 , wherein the CSG femto-cell enters an active mode when the CSG femto-cell receives a request message requesting a mode transition to the active mode. 
     
     
         16 . The network entity of  claim 15 , wherein the request message is transmitted to the CSG femto-cell when a UE communicating with a neighbor cell is requested to handover toward the CSG femto-cell.