Communication system

Abstract

In a communication system of the present invention, a HeNB measures interference in Step ST 41 in an energy saving mode. When judging to have detected the interference by a UE during communication with an eNB in Step ST 42, the HeNB cancels the energy saving mode and moves to a normal mode in Step ST 43 and starts issuing a pilot signal in Step ST 44. When the UE judges to have detected the pilot signal in Step ST 23 and reports the judgment results to the eNB in Step ST 24, in Steps ST 25 to ST 32, a handover process from the eNB to the HeNB is performed for the UE.

1 . (canceled) 
     
     
         2 . A communication system, which comprises a communication terminal device, a large-scale base station device that configures a large-scale cell having a relatively large range in which the large-scale base station device is configured to perform radio communication with the communication terminal device, and a small-scale base station device that configures a small-scale cell having a relatively small range in which the small-scale base station device is configured to perform the radio communication, the small-scale cell being installed in the large-scale cell, wherein
 the small-scale base station device has two operation modes of a normal mode and an energy saving mode and is capable of shifting from the normal mode to the energy saving mode and shifting from the energy saving mode to the normal mode, the small-scale base station device performing a transmission operation for a downlink transmission signal to be transmitted to the communication terminal device and a reception operation for an uplink transmission signal transmitted from the communication terminal device in the normal mode, the small-scale base station device stopping at least the transmission operation in the energy saving mode,   the small-scale base station device is configured to control switching between the normal mode and the energy saving mode based on a mode of access to the small-scale base station device and an energy saving policy predetermined per access mode.   
     
     
         3 . The communication system according to  claim 2 , wherein
 the energy saving policy is predetermined based not only on the access mode but also on a status of a neighbor cell,   the small-scale base station device is configured to control switching between the normal mode and the energy saving mode based on the mode of access to the small-scale base station device, the status of the neighbor cell of the small-scale base station device, and the energy saving policy.   
     
     
         4 . The communication system according to  claim 2 , wherein
 the small-scale base station device is configured to exchange information on mode shift with other node when shifting from the normal mode to the energy saving mode or when shifting from the energy saving mode to the normal mode.   
     
     
         5 . A base station device used, as a small-scale base station device, in a communication system, which comprises a communication terminal device, a large-scale base station device that configures a large-scale cell having a relatively large range in which the large-scale base station device is configured to perform radio communication with the communication terminal device, and the small-scale base station device that configures a small-scale cell having a relatively small range in which the small-scale base station device is configured to perform the radio communication, the small-scale cell being installed in the large-scale cell, wherein
 the base station device has two operation modes of a normal mode and an energy saving mode and is capable of shifting from the normal mode to the energy saving mode and shifting from the energy saving mode to the normal mode, the base station device performing a transmission operation for a downlink transmission signal to be transmitted to the communication terminal device and a reception operation for an uplink transmission signal transmitted from the communication terminal device in the normal mode, the base station device stopping at least the transmission operation in the energy saving mode,   the base station device is configured to control switching between the normal mode and the energy saving mode based on a mode of access to the base station device and an energy saving policy predetermined per access mode.