Abstract: Disclosed are a base station and mobile station to adaptively control a bandwidth of a channel. The base station includes a state information recognition unit to recognize neighboring-state information related with a traffic load of at least one neighboring network adjacent to a target network, a control state information transmitting unit to transmit control state information related with the controlled bandwidth of the target channel to mobile stations of the target network, and a bandwidth control unit to control a bandwidth of a target channel used in the target network according to a bandwidth of a channel used in the neighboring network based on the neighboring-state information.

Abstract: In retransmitting data at high speed by a PHY layer in a mobile communication system, when data to be transmitted to the receiver is received from the MAC layer of the transmitter, the PHY layer of the transmitter transmits the data to the PHY layer of the receiver, receives first information representing normal reception or abnormal reception of the data from the PHY layer of the receiver, notifies the MAC layer of the transmitter of the normal reception of the data when the first information represents the normal reception, and retransmits the data to the PHY layer of the receiver when the first information represents the abnormal reception.

Abstract: Disclosed are a base station and mobile station to adaptively control a bandwidth of a channel. The base station includes a state information recognition unit to recognize neighboring-state information related with a traffic load of at least one neighboring network adjacent to a target network, a control state information transmitting unit to transmit control state information related with the controlled bandwidth of the target channel to mobile stations of the target network, and a bandwidth control unit to control a bandwidth of a target channel used in the target network according to a bandwidth of a channel used in the neighboring network based on the neighboring-state information.

Abstract: A cognitive radio terminal device. The cognitive radio terminal device comprises an available radio resource determination unit to determine an available radio resource from among up-link radio resources assigned to an up-link communication in a primary network, and an ad hoc communication performing unit to perform an ad hoc communication in a secondary network by using the available radio resource.

Abstract: In retransmitting data at high speed by a PHY layer in a mobile communication system, when data to be transmitted to the receiver is received from the MAC layer of the transmitter, the PHY layer of the transmitter transmits the data to the PHY layer of the receiver, receives first information representing normal reception or abnormal reception of the data from the PHY layer of the receiver, notifies the MAC layer of the transmitter of the normal reception of the data when the first information represents the normal reception, and retransmits the data to the PHY layer of the receiver when the first information represents the abnormal reception.