Wireless communications system, base station, and mobile station

A base station for performing a packet communication between a plurality of mobile stations in a wireless communications system, the base station comprising:

• a processor coupled to memory storing instruction which when executed by the processor to notify a specific mobile station among the plurality of mobile stations of information of a plurality of wireless frames allowing the start of a packet transmission toward the specific mobile station, so as to have the specific mobile station:
• determine one or more first frames which are frames determined as being with the possibility of the packet transmission which are positioned at start frames which are notified as allowing the start of packet transmission and the packet transmission is actually carried out,
• detect as to whether or not a packet transmission is actually carried out at the first frames,
• determine one or more second frames, consecutively following the first frames, determined as being with the possibility of a packet transmission, when it is detected that a packet transmission is actually carried out at the first frames, a number of the second frames differs depending on a number of frames with the possibility of receiving packets continuously,
• determine one or more third frames consecutively following the second frames, when it is detected that a packet transmission is not carried out at the second frames, and the third frames being determined as being without the possibility of a packet transmission, and wherein a number of the third frames is determined according to a number of the first frames and the number of the second frames, and a total number of frames of the number of the first frames, the number of the second frames, and the number of the third frames is constant, and
• shift to a peripheral cell detection mode at the third frames.