Patent ID: 6898196

Claim:
A mobile radio communication system, comprising: a first communication system configured to employ a code division multiple access method, the first communications system including a transmitter configured to transmit a first frame having a predetermined number of slots and having a first frame-length, at every first transmission period which is defined as a period required to transmit a first specified number of the first frames, and a receiver configured to receive the frame transmitted by the transmitter; and a second communication system configured to transmit a second frame having a second frame-length, and to transmit the second frame at a second transmission period which is defined as a period required to transmit a second specified number of the second frames and not an integer-times of the first transmission period, the second communication system coexisting with the first communication system, wherein the transmitter in the first communication system is configured to place a plurality of idle periods in the first transmission period, to determine an interval of the plurality of idle periods for each of the predetermined number of slots such that an interval between an idle period and one of other idle periods equals to an odd-number times of a value obtained by dividing the second frame-length by an even number, and to transmit the first frames including the idle periods which are placed at the determined interval to the receiver in the first communication system, and the receiver in the first communication system is configured to observe a control data transmission channel in the second communication system during the idle periods.