Wireless communication network system.

A wireless communication network system includes a communication controller, and a plurality of terminal devices which can communicate with the communication controller by wireless. The communication controller includes a first section for detecting absence of a received signal from any of the terminal devices, and a second section responsive to an output signal of the first section for periodically generating a nonbusy signal, which can be discriminated from another signal transmitted from the communication controller, in the absence of the received signal. Each of the terminal devices includes a third section for detecting the nonbusy signal, and a fourth section responsive to an output signal of the third section for permitting transmission from the terminal device after the nonbusy signal is received by the third section.