US Patent 7356018 Communication system, communication device, and communication method

A communication system including a master station communication device and multiple slave station communication devices is disclosed. The master station communication device transmits a transmission request simultaneously to the slave station communication devices. The transmission request includes identification information identifying one or more of the slave station communication devices that are authorized to transmit information and time information indicating duration of time for which the one or more of the slave station communication devices are authorized to transmit the information. The one or more of the slave station communication devices transmit the information to the master station communication device based on the transmission request transmitted from the master station communication device.