Patent ID: 8598985

Claim:
A communications system configured to execute data transmission between a transponder having no radio wave generating source thereof and a reader/writer, the communication system comprising: a service permission level notifier, included in the reader/writer, configured to transmit to the transponder a measurement of a service permission level of a signal received from the reader/writer by the transponder, the service permission level indicating a signal level required to be received at the transponder for permitting service acceptance by the transponder from the reader/writer, wherein the reader/writer is configured to set the service permission level and provide the service to the transponder; a measuring unit, included in the transponder, configured to measure a received signal level of the signal received from the reader/writer; and an access controller configured to determine in the transponder whether the received signal level from the reader/writer is at the service permission level to determine whether the reader/writer can read data associated with the service from the transponder and whether the reader/writer can write data associated with the service to the transponder, wherein a service entry sequence is provided in which the reader/writer notifies the transponder of a beacon frame at a predetermined time interval and the transponder returns a response frame in response to the beacon frame within a predetermined entry period after transmission of the beacon frame, the service permission level notifier notifying the transponder of a service permission level through a beacon frame to be transmitted by the reader/writer, and the access controller determining whether a received signal level of the beacon frame received by the transponder from the reader/writer is at the service permission level to determine whether the reader/writer can read data associated with the service from the transponder and whether the reader/writer can write data associated with the service to the transponder.