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Communications system and communications apparatus

  • US 8,598,985 B2
  • Filed: 04/30/2008
  • Issued: 12/03/2013
  • Est. Priority Date: 05/23/2007
  • Status: Active Grant
First Claim
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1. 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, andthe 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.

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