| 摘要 |
PROBLEM TO BE SOLVED: To provide a short-distance radio data communication from a central control point (interrogator) to many inexpensive end points (tag). SOLUTION: A tag 105 uses a modulation back-scatter method for a communication from the tag 105 to an interrogator 103. A new down-link protocol is used for data transmission from the interrogator 103 to the tag 105 and a new up-link protocol is used for data transmission from the tag 105 to the interrogator 103. Either protocol resends messages which are neither confirmed nor answered at random by using back-off/retry algorithm. The transmission capacity from the tag 105 to the interrogator 103 is improved more by using up-link subcarrier frequency-division multiplexing. In concrete, the tag 105 includes a sensor for temperature, smoke, or living body information and sends its output to the interrogator 103 with an up-link information signal.
|
