| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a communication system, a communication apparatus and a communication method capable of easily solving a so-called hidden terminal problem caused in radio communication such as short-range communication. <P>SOLUTION: Communication apparatuses 1, 3 determine whether an electromagnetic wave of a level equal to or higher than carrier wave output suppression determining magnetic flux density TH1. When the electromagnetic wave of the level equal to or higher than the carrier wave output suppression determining magnetic flux density TH1 has not been detected, the apparatuses 1, 3 start to output an electromagnetic wave. On the contrary, to obtain data via the electromagnetic wave, a communication apparatus 2 needs an electromagnetic wave of a level equal to or higher than carrier wave output suppression determining magnetic flux density TH2 higher than the carrier wave output suppression determining magnetic flux density TH1. This system is applicable to e.g. an IC card system etc. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
