Patent ID: 8160090

Claim:
A communication apparatus, used within a communication system, for avoiding collision of a transmission frame, transmitted by another communication apparatus in the same communication system, in a transmission line medium using a back-off process, the communication apparatus comprising: a back-off process section for performing, using a contention window, a regular back-off process which is performed at transmission of a transmission frame and a pseudo back-off process which is performed by simulating transmission of pseudo transmission frames, which are not actually transmitted, at the completion of the pseudo back-off process regardless of whether the transmission line medium remains idle at the completion of the pseudo back-off process, when the communication apparatus does not have a frame to be transmitted; a medium information obtaining section for obtaining, by the pseudo back-off process, medium information indicative of a state of the transmission line medium when the communication apparatus does not have a frame to be transmitted; and a medium state determination section for determining the state of the transmission line medium using the medium information to obtain determination information, wherein the medium information includes at least one of a trial number value of the pseudo back-off process, a contention loss number value indicative of a number of times which a pseudo transmission frame has not been transmitted, a contention win number value indicative of a number of times which the pseudo transmission frame has been transmitted, and a collision number value indicative of a number of times of collision of the pseudo transmission frame and the transmission frame in the transmission line medium.