Patent ID: 6625162
Filing Date: 2003-09-23
Classification: H04W

Abstract:
A data transmission apparatus comprising:a judgment circuit for judging whether or not a transmission medium is available; a transmitter for transmitting a control signal through the transmission medium to request a reception side to receive transmission data, in accordance with a judgment by said judgment circuit; and a receiver for receiving a response signal from the reception side in response to the control signal, wherein said transmitter transmits the transmission data to the reception side if the response signal is received at said receiver, and retransmits the control signal to the reception side after a random back-time if the response signal is not received at said receiver, and wherein one of first and second periods is selected as the random back-off time in accordance with a retransmission number of the control signal, and the second period is selected if the control signal is retransmitted more than a predetermined retransmission number.