Distributed packet access method based on no-rate codes in cognitive radio

The invention discloses a distributed packet access method based on no-rate codes in cognitive radio. The invention transmits data among secondary users by using no-rate packet encoding, and provides a package access method suitable for distributed multicarrier cognitive radio systems. The method comprises the following steps of: 1. classifying and caching data to be transmitted; 2. selecting thesubcarrier in a random mode, wherein the access probability is the experience weighted value of the utility function value; 3. selecting the transmission packet length by predicting the arrival time of the master user; 4. carrying out the encoding packet scheduling by using a rate domain water-filling method; and 5. and constituting the complete transmission packet to complete the packet access. The method can effectively prevent inevitable packet losses in a cognitive radio system by using the no-rate packet encoding, can be effectively applied in distributed multicarrier cognitive radio systems because the secondary