Abstract:

Considering the characteristics that the dynamic spectrum and nodes have different channels available in cognitive radio network，if a cognitive node has no available channel，it has to quit the multicast group in the multicast environment.According to this phenomenon，this paper proposed a method to structure the key distribution tree that is suitable for cognitive radio network multicast environment，using the number of non-available channels as the weight of leaf nodes.The nodes with more non-available channels are in the higher part of the tree and the nodes with less non-available channels are in the lower part of the tree.It is proofed that the average cost of re-keying and the number of keys held by each user are minimal.

Key words: cognitive radio network, multicast, key management, Huffman tree