Cache management method for transmitting real-time streaming media in opportunistic networks based on community networks

Opportunistic networks are often used for delivering messages in the social networks. This paper proposes a community networks based cache management method (CNCM) which is applied to transmit the mobile real-time streaming media in community networks. This method includes the strategy of message discarding and the policy of message forwarding. The strategy of message discarding is that: it firstly sets up a threshold which is based on the relationship of nodes in the community---namely the clustering coefficient, and then judges whether the ratio η (which is the ratio of the number of messages transmitted to own community nodes to the number of all messages in the buffer) is greater than the threshold, finally selects the appropriate buffer replacement algorithm to drop messages. The policy of message forwarding is that: a node judges whether a message's transmission time is less than the communication time of the two nodes and decides which messages should be transmitted. The simulation results show that the CNCM outperforms existing ones in terms of the delivery rate, the average overhead ratio, the average delay.