Research On Routing Protocol And Congestion Control In Opportunistic Networks

As a new kind of Mobile Ad hoc Networks(MANET), opportunistic network has a character that is the links between nodes are frequently broken and the entire network is usually in the disconnected state, which induce these protocols in the MANET could not be run in the opportunistic network, so the way of “store-carry-forward” is usually adopted in the node of opportunistic networks. It is important to choose an appropriate node for forwarding the message, because node needs to be carried messages during its moving. In recent years, it is found that 20% of the important node in the network finished at most 80% of the data forwarding task in the research of routing protocol, which is easy to cause the buffer of nodes congestion and impact on the performance of the entire network, so the routing protocol and congestion control in opportunistic networks has become the main content of study. The study of congestion control algorithm is expound combines the characteristics of social networks, the feature of the storage in this thesis. The main work is as follows:(1) A congestion control strategy based on the change of the nodes’ identity in opportunistic networks is proposed. The node can be divided into mild congestion, moderate congestion and severe congestion by different congestion threshold in the algorithm. The node choose the different identity from receiving node, forwarding node as well as receiving and forwarding node to participate in the forwarding process. Besides, in order to prevent the node to discard the message blindly, a replication management strategy is proposed. First of all, the message is ranking according to its own value, the nodes will choose migrate or discard the message directly according to the different congestion level of the other nodes when the nodes buffer is full. In order to verify the validity of the proposed strategy, this method combines the strategy with Epidemic algorithm, and an EpidemicCC algorithm which has the function of congestion control is proposed.(2) A congestion control algorithm based on the social awareness in opportunistic networks is proposed. When the algorithm choosing the suitable relay forwarding nodes, it will consider the direct social relationship, indirect social relationship and the receiving capability as the transfer utility, the receiving capability is the available cache of the nodes. The algorithm consider these utility value of the node and avoid forwarding to the nodes which buffer is congested. Besides, in order to prevent the node discard the message blindly, a message processing strategy based on the social awareness is proposed, the message which the utility value is the lowest will be dropped by comparing the utility value of its own messages when the receiving node congestion occurs.In order to verify the validity of the algorithm, this thesis uses the Opportunistic Networks Environment software(ONE) for simulation of congestion control algorithm. The results show that our congestion control algorithm can reduce the degree of nodes’ congestion effectively and the number of copies, and improve the efficiency of data delivery.