Biblio
It is hard to set up an end-to-end connection between source and destination in Opportunistic Networks, due to dynamic network topology and the lack of infrastructure. Instead, the store-carry-forward mechanism is used to achieve communication. Namely, communication in Opportunistic Networks relies on the cooperation among nodes. Correspondingly, Opportunistic Networks have some issues like long delays, packet loss and so on, which lead to many challenges in Opportunistic Networks. However, malicious nodes do not follow the routing rules, or refuse to cooperate with benign nodes. Some misbehaviors like black-hole attack, gray-hole attack may arbitrarily bloat their delivery competency to intercept and drop data. Selfishness in Opportunistic Networks will also drop some data from other nodes. These misbehaviors will seriously affect network performance like the delivery success ratio. In this paper, we design a Trust-based Routing Protocol (TRP), combined with various utility algorithms, to more comprehensively evaluate the competency of a candidate node and effectively reduce negative effects by malicious nodes. In simulation, we compare TRP with other protocols, and shows that our protocol is effective for misbehaviors.
Distribution system security region (DSSR) has been widely used to analyze the distribution system operation security. This paper innovatively defines the scale of DSSR, namely the number of boundary constraints and variables of all operational constraints, analyzes and puts forward the corresponding evaluation method. Firstly, the influence of the number of security boundary constraints and variables on the scale of DSSR is analyzed. The factors that mainly influence the scale are found, such as the number of transformers, feeders, as well as sectionalizing switches, and feeder contacts modes between transformers. Secondly, a matrix representing the relations among transformers in distribution system is defined to reflect the characteristics of network's structure, while an algorithm of the scale of DSSR based on transformers connection relationship matrix is proposed, which avoids the trouble of listing security region constraints. Finally, the proposed method is applied in a test system to confirm the effectiveness of the concepts and methods. It provides the necessary foundation for DSSR theory as well as safety analysis.