In order to build large-scale RFID applications, it is necessary to establish public RFID service infrastructure, the essential task is to build efficient and secure RFID code resolution network. Aiming at alleviating the problems in load balancing, single node failure tolerance and security of resolution network, based on related standards and research works, a hierarchical P2P based RFID code resolution network structure is proposed, k-Nearest Neighbor storing and hierarchical querying mechanism are presented in static resolution, secondary indexing and hierarchical querying mechanism are presented in dynamic resolution, double random number based entity and message authentication mechanism is given for the correctness of resolution service. Based on modified Kademlia, RFID code resolution services and related security mechanism are implemented. In experiments, the availability, load balancing and single node failure tolerance of our resolution network are verified.
Based on the routing protocol of Kademlia network and the characteristics of semantics-based publish/subscribe systems, a new type of routing protocol for semantics-based publish/subscribe systems is designed, which is called intersection concept based routing protocol (ICBRP). In ICBRP, user`s subscriptions are classified by minimal intersection concepts and one type of subscriptions is forwarded to the event brokers taking charge of this type. Since event publishing is also based on intersection concepts, every event can be forwarded to the brokers storing the subscriptions which the event may be matched with, and the events is able to be forwarded to all the interested subscribers. The result of simulation experiments shows that the performance of our routing protocol can satisfy the need of application.
Aiming at the problems that sparrow search algorithm is easy to fall into local optimum, slow convergence speed and insufficient convergence accuracy, an improved sparrow search algorithm (ISSA) with weighted mutation and neighborhood perturbation is proposed. Improve the follower position update formula, and add the weighted mutation differential evolution algorithm to maintain the population diversity and balance the global exploration and local development ability of the algorithm. Combining attack with reverse search and variable spiral position update, the algorithm perturbs the individual position around the optimal neighborhood, jumps out of the local optimization, and improves the convergence speed and accuracy of the algorithm. The performance of the improved algorithm is tested on 12 benchmark functions. The experimental results show that the improved algorithm has better optimization accuracy, convergence performance and stability.
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