In the high-speed network environment,to achieve fast and accurate packet classification is of great significance to the novel network.This paper designs and implements the Hash algorithm based on dimension decomposition(HDD) on the basis of the ideological of dimension decomposition and in combination with single step mapping and hash method.The algorithm first considers accurate packet classification,then significantly accelerates searching and improves performance by introducing a hash table for mapping between the rules and the data stream.Experimental results show that the number of average memory accesses of HDD algorithm is lower than Hierarchical Space Mapping(HSM) algorithm and Recursive Flow Classification(RFC) algorithm respectively by 86% and 60%,what’s more,HDD algorithm saves 8% of space usage than RFC algorithm when the rule number is more than 2 500.
To reduce the resource use of sensors and enhance the security of Wireless Sensor Network(WSN),a trust-based authentication scheme is proposed and it calculates the node trust by introducing the time slice,the coefficient of safety operations and the frequency of interaction.This makes it difficult for selfish nodes to masquerade as normal nodes,makes trust behavior closely related to the current node,and prevents nodes from achieving higher trust through few trades.Then through combining the identification,the password and the smart card,a user authentication scheme is designed.Before the user authenticates with the sensor node,the gateway node needs to query the trust of nodes and find the trusted node.The optimized certification scheme is used to realize the interaction among nodes,gateway nodes and user can change the password easily.The safety analysis,the performance analysis and the result of the simulation show that,compared with the previous proposed user authentication schemes,this scheme can resist replay attack,inside attack,masquerading,etc.Meanwhile,it costs little time.Thus,this scheme is suitable for WSN which has a high request for the security and performance.
In view of the current algorithm for multi-image synchronous real-time encryption has low efficiency,high complexity and cannot meet the requirements of real-time transmission problem.The selectively multi-image lossless real time encryption algorithm based on significant pixels composite matrix is proposed.All the pixels of plaintexts are permutated by introducing the Zigzag mechanism;the image pixels are divided into important pixels and unimportant pixels by defining the pixels of interest selection mechanism for getting several important pixels matrix;and the composite matrix is obtained by designing the iteration plural model.Using the singular value decomposition gets the key matrix.The cipher is formed by constructing the diffusion function to diffuse the significant pixel composite matrix.This algorithm only encrypts the image significant pixels,avoiding the diffusion of non-significant pixel,resulting in low complexity.Simulation results show that this algorithm has high security,and belongs to lossless encryption;comparison with other multi-image encryption mechanism,the encryption/decryption efficiency of this algorithm is higher to meet the requirement of real time transmission.
With the increase of the users’ input query freedom,it causes the performance that the semi-structured data retrieval method can not meet the users’ requirements.A novel semi-structured retrieval model based on the factor graph model is proposed to solve this problem.This framework incorporates term weighting,Bayesien attribute mapping and edit distance based string similarity metrics together to improve the retrieving performance.A number of queries are randomly selected from logs of a commercial search engine and manually are labeled for analysis and evaluation.Experimental results show that this model can effectively improve the retrieval performance of semi-structured data compared with Hierarchical Language Model(HLM) and Probability Retrieval Model for Semi-structured Data(PRMS),etc.
Mountainous environmental factors are complicated and changeable,the stability and reliability of radio frequency signal propagation is also severely affected.Data collection strategy based on traditional radio propagation model may not play the expected performance even fall into disuse.In view of this phenomenon,this paper proposes a Wireless Sensor Network(WSN)data acquisition system based on multi-attribute evaluation model.The architecture and working mechanism of the system is introduced.The key implementation technology of cluster head election and next routing hop selection is described.Simulation and analysis verify its performance.The results show that the system is able to measure the comprehensive evaluation indexes comprehensively,which can determine the cluster head and next routing hop scientifically and reasonably,and can better adapt to the data collection needs of mountainous orchard precision management.
Cascaded Integrator Comb(CIC)filter is always used as decimator or interpolator in broadband communication chips because of its simple construction and high efficiency.As the development of communication system and very large scale integrated circuit,chip’s integration density becomes higher,so it is important to optimize the area of CIC filter.This paper designs a CIC interpolation filter for wireless broadband radio frequency chip.The proposed design reduces the bit width of internal nodes of the filter by bit width optimization.In addition,for gain calibration,the proposed design uses Canonic Signed Digit(CSD)code multiplication cutting off the output data’s bits width,instead of two’s complement multiplication.Experimental results show that the filter optimizes the area of multipliers by 58% area reduction compared with preoptimized CIC interpolation filter.