In this paper,a novel simple detector is designed to remove the intra-signal interference in high efficiency differential chaos shift keying(HE-DCSK)modulation scheme.With the help of data bit estimated before correlation detection,this new detector could remove the modulated chaotic segment that would form intra-signal interference component in the correlator output from every received information-bearing signal in HE-DCSK,leading to greatly and effectively improved system bit error rate(BER)performance.The effectiveness of this proposed detector is studied analytically based on the numerical integration method and evaluated by computer simulation in additive-white-Gaussian-noise(AWGN)channel.Simulation results reveal that the proposed detector can dramatically improve the overall BER performance of HE-DCSK even at relatively low signal noise ratio(SNR)levels.
In this paper,based on coupled network generated by chaotic logarithmic map,a novel algorithm for constructing hash functions is proposed,which can transform messages and can establish a mapping from the transformed messages to the coupled matrix of the network.The network model is carefully designed to ensure the network dynamics to be chaotic.Through the chaotic iterations of the network,quantization and exclusive-or (XOR) operations,the algorithm can construct hash value with arbitrary length.It is shown by simulations that the algorithm is extremely sensitive to the initial values and the coupled matrix of the network,and has excellent performance in one-way,confusion and diffusion,and collision resistance.
In radio frequency identification(RFID) systems,one of the most widely used anti-collision algorithms is the dynamic framed slotted ALOHA(DFSA)algorithm which usually uses two methods,one is tag estimation method (TEM) which estimates the number of tags around the reader,and the other is dynamic slot allocation (DSA) method which is the method to dynamically allocate the frame size according to the number of tags.DFSA can achieve optimal system performance when the frame size is equal to the number of tags.As the number of tags becomes large,DFSA is not practical to increase the frame size infinitely,thus the application of DFSA algorithm is limited.In this paper a TEM method and a DSA method are proposed from two novel aspects respectively in order to use DFSA algorithm more effectively,and the analysis and comparison are given subsequently.Meanwhile,the improved DFSA algorithm is proposed to solve the problem of DFSA algorithm.When the number of tags is large,if the improved DFSA algorithm is applied,the system efficiency that can be attained is not less than 50%.
In this article,a modified susceptible-infected-removed(SIR) model is proposed to study the influence of diversity of node anti-attack abilities on the threshold of propagation in scale-free networks.In particular,a vulnerability function related to node degree is introduced into the model to describe the diversity of a node anti-attack ability.Analytical results are derived using the mean-field theory and it is observed that the diversity of anti-attack of nodes in scale-free networks can increase effectively the threshold of epidemic propagation.The simulation results agree with the analytical results.The results show that the vulnerability functions can help adopt appropriate immunization strategies.
