The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60673-2
Based on the fractional discrete cosine transform (DCT) via polynomial interpolation (PI-FrDCT) and the dependent scrambling and diffusion (DSD), an image encryption algorithm is proposed. Under certain conditions, the introduction of PI-FrDCT reduces computational complexity compared with fractional DCT (FrDCT). By using a sigmoid function, the encrypted results are limited within a range from 0 to 255. The real-valued output of PI-FrDCT is beneficial to the storage, display and transmission of the cipher-text. During the stage of confusion and diffusion, the values of all PI-FrDCT coefficients change simultaneously as their locations are replaced. DSD enhances the scrambling and diffusion level of encrypted images and provides nonlinearity to the encryption system. Simulation results demonstrate that the proposed encryption algorithm is feasible, effective and secure.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60674-4
Machine learning has a powerful potential for performing the template attack (TA) of cryptographic device. To improve the accuracy and time consuming of electromagnetic template attack (ETA), a multi-class directed acyclic graph support vector machine (DAGSVM) method is proposed to predict the Hamming weight of the key. The method needs to generate K(K 1)/2 binary support vector machine (SVM) classifiers and realizes the K-class prediction using a rooted binary directed acyclic graph (DAG) testing model. Further, particle swarm optimization (PSO) is used for optimal selection of DAGSVM model parameters to improve the performance of DAGSVM. By exploiting the electromagnetic emanations captured while a chip was implementing the RC4 algorithm in software, the computation complexity and performance of several multi-class machine learning methods, such as DAGSVM, one-versus-one (OVO)SVM, one-versus-all (OVA)SVM, Probabilistic neural networks (PNN), K-means clustering and fuzzy neural network (FNN) are investigated. In the same scenario, the highest classification accuracy of Hamming weight for the key reached 100%, 95.33%, 85%, 74%, 49.67% and 38% for DAGSVM, OVOSVM, OVASVM, PNN, K-means and FNN, respectively. The experiment results demonstrate the proposed model performs higher predictive accuracy and faster convergence speed.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi：
Algebraic immunity is an important cryptographic property of Boolean functions. The notion of algebraic immunity of Boolean functions has been generalized in several ways to vector-valued functions over arbitrary finite fields. In this paper, the results of Ref.  are generalized to arbitrary finite fields. We obtain vector-valued functions over arbitrary finite fields such that their algebraic immunities can reach the upper bounds. Furthermore, all the component functions, together with their some nonzero linear combinations, of vector-valued Boolean functions achieved by this construction have optimal algebraic immunities simultaneously.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60676-8
In vehicular ad hoc network (VANET), misbehaviors of internal nodes, such as discarding packets, may lead to a rapid decline in packet delivery ratio. To solve this problem, an improvement of greedy perimeter stateless routing (GPSR) protocol is presented. In the new protocol, trustworthiness is considered in the route selection process. The trustworthiness is measured by an objective trust model based on the subjective trust model DyTrust. And the reputation value which reflects the trustworthiness of each node is calculated and broadcasted by the intersection nodes. Specially, besides resisting the packet-discarding behavior of selfish nodes, this protocol also includes a location detection process to resist the location-faking behavior of malicious nodes. As a result, the selfish nodes and the malicious nodes can be excluded from the network. In addition, compared with improved GPSR protocol, the presented one is able to resist one kind of reputation-faking attack and has better performance in simulation.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60677-X
Inventory inaccuracy has great influence on the supply chain performance and it has attracted much attention of large numbers of researchers. This paper mainly studies the robust multi-period inventory inaccuracy problem by attaching radio frequency identification (RFID) technology. In particular, the typical retailer-supplier flexible commitment (RSFC) problem is considered to cope with the uncertain environment. After modeling, robust optimization (RO) and the affinely adjustable robust counterpart (AARC) methodology are applied to solve the model. Finally, this paper uses a numerical example for the analysis of how RFID technology can be exploited in supply chain, and the effect of demand uncertainty on the systems. The results highlight the importance of inventory availability related rates and variable uncertainty in determining the profitability of RFID adoption, which can provide managerial guidelines to supply chain firms.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60678-1
An ultra-thin and broadband absorber which consists of periodic rings with gaps is proposed in this paper. The periodic rings are printed on the middle metallic layers in a four-layer substrate of total thickness is only 3.4 mm. Simulation results, which are gotten by using finite element method (FEM) and finite-difference time-domain (FDTD), show that the absorption is higher than 90% cover the frequencies range from 7.8 GHz to 22.2 GHz. The measurement results of the absorption agree with simulated ones very well. We also discuss the working mechanism according to the anti-reflection theory in the paper.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60679-3
Sequence sets with low correlation have very important applications in modern communication systems. As in quasi-synchronous code-division multiple access (QS-CDMA) system, sequence sets with low correlation zone (LCZ) perform better than other well-known sequence sets. Furthermore, binary or quaternary sequence sets are preferred because of their easy implementation. In this paper, based on the inverse Gray mapping and special binary sequence pairs, new quaternary LCZ sequence sets were constructed. In the LCZ, the maximum of the nontrivial autocorrelation and crosscorrelation values is 1 which show that the QS-CDMA system used the new sequences sets can control the interference in a very low level.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60680-X
We have studied the effects of nearby NaCl solution on the performance of ultra high frequency (UHF) radio frequency identification (RFID) tags, using simulations and measurements. The main reason for the decrease of read range in proximity to NaCl solution is the antenna gain penalty. The boundary conditions near the surface reduce antenna efficiency and antenna gain. With the conductivity of the NaCl solution increasing, the read range of the RFID system decreases. A theoretical formula is proposed for the read range to calculate the material losses of tag antenna. The formula establishes relationship between conductivity and read range of RFID system. The maximum read range is also calculated theoretically with simulation software. In addition, we develop an experimental measurement technique to certify the feasibility of the derived formula, which involves a dynamic measurement system. Consequently, the experimental results are found to be in good agreement with theoretical data.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60681-1
A power and subcarrier assignment algorithm is proposed in this paper for maximizing the energy efficiency in the single-relay multi-users orthogonal-frequency-division -multiplexing (OFDM) systems. Under the constraints of maximum total power and minimum transmission rate, we formulate a joint optimization scheme for subcarrier pairing and power allocation to maximize the energy efficiency. The Dinkelbach’s method is used to depress the complexity and to transform the problem to a linear programming, then we use the dual decomposition approach solve the problem. In the premise of the system transmission rate, this algorithm uses the improved decode-and-forward (IDF) relay to maximize the system energy efficiency. Simulation results illustrate that，compared with the spectral-efficient maximization (SEM) algorithm, the energy-efficient maximization (EEM) algorithm proposed in this paper makes the energy efficiency not decline when the signal-to-noise radio (SNR) is at a high level. At the point where SNR is 10 dB and the number of subcarriers is 16, system energy efficiency is increased by 6.2% and 11.9% with the subcarrier pairing strategy and power allocation strategy respectively.
Ya-Hui Hu Liu Yinlong Zhou Xu Xu Zhen
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60682-3
One of the critical techniques of quality of experience (QoE) provisioning in single carrier frequency division multiple access (SC-FDMA) systems is related to implementation of efficient radio resource allocation (RRA) schemes. So far as we know, QoE-based RRA in SC-FDMA systems is still an open issue. Therefore, in this paper, five different QoE-based RRA schemes in SC-FDMA system are investigated based on different criteria. The first three QoE criteria applied in other wireless systems are maximizing average mean opinion score (MOS) over all users (Max-MOS), maximizing the minimum MOS among all users (MaxMin-MOS) and maximizing the minimum MOS with dropping some users requiring the highest amount of resources (MaxMin-MinMOSX.Y-MOS). Then, the improved MaxMin-MinMOSX.Y-MOS criterion focuses on changing user dropping principle to promote the probability of more users obtaining satisfied experience. By defining MOS higher than threshold as the effective MOS, maximizing average effective MOS over all users (Max-EMOS) is proposed as a totally new criterion which gives quantitative measurement of how many users to what extent obtaining satisfied experience. Mathematical expressions and solutions of these schemes are also presented in this paper. In addition, performance comparisons are made in simulations to further display their respective advantages and disadvantages.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60683-5
Cell outage compensation (COC) is a self-healing function of the self-organizing networks (SONs) concept for mobile wireless networks. In order to compensate the outage cell autonomously, this paper drives a solution for COC. This method is based on coordinated multiple points (CoMP) transmission and tilt adjusting. Firstly, the paper takes the coordinated pattern and tilt as the optimization objects. Then, it defines the rational objectives and the evaluation function of the situation and analysis the optimization model. Finally, based on the effective genetic algorithm (GA), the compensation mechanism is proposed. Simulation results show that this solution is better than the elder solutions in terms of coverage, interference, and throughput.
Yin-di YAO Zhibin ZENG
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60684-7
An effective method to broaden the rejection bandwidth of dump-shaped defected ground structure (DGS) filter design is proposed in the paper. One traditional dumbbell-shaped DGS is split by using one split ring, and reconstructed into two different compact DGSs. The distance between both of the DGSs is so close that there exists mutual inductance, which can be utilized to broaden the rejection bandwidth effectively. The effect of different parameters of the split ring on the rejection bandwidth and depth of the filter is analyzed. Simulated results demonstrate that, with the same area of 5.5mm by 10 mm, rejection bandwidth of the proposed filter is from 4.4 GHz to 10.5 GHz for the common-mode noise (CM) while that of the traditional dumbbell-shaped DGS is from 5.3 GHz to 7.3 GHz. Compared to other schematics adopting multiple DGS to broaden bandwidth, it can broaden the bandwidth by dividing the existed DGS into multiple parts and reconstructing a new filter. The experimental results show good agreement with simulated results.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60685-9
It has been known that DC arc faults pose a hazard in power electronics systems. Due to the fault current is lower than normal current load, series arc is more difficult to be discovered than parallel arc. The traditional methods of DC series arc faults detection have some disadvantages, such as large computation, long delay and easier influence by interferences. In this paper, a novel method with multi-scale morphological filtering was utilized for the fault detection of DC series arc. Compared to the tradition method, the proposed method is more simple and efficient. It was verified that it was convenient for field application of on-line monitoring and diagnosis with a good ability to prevent misjudgments from the environment interference.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (5). doi： 10.1016/S1005-8885(15)60686-0
This paper targets on energy saving and considers network responding time for backbone networks. The objective is to find idle links as many as possible which can be put into sleep mode under the situation of quality of service (QoS)-guaranteed. This paper proposes a software defined network (SDN) based routing strategy which is especially aimed at QoS-guaranteed energy saving for backbone networks. Under SDN structure, the topology change of network can be detected directly by network controller. And network can be managed more easily and effectively. Based on the open shortest path first (OSPF) protocol, network topology can be changed as little as possible in our strategy. So, the network reconfiguring time caused by the energy saving strategy will be decreased dramatically. This makes the strategy more feasible. Then the backbone network energy optimizing problem is transformed to the maximum clique problem (MCP). And, this paper designed a routing strategy called backbone networks energy saving strategy (BNESS) for energy saving in backbone networks. Simulation result shows that our proposed strategy can save energy and QoS can be guaranteed.