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30 December 2011, Volume 16 Issue 6 Previous Issue    Next Issue
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Reputation-Based Collaborative Spectrum Sensing Scheme in Cognitive Radio Networks ZHAO Shi-kang (赵士康), HE Di (何 迪), LI Wen-hua (李文化), ZHU Fu-sheng (朱伏生) 2011, 16 (6):  641-647.  doi: 10.1007/s12204-011-1204-6 Abstract ( 2483 )    Collaborative spectrum sensing is proposed to improve the detection performance in cognitive radio (CR) networks. However, most of the current collaborative sensing schemes are vulnerable to the interference of the malicious secondary users (SUs). In this paper we propose a reputation-based collaborative spectrum sensing scheme to improve the security of cooperative sensing by mitigating the impacts of misbehaviors. The fusion center calculates the reputation rating of each SU according to their history reports to weight their sensing results in the proposed scheme. We analyze and evaluate the performance of the proposed scheme and its advantages over previous schemes in expansibility and integrity. Simulation results show that the proposed scheme can minimize the harmful influence from malicious SUs. References | Related Articles | Metrics

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Optimization Design of Two-Stage Operational Amplifier with Frequency Compensation via Geometric Programming LI Dan (李 丹), RONG Meng-tian (戎蒙恬), SHU Guo-hua (殳国华) 2011, 16 (6):  648-651.  doi: 10.1007/s12204-011-1205-5 Abstract ( 1528 )    An optimization design technique to obtain global solution for a two-stage operational amplifier (op-amp) with frequency compensation is presented. This frequency compensation technique can adjust the equivalent resistance to guarantee that the phase margin is stable even though circumstance temperature varies. Geometric programming is used to optimize the component values and transistor dimensions.  It is used in this analog integrated circuit design to calculate these parameters automatically.  This globally optimal amplifier obtains minimum power while other specifications are fulfilled. References | Related Articles | Metrics

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A Selection Scheme for Optimum Number of   Cooperative Secondary Users in Spectrum Sensing LIN Ying-pei (林英沛), HE Chen (何 晨), JIANG Ling-ge (蒋铃鸽), HE Di (何 迪) 2011, 16 (6):  652-657.  doi: 10.1007/s12204-011-1206-4 Abstract ( 1540 )    An optimization scheme for choosing the optimum number of secondary users in cooperative spectrum sensing based on the cyclostationary feature detection with Neyman-Pearson criterion is proposed in this paper. The optimal soft combination test statistic for the cooperative spectrum sensing based on cyclostationary feature detection is derived according to the generalized likelihood ratio test and its corresponding detection performance is deduced. A target function, considering two important parameters as the resource use efficiency and the number of samples employed by each cooperative secondary user in the system design, is constructed to obtain the optimum number of cooperative secondary users. It can be found that the selection scheme is to make a tradeoff between the system complexity of the cognitive radio network and the global sensing performance of the cooperative spectrum sensing. References | Related Articles | Metrics

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An Efficient Threshold Key-Insulated Signature Scheme CHEN Jian-hong (陈剑洪), LONG Yu (龙 宇), CHEN Ke-fei (陈克非) WANG Yong-tao (王永涛),LI Xiang-xue (李祥学) 2011, 16 (6):  658-662.  doi: 10.1007/s12204-011-1207-3 Abstract ( 1387 )   To tackle the key-exposure problem in signature settings, this paper introduces a new cryptographic primitive named threshold key-insulated signature (TKIS) and proposes a concrete TKIS scheme．For a TKIS system, at least k out of n helpers are needed to update a user's temporary private key. On the one hand, even if up to k-1 helpers are compromised in addition to the exposure of any of temporary private keys, security of the non-exposed periods is still assured. On the other hand, even if all the n helpers are compromised, we can still ensure the security of all periods as long as none of temporary private keys is exposed. Compared with traditional key-insulated signature (KIS) schemes, the proposed TKIS scheme not only greatly enhances the security of the system, but also provides flexibility and efficiency. References | Related Articles | Metrics

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Directed Proxy Signature in the Standard Model MING Yang (明 洋), WANG Yu-min (王育民) 2011, 16 (6):  663-671.  doi: 10.1007/s12204-011-1208-2 Abstract ( 1749 )    restricted verification ability.  Directed signatures allow only a designated verifier to check the validity of the signature issued to him, and at the time of trouble or if necessary, any third party can verify the signature with the help of the signer or the designated verifier. Directed signature schemes are widely used in situations where the receiver's privacy should be protected. Proxy signatures allow an entity to delegate its signing capability to another entity in such a way that the latter can sign message on behalf of the former when the former is not available. Proxy signature schemes have found numerous practical applications such as distributed systems and mobile agent applications. In this paper, we firstly define the notion of the directed proxy signature by combining the proxy signature and directed signature. Then, we formalize its security model and present a concrete scheme in the standard model. Finally, we use the techniques from provable security to show that the proposed scheme is unforgeable under the gap Diffie-Hellman assumption, and invisible under the decisional Diffie-Hellman assumption. References | Related Articles | Metrics

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Chosen Ciphertext Secure Identity-Based Broadcast Encryption in the Standard Model SUN Jin (孙 瑾), HU Yu-pu (胡予濮), ZHANG Le-you (张乐友) 2011, 16 (6):  672-676.  doi: 10.1007/s12204-011-1209-1 Abstract ( 1565 )    To give concurrent consideration both the efficiency and the security (intensity of intractable problem) in the standard model, a chosen ciphertext secure identity-based broadcast encryption is proposed. Against the chosen ciphertext security model, by using identity (ID) sequence and adding additional information in ciphertext, the self-adaptive chosen identity security (the full security) and the chosen ciphertext security are gained simultaneously. The reduction of scheme's security is the decisional bilinear Diffie-Hellman (BDH) intractable assumption, and the proof of security shows that the proposed scheme is indistinguishable against adaptive chosen ciphertext attacks in the standard model under the decisional BDH intractable assumption. So the security level is improved，and it is suitable for higher security environment. References | Related Articles | Metrics

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Pre-emptive Channel Borrowing and Traffic Overflowing Channel Allocation Scheme for Multimedia Overlay Networks ZHAO Fang-ming (赵方明), HANG Juan (杭 娟), HE Di (何 迪) 2011, 16 (6):  677-686.  doi: 10.1007/s12204-011-1210-8 Abstract ( 1207 )    This paper proposes a channel allocation scheme for multimedia wireless networks, in which a two-layer macro-cell or micro-cell architecture is considered. Macro-cells are used to access high-mobility services; while micro-cells, which are overlaid by the macro-cells, are used to cater low-mobility services. To analyze the scheme, a multidimensional Markov traffic model is firstly developed, in which traffic characteristic of two special periods of time is considered. And then, a pre-emptive channel-borrowing scheme combined with traffic-overflowing strategy for multimedia (voice, video or data) networks is proposed, in which handoff requests can not only borrow channels from adjacent homogenous cells, but also be overflowed to heterogeneous cells. Priority strategies are also dedicated to high-mobility services for they can pre-empt channels being used by low-mobility services in macro-cells. To meet the high quality of service (QoS) requirements of video services and increase the channel utilization ratio, video services can be transformed between real-time services and non-real-time services as necessary. Simulation results show that our schemes can decrease the blocking probabilities and improve the channel utilization. References | Related Articles | Metrics

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Model and Simulation of a New Ultra-Narrow Trigger Frequency Alterable Pulse Generator YANG Yun-feng (杨运峰), CAO Zhen-xin (曹振新), YE Zhan(叶 展), DOU Wen-bin (窦文斌), SU Hong-yan (苏宏艳) 2011, 16 (6):  687-690.  doi: 10.1007/s12204-011-1211-7 Abstract ( 1751 )    Two new kinds of ultra-narrow trigger frequency alterable picosecond pulse generator are presented. One can produce positive pulses and the other can produce negative pulses. The two pulse generators are subdivided into three parts: signal driving circuit, differentiator network and pulse shaping circuit. The pulse shaping circuit is made of step recovery diode (SRD) and short-circuit microstrip line. A positive pulse with width of 54 ps (50% ---50% ), rising time of 30 ps (10%  ---90%  ) and falling time of 32 ps (90%  ---10%  ), and a negative pulse with width of 54 ps (50%  ---50%  ), rising time of 30 ps (90%  ---10%  ) and falling time of 30 ps (10%  ---90%  ) are achieved in simulation. All of the components are ready-made and inexpensive. They can be applied in ultra-wideband (UWB) communication system, such as transmitters and receivers. References | Related Articles | Metrics

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Joint User and Antenna Selection for  Multiuser MIMO Downlink with Block Diagonalization LIU Wei (刘 伟), ZOU Jun (邹 俊), LUO Han-wen (罗汉文), MA Ji-peng (马继鹏) 2011, 16 (6):  691-695.  doi: 10.1007/s12204-011-1212-6 Abstract ( 1519 )     User selection is necessary for multiuser multiple-input multiple-output (MIMO) downlink systems with block diagonalization (BD) due to the limited free spatial transmit dimensions. The pure user selection algorithms can be improved by performing receive antenna selection (RAS) to increase sum rate. In this paper, a joint user and antenna selection algorithm, which performs user selection for sum rate maximization in the first stage and then performs antenna selection in the second stage, is proposed. The antenna selection process alternately drops one antenna with the poorest channel quality based on maximum determinant ranking (MDR) from the users selected during the first stage and activates one antenna with the maximum norm of projected channel from the remaining users. Simulation results show that the proposed algorithm significantly outperforms the algorithm only performing user selection as well as the algorithm combining user selection with MDR receive antenna selection in terms of sum rate. References | Related Articles | Metrics

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Optimal Linear Phase Finite Impulse Response Band Pass   Filter Design Using Craziness Based Particle Swarm   Optimization Algorithm SANGEETA Mandal, SAKTI Prasad Ghoshal, RAJIB Kar, 2011, 16 (6):  696-703.  doi: 10.1007/s12204-011-1213-5 Abstract ( 2210 )    An efficient method is proposed for the design of finite impulse response (FIR) filter with arbitrary pass band edge, stop band edge frequencies and transition width. The proposed FIR band stop filter is designed using craziness based particle swarm optimization (CRPSO) approach. Given the filter specifications to be realized, the CRPSO algorithm generates a set of optimal filter coefficients and tries to meet the ideal frequency response characteristics. In this paper, for the given problem, the realizations of the optimal FIR band pass filters of different orders have been performed. The simulation results have been compared with those obtained by the well accepted evolutionary algorithms, such as Parks and McClellan algorithm (PMA), genetic algorithm (GA) and classical particle swarm optimization (PSO). Several numerical design examples justify that the proposed optimal filter design approach using CRPSO outperforms PMA and PSO, not only in the accuracy of the designed filter but also in the convergence speed and solution quality. References | Related Articles | Metrics

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Chaff Cloud Jamming Suppression Based on Wavelet Transform ZHAO Hai-bo (赵海波), PEI Jin-ze (裴晋泽), ZHAO Lei-ming (赵雷鸣), HU Guang-rui (胡光锐) 2011, 16 (6):  704-707.  doi: 10.1007/s12204-011-1214-4 Abstract ( 1360 )    Radar target signals and chaff cloud jamming signals have different characters by the wavelet transform. The wavelet coefficients of radar target signals are highly correlated with its near-and-near-scale wavelet coefficients, however the correlativity between the wavelet coefficients of chaff cloud jamming signals and its near-and-near scale wavelet coefficients is less significant. Based on the binary-base discrete wavelet transform and the correlation algorithm, the method of target entropy to estimate standard variance of the jamming signals and each scale is proposed to ensure reasonable threshold, to suppress chaff cloud signals and finally to reconstruct mixed signals by the improved spatially selective noise filtration (ISSNF) method. The extensive simulation results show that the proposed method can availably suppress chaff cloud jamming and decontaminate target echo. References | Related Articles | Metrics

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Efficient Clustering and Simulated Annealing Approach  for Circuit Partitioning SANDEEP Singh Gill, RAJEEVAN Chandel, ASHWANI Kumar Chandel 2011, 16 (6):  708-712.  doi: 10.1007/s12204-011-1138-z Abstract ( 1941 )   Circuit net list bipartitioning using simulated annealing technique has been proposed in the paper. The method converges asymptotically and probabilistically to global optimization. The circuit net list is partitioned into two partitions such that the number of interconnections between the partitions is minimized. The proposed method begins with an innovative clustering technique to obtain a good initial solution. Results obtained show the versatility of the proposed method in solving non polynomial hard problems of circuit net list partitioning and show an improvement over those available in literature. References | Related Articles | Metrics

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Improved Preimage Attack on 3-Pass HAVAL ZHONG Jin-min (钟锦敏), LAI Xue-jia (来学嘉), DUAN Ming (段 明) 2011, 16 (6):  713-721.  doi: 10.1007/s12204-011-1215-3 Abstract ( 1750 )    HAVAL is a hash function proposed by  Zheng et al. in 1992, including 3-, 4- and 5-pass versions. We improve pseudo-preimage and preimage attacks on 3-pass HAVAL at the complexity of 2^  172   and 2^  209.6  , respectively, as compared to the previous best known results: 2^  192   and 2^  225  by Sasaki et al. in 2008. We extend the skip interval for partial-patching and apply the initial structure technique to find the better message chunks, and combine the indirect-partial-matching, partial-fixing and multi-neutral-word partial-fixing techniques to improve the attacks based on the meet-in-the-middle method. These are the best pseudo-preimage and preimage attacks on 3-pass HAVAL. References | Related Articles | Metrics

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Fusion of Remote Sensing Images Based on   Nonsubsampled Contourlet Transform and Region Segmentation WU Yi-quan (吴一全), WU Chao (吴 超), WU Shi-hua (吴诗婳) 2011, 16 (6):  722-727.  doi: 10.1007/s12204-011-1216-2 Abstract ( 1799 )   The purpose of remote sensing images fusion is to produce a fused image that contains more clear, accurate and comprehensive information than any single image. A novel fusion method is proposed in this paper based on nonsubsampled contourlet transform (NSCT) and region segmentation. Firstly, the multispectral image is transformed to intensity-hue-saturation (IHS) system. Secondly, the panchromatic image and the component intensity of the multispectral image are decomposed by NSCT. Then the NSCT coefficients of high and low frequency subbands are fused by different rules, respectively. For the high frequency subbands, the fusion rules are also unalike in the smooth and edge regions. The two regions are segregated in the panchromatic image, and the segmentation is based on particle swarm optimization. Finally, the fusion image can be obtained by performing inverse NSCT and inverse IHS transform. The experimental results are evaluated by both subjective and objective criteria. It is shown that the proposed method can obtain superior results to others.   References | Related Articles | Metrics

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Micro-Electro-Mechanical-Sensor Inertial Navigation    System-Assisted Global Navigation Satellite System     Receiver  Acquisition Scheme and Performance Evaluation YE Ping (叶 萍), ZHAN Xing-qun (战兴群), ZHANG Yan-hua (张炎华) 2011, 16 (6):  728-733.  doi: 10.1007/s12204-011-1217-1 Abstract ( 1543 )   When an aircraft moves under a low carrier-to-noise ratio (CNR) or at a high speed, increasing the sensitivity of global navigation satellite system (GNSS) receiver is a goal quite hard to achieve. A novel acquisition scheme assisted with micro-electro-mechanical-sensor (MEMS) inertial navigation system (INS) is presented to estimate the Doppler caused by user dynamics relative to each satellite ahead of time. Based on tightly coupled GNSS/INS estimation algorithm, MEMS INS Doppler error that can be achieved is first described. Then, by analyzing the mean acquisition time and signal detection probability, the MEMS INS-assisted acquisition capabilities in cold, warm and hot starts are quantitatively determined and compared with the standard GNSS acquisition capability. The simulations and comparisons have shown that: the acquisition time in cold start can be shortened by at least 23 s, the time in warm start can be shortened to 1 s and the acquisition capability is improved 95%, and the reacquisition time in hot start can be shortened by around 0.090 s and the capability can be enhanced 40%. The results demonstrate the validity of the novel method. References | Related Articles | Metrics

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Solving the Euclidean Steiner Minimum Tree Using    Cellular Stochastic Diffusion Search Algorithm ZHANG Jin (张 瑾), ZHAO Ya-liang (赵雅靓), MA Liang (马 良) 2011, 16 (6):  734-741.  doi: 10.1007/s12204-011-1218-0 Abstract ( 1556 )    The Euclidean Steiner minimum tree problem is a classical NP-hard combinatorial optimization problem. Because of the intrinsic characteristic of the hard computability, this problem cannot be solved accurately by efficient algorithms up to now. Due to the extensive applications in real world, it is quite important to find some heuristics for it. The stochastic diffusion search algorithm is a newly population-based algorithm whose operating mechanism is quite different from ordinary intelligent algorithms, so this algorithm has its own advantage in solving some optimization problems. This paper has carefully studied the stochastic diffusion search algorithm and designed a cellular automata stochastic diffusion search algorithm for the Euclidean Steiner minimum tree problem which has low time complexity. Practical results show that the proposed algorithm can find approving results in short time even for the large scale size, while exact algorithms need to cost several hours. References | Related Articles | Metrics

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Aero-Optical Characteristics of Supersonic Flow over   Blunt Wedge with Cavity Window LI Bo (李 波), LIU Hong (刘 洪) 2011, 16 (6):  742-749.  doi: 10.1007/s12204-011-1219-z Abstract ( 1630 )   The optical rays that form the image of an object and propagate a supersonic flow over a vehicle are refracted by the density variations. A numerical analysis of the aero-optical characteristics of supersonic flow over blunt wedge with a cavity window is carried out. A hybrid method of Reynold averaged Navier-Stokes and direct simulation Monte Carlo (RANS/DSMC) is employed to simulate the flowfield. Refraction factor is introduced to evaluate the flowfield's aero-optical characteristic. The results show that mean flow's aero-optical effects are mainly caused by the shock wave, the expansion wave and the turbulent boundary layer. Fluctuation flow's aero-optical effects are mainly caused by the turbulent boundary layer and the shock wave induced by the cavity window. The aero-optical effects at the leading side of window are caused by the mean density variations, while the effects at the trailing side are caused by the density fluctuations. Different draft angles of the cavity window are investigated. The airborne optical devices of supersonic vehicle should be mounted in the middle of the cavity window with a large draft angle. References | Related Articles | Metrics

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Structure-Borne Sound Attenuation at Corner Interface with Dynamic Vibration Absorber Attached CHE Chi-dong (车驰东), CHEN Duan-shi (陈端石) 2011, 16 (6):  750-758.  doi: 10.1007/s12204-011-1220-6 Abstract ( 1578 )   Structure-borne sound attenuation at corner interface of two plates with dynamic vibration absorber attached is investigated by wave approach. Equations governing transmission and reflection coefficients are deduced by introducing some non-dimensional coefficients, which help to reveal the physical sense inside and to simplify the analysis. Numerical investigation on vibration energy transmission of bending wave is carried out as well. The results from measurement and prediction show almost the same trends in the simplified experiment. It is found that energy transmission at corner interface depends greatly on whether the dynamic vibration absorber attached acts at resonance and is relatively lower right after the nature frequency of dynamic vibration absorber. Furthermore, the dynamic vibration absorber attached provides less energy transmission of bending wave than blocking mass at the end of ``passing band''.   References | Related Articles | Metrics

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Sensitivity Analysis of Thermal Properties on   Numerical Simulation Results of Quenching Process ZHOU Zhi-fang (周志方), GU Jian-feng (顾剑锋), WANG Xiao-yan (王晓燕), PAN Jian-sheng (潘健生) 2011, 16 (6):  759-762.  doi: 10.1007/s12204-011-1221-5 Abstract ( 1446 )   A three-factor three-level orthogonal test project has been designed based on the numerical simulation of a Jominy quenching process. Then the data scattering effects of thermal conductivity and enthalpy of tested steel, as well as the heat exchange coefficients of the cooling media, on the results have been studied. The results can be used as a reference for choosing the input thermal parameter in finite element simulation of quenching, and for evaluating the simulation results.   References | Related Articles | Metrics