检索结果-南通市图书馆

SQUARE attack on block ciphers with low algebraic degree

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2010年第10期53卷 1988-1995页

作者： SUN Bing 1 , LI RuiLin 1 , QU LongJiang 1,3 & LI Chao 1,2,3 1 Science College of national university of Defense Technology, Changsha 410073, china 2 State Key laboratory of Information Security, Graduate university of Chinese Academy of Sciences, Beijing 100049, china 3 national mobile communications research laboratory, southeast university, nanjing 210096, china 1. Science College of national university of Defense Technology Changsha 410073 China3. National Mobile Communications Research Laboratory Southeast University Nanjing 210096 China2. State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China

By using an algebraic method, the mathematical foundation of SQUARE attack is studied in this paper. We point out that a SQUARE distinguisher exists if and only if the degree of the polynomial function between n-bit input which is active and n-bit output which is balanced is 2 n-2. And the algebraic method can also be used to determine the property of a balanced set after passed through a nonlinear S-box, by which in some cases we can find a SQUARE distinguisher with more rounds. The validity of SQUARE attack and the influence of the choice of S-box are also studied. If the round function of a Feistel cipher has a low algebraic degree, a SQUARE attack cannot recover the right keys in some special cases. However, SQUARE attack on SPN ciphers always holds. The relations among SQUARE attack and some other cryptanalytic method are studied, showing that if a cipher is breakable by SQUARE attack, then it is also breakable by the interpolation attack.

关键词： SQUARE attack interpolation attack integral attack block cipher

Low-complexity distributed differential spacetime coding scheme for amplify-and-forward cooperative networks

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science in china(Series F) 2009年第8期52卷 1418-1427页

作者： YU XiangBin1,2, BI GuangGuo3 & XU WeiYe4 1 College of Information Science and Technology, nanjing university of Aeronautics and Astronautics, nanjing 210016, china 2 Department of Electronic Engineering, City university of Hong Kong, Hong Kong, china 3 national mobile communications research laboratory, southeast university, nanjing 210096, china 4 Department of Communication Engineering, nanjing Institute of Technology, nanjing 211167, china College of Information Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Department of Electronic Engineering City University of Hong Kong Hong Kong China national mobile communications research laboratory Southeast University Nanjing 210096 China Department of Communication Engineering Nanjing Institute of Technology Nanjing 211167 China

By introducing a space-time coding scheme based on amicable orthogonality, we develop a distributed differential space-time coding scheme with the amplify-and-forward （AF） method for wireless cooperative networks. The scheme requires no knowledge of the channel state information at both transmitters and receivers, and effectively decreases the realization complexity due to no channel estimation. Moreover, it has lower decoding complexity and higher coding advantage than the existing scheme, thus avoiding the shortcoming of exponential decoding complexity of some existing schemes. According to the pairwise error probability （PEP） analysis of the system, the power allocations of source and relay terminals are jointly optimized, and as a result, the PEP is minimized, which will provide a helpful guideline for system design. Numerical calculation and simulation results show that the developed scheme is superior to the existing scheme. Moreover, the scheme with optimal power allocation yields obvious performance improvement over that with equal power allocation.

关键词： differential space-time coding cooperative communication amplify-and-forward method power allocation

Decoding algorithms for shortened-extended turbo product codes in WiMAX systems

在线全文

学校读者我要写书评

暂无评论

Science in china(Series F) 2009年第12期52卷 2415-2423页

作者： XU ChangLong1,3,4, YANG Wei1,2 & YE WeiChen4 1 State Key laboratory of Networking and Switching Technology, Beijing university of Posts and Telecommunications, Beijing 100044, china 2 State Key laboratory of Rail Traffic Control and Safety, Beijing Jiaotong university, Beijing 100044, china 3 national mobile communications research laboratory, southeast university, nanjing 210096, china 4 Intel Corporation, Beijing Kerry Center, Guanghua Road 1, Beijing 100020, china State Key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100044 China State Key laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing 100044 China national mobile communications research laboratory Southeast University Nanjing 210096 China Intel Corporation Beijing Kerry Center Guanghua Road 1 Beijing 100020 China

The component codes of turbo product codes in WiMAX systems are extended Hamming codes and single parity check codes as well as their shortened forms, In this paper, three novel iterative decoding algorithms based on Chase, MAP algorithms and their combination are proposed for shortened-extended turbo product codes. The iterative decoding algorithm based on Chase algorithm is proposed to reduce the decoding complexity without any performance loss. An efficient MAP algorithm is then proposed to decode the component codes of shortened single parity check codes and shortened-extended Hamming codes. A comprehensive performance comparison of the proposed decoding schemes is conducted for three typical classes of turbo product codes in WiMAX OFDMA systems. The suitable decoding algorithms are recommended for different classes based on the simulation results.

关键词： block code product code iterative decoding

A survey of next generation mobile communications researchin china

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2011年第5期56卷 2875-2888页

作者： TIAN JinFeng 1,2 , ZHENG XiaoYing 2,3 , HU HongLin 1,2 YOU XiaoHu 1,3 1 Shanghai research Center for Wireless communications (WiCO), Shanghai 200335, china 2 Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050, china 3 national mobile communications research laboratory, southeast university (SEU), nanjing 210096, china Shanghai research Center for Wireless communications (WiCO) Shanghai Institute of Microsystem and Information Technology (SIMIT) Chinese Academy of Sciences (CAS) national mobile communications research laboratory Southeast University (SEU)

With the rapid development of wireless communication networks, the fourth generation (4G) has emerged to move beyond the limitations of the third generation (3G), with increased bandwidth, enhanced quality of services, and reduced costs of resources. In this paper, we discuss the key technologies of 4G and focus on surveying the ongoing research in 4G communications in china. The 4G technologies under investigation include multicarrier transmission, multiple antenna techniques, carrier aggregation, relays, cognitive radio, distributed antenna systems, network convergence, and network self-optimization. These technologies are the building blocks of 4G and contribute largely to the requirements of International mobile Telecommunications Advanced (IMT-Advanced). For each technology, its benefits, research topics, and some existing approaches are examined. Finally, we briefly discuss the challenges and future research issues in 4G systems.

关键词：下一代移动通信中国无线通信网络分布式天线系统 4G系统多载波传输国际移动通信认知无线电

同方期刊数据库

在线全文

学校读者我要写书评

暂无评论

无线个域网应用环境下速率自适应算法的研究

通信学报 2004年第4期25卷 160-167页

作者：叶芝慧沈连丰沈克勤陈锦泰东南大学移动通信国家重点实验室江苏南京210096 解放军理工大学指挥自动化学院江苏南京210007 香港中文大学电子工程学系

首先对无线个域网(WPAN)应用环境下的干扰模型进行了分析,在此基础上提出了在WPAN工作的系统中引入速率自适应控制算法以提高诸系统的抗干扰性能,并减小对系统内其它设备及不同系统间设备的相互干扰.文章对自适应速率控制算法进行了分析... 详细信息

首先对无线个域网(WPAN)应用环境下的干扰模型进行了分析,在此基础上提出了在WPAN工作的系统中引入速率自适应控制算法以提高诸系统的抗干扰性能,并减小对系统内其它设备及不同系统间设备的相互干扰.文章对自适应速率控制算法进行了分析,然后以蓝牙系统为例,给出了自适应速率控制算法对蓝牙系统性能改善的程度,重点讨论了对系统误比特率的影响.仿真结果显示,在理想反馈信道条件下,随着单信道信噪比的改善,自适应速率控制系统的最佳误比特率比固定速率传输系统有1～3个数量级的改善;即使采用简单的双速率自适应控制系统,也可以得到1～2个数量级的改善.由此得到的结果同样可应用于其它工作于无线个域网的系统.

关键词：无线个域网自适应速率控制固定速率系统蓝牙系统 IEEE 802.11b

Blind estimation of multipath delays in OFDM systems

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第6期55卷 1397-1401页

作者： SHENG Bin & YOU XiaoHu national mobile communications research laboratory,southeast university,nanjing 210096,china 1. national mobile communications research laboratory Southeast University Nanjing 210096 China

In order to coherently detect the transmitted data symbols,an orthogonal frequency division multi-plexing (OFDM) receiver requires reliable identification and equalization of the experienced wireless multipath fading *** information of path delays plays an important role in the procedure of identification and *** need for high data rates motivated the search for blind identification and equalization methods because they save bandwidth by avoiding the use of training *** OFDM systems,multipath fading channels introduce interference between adjacent symbols which can be prevented by inserting a cyclic prefix (CP) before each *** this paper,we find that the power of the interference in the CP interval can be estimated by using the circular convolution and based on the variations of the interference power,the time delay of each path can be estimated blindly.

关键词： multipath delay cyclic prefix OFDM

Multi-user MIMO downlink eigen-mode transmission over jointly correlated MIMO channels

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2011年第10期54卷 2124-2137页

作者： LI Xiao ,JIN Shi & GAO XiQi national mobile communications research laboratory,southeast university,nanjing 210096,china 1. national mobile communications research laboratory Southeast University Nanjing 210096 China

The study of multi-user multiple-input multiple-output (MU-MIMO) systems has emerged recently as an important research topic because such systems have the potential to combine the high capacity that can be achieved through MIMO processing with the benefits of spatial-division ***,receiver and transmitter channel state information (CSI) is generally required,especially for the downlink *** this paper,MU-MIMO downlink transmission systems with statistical CSI at the transmitter are studied for jointly correlated MIMO ***-mode space division multiple access transmission is derived based on the maximization of the ergodic sum rate,and two eigen-mode power allocation algorithms are proposed using matrix permanent and convex optimization *** new algorithms can overcome the limitations of the existing multi-user downlink transmission algorithm in practical applications.

关键词： MIMO eigen-mode multi-user downlink

Spectral Estimation based on Filter Bank and Cepstrum Thresholding for Cognitive Radios

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

china communications 2009年第1期6卷 92-98页

作者： Cao Zhiping, Bi Guangguo, Zhang Zaichen national mobile Communication research laboratory, School of Information Science and Engineering, southeast university, nanjing 210096, china national mobile Communication research laboratory School of Information Science and Engineering Southeast University Nanjing 210096 China

Spectrum sensing plays an important role in cognitive radio (CR). Nonparametric spectrum estimation is considered as a feasible candidate for CR. Some filter bank based periodogram algorithms, such as Thomson’s multitaper spectral estimator, can achieve fine spectral dynamic range1 but have large estimation variance. On the other hand, recently, Cepstrum Thresholding is proposed to reduce the variance of periodogram estimation. In this paper, we combine these two methods to achieve spectral dynamic range and variance request at the same time.

关键词： spectrum analysisfifilter bank cepstrum thresholding.

Performance analysis of variable-power adaptive modulation in space-time block coded MIMO diversity systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2010年第10期53卷 2106-2115页

作者： YU XiangBin 1,2 & SHI HuiBin 1 1 College of Information Science and Technology, nanjing university of Aeronautics and Astronautics, nanjing 210016, china 2 national mobile communications research laboratory, southeast university, nanjing 210096, china 1. College of Information Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. National Mobile Communications Research Laboratory Southeast University Nanjing 210096 China

In this paper, the performance analysis of multi-antenna MIMO systems with variable-power (VP) adaptive modulation and space-time coding is presented. The fading gain value is partitioned into a number of regions by which we decide the transmission power according to the region the fading gain falls in. The optimum fading gain region boundaries (switching thresholds) for maximizing spectrum efficiency (SE) under a target BER and average power constraint are derived. It is shown that the Lagrange multiplier in the constrained SE optimization will be unique if the existence condition for multi-antenna systems is satisfied, and is unique for single antenna systems. A practical iterative calculation method based on Steepest Descent Algorithm for finding the Lagrange multiplier is proposed. With the switching thresholds, the closed-form expressions of the SE and average BER, respectively for VP system and constant-power (CP) system are achieved. Simulation results for SE and average BER are in good agreement with the theory analysis. The results show that VP adaptive modulation with space-time coding provides better SE than the counterpart with CP under a target BER and average power constraint.

关键词： adaptive modulation variable power space-time block code constant power multiple input multiple output (MIMO)