1、中文3100字，2100英文单词，12500英文字符附录 7： 北京联合大学毕业设计（论文）外文原文及译文 题目 ： 基于 FPGA 数字示波器设计 &n
2、bsp; 专业： 通信工程 指导教师： 韩玺 学院： 信息
3、 学号： 2010080304129 班级： 1008030401 姓名：
4、张建明 一、外文原文 Design and FPGA implementation of a wireless hyperchaotic communication system for secure real-time image transmission Abstract In this paper, we propose and demonstrate experimentally
5、a new wireless digital encryption hyperchaotic communication system based on radio frequency (RF) communication protocols for secure real-time data or image transmission. A reconfigurable hardware architecture is developed to ensure the interconnection between two field programmable gate array devel
6、opment platforms through XBee RF modules. To ensure the synchronization and encryption of data between the transmitter and the receiver, a feedback masking hyperchaotic synchronization technique based on a dynamic feedback modulation has been implemented to digitally synchronize the encrypter hyperc
7、haotic systems. The obtained experimental results show the relevance of the idea of combining XBee (Zigbee or Wireless Fidelity) protocol, known for its high noise immunity, to secure hyperchaotic communications. In fact, we have recovered the information data or image correctly after real-time encr
8、ypted data or image transmission tests at a maximum distance (indoor range) of more than 30 m and with maximum digital modulation rate of 625,000 baud allowing a wireless encrypted video transmission rate of 25 images per second with a spatial resolution of 128 128 pixels. The obtained performance o
9、f the communication system is suitable for secure data or image transmissions in wireless sensor networks. Introduction Over the past decades, the confidentiality of multimedia communications such as audio, images, and video has become increasingly important since communications of digital pr
10、oducts over the network (wired/wireless) occur more frequently. Therefore, the need for secure data and transmission is increasing dramatically and defined by the required levels of security depending on the purpose of communication. To meet these requirements, a wide variety of cryptographic algori
11、thms have been proposed. In this context, the main challenge of stream cipher cryptography relates to the generation of long unpredictable key sequences. More precisely, the sequence has to be random, its period must be large, and the various patterns of a given length must be uniformly distributed
12、over the sequence. Traditional ciphers like DES, 3DES, IDEA, RSA, or AES are less efficient for real-time secure multimedia data encryption systems and exhibit some drawbacks and weakness in the high streamdata encryption. Indeed, the increase and availability of a high-power computation machine all
13、ow a force brute attack against these ciphers. Moreover, for some applications which require a high-level computation and where a large computational time and high computing power are needed (for example, encryption of large digital images), these cryptosystems suffer from low-level efficiency. Cons
14、equently, these encryption schemes are not suitable for many high-speed applications due to their slow speed in real-time processing and some other issues such as in the handling of various data formatting. Over the recent years, considerable researches have been taken to develop new chaotic or hype
15、rchaotic systems and for their promising applications in real-time encryption and communication. In fact, it has been shown that chaotic systems are good candidates for designing cryptosystems with desired properties. The most prominent is sensitivity dependence on initial conditions and system para
16、meters, and unpredictable trajectories. Furthermore, chaos-based and other dynamical systembased algorithms have many important properties such as the pseudorandom properties, ergodicity and nonperiodicity. These properties meet some requirements such as sensitivity to keys, diffusion, and mi
17、xing in the cryptographic context. Therefore, chaotic dynamics is expected to provide a fast and easy way for building superior performance cryptosystems, and the properties of chaotic maps such as sensitivity to initial conditions and random-like behavior have attracted the attention to develop dat
18、a encryption algorithms suitable for secure multimedia communications. Until recently, chaotic communication has been a subject of major interest in the field of wireless communications. Many techniques based on chaos have been proposed such as additive chaos masking (ACM), where the analog message
19、signal is added to the output of the chaos generator within the transmitter. In, chaos shift keying is used where the binary message signal selects the carrier signal from two or more different chaotic attractors. Authors use chaotic modulation where the message information modulates a parameter of
20、the chaotic generator. Chaos control methods rely on the fact that small perturbations cause the symbolic dynamics of a chaotic system to track a prescribed symbol sequence. In, the receiver system is designed in an inverse manner to ensure the recovery of the encryption signal. An impulsive synchro
21、nization scheme is employed to synchronize chaotic transmitters and receivers. However, all of these techniques do not provide a real and practical solution to the challenging issue of chaotic communication which is based on extreme sensitivity of chaotic synchronization to both the additive channel
22、 noise and parameter mismatches. Precisely, since chaos is sensitive to small variations of its initial conditions and parameters, it is very difficult to synchronize two chaotic systems in a communication scheme. Some proposed synchronization techniques have improved the robustness to parameter mis
23、matches as reported in, where impulsive chaotic synchronization and an open-loop-closed-loopbased coupling scheme are proposed, respectively. Other authors proposed to improve the robustness of chaotic synchronization to channel noise, where a coupled lattice instead of coupled single maps is used to decrease the master-slave synchronization error. In, symbolic dynamics-based noise
