Advanced Materials Research Vols. 945-949

Abstract: This paper mainly introduces the basic principles of BCH code, which is a type of error control codes. The error control system is an important method to improve the communication transmission system. Communication system that containing BPSK modulation is built by MATLAB and through simulating and analyzing the performance of BCH communication systems, it was discovered that the BCH code transmission characteristic has significant gain. This paper provides the theory basis for the projects that contain BCH code.

Abstract: In this Letter, assuming a Nakagami-m fading scenario, closed-form asymptotic expressions for the average symbol error probability (ASEP) of dual-hop amplify-and-forward (AF) cooperative systems with partial relay selection are derived. Based on these expressions, the diversity order is obtained and insightful conclusions are drawn. Numerical results are plotted and the asymptotic curves match very well in the medium and high signal-to-noise ratio (SNR) regions with those obtained by simulations.

Abstract: In space laser communication tracking turntable work environment characteristics, we design a neural network PID control system which makes the system’s parameter self-tuning. The control system cans self-tune parameters under the changes of the object’ mathematic model, it solves the problem for the control object’s model changes under the space environment. It also looks for method for optimum control through the function of neural network's self-learning in order to solve the problem of the precision’s decline which arouse from vibration and disturbance. The simulation experiments confirmed the self-learning ability of neural network, and described the neural PID controller dynamic performance is superior to the classical PID controller through the output characteristic curves contrast.

Abstract: In the development process of modern radio communication device, it is important of merits that the frequency of the generator performance, which can directly affect the performance of the communication device. In usual, often used to motivate phase-locked loop (PLL) to realize the broadband frequency synthesizer of low noise and direct digital synthesizer (DDS) of small step. This paper expounded a kind of technology that realized S-band DDS-driven PLL low spurious frequence synthesizer.Designed to get which the bandwidth of 250MHz and spurious suppression indicators meet the whole band is better than -65dBc.

Abstract: It is known that practical quantum key distribution system, because of the imperfect of devices, has sort of loopholes, so Eve can attack through these loopholes. The proposition of measurement device independent quantum key distribution protocol claimed to solve all the loopholes at the detector side. However the proof of MDI-QKD is based on the Hong-Ou-Mandel effect at 50:50 beam splitter. And with current experimental technology, a realistic beam splitter, made by fused biconical technology, has a wavelength-dependent property. Based on this fatal security loophole, the author propose a wavelength-dependent attacking protocol, which can be applied to practical MDI-QKD systems. Through this attacking protocol the author theoretical estimated that the eavesdropper could get 70% of the encoding information with a QBER of only 0.04.

Abstract: The Infrared transfer using data transport protocol plus sign, plus software validation for data transmission, is usually transfer technology. This article provides an overview of the design of hardware circuit simulation of infrared transmission of SPI protocol, and details about the process of transmitting and the receiving program and how it works, and points out some problems which need paying more attention in the design process.

Abstract: DRP is considered as a business function for the continuity of business, which can be used to build a suitable IT infrastructure. Using DRP, a company's data is easily secured, maintained or resumed. Therefore, this article provides an overview of DRP and performs it for an organization with three branches.

Abstract: There is difficult to acquire channel state information in massive MU-MIMO system. A downlink pilots precoding scheme I s proposed for efficient channel estimation. With the scheme, the BS precodes the pilot sequences and forwards to all users. The channel estimation overhead of this scheme does not depend on the number of BS antennas, and is only proportional to the number of users. We then derive several precoding techniques which enables us to implement the proposed scheme. Finally in simulation the proposed algorithm is compared with conventional algorithms without precoding training in spectral efficiency. The simulation results show that the proposed scheme performs better than the existing schemes.

Abstract: Spectrum sensing performance of building indoor environment has been the focus of attention and research in low signal-to-noise ratio. In this paper, a primary users sensing approach to signal classification combining spectral correlation analysis and support vector machine (SVM) is introduced. Three spectral coherence characteristic parameters are chosen via spectral correlation analysis. By utilizing a nonlinear SVM, primary user signal has been detected. Simulations indicate that the overall success rate is above 90.2% when SNR is equal to-5dB and 80.1% in-15dB. Compared to the existing methods including the classifiers based on MME and ANN, the proposed approach is more effective in the case of low SNR and limited training numbers. The results show that the validity and superiority of the proposed algorithm in building indoor environment.

Abstract: With the rapid development of wireless communication technology, the shortage of spectrum resources is becoming more and more serious, and may even become a bottleneck restricting of the development wireless communication technology in the future. Now, Spectrum sensing technology, spectrum sharing technology and spectrum management technology is the three core technologies of cognitive radio spectrum,and sensing technology is to implement the follow-up of spectrum sharing and the premise of spectrum management.So mainly to the current model of the cognitive radio spectrum sensing technology,to make a classification and comparison, finally it is concluded that cognitive users under the environment of higher signal-to-noise ratio, the better results of the perceived performance.