Yongxin Feng

An Energy-Efficient Routing Protocol Based Dynamic Cooperative MIMO for Wireless Sensor Network

WSN network is energy constrained, the energy consumption of the network has stringent limited. During design routing protocols, Energy issues is important factors to be considered. Without increasing send energy of nodes, MIMO technology can make use of the cumulative energy of the sending node to increase the sending signal to noise ratio, thus reducing the error rate and improve the reliability of data communication, In the same transmit power and bit error rate situations, Using MIMO technology can provide higher data rates, reducing the node sending time, thereby reducing the forward node processing and communication cost. In this paper, Based on dynamic collaborative virtual antenna MIMO technology, a new energy efficient routing protocol is proposed. In the specific application environment, Simulation shows that the protocol has better energy efficiency.

The Research of Acquiring BOC Signal in Navigation System

An algorithm is simulated and researched for direct acquiring PRN code based on the technology of band pass signal sub-sampling, utilizing the auto-correlation characteristic of the long period PRN code in BOC modulation. The algorithm is simulated and its performance is analyzed with decreasing Signal-to-Noise. The validity of the algorithm with the lower SNR is proved by simulation under band pass sub-sampling. The number of computing data is much less, because of the lower sampling frequency.

The Research of Side-Band Acquisition for BOC-Modulated Signal

Binary Offset Carrier modulation has the special character of splitting spectrum, but usually each band of the spectrum has the information for demodulation, in a sense that each band is redundant to another, so the receiver can process only one of them. Because the correlation function is the most important for the acquisition stage of the receiver, so, as an example, The analytic formula of power spectral density function and autocorrelation function for BOC (8,4) are deduced at first in this paper, then base on them, the FFT algorithms is chosen for the side-band acquisition of the BOC-modulated signal, through the simulation and analytic, the feasibility of this acquisition scheme is validated at last.

A security model of command and control system based on SOA

The command and control system based on SOA exists frangibility for information exchange, which has become a bottleneck to limit the development of them. A security policy of information exchange for command and control system is established, which combines with AES encryption, RSA digital signatures and authentication. The simulation results show that this policy ensures the security of the interactive information and improves the efficiency of information security process time.

Research on GNSS Simulation System Based on Alterable Time Granularity

The Global Navigation Satellite System(GNSS) is a high precision navigation system based on satellite, which implements worldwide, all-weather, real-time, continuous navigation and position. It is very necessary to establish a rational and flexible simulation system of GNSS, which can help to analyse the characteristics of GNSS and research on technologies of the GNSS receiver, jamming and anti-jamming etc. A GNSS simulation model is presented, which adopts a time management strategy based on time step to complete simulation synchronization and implement the simulation of GNSS effectively.

The Research on Packets Multiplexing Efficiency Based on AOS Space Data Link Protocol

The MPDU multiplexing was taken as the first phase of the multiplexing mechanism of CCSDS, whose efficiency was bound up with transmission performance and capability of valid data on advanced orbiting systems. Based on model of forming frame with Poisson distribution and invariable packet and slot, the concept of high order of residual function was presented and the formula of MPDU multiplexing efficiency was given. The simulation results showed that the experimental simulation validated the theoretical curves very well with the higher order of residual function.

A Classification Detection Algorithm Based on Joint Entropy Vector against Application-Layer DDoS Attack

The application-layer distributed denial of service (AL-DDoS) attack makes a great threat against cyberspace security. The attack detection is an important part of the security protection, which provides effective support for defense system through the rapid and accurate identification of attacks. According to the attacker’s different URL of the Web service, the AL-DDoS attack is divided into three categories, including a random URL attack and a fixed and a traverse one. In order to realize identification of attacks, a mapping matrix of the joint entropy vector is constructed. By defining and computing the value of EUPI and jEIPU, a visual coordinate discrimination diagram of entropy vector is proposed, which also realizes data dimension reduction from to two. In terms of boundary discrimination and the region where the entropy vectors fall in, the class of AL-DDoS attack can be distinguished. Through the study of training data set and classification, the results show that the novel algorithm can effectively distinguish the web server DDoS attack from normal burst traffic.

The configuration of a flexible control binary offset carrier modulation signal

Along with the fast development of spread spectrum communication and global positioning system, varied signal forms are proposed, especially the emergence of BOC modulated signal leads to the characteristics of multi peaks and spectrum splitting. However, consider the need for the flexibility and extensible BOC signals application, a flexible control binary offset carrier modulation signal is proposed in this paper. Based on the BOC modulation signal, the control parameter is defined in the new signal, and the flexible single period subcarrier sequence is generated by configuring the control parameter. Further, the single period subcarrier sequence is periodically expanded to get the subcarrier, which is modulated by PRN code to get FC-BOC signal. This signal has the dynamic and flexibility of the spectrum and correlation function, and can provide a reference for the application of the new generation of spread spectrum signal and navigation signal.

An Accurate Modulation Recognition Method of QPSK Signal

Quadrature phase shift keying (QPSK) modulation has been widely applied in communication systems. With the increasing development of QPSK modulation recognition, it is meaningful for ensuring validity and accuracy of recognition method. Therefore, the method of signal recognition has been presented based on the features of QPSK modulated signal, in which the feature parameters of QPSK signal are extracted. Besides, signal classification is fulfilled through thresholds, and modulation recognition is completed with quartic spectrum. The simulation results show that, the method can recognize QPSK modulation effectively in less sample space condition and can be more accurate.

Research on the method of separating differential frequency hopping signal based on JADE

The wireless transmission mode of difference frequency hopping signal causes that it will include jamming signal in the received signal, and it will affect the correct receiving of the DFH signal. Based on studying the mechanism and characteristics of DFH signal, and utilizing the statistical independence, a method is proposed for separating DFH signal in mixing signals by JADE. The proposed method is simulated. The simulation result shows that the proposed method can effectively separate the DFH signal in the mixed signals.