Zheng Dou

Dynamic threshold-setting for RF-powered cognitive radio networks in non-Gaussian noise

Abstract The increasing demand for spectral and energy efficient communication networks has drawn an upsurge of interest in frequency (RF) energy harvesting (EH) cognitive radio networks (CRNs), and the spectrum analyzer is the brain to provide different spectral access and energy harvesting opportunities in wireless-powered cognitive radio networks (WP-CRNs). The performance of detecting the existence of primary signals will be more crucial for the EH node. However, to the best of our knowledge, no dynamic threshold-setting method to achieve target detection performance, particularly in the practical non-Gaussian noise, is reported in the literature. Traditional assumption of additive white Gaussian noise (AWGN) fails to model the behavior of certain types of noise found in practice. In this paper we give a dynamic threshold-setting method to detect the existence of primary signals for the energy harvesting node in non-Gaussian noise background. Combined with the fractional lower order statistics (FLOS), we propose a weighting factor for dynamic threshold-setting to exploit the existence of the PU to harvest RF energy, namely weighting factor based fractional lower order moment (WF-FLOM) detector. Numerical simulation results verify that the proposed method is effective for the EH node, when the signal-to-noise ratio is low or the back ground noise varies.

The comparison of several kinds of time-frequency analysis methods

In this paper, the author introduces three useful linear time-frequency analysis methods: short-time Fourier transform(STFT), wavelet transform(WT), S transform(ST) and generalized S transform(GST). Then, algorithm simulations are conducted using these four methods to show their advantage and disadvantage.

Automatic recognition of communication signal modulation based on neural network

In order to solve the problem of low modulation recognition rate of digital communication signals and the difficulty of selecting the appropriate decision threshold, the paper features a recognition method for communication signal modulation. The paper constructs characteristic parameters for recognizing signals in the cyclic frequency domain, and uses a 3-layer neural network as a classifier to identify the modulation mode. The experiment indicates that it can recognize 2FSK, 4FSK, 8FSK, BPSK, QPSK, MSK and 2ASK When signal to noise ratio (SNR) is higher than 0 dB, the recognition rate achieves 95%. The results suggest that recognition of communication signal modulation based on neural network is accurate and feasible.

An optimal design of time division multiple access protocol for data link network

A Tactical Data Link(TDL) uses a data link standard in order to provide communication via radio waves or cable. All military C3 systems use standardized TDL to transmit, relay and receive tactical data. Data link technology is the core technology of modern information war, it can provide unified interactive communication for combat system and weapon equipment. In order to improve the performance of data link, one of the key technologies is reasonable allocation of bandwidth resources at the MAC layer. And TDMA protocol is one of the commonly used MAC protocols in data link system. This article introduces an application of Time Division Multiple Access(TDMA) technology to tactical data link described in this paper. In this paper, we propose a method that adds the interrupt time slot to decrease the delay of the communication network on the basis of fixed time slot scheduling. Simulation results show that this method is less time delay and improves the performance of network.

Application of FFT parallel code phase search algorithm in GNSS software

With the rapid development of software radio, the research and design of Global Navigation Satellite System(GNSS) software receiver has become a hot research topic in the whole satellite navigation system. In this paper, a new signal acquisition algorithm based on FFT parallel code phase search is proposed, which is based on the research of the base-band signal processing method in GNSS software receiver, the design structure of code tracking loop and carrier tracking loop is presented, and the realization method and function are analyzed and simulated. Computer simulation results show that the FFT parallel code phase search algorithm and the PLL loop algorithm in the DLL loop and FLL loop can get very good performance. The software receiver can modify the software program to achieve GNSS receiver related functions and improve technical indicators without making changes in the hardware platform, it is suitable for engineering applications.

Low complexity and narrow transition band filter banks for software defined radio applications

We presented an improved efficient architecture of low complexity and narrow transition band filter banks for software defined radio applications. A drawback in filter banks is that the narrow transition band filter is designed with high computation complexity. In order to get around this problem, this paper shows how the filter banks architecture can be designed with low complexity by using frequency response masking technology. We derives efficient architecture of exponentially modulated filter banks based the theory of polyphase, and uses frequency response masking technology to design narrow transition band filter. With employed this method we can extract uniform bandwidths and very narrow bandwidth channels compared to polyphase filter banks. A simulation is provided to illustrate the method of the proposed filter banks architecture. It is shown that the resulting filter banks entail substantially less computational complexity compared to the polyphase filter banks.

Simulation research and implementation of optimal jamming effect on MSK signal

With the rapid development of communication technology, digital communication has become the main way of information transmission. MSK signal has the advantages of continuous phase, constant envelope and so on. It has been widely used, so it is very important to select the best jamming pattern for MSK signal. In this paper, we analyze all kinds of jamming patterns of MSK signal, and simulate the model by Matlab. Finally, the bit error rate curves of MSK signals under different jamming modes are obtained.

Small particle reconstruction method via SCA

With the continuous development of software defined radio(SDR) technology, the hunger for the reconstruction performance of the SDR system is getting higher and higher, especially in the area of effective small scale reconstruction. As we all know, software communication architecture(SCA) is a mature development framework for SDR, and the small scale reconstruction via SCA is a challenge currently. In this paper, we propose a small particle reconstruction methods based on the general method of reconstruction for SDR, which improves the reconstruction ability by the way to make the waveform component granular and some of them can be switched if needed.

Design of VHF channel simulator based on SDR platform

The research and application of ultrashort wave are more and more wide ultrashort wave communication has become an indispensable communication way in the field of modern communication, especially in military communication. Based on the needs of ultrashort wave wireless communications technology development, this paper gives theoretical analysis and simulation verification on channel characteristics of ultrashort wave, and gives the VHF channel simulator implementation scheme on the software defined radio platform. This paper views the background and research significance of the ultrashort wave channel transmission characteristics and has research on channel transmission characteristics such as the multipath transmission delay, Doppler shift frequency expansion, large-scale fading. Through analysis and comparison of the channel model, this paper chooses the irregular terrestrial transmission channel model weighted small-scale fading model as the primary model. This project gives the theoretical simulation based on the actual needs of the project.

A secret communication system via SD-SMSE

Setting up a communication system should also pay attention to both security and concealment in addition to the validity and reliability of the information, especially in military communication. In this paper, we introduce an application of the SD-SMSE framework under the secret communication, and the application combines overlay and underlay access with encryption. At the receiving end, we use the received key to restore the original information from the received encrypted information. The simulation results approve the feasibility of the framework under the given new application, which improves the utilization of spectrum and ensures the security of communication.