• Citations Per Year
Learn More
Transform domain communication system (TDCS) is a potential candidate for cognitive radio (CR). It is immune to the interception and has the characteristics of high spectral utilization. Nevertheless, large peak-to-average power ratio (PAPR) of the time domain signal inherently makes TDCS particularly sensitive to nonlinear distortion caused by the high(More)
Frequency spectrum resource is the most important and fundamental resource for various information systems such as communication systems, radar systems and so on. In order to overcome the conflicts between the scarcity and low usage efficiency, cognitive capability becomes more and more important for future information system designs. In this paper, we give(More)
First, this paper analyzes the performance of the linear frequency modulation (LFM) interference in PN spread-spectrum communication systems. Second, in the light of suppressing the side-lobe of periodic LFM in fractional Fourier transform (FRFT) domain, a method combined transform-domain and time-domain is proposed, this method improves the processing gain(More)
Orthogonal Frequency Division Multiplexing (OFDM) using Fractional Fourier Transform (FrFT) normally known as Chirped OFDM is studied. The Constant Envelope of the Chirped OFDM is then obtained by phase modulation of the chirped OFDM and then its Peak to Average Power Ratio (PAPR) is analyzed. The study shows the Constant Envelope Chirped OFDM (CE-COFDM)(More)
According to astrophysical and cosmological observations, about 20 percent of the total energy in the universe is contributed by dark matter, which, within present observational limits, only exhibits gravitational interaction. Meanwhile, the Standard Model of elementary particles don’t contain such weakly-interacting constituents. To solve this mystery(More)
Compared with pseudo-noise (PN) sequences, chirp signals have obvious advantages in acquisition time and tracking performance in the field of telemetry, track, and command (TT&C) with the large Doppler tolerance. In this paper, an effective tracking loop for chirp spread spectrum communication is proposed, which can realize chirp signals modulated by(More)
Fractional Fourier transform (FRFT) has been widely used in orthogonal frequency division (OFDM) systems to combat the doubly dispersive channels. The sensitivity of the fractional order is a serious problem. In this paper, we derive the closed form of the variable order and its optimal value based on the mathematical expression in the FRFT-OFDM systems.(More)
Int J Commun Syst 2017; e3249; DOI 10.1002/dac.3249 Summary Transform domain communication system is an adaptive anti‐interference system that can dynamically generate interference‐orthogonal waveforms. As a spread spectrum system, its low spectrum efficiency limits potential practical applications. In TDCS, cyclic code shift keying is an orthogonal(More)