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In this paper, we propose a generalized method of high-level three dimensional (3D) signal constellation mapping based on the most basic 3D structure: regular tetrahedron cells. First, we redefined the waveform design, the normalized frequency and phase modulation for the geometric construction of tetrahedron cells. Then, the new topology of tetrahedron(More)
First-principles density functional theory (DFT) simulations were carried out to study the strain dependence on the electronic and optical properties of cadmium selenide (CdSe) nanowires (NWs). The band structures, effective masses of electron and holes, dielectric properties, and other optical properties (such as extinction coefficient, optical(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)
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)
Constellation mapping has provided a great convenience to measure the performance of digital signal modulation in Euclid space. However, traditional in-phase and quadrature (IQ) plane is difficult to express the frequency modulation scheme such as minimum shift keying (MSK) and the time domain modulation such as cyclic code shift keying (CCSK). How to(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)
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)