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Continuous Phase Modulation Format Optical Systems
Published in Le Nguyen Binh, Advanced Digital, 2017
Recent years have witnessed intensive interest in the employment of advanced modulation formats to explore their advantages and performance in high-density and long-haul transmission systems. Return-to-zero (RZ) and non-return-to-zero (NRZ) without or with carrier suppression (CSRZ) formats are associated with shift keying (SK) modulation schemes such as amplitude (ASK), phase (PSK), and differential phase (DPSK, DQPSK) [1,2]. Differential detection offers the best technological implementation owing to the nonrequirement of coherent sources and avoidance of polarization control of the mixing of the signals and a local oscillator in the multi-THz frequency range. Continuous phase modulation (CPM) is also another form of phase shift keying (PSK) in which the phase of the optical carrier evolves continuously from one phase state to the other. For MSK, the phase change is limited to π/2. Although MSK is a well-known modulation format in radio frequency digital communications, it has only been attracting interest in optical system research in the past few years [3–5]. The phase continuous evolution of MSK has many interesting features: the main lobe of the power spectrum is wider than that of quadrature phase shift keying (QPSK) and differential phase shift keying (DPSK) and the side lobes of the MSK signal spectrum are much lower, allowing ease of optical filtering and hence less distortion due to dispersion effects. In addition, higher signal energy is concentrated in the main lobe of MSK spectrum than its side lobes, leading to a better signal-to-noise ratio at the receiver.
Modulation Methods
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
Continuous phase modulation (CPM) refers to a broad class of FM techniques where the carrier phase varies in a continuous manner. A comprehensive treatment of CPM is provided in Reference 2. CPM schemes are attractive because they have constant envelope and excellent spectral characteristics. The complex envelope of a CPM waveform has the general form
Modulation Methods
Published in Jerry D. Gibson, The Communications Handbook, 2018
Continuous phase modulation (CPM) refers to a broad class of frequency modulation techniques where the carrier phase varies in a continuous manner. A comprehensive treatment of CPM is provided in [1]. CPM schemes are attractive because they have constant envelope and excellent spectral characteristics. The complex envelope of any CPM signal is
Adaptive clustering with continuous phase modulation in NOMA systems
Published in International Journal of Electronics, 2022
Guowei Lei, Wenqing Ni, Wenliang Liao, Sunqing Su
Our contributions to the paper are summarised as: (1) we investigate the modulation in downlink NOMA system. We propose a scheme of NOMA system with continuous phase modulation. The idea behind the scheme is to harness the inner coding of CPM and mitigate the interference among users in the system. Furthermore, we would like to derive the approximated capacity for the system over Rayleigh channel. (2) A combination of adaptive clustering and beamforming is proposed in NOMA downlink transmission according to the achievable sum-rate. The distinction to the state-of-art is that the number of clusters, and the number of users in each cluster will be uncertain. Moreover, the algorithm can be applied to any circumstances for NOMA system. (3) Under the above circumstance, the power allocations for users and clusters are studied and the achievable upper-bounds are derived hereupon.
Generation of nondiffraction beam with arbitrary focusing direction using metasurface
Published in Electromagnetics, 2020
In this paper, we design a metasurface element based on the PB phase principle (Qu et al. 2019), which can be seen in Figure 2. The unit-cell consists of a metal deformed cross constructed on the F4B substrate with a permittivity of 2.65. Structural parameters of the proposed PB unit-cell are as follows (in millimeter): W = L = 5, H = 3, L1 = 2.2, L2 = L4 = 0.9, L3 = 1.7, L5 = 0.5, W1 = 0.2. The software ANSYS high-frequency structure simulator is used in the simulation. The reflectivity and phase difference of the X- and Y-polarized waves are also displayed in Figure 2 when the element is illuminated by a right-hand circularly polarized wave. It is observed that the reflectivity of X- and Y-polarized waves is almost equal. A nearly constant 180° reflected phase difference could be achieved between the X- and Y-polarized waves (10–16 GHz). Note that |rxx| = |rYY| ≈ 1 and phase difference = 180° are two necessary conditions in PB phase principle. By this way, the arbitrary phase difference between 0 and 2π can be achieved by rotating the unit-cell angle of half of the phase factor. Namely, continuous phase modulation can be achieved through different spatial orientations of the same unit-cell structure.
Non-linear equalisation and CFO compensation for MIMO-OFDM communication systems based on DWT
Published in International Journal of Electronics, 2021
K. Ramadan, Moawad I. Dessouky, Fathi E. Abd El-Samie
The future work of this manuscript may include the following points: Application of the proposed equalisers with different configurations such as Code Division Multiple Access (CDMA), Filter Bank Multi-Carrier (FBMC), and Universal Filtered Multi-Carrier (UFMC).Application of the proposed equalisers with continuous phase modulation.Application of beamforming with the proposed equalisers.