Topic
Keying
About: Keying is a research topic. Over the lifetime, 6598 publications have been published within this topic receiving 82943 citations.
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TL;DR: To the authors' knowledge, the ratio between the bit rate achieved and the switching frequency of the dc–dc power converter presented in this paper is the highest that can be found in the literature.
Abstract: A dc–dc power converter based on a two-phase synchronous buck converter that reproduces single-carrier digital modulation schemes by controlling the first switching harmonic of the output voltage ripple is presented in this paper. The dc–dc power converter carries out both the lighting and the transmission functionalities of visible light communication transmitters. Control of both the amplitude and the phase of sinusoidal currents injected toward high-brightness LEDs enable the use of efficient modulation schemes, such as quadrature amplitude modulation, carrierless amplitude and phase modulation, amplitude-shift keying, and phase-shift keying. These modulation schemes achieve higher spectral efficiency (i.e., more data can be transmitted using the same bandwidth) than previously proposed modulation schemes performed by visible light communication transmitters based on the use of dc–dc power converters. To the authors' knowledge, the ratio between the bit rate achieved and the switching frequency of the dc–dc power converter presented in this paper is the highest that can be found in the literature.
36 citations
TL;DR: This letter addresses the stochastic Cramer-Rao bound pertaining to the joint estimation of the carrier frequency offset, the carrier phase and the noise and signal powers of binary phase-shift keying, minimum shift keying and quaternary phase- Shift keying modulated signals corrupted by additive white circular Gaussian noise.
Abstract: This letter addresses the stochastic Cramer-Rao bound (CRB) pertaining to the joint estimation of the carrier frequency offset, the carrier phase and the noise and signal powers of binary phase-shift keying (BPSK), minimum shift keying (MSK), and quaternary phase-shift keying (QPSK) modulated signals corrupted by additive white circular Gaussian noise. Because the associated models are governed by simple Gaussian mixture distributions, an explicit expression of the Fisher information matrix is given and an explicit expression for the stochastic CRB of these four parameters are deduced. Specialized expressions for low and high SNR are presented as well. Finally, these expressions are related to the modified CRB and our proposed analytical expressions are numerically compared with the approximate expressions previously given in the literature.
36 citations
TL;DR: This letter presents a hardware-efficient phase estimation algorithm that can replace the common complex estimators for a coherent quadrature phase-shift keying transmission system.
Abstract: This letter presents a hardware-efficient phase estimation algorithm that can replace the common complex estimators for a coherent quadrature phase-shift keying transmission system.
35 citations
TL;DR: In this article, a real-time, high data-rate "model" differential phase shift keying (DPSK) communication system has been constructed and demonstrated using parametric transduction, with a 300-kHz primary frequency and a 50-kHz secondary frequency.
Abstract: Parametric transduction offers valuable advantages for underwater acoustic communications. Perhaps the most significant benefit is the fact that high directivity is achieved by means of a physically small transmit transducer. This feature may, ultimately, be employed to permit long-range, low-frequency communication using a compact source. The high directivity is desirable to combat multipath propagation and to achieve data communications in water which is shallow by comparison with range. A real-time, high data-rate "model" differential phase shift keying (DPSK) communication system has been constructed and demonstrated. This system uses parametric transduction, with a 300-kHz primary frequency and a 50-kHz secondary frequency. Experimental results show that the system can be employed to combat multipath propagation in shallow water and can achieve high data-rate text and color image transmission at 10 and 20 kb s/sup -1/ for 2-DPSK and 4-DPSK, respectively, through a transmission bandwidth of 10 kHz. The "model" system was developed to confirm performance predictions for a future, operational long-range link employing a 50-kHz primary frequency and a 5-kHz secondary frequency.
35 citations
TL;DR: In this article, a dual-wavelength photonic signal source based on stimulated Brillouin scattering is used to generate the millimeter-wave carrier signal through photomixing.
Abstract: This paper presents the design and experimental analysis of a system architecture for 60-GHz broadband wireless communications. The architecture uses a dual-wavelength photonic signal source based on stimulated Brillouin scattering to generate the millimeter-wave carrier signal through photomixing. Data is encoded onto the optical signals and is upconverted directly to the millimeter-wave carrier through a photonic upconversion process, which does not require electronic upconversion. The data is encoded onto one optical wavelength in a single-sideband fashion, which affords significant dispersion tolerance over long remoting distances compared with standard double-sideband modulation. The prototype architecture was tested at ranges of 2-30 m indoors and 78 m outdoors, demonstrating a building-to-building link. Binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK) modulation formats were tested, with BPSK data rates up to 3 Gb/s and QPSK data rates up to 2.64 Gb/s. Good bit-error ratios are demonstrated as a function of received power and range for a fixed transmit power.
35 citations