4,877 research outputs found
A new coupling solution for G3-PLC employment in MV smart grids
This paper proposes a new coupling solution for transmitting narrowband multicarrier power line communication (PLC) signals over medium voltage (MV) power lines. The proposed system is based on an innovative PLC coupling principle, patented by the authors, which exploits the capacitive divider embedded in voltage detecting systems (VDS) already installed inside the MV switchboard. Thus, no dedicated couplers have to be installed and no switchboard modifications or energy interruptions are needed. This allows a significant cost reduction of MV PLC implementation. A first prototype of the proposed coupling system was presented in previous papers: it had a 15 kHz bandwidth useful to couple single carrier PSK modulated PLC signals with a center frequency from 50–200 kHz. In this paper, a new prototype is developed with a larger bandwidth, up to 164 kHz, thus allowing to couple multicarrier G3-PLC signals using orthogonal frequency division multiplexing (OFDM) digital modulation. This modulation ensures a more robust communication even in harsh power line channels. In the paper, the new coupling system design is described in detail. A new procedure is presented for tuning the coupling system parameters at first installation in a generic MV switchboard. Finally, laboratory and in-field experimental test results are reported and discussed. The coupling performances are evaluated measuring the throughput and success rate in the case of both 18 and 36 subcarriers, in one of the different tone masks standardized for the FCC-above CENELEC band (that is, from 154.6875–487.5 kHz). The experimental results show an efficient behavior of the proposed coupler allowing a two-way communication of G3-PLC OFDM signals on MV networks
Measured pedestrian movement and bodyworn terminal effects for the indoor channel at 5.2 GHz
[Summary]: Human body effects such as antenna-body interaction and scattering caused by pedestrian movement are important indoor radio propagation phenomena at microwave frequencies. This paper reports measurements and statistical analysis of the indoor narrowband propagation channel at 5.2 GHz for two scenarios: a fixed line-of-sight (LOS) link perturbed by pedestrian movement and a mobile link incorporating a moving bodyworn terminal. Two indoor environments were considered for both types of measurements: an 18 m long corridor and a 42 m2 office. The fixed-link results show that the statistical distribution of the received envelope was dependent on the number of pedestrians present. However, fading was slower than expected, with an average fade duration of more than 100 ms for a Doppler frequency of 8.67 Hz. For the bodyworn terminal, mean received power values were dependent on whether or not the user's body obstructed the LOS. For example, in the corridor the average non-line-of-sight (NLOS) pathloss was 5.4 dB greater than with LO
Frequency tuning of a triply-resonant whispering-gallery mode resonator to MHz wide transitions for proposed quantum repeater schemes
Quantum repeaters rely on an interfacing of flying qubits with quantum
memories. The most common implementations include a narrowband single photon
matched in bandwidth and central frequency to an atomic system. Previously, we
demonstrated the compatibility of our versatile source of heralded single
photons, which is based on parametric down-conversion in a triply-resonant
whispering-gallery mode resonator, with alkaline transitions [Schunk et al.,
Optica 2, 773 (2015)]. In this paper, we analyze our source in terms of phase
matching, available wavelength-tuning mechanisms, and applications to
narrow-band atomic systems. We resonantly address the D1 transitions of cesium
and rubidium with this optical parametric oscillator pumped above its
oscillation threshold. Below threshold, the efficient coupling of single
photons to atomic transitions heralded by single telecom-band photons is
demonstrated. Finally, we present an accurate analytical description of our
observations. Providing the demonstrated flexibility in connecting various
atomic transitions with telecom wavelengths, we show a promising approach to
realize an essential building block for quantum repeaters.Comment: 18 pages, 14 figure
Measurement and Characterization of the Stationary Noise in Narrowband Power Line Communication
Understanding the interference scenario in power lines network is a key step
to characterize the power line communication (PLC) system. This paper focuses
on the characterization and modelling of the stationary noise in Narrowband
PLC. Measurement and analysis of noise is carried out in the Tunisian outdoor
Low Voltage (LV) power line network in the frequency band below 500 kHz. Based
on existing models and measurements results, a parametric model of noise is
proposed; the model parameters are statistically studied.Comment: 11th International Conference on Networks & Communications (NeTCoM
2019
A fully integrated 24-GHz phased-array transmitter in CMOS
This paper presents the first fully integrated 24-GHz phased-array transmitter designed using 0.18-/spl mu/m CMOS transistors. The four-element array includes four on-chip CMOS power amplifiers, with outputs matched to 50 /spl Omega/, that are each capable of generating up to 14.5 dBm of output power at 24 GHz. The heterodyne transmitter has a two-step quadrature up-conversion architecture with local oscillator (LO) frequencies of 4.8 and 19.2 GHz, which are generated by an on-chip frequency synthesizer. Four-bit LO path phase shifting is implemented in each element at 19.2 GHz, and the transmitter achieves a peak-to-null ratio of 23 dB with raw beam-steering resolution of 7/spl deg/ for radiation normal to the array. The transmitter can support data rates of 500 Mb/s on each channel (with BPSK modulation) and occupies 6.8 mm /spl times/ 2.1 mm of die area
Reciprocity Calibration for Massive MIMO: Proposal, Modeling and Validation
This paper presents a mutual coupling based calibration method for
time-division-duplex massive MIMO systems, which enables downlink precoding
based on uplink channel estimates. The entire calibration procedure is carried
out solely at the base station (BS) side by sounding all BS antenna pairs. An
Expectation-Maximization (EM) algorithm is derived, which processes the
measured channels in order to estimate calibration coefficients. The EM
algorithm outperforms current state-of-the-art narrow-band calibration schemes
in a mean squared error (MSE) and sum-rate capacity sense. Like its
predecessors, the EM algorithm is general in the sense that it is not only
suitable to calibrate a co-located massive MIMO BS, but also very suitable for
calibrating multiple BSs in distributed MIMO systems.
The proposed method is validated with experimental evidence obtained from a
massive MIMO testbed. In addition, we address the estimated narrow-band
calibration coefficients as a stochastic process across frequency, and study
the subspace of this process based on measurement data. With the insights of
this study, we propose an estimator which exploits the structure of the process
in order to reduce the calibration error across frequency. A model for the
calibration error is also proposed based on the asymptotic properties of the
estimator, and is validated with measurement results.Comment: Submitted to IEEE Transactions on Wireless Communications,
21/Feb/201
Power line communication impedance profiling and matching for broadband applications.
Masters Degree. University of KwaZulu-Natal, Durban.Power line communication(PLC) is a wired communication technology that has recently re-
ceived a lot of attention due to its attractive prospects towards home and /or neighborhood network
applications as well as smart grid technologies. It allows establishing digital com- munications
without any additional wiring requirements. Effectively, one’s home and/or neighborhood wiring
contributes into a smart grid to deploy various data services. It is well known that the
power grid is one of the most pervasive infrastructure built to provide electricity to customers,
therefore, utilizing this infrastructure for digital communications will only result in an
ubiquitous telecommunications network. It is common practice to use wires to establish a physical
connection in many telecommunications channels, but most electronic devices already have a
pair of wires connected to the power lines. Therefore, these wires can be used to
simultaneously establish digital communications. Thus, power line communications can be used as an
alternative solution to more established technologies such as wireless, coaxial and optical
communications. As a promising technology, PLC has attracted a lot of research and has become an
active area of research which continues to evolve over time. Notwithstanding its advantages, PLC
has issues, namely, severe noise at low frequencies and varying characteristic impedance. This is
primarily because the power line channel was not originally designed to be used for communications,
thus, it remains a harsh channel. Other challenges arise from the fact that there are
different wiring practices around the world, unpredictable loading characteristics as well
as differential- and common-mode characteristic impedance. As a result, there is a considerable
amount of noise signal attenuation during data transmission. Loss of signal can be
addressed by increasing the power at the transmitter, noise reduction and/or reducing
channel attenuation to improve the signal-to-noise ratio. However, PLC modems are
subject to legislation that impose a limit with regards to the signal levels in the
lines. Power lines are good radiators at high frequencies which makes them behave like large
antennas with the ability to intercept other radiations in the same frequency range. The radiated
signal is proportional to the currents in the line, thus, increasing line currents will
not solve the problem but would rather lead to violation of electromagnetic
compatibility (EMC)
regulations.
In this work, an alternative solution is provided which seeks to address the issue of signal
attenuation caused by the changing input impedance of a typical power line channel. The
deleterious effects of noise are not considered since this work focuses on broadband
PLC in the 1–30 MHz frequency range. The objective of this work was to design and
build an impedance adaptive coupler to mitigate effects of channel attenuation caused by varying
impedance. In this way, the propagating signal will “see” a uniform impedance and as a
result the data output will be improved. The work was facilitated by measuring several impedance
profiles of PLC channels in the band of interest. Typically, the network topology of PLC
networks is not known and the building architectural blueprints are
not always readily available. To overcome this issue,this work was performed on power
line test-beds designed to mimic varied typical PLC network topologies. Moreover, there is an
additional benefit in that it is possible to relate the output impedance profile to
the network topology. The channel input impedance characteristics were determined in a
deterministic manner by considering a power line network as a cascade of parallel
resonant circuits and applying transmission line theory to develop the model. The
model was validated by measurements with good agreement over the frequency range was considered.
Several measurements were then used to determine the minimum, average and maximum input
impedance that a signal will experience as it traverses the channel. It was found that,
regardless of the network size (in terms of number of branches), the average input
impedance is 354 ± 1.1 % Ω in the 1-30 MHz frequency band. Due to the
unpredictable nature of the input impedance of the power line network, an impedance adaptive
bidirectional coupler for broadband power line communications was designed. The impedance
matching is achieved by using typical L-section matching networks in the 1–30 MHz band.
The matching section of the coupler has the characteristics of a lowpass filter while
the coupling section is a highpass filter, effectively forming a bandpass network. The simulated
transfer characteristics of the designed coupler performs very well for impedances starting around
150 Ω and the performance improves a great deal as the impedance increases. The coupler can still
be improved to accommodate much lower input impedances (as low as 50 Ω). However, based on the
measured results of input impedance, it was observed that the power line channel impedance is
statistically higher than 200 Ω most of the time which makes the presented design acceptable
Characterization and Emulation of Low-Voltage Power Line Channels for Narrowband and Broadband Communication
The demand for smart grid and smart home applications has raised the recent interest in power line communication (PLC) technologies, and has driven a broad set of deep surveys in low-voltage (LV) power line channels. This book proposes a set of novel approaches, to characterize and to emulate LV power line channels in the frequency range from0.15to 10 MHz, which closes gaps between the traditional narrowband (up to 500 kHz) and broadband (above1.8 MHz) ranges
Characterization and Emulation of Low-Voltage Power Line Channels for Narrowband and Broadband Communication
The demand for smart grid and smart home applications has raised the recent interest in power line communication (PLC) technologies, and has driven a broad set of deep surveys in low-voltage (LV) power line channels. This book proposes a set of novel approaches, to characterize and to emulate LV power line channels in the frequency range from0.15to 10 MHz, which closes gaps between the traditional narrowband (up to 500 kHz) and broadband (above1.8 MHz) ranges
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