Browsing by Subject "Phase noise"

Now showing 1 - 8 of 8

Open Access
5G PDSCH: performance analysis of DMRS and PTRS designs for channel and phase noise estimation in MM-WAVE
(2021-08) Pekcan, Doğan Kutay
The mm-Wave is one of the main enablers for the performance requirements of 5G. Although it provides communication systems with huge bandwidth and data rates, it also has some disadvantages as the carrier frequencies can significantly exceed 6 GHz and go up to 300 GHz. For example, there are significant challenges such as propagation loss and severe phase noise (PN). The PN can be observed in two parts: common phase error (CPE) and inter-carrier interference (ICI). In the literature, there are algorithms for the estimation and compensation of PN for OFDM-based systems. We apply both CPE and ICI compensation algorithms for 5G PDSCH at the carrier frequency of 70 GHz. Detailed performance analysis is performed for demodulation reference signal (DMRS) based channel estimation and phase-tracking reference signal (PTRS) based PN estimation. We observe the effects of different reference signal parameters in 5G for each PN compensation algorithm. For this purpose, we use up-to-date power spectral density (PSD) models for PN modeling and show uncoded bit error rate (BER) graphs obtained via extensive simulations for MATLAB's tapped delay line (TDL) channels. We also analyze the system performance under very high Doppler, where PTRS based channel estimation is compared with DMRS based channel estimation.
Open Access
Autofocused spotlight SAR image reconstruction of off-grid sparse scenes
(Institute of Electrical and Electronics Engineers Inc., 2017) Camlıca, S.; Gurbuz, A. C.; Arıkan, Orhan
Synthetic aperture radar (SAR) has significant role in remote sensing. Phase errors due to uncompensated platform motion, measurement model mismatch, and measurement noise can cause degradations in SAR image reconstruction. For efficient processing of the measurements, image plane is discretized and autofocusing algorithms on this discrete grid are employed. However, in addition to the platform motion errors, the reflectors, which are not exactly on the reconstruction grid, also degrade the image quality. This is called the off-grid target problem. In this paper, a sparsity-based technique is developed for autofocused spotlight SAR image reconstruction that can correct phase errors due to uncompensated platform motion and provide robust images in the presence of off-grid targets. The proposed orthogonal matching pursuit-based reconstruction technique uses gradient descent parameter updates with built in autofocus. The technique can reconstruct high-quality images by using sub Nyquist rate of sampling on the reflected signals at the receiver. The results obtained using both simulated and real SAR system data show that the proposed technique provides higher quality reconstructions over alternative techniques in terms of commonly used performance metrics.
Open Access
Blind data detection in the presence of PLL phase noise by sequential Monte Carlo method
(IEEE, 2006-06) Panayırcı, Erdal; Çırpan H. A.; Moeneclaey, M.; Noels, N.
In this paper, based on a sequential Monte Carlo method, a computationally efficient algorithm is presented for blind data detection in the presence of residual phase noise generated at the output the phase tracking loop employed in a digital receiver. The basic idea is to treat the transmitted symbols as" missing data" and draw samples sequentially of them based on the observed signal samples up to time t. This way, the Bayesian estimates of the phase noise and the incoming data are obtained through these samples, sequentially drawn,together with their importance weights. The proposed receiver structure is seen to be ideally suited for high-speed parallel implementation using VLSI technology. © 2006 IEEE.
Open Access
Blind phase noise estimation in OFDM systems by sequential Monte Carlo method
(Springer, 2006) Panayırcı, Erdal; Çırpan, H. A.; Moeneclaey, M.; Noels, N.
In this paper, based on a sequential Monte Carlo method, a computationally efficient algorithm is presented for estimating the residual phase noise, blindly, generated at the output the phase tracking loop employed in OFDM systems. The basic idea is to treat the transmitted symbols as "missing data" and draw samples sequentially of them based on the observed signal samples up to time t. This way, the Bayesian estimates of the phase noise is obtained through these samples, sequentially drawn, together with their importance weights. The proposed receiver structure is seen to be ideally suited for high-speed parallel implementation using VLSI technology.
Open Access
Cross-coupled CMOS voltage controlled oscillators operating in the X-band
(2023-06) Soygür, Can
Voltage controlled oscillators (VCOs) are electronic devices whose oscillation frequencies can be tuned by applying an external control input. A widely preferred topology is the cross-coupled VCO topology, which offers easy implementation inside integrated circuits. VCO designers take certain performance metrics into account for their designs, with the most prominent ones being the frequency tuning range and the output phase noise. These two metrics often require trading off from one another; as introducing more networks for tunability increases the overall noise within the device. With the aim of observing this trade-off between the tuning range and phase noise, four VCOs have been designed and fabricated in a single die with a 0.18 µm CMOS process. They are designed to operate in the X-band, at almost the same oscillation frequencies, to allow for easier comparison. Each VCO in the IC offers either more tunability with more tuning circuits or better phase noise performance with simpler circuits. Measurement results verify this hypothesis; a decrease in output phase noise is observed in the tested VCOs that contained simpler tuning network. With center frequencies of oscillation at approximately 12 GHz in the VCOs, tuning ranges as high as 25% are achieved in the VCO with most tunability, while phase noises as low as -106 dBm/Hz (at a 1 MHz offset) were achieved in the one with no tunability.
Open Access
Development of fiber optical delay line based 10 GHZ phase noise measurement system
(2019-02) Paray, Bilgehan
Microwave photonics is an emerging field of study exploiting broadband, low loss photonics technology for high spectral purity microwave generation, processing and distribution. Fiber optical delay lines are such systems employed successfully for generation and phase noise analysis of microwave signals with high spectral purity. Low loss and wide bandwidth of the fiber optical delay line permits much larger delays to be realized at a reasonable loss at microwave frequencies. In this study, fiber optical delay line based frequency discriminator phase noise measurement system is designed and implemented to resolve ultra low phase noise spectra of optoelectronic oscillators. System design is described in detail including fiber optical and microwave component characterizations, selection criteria, system stabilization against environmental uctuations and system calibration. Phase noise measurements for various RF synthesizers available in the laboratory are conducted with the developed system and compared to spectrum analyzer phase noise measurements to validate system calibration. Finally, phase noise spectra of optoelectronic oscillators (OEO) with 1 km and 2 km delay elements are demonstrated with the developed system. With 2 km OEO, system can resolve phase noise spectra as low as -140 dBc=Hz at 10 kHz offset from 10 GHz carrier frequency.
Open Access
High-precision laser master oscillators for optical timing distribution systems in future light sources
(European Physical Society Accelerator Group (EPS-AG), 2006) Winter, A.; Schmüser, P.; Ludwig, F.; Schlarb, H.; Chen, J.; Kärtner, F. X.; ilday, F. ÖMER
An ultra-stable timing and synchronization system for linac-driven FELs has been designed providing 10 fs precision over distances of several kilometers. Mode-locked fiber lasers serve as master oscillators. The optical pulse train is distributed through length-stabilized fiber links. The layout of the optical synchronization system and its phase noise properties are described. A prototype system has been tested in an accelerator environment and has achieved the required stability.
Open Access
Numerical analysis of multidomain systems: coupled nonlinear PDEs and DAEs with noise
(Institute of Electrical and Electronics Engineers, 2018) Demir, A.; Hanay, Selim
We present a numerical modeling and simulation paradigm for multidomain, multiphysics systems with components modeled both in a lumped and distributed manner. The lumped components are modeled with a system of differential-Algebraic equations (DAEs), whereas the possibly nonlinear distributed components that may belong to different physical domains are modeled using partial differential equations (PDEs) with associated boundary conditions. We address a comprehensive suite of problems for nonlinear coupled DAE-PDE systems including 1) transient simulation; 2) periodic steady-state (PSS) analysis formulated as a mixed boundary value problem that is solved with a hierarchical spectral collocation technique based on a joint Fourier-Chebyshev representation, for both forced and autonomous systems; 3) Floquet theory and analysis for coupled linear periodically time-varying DAE-PDE systems; 4) phase noise analysis for multidomain oscillators; and 5) efficient parameter sweeps for PSS and noise analyses based on first-order and pseudo-Arclength continuation schemes. All of these techniques, implemented in a prototype simulator, are applied to a substantial case study: A multidomain feedback oscillator composed of distributed and lumped components in two physical domains, namely, a nano-mechanical beam resonator operating in the nonlinear regime, an electrical delay line, an electronic amplifier and a sensor-Actuator for the transduction between the two physical domains.