Effect Of Oscillator Phase Noise Research Articles

Modeling the Effects of Oscillator Phase Noise and Synchronization on Multistatic SAR Tomography

Recent results have highlighted the potential ability of bi- and multistatic synthetic aperture radar (SAR) tomographers to measure vegetation structure and surface topography. However, the quality of SAR tomographic measurements with multiple platforms is impacted by the phase instability in each platform’s oscillator. The phase noise, if uncompensated, may lead to degradation in the SAR data products such as increased sidelobe levels, reduced peak amplitude of the impulse response, and a low frequency phase modulation, among others. In this work, we model and examine the effects of oscillator phase noise on tomographic SAR signals for spaceborne missions flying in formation. A synchronization process is also adopted to help mitigate oscillator phase errors by measuring and predicting relative phase offsets at prescribed temporal intervals. A simulation tool was developed to examine the point target response as seen by realistic satellite constellations in low Earth orbit using different quality oscillators, radar configurations, and synchronization configurations. A first analysis of a multi-platform tomographic SAR mission suggests that a system without a dedicated physical link with minimal effects on the point target response may be achievable using current oscillators. Our analysis also shows that phase noise has differing effects on multistatic radar modes. Tomograms formed with a system operating in SIMO mode are the most affected by oscillator phase noise error, followed by MIMO, with negligible effects on the SAR-SISO mode. These trade studies and the simulation tool can be used to help inform the design of future multistatic radar missions.

Multiuser-MISO Precoding Under Channel Phase Uncertainty in Satellite Communication Systems

Linear and symbol-level precoding in satellite communications have received increasing research attention thanks to their ability to tackle inter-beam interference, allowing the use of spectral resources more efficiently. However, there are still challenges and open questions regarding the implementation of practical precoding systems taking the phase uncertainties in estimating the channel state information into account. This work assesses the impact of phase variations and uncertainties inherent to the satellite communication system operating a precoded forward link. Specifically, we address the inability to measure at the user terminal, the absolute phase rotation introduced by the channel, and the transponder local oscillator phase noise effects on the precoding operations considering the use of frequency division multiplexing in the forward-uplink transmission. We formally demonstrate that the system performance for linear and non-linear precoding operations is not affected by the uncertainty in the phase measurements at the user terminal. Additionally, we show that using a single frequency reference for all the local oscillators at the transponder does not avoid the phase variations related to the frequency division multiplexing in the forward-uplink. This work demonstrates that these phase variations would not affect the system performance for an ideal zero-delay precoding loop. However, this is not feasible in practical scenarios, where the phase noise of the frequency reference at the transponder and the loop delay determine the impact on the system performance. We validate our results by simulations considering three frequency references with different stability levels in a typical geosynchronous orbit (GEO) satellite system. Our results suggest that practical implementations of multiuser-MISO precoding systems must include a differential phase synchronization loop to compensate for this performance degradation.

Modelling an oscillator phase noise whose spectral density contains both 1/f 2 and 1/f 3 regions

This paper introduces a new equation for modelling the phase noise spectrum of an oscillator. The new equation can model both of 1/f2 and 1/f3 regions in a phase noise spectrum. To verify the model and show its effectiveness, a mathematical analysis is performed on the effect of the oscillator phase noise on the performance of a continuous-time delta-sigma modulator. By comparing the results from the mathematical analysis with those from the Simulink simulation results, it is shown that using the proposed equation can properly predict the effect of oscillator phase noise on the modulator performance.

Effects of Oscillator Phase Noise on Frequency Delta Sigma Modulators with a High Oversampling Ratio for Sensor Applications

Effects of Oscillator Phase Noise on Frequency Delta Sigma Modulators with a High Oversampling Ratio for Sensor Applications

Analysis of oscillator phase noise effect on high order QAM links

In this work, the effect of oscillator phase noise on the bit error rate (BER) for high order QAM communication systems is analyzed. Two high frequency oscillators are designed, built and tested to get real phase noise data, and a BER simulation of a 1024 QAM signal through a super-heterodyne frequency down-converter is implemented using the measured data from the two oscillators as local oscillator sources for the down-converter. A third frequency source is also added to the simulation to visualize the dramatic effect of phase noise on the system BER analysis.

Phase Noise in Modular Millimeter Wave Massive MIMO

This paper investigates the effect of oscillator phase noise on a multiuser millimeter wave (mmWave) massive MIMO uplink as we scale up the number of base station antennas, fixing the load factor, defined as the ratio of the number of simultaneous users to the number of base station antennas. We consider a modular approach in which the base station employs an array of subarrays, or “tiles.” Each tile supports a fixed number of antennas, and can therefore be implemented using a separate radio frequency integrated circuit (RFIC), with synchronization across tiles accomplished by employing a phased locked loop in each tile to synthesize an on-chip oscillator at the carrier frequency by locking on to a common lower frequency reference clock. Assuming linear minimum mean squared error (LMMSE) multiuser detection, we provide an analytical framework that can be used to specify the required power spectral density (PSD) mask for phase noise for a target system performance. Our analysis for the phase noise at the output of the LMMSE receiver indicates two distinct effects: self-noise for each user which is inversely proportional to the number of tiles, and cross-talk between users which is insensitive to the number of tiles, and is proportional to the load factor. These analytical predictions, verified by simulations for a 140 GHz system targeting a per-user data rate of 10 Gbps, show that tiling is a robust approach for scaling. Numerical results for our proposed design approach yield relatively relaxed specifications for phase noise PSD masks.

Analysis and Correction of Combined Channel Mismatch Effects in Frequency-Interleaved ADCs

In this paper, a comprehensive system behavioral model of frequency-interleaved analog-to-digital converters (FI-ADCs) is presented. The model addresses mismatch errors due to imperfect channel separation, incomplete anti-aliasing, in-phase/quadrature branch imbalances, and jitter-induced distortions. Using this model, an integrated analysis of combined channel mismatch effects is provided. Given error parameters or their distributions, closed-form expressions of the expected output signal-to-noise ratio and image rejection ratio are formulated for FI-ADCs with an arbitrary number of channels. The inherent circuit behaviors, sampling clock jitters, and local oscillator phase noise effects are also discussed. Based on the analysis and modeling, a discrete-time equivalent model for FI-ADC systems is derived. Therefrom, an integrated channel mismatch compensation scheme is proposed that contrasts existing signal recovery approaches which calibrate specific types of errors separately. The performance of this novel method is compared with conventional solutions using extensive simulations. Very favorable numerical results are observed.

Analysis and Design Specifications for Full-Duplex Radio Transceivers Under RF Oscillator Phase Noise With Arbitrary Spectral Shape

In this paper, the effects of oscillator phase noise (PN) with arbitrary spectral characteristics on the self-interference (SI) cancelation capability of a full-duplex radio (FDR) transceiver are addressed, and design considerations for optimized phase-locked loop (PLL) design in FDR are given. This paper first presents a full-duplex transceiver model that inherently mitigates most of the phase-noise effects from the SI signal. The remaining effect of the PN is then analyzed, and closed-form expressions for the SI power are derived. In the simulations part, a practical PLL-type oscillator is used, which is based on the arbitrary mask phase-noise model. Analytical derivations are verified with the simulations, and the SI cancelation performance is thoroughly studied with various parameters. Design considerations are finally given for oscillator design in FDR transceivers, with the help of tangible parameters of the PLL-type oscillators.

Analysis of Oscillator Phase-Noise Effects on Self-Interference Cancellation in Full-Duplex OFDM Radio Transceivers

This paper addresses the analysis of oscillator phase-noise effects on the self-interference cancellation capability of full-duplex direct-conversion radio transceivers. Closed-form solutions are derived for the power of the residual self-interference stemming from phase noise in two alternative cases of having either independent oscillators or the same oscillator at the transmitter and receiver chains of the full-duplex transceiver. The results show that phase noise has a severe effect on self-interference cancellation in both of the considered cases, and that by using the common oscillator in upconversion and downconversion results in clearly lower residual self-interference levels. The results also show that it is in general vital to use high quality oscillators in full-duplex transceivers, or have some means for phase noise estimation and mitigation in order to suppress its effects. One of the main findings is that in practical scenarios the subcarrier-wise phase-noise spread of the multipath components of the self-interference channel causes most of the residual phase-noise effect when high amounts of self-interference cancellation is desired.

Accurate Characterization of Oscillator Phase-Noise Corrupted OFDMA-Uplink

This paper focuses on the analysis of the effect of oscillator phase-noise on OFDMA waveforms. First, general uplink OFDMA signal model is described with transmitter and receiver phase noises. Then, the signal-to-interference+noise ratio is analysed in phase noise corrupted OFDMA link. The analysis is based on accurate statistical analysis of the phase noise process, and it is carried out for arbitrary subcarrier mapping and channel frequency response. The results are then verified with simulator.

Uplink Performance of Time-Reversal MRC in Massive MIMO Systems Subject to Phase Noise

Multiuser multiple-input-multiple-output (MIMO) cellular systems with an excess of base station (BS) antennas (Massive MIMO) offer unprecedented multiplexing gains and radiated energy efficiency. Oscillator phase noise is introduced in the transmitter and receiver radio frequency chains and severely degrades the performance of communication systems. We study the effect of oscillator phase noise in frequency-selective Massive MIMO systems with imperfect channel state information. In particular, we consider two distinct operation modes, namely, when the phase noise processes at the M BS antennas are identical (synchronous operation) and when they are independent (nonsynchronous operation) . We analyze a linear and low-complexity time-reversal maximum-ratio combining reception strategy. For both operation modes, we derive a lower bound on the sum-capacity, and we compare their performance. Based on the derived achievable sum-rates, we show that with the proposed receive processing, an O(√M) array gain is achievable. Due to the phase noise drift, the estimated effective channel becomes progressively outdated. Therefore, phase noise effectively limits the length of the interval used for data transmission and the number of scheduled users. The derived achievable rates provide insights into the optimum choice of the data interval length and the number of scheduled users.

PLL Tracking Performance in the Presence of Oscillator Phase Noise

The tracking performance of a Phase Lock Loop (PLL) is affected by the influence of several error sources. In addition to thermal noise and dynamic stress error, oscillator phase noise can cause significant phase jitter which degrades the tracking performance. Oscillator phase noise is usually caused by two different effects: Allan deviation phase noise is caused by frequency instabilities of the receiver's reference oscillator and the satellite's frequency standard. It can be termed as system-inherent phase noise and is relevant for both static and dynamic applications. “External” phase noise, however, is caused by vibration and is a major problem for dynamic applications. In the context of this paper, both types of phase noise will be modeled and the resulting integrals will be evaluated for PLLs up to the third order. Besides, phase jitter induced by thermal noise and signal dynamics will also be discussed, thus providing all necessary formulas for analyzing the performance of a phase lock loop in case of different forms of stress. Since the main focus is centered on the effects of oscillator phase noise, the overall PLL performance is graphically illustrated with and without consideration of oscillator phase noise. © 2002 Wiley Periodicals, Inc.

The effect of phase noise on noncoherent digital communications

The effect of oscillator phase noise on noncoherent data detection is considered with the objective of relating more specifically than in prior studies the phase noise key parameters (bandwidth, spectral slopes, upper and lower cutoffs, spectral height). The concentration is on binary frequency-shift keying (FSK) and differential phase-shift keying (DPSK). Expressions that relate decoding error probability to the phase noise spectra are derived. It is shown that decoding degradation can be accurately approximated by relatively simple integrals involving the phase noise structure function (the latter obtained directly from the phase spectrum). Examples with reported crystal and cesium oscillator noise are presented. The key phase noise parameters are the spectral bandwidth relative to the bit rate, and the gain level of the phase noise (the latter being dependent on the carrier frequency to which the oscillator is multiplied). Separate results are derived for FSK and DPSK, but the order of the degradation is comparable in both cases. >

K-Band Tracking System for Domestic Satellite Communication System

System design and operational results of a tracking system for a K-band Earth station antenna with a diameter of 11.5 m are discussed. Monopulse tracking technique using higher order waveguide modes is utilized. An investigation was conducted to clarify the rainfall effect and the effect of oscillator phase noise on the tracking receiver. An autotrack system is to be manufactured on the basis of these studies. Experiments were performed using the medium capacity communications satellite. No cross coupling was seen in the pull-in patterns. Sufficiently good results were obtained in tracking accuracy: less than 0.005° (peak value) under normal conditions, and less than 0.01° under an average wind velocity of more than 20 m/s.