Phase noise effect on HIPERLAN/2 system performance

A design of a 5.6 GHz frequency synthesizer with switched bias LIT VCO and low noise on‐chip LDO regulator for 5G applications

In this study, we examined the effect of phase noise on the optical millimeter-wave (mm-wave) signal in a dense wavelength division multiplexing radio-over-fiber (DWDM-RoF) system. A single modulator was used to generate the optical mm-wave signal in the DWDM-RoF system. This paper addresses the impact of phase noise, which results from phase imbalance, on the optical mm-wave signal. To lower the effect of phase noise on the optical mm-wave signal, the phase imbalance should be controlled. The phase imbalance can be controlled and decreased by adjusting the phase at the phase shift (PS). The system performance was analyzed using various parameters such as bit error rate (BER), signal-to-noise ratio (SNR), optical signal to noise ratio (OSNR), and error vector magnitude (EVM). From the results, we found the phase imbalance affected the optical mm-wave signal due to the imbalanced splitting of the signal intensity at the MZM. The phase imbalance impacts the phase noise, which impacts the optical mm-wave signal. The phase noise could be decreased by controlling the phase imbalance at the phase of 5π/12. The best results at the phase of 5π/12 were collected for phase noise at 0.02 degrees.

This paper presents an in-depth analysis of effect of oscillator phase noise (PN) on the performance of orthogonal frequency division multiplexing (OFDM) systems in sub-terahertz (Sub-THz) band. We use the empirical PN measurement of current Sub-THz signal sources to propose a two-part PN model that captures the unique characteristics of PN in Sub-THz band. Subsequently, the proposed model is used to analyze the performance of OFDM systems affected by PN. Our analysis reveals some key distinctions between the effect of PN on the OFDM systems operating at Sub-THz and the same systems operating at conventional microwave frequency bands. In particular, we show that in these systems: 1) the PN floor has a significant effect on the performance degradation, 2) the assumption of PN being a low-pass process is inaccurate, and 3) the existing OFDM PN mitigation schemes are less effective. To verify our analysis the upper bound on the signal-to-interference-and-noise ratio (SINR) after using the existing PN mitigation schemes under limited computational complexity constraint is derived and the effect of PN floor on the SINR is analytically calculated.

<title>Abstract</title> The terahertz (THz) band has received much attention as a potentially usable bandwidth for 6G. Near-Earth THz is susceptible to strong atmospheric interference, and direct links are vulnerable to obstacles, limiting the breadth of its applications. Emerging intelligent reflecting surfaces (IRS) with multi-input multi-output (MIMO) techniques can mitigate the effects of signal interference and atmospheric turbulence through non-line-of-sight (NLOS) links. To address these challenges, this paper introduces IRS to enhance the coverage and system performance of THz links, and thoroughly analyses the performance metrics of the IRS-assisted THz communication system. First, the atmospheric perturbation of the MIMO THz system is modelled to analyse the characteristics of the perturbation. Given that the turbulence intensity in THz wave transmission is positively correlated with the distance, M\'alaga and Gamma-Gamma distributions are used to simulate the atmospheric turbulence channels from the transmitter to the IRS and from the IRS to the receiver, respectively. Subsequently, pointing errors are considered for the potential displacement deviation of the receiving aperture and the NLOS link. Based on this, the probability density function of the channel state for the NLOS link is derived, and the equal-gain combination (EGC) and maximum-ratio combination (MRC) reception schemes are examined. The numerical results indicate that appropriate modulation techniques can improve performance, while pointing errors and turbulence effects have a significant impact on performance. Increasing the number of input and output ports also significantly improves system performance for all receiving schemes. Comparative analysis reveals that the MRC scheme offers a higher gain compared to the EGC scheme, typically achieving a 1-5 dB performance gain. Still, this advantage diminishes as the number of input ports increases. Meanwhile, the effects of phase noise and phase shift on the system performance are analysed. As phase noise and phase shift continue to decrease, their impact on system performance will gradually diminish and approach zero. Consequently, the performance effects due to phase shift and phase noise are weaker compared to the differences in system performance caused by variations in system parameters.

In this paper, effect of phase noise on a CDMA-based satellite communication system is analyzed and simulated. The satellite broadcasting channel is modeled as combination of Rician fading and shadowed Rayleigh fading channels. The nonlinear Fokker-Planck method is employed to analyze the first-order PLL (phase locked loop) performance. Phase noise is modeled as a Tikhonov distribution. The performance is evaluated in terms of bit error probability. From simulation results, it is concluded that the phase noise substantially degrades system performance of a CDMA-based satellite system.

The time-varying nature of multipath channels in Orthogonal Frequency Division Multiplexing (OFDM) systems causes intercarrier interference (ICI) and complicates the channel estimation at the receiver. The introduction of the local oscillator phase noise further destroys the orthogonality between subcarriers, thus increasing the ICI contribution. In this paper, we investigate the combined effects of channel estimation errors and receiver oscillator phase noise. Furthermore, the common phase error (CPE) is also accounted for in the OFDM system. Using M-QAM modulation in Rayleigh fading channels, we also compare the system performance when the phase noise process assumes different distributions, and present analytical results for illustration, followed by simulation results for validation.

Quantitative assessment of effects of phase aberration and noise on high-frame-rate imaging

In this paper, the performance of OFDM systems is analyzed by introducing the lower and upper bounds of signal to interference plus noise ratio (SINR), when a system suffers from intercarrier interference (ICI) caused by phase noise whose linewidth is much less than the frequency spacing between subcarriers. The effects of system parameters, such as transmission data rate, number of sub-carriers and AWGN, are predicted by using the derived lower bound of SINR. We further derive the upper bound of the probability of symbol error based on different modulation schemes. It has been shown that the bounds are quite accurate and general for OFDM.

In this paper, we analyze the effects of oscillator phase noise and doubly-selective fading channel on the performance of the staggered multitone (SMT) system. Unlike the more familiar discrete multitone (DMT) systems, SMT is shown to be insensitive to self-interference effects due to phase noise. The impeding channel and phase noise interference coefficients are defined and theoretical expressions for the inter-carrier and intersymbol interference are derived to establish solid analytical basis. We demonstrate the resilience of SMT waveform to phase noise distortion and channel fading effects in numerical experiments using appropriate models and the theoretical considerations are shown to fit well with simulation findings. Our assessment indicates that SMT system performs nearly as well as the classical DMT modulation for non-dispersive channels, while it outperforms DMT system by 2 dB for the studied fading channel scenario and fixed equalization complexity for both systems.

In many radar and EW applications, after some processing, the envelope of the received pulse is calculated and is used for target detection. Most of the time only the effect of thermal noise is considered in such detectors, but in most of the practical applications, before envelope detection, the signal should be down converted from radio frequency (RF) to an intermediate frequency (IF). In this case, the phase noise of the local oscillator will affect the signal, too. Surprisingly, in contrast to thermal noise, the effect of phase noise on the envelope of signal becomes more considerable whenever the IF bandwidth is decreased. So there exists an optimum IF bandwidth for the receiver. In signals with higher bandwidths, thermal noise degrades the signal and in signals with lower bandwidths, the phase noise affects it. In this paper the optimum bandwidth is calculated under some realistic approximations. (4 pages)

In this article, a low phase noise signal source to be used as local oscillator in pulse Doppler radio frequency (PDRF) sensor is proposed. Innovative design techniques for realization of the low phase noise frequency source using phase-locked loop (PLL) and dielectric resonator (DR) are presented. Qualitative investigations have been carried out on the effect of phase noise in PDRF sensor performance. An X-band vibration resistant PLL-based frequency source with phase noise better than −95 dBc at 1 kHz frequency offset has been designed here. It also presents the design of a 7.6 GHz low phase noise, vibration resistant DR oscillator. Systematic analysis of the key design aspects, their thermal-vibrational stability, and ease of integration with hybrid microwave integrated circuits have been disclosed. A prototype board is fabricated, assembled in a compact mechanical enclosure of dimension 55 × 55 × 15 mm3. Finally, developed module is experimentally validated under 7.6 g rms magnitude random vibration test in three axes and compared results with other state of-the-art similar works. The comparison clearly shows the merit of present research work over other similar existing works.

Effects of Phase Aberration and Noise on Extended High Frame Rate Imaging

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In this paper, we investigate the phase noise properties and the impacts caused by phase noise on an OFDM system, we derive the approximate expressions for BER performance in AWGN channel with various modulations techniques. The performance degradation is analyzed by graphs of BER against the number of sub-carriers. Thus the choice of the number of sub-carriers involves a tradeoff between mitigation of multi-path delay spread and reducing phase noise effects. Simulation results also show that phase noise effects performance for BPSK, QPSK & 16 PSK constellation which lead to the conclusion that a phase noise mitigation mechanism is needed to obtain acceptable performance.

The effect of local oscillator (LO) phase noise of an ultra-wide band (UWB) receiver on the detection of a nearby WiMAX receiver is investigated. An expression for the spectrum broadening effect due to the phase noise is derived, and a practical method is presented to estimate the in-band interference due to the phase noise interaction with an interfering adjacent channel signal.