Evaluation and Measurement of the Doppler Spectrum in a Reverberation Chamber

Chen, Xiaoming

doi:10.2528/pierm12091808

Cited by 7 publications

(15 citation statements)

References 20 publications

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“…To justify the uncorrelated scattering (US) model, the instantaneous propagation is modeled as a continuum of uncorrelated point scatterers. This approach is consistent with our previous findings [2], and also work undertaken by Chen [7] in a reverberation chamber. Concerning the wide-sense stationary (WSS) model, it seems reasonable that the correlation of two measurements is only dependent on the time interval between them.…”

supporting

confidence: 90%

“…Heddebaut et al have also addressed this issue by investigating the ratio of stirred energy to unstirred energy (which they define as the stirring ratio) for an in-vehicle channel, with measured values in the range 12-20 dB [15]. While to our knowledge there are no existing measurements of Doppler spreads in vehicles, there are results of Doppler spreads measured in reverberation chambers [7], [12], [16]- [19]. Of particular interest are the Doppler spreads presented in [12], where measurements were performed with the stirrer moving (i.e., equivalent to our variation cause 2), and also with a single antenna moving (i.e., equivalent to our variation …”

Section: A Causes Of Channel Variation With Timementioning

confidence: 92%

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Characterizing the Spectral Properties and Time Variation of the In-Vehicle Wireless Communication Channel

Herbert

Wassell

Loh

et al. 2014

IEEE Trans. Commun.

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To deploy effective communication systems in vehicle cavities, it is critical to understand the time variation of the invehicle channel. Initially, rapid channel variation is addressed, which is characterized in the frequency domain as a Doppler spread. It is then shown that, for typical Doppler spreads, the in-vehicle channel is underspread, and therefore, the information capacity approaches the capacity achieved with perfect receiver channel state information in the infinite bandwidth limit. Measurements are performed for a number of channel variation scenarios (e.g., absorptive motion, reflective motion, one antenna moving, and both antennas moving) at a number of carrier frequencies and for a number of cavity loading scenarios. It is found that the Doppler spread increases with carrier frequency; however, the type of channel variation and loading appear to have little effect. Channel variation over a longer time period is also measured to characterize the slower channel variation. Channel variation is a function of the cavity occupant motion, which is difficult to model theoretically; therefore, an empirical model for the slow channel variation is proposed, which leads to an improved estimate of the channel state.

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supporting

confidence: 90%

Section: A Causes Of Channel Variation With Timementioning

confidence: 92%

Characterizing the Spectral Properties and Time Variation of the In-Vehicle Wireless Communication Channel

Herbert

Wassell

Loh

et al. 2014

IEEE Trans. Commun.

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“…The micro Doppler phenomenon can be researched by the dynamic measurement of a micro motion target in the AC [8]. When the Doppler effect is produced by several mode-stirrers in the RC [9], an inverted Vor Bell-shaped Doppler spectra can be obtained, and characterized by specific threshold power [10]. By utilizing a slowly moving mode-stirrer, the heavy Doppler effect can be emulated and analyzed by sampling method [11].…”

Section: Introductionmentioning

confidence: 99%

Doppler Spread Spectrum of a Circularly Moving Receiver in an Anechoic and a Reverberation Chamber

Jeong¹,

Park²,

Choi³

et al. 2014

PIER C

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“…A question now arises as to whether such a medium can generate Doppler‐like frequency shifts when source and observer are at rest. Such a question is particularly interesting for reverberation chambers, as there is evidence of Doppler shift broadening caused by tuned‐step mode stirring [ Chen , ; Karlsson et al , ; Hallbjörner and Rydberg , ; Tichy and Baade , , ]. In the past, this question has been answered in the context of correlation‐induced frequency shifts in optical sciences [ Wolf et al , ].…”

Section: Generalized Frequency Shiftmentioning

confidence: 99%

“…It is expected that the eigenfrequencies in an RC are subject to Doppler‐like shifts. As a matter of fact, several investigators have recently focused on the Doppler spread of signals in RCs [e.g., Chen , ; Karlsson et al , ; Hallbjörner and Rydberg , ; Tichy and Baade , ].…”

Section: Introductionmentioning

confidence: 99%

Transient evolution of eigenmodes in dynamic cavities and time-varying media

Gradoni

Arnaut

2015

Radio Sci.

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In this paper, we investigate the perturbation of natural eigenmodes of dynamic cavities with boundaries moving at quasi-static speeds relative to the wave velocity. For an arbitrarily shaped source-free cavity, the amplitude of the irrotational mode is modeled as a damped harmonic oscillator with time-varying eigenfrequency, i.e., a parametric oscillator. It is found that the effect of the pure Doppler shift of the resonance frequencies of the eigenmodes is small at nonrelativistic speeds. However, it is known that any spectrum of eigenenergies that is perturbed by a space-and/or time-fluctuating medium can develop frequency shifts of arbitrary magnitude. By using a linear dynamic (time-dependent) shift for the cavity broad resonances, we find that Doppler-like large shifts result in a mere frequency modulation of the total (resultant) field amplitude, while nonuniform red or blue shift can create a hybrid amplitude and frequency modulation. Interestingly, the combined action of red and blue shifts of uniform magnitude can also create a hybrid modulation. If the angle between modal wave vector and stirrer speed is accounted for in the static (time-independent) shift, the resulting red and blue shifts lead to irregular hybrid modulations. This can occur even for regular perturbations in regular cavities. In addition, owing to the stochastic nature of mode-stirred cavities, the effect of random Doppler-like shifts is also investigated, leading to a Fokker-Planck equation whose diffusion coefficient shows quadratic dependence on the mode amplitude. Thus, the analysis of random perturbations offers an effective framework for observed instantaneous Doppler effects in closed electromagnetic environments. The mathematical framework obtained in terms of stochastic differential equations is useful to predict the nonstationary response of dynamic cavities with complicated or unknown boundary geometry.

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Evaluation and Measurement of the Doppler Spectrum in a Reverberation Chamber

Cited by 7 publications

References 20 publications

Characterizing the Spectral Properties and Time Variation of the In-Vehicle Wireless Communication Channel

Characterizing the Spectral Properties and Time Variation of the In-Vehicle Wireless Communication Channel

Doppler Spread Spectrum of a Circularly Moving Receiver in an Anechoic and a Reverberation Chamber

Transient evolution of eigenmodes in dynamic cavities and time-varying media

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