MPM—An atmospheric millimeter-wave propagation model
01 Jun 1989-International Journal of Infrared and Millimeter Waves (ITS)-Vol. 10, Iss: 6, pp 631-650
TL;DR: In this paper, the authors characterized the neutral atmosphere for the frequency range from 1 to 300 GHz as a nonturbulent propagation medium and predicted attenuation and propagation delay effects from meteorological data sets: pressure, temperature, humidity, suspended particle concentration, and rain rate.
Abstract: The neutral atmosphere is characterized for the frequency range from 1 to 300 GHz as a nonturbulent propagation medium. Attenuation and propagation delay effects are predicted from meteorological data sets: pressure, temperature, humidity, suspended particle concentration, and rain rate. The physical data base of the propagation model consists of four terms: (a) resonance information for 30 water vapor and 48 oxygen absorption lines in the form of intensity coefficients and center frequency for each line; (b) a composite (oxygen, water vapor, and nitrogen) continuum spectrum; (c) a hydrosol attenuation term for haze, fog, ,and cloud conditions; and (d) a rain attenuation model. Oxygen lines extend into the mesosphere, where they behave in a complicated manner due to the Zeeman effect. The geomagnetic field strength H is required as an additional input parameter. Each 02 line splits proportionally with H into numerous, sub-lines, which are juxtaposed to form a Zeeman pattern spread over a megahertz scale. Patterns for three main polarization cases are calculated. Detailed examples for model atmospheres provide basic millimeter wave propagation information over the height range 0 to 100 km of the neutral atmosphere.
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TL;DR: This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.
Abstract: Communication at millimeter wave (mmWave) frequencies is defining a new era of wireless communication. The mmWave band offers higher bandwidth communication channels versus those presently used in commercial wireless systems. The applications of mmWave are immense: wireless local and personal area networks in the unlicensed band, 5G cellular systems, not to mention vehicular area networks, ad hoc networks, and wearables. Signal processing is critical for enabling the next generation of mmWave communication. Due to the use of large antenna arrays at the transmitter and receiver, combined with radio frequency and mixed signal power constraints, new multiple-input multiple-output (MIMO) communication signal processing techniques are needed. Because of the wide bandwidths, low complexity transceiver algorithms become important. There are opportunities to exploit techniques like compressed sensing for channel estimation and beamforming. This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.
2,380 citations
Cites background from "MPM—An atmospheric millimeter-wave ..."
...Alternatively, humidity and rain fades, common problems for long range mmWave backhaul links [60], 7 are not an issue in either short-range indoor links or micro-cellular systems [15], [61] with sub-km link distances....
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TL;DR: In this paper, experimental permittivity data of liquid water, compiled from the open literature, were selectively applied to support a modeling strategy, which was carried out by employing nonlinear least-squares fitting routines to data considered reliable.
Abstract: Experimental permittivity data of liquid water, compiled from the open literature, were selectively applied to support a modeling strategy. Frequencies up to 1 THz and atmospheric temperatures are covered with an expression made up by two relaxation (Debye) terms. The double-Debye model reduces to one term when the high frequency limit is set at 100 GHz, and the model can be extended to 30 THz by adding two resonance (Lorentzian) terms. The scheme was carried out by employing nonlinear least-squares fitting routines to data we considered reliable.
607 citations
TL;DR: The techniques and technologies currently being investigated to detect weapons and contraband concealed on persons under clothing are reviewed and the basic phenomenology of the atmosphere and materials that must be understood in order to realize such a system are discussed.
Abstract: The techniques and technologies currently being investigated to detect weapons and contraband concealed on persons under clothing are reviewed. The basic phenomenology of the atmosphere and materials that must be understood in order to realize such a system are discussed. The component issues and architectural designs needed to realize systems are outlined. Some conclusions with respect to further technology developments are presented.
575 citations
Cites methods from "MPM—An atmospheric millimeter-wave ..."
...2 were based on the AT model and used the same databases for the line structures but calibrated the attenuations and line shapes by contrasting them with MPM89 in the 500 GHz to 1 THz region....
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...The International Telecommunications Union (ITU) has accepted the work of Liebe [17] and Crane [20] as their standard method for calculating attenuation....
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...He points out that the temporal variation is due to the fine structure of atmospheric water vapor and its effect can be predicted with Liebe’s codes if the structure is known....
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...The region from 10 GHz to 1 THz was predicted using the ITU standards [23]–[25] which are primarily based on the MPM89 model developed by Liebe....
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...Significant work has been conducted since the original publication and has resulted in excellent physical models, such as MPM89 [17], AT [18], ATM [19], and the rain models of Crane [20]....
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TL;DR: In this article, a reanalysis of some of these measurements leads to the conclusion that the laboratory data are best represented by a combination of Liebe's [1987] millimeter-wave propagation model (MPM) for the foreignbroadened component of the water continuum and the 1993 version of MPM for the self-broadened components.
Abstract: Measurements, made in different laboratories, of absorption by water vapor in microwave windows are compared with models for the water vapor continuum. A reanalysis of some of these measurements leads to the conclusion that the laboratory data are best represented by a combination of Liebe's [1987] millimeter-wave propagation model (MPM) for the foreign-broadened component of the water continuum and the 1993 version of MPM for the self-broadened component. This combined model is validated by comparison with measurements of atmospheric microwave emission.
555 citations
TL;DR: In this paper, an improved version of this model was developed which requires ozone, in addition to temperature and water vapour, in the input profile and it has been generalized to compute radiances for other satellite radiometers using the same code.
Abstract: To assimilate atmospheric and surface radiance measurements from satellites in a numerical weather prediction model, a fast radiative transfer model is required to compute radiances from the model first guess fields at every observation point. Such a model for satellite infrared and microwave radiance measurements is used operationally for the assimilation of TIROS operational vertical sounder radiances at the European Centre for Medium-Range Weather Forecasts. An improved version of this model has been developed which requires ozone, in addition to temperature and water vapour, in the input profile and it has been generalized to compute radiances for other satellite radiometers using the same code. Instruments such as the high resolution infrared radiation sounder and the advanced microwave sounding unit on the National Oceanic and Atmospheric Administration polar orbiters, the METEOSAT water vapour imager and the Geostationary Operational Environmental Satellite infrared sounder have been simulated. It is demonstrated, by comparisons with line-by-line model computed radiances, that the fast model can reproduce the line-by-line model radiances for the TIROS operational vertical sounder stratospheric temperature sounding channels to an accuracy below the instrumental noise. The tropospheric, surface sensing, water vapour and ozone channel radiances cannot be predicted to such an accuracy, but still accurately enough for numerical weather prediction assimilation. A comparison of measured TIROS operational vertical sounder radiances with predicted values from numerical weather prediction model analyses gives larger differences than would be expected from the combination of the fast model and instrument related errors for most channels. The validity of the tangent linear approximation of the model gradient for typical radiance departures is also explored, with several examples, for the high resolution infrared radiation sounder/advanced microwave sounding unit instrument combination. The tangent-linear approximation is valid for temperature but significant departures from linearity about the first guess profile are observed for water vapour and ozone. Cloud affected infrared radiances have a highly non-linear response.
520 citations
References
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TL;DR: In this paper, the empirical relation A = aR^{b} between the specific attenuation A and the rain rate R is used in the calculation of rain attenuation statistics.
Abstract: Because of its simplicity, the empirical relation A = aR^{b} between the specific attenuation A and the rainrate R is often used in the calculation of rain attenuation statistics. Values for the frequency-dependent parameters a and b are available, however, for only a limited number of frequencies. Some of these values, furthermore, were obtained experimentally, and may contain errors due to limitations in the experimental techniques employed. The aR^{b} relation is shown to be an approximation to a more general relation, except in the low-frequency and optical limits. Because the approximation is a good one, however, a comprehensive and self-consistent set of values for a and b is presented in both tabular and graphical form for the frequency range f = 1-1000 GHz. These values were computed by applying logarithmic regression to Mie scattering calculations. The dropsize distributions of Laws and Parsons, Marshall and Palmer, and Joss et al., were employed to provide calculations applicable to "widespread" and "convective" rain. Empirical equations for some of the curves of a(f) and b(f) are presented for use in systems studies requiring calculations at many frequencies. Some comparison is also made with experimental results, and suggestions are given regarding application of the various calculations.
674 citations
TL;DR: In this article, a practical atmospheric millimeter-wave propagation model (MPM) is proposed to predict attenuation for dry air at 2.5-430 GHz. But the model is limited to frequencies below 300 GHz and the number of spectroscopic parameters can be reduced to less than 200.
Abstract: A practical atmospheric Millimeter-Wave Propagation Model (MPM) is formulated that predicts attenuation. delay, and noise properties of moist air for frequencies up to 1000 GHz. Input variables are height distributions (0-30 km) of pressure, temperature, humidity, and suspended droplet concentration along an anticipated radio path. Spectroscopic data consist of more than 450 parameters describing local O2 and H2O absorption lines complemented by continuum spectra for dry air, water vapor, and hydrosols. For a model (MPM*) limited to frequencies below 300 GHz, the number of spectroscopic parameters can be reduced to less than 200. Recent laboratory measurements by us at 138 GHz of absolute attenuation rates for simulated air with water vapor pressures up to saturation allow the formulation of an improved, though empirical water vapor continuum. Model predictions are compared with selected (2.5-430 GHz) data from both laboratory and field experiments. In general, good agreement is obtained.
515 citations
01 Sep 1983
TL;DR: In this paper, the authors review the theories and results of numerical calculations of interactions between hydrometeors and microwaves or millimeter waves propagating in media containing these hydrometers.
Abstract: This paper reviews the theories and the results of numerical calculations of interactions between hydrometeors and microwaves or millimeter waves propagating in media containing these hydrometeors. At frequencies above about 5 GHz, rain, snow, or ice crystals in high altitudes cause various degrading effects on the performance of communication links. The attenuation of the transmitted signals is a well-known example of such effects. Because of the demand for more communication channels, operating frequencies of both terrestrial and earth--scace communication systems become increasingly higher, and the communication technology becomes more and more sophisticated with the use of digital techniques, or the use of both orthogonaly polarized channels. These have given rise to the need of acquiring more detailed knowledge of interactions between hydrometeors and waves than is necessary for the calculation of attenuation. To obtain such knowledge, we have to know the detailed microphysical properties of hydrometeors, such as shape, size distributions, or the motion of hydrometeors while they are falling. These properties, some obtained previously by meteorolgists and some obtaianed recently by radio engineers to meet the requirements of present radio problems, are reviewed first. Various methods of calculations, and the detailed knowledge obtained from calculations of the single scattering properties of hydrometeors, whose sizes are generally comparable to wavelength, are then reviewed. With the information of these scattering properties, various propagation phenomena are discussed from a theoretical point of view. Specific subjects treated include attenuation, cross polarization due to rain or ice crystals in high altitudes, the methods of depolarization cancellation, rain scattering other then forward and backward which is necessary in the estimation of rain scatter interference between two communication links operating at the same frequency, various multiple or incoherent scattering effects on copolar and cross-polar signals, pulse shape, channel transfer characteristics, etc. The aim of this review is to provide fundamental background informations on the interactions between hydrometeors and radio waves, and hence the more practical investigations, such as long-term statistics of attenuation, are beyond the scope of this review.
464 citations
TL;DR: In this paper, the propagation properties of suspended water and ice particles which make up atmospheric haze, fog, and clouds were examined for microwave and millimeter-wave frequencies, and the rates of attenuation alpha (dB/km) and delay tau (ps/km), derived from a complex refractivity based on the Rayleigh absorption approximation of Mie's scattering theory, were derived.
Abstract: Propagation properties of suspended water and ice particles which make up atmospheric haze, fog, and clouds were examined for microwave and millimeter-wave frequencies. Rates of attenuation alpha (dB/km) and delay tau (ps/km) are derived from a complex refractivity based on the Rayleigh absorption approximation of Mie's scattering theory. Key variables are particle mass content and permittivity, which depends on frequency and temperature both for liquid and ice states. Water droplet attenuation can be estimated within a restricted (10+or-10 degrees C) temperature range using a simple two-coefficient approximation. Experimental data on signal loss and phase delay caused by fog at four frequencies (50, 82, 141, and 246 GHz) over a 0.81-km line-of-sight path were found to be consistent with the model. >
171 citations
TL;DR: In this article, the interference coefficients were determined for the 5-mm wavelength oxygen lines broadened by air and solved by the Twomey-Tikhonov method, which minimizes a cost function, subject to the condition of constant measurement error variance.
Abstract: Interference coefficients describe the non-Lorentzian effect that arises as pressure broadening causes lines to overlap. These coefficients, one for each line, are at moderate pressures related linearly to absorption and dispersion. They are determined here for the 5-mm wavelength oxygen lines broadened by air. The method includes four a priori constraints on off-diagonal elements of the relaxation matrix, which produce the interference effect: (1) detailed balance; (2) intra-branch submatrices are assumed to be identical; (3) coupling between the + and - branches is ignored; (4) coupling between the (positive-frequency) resonances and the nonresonant and negative-resonant branches is represented by a small bias term in the interference coefficients. The linear equations relating measured dispersion to the interference coefficients are solved by the Twomey-Tikhonov method, which minimizes a cost function, subject to the condition of constant measurement-error variance. The cost function is chosen to minimize the variation of elements along diagonals of the intra-branch relaxation submatrix. Implications for atmospheric radiative transfer are briefly discussed.
99 citations