Ka-band propagation measurements: an opportunity with the Advanced Communications Technology Satellite (ACTS)

Bauer, Robert A.

doi:10.1109/5.598409

Cited by 30 publications

(16 citation statements)

References 8 publications

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“…It is well known that rain attenuation of radio wave is significant in satellite communications using frequencies of higher than 10 GHz such as Ku band (14/12 GHz) and Ka band (30/20 GHz) (e.g., Arbesser-Rastburg and Brussaard 1993, Dintelmann et al 1993, Bauer 1997, Karasawa and Maekawa 1997. Rain attenuation may become very severe even for Ku-band radio waves in heavy rain regions like the tropics (Pan et al 2001, Pan andAllnutt 2004).…”

Section: Introductionmentioning

confidence: 99%

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

Maekawa

Fujiwara

Shibagaki

et al. 2006

Journal of the Meteorological Society of Japan

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This study investigates the effects of tropical rainfall on the Ku-band satellite communications links that connect Research Institute for Sustainable Humanosphere (RISH), Kyoto University in Japan to Equatorial Atmosphere Radar Observatory (EAR; 0.2 S, 100.3 E) in Indonesia, using the satellite Superbird C (144 E in orbit). Rain attenuation of the up-and down-link radio wave signals is, for the first time, obtained at the same time in the tropics, monitoring each signal level that has been received at both stations in Japan and Indonesia for the past three years from 2003 to 2005. The up-link attenuation at each station can be estimated from the down-link signal level measured at its opposite station, because SCPC (Single Channel Per Carrier) signals used in this experiment are linearly amplified without saturation of the satellite transponders. At EAR in Indonesia, a slightly larger attenuation ratio between up and down links is statistically presented for the attenuation range of higher that 10 dB, suggesting the effects of smaller raindrop size distributions (DSD) than observed at RISH in Japan. This tendency is more conspicuous in the rainfall events when the observed attenuation shows only one peak in its time series, indicating the effects of simple convective precipitating clouds with one single cell. At RISH in Japan, a larger difference between worst month and yearly average statistics is found, due to a larger variation of the ground temperature that affects the slant-path length during the seasons, although the yearly average time percentages as such are larger at EAR than RISH up to the up-link attenuation of 15 dB. Using time percentages of their local rainfall rates, fairly good agreement is found between the observations and the ITU-R (International Telecommunication Union-Radiocommunication Sector) predictions for both locations. At EAR in Indonesia, however, the time percentages of the attenuation of more than 10 dB become significantly smaller than those predicted by the ITU-R methods for both up and down links. This indicates the remarkable reduction of equivalent path lengths down to about 2 km, caused by a fairly localized structure of convective precipitating clouds. Simultaneous X band radar observations have revealed that intense echo cores of typical rain cells causing severe attenuation are confined to about 2 km along the propagation path. This result, which seems rather small even compared with those obtained in other tropical observation sites, may be attributed to unique features of the EAR site that is located in a highland basin 865 m above the mean sea level and frequently observes simple precipitating clouds with a single cell.

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Section: Introductionmentioning

confidence: 99%

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

Maekawa

Fujiwara

Shibagaki

et al. 2006

Journal of the Meteorological Society of Japan

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“…In other words, a possible method to provide a variable bandwidth channel to a link faded by rain is by resorting to a spare channel (a shared resource) designed for this purpose. See [9] for the kind of information and detailed analysis necessary in a similar investigation and [5] for a practical use. This channel will be assigned dynamically and momentarily to the link, either downlink or uplink.…”

Section: Discussionmentioning

confidence: 99%

“…Now, we can define the average efficiency η, both for QPSK (2) and for Shannon capacity (5), as the ratio between the number of downloaded symbols and the number of downloadable symbols when A(t) = 0, both in T A . Because the latter is given by R o T A (or C o T A ), from (5) or (6), we obtain the following average efficiency:…”

Section: Equivalent Download Time During Rain Attenuation and Channelmentioning

confidence: 99%

“…In fact, if the size of the data volume downloaded in a given observation time T obs (a day, a week, a month, etc.) is more valuable than the instantaneous symbol or bit rate (as it may be the case in Earth resources observation or in other services that allow long delays in communicating data), another approach can be more useful and avoid overdesign, namely the various adaptive coding and modulation (ACM) techniques (in the vast literature on the subject, for brevity, see [1][2][3][4][5]). …”

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confidence: 99%

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A method to achieve clear-sky data-volume download in satellite links affected by tropospheric attenuation

Matricciani

2015

Int. J. Satell. Commun. Network.

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SUMMARYFor data downloading from satellites, the traditional approach of considering the complementary probability distribution, P(A trop ) of the total tropospheric attenuation A trop (dB), at a frequency, polarization, and elevation angle, may be too pessimistic, and it may lead to large overdesign. If the data volume downloaded in a given observation time T obs (a day, a week, a month, etc.), with a constant probability of symbol error, is more valuable than the instantaneous symbol, or bit rate (as it may be the case in Earth resources observation or in other services that allow long delays in communicating data), another approach can avoid overdesign, namely the various adaptive coding and modulation techniques. We study a particular time integral of A trop (t): (i) to define the average efficiency of a radio channel faded by the troposphere and (ii) to design a method that can theoretically achieve the same volume of data downloaded in clear-sky conditions (no troposphere), even if the radio link is faded by the troposphere. The average efficiency and its bounds can be calculated from the complementary probability distribution of A trop (t). We explicitly apply the theory to radio links faded by rain, by using the experimental rain-attenuation time series measured with satellite ITALSAT in a 37.8°slant path, at 18.7, 39.6, and 49.5 GHz at Spino d'Adda (Italy), and to those simulated with the synthetic storm technique. Based on the average efficiency, we define the method that can achieve in T obs , theoretically, the same data volume as in clear sky, directly applicable to quadrature phase-shift keying, multiple phase-shift keying, and Shannon capacity theorem. The method requires a fixed increase in power margin, and bandwidth, compared with clear-sky conditions, and delivers an average symbol rate equal to the maximum symbol rate obtainable when A trop (t) = 0. The method can also be used in terrestrial links at any frequency. We compare its theoretical performance with the traditional adaptive coding and modulation techniques and show that, even theoretically, these techniques cannot achieve unitary efficiency as, on the contrary, the novel method can do. Real-time satellite communications at frequencies above 10 GHz are characterized with the long-term probability distribution, P(A trop ), of total tropospheric attenuation A trop (dB) (a combination of attenuation due to rain, hail, snow, mist, water vapor, clouds, and oxygen), at a frequency, polarization, and elevation angle. This P(A trop ) refers to an average year, or to a shorter observation period, T obs , for example, a month, and is useful to calculate link budget and to assess link availability. The same approach holds for second-order statistics, such as fade duration and time derivative of fade (rate of change), which describe fading dynamics, especially with regard to rain attenuation, the most rapidly changing and less predictable tropospheric fade in slant paths. Fade duration statistics give information on the duration of continuous out...

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“…Rain attenuation is a function of frequency, elevation angle, polarization angle, rain intensity, rain drop size distribution and raindrop temperature. The communication link performance experiment included more than seven sites in North America and lasted for a period of five years [5]. Propagation factors that affect Ka band satellite links operating at moderate t o high elevation angles include: gaseous absorption, cloud attenuation, melting layer attenuation, rain attenuation and rain/ice depolarization.…”

Section: Ka Band Propagation Effects On the Communication Link Performentioning

confidence: 99%

Ka band system and propagation effects on system performance

Acosta

Johnson

2000

18th International Communications Satellite Systems Conference and Exhibit

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Abstract-The Advanced Communication Technology Satellite (ACTS) is an experimental communications satellite system launched in September 1993. ACTS introduces many new technologies, including operation in the Ka frequency band. ACTS uses multiple hopping narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for a bit-error-rates of 5x10 -7 or better over the continental United States. In order to maintain a minimum system availability of 99.5% over all US rain zones ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of system and sub-system characterization considering the statistical effects of system variances due to thermal and propagation effects over 6 years of ACTS operation including inclined orbit.

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Ka-band propagation measurements: an opportunity with the Advanced Communications Technology Satellite (ACTS)

Abstract: The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and

Cited by 30 publications

References 8 publications

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

A method to achieve clear-sky data-volume download in satellite links affected by tropospheric attenuation

Ka band system and propagation effects on system performance

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