Analysis Of Rain Attenuation And Counter Measures For Ka Band Satellite Communication

With the development of satellite communication transmission frequency to Ka band, atmospheric effects in the process of signal transmission is more and more serious, especially the rain attenuation, which will be up to tens of decibels. Theoretically, to ensure link availability, the rain margin is a good choice. However, the actual consumption will be great. Moreover, it is only in small part time that the margin is needed, during the most of the time it will be idle, which brings about the waste of system resources considerably.Access to a large number of ITU-R Recommendations published in recent years, the thesis sorts out the new rain attenuation factor calculation model, using Microsoft Visual Studio 2005 as the platform, the MFC dialog based interface, by the C++ programming language. In our country the latitude 25 degrees, east longitude 110 ° to 120 ° region as an example, the proposed rain attenuation model and China’s 1998 release of rainfall were compared and analyzed. The simulation shows that in the same transmission link availability, the new system based the proposed rain attenuation model can prevent up to 10 dB rainfall preparation margin waste. The simulation software of rain attenuation is designed, which will provide tools and basis for the rainfall margin design in the subsequent various orbit communication satellite altitude or remote sensing satellite system.Because the signal attenuation of Ka band is greatly influenced by rainfall and other factors in the process of transmission, needs to change strategy according to the size of real-time transmission attenuation. In the link availability conditions, in order to make the signal efficient transmission, avoid leaving a lot of rain margin and bring the system resource waste problem, studied adaptive technology and DVB-S2 adaptive coding and modulation technique. Through analysis of 28 kinds of modulation and coding method in DVB-S2 standard, select 11 kinds can be used in adaptive coded modulation scheme in satellite communication system, it proposes coded modulation by adaptive margin under the condition of adequate rainfall, which provides a reference design for satellite communication system anti attenuation of rainfall.