The Research Of Broadband Satellite Communication System Channel Estimation At Ka-band

With the continuous development of the field of wireless communications, thegrowing demand for broadband multimedia services, the existing spectrum resourcescannot meet the demand for communication services, which makes the development andapplication of the Ka-band to become a research focus at home and abroad. TheKa-band frequency range is approximately20-30GHz, a wider frequency band, whichmeans less interference and larger capacity, is commonly used in satellitecommunications systems. However, Ka band has an obvious disadvantage is that therain attenuation is more serious, and would seriously affect the transmissionperformance of the satellite communication system. For the systems of broadbandsatellite communication, the channel has a frequency-selective fading characteristic; thesignal has different fading degree at different frequencies. With these factors, it isdifficult to accurately estimate the channel characteristics. Therefore, the study ofKa-band with serious rain attenuation and broadband communication system channelestimation techniques has a certain value and practical significance.Based on the above introduction, this thesis consists of five chapters, main researchwork is the second chapter, the third chapter and the fourth chapter, and overview ofeach chapter is given below.Chapter one is the introduction of the whole thesis, firstly, it introduces thecharacteristics of the Ka-band broadband satellite system, the research background, andthe development at home and abroad, as well as research significance, and finally itintroduces the main contents of this thesis as well as chapters arrangements.Chapter two introduces the Ka-band rain attenuation characteristics firstly, thenanalyzes the dynamic rain attenuation time series synthesis process based on rainattenuation prediction model recommended by ITU wireless sector (ITU-R) andsimulates the rainfall sequence of a certain area, finally, analyzes several anti-rainattenuation measures. The uplink power control algorithm is also studied in this chapter.As wideband channel has a feature of frequency selective fading, chapter threeselects muti-carrier OFDM system. The channel state has a direct impact on thecommunication quality, and therefore, the accurate channel estimation has important significance. This chapter is based on the massive pilot, firstly introduces severalcommonly channel estimation algorithms and performs simulation, then, in view of theRice channel, based on the two-dimensional rectangular pilot module, carries out anin-depth study of the Wiener filter estimation algorithm, according to the simulationresults we know that Wiener filtering algorithm achieves better performance thanexisting interpolation algorithm.Chapter four introduces adaptive technology against rain attenuation. SNRestimation is an important part of the adaptive coding and modulation techniques,therefore, accurate estimation of channel parameters is necessary in order to achievemaximum throughput based on muti-carrier OFDM system. For Rice channel, severalcommonly used SNR parameter estimation algorithms are introduced, and the existingalgorithms was modified, according to the simulation diagram we know that theimproved algorithm has better performance than the original one.Chapter five gives the summary of the full thesis, and points out the future researchdirections.