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Optimal Design of APSK Constellation & Study of Its Modulation and Demodulation

Author: LiuZhiXin
Tutor: LeiZuo
School: National University of Defense Science and Technology
Course: Information and Communication Engineering
Keywords: APSK Channel capacity Minimum Euclidean distance Pre-distortion compensation Nonlinear equalization Nonlinear distortion Soft demodulation
CLC: V423.41
Type: Master's thesis
Year: 2007
Downloads: 289
Quote: 2
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Abstract


Satellite communications has many unique advantages over other transmission media , but with the development of broadband satellite communications , the useful spectrum resources are increasingly limited , one of the solution is to improve the spectrum utilization , choose the higher order modulation signals satellite communications. Traditional high spectral efficiency QAM on the satellite channel the HPA nonlinearity is not suitable in transmission. Higher order modulation scheme to switch to the APSK, so close to the the MPSK constellation of power efficiency , but also with the rectangle QAM as having a high spectral efficiency . We study the purpose of of APSK this constellation for low signal-to-noise ratio , and non-linear characteristics of the satellite channel , from the largest minimum Euclidean distance and the mutual information of the two largest aspects APSK optimize the selection of the optimal matching relative radius and relative phase. HPA nonlinearity on the signal serious nonlinear distortion , a number of compensatory measures to be taken . This paper comparisons on the the APSK constellation of pre- distortion compensation by HPA , ideal APSK signal restored after by HPA , this program is better than the other programs , and nonlinear equalization combined with the receiving end , achieved very good effect. APSK are higher-order modulation QAM constellation , there are similarities in the modem program . This paper involved APSK modulation and demodulation draws on some of the methods of QAM . Satellite Channel low SNR superior error correction coding , should be used to compensate , when necessary, using other simple modulation scheme combining APSK modulation , such as DVB-S2, the synchronization header portion π / 2 BPSK modulation scheme . For APSK is circular , a coding method different from the QAM characteristics , the paper also proposes a soft - demodulation method for APSK constellations .

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CLC: > Aviation, aerospace > Aerospace ( Astronauts ) > Rocket, the spacecraft structure (overall ) > Spacecraft design and construction of > Satellite > Overall design
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