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Low Back-off 16-APSK Transmission Using Magnitude Modulation and Symbol Quantization

Gomes, M. ; Silva, V. ; Cercas, F. ; Tomlinson, M.

Low Back-off 16-APSK Transmission Using Magnitude Modulation and Symbol Quantization, Proc International Workshop on Satellite and Space Communications - IWSSC, Toulouse, France, Vol. *, pp. * - *, October, 2008.

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QAM and APSK are used to meet the ever growing demand for higher data rates in bandwidth limited satellite channels whose main constraint to communication capacity is a non-linear transmitting High Power Amplifier (HPA). The inherent APSK robustness against nonlinear distortion leads to its introduction in the recent standard for Digital Video Broadcasting (DVB-S2). Power efficiency is still limited by high signal PAPR at the HPA input. Magnitude Modulation is a technique for PAPR reduction, proposed with success for QPSK. This paper shows that it is possible to use the magnitude modulation concept for the 16-APSK case, even considering the huge number of symbol combinations. The method’s capability to avoid phase modulation is improved. In order to reduce look up table computation complexity and storage requirements, the constellation symbols are vector quantized. Constellation and RRC symmetries are also explored. Experimental results show considerable gains of 80% in back-off reduction.