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Magnitude Modulation for Peak Power Control of RRC Pulsed-Shaped Signals

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

Magnitude Modulation for Peak Power Control of RRC Pulsed-Shaped Signals, Proc Conf. on Telecommunications - ConfTele, Santa Maria da Feira, Portugal, Vol. -, pp. 209 - 212, May, 2009.

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The peak power control of root-raised cosine (RRC) pulsed-shaped signals has always been a concern in radio transmission systems in order to maximize the efficiency of the transmitter’s high power amplifier (HPA). The problem is emphasised when RRC with very low roll-off are used, as for the use of high-order constellations, due to the increase on the peak-to-average power ratio (PAPR) of the signal to transmit. Magnitude Modulation (MM) is a technique proposed with success for reducing PAR of QPSK transmission. This paper shows that it is possible to use the MM concept for constellations with M>4. In order to reduce look up table computation complexity and storage requirements, the constellation and RRC symmetries are explored. The method’s capability to avoid phase modulation is also improved. Experimental results show considerable gains of 70%-80% in back-off reduction for 16 QAM and 16-APSK constellations.