Optimization of 16-APSK modulation for SC-FDMA transmission system

Single Carrier Frequency Division Multiplexing (SC-FDMA) scheme has been considered to be promising technology for the uplink of the 4G mobile communication systems. The main disadvantage of SC-FDMA is high envelope fluctuation of signal resulting in a presence of nonlinear distortion in transmitted signal due to the transmitter high power amplifier (HPA). In order to improve the SC-FDMA performance, the 16-ary Amplitude Phase Shift Keying (16-APSK) is proposed as a base-band modulation scheme for SC-FDMA instead of conventional M-QAM. The different types of 16-APSK modulations will be investigated and positions of constellation points will be optimized according to maximizing Minimum Euclid Distance (MED) criterium. The performance properties of different 16-APSK and 16-QAM based SC-FDMA transmission scheme will be illustrated using numerical results. The obtained results will show that optimalized M-APSK modulation in SC-FDMA transmitted system provide better performance than 16-QAM SC-FDMA system or unoptimalized 16-APSK SC-FDMA system if the nonlinear operation of HPA has to be assumed.