Proposal of a Power Efficient $N$-Level Multipulse PPM-$L$QAM Technique

A new power efficient technique, that combines N-level multipulse pulse-position modulation with L-level quadrature-amplitude modulation, denoted by NMPPM-LQAM, is proposed. Its constrained power efficiency is derived and characterized. It is shown that the proposed combination provides a superior technique that is both power and spectral efficient simultaneously. The constrained power efficiencies of variations to this technique are considered and characterized as well. These include combining multilevel pulse-amplitude modulation with LQAM (NPAM-LQAM). The obtained constrained power efficiencies are compared numerically to that of traditional LQAM and MPPM-LQAM techniques. Our results disclose that proposed NMPPM-LQAM is the most power/spectral efficient technique. For example, at spectral efficiency constraints of 2.5 and 4.2 bs-1/Hz/pol, the corresponding constrained power efficiencies of proposed NMPPM-LQAM technique are higher by about 4.87 and 3.62 dB, respectively, than that of traditional LQAM. In addition, the results reveal that NPAM-LQAM scheme has increased power and spectral efficiencies compared to that of traditional NPAM, but its power efficiency is less than that of traditional LQAM.