Binary and multilevel offset QAM, spectrum efficient modulation schemes for personal communications

Abstract

In personal communications, especially in small cells, high capacity is needed. The modulation scheme utilized must be spectrally efficient. The performance of linear binary and quaternary offset QAM schemes is simulated in indoor cellular environment. The performance and the spectrum efficiency is compared with GMSK, a constant envelope modulation scheme. Binary offset QAM is shown to be 10-35% more spectrum efficient. A comparison is made with conventional 4 QAM. Binary offset QAM is shown to be more robust against power amplifier nonlinearities. The spectrum efficiencies of binary and quaternary offset QAM schemes are compared. Offset QAM schemes are shown to be good candidates for the third-generation mobile radio system.<>