Spectrum efficiency of multilevel modulation schemes in mobile radio communications

Lee (1989) has produced equations describing spectrum efficiency for modulation schemes operating in cellular environments. The present authors consider the performance of a range of multilevel modulation schemes when these spectrum efficiency equations are applied. They then proceed to adapt these efficiency equations for use in microcells before considering the performance of multilevel modulation within this environment. The results show that the preferred modulation scheme depends on the BER required, with 4 level PSK being preferred in conventional cells, and variable 16 level QAM, or 32 or 64 level QAM being suitable in microcells, particularly when a high SNR is available