Hybrid M-QAM with Adaptive Modulation and Selection Combining in MIMO Systems

In this paper, we propose a hybrid M -ary Quadrature Amplitude Modulation (M -QAM) transmission scheme that jointly uses adaptive modulation and selection combining for singular value decomposition (SVD)-based multiple-input multiple-output (MIMO) systems (AMSC-MIMO). We derive exact closed-form expressions of the performance of the proposed scheme in terms of the average spectral efficiency and the outage probability. Numerical results show that the proposed hybrid M -QAM scheme offers higher spectral efficiency and lower outage probability than the conventional adaptive modulation in MIMO systems.