Exact Performance Analysis of Joint Adaptive Modulation and Power Loading Transmission in Multi-Channel System

In this paper, we propose a hybrid adaptive modulation and power loading (AMPL) for wireless multi-channel system. While the hybrid adaptive modulation and diversity combining (AMDC) introduced in [1] exploits adaptive modulation and diversity combining scheme to achieve higher spectral efficiency, the proposed scheme in this paper jointly determines the transmit power and the constellation size of symbols for more efficient usage of channel resources, under the total transmit power constraint and the required bit error rate (BER). We derive exact closed-form expressions of the performance of the proposed scheme in terms of the spectral efficiency, the average BER and the outage probability. We also analyze the impact of imperfect channel estimation on the proposed scheme and validate our analytical results by simulations. Numerical results show that the hybrid AMPL offers higher spectral efficiency than conventional scheme, and is less sensitive to estimation errors than the hybrid AMDC as well.