An improved water-filling algorithm for mobile MIMO communication systems over time-varying fading channels

Multiple input multiple output (MIMO) systems that use antenna arrays at both the transmitter and receiver are gaining much more attention and efforts in wireless communication research due to their potential to increase considerably capacity in mobile cellular communications. However, in the real propagation environment of cellular communications, it is difficult to gain the ideal ergodic capacity for time-varying fading MIMO channels except using adaptive modulation and power water-filling in the space domain over every MIMO subchannel. A novel improved rate quantization (IRQ) algorithm is proposed using water-filling theory for power allocation and adaptive modulation. The simulation results show that, with low complexity, IRQ can obtain higher transmit power utilization and greater spectral efficiency than other present rate quantization and power allocation schemes.