Space-Time-Frequency Domain Water-Filling in MIMO-OFDM Fading System

In this paper, we have derived the form of the maximum capacity for MIMO-OFDM system by adaptively allocating power in space, time and frequency domains in the case of perfect channel side information at the receiver (CSIR) and a zero-mean spatially white (ZMSW) channel distribution at the transmitter. Both the effects of Rayleigh fast fading and shadowing on the ergodic capacity are considered. The ergodic capacities achieved by the three different power allocation schemes, filling water in space-time-frequency domain, filling water in space-frequency domain and equally allocating power, are compared. For the ergodic capacity, the optimal power allocation scheme is filling water in space-time-frequency domain, which can obtain the maximal capacity as well as reduce the computation complexity.