MIMO delay-limited communications

An important problem for delay-limited communications requires to minimize the required transmit power for ensuring an acceptable outage probability for a given number of blocks transmission. In this paper, we consider a multiple-input multiple-output (MIMO) Rayleigh block flat-fading channel and investigate the joint optimization of power allocation and MIMO vector coding exploiting causal channel state information at the transmitter (CSIT). Using an upper bound outage probability, we derive the suboptimal power allocation and MIMO vector coding solution in closed-form, and we show that the suboptimal solution has a water-filling interpretation among the MIMO channel at present and some statistics of the future channels.