Abstract
The technology of using massive transmit-antennas to enable ultra-reliable
single-shot transmission (URSST) is challenged by the transmitter-side channel
knowledge (i.e., CSIT) imperfection. When the imperfectness mainly comes from
the channel time-variation, the outage probability of the matched filter (MF)
transmitter beamforming is investigated based on the first-order Markov model
of the aged CSIT. With a fixed transmit-power, the transmitter-side uncertainty
of the instantaneous signal-to-noise ratio (iSNR) is mathematically
characterized. In order to guarantee the outage probability for every single
shot, a transmit-power adaptation approach is proposed to satisfy a pessimistic
iSNR requirement, which is predicted using the Chernoff lower bound of the
beamforming gain. Our numerical results demonstrate a remarkable transmit-power
efficiency when comparing with power control approaches using other lower
bounds. In addition, a combinatorial approach of the MF beamforming and grouped
space-time block code (G-STBC) is proposed to further mitigate the detrimental
impact of the CSIT uncertainty. It is shown, through both theoretical analysis
and computer simulations, that the combinatorial approach can further improve
the transmit-power efficiency with a good tradeoff between the outage
probability and the latency.