Joint Modulation and Beamforming for MIMO Systems with 1-bit DACs
Abstract
To realize multiple-input multiple-output (MIMO)
with low cost and power consumption, the use of low-resolution
digital-to-analog converters (DAC) is drawing significant interest.
While previous studies on massive MIMO systems with low resolution
DACs have focused on optimizing precoding, this
approach faces the limitation that the coarse resolution at the
transmitter makes it difficult to generate the transmit signal close
enough to the desired one when a small scale MIMO transmitter
is considered as in IoT networks. To address this problem, we
propose a new transmission framework that jointly performs
modulation and beamforming. With the proposed scheme, the
message symbol is directly mapped into a feasible transmit vector.
We also develop a channel-adaptive mapping function for the
proposed framework that minimizes error probability. Simulation
results show that the proposed scheme can improve the error
performance