Low-complexity incremental use of multiple transmitters in wireless communication systems

In this paper we develop and analyze low-complexity approaches that we call incremental multiple-input multiple-output (IMIMO) for exploiting multiple antennas for reliable high-rate communications in wireless systems. The proposed schemes leverage consecutive uses of a single transmit antenna combined with automatic repeat request (ARQ) feedback, possibly with multiple receive antennas. Unlike multiple-input multiple-output (MIMO) communications without feedback, the schemes we propose allow for low-complexity transmitters and receivers because they do not require a space-time encoder or decoder. We compare the performance of IMIMO schemes with the corresponding MIMO system without feedback using outage probability as the metric for comparison. These comparisons show that for relatively low rates IMIMO schemes have better performance than the corresponding MIMO system without feedback. For higher rates, MIMO does better up to a certain signal-to-noise ratio (SNR), but beyond that threshold IMIMO schemes again have better performance.