Incremental Use of Multiple Transmitters for Low-Complexity Diversity Transmission in Wireless Systems

In this paper we develop and analyze low-complexity approaches called incremental multiple-input multiple-output (IMIMO) for exploiting multiple antennas for reliable wireless communications. The proposed schemes leverage consecutive uses of a single transmit antenna combined with automatic repeat request (ARQ) feedback. Unlike multiple-input multiple-output (MIMO) communications without feedback, the schemes we propose do not require a space-time encoder or decoder because they only use one transmit antenna at a time. We compare the performance of IMIMO schemes with the corresponding MIMO system without feedback using outage probability and average long-term throughput as metrics 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 with higher complexity performs better up to a certain signal-to-noise ratio, but beyond this threshold IMIMO schemes again have better performance.