Diversity-Multiplexing Trade-Off in Continuous Aperture Array (CAPA)-Based Fading Channels

The diversity and multiplexing performance of continuous aperture array (CAPA)-based multiple-input multiple-output (MIMO) channels is analyzed. Angular-domain fading models are derived, and an angular-domain transmission framework is proposed to support CAPA-based MIMO communications. Asymptotic expressions are derived for the achievable outage probability (OP) and average data rate (ADR), and insights into the diversity-multiplexing trade-off (DMT) and associated array gain are provided. Further, the performance of CAPAs is compared with that of conventional spatially discrete arrays (SPDAs) to highlight the advantages of CAPAs. Analytical and numerical results demonstrate that: i) CAPAs achieve lower OP and higher ADR than SPDAs; ii) CAPAs attain the same DMT as SPDAs with half-wavelength antenna spacing but with a higher array gain; and iii) CAPAs outperform SPDAs in DMT when the antenna spacing exceeds half a wavelength.