Diversity design in wireless communications

Diversity is a technique used for improving performance in sensing and wireless communications. Although diversity has been around for well over seventy years, and has been adopted in almost all wireless links over the last decades, the design of efficient diversity systems is still not widely understood. Typically, design is from coarse rules-of-thumb adapted from the literature - some results being purely experimental, others purely from simplistic models. The design adaptation is often without analysis of the specific link situation at hand. We present a tutorial-style look at the design for diversity, with an instructive example of frequency diversity for communications. It is shown, using a new parameter, how the application-specific fundamental design choices depend on the characteristics of the transmitting antenna, the receiving antenna, the multipath link characteristics, and the propagation environment. Without accounting for these factors together, the design is likely to have room for improvement. New research is identified that would be useful for diversity design.