Radio communications: components, systems, and networks [Series Editorial]

During radio system development, a great deal of attention is paid to new techniques that have emerged in communication science: on increasing bandwidth, operating range, and spectrum utilization; and on creating high-performance hardware and software architectures that are energy efficient, have low weight, and are secure. Developing efficient and effective mobile devices, however, demands more than just new coding methods or pushing channel utilization ever closer to the Shannon limit. For example, such devices need to coexist not just with other devices, but also with the human beings who use them. How are we to increase the number of transmitter chains in a multiple-input multiple-output (MIMO) device without running afoul of exposure limits? RF testing is another often overlooked issue. MIMO devices require a complex RF propagation environment to function properly: multipath is our friend! But the consequence is that modern devices contain lots of permanently integrated antennas that are essential components of the RF chain. How can these devices be adequately tested?