My research career began with trying to solve an open problem in designing robust high-capacity wireless networks: self-interference, an essential consequence of the broadcast properties of the wireless medium. The wireless medium is a shared resource, and thus if nearby devices (radios) transmit at the same time (and at the same or even neighboring frequencies), the transmitted signals collide, resulting in interference. In traditional network designs, interference is considered harmful, and consequently, networks have been architected around the conservative principle of avoiding interference whenever possible, which in turn limits the capacity of the wireless network.

It is generally not possible for radios to receive and transmit on the same frequency band because of the interference that results.’’ Wireless Communication, Andrea Goldsmith, 2005 [Chapter 7]