Over the last decades, the exponential growth of all types of wireless communication systems has had a profound impact on the world, both economically and socially. The seemingly insatisfiable demand for communication throughput is putting increasing strain on the naturally limited electromagnetic spectrum that is available to us. This challenge drives research toward innovative engineering solutions that maximize the efficient use of the spectrum in a variety of scenarios.

Lay summary

Nevertheless, toward that objective, one basic assumption has remained unchallenged over the years: a transceiver can only transmit or receive on the same frequency
band, but not both at the same time. Consequently, two communicating transceivers must share the spectrum, either in time (taking turns using
the whole spectrum) or in frequency (dividing the spectrum into two smaller sub-channels). This so-called half-duplex mode is used in the radio interface of
all wireless communication systems today.

In this project, we challenge that fundamental assumption and create full duplex transceivers, capable of simultaneously
transmitting and receiving on the same frequency band. The first obvious advantage is that the efficiency with which we use the spectrum is doubled.
Furthermore, even more significant improvements are possible, when considering a whole network of such full duplex transceivers. The famous hidden
terminal problem can be alleviated and the various techniques for relaying information become much simpler and much more efficient.

The principal difficulty that has made full duplex mode impractical so far is the strong self-interference. In this project we study, perfect, combine, and
finally implement various methods of self-interference suppression. We treat the entire problem from the ground up, first constructing theoretical models,
then adapting the suppression techniques to maximize their effectiveness, and finally building a comprehensive testbed. This will allow us to give the first
demonstration of full duplex operation in both narrow- and wideband channels, with single or multiple-antenna (MIMO) terminals, and in single link as well
as relaying scenarios.