Wireless networks often struggle to run in full duplex because the access points (AP) have a hard time listening when they are transmitting.
An AP would send and then have to say “over” before getting a response that it could hear — like a hand-held radio. Researchers now say that the AP can avoid this problem by adapting to its own transmission noise, canceling it out, so it hears only signal(s) even though it is still transmitting.
It is like wearing headphones that cancel noise and are specifically tuned to eliminate your own voice:
This paper presents Antenna Cancellation, a novel technique for self-interference cancellation. In conjunction with existing RF interference cancellation and digital baseband interference cancellation, antenna cancellation achieves the amount of self-interference cancellation required for full-duplex operation.
This could double the performance of an AP. The authors also explain why doubling the number of physical devices, which also may achieve the same objective, is less compelling:
…a wireless full-duplex system that can nearly double the throughput of a single hop link is practically implementable. On the other hand, the implementation uses additional resources that could otherwise be used to implement a 2×2 MIMO system, that may provide similar physical layer gains. It is unclear if only the physical layer gains of full-duplex would justify the engineering and cost needed to implement these systems. However, we believe that the true beneï¬t of the full-duplex system lies beyond this gain in the physical layer. Practical full-duplexing can mitigate many of the problems with wireless networks today. Full-duplexing helps address three distinct challenges in current wireless systems: hidden terminals, congestion due to MAC scheduling, and high end-to-end delays in multihop wireless networks. Further, full duplex can have applications to future wireless networks that use cognitive radios.