Normally shared frequency analogue1 radios (CB, aviation, etc.) can't receive when transmitting, because the signal being transmitted is much louder and will jam any signal from different transmitter.
Is it possible to somehow subtract the transmitted signal to be able to pick out signals from other transmitters even when transmitting? Is there any published design that allows receiving while transmitting or at least detecting that there is another transmission in progress?
1 Or digital, but with short packets collisions are less disruptive and there are other ways around the problem like slot allocation.