Full duplex using single channel

[neazoi]

I was wondering if anyone has ever designed a full duplex wireless link using only one frequency (channel). It has to be digital of course and packet based I think.
Is there any such system?

 

[RFDave]

Full duplex implies transmitting and receiving at the same time. You can't do that using a single rf channel.

Dave
www.keystoneradio.com

 

[flatulent]

The above information is very true. You can almost get full duplex performance if the bit rate is very high and your TR and RT transition times are very short. This requires digitizing the signals going each direction and sending them much faster than the baseband information is received.

 

[neazoi]

I have thought so,
The whole proccess should be able to recover the oridinal data in almost real time so it should be very fast and packets and times should be kept small etc.
We are talking about using the same channel/frequency for both directions pretty much like a half duplex CB. But each speaker will occupy only a very tiny part of time (digital) so it would be "seen" as full duplex over the same frequency.

Is there any commercial circuit/network that does this?

 

[RFDave]

It's complicated to do in a system, because the system as a whole has to be synchronized so that one radio doesn't interfere with another radio. For example, if you are talking on such a radio, then your radio has to be synchronized with the one of your neighbor. If you are transmitting while he is receiving, your transmitted signal (At the same frequency) will interfere with his received signal.

I beleive WiMax will support a single band operation.

Dave

 

[neazoi]

Yes synchronization remains the main issue, like synchronization in computer networks. In fact it should be a network pretty much like the ones used by computers that is why is implemented in wimax as you said. So there is an area open for research there I suppose