The New Full Duplex
- James Nolan for edn.com September 11th, 2012
- Source: http://www.edn.com/electronics-blogs/waveforms/4395919/-The-New-Full-Duplex
Recently, over a period of a handful of weeks there were several announcements regarding full duplex as a next technology. There was this announcement from University of Waterloo, as well as some work by NYU-Poly professor Mike Knox and his team that's part of our collaboration with the university and which was announced and covered by EETimes, among others.
Full duplex is nothing new; most cellular systems today are actually full duplex in that your handset is transmitting and receiving at the same time. But the sticking point is that it is transmitting in one frequency channel and receiving in another frequency channel that's separated quite a bit in frequency. That duplex spacing is what lets your handset transmit and receive at the same time, as well what makes it practical to build a radio that uses relatively inexpensive filters to prevent the transmit signal from leaking into the receiver and completely obscuring the incoming signal.
So, when we talk about the new, full duplex technology, the driver is to be able to transmit and receive on the same frequency. It doesn't take much thinking to realize that this would double the spectral efficiency of the system.