I am an ELECTRONICS final year student and I am working on a project, "Full Duplex Radio On a Single Frequency". So is it possible to design such a project. If so then give me the idea about it, how can i design such a circuit, what do i need for it (mircrontroller, raspberry pi etc)? I have some idea about it but i don't know how to implement it.
If you have a single frequency with a single antenna, the best you can do is half duplex on the RF side -- you can't transmit and receive at the same time on the same frequency. If you have two antennas sufficiently separated (on both ends), you might be able to use signal diversity and geometry to separate signals; this would work better on higher frequencies (>5GHz?)
However, an easier way to do this would be to do timed half duplex (the two ends take turns transmitting), and digitize, compress, and packetize audio so that the audio is full duplex, even though the RF is only half duplex. TDMA?
Until the last 20 or so years, this would have been extremely difficult to accomplish in the analog domain. With advances in processing power applied to DSP however, Spatial Multiplexing is a reality -- that is, the ability to send different signals on the same channel simultaneously. It is done by having separate, and multiple TX/RX radio chains -- each carrying different information -- separated by some distance causing different "paths" through reflection, refraction, etc of each link... processing is able to distinguish one stream of data from another through characterizing each path-channel, yet they occupy the same frequency. It is not entirely an intuitive concept. Lots of math.
Most of us have already experienced something similar (though not exactly the same) with MIMO (multiple in multiple out) technology that came with the 802.11n standard for WiFi. Those routers you may have with multiple antennas (like 4, or 6, or 8....) are using a form of MIMO. This significantly increases channel capacity, and hence throughput on a single frequency -- so you can happily watch Netflix on your laptop.
Here is an example of a project done by Stanford on employing this technique on Full Duplex / Same channel. Its a bit of a slog to read, but you're a student -- so you might actually like it :)
Also, here is a brief tutorial on MIMO -- implemented for WiFi -- discussing some of the basics around spatial multiplexing. Cool stuff.