It is usually considered that transmission and reception
can not be done simultaneously on the same antenna
on the same frequency. Normally the two directions
are multiplexed in frequency - which is known as frequency
division duplex (FDD) or in time - known as time division
duplex (TDD). Transmitting and receiving
on the same antenna at the same time is known a
single antenna full duplex (SAFD).
The fundamental problem with SAFD is that the transmitted
signal is significanly stronger than the received.
The transmitted signal will leak into the recceiver
even if a hardware component known as a circulator
ideally would suppress all of the signal.
The transmitted signal is often 100-150dB stronger than the
received. A system capable of SAFD will require
methods supress this interference by the same
number of dB before the signal is sent
to the demodulator. Only recently has this been achieved
(see reference 1 below).
Other uses of simultanous receive-transmit are relays and in radar.
In the project we will delop and implement point-to-point links
first using a channels made up by cables and attenuators and
then by transission over real hardware. First using an
intermediate-frequency set-up where transmission is performed
using cables and spliiters (arraned in a way that yields
significant self interference) and then using full radio chains.
However, since we do not have a circulator the system
will actually use different antennas for transmission and reception.
This will still be challange since the two antennas will be physically
close. In fact, it is so challenging that systems are not built that
way today.
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The basic requirement should be fulfilled with processing in Matlab and the USRP assignments done.