While studying information theory we do not consider any directionality of the channel.
There will be no change if Reciever and the Transmitter are interchanged (i.e. Lorentz Reciprocity is obeyed).
However, suppose if the channel is a non-reciprocal device like a isolator or a Faraday rotator, rather than a simple transmission cable. What are the consequences on the Information theory?
What would be consequences on Shannon Entropy and several theorems like Shannon-Coding theorem, Shannon-Hartley theorem etc. I have been googling with several terms like Non-reciprocal networks etc, but I have not been able to find anything. Any help will be appreciated.
Hi.,
A reciprocal network is a network by which the power losses are the same between any two ports regardless of direction of propagation (scattering parameter S21=S12, S13=S31, etc.
Examples of reciprocal networks include cables and standard transmission lines, attenuators, and the common passive power splitters and couplers. Two classic examples of non-reciprocal networks are RF amplifiers and isolators.
Dear Chetan,
welcome,
You touched an important point which is the channel reciprocity.
The Shannon channel capacity does not require reciprocity. It handels a communication medium which carry information signal from source to destination and namely it give the limit of the transmission speed in bits per second which is called the channel; capacity. So it handles the rate of data transmission in one direction. Such transmission mode is called simplex.
There is the half duplex which affect transmission in both directions but at different time slots. This is related to the physical ability of the channel.
So, reciprocity is an additional property of the channel independent of the channel capacity which is defined only in one direction.
There is also full duplex in this case one uses two channels one for the forward and one for the backward channels.
This is my opinion about the two properties. The channel capacity and the reciprocity.
Best wishes
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