Re: Transmitting on a single subcarrier

[Marcus Müller]

Hi Sourya,

On 16.03.24 22:30, Sourya Saha wrote:
> I am using an OFDM transmitter and receiver blocks from GNU radio. Essentially what i want 
> to do is split up the bandwidth into 64 subcarriers and trasmit on any one of the 
> subcarriers, say subcarrier 3.

Remark: that is just FSK, but due to the nature of OFDM an FSK with a less-than-pretty 
symbol shaping, and due to the cyclic prefix, an FSK with a phase jump within each symbol.

*Usually*, you'd avoid doing that, and just build an FSK system. Especially, since if you 
only use one carrier at a time, you lose the ability to sense the channel, or use 
Schmidl&Cox (or similar methods) for synchronization, so there's no arguments going for 
OFDM here – that's why I pointed out that OFDM was a rather advanced topic, you need to 
understand *why* you're using it, fighting *which* channel problems.
You get all the complexity, the overhead and all the problems of OFDM, without any data 
rate benefit.

However, nothing in GNU Radio would stop you from doing that:
Data vectors with a lot of zero entries and a single non-zero entry.

> If that is to be done, in the data carriers field of the  ofdm transmitter and 
> receiver, mentioning just '3' as the subcarrier should work.

Not sure what "mentioning" means, but as described above: data vector with all zeros, but 
a non-zero value in the third entry.


Best,
Marcus