# how to determine a length of a channel? ( given path, delay)

Given a channel matrices for each subcarrier of a frequency selective channel (OFDM): i.i.d.. channel =(randn(ntx,nrx, N)+1i*randn(ntx,nrx, N))/sqrt(2); simulated via channel simulator and a number of paths, delay

With these parameters, Can I define a length of the channel or a number of clusters $$L$$?

With these parameters, Can I define a length of the channel

There's now $$n_{tx} \times n_{rx}$$ (or, depending on how you consider the this, $$n_{rx}$$), with potentially different lengths, not just one channel!

The only thing that makes sense to define as "the channel length" is the maximum length among these many channels.

However:

The fact that you're using a working OFDM already says someone else has found the length of maximum length of the channel, and used that as length of the cyclic prefix.

So, really, nothing to do here. If there was anything to do, your OFDM would either be inefficient (too much CP) or wouldn't work (too short CP).

• As I understood you, the length of CP is a length of the channel, isn't? I am confused now... – user36610 May 28 at 16:42
• exactly, and since you've already got a working system that does a CP, you can just look at the system. – Marcus Müller May 28 at 17:17