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22nd April 2014 at 05:55 #69593profGuest
I am fairly new to 3G. I am using NEMO outdoors for DT. It gives Ec/N0 of each cell in the monitored set. Now Ec/N0 is something like C/I in GSM which is only applicable in dedicated mode.
How is it measuring Ec/N0 of cells that UE is not in dedicated connection with.22nd April 2014 at 06:34 #69594profGuest
Well. I think I got my answer. C/I does not correspond to Ec/N0; it corresponds to DTCH BLER instead; which again can only be calculated once the UE has dedicated channels assigned to it.
Ec/N0 is simply a ratio of powers at a very “low level” (i guess physical layer). No data has been received and checked for errors yet.
Do correct me if I am wrong.22nd April 2014 at 09:26 #69595pixGuest
well, i assocaite C/I with Ec/No, because, roughly speaking, you do average your useful signal over the noise, in both case.
EcNo can easily be measured in Idle mode, and is actually a replacement for how RxLev is used in 2G. EcNo is really the most common measurement in 3G, and is used to know whether a cell is good or bad (much more so than the RSCP)
Each cell sends some pilot signals which can be decoded and compared against the global noise. I don’t know the exact names of those channels, but that shouldn’t be too hard to find out.
pix22nd April 2014 at 09:45 #69596profGuest
Thank you pix. Your answer helped. Also, I found this on Ascom’s website:
“It is possible to measure C/I in both idle and dedicated mode. In idle mode, you will get a C/I value on the BCCH carrier in the serving cell.”
So, my initial assumption that C/I in GSM is only measured for dedicated mode was wrong (although that is what I deduced from observing TEMS logs).
I am throwing whatever I got at you guys so that I may stand corrected at the end. This is a great forum.