Cellular Network Infrastructure » Radio Access Network » OsmoBTS

We now have a wiki page about timing advance: Timing_Advance

Yes, it's slow. But OTOH it can cope with at least 1 TA value every 2 second, so that's a MS moving at ~ 1000 km/h. The way it's implemented now, it's basically heavily dampened which means it should also be very stable.

An alternative is to make the step proportional to the toa difference, basically reducing the time to adapt.

Instead of doing +1 we'd do + (toa * alpha) alpha being the damped factor. The closer alpha is, the faster it's going to react but also the more it can oscillate in case of measurement noise.

Thoughts ? Is this really an issue ?

Yes, it's slow. But OTOH it can cope with at least 1 TA value every 2 second, so that's a MS moving at ~ 1000 km/h.

Hmm, you're right. GSM TS 05.10 says: "The control loop for the timing advance shall be implemented in such a way that it will cope with MSs moving at a speed up to 500 km/h", so the current implementation is compliant.

An alternative is to make the step proportional to the toa difference, basically reducing the time to adapt.
Thoughts ? Is this really an issue ?

Are there any other cases when the TA value rapidly changes and we need to react quickly?
If no, feel free to close this issue. Changing priority to low for now.

Ok, closing. Thank you Sylvain!