Feature #1530

Assign same TFI number in downlink/uplink

Added by zecke over 2 years ago. Updated 6 months ago.

Target version:
Start date:
Due date:
% Done:


Estimated time:
Spec Reference:


        // 12-22-2011: It looked like the Blackberry abandoned an uplink TBF when
        // a downlink TBF was established using the same TFI.   This seems like a horrible
        // bug in the MS, but to work around it, I added the gFixTFIBug which uses
        // a single TFI space for both uplink and downlink.  This eliminated
        // a bunch of msStop calls with cause T3101, so I think this is a genuine
        // problem with MSs and we need this fix in permanently.
        // Update: The TFI is reserved during the time after a downlink ends, so the MS
        // may have been justifiably upset about seeing it reissued for an uplink too soon.

The above is from the OpenBTS code and we should assume this to be a valid issue. In general Jolly's code can also end-up in the situation where DL/UL think they have a common control_ts but in fact they are different. One way to resolve this would be to create a "MS" structure that holds IMSI, TLLI, TFI a pointer to the UL TBF and one to the DL (we don't support multiple TBF anyway). This way we could make sure the reservation is done in the right way.


#1 Updated by zecke over 2 years ago

From Jacob:

This might have been related to the old/new TBF handling in those days. Today the MS object keeps track of all active TBF (there can be more than 2 at a time sometimes) and the TFI of all of them are blocked until a timeout expires or a TBF is replaced by another of the same direction.
Thus an too early reuse of a TFI shouldn't happen.

Downlink and uplink TFI are managed independently and is is possible that both directions get the same value. But I haven't observed any problems of this kind with the E71 and the iphone.

#2 Updated by laforge 6 months ago

  • Assignee deleted (msuraev)

Also available in: Atom PDF

Add picture from clipboard (Maximum size: 48.8 MB)