Question regarding TS allocation algorithm(s)

Holger Hans Peter Freyther hfreyther at sysmocom.de
Mon Sep 30 16:01:05 UTC 2013


On Sun, Sep 29, 2013 at 11:05:05AM +0200, Holger Hans Peter Freyther wrote:
> On Sun, Sep 29, 2013 at 10:15:50AM +0200, Andreas Eversberg wrote:
> 
> > it is true tat algorithm A only assigns the first PDCH time slot. i
> > don't see any problems changing that by spreading TBF usage over all
> > available PDCHs.
> 
> okay. I am currently cleaning up the pcu (including the allocations
> algorithms), refactor and fix the subtle bugs that are due code
> duplication (e.g. like the one reported by Vladimir Rolbin). This
> also means that I will be busy and stall your osmo-bts changes
> until I am done with the clean-up here.

Okay, I started to read GSM 04.60 and the code. So right now we have
"global TFIs" so in each direction we can not allocate 32 TFIs right
now.

The spec says this:
"Each TBF is assigned a Temporary Flow Identity (TFI) by the network.
The mobile station shall assume that the TFI value is unique among
concurrent TBFs in the same direction (uplink or downlink) on all PDCHs
used for the TBF. The same TFI value may be used concurrently for TBFs
on other PDCHs in the same direction and for TBFs in the opposite
direction."

So if we combine the tfi/tbf allocation we could remove the current
limitation. I have some more ideas for cleanup after reading some more
of the code. I would propose to stick with C++ at this point in time
as information hiding (e.g. making certain parts of a struct private
can help with the structure of the code.)

holger



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- Holger Freyther <hfreyther at sysmocom.de>       http://www.sysmocom.de/
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