Status of sysmocom/master W50

Andreas Eversberg andreas at eversberg.eu
Wed Dec 18 14:52:28 UTC 2013


Holger Hans Peter Freyther wrote:
> I am now going to re-write the allocation handling. In terms of operation
> on the first DL assignment (through the PCH) we can only use a singleslot
> but when re-using the TBF we might go for multislot. In case the of UL
> handling we could always try to use multislot assignments. Is this
> understanding correct?
hi holger,

when i designed multislot allocation algorithm, i considerd the following:

* for one-phase-access (UL), we don't know the multislot class, so i 
assume class 12, because it allows the maximum RX slots for semi-duplex 
operation. for two-phase-access we know the multislot class from the 
PACKET RESOURCE REQUEST. if the BTS provides 4 or more PDCH slots 
starting with TS1, the algorithm would select TS3 (iirc), because a 
later (concurrent) DL TBF with class 12 (or other classes) would allow 
to allocate TS1..TS4, so the phone can still transmit on TS3. the phone 
would schedule the following 8 bursts for one frame: "-tttt-r--" (t=TX, 
r=RX) if i would provide an UL TBF with TS1, the phone would be able to 
do the following scheduling only: "-tt-r---", so the algorithm can only 
assign TS1 and TS2 for RX. this means that the multislot algorithm must 
consider the RX slots when choosing a good TX slot, even with no ongoing 
DL TBF.

* similar to an allocated UL slot, the algorithm must choose the same 
slot for "control_ts", that is used for polling. even for DL TBF only, 
the control_ts slot must be allocated as if it would be an UL TS, 
because the phone must be able to answer, if it is polled. the 
control_ts and and an assigned UL slot may be the same TS.

* in case of first DL TBF assignment (phone is in packet idle mode), i 
use multislot algorithm too, because i know the multislot class from the 
LLC-DATA message. it is no problem to assign a single, but why do you 
want to assign a single slot here?

best regards,

andreas







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