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Reply To: GPRS

#51425
pix
Guest

DS,

The UL PDCH is not used by the MS, so the UL TBF is released. It cannot be “reused” for DL.

Look.. A ms in 4+1 will have a timeslot allocation that looks like this :

(note : the PDTCH is the logical channel used to carry Data on a PDCH)

DL PDCH allocation:
TS2=PDTCH
TS3=PDTCH
TS4=PDTCH+PACCH
TS5=PDTCH

UL PDCH allocation:


TS4=PDTCH+PACCH

when the UL PDCH is not used, the allocation will be :

DL PDCH allocation:
TS2=PDTCH
TS3=PDTCH
TS4=PDTCH+PACCH
TS5=PDTCH

UL PDCH allocation:


TS4=PACCH

However the MS will still send “Signalling” (not Data) on the UL PDCH, once in a while. This is the “UL PACCH”.

The second question : Yes, in UL, the MS will have to send RLC/MAC Acknowledgments. It is done through the UL PACCH.
Also it is probable that once in a while, after some DL download, the MS will have to send “higher protocol” acknowledgments (TCP Ack).

It is a little difficult to explain all this on a forum 🙂

Cheers,
pix