GPRS

for 1 PDCH coded in MCS-9, there is a need of 4.5GCH

ie.
1 MS using 4PDCH in DL @ MCS9, it needs 4*4.5GCH = 18GCH

in UL, a MS can use more than 1 PDCH. It can use 2 PDCH without any special feature… (2+2 or 3+2)

There is also the new feature “extended dynamic allocation”, which allow the following configuration : 1+2, 1+3, 1+4, 1+5, 2+3, 2+4, 3+3

Anyway, the dimensioning of the GCH is always done in DL. When you got your result, for example the link needs “50 GCH”… then you design an ABIS link with 50GCH. There will be 50GCH in DL and 50GCH in UL. 1 GCH is always defined symetrically.

pix

the UL PDCH will be allocated on a TS where there is already one of the DL PDCHs (for this MS). If no UL PDCH is available (let’s say they are all fully used by other MS), then the DL PDCH will be reallocated somewhee else so that the UL PDCH can be established.

pix

hi pix,

Thats right.but i want to know that once i got pdch in ul and also i got dl pdch and i am surfing then after that ul pdch will release from that pdch ?

And if it release and during surfing i need ul pdch again then what will happen?

Hi Pix,

u said UL n DL TBFs are independent.

my ques was suppose an MS is using 4+1 PDTCHs. now in case of no UL data to be sent, will that 1 PDTCH be used in DL or can be used anywhere else.

also,during DL data tranfer going on, is some UL transactions(not data) take place simultaneously for a particular MS.

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

hi pix ,

Thanks .and ya i will be waiting for u on discussion abt thisnon edge?

u said that ul pdch is released if it is not used but ul pacch will continue upto dl tbf is continue is it right?

Now in erlc soft limit for tbf per pdch is 2 and hard limit is 32 per pset (in one pset may be 4 or more pdch) so every time when my dl tbf is continue then one ul pacch is occupied?
And pix have u tested persistent scheduling in egprs ?

Safar,

check out 3GPP TS 04.60

UL TBF release can be done with 2 dfferent mechanisms :

1/ without extended mode
UL TBF is released T_DELAYED_FINAL_PUAN (about 400ms) after last block has been uploaded.

2/ with extended mode
it is released T_MAX_EXTENDED_UL (about 2s) after last block is uploaded. This mode is done if activated in the BSS + if the MS supports it (Rel’4 MS onwards)

DL TBF is released after a “delayed” time defined by timer T_Delayed_DL_TBF_Rel (equals to T_NETWORK_RESPONSE_TIME = 1.6s in alcatel)

Best Regards,
pix