- This topic has 21 replies, 1 voice, and was last updated 12 years, 1 month ago by KB.
30th June 2009 at 02:30 #57669KBGuest
How to improve data throughput?
Current cell parameter 4 Tre
-min pdch = 4
-max pdch = 22
-max high load = 4
voice traffic = ~ 40 – 50%
no.of Extra TS = 2
DL Throughput < 80 kbit/s30th June 2009 at 06:11 #57670PixGuest
what is your MAX MCS ?
what is your GPRS HIGH LOAD ?
how many cell in the BTS ?
What is MAX TBF PER SPDCH (UL & DL) ?
Why only 2 Extra timeslots ?
so regarding the current info:
max pdch highload is way too low (try to set it to 7 or 8)
extra ts is too low
waiting for your answers,
pix30th June 2009 at 07:31 #57671KBGuest
Thanks Master optimizer 😉
the problem occur all cell( ALU B9 )but sometime data thr > 180 kbit/s (static test)
MAX MCS = 9
GPRS HIGH LOAD = 80%
cell in the BTS = 3
MAX TBF PER SPDCH (UL & DL)= 5
MAX PDCH PER TBF = 5
Why only 2 Extra timeslots ? = no budget for 2 abis 🙁
could u pls recommend parameter setting and extra ts
KB30th June 2009 at 16:48 #57672krishGuest
hey pix can u explain this terms if u can ?30th June 2009 at 22:06 #57673PixGuest
KB, no problem 🙂
if you can’t work on your Abis capacity.. mmm…
BTS config = 4/4/4 ?
that’s (i assume) 3 BCCH + 6 SDCCH
so you have 9 bonus nibbles + 8 extra nibbles… that’s a total of 14 extra nibbles.
Imagine: one MS, with 4 PDCH at MCS-9. It will use 4 x 4.5 nibbles = 18 nibbles.
it will use its 4 basic nibbles + 12 extra nibbles.
All extra nibbles are used up by only one MS !!!
Since they are a lot of GPRS signallings (Attach, PDP context, RA update), many MS’s will require capacity… And therefore there won’t be enough even for the one MS that needs 4PDCH at MCS 9.
Conclusion: you must add extra TS. If you can’t, then the ONLY solution is to reduce TCH capacity. You can do it this way:
MAX PDCH HIGH LOAD = 5 … 7 … 8
GPRS HIGH LOAD = 85% … 90%
Start with values at the left, then try the values at the right. Check if you have improvements, step by step. Check your TCH congestion.
If your BTS is 4/4/4, you should have more than 2 extra abis nibbles left… I cant remember exactly, but it should be 5 or 6, no ?
Finally, check your GPRS indicators. You can see how much Abis nibbles are busy or free, how many PDCH are allocated in the cell, at busy hour, etc. They will really help you to understand what is limiting your TBF throughput.30th June 2009 at 22:09 #57674PixGuest
sorry… 18 nibbles = 4 basic nibbles + 14 extra nibbles !
your 2 abis ts are not enough to satisfy even one full-throughput MS.
The hi-speed throughput can only be achieved if there are only little amount of TCH allocated in the cell. (night ?)30th June 2009 at 22:13 #57675PixGuest
ooooch… i’m sorry, it’s really hard to explain it on a forum.
I can only tell you that the names of those parameters are quite self-explanatory. And unfortunately, if you don’t understand them, it means you need some fundamentals trainings about GPRS Alcatel. I’m not being arrogant (for once ?), because it’s really a difficult topic.
That’s why 3G is so successful. GPRS was too complicated to understand :))1st July 2009 at 03:16 #57676KBGuest
could u pls recommend no.of extra ts for 2 abis
KB1st July 2009 at 04:17 #57677KBGuest
If we got 2 abis,the current extra ts = 2 .Avg TRX/cell in urban = 5.could u pls recommend no.of extra ts for hi-speed throughput
Thank you in advance
KB1st July 2009 at 07:04 #57678PixGuest
extra timeslots are the timeslots which are not occupied by OML, RSL or TCH.
if those TS are not “extra” then they are nothing, they are lost. You might as well define them as extra, don’t you think?
if you have 2 Abis links, i think you can have much more than only 2 extra TS.
recommendation: this is a dimensioning job ! nobody is doing that in your company ?
ok, I recommend you to define 6 extra timeslots per BTS.
… what do you do with that number…? Please let me know.1st July 2009 at 16:32 #57679krishGuest
thanks for ur reply.
hey i want to understand only this term if u can
(1) dl edge and gprs thrput per tbf like value 75,200,121= it indicates data volume or speed?
(2) tbf success ratio per tbf= it indicates per ms ?1st July 2009 at 21:30 #57680pixGuest
(1) throughput is in kb/s the value you see is wrong
(2) i dont know this indic. check the formula.9th July 2009 at 02:11 #57681KBGuest
at here have team plan for low Throughput 😉
could u pls explain 4.5 nibbles at MCS99th July 2009 at 06:34 #57682PixGuest
not master, please…
one radio ts in Edge can carry up to 60kb/s, thanks to 8PSK modulation.
On Abis though, there is only 16kb/s per nibble, it can’t be enhanced.
So one PDCH (radio ts) is going to be carried over 4.5 Abis nibbles (GCH).
Pix18th August 2009 at 16:58 #57683AD BoyGuest
Hi guys, gone through this but I need to get more understanding. What if i have a case of 2cells i.e 4/4 Trx on cells 1 & 2. With (1BCCH + 2SDCCH) on Trx1 of Cell 1 and (1BCCH + 1SDCCH) on Trx1 of Cell2. How many Basic, Bonus and Extra Nibbles do I require? Also what are the total Number of Abis TS on [Basic, Bonus & Extra Nibbles]?