- This topic has 12 replies, 1 voice, and was last updated 6 years, 7 months ago by chaman.
17th May 2010 at 13:14 #62742pratikGuest
I want to understand the significance of usflimit which is 2 in my nw and tfilimit?
If i will keeep it 0 or some other value 4 then what will happen?
Buddies i want to understand when it comes in picture and how works?17th May 2010 at 21:43 #62743SHELDONGuest
The USFLIMIT and TFILIMIT come into play if you have activated any feature that will keep a TBF alive for some time, even when there is no data to be transmitted.
A typical example of this is, extended UL TBF mode, whereby an UL TBF is kept alive even when the MS has finished sending its RLC blocks. In this case, the TBF is kept alive until the expiry of the timer ULDELAY. Keeping the TBF alive means that the TBF will reserve a USF and TFI. This is undesirable, because the reserved USF and TFI cannot be used to set up new TBFs which may even have data to transmit. (remember the USFs and TFIs are limited). In light of this, you specify a certain buffer of USFs (USFLIMIT) and TFIs (TFILIMIT), such that when the number of free USFs/TFIs are less than these limits, then active TBFs are released immediately they finish transmitting their data.
In your case (USFLIMIT=2), it means whenever the number of free USFs is less than 2, then any UL TBF will be released immediately after data transfer, ie, the TBF will not be kept alive.
If you set it to 0, then you can have more TBF setup failures, because you may run out of USFs. On the other hand, if you set it too high, you will have many early TBF releases, which is also undesirable.
I hope this makes sense to you.
SHELDON18th May 2010 at 03:31 #62744pratikGuest
Thanks buddy.ask to u one thing in normal case where this tfi and usf will come? And what is there exact role?
In normal tbf set up is it important?18th May 2010 at 13:05 #62745subhashGuest
i want to also understand this abt tfilimit and usflimit.plz explain i am new to this forum.19th May 2010 at 18:20 #62746pratikGuest
Plz help buddy20th May 2010 at 18:12 #62747pratikGuest
Buddyn waiting………..20th May 2010 at 21:39 #62748SHELDONGuest
A TFI is an identity used to distinguish TBFs.
Because we normally have many users in a PSET, each TBF is assigned an identity (TFI), so that any data that is transmitted on that TBF contains this identity. This helps the MS/BSS to determine which TBF the data belongs to.
A USF is a flag which is used to signal an MS to send. Once again because we multiplex PDCHs for many MSs, the BSS has to find a way to tell the MS when to transmit its data. This is done by assigning the MS a flag( USF) on each PDCH. Whenever an MS reads its USF in an RLC/MAC block, the MS can send its data in the next uplink radio block.
The TFI and USF are important for normal TBF setup. If there are no free TFIs or USFs on a PDCH (or PSET), then no additional TBF can be set up on the PDCH(or PSET).
Subhash, I already explained USFLIMIT and TFILIMIT in my first post23rd May 2010 at 12:35 #62749PRATIKGuest
buddy still have one confusionu said each tbf have tfi value buy if my tbf is divided into four pdch according to my class then for all that same tfi?
and also what abt there usf?
and finally in my some bscs some cells counter LDSTFI and bacause of that DL MULTISLOT ISBAD..So is it because of lack TFI values and in that BSCS TFILIMIT is 2 so should i increase this value?24th May 2010 at 16:08 #62750pratikGuest
Buddy can u help me to sort out this confussion?plz…….24th May 2010 at 20:36 #62751SHELDONGuest
Each TBF has one TFI. If you have 4PDCHs in a PSET, then any TBF which is setup on this PSET will be assigned one TFI. What this means is that, anytime one of the PDCHs has data which belongs to a particular PSET, it just inserts the TFI as part of the data and sends it.
I don’t have much info on LDSTFI. The only info I got on it says that it includes IP discards due to preemption. If that is the case, I don’t see how that would affect your DL MULTISLOT. And when you say your DL MULTISLOT is bad, what exactly do you mean? Is it low or high?
And by29th May 2010 at 14:51 #62752pratikGuest
thanks buddy.but for example if there are 4 pdch and i am getting for pdch according my multiclass capability of ms.
so here i am getting 4 pdch and my one tbf is on all that pdch .so question is for all 4 pdch i will get 4 tfi pr that one tbf i will get 1 tfi.?
and second is like if 4 pdch and all my 4 pdch are full with lots of tbf say per pdch8 user so 4 pdch* 8 = 32.ok but here we define tfilimit 2 then how all will get tfi?
and buddy u are right because of ldistfi no impact on dl multislot. thanks1st June 2010 at 12:11 #62753pratikGuest
buddy are u there?9th June 2014 at 11:51 #62754chamanGuest
Pl. help to reduce LDISOTH & LDISRR values to Improve TBF_SUCC_RATE in Ericsson System.