Erlang Forum Discussion for TBF Blocking

suresh - 4th July 2010 (08:50 GMT)

Hi,

i am new to huawei system and i worked on eric system.so can u help me to find parameters in huawei for voice like

half rate to full rate parameter,

full rate to half rate parameter,

intra cell handover parameter,

queuing,cls parameter

and in gprs

ondemand pdch parameter,

spdch

dynamic allocation

in uplink 4 timeslot

plz help.......

optimizer - 13th July 2010 (19:20 GMT)

hi suresh.

What software r u using for monitoring Um and Abis interface. How can i detect in huawei that bts internal alarms r not active(lets supose huawei want to hide them).


hi bijoy,

Buddy by hopwrboost u are telling my ho sucess improve at bsc boundries ok? BUt will it affect my tch drop because interference will increase ?

And buddy u are telling 32 pcu ?is it per bsc ?i mean like eric in one gddm we can put max 7 rpp and if its 100% utilized then i have to put another gddm.and in eric,nokia only one pcu in bsc so herein huawei can u plz explain?

Bijoy - 13th July 2010 (06:55 GMT)

Hi SureshHPB will definitely supress the poor radio environment.Also try increasing the Timers T3107 & T3121.

Like RPP in Er\\,in huawei we have GDPUP(PCU).Max PDCH(static+dynamic) per PCU =1024.Max cells per PCU =2048Max PDCH per BSC=8192.Max PCU Num=32.

Br\\Bijoy


Hi bijoy,

thanks buddy here i am facing the problem of poor ho sucess at bsc boundries within same msc everywhere in my network so by enabling handover power boost will help to improve ho sucess?

and one more thing buddy in eric for gprs harware side we are checking gddm capacity how many rps? so for huawei how to check and whats its capacity?


Sure ,there is.1.IntraCell AMR TCHH-TCHF Qual Ho Allowed2.IntraCell AMR TCHH-TCHF Ho Qual. Threshold3.IntraCell AMR TCHF-TCHH Ho Qual. Threshold4.IntraCell AMR TCHF-TCHH Qual Ho Allowed& there are also criteria like Pathloss,ATCB etc

Br\\Bijoy


Hi bijoy,

can we do half rate to full rate and full rate to half rate with quality threshhold like eric.


Hi SureshCheck out these parameters1.Level of Preempting Dynamic Channel2.Reservation Threshold of Dynamic Channel ConversionFor counters,check R93* counters

Thanks Pix.Hope you will arrange some water:-)(kidding dear)Br\\Bijoy


Hi bijoy,

thanks buddy great thanks a lot.

still want to know abt some parameter

here pdch reforming is for PS to CS.

but which parameter is for CS to PS. IF THERE IS PLZ TELL. because if i am defining dynamic pdch and there is more cs traffic then it will preempt my edge pdch.So plz tell this also if possible plz tell which are there counters.

Pix - 6th July 2010 (07:39 GMT)

Bijoy is back ! The forum is on fire this morning :-)


Hi Sureshhalf rate to full rate parameter-Ratio of TCHH(%)full rate to half rate parameter-TCH Traffic Busy Threshold(%)intra cell handover parameter-Intracell HO allowedqueuing-Allow EMLPPcls parameter-Load HO Allowedondemand pdch parameter-Maximum Ratio Threshold of PDCHs in a Cell(%)spdch-Huawei doesn't have SPDCH concept.dynamic allocation-PDCH reforminguplink 4 timeslot-Allocate Two Timeslots Switch for MS over Uplink.Till C12 version huwai supprts only 2 TSL in UL.


Hi bijoy,

Are u there i need ur help.


Hi buddy,

k thanks can u plz explain something abt power control huawei2 ? how it works?

and can u tell me something abr gb utilization ? how to check and how to calculate?

Bijoy - 23rd July 2010 (05:19 GMT)

Hi SureshFor improving HOSR,its better to stick to the basics,co-bsic-bcch removal,check for clock issue in BTS,etc etc.

Other than this,you can increase the "Max Resend Times of Phy.Info".

Regarding Huawei Power control Algorithm,its an enhanced power control algorithm which is based on Huawei Ⅱ powercontrol algorithm, alongwith exponential filtering, interpolation optimization, comprehensive decision, different thresholds and FH gain.

Please refer HED for more detailed description.

Do ask for any doubt.

Br\\Bijoy

suresh - 22nd July 2010 (12:26 GMT)

hi bijoy,

is there any other parameter thr which i can improve the hosr?

i tried ho boos tpower but i got the 50-50 percent result so plz tell if any new one?

and can u tell me something abt huawei 3 power control?


Hi SureshThe BTS will transmit at max power,& there will be no power control.

Br\\Bijoy

Frings - 16th July 2010 (01:53 GMT)

by switch on HBP function , the interference of the system will be slightly raised. but hopefully this can decrease the amount of handover failures and handover losts. so,the use of this function depend on how the increased interference will affect the network.

SURESH - 15th July 2010 (06:36 GMT)

Hi buddy ,

Thanks for reply but check my question i want to know without ho power boost how much power will be radiated by bts ? is it max or less?

and power control will come in picture?


Hi SureshWith HPB, the BTS transmit power is adjusted to the maximum before the BSC sends a handover command to the MS. In addition, the BTS transmit power is not adjusted during the handover to ensure the success of the handover.

When the receive level of an MS drops rapidly, a handover occurs. In this case, the BSC cannot adjust the transmit power of the MS and BTS in time. The MS may fail to receive the handover command, thus leading to the call drop.

Br\\Bijoy

SURESH - 14th July 2010 (10:29 GMT)

HI BIJOY

THANKS BUDDY I HAVE STILL ONE CONFUSION WITHOUT HO POWER BOOST HOW MUCH POWER IS RADIATED BY BTS? I THINK IT IS MAXIMUM OR SOMEWHAT LESS?


Hi SureshHPB will not impact TCH Drop.Rgarding PCU,this is what I know for BSC6000.

Regarding Nokia,max no. of logical PCU for BSCi was 8+1,higher versions have much more,say the latest flexi BSC have 60+10 logical PCU.

Mak - 19th August 2010 (13:12 GMT)

Anyone can send the SD Drop formula used by Huwaei.

suresh - 18th August 2010 (16:13 GMT)

Hey bijoy,

great man plz share if possible......


Hi,

bijoy where are u? buddy......


Hibijoy,

hey buddy i have discussed with one trainer he was telling that at a time pdch can handle total 9 tbf in ul + 7 in dl. but as with discussed with u and my knowledge it is at a time 16 in dl + 7 in ul is it k?

and he was explaining for this frame structure so if possible plz clarify?

and can u tell me how n3101,n3103,n3105 i means its significance?

and in huawei we have formula for tbf sucess is ul tbf attempts(for gprs+edge)+ dl tbf attempts (gprs+edge) / ul tbf success(for gprs+edge)+ dl tbf success (gprs+edge) .so is it ok because here after esblishing tbf if its drop then its not coming inn picture so can u help?

Bijoy - 11th August 2010 (08:09 GMT)

Hi Suresh1.You can cange each n every POC parameter.Its rather better to stick to the recomended values.

2.The DL PDCH can carry maximum 16 TBF's & the UL PDCH can carry maximum7 TBF's

3.RTT is measured as the time between request to request establish complete.

4.Yes,these parameters will help for sure.

Br\\Bijoy


Hi bijoy,

are u there?ur help require..........

ar-ef - 10th August 2010 (01:08 GMT)

is there anyone has a HUAWEI bts parameter dictionary..? i'm just starting to learn how to optimize a huawei bts..

thanks all


Hi bijoy,

great man thanks for information if i want to tune power control parameter of this huawei then which parameter i should go for?

and man i have one doubt about gprs,edge at a time how many tbf can continue? it is 16 (dl) + 7(ul) or out of 16 9 for dl+7 for ul?

and round trip time is calculated from its from (1)gprs attach request to gprs attach request establish or

(2) upto pdp context activation?

and last question if i want to inprove my uplink and downlink tbf sucess ratio then n3101,n3103,n3105 parameter will help? sorry for too many questions............

waiting..........

Amit Kumar - 29th July 2010 (11:01 GMT)

HI Dear,

I am new to HUWAEI system. In mY BSC TCH Completion is the main problem, please suggest what to do to improve TCH completion rate. Rest of KPI's are ok even HOSR is 98% in the BSC.


HiMy apologies for delayed response.

Huawei II Power control is based on MR compensation, prediction filtering and adjusting the power step based on the receive level/quality1. Power control based on the receive level

If UL/DL RX_LEV Upper Threshold < UL/DL receive level < UL/DL RX_LEV Lower Threshold, power control is not required. If the condition is not met, power control isrequired.If the receive level is less than UL/DL RX_LEV Lower Threshold, the power needsto be increased.Power increment = (upper threshold + lower threshold)/2 – receive level. If the valueexceeds the value of MAX Up Adj. PC Value by RX_LEV, take the value of MAX Up Adj. PC Value by RX_LEV instead.If the receive level is greater than UL/DL RX_LEV Upper Threshold, the power needsto be decreased.Power decrement = receive level – (upper threshold + lower threshold)/2.

2. Power control based on the receive qualityIf UL/DL Qual Upper Threshold < UL/DL receive quality < UL/DL Qual LowerThreshold, power control is not required. If the condition is not met, power control isrequired.If the receive quality is equal to or greater than UL/DL Qual Lower Threshold, thepower needs to be increased.Power increment = MAX Up Adj. PC Value by Qual.If the receive quality is less than UL/DL Qual.Upper Threshold, the power needs tobe decreased.Power decrement = MAX Down Adj. PC Value by Qual.

Deb - 8th September 2010 (13:13 GMT)

Hi Bijay,

Do you have any idea about timer T3195, T3191.

Regarding T3169 the value we can change in the system..1. Click on BSC60002.Press Alt+Ctrl+shift+F123. Right clink on BSC6000 & go to Config BSC attributes4. Go to inner software papameters.

It works..

BR// Debashis

Deb - 8th September 2010 (12:50 GMT)

SD Drop Formula in Huawei

([CM30:Call Drops on SDCCH]/[K3003:Successful SDCCH Seizures])*{100}

suresh - 8th September 2010 (11:43 GMT)

Hi bijoy,

buddy can u help?


Hi bijoy,

buddy sorry formula is reverse like ul tbf success(for gprs+edge)+ dl tbf success (gprs+edge)/ul tbf attempts(for gprs+edge)+ dl tbf attempts (gprs+edge) so is it ok or not?

and buddy can u tell me one thing like in ericsson gpraprio parameter which will decide dynamic pdch as a idle or busy like that in huawei which parameter is available?

Bijoy - 4th September 2010 (07:31 GMT)

Hi SureshIncreasing these timers will help for sure,but not much.Its better to tune other parameters like initial coding scheme,cleaner RF environment,UL & DL release delay,etc,etc....

Regarding TBF success rate formula,the formula you have mentioned is wrong,because how does attempts comes in numerator & success comes in denominator??Now,in case TBF establishment success rate,it shouldn't consider TBF drop,it will consider only blocking & MS no response.

Br\\Bijoy

suresh - 3rd September 2010 (11:42 GMT)

Hi bijoy ,

plz buddy help

suresh - 1st September 2010 (10:06 GMT)

Hi bijoy ,

thanks buddy so by increasing this N series counter will not help evena single point?

and foe formula whats ur sugeestion?


Suresh

The value of t3169 is 5 sec & it is hardcoded in Huawei,so you can't change it.

Increasing the MS No response related timers will not help much.

Regarding the formula,it is totally wrong!!!

SURESH - 25th August 2010 (15:36 GMT)

Hi bijoy,

buddy what is the value of t3169 and by if i have more reason for ms no response and if i increase this timer n3101,n3102,n3105 will help to improve tbf sucess?

and in huawei we have formula for tbf sucess is ul tbf attempts(for gprs+edge)+ dl tbf attempts (gprs+edge) / ul tbf success(for gprs+edge)+ dl tbf success (gprs+edge) .so is it ok because here after esblishing tbf if its drop then its not coming inn picture so can u help?


Hi SureshA PDCH can at a time support max 9 TBF in DL & 7 TBF in UL,But the theoritical max is 16 TBF in DL & 7 TBF in UL(but not at a time-remember).(As per Huawei---!!!!).As in Nokia & Ericsson,this is again 9 TBF(DL) & 7 TBF (UL).Regarding the TimersN31301:When the network after setting USF for a given TBF, receives a valid data block of this TBF fromthe mobile station in a block assigned for this USF, it will reset counter N3101,otherwise it is incremented by one.If N3101 = N3101max, the network shallstop the scheduling of RLC/MAC blocks from the mobile station for this USF and start timerT3169(T3169-Wait for Reuse of USF and TFI after the mobile station uplink assignment for this TBF is invalid).

N3103:N3103 is reset when transmitting the final PACKET UPLINK ACK/NACK message within a TBF(final ack indicator(FAI) set to 1). If the network does not receive the PACKET CONTROLACKNOWLEDGEMENT message in the scheduled block for this TBF, it shall increment counterN3103 and retransmit the PACKET UPLINK ACK/NACK message. If counter N3103 exceeds itslimit, the network shall start timer T3169.

N3105:

When the network after sending a RRBP field in the downlink RLC data block or in Iu mode alsoRLC/MAC control block, receives a valid RLC/MAC control message from the mobile station, itwill reset counter N3105. The network will increment counter N3105 for each allocated data blockfor which no RLC/MAC control message is received for this TBF.

Do ask for any doubt.

@bijoy - 20th September 2011 (06:41 GMT)

dear bijoy,am really concerned in optimising tbf drop rate, vendor is siemens, what parameters should i look at tuning to improve the kpi? any suggestion would help...

thanks in advance :)

Bijoy - 21st September 2010 (08:25 GMT)

Hi DebPlease explain what you need to know?

Br\\Bijoy

Deb - 21st September 2010 (06:51 GMT)

Hi Bijoy,

Have you experienced in DTM implememtations. We are planning implement this in our Network.

Pl. share your experience, if any.

BR// Deb


Thanks Suresh


Hi bijoy,

its not modified t3169 value in my nw

Hassan Daud - 17th September 2010 (12:18 GMT)

How can i troubleshoot crossed sectors


YesIt is the formula for TBF establishment success rate(100-TBF blocking).

The formula for TBF drop rate(100-TBF completion rate) will be different.

I asked you to check whether T3169 is modifible or not.

Br\\Bijoy


Hi bijoy,

thanks buddy but i think this formula looks like gprs/egprs establishment sucess rate is it?

because as per this formula after tbf establishment if tbf is drop then ther is no counter included here so am i right?can u share other formula?

and what u want to say by this i am not geeting it..Also,kindly check for T3169 like "Deb" said,if possible & let me know.

Aside Deb,thanks,nice info


SureshApologies for delayThe formulae seems OK.Pls check what counters are included in the success factor.

As per my knowledge,there is no such parameter in Huawei Like GPRSPRIO in Ericsson,but it may be there.

Also,kindly check for T3169 like "Deb" said,if possible & let me know.

Aside Deb,thanks,nice info

Br\\Bijoy


Hi bijoy,

buddy can u help?

Discussion About USF & TFI

pratik - 1st June 2010 (12:11 GMT)

Hi sheldon,

buddy are u there?

pratik - 29th May 2010 (14:51 GMT)

HI sheldon,

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. thanks

SHELDON - 24th May 2010 (20:36 GMT)

Hi Pratik,

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?

Regards,SHELDON

And by


hi sheldon,

Buddy can u help me to sort out this confussion?plz.......

PRATIK - 23rd May 2010 (12:35 GMT)

Hi sheldon,

thanks buddy.

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?


Hi Pratik,

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).

Regards,

SHELDON

PS:Subhash, I already explained USFLIMIT and TFILIMIT in my first post


hi sheldon,

Buddyn waiting...........


hi sheldon,safar,pix

Plz help buddy

subhash - 18th May 2010 (13:05 GMT)

Hi sheldon,

i want to also understand this abt tfilimit and usflimit.plz explain i am new to this forum.


hi sheldon,

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?


Hi Pratik,

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.

Regards,SHELDON


hi sheldon,safar,pix

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?

Other Discussion


Safar,

Once again, sorry for my delayed response.

When an MS is engaged in a downlink packet transfer, it's data is kept in a buffer (or queue) on the PCU. Now if the MS reselects another cell, it sends a cell update message to the SGSN. When the SGSN notices that the mobile was already engaged in packet transfer, the SGSN sends a FLUSH message to the PCU of the old cell. The contents of this message can result in one of the following:1. If the new cell belongs to the same RA as the old cell, then the PCU moves the contents of the buffer to a new buffer for the MS, and the counter FLUMOVE is incremented.2. However, if the new cell is in a different RA, then the PCU discards the contents of the buffer, and FLUDISC is incremented.

I'll say once again that I don't believe implementing loss-free preemption will reduce the values of these counters.

Whenever you have an inter-RA cell reselection, the TBF is released, and a new one is setup in the new cell.

If you can get statistics on these counters on cell level, you should be able to identify the worst cells and see how you can redesign your RA.

Hope this helps.

Regards,SHELDON

safar - 9th May 2010 (13:12 GMT)

hi sheldon,

Buddy where are u?


Hi sheldon,

waiting for reply...


Hi sheldon,

ya buddy u are right i also go thr alex for same but i want to understand when this counter FLUDISC will increment i mean what happens actually when pcu buffer will be discarded while moving from one ra to another or one pcu to another pcu?

and i think if u see in alex with loss free preemption with this case ra and pcu reselction here tbf will not release immediately it will store llc frames in pcu abt 10 sec and in between if user try again then tbf will continue.

plz share if i am wrong.


Hi Safar,

The counters are defined as follows:

"FLUDISC:Number of times the entire contents of a downlink buffer in the PCU were discarded due to an inter RA cell reselection or inter PCU cell reselection (i.e. Flush message received in PCU that deleted the contents of a PCU buffer)."

"FLUMOVE:Number of times the contents of a downlink buffer in the PCU were moved to another queue due to a flush message received in the PCU."

I think you should look at your RA design. High values of these counters indicate many inter-RA cell reselections. You also mentioned inter-PCU cell reselection. How many PCUs do you have? What are the PCU utilizations?

I don't believe implementing loss-free preemption will help. According to ericsson, loss free preemption applies in the following cases:1.Preemption of essential PDCH2.TBF setup failure3.Intra cell handover of Dual Transfer Mode (DTM) connection4.Mobile switches from DTM to Packet Switched only mode (CS call release)5.BSS switches Abis transmission rate when Flexible Abis applies.

Hope this helps.

Regards,SHELDON


Hi sheldon,

here i have tbf release due to pcu reselection and ra reselection and i have high no in counter fludisc and flumove .

so can anybody plz explain exact meaning of this counter?

and if i activate loss free preemption then will this help?

because in loss free preemption llc will remain after tbf release for 10 sec so is it?

TBF Reallocation

safar - 28th April 2010 (03:33 GMT)

hi prabeen,

If tbf soft limit is crossed then also chance of tbf reallocation.

There is also one reason if u have edge priority is higjer than gprs .in this case only cs1 cs2 tbf reallocate

Pix - 27th April 2010 (12:40 GMT)

TBF reallocation is not a parameter, it is a procedure.When a TBF is allocated and suddenly one of the PDCH timeslot is preempted for a TCH allocation, then you see the TBF must be reallocated : from 4 PDCH it is now reduced to only 3 PDCH.This is a TBF reallocation.Causes for reallocation are mostly :1/ TCH preemption (= reduction of PDCH)2/ Optimization (= increase of PDCH because the cell is less loaded now than before)

3/ change of bias : the DL TBF is less used than the UL TBF, then DL TBF is reduced and UL TBF is increased

There are some other causes for reallocation, ut they are very rare and complex to explain :)

Cheerspix

Prabeen - 27th April 2010 (12:29 GMT)

Hi Pix,

Could you help me in explaining the parameter TBF Reallocation. I have seen this in an Alcatel material. Thats why asking you.

Preemption

Maram - 8th January 2009 (08:12 GMT)

Hi Pix,Very clear responseThank you a lot !

Pix - 7th January 2009 (17:54 GMT)

Soft Preemption means that a TCH is kicking out an allocated PDCH.

If you increase MAX PDCH, it means that more PDCH are allocated in the cell. But as soon as the "TCH load" of the cell is too high, the PDCH are released in order to make space to the increasing amount of TCH.

The number of PDCH that cannot be preempted = MAX PDCH HIGH LOAD, even if the TCH load is increasing. Those are non-preemptable PDCH.

To conclude: soft preemption means that your TCH+PDCH are too numerous in the cell. In order to avoid TCH congestion, the PDCH are deallocated.

Another thing: there are two types of preemption : soft and fast. It's not important to understand the difference, since the management of the preemption is fully automated (no parameter can be tuned). A PDCH is deallocated with soft preeption if it also carries the PACCH of one TBF.Otherwise, the PDCH is preempted with "fast" preemption.

Regards,pix

Maram - 7th January 2009 (16:12 GMT)

Hi all,

When I increase MAX_PDCH (ALCATEL BSS), soft premption increase enormously.Can any one explain that ? and what is soft preemption risks on EGPRS performance.

Host - 9th October 2008 (12:31 GMT)

Thanks pix you were very helpful.

pix - 9th October 2008 (11:45 GMT)

hello Host,

PDCH preemption occurs when a CS call is established on the cell by the BSC, on a timeslot that is used by GPRS.

PDCH preemption is divided in two types:fast preemptionsoft preemption

soft preemption is performed when the preempted PDCH carries a PACCH, or if the radio PDCH itself is not preempted, but one Abis nibble of its MEGCH will be.

during soft preemption the MFS has 4 seconds to reallocate this PDCH to another timeslot, in order to save the PACCH (save the PACCH = avoid a TBF drop), or reallocate in order to save the current MCS.

after 4 seconds, if nothing was done, fast preemption is done. If the reallocation (T1) was succesful, then nothing more has to be done.

fast preemption means that the PDCH is removed from the timeslot, without any delay. It will happen if the PDCH doesn't carry a PACCH for instance.

MFS and BSC just exchange a bitmap of timeslot "status". The MFS informs the BSC about which TS are allocated as PDCH or not, and the BSC tells the MFS which PDCH timeslot shall be deallocated ASAP.With DTM, there are now a little bit more info on this bitmap (about DTM timeslots).

regardsPix

Host - 9th October 2008 (09:30 GMT)

Can i have some details of PDCH Preemption and the different messages exchanged between MFS and BSC?

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