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# TCH congestion

Viewing 15 posts - 1 through 15 (of 19 total)
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• #57939
sd
Guest

some of our cells have no congestion while some have very high congestion for the same number of TCH channels. what might be the reason, can anyone help me out??

#57940
Pix
Guest

High amout of traffic

#57941
sd
Guest

acc to our Erlang B table if we calculate the traffic, we still have caacity but we get congestions before reaching the rated capacity. In some cells we have TCH congestion even in case of low traffic.

#57942
Pix
Guest

could you give me some numerical values, please ?

check that all your TRX are up & running (availability, alarms ?)

#57943
aso
Guest

This could be that those cell might have high interference.

#57944
Rex
Guest

Hi sd,
Check traffic for each TRX. Do all TRXs having any values? Perhaps one of TRXs has 0 Erl. If Yes, work on that TRX (reset TRX, reset corresponding TCUC, change TRE, etc).

#57945
sd
Guest

hello pix,
in one of our site for 56 TCH channels (half rate), traffic is 26.83 erl and the corresponding congestion is 26.59% while for the same cell, at traffic 35.62, congestion is 2.15%.

#57946
pix
Guest

could you check how much is the traffic carried in half rate, and how much in full rate ?

i suspect there i either:
1/ no half rate in the cell (parameters wrongly set ?)
2/ some trx’s are down

cheers,
pix

#57947
sd
Guest

For 56 HR TCH channels,total traffic is 50.49 Erl where 4 Erl traffic is FR while 46.49Erl is HR traffic with 53.64% TCH congestions.

#57948
Pix
Guest

SD,

In each situation, 56 HR TCH:

1/ Traffic = 26.83 erl, Congestion = 26.59% —> Very abnormal, congestion way too high

2/ Traffic = 35.62 erl, Congestion = 2.15% —> Normal

3/ Traffic = 50.49 Erl, Congestion = 54% —> Normal

In the first situation, I think the capacity you compute is not corret. Not all TRX are actually able to carry traffic.

(or all TRX are OK but they are able to carry only full rate, not half rate)

In other cases (2 and 3), no visible problem.

#57949
Ayat
Guest

DEAR ,ALL

REALLY I APPRCIATE YOUR SUPPORT ,

I NEED TO UNDERSTAND THE GSM CALL PROCESDURE OUR VENDOR USE COMPLEX DESCRIBTION FOR THE PERFORAMNCE SYSTEM SO . IT IS DIFFECULT TO UNDERSTAND IT ,

COULD YOU HELP US TO DEAL WITH THESE COUNTERS.

SDCCH Dropped call total number
SDCCH attemption total number
SDCCH overflow total number
SDCCH allocate failure number in busy time
Number of SDCCH seizure attempts for assignment
Number of SDCCH seizure success for assignment
Number of SDCCH seizure failure for assignment
Number of SDCCH seizure attempts for handover
Number of SDCCH seizure failure for handover
Number of SDCCH allocation success for assignment
Number of SDCCH allocation failure for assignment
Number of SAPI3 link establishment requests on SDCCH (MO-SM)
Number of SAPI3 link establishment requests on SDCCH (MT-SM)
Number of SDCCH drops due to handover failure
Number of SDCCH drops
Number of SDCCH assignment attempts
Number of SDCCH assignments success
Number of SDCCH assignment failure
Number of SDCCH drops due to loss of contact with RANA
Number of SDCCH drops due to LAPD link failure
Number of SDCCH drops due to OMC-R forced release
Number of SDCCH drops due to forced release by other calls
Number of SDCCH drops due to handover failure
Number of SDCCH drops due to other failure
Number of SDCCH drops
Number of RANA link releases due to other cause on SDCCH
Number of SDCCH short messages drops
Number of SDCCH seizure attempts for assignment
Number of SDCCH seizure success for assignment
Number of SDCCH seizure failure for assignment
Number of SDCCH seizure attempts for handover
Number of SDCCH seizure success for Handover
Number of SDCCH seizure failure for handover
Number of SDCCH allocation attempts for Assignment
Number of SDCCH allocation success for assignment
Number of SDCCH allocation failure for assignment
Number of SDCCH allocation attempts for handover
Number of SDCCH allocation success for handover
Number of SDCCH allocation failure for handover
Number of SDCCH assignment attempts
Number of SDCCH assignment success
Number of SDCCH assignment failure
Number of SDCCH handover failure
Number of SDCCH handover success

could you explain

Number of SDCCH assignment attempts 18149
Number of SDCCH assignments success 17745

Number of SDCCH allocation attempts for Assignment 18150
Number of SDCCH allocation success for assignment 18149

what does mean allocation

does this procedure before or after the assignement

what does mean siezed and alloated assign

#57950
Pix
Guest

Attempts mean : the SDCCH channel is given to the MS (the BSC have successfully allocated the subchannel in the cell), in other words the reference of the SDCCH timeslot & subchannel is sent to the MS in the Immediate Assignment.

Success : the MS has replied to the Imm Asg, and therefore the MS has succesfully landed on its SDCCH subchannel.

if you have 100 attempts and 90 success :

it means 10 attempts did not becme success. 10 MS have not succeeded to land onto their SDCCH. Probably radio problems : the SDCCH is interfered, or the MS is too far away (bad coverage)

#57951
Ayat
Guest

Hello pix

thanks

Success : the MS has replied to the Imm Asg, and therefore the MS has succesfully landed on its SDCCH subchannel.
is that mean success is seized .???

#57952
Pix
Guest

success = seized, yes.

#57953
Ayat
Guest

hello All

Number of MOC random access attempts = 926

Number of successful MOC random accesses= 883

Number of CM service requests of MOC= 711.

926-883=43 why failure 43

883-711=172

could you expialn these number??

from the defination we see that Number of successful MOC random accesses=Number of CM service requests of MOC but in the result it is not

Number of CM service requests of MOC= 711
This counter counts the number of accesses due to CM SERVICE REQ of MOC. After BSC receives the EST_IND message, if the access cause in the layer-3 information in this message is “CM SERVICE REQ”, this counter increments.
This counter is used to find out the frequency of the access due to CM SERVICE REQ of MOC.

Number of MOC random access attempts = 926

It represents number of random access requests due to MOC. If
TA does not exceed cell range, BSC treats random access
request as valid MOC and increments the counter.

Number of successful MOC random accesses= 883
It represents the number of successful random accesses when
BTS assigns a channel to MS due to MOC. After successful
access, MS sends EST_IND to BSC through BTS. Counter