problem in the Paging causing degdation on SDCCH blocking and DCR and INHSR

[wael]

Dear experts
We have strange thing on our network , during the weekend the paging request increase in two LAC both of them having 5 BSC the paging / sec reach to 35 but the problem that we get degdation on SDCCH blocking and DCR and INHSR and the strangest thing that the call volume decreased , as action we change the paging attempt from the MSC side from 4 to 2 but it was not working then we reduce the size of the BSC paging buffer from open to 100 but it was working

Any explanation will be appreciated

[zhanglw268]

What's the below parameters setting in your cells?
wait_indication_parameters
ccch_conf
bs_ag_blks_res
bs_pa_mfrms
extended_paging_active
max_retran
tx_integer
rr_t3101

What's the below statistics in cell level?
ACCESS_PER_RACH
OK_ACC_PROC_SUC_RACH
ALLOC_SDCCH_FAIL
ALLOC_SDCCH
CHAN_REQ_MS_BLK
ACCESS_PER_AGCH
CHAN_REQ_MS_FAIL

Were you having high/unusual chan_req_ms_fail building up gradually, then ALLOC_SDCCH_FAIL and CHAN_REQ_MS_BLK were high at the same time in a lot cells?

[wael]

Below is the setting is parameters
wait_indication_parameters

6

ccch_conf

0

bs_ag_blks_res

2

bs_pa_mfrms

2

extended_paging_active

1

max_retran

1

tx_integer

12

rr_t3101

2000

I don’t think there is any issue on the parameter setting
Regarding to the below stats , all of them are going very high due to the very high paging that come suddenly from the MSC , but don’t know what is the reason for this paging
I can say may be the degradation in KPi’s due to BTS stuck =èdue to the high paging but I’m not sure .
. yesterady I split the LAC ,at least to reduce the paging and monitor the stats . till this momment no issue and

I have one senario let ‘s suupos there are a lot of traffic in some cells ( congstion ) under one LAC, what will happened for the MT calls , I think will be like the MS out of coverage . I mean the network will be busy and then the MSC will send the paging over and over againe on this LAC . as respons the PCH will be congestion but why RACH and AGRH and SDCCH why they respond to thos paging at all cells in the LAC .that’s why I split the LAC .

Till this moment every thing is ok

[wael]

Below is the setting is parameters
wait_indication_parameters6

6

ccch_conf0

0

bs_ag_blks_res2

2

bs_pa_mfrms2

2

extended_paging_active1

1

max_retran1

1

tx_integer12

12

rr_t31012000

2000

[zhanglw268]

Did you see below event/alarms a lot in the system while the problem existed?

[0] Flow control procedure has started barring normal calls from access classes 0-9 - FMIC - Warning -/-.
02 .

Please note that the additional informaton field is 02 not 01 or 03.

[kais]

see attached file for 3G paging analysis...

[wael]

Yes the below alarms existed on many cells , do you think the problem was due to the flow control, if yes can you explain?

I’m thinking if the MS was blocked due the flow control on certain cell , may be can camp on other cell specially if the MS was moving . and then these Scenario will be repeated over and over again .

[zhanglw268]

Final question, What's rach_load_threshold value in these alarms cells?

[wael]

Many thanks , pls find below the setting of the flow control

rach_load_period

8

rach_load_thresh

117

ccch_load_period

8

tch_flow_control

0

flow_control_t1

5000

flow_control_t2

15000

[zhanglw268]

The problem you had is exactly the same problem which happened in another network in the same country more than 1 years ago. I had the explanation at that time and also shared with the people in this network.

This is network cell level parameters setting issue, with current settings, this can happen at any time if the conditions are right.

You shall be able to get the explanation and solution as there are still people working there along with you.

If you need further help, please let me know.