CSSR VSAT

[usama0795]

Hi Experts can anyone comment on how to improve CSSR of VSAT sites??? Vendor is NSN.....

[khurrambilal01]

Hi Usama,
For NSN, Because there is a lot of load on signaling (Because unike Huawei/Siemens & ZTE, in NSN BTS doesn't perform any action on MRs and just sends it directly to BSC that's why Signaling load is very high) so because of this signaling load CSSR is bad (SDCCH ABIS FAIL calls, T3101 expiries due to load on SDCCH on ABIS etc).
Attached is a document for imrpoving KPIs for VSAT NSN sites, I have seen alot of improvement in KPIs after changing these parameters).

Please add to my REPs if you like the document.

[usama0795]

hey thank bro but cant seem to find b/m parameters need some support; new to NSN 2G what does UTPFIL means.....


T3101_ offset:
T3101 timer supervises SDCCH establishment procedure. It is started, when a channel isallocated and stopped when the MS has correctly seized the channels. If the dedicatedchannel is not established before T3101 expires, the allocated channel is released. Whensatellite Abis is used T3101 timer value shall be increased according to Abis delay i.e.T3101 (for satellite Abis) = T3101 (for terrestrial Abis) + T3101_ offset.The recommended settings of T3101 offsets are different for “standard” setup of SatelliteAbis and for Enhanced Satellite Abis (as depend on satellite delay):- T3101_ offset for Satellite Abis is recommended to be of 560 msec (i.e. 2x 280 msec)- T3101_offset for Enhanced Satellite Abis is recommended to be of 840 msec (i.e. 2x420 msec)Note: T3101_offset is available via UTPFIL.
Phone_case_table:
defines maximum amount of suimultaneous SDCCH establishments in satellite Abis. Interrestrial links the equivalent parameter exists and its setting depends on TRXSIGcapacity: default value for satellite Abis is the same which is currently used for 16kbit/secterrestrial Abis, but at the same time greater TRXSIG capacity is recommended for satellitesetup (i.e. at least 32kbit/sec for Satellite Abis). For enhanced satellite Abis even moreconservative setting is recommended.The recommended settings of phone case table are different for “standard” setup ofSatellite Abis and for Enhanced Satellite Abis (as depend on satellite delay):- phone_case_table for Satellite Abis is recommended to be of 20,- phone_case_table for Enhanced Satellite Abis is recommended to be of 10Note: Phone_case_table is available via UTPFIL.

[alert181]

Hi Usama,

One of the best ways to improve CSSR on VSAT sites is to put them on a separate LAC (if you haven't already done so).

BRs,

[usama0795]

already in a seperate LAC bro and i did increase T3101 from 3 to 5 seconds / retrnamission to 5 / retrnamission interval to 32 and changed mapping of SDCCH too / change perodic location update timer to 240 but no impact still CSR is at 50%.......i just need to know if there is anything more i can do from my end OR its a pure transmission issues and its a bottleneck.....

P.S Khurram....cant seem to find the below parameter as well.........


PCU_PFH_FN_SYNC_TIME_MA:
This parameter is used to define synchronization timeout. The longer Abis delays the moretime is needed for PCU/Abis synchronization (initial time alignment and block alignment)and the value that is used for terrestrial links (3000 msec by default) is no longer sufficient.The recommended settings of PCU_PFH_FN_SYNC_TIME_MA are different for“standard” setup of Satellite Abis and for Enhanced Satellite Abis (as depend on satellitedelay):- PCU_PFH_FN_SYNC_TIME_MA for Satellite Abis is recommended to be of 5000msec,- PCU_PFH_FN_SYNC_TIME_MA for Enhanced Satellite Abis is recommended to beof 9000 msec,Note: PCU_PFH_FN_SYNC_TIME_MA is available via UTPFIL.

[Shakeel_15]

Hello,

For those who operates on VSAT have usually the high SDCCH Mean holding time and it can be 5 times greater as compare to normal ABIS Site.

Check the SD Mean holding time of VSAT Sites and try to optimize it, and it will reflect positive in CSSR.

Feel free to let me kniow for any more query.

BR

Hi Experts can anyone comment on how to improve CSSR of VSAT sites??? Vendor is NSN.....

[khurrambilal01]

Change RACH retransmisison to 2 for VSAT sites, LAPD size should be 64kbps or atleast 32kbps per TRX.
Change BMA (BTS measurement averaging to 4), T3101 to 5,T200 SDCCH to 1260ms

[khurrambilal01]

About UTPFIL PFB the description:

UTPFIL parameters
The UTPFIL parameters are stored in the Unit-type-associated Parameter File (UTPFIL) of the BCSU unit.
The UTPFIL file is empty when it is taken to the BSC. You can change the UTPFIL parameter default values by adding the data into the UTPFIL file of the unit in question.
A record of the UTPFIL consists of the identifier of the parameter (double word) and the parameter value (double word). The records of the UTPFIL file are filled from the first free record onwards with the local MMI on the BSC site.

[Shakeel_15]

Hi,

Also delete excessive SDCCH if present.

Try to equalize the SDCCH distribution among TRXs and if possible avoid extra things like Cell Broadcast service.

BR

[khurrambilal01]

Also disable queuing because it's not recommended for VSAT sites.