How to decrease High SD assignment failures

[mail2paturi]

Dear All,

In our network we are facing High SD assignment failures.
Request your help in Reducing the same by some parameter tuning

Kindly suggest which parameters can be tuned as we have done all the Physical optimization but still no use and this count is in large number

System is ZTE as i request help by the parameters name is other vendor operators so that i can search and implement the same.

If any ZTE expert can help me out it would be far better.

Thanks to all in advance

[oswe]

what causes are the failures ? congestion ? phantoms rachs ? check interference bands in bcch to see interference ...

[mobilis]

Dear Freind

Please to specify the reason of the Failure , in ZTE system we have the counters of SDCCH assignment for MOC, MTC ,Call reestablishment, emergency calls , location update ,and other causes , in fact you can know witch service is affecting your assignment . after that we discuse the reason ,

BR/

[mail2paturi]

Dear Freind

Please to specify the reason of the Failure , in ZTE system we have the counters of SDCCH assignment for MOC, MTC ,Call reestablishment, emergency calls , location update ,and other causes , in fact you can know witch service is affecting your assignment . after that we discuse the reason ,

BR/

Dear Bro,
I have gone through all the counters and unable to find the related counters for the same.
Can you give me details which are the counters for the terms as ur mentioned so that i can discuss with the vendor further.

[mail2paturi]

what causes are the failures ? congestion ? phantoms rachs ? check interference bands in bcch to see interference ...

Dear Bro,

No congestion in the site, and didnt find any interference in the site as this issue is entire network level no specific to one or two sites

[oswe]

then it is a registering in the network problem ? please compare the LAC that all cells belong to.

[usama0795]

dont know about ZTE but common parameters when handling SD Assignment Failure : increase max_retans / increase tx_integer / enable re-transmit immediate command message to MS / check parameters for dynamic allocation of SDCCH / verify rxlevel_access_min thats its set not to too low value / increase parameter Random access error threshold / trying re-mapping sdcch to hopping TRX if mapped on BCCH and vice versa / verify the BCCH-BCC combination plan as if TSC which is equal to BCC and BCCH is matched phantom RACHs can increase..............

[mobilis]

Dear Bro
sorry for the delay
the BSC version is ( iBSC V6.20.61).
the counters are

C901250020:Number of SDCCH assignment attempts(MOC)

C901250021:Number of successful SDCCH assignments(MOC)

C901250022:Number of unsuccessful SDCCH assignments(MOC)

C901250023:Number of SDCCH assignment attempts(MTC)

C901250024:Number of successful SDCCH assignments(MTC)

C901250025:Number of unsuccessful SDCCH assignments(MTC)

C901250026:Number of SDCCH assignment attempts(call re-establishment)

C901250027:Number of successful SDCCH assignments(call re-establishment)

C901250028:Number of unsuccessful SDCCH assignments(call re-establishment)

C901250029:Number of SDCCH assignment attempts(emergency call)