high RRC setup failures,possible reasons

[shahram]

Hi,
We have RRC setup issues (RRC setup request are being sent for 4 times without any response from NodeB) in all 3 sectors of a 3g site,which result in blocked calls . investigations shows high downlink transport channel BLER while the RSCP and EcN0 is good, availability is 100% too. what could be the possible causes?

regards,

[SHIVAM]

Probably it seems that Node-B is not hearing the RRC request sent from UE, hence no reply/command to setup the RRC. There may be several reasons for it.
Have you checked RTWP Value for that site, also it may be due to Hardware Problem. Plz check if any alarm coming on the site else just try to commission the site again and observe. You may also get the site parameter as well as transmission media verified.

[tharinduwije]

Hi,

This could be due to High RTWP (May be external Interference) or due to hardware issue in NodeB.I have attched a document that may be useful in troubleshooting access failures
37008

[samuraial]

Do a restart of the site as usually that solves 90% of the problems in Huawei equipment or check the board utilization of the NodeB as if board utilization is high usually reject(RRC SSR drops as in your case).
Or collect the NodeB brdlog from M2000(U2000) at software tab -> NE->(select your NE name)->other(here select BRDLOG and transfer from NE to OSS client.) just use the compress option and open it with FMA to analyze it.
This way you will have a better idea of what is happening with your NodeB :)

B/R

[Inception]

if your vendor is e******* check the preamble ramping of PRACH in power control ,as the mobile can not listening of NODEB .

CHEERS

[oucht79]

check the Packet loss or HW issue in the BBU because it's related to commun issue in all sectores

[justdream]

Hi,

This could be due to High RTWP (May be external Interference) or due to hardware issue in NodeB.I have attched a document that may be useful in troubleshooting access failures
37008

Dear I read in your document that PreambleRetransMax
should be 20 otherwise it will affect UE access Failures however I found in my network different values like 7 & 30
Could you please explain to me what these values mean?

Excuse me it's still my first days in 3G world..

[linhhy]

Hi,
We have RRC setup issues (RRC setup request are being sent for 4 times without any response from NodeB) in all 3 sectors of a 3g site,which result in blocked calls . investigations shows high downlink transport channel BLER while the RSCP and EcN0 is good, availability is 100% too. what could be the possible causes?

regards,

It's quite old document.