SDCCH dimensioning for HR environment

raghdu, the paging success rate is a bit tricky… in my experience, the only paging failure might be caused by congestion in the paging channels of the cells or congestion in the BSC itself.
In Alcatel system, we do not count those failures, so we don’t have a paging failure rate (or a paging success rate), but rather a PAGING LOAD (amount of paging performed during one hour / capacity of the PCH channels).

I personally don’t think it is possible to compute a paging success rate, unless you know about the PCH congestion in each cell. Does your system provide this information ?

You can work with the PAGING LOAD though : you just have to set a paging load threshold (let’s say 10%) and if the paging load is greater than 10% it means you’re in overload 😉

All the phones you mention does not support Half Rate codec. They have AMR-HR codecs.

Hi, We’ve implemented FLP in one of the Network in our country. Everything is working properly except the SDCCH drop due to other reasons has increased.

Do you have any solution to trace out the SDCCH drop due to other reason?

Pls reply.
Thanks in advance.

I have the below problem at one of site. Below is some of the information extracted from BTS Error Log:

The probelm is high Handover ping pogs. We replaced one TRU in Sector 3 because sector 3 couldnt handover to other sectors.

FAULT:AO: AO_TS, inst 6: Raise, TRA (REMOTE TRANSCODER COM LOST)

FAULT: ATSR:0, cease ec1 TERR LINK 6

TRACEH:Incorrect SAPI : 1
TRACEH:Incorrect SAPI : 5 OR 6

Hi Everyone,

Pls clarify me what are the probable solutions to find the reasons for HIGH SDCCH fail along with there solutions,if any in particular to alcatel networks.

Thanks

hungtran

sdcch failures, 3 possibilities =
1 – radio problems (low coverage, interference, ghost rach, timer issue …)

2- congestion

3- BSS (hardware failure, VERY rare in this case)

find which is your current issue, then analyse the problem with drive test or advanced QoS analysis. Keep in mind that average SDCCH failure = 20% in alcatel system, and up to 50% if going through satellite Abis.

Hungtran,

In Alcatel BSS, the SDCCH failure rate threshold is 20%.

Below 20% : it is good.

Subscribers will not “feel” anything wrong with your network, it is a perfectly normal network.

Trust me.

Now, you have to check the SDCCH Preparation Failure due to Congestion. If that is higher than 2% or 3% (at busy hour), then you have SDCCH congestion problems.

Hungtran,

Those failures rates do not represent the reality, and the subscriber will not “feel” the failure at any point ! It is fully transparent for the subscriber.

For dense urban sites, the failure rate is about 5% to 10%, and for rural sites, it is about 20% / 30%.

It is the same in all Alcatel networks, B5, B6, B7 and B8. And I’ve worked on many Alcatel networks… It’s up to you to trust me or not, but you can always contact RTAC.

Which country are you in ? Hungtran sounds Vietnamese ? I’ve been in Vietnam too, for all three operators (Vietel, Mobifone and Vinafone) 😀