Look for ABIS Rsl congestion. The SACCH itself, on the Air interface, cannot be congested. But the transfer through the Abis link might be a problem, especially with Abis over IP. I forgot the exact vocabulary they use in Ericsson…
Also, ensure your BSC is not overloaded at the signalling plane level.
Thanks for suggestion. We are currently testing LBS (Location Based Service) and during the test cases found that if there are more requests towards the BSC from Location server this kind of problem occurs. I have 3 Qs,
1. How can you say that SACCH on Air interface CANNOT BE congested.
2. During such tests of huge location requests, SDCCH goes to BLOC state. Is this be related?
3. If its Rsl congestion then normal calls will also be affected?
Why do you think the SACCH is congested ? LBS doesn’t use SACCH, does it ?
Does it use SACCH to transmit a kind of SMS ?
SACCH has a static “throughput”, which is reserved. It cannot be shared, cannot be preempted, cannot be congested. Every call has its own SACCH capacity. It’s static.
LBS over SACCH is probably mapped on the same SAPI as “SMS over SACCH”, which has the lowest priority when the ABIS RSL is congested.
So yeah, definitely, look into your RSL.
SDCCH blocked –> YES, it is due to the LBS activity.
If RSL congestion –> depending on vendor strategy, some services will be delayed or even blocked. Typically, SMS are probably the first messages to be discarded, to avoid getting in a hard RSL congestion.
Viewing 4 posts - 1 through 4 (of 4 total)
The forum ‘Telecom Design’ is closed to new topics and replies.