Preparation failure, during the TCH assignment ? The only experience I have about this failure was linked to a missing patch on the NSS side. It impacted heavily all cells of the network, as soon as they were congested. I think it was due to a wrong management of the Directed Retry or the Queuing.
If it only happens a little bit to few cells, I can’t say. I think nobody knows exactly why there are these failures 🙂
This is a problem of compatibility betwenn Huawei software and Alcatel software. I recommend you escalate this problem quickly to your program manager, and ask for both vendors to perform tests and traces.
The TCH assignment BSS preparation failures lead to a failure in TCH assignment, so people can’t make calls. Check out the formula of this indicator if you want more details…
Remote TC drop can be due to
– Abis link failure
– TRE or SUM card failure
– BSC board failure
– transcorder board failure
try to see which sites are getting a high drop due to RTC. If only one cell, suspect a TRE problem. If 3 cells from one sector, suspect Abis failure (or SUM ?).
If all cells in BSC, suspect BSC problem
If all cells in transcoder, suspect transcoder issue.