- This topic has 10 replies, 1 voice, and was last updated 12 years, 3 months ago by
.
-
Posts
-
Hi Guys,
Random Access Success Rate has the formula : 100 * No. of successful random accesses / No. of random access attempts. Can anybody tell me what is a successful random access? I mean when this counter is pegged?
you need to find an ericsson guy… i’m the alcatel guy 🙂
You can give the Alcatel’s definition for it, I don’t think there will be much difference 🙂
That’s the thing, we don’t have those in alcatel.
Let’s try to guess.. the MS starts with a channel request on RACH, the “Channel Required” reaches the BSC, and then is counted as a “random access attempt”.
The BSC sends a Channel Activation to the BTS, if the SDCCH is not congested. Counted as a “SDCCH Request”.
The BTS replies with a Channel Activation Ack (not counted)
Then the BSC sends a Immediate Assign Command, counted as a “SDCCH allocated”.
Maybe in your formula, this is the ratio CHANNEL ACTIVATION / CHANNEL REQUIRED ?
I really cannot be sure… this indicator is not provided by alcatel. it can be computed manually though.
Got the answer. But it creates another confusion.
Successful Random Accesses are all except failed random accesses.The failed random access counter is incremented for a Random access received with too high TA, values that are not used or in case of “software file congestion”.
That means every RACH attempt with less than max TA and defined cause value is a successful Random Access. But Ericsson says poor BSIC planning can be a cause of bad Random Access Success Rate, how is this? Even a phantom RACH intended for another cell must have a valid cause value and hence it must be treated as a Successful Random Access.Any idea?
you’re right, a RACH on a BCCH is not “failed” even though there is a poor BSIC-BCCH plan.
in my opinion, the only problem could be a RACH sent on a BCCH frequency that is used as well few kilometers away. In this situation, the second cell might receive this RACH with a distance > “rach timing advance”.
Hi all.
What is the meaning of Um interface, thus what does it stands for. I know it interfaces the MS and BTS. But what is the meaning of U and m in Um interface.Thanx.
Hello and welcome to internet.
Wikipedia / Um interface
“It is called Um because it is the mobile analog to the U interface of ISDN.”Regards
pix‘Um’ is an acronym for “User Mobile”
hi paraHO,
glad to see you are still around !
regards
pixHi Pix – thanks. Just can’t keep away from the forum 😉
- The forum ‘Telecom Design’ is closed to new topics and replies.
