- This topic has 154 replies, 1 voice, and was last updated 13 years, 8 months ago by pix.
10th April 2007 at 14:54 #35583PixGuest
I just found this rule to be checked :
T_GSL_Ack (BSC) > T200 (GSL) * (1 + N200 (GSL))
N200_GSL (BSC) : Maximum number of re-transmissions on a GSL link.
T_GSL_ACK (MFS) : Supervision of MFS acknowledgements on BSCGP.
T200_GSL : Supervision of acknowledgements on the GSL link.
Pix20th April 2007 at 09:10 #35584VictorGuest
I have problem in understanding how Timing alingnment is done on the abis interface for the Trau frames in UPLINK ,and DOWNLINK direction,for different codec scheme frames(FR,HR,AMR).Can anybody send me a trace of trau frames on abis interface .
with warm regards..
Victor3rd May 2007 at 08:55 #35585AyatGuest
ould you explain what is frequency hopping in as simple as that ( i need to understand tht by use sample way ) thanks3rd May 2007 at 08:58 #35586AyatGuest
Why we use Half rate tech. although it has disadvantage .
in our network we use HR we are going to disable it to know what is the effect of HR on our network.11th May 2007 at 11:35 #35587ZeusGuest
Please tell me what would be the effect of Ghost RACH to Paging Load and AGCH Load.
Also, what would be the effect in the SD resource?11th May 2007 at 14:53 #35588pixGuest
ghost rach will trigger allocation of an SDCCH at the BSC side.
the following msg will be sent over abis:
channel activation acknoledge
immediate assignment command
and finally, on the air interface : immediate assignment command, from BTS to the MS (on AGCH).
Ghost RACH increases AGCH load and increase the number of SDCCH allocated by BSC (after the channel required, the BSC books a SDCCH channel)
So ghost rach can also lead to SDCCH congestion.
NO impact on PCH.
Regards.13th May 2007 at 10:55 #35589rajatGuest
can somebody tell me how the Ghost RACH are originated in the system.13th May 2007 at 12:06 #35590PixGuest
From the same place ghost are originating from… nobody really knows 🙂
It could be one of the following:
BTS internal equipments generating electromagnetic disturbances
External radars (army for instance)
External electromagnetic devices (alarms systems, remote controls…)
Other network operators (from other countries)
Atmospheric disturbances, and so on…
Favorite answer : generated by the BTS itself…13th May 2007 at 13:56 #35591Yogesh ChoudhariGuest
I am working on G1800 network, and we are using Nokia equipment for front end and also for back end ( NSS). My n/w is having high SDCCH failure rate.
When i see the reason for SD failures on clear code level, I got a high count of clear code on Establishment indication message corruption.
Can this be a result of wrong POC parameter tunning, if no then can anybody tell me the other possible reason.14th May 2007 at 12:17 #35592PixGuest
What is POC ?
so you’re measuring a high SDCCH failure rate on “all” cells, during each hour of a day, every day of a week ?
Is it related to the amount of traffic in your network ? (for instance, during the night, there is no traffic, so you don’t see sdcch failure, do you ?)
If the failures happen all the time, even when there is no traffic, you might be getting some country wide interference (another operator ?).. or possibly some problem with other sites collocated on the same pole (did you co-locate your gsm900 sites with dcs1800 sites ?)
If the failures only happen when TCH traffic is occurring, then you can investigate parameters settings (i’m thinking about timers and repetition of RACH…)
Just giving some leads, about BSS side. I’ve got no knowledge about NSS side.
Pix30th May 2007 at 15:07 #35593Yogesh ChoudhariGuest
Thanks Pix for reply and sorry for giving reply so late.
POC is power control parameter.
In our network we are observing this problem sevearly during network busy hours i.e. when traffic is huge. For RACH we have done some fine tunning on RACH repetation and the multifram spread slots. But it is not giving any improvement.
Can you please share something on timer level.
We have some amount of SD fail because of T3101 expirory also30th May 2007 at 16:14 #35594PixGuest
The power control will not affect your SDCCH assignment success.
Exactly, how much is your “SDCCH ASSIGNMENT FAILURE RATE” ? (in average for your GSM1800 cells)
Regarding other answers, i’ll have to study which timers are used during this phase. To simplify the problem:
your BSC is getting a “CHANNEL REQUIRED”, then sends a “CHANNEL ACTIVATION” to the BTS, then receives a “CHANNEL ACTIVATION ACKNOLEDGMENT”.
Next step : the BSC is sending the IMMEDIATE ASSIGNMENT COMMAND, directly to the MS.
It is at that point that you measure a failure : the MS doesn’t answer the assignment command, or, if it does receive it, it is the BTS that doesn’t receive the SABM from the MS.
If messages are not received, it means either the BTS or the MS stop listening… so there might be a timer expiry. Check T3122 / T3120 / T3101… those are the timers that are quite obvious, but there might be additional timers somewhere… I’ll look for it when i have more time. But i think you can quickly find your answer about timers in the 3GPP documentation.
Check 3GPP TS 04.08 “mobile radio interface layer 3 specifications”, especially the chapter 3.3 “RR connection establishment”.13th June 2007 at 16:18 #35595papisGuest
Please tell about these KPI:
Utilization of VLR
We have of course 3 MSC
Thanks25th June 2007 at 07:22 #35596AjayGuest
How can we reduce PCH load, if on complete network how or for a single sector too?14th July 2007 at 08:50 #35597HIAGuest
Anyone knows how FLP works? Does is need BSS sync.