- This topic has 13 replies, 1 voice, and was last updated 4 years, 7 months ago by Rachael.
18th January 2009 at 21:05 #55431rkbGuest
I have found blocked call(SD block) in TEMS log file.
The layer 3 message was ‘missing immediate assignment’ while the MS requested channel(AGCH) (in the call attempt retry).
After 2 retry (as by the max_retransmission parameter)the call was blocked.and the layer 3 message was ‘No immediate assignment’.
What does that layer 3 messages mean?Does it mean to any specific cause for that Block?
I know that thats a SD block.But I couldnt find the reason for that block.There supposed to be no SD blocking.20th January 2009 at 12:25 #55432rkbGuest
why there was no immediate assignment command from the bts after ms requested for channel by RACH?..what may be the cause?..20th January 2009 at 18:12 #55433PixGuest
This is normal,
In case the SDCCH channels are all busy (= high sdcch congestion rate), then the BTS doesn’t have to reply to the MS.
The MS will then retry by itself, by sending a second and then a third CHANNEL REQUEST.
This is a standard mode of operation.
There is feature called “immediate assignment reject” that can be activated, so the BTS will send a message (IMMEDIATE ASSIGNMENT REJECT). This is not mandatory though. It works better this way though (generates less sdcch congestion), so I usually recommend to activate it.20th January 2009 at 22:25 #55434rkbGuest
Other then SD Congestion,is there any other reason which may cause bts doesnt have to reply to ms?
Because,I found no SD congestion for that cell fom the statistics.
“There is feature called “immediate assignment reject” that can be activated, so the BTS will send a message (IMMEDIATE ASSIGNMENT REJECT).”
thats mean we have to enable this feature to get “immediate assignment reject” in case of SD congestion?20th January 2009 at 23:09 #55435PixGuest
other possibility: the BTS never received the channel request in the first place. A problem of poor path balance (problem of UL reception), or just bad coverage ?
Or interference on the UL BCCH?
for the 2nd question: yes23rd January 2009 at 15:25 #55436TNSGuest
If the MS request is filtered using RACH_TA_FILTER is there any specific message via air interface?
BR23rd January 2009 at 17:45 #55437PixGuest
No DL message at all.
The MS will retry MAX_RETRANS times to send a CH_REQUEST but there’ll never be an answer from the BTS.7th February 2009 at 23:31 #55438TNSGuest
Yes, I know it…
So it’s another possibility (for answer of the main case )…
BR8th February 2009 at 08:27 #55439PixGuest
Oh, ok, i got it now. the question mark threw me off the scent 🙂8th February 2009 at 10:55 #55440TNSGuest
I was almost sure, so it was a question.
After you confirmation it was a “conclusion”.
(I know it = I knew it – my mystake ).
BR8th February 2009 at 14:33 #55441PixGuest
We are getting to a serious degree of subtlety here… 🙂26th January 2011 at 04:54 #55442mnrGuest
immediate assignment5th April 2011 at 19:13 #55443GSM ENTHUSIASTGuest
the missing immediate assignment would definetely mean there was no sd allocated.This could be due to more reasons other than blocked SD.simply put,an sd assignment failure.could be due to a lack of sd resources,radio issues,TX issues between BSC and BTS…etc1st August 2016 at 13:21 #55444RachaelGuest
how many call attempt retry is possible before call block?