MC02d – ALU, help, please!

denis,

the LU follow-on is when the MS performs a LU and asks for a TCH at the same time : during the sddch phase, the location update is performed and then the BSC allocates a TCH to the MS, for the call.

Basically, the MS wants to do a LU and then a call. I don’t know when this ever happen, i can’t find an example… if you have any idea, you’re welcome to share.

In terms of counters : how many MC02d and MC02a are counted at busy hour ? MC02d should be very low.

Regards
pix

denis,

i’m interested to know why your MS’s are asking for LU follow-on procedure !

In 3GPP TS 44.018
LU follow-on means ESTABLISH INDICATION contains a L3 message with an MIE message type set to LOCATION UPDATING REQUEST and with an MIE Location updating type not set to a RESERVED value and a bit FOR set to 1.

I’ll try to check out the 3GPP again.

Regards
pix

hi,

go there
http://www.3gpp.org/Specification-Numbering

for GSM, check out series 44 and 45.

click on serie 44
choose 44.018
http://www.3gpp.org/ftp/Specs/html-info/44018.htm

then go to release 8 part.
and click on 8.12.0
http://www.3gpp.org/ftp/Specs/archive/44_series/44.018/44018-8c0.zip

regards
pix

Hi all! Hi mr.Pix!
What can i say now? Some things 🙂
1) for such cells E2E CSSR is VERY low (about 20-40%). Mr.Pix i saw you were interested in this question – maybe it can be interesting to you.
What a peculiar situation!!!
on one hand: “legal” CSSR is higher than best 150%!!
on other hand: E2E CSSR is lower than the worst 20-40%!!

2) all these SDCCH successful seizures (due to MC02d) do not go into a calls. i think so because for night hours mc02d is about 130-150 per hour but mc140a is usually low – 1-5 per hour. Am i right?

hm… could it be a cunning device?

i would get some – to “improve” our KPIs ))))))))

Hello, mr.Pix!
i think the only thing i can do – is to collect Abis traces.
but i have no experience in analyzis. so i already have questions

the first:
below you can see the Message “CHNRQRD” – channel required 🙂
all I’m able to see is Reference number and it = 19.
but how i can define the cause for the request? and TA? according to all sources this message must contain such info.

E-GSM 08.56 (LAPD 4.0.2) (LAPD) INFO (= info frame)
info frame
——-0 Address field ext. 0
——0- Command/Response 0
000000– SAPI 0
——-1 Address field ext. Last octet
0000001- TEI 1
——-0 Frame Type Information transfer format
0010011- N(S) 19
——-0 Poll Bit don’t poll
0101110- N(R) 46
E-GSM Alcatel Abis RMS, Release B9, ED03 Released (RMS) CHNREQIR (= Channel required)
Channel required
00001100 Message discriminator 12
G bits Common channel managment msg
T bit msg is to be/was considerd transp…
00010011 Message Type 19
Channel number
00000001 IE Name Channel Number
—–000 Time slot number 0
10001— C bits Uplink CCCH (RACH)
Request reference
00010011 IE Name Request Reference
00010011 Random Access Reference 19
00011— T1′ FN mod 32 3
***b6*** T3 FN mod 51 30
—11001 T2 FN mod 26 25
Access delay
00010001 IE Name Access delay
–000001 Access delay 1
00—— Spare 0

Many thanxes

hi,

the cause of the request (cause establishment) is received by the BTS in the Channel Request from the MS, but is not forwarded to the BSC in the Channel REquired.
I just found out about this thanks to your question.

So on the abis, you cannot know what is the cause of the establishment. However you can see it in the “Establish indication” which is sent a bit later. It is in the encapsulated protocol “DTAP”, “Message Type”.

The GSM phase 2/2+ MS may indicate in the LOCATION UPDATING REQUEST message that it has a
follow-on request pending. If the network reports to the MS in the LOCATION UPDATING ACCEPT (which arrives at the end of the SDCCH “DTAP” phase, after authentication and ciphering)that the MS can proceed its follow-on request then the MS sends a CM SERVICE
REQUEST to the network (message transparent to the BSS).

In the Estab Indication, do you see “follow-on” = 1?
In the Loc Upd Accept, do you see the field related to “follow-on request”?

It is the MSC that decides to accept the follow-on or not.
If MSC accepts it, then the MS will send a CM Service Request after it received the Loc Upd Accept from the network.

Regards
pix

Denis,

MC92xxx are counted by the BTS, not by the BSC ! (new B10 counters…)

IE Name Request Reference = Random Access Reference = 19

Trace during night is a good idea.
If cell deep into the LAC, then I would assume those subscribers are could not connect to their operators and then they try to attach to your network in order to establish a call.

Check the IMSI/TMSI of those MS !

Regards
pix