- This topic has 7 replies, 1 voice, and was last updated 12 years, 6 months ago by Chathura.
29th June 2008 at 08:40 #52954HO from WCDMA to GSM faiureGuest
can any body hlp me with the phenomena that I faced when HO occur from 2g to 3g is successful but vise versa is fail most of time what could be the reasons??????29th June 2008 at 18:02 #52955peyoGuest
what do you mean by “fail”? can you see 2G neighbors when on 3G?
if no check for classmark update message (with K15) when arriving on 3G cell. Some handset are failing on that point.
what brand of MS are you using?29th June 2008 at 20:08 #52956MikGuest
Check the MAP versions of
AC 11, handoverControl,is set to version 3 on MSCs
AC 14, infoRetrieval, set to version 3 on MSCs & HLRs30th June 2008 at 05:26 #52957HO from WCDMA to GSM faiureGuest
Thanks for the response but I would like generally the reason for the HO failure from one way WCDMA to GSM1st July 2008 at 07:56 #52958MeyramGuest
can anyone help me where can I get whole information on 3G (features, what kind of equipments are required,
whole software conception…etc.
Thanks in advance.3rd July 2008 at 08:29 #52959GitGuest
First of all 3g to 2g neighbour, the database should be defined in MSS, RNC.
in MSS, the external LAC, MSCID of 2G neighbour should be defined.
in RNC, the information about 2G (like LAC-CI, bcch no, bsic, etc) should consisten with real 2G database.5th July 2008 at 05:56 #52960HO from WCDMA to GSM faiureGuest
thanks for the response
But i would like to know the reason related to protocol between 2G and 3G not the data base .18th August 2008 at 05:59 #52961ChathuraGuest
I’ve listed down some Common reasons for 3G-2G handover failures
1). Improper neighbour definition-this can be verified from SIB 11 message
2). Wrong settings for event 2D thresholds & TTT (time to trigger values)
3). Wrong Settings for event 3A (thresholds & TTT)
4.) Inaccurate Timer settings (eg for T309 it is recommended to have more than 5s)
above are related to wrong configurations, remember that there could be other reasons as well
furthermore if we consider the different phases of the HO process, followings can be identified as some of the reasons for failures;
1. failures During Preparation phase (eg- due to no radio resources in target cell)-these are generally called as “CS-iRAT-HO_Failure_1”
2. failures in IuB & generally called as “CS-iRAT-HO_Failure_2”
3. Due to NBAP link failures