- This topic has 22 replies, 1 voice, and was last updated 8 years, 9 months ago by pix.
6th April 2011 at 20:45 #66131IanGuest
We have Microcell in our Network B10 Alcatel.
We have 80 to 85 % HO DL quality, meaning most of the hand-overs to leave the microcells are triggered in DL Qual; (HO_Level=-94)
Theese microcells are supposed to HO to Umbrella layer on level but most of HO are triggered on Qual, and there are no interferences .
I’m looking for a good set of parameters. (maybe with features MCHO)
If anybody can help, that would be great.
Ian8th April 2011 at 14:11 #66132pixGuest
what are the settings for
for your microcell ?
pix12th April 2011 at 00:09 #66133IanGuest
a_qual_ho= 4 (SACCH)
I think by applying MCHO feature, it is not taking into account other parameters, i’ve been looking for an ALU doc but cant find any. Maybe you can help.
Yann14th April 2011 at 19:25 #66134IanGuest
Do you see anyhting wrong with these parameters ?
Do you know how MCHO works with ALU ?
Ian17th April 2011 at 21:24 #66135pixGuest
yes, i do know how MCHO work 🙂
so i’m sure we will sort it out !
first thing : whn you activate the MCHO handovers, they do not forbid other type of handovers to take place. They only activate 3 new causes (UL and DL and BAD SACCH) among all the others that already exist.
IMO, the MCHO causes DL and UL are not useful and can be simulated by the typical “low DL” and “low UL” level HO causes.
The cause BAD SACCH is more interesting and is tuned thanks to the parameter N_BAD_SACCH.
1/ Deactivate MCHO DL and MCHO UL.
2/ Apply these default settings;
ho_margin(s,n) = 5dB in both directions
Optimize this setting:
a_pbgt_ho = 12, then 10 then 8 SACCH
do you see any decrease of HO QUALITY ?
What about HO INTERFERENCE ? Is it high ?
Please post some real Qos readings for HO split, HO outgoing preparation sucess rate and HO efficiency rate, idle band measurements of the interference and the “RMS” rxlev_avg, rxqual_avg, timing_advance_avg for each TRX of that cell.
pix3rd May 2011 at 20:40 #66136IanGuest
I had tried these settings and we are not doing a lot of HO qual but we are doing a lot of Ping Pong between Macro and Micro.
No Ho Interference.
Is there any way to stop Ping Pong ? i know with other vendor you can set up a Penalty for Ping Pong.
Do you have good settings using MCHO ?
Ian5th May 2011 at 14:59 #66137pixGuest
ping pong between micro and macro…
micro to macro : those are emergency handovers, so i guess your signal quality in the micro cell is very bad.
macro to micro : those are capture ho, the MS is sent to the micro cell because the rxlev of the microcell is good enough.
what is your setting of L_RXLEV_CPT_HO(macro, micro) ?
The anti ping pong timer is calle T_INHIBIT_CPT. Tune it to a high value in the macro cell (about 40s).It will prevent the capture ho from macro to micro AFTER the MS did a QUALITY HO from micro to macro.
The main issue seems to be bad quality in the microcell, perhaps your capture ho is done too early.
L_RXLEV_CPT_HO(macro, micro) ?
pix7th May 2011 at 01:52 #66138IanGuest
values are :
L_RXLEV_CPT_HO(macro, micro) ?
Micro to Macro, -85
Macro to Micro, -75
8 SACCH for Macro, 6 SACCH for Micro
Do you think these parameters correct ?
Ian7th May 2011 at 07:19 #66139pixGuest
yes, those settings are correct.
do you see a lot of quality ho in the micro cells ?
pix7th May 2011 at 16:54 #66140IanGuest
Unfortunately yes, and we are doing Ping Pong HO.
Dont know whats going on.
As Microcell, looks like all HO are tiggerred within Emergency on DL QUAL ; no pbgt, no level; does it mean all HO leaving the cell are on QUAL ?
IAn7th May 2011 at 18:40 #66141pixGuest
it seems you have a real quality problem in your microcells.
have you checked RMS ?
– rxqual avg
– rxlev avg
– timing advance average
– “s” average (radio link counter)
– UL FER
or just by doing a drive test, you’ll see where you’re having a quality issue. have you tried changing frequencies ? deactivate DL power control ? deactivate amr ?
In your situation, the t inhibit will work very well, as i explained earlier… but it is just hidding the problem, not fixing it.
pix12th February 2012 at 20:43 #66142GauravGuest
I want to know about HO parameters how do they work???
Pls suggest…….13th February 2012 at 13:24 #66143pixGuest
those are averaging windows, used to average the last “n” SACCH measurement-results.
Those averages are then used for HO decisions (= the raw measurements are useless).
If A_lev_Ho = 4, it means that the value of rxlev used in algorithms is acctually the averages of the past 4 rxlev measuremed.
There is one measurement every 480ms (= 0.5s), so it means that one avg_rxlev is an average of the past 4*0.5 = 2s.
If a_lev_ho is too small, then averages are too ‘jumpy’. HO decisions are made on fake pikes or dives .
If too large, then in front of a criticial loss of signal, the averages will not reflect the problem soon enough. The HO cannot be detected in time.
pix20th February 2012 at 21:55 #66144mannuGuest
Actually i am also working on ALU micro site and i faced one problem there is a lots of uplink quality handover happened in one of cell,actually there are two sectors in a site one is working fine and the other one has lots of uplink quality handover ,i checked frequency i checked TRX by shifting traffic one by one there is no alarm no hardware faulty but still i am not able to find the problem.
will you help me on this topic21st February 2012 at 10:34 #66145pixGuest
Since when do you have interference in UL ? Since forever ? Or since a specific date ?
When you swapped the two cells, does the problem occur on the same “physical sector” than before, or on the same “logical cell” than before ?
If same physical sector – then you have a HW issue with the micro BTS. Check feeder connection and try to make a full restart of the BTS.
If same logical cell – then you do have a configuration problem, probably due to frequencies. Could you swap frequencies from one cell to the other one?
For each cell :
* What is the HO UL Qual % in each cell ? (busy hour value)
* how much is the TCH erlang BH traffic ?
* how much is the “idle channel interference” ?
* how much is the average timing advance ? (in NPO Indicator family – Radio Measurements -)