- This topic has 25 replies, 1 voice, and was last updated 12 years, 6 months ago by Manh.
9th July 2007 at 05:57 #48101akefaGuest
Any body tell me what is incorrect in my idea regarding the half rate traffic (NAMR)
There is 10 time slots
with 70% Half rate, we will get the following:
3 full rate time slots
14 half rate time slots
in NAMR, the 3 full rate time slots will be assigned to the users untill being all dedicated. Then the other 14 time slots will start being loaded.
that means for the above example, and when the capacity is fully utilized, I should see half rate traffic (14 time slots) more than the full rate traffic (3 time slots) but this is not the fact. In statistic, I see full rate traffic always more !
Note: ericcsson9th July 2007 at 06:17 #48102PixGuest
Are you sure it works this way ? I think the 70% corresponds to the load limit at which the calls are being established in HR.
For instance, if this threshold is set to 70% :
from 0% to 70% of TCH load (number of busy TCH / total number of TCH), calls are setup in FR.
If the load is greater, then the new calls are established in HR.
When the TCH load goes below another threshold (usually 30% or 40%), the calls are established in FR again.
Maybe i’m wrong for ericsson, though…? They implemented it in a special way ?
You can try to decrease 70% to 40%; and see what is the effect on the ration HR/FR.9th July 2007 at 09:11 #48103akefaGuest
Hi Pix how are you?
HR=70%, this is the percentage of the idle tch. Once this percentage become less, the half rate time slots will work.
We can avoid the confusion by saying that we have 10 rooms (time slots) in a hotel (TRU). The first three subscribers will be given a whole room for each. Any additional subscribers will be given 1/2 room (two people in one room).
The capacity of the Hotel, therefore is 14 subscribers
3 living alone
14 living in pairs
therefore, the HR traffic should be more !
Half rate traffic = people living in sharing rooms.
But in the statistic, the full is always more ! even if there is congestion (whole capacity is utilized)9th July 2007 at 20:00 #48104PixGuest
Thx for the great explanation 😀 So who’s paying the hotel bill in the end ?
So if your threshold definition is correct, then let’s see at it differently : you can check your traffic load calculation speed. By the time the system detects more than 30% of FR utilization (3 ts used for FR, in your example), the actual cell load is already more than 70% … ?
So have a look to the traffic load averaging windows… who knows ?
Other than that, there must be a problem somewhere. You’re probably missing out something : BSC capacity is enough ? other thresholds somewhere ?
what about the limit threshold to stop the usage of HR, and setup the new calls in FR ?
pix10th July 2007 at 06:13 #48105PixGuest
I was also thinking about incoming HO : is it possible that incoming HO remain in FR ? That would explain…11th July 2007 at 17:17 #48106Da ArchitectGuest
I haven’t faced FR traffic more than HR in case DTHNAMR = 70% (E//) or in case THR_FR_LOAD_L_SV1 = 30%THR_FR_LOAD_L_SV3 = 30% (alcatel). But i have few cells with DTHNAMR = 100% and still carry FR Traffic. Therefore I thought of PIX last suggestion that is Incoming HO remains FR. I would really appreciate if someone can explain why incoming HO doesn’t change to HR in case target cell has DTHNAMR = 100% (Ericsson)or THR_FR_LOAD_L_SV = 0% (alcatel).
many thanks,11th July 2007 at 20:25 #48107PixGuest
well, in alcatel system, it is related to the cell parameter “KEEP CODEC”… i don’t know for ericsson.12th July 2007 at 08:12 #48108JehadGuest
We should understand one thing, in Ericsson system there is two parameters work as trigger point when the cell will start carrying HR traffic.
– DTHNAMR ..for NON AMR calls.
– DTHAMR..for AMR calls only.
So, if you set DTHNAMR to 70% for example, this means that when the load on the cell reach more than 70%, the HR traffic will start, mean any new call will be on HR not FR. As sson as the percenatge of IDLE TCH time slots is less than or equal 70% all the traffic on the cell will be on FR not HR.
I suggest to you check the busy hour traffic for the cell and check the traffic hourly on the cell, you will see sure the peak hour is not much so the majority of the traffic will be on FR.
Hope this can help all.12th July 2007 at 11:22 #48109akefaGuest
Jehad, your definition of the NAMRHR is reversed. Plz look at my second answere in this topic :). Furthermore, I said the cell is congested which means i am talking about the peak traffic hour.
Pix & Da Architect,
I am suspecting that the capacity limit of the BSC is the reason. thanx pix to remind me what i should remember all the time ! I will check this issue.
In fact I am interested in the case of 100% HR in which FR traffic survive. if we want to be sure that the incoming HOs are the source of the full rate traffic, Da Architect I suggested for you to make a table of two coloms: incoming handover and full-rate traffic to see if thier values increase and decrease togather 🙂 let us know13th July 2007 at 11:52 #48110Da ArchitectGuest
Accompanied to your value suggesiton, i will conduct a drive test scenario in E// cells to realize reason behind this FR traffic.14th July 2007 at 20:06 #48111Da ArchitectGuest
in Alcatel, if parameter [KEEP_CODEC_HO = free choice of the codec]; what would be the BSC desicsion for incoming HO to a target cell that has THR_FR_LOAD_L_SV1 = THR_FR_LOAD_L_SV3 = 0%
Is there a similar parameter in Ericsson?15th July 2007 at 18:14 #48112pixGuest
you need to set the THR_FR_LOAD_U_SVi as well.
If they’re all at 0%, the cell will only carry HR calls, at any time of the day, and incoming HO with KEEP CODEC HO FREE will be allocated as HR.
Well, that’s what’s written in the doc, i never tried it on the field.
I’m sorry if my question is too personal, but in which country are you working in ?16th July 2007 at 20:47 #48113Da ArchitectGuest
ofcourse, I know that i have to modify the upper threshold too. but i didn’t know about the keep_ho_codec action in case it was set to free.
Recently I work in Africa in the systems(3G/EDGE/GPRS/2G) for the two platforms (Alcatel + Ericsson)6th February 2008 at 12:53 #48114LotfiGuest
can you please tell me if BCCH, SDCCH , Dynamic SDCCH and reserved data Time Slots are taken into account in the calculation of the cell load : [load = NB_BUSY_TS / NB_TS ]
I’m speaking about Alcatel BSS
Thanks 🙂6th February 2008 at 15:38 #48115mehrdadGuest
Ericsson document tell us:
In general the following cases occur:
If the MS and the cell support AMR HR and the number of idle FR TCH:s divided by the total number of de-blocked FR TCH:s is equal or above DTHAMR FR TCH:s will have precedence over HR TCH:s. If the number of idle FR TCH:s divided by the total number of de-blocked FR TCH:s is less than DTHAMR HR TCH:s will have precedence over FR TCH:s
If the MS or the cell do not support AMR HR and the number of idle FR TCH:s divided by the total number of de-blocked FR TCH:s is equal or above DTHNAMR FR TCH:s will have precedence over HR TCH:s. If the number of idle FR TCH:s divided by the total number of de-blocked FR TCH:s is less than DTHNAMR HR TCH:s will have precedence over FR TCH:s
so if your threshold for DTHNAMR be 70% so the traffic will start with FR channel.
4 TRXs (1 BCCH & 2 SDCCHs & 29 TCHs)
%70 * 29 = 21
the BSC assigns FR channel in the begining until 8th channel assignment, for 9th MS assigning HR channel will be start.
1- some MSs can not support HR, so BSC assigns FR channel to them.
2- sometimes incoming HO parameters forces BSC to assign FR channel to MS.
Hi pix, Ericsson has only 1 threshold for Half Rate. Nokia has 2 threshold (FRL and FRU) for Half Rate (Hysteresis).
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