Question: GSM Trafiic balancing

[beniy]

Dear Experts,

I have a case which I should offload one cell and balance its traffic to other cells.
* I have not permission to change Azimuth and Tilt.

I can Just change parameters.

All the cells are Consentric.

Which Handover parameters can help? and etc.

Thanks so much for your help,
I will add thanks and rep to all answer.

[dekili]

How about the power? Could you change TX power and force users to associate with the target BTS instead of the one that they connect now? I gues it would be the easier thing to do. You have probably already tried something like this but just to mention. Could you give us more details?

[pathloss]

Maybe you should search for "Traffic-triggered Handover".

"It is possible to predefine a certain traffic level for a cell to start handing over calls to adjacent cells, and thereby offload the cell. This can be very useful for cells that have periodic hot-spot traffic, and might save the expense of deploying extra capacity for servicing only the occasionally peak load. However this is only possible if the adjacent cells are able to service the traffic at the expected quality level."

[tsiz]

Dear Experts,

I have a case which I should offload one cell and balance its traffic to other cells.
* I have not permission to change Azimuth and Tilt.

I can Just change parameters.

All the cells are Consentric.

Which Handover parameters can help? and etc.

Thanks so much for your help,
I will add thanks and rep to all answer.

You can change the handover offsets between source and target. You can also use cell load sharing to offset traffic. CLSLevel and CLSacc parameters. You can also use Layer, Layerhyst and LayerThr to offload traffic from one sector to another.

[pathloss]

Dear beniy,

One question that I have, is it just this sector, which has alot of load on all your cells? Or is it just the Inner- (1800) or Outer- (900) Cell which has bigger load?

[beniy]

How about the power? Could you change TX power and force users to associate with the target BTS instead of the one that they connect now? I gues it would be the easier thing to do. You have probably already tried something like this but just to mention. Could you give us more details?

Yes, I can change power but not much..
Be cause operator do not let me change it high.
These cells are near to each other (near 2 Km distance)
Please describe more.
Thanks

[beniy]

Maybe you should search for "Traffic-triggered Handover".

"It is possible to predefine a certain traffic level for a cell to start handing over calls to adjacent cells, and thereby offload the cell. This can be very useful for cells that have periodic hot-spot traffic, and might save the expense of deploying extra capacity for servicing only the occasionally peak load. However this is only possible if the adjacent cells are able to service the traffic at the expected quality level."

Could you please describe more??
Vendor is Huawei.
what do you mean "It is possible to predefine a certain traffic level for a cell to start handing over calls to adjacent cells"
Is there any parameter for that?

[beniy]

You can change the handover offsets between source and target. You can also use cell load sharing to offset traffic. CLSLevel and CLSacc parameters. You can also use Layer, Layerhyst and LayerThr to offload traffic from one sector to another.

Dear tsiz,
The vendor is Huawei.
We have not some parameters like CLS.
Do you know anything like that in Huawei??
What do you mean use "layer"??
Please describe more might be I can find them in Huawei

[beniy]

Dear beniy,

One question that I have, is it just this sector, which has alot of load on all your cells? Or is it just the Inner- (1800) or Outer- (900) Cell which has bigger load?
Hi Pathloss,

No this cell has high congestion and we cannot expand untill 3 months later.

This is common BCCH (Consentric) which all 900 and 800 have high traffic.
Please help if you have any idea!!

[Tariq]

Have u tried to change Handover Offsets of both cells, that might be very useful

[electron]

Dear Experts,

I have a case which I should offload one cell and balance its traffic to other cells.
* I have not permission to change Azimuth and Tilt.

I can Just change parameters.

All the cells are Consentric.

Which Handover parameters can help? and etc.

Thanks so much for your help,
I will add thanks and rep to all answer.


Are they belongs to same band?

Which strategy you are using ? Multi band or dual band?


Changing HO border is different than traffic sharing Which vendor you are using?

[pathloss]

Hi Pathloss,

No this cell has high congestion and we cannot expand untill 3 months later.

This is common BCCH (Consentric) which all 900 and 800 have high traffic.
Please help if you have any idea!!

Okey, as I understood.. your options are limited, no tilt and power changes..

So only thing I know, is Traffic HO. (Inter-cell Handover due to BSS Resource Management Criteria (Traffic HO))

This is from NSN BR.9 Document, as I don't know Huawei. Have a look at your vendor parameter description.

[dekili]

Yes, I can change power but not much..
Be cause operator do not let me change it high.
These cells are near to each other (near 2 Km distance)
Please describe more.
Thanks

Since you don't have "Traffic-triggered Handover" parameter, you can't change azimuth and elevation, I thought that you might try to simulate "Traffic-triggered Handover" by making TX power up for the sector that is not having too high traffic and to lower power on the site that is having that high traffic to serve. If your users are not "flying around" in that area and act more static, this could help since the part of the hot spot could be covered by BTS with lower traffic volume...
Sorry, nothing else comes to my mind...

[m121]

I don't know how far you are with this problem but as far as I know there are some solutions to ease congestion from customer point of view:
a) How about HR and FR, are all calls in HR at peak hour?If no try forcing them to HR at peak hour
b) How about Queuing? Is it enabled? If no definitely enable it.
c) How about Directed retry? If not enabled definitely enable it and ease DR to closest not congested cell (for other cells 6dB margin, for closest 0)
d)Ease PBGT HO to closest not congested cell, Rx access minimum let's say -90dBm but HO Margin -6dB or even higher. So HO will be triggered to CellB even if it's worse than Cell A but with RxAcMin you will be shore that call isn't dropped.

Best solution is combination of all four. A and D will ease congestion itself, B and C will ease congestion effects.

[Tariq]

I hope this doc will be of some help it describes the cell selection re-selection parameters of Huawei in GSM

[beniy]

I don't know how far you are with this problem but as far as I know there are some solutions to ease congestion from customer point of view:
a) How about HR and FR, are all calls in HR at peak hour?If no try forcing them to HR at peak hour
b) How about Queuing? Is it enabled? If no definitely enable it.
c) How about Directed retry? If not enabled definitely enable it and ease DR to closest not congested cell (for other cells 6dB margin, for closest 0)
d)Ease PBGT HO to closest not congested cell, Rx access minimum let's say -90dBm but HO Margin -6dB or even higher. So HO will be triggered to CellB even if it's worse than Cell A but with RxAcMin you will be shore that call isn't dropped.

Best solution is combination of all four. A and D will ease congestion itself, B and C will ease congestion effects.
Thanks so much.
a) HR usage is more than 97%
b) what is Queuing?
Have we got that in Huawei??
c)DR is enable. But I have not any information about the related parameters to DR.Please more describe.how can I ease to closest?
what do you mean (for other cells 6dB margin, for closest 0)??
d)could you please more describe about this strategy?
I mean for neighbour and cogested cell (the margins).
Thanks again.

[m121]

I am not familiar with Huawei so I can't give you exact parameters but I will try to describe how it works in exSiemens.

Queuing is basic feature that puts MS in SDCCH phase in "waiting list". If cell is congested and Directed retry didn't find suitable cell, MS is put in Que for time up to 8 seconds (you can define it manually at BSC level) at SDCCH to wait for TCH to free up before disconnecting call with "No TCH available". This is basic feature and it should be available in Huawei.
Regarding Directed Retry(DR): At least in Siemens you can define on ADJC level a handover margin for DR. Default is 6db so Cell B must be at least 6db stronger than serving cell to be as target for DR. So you must change it to 0db for ADJC to cell where you want the traffic to go if Cell A is congested.
Regarding HO margins:
Strategy is very simple, for ADJC to Cell B where the traffic should go, put Handover margin in negative values (by default all cells have positive HO margins to avoid Ping-pongs from happening) but Rx minimal values at what Cell B is suited as target, at beginning put at higher values to avoid call drops after handover.
Put it in example:
Cell A is serving to you at -85dBm. MS reports Cell B with -90dBm. In normal conditions HO is not happening. Now put HO margin for CellA-CellB ADJC at -6db. Now call is handovered to Cell B because Cell B is worse only by -5db.

I hope it helps.

[dNoB]

Dear Experts,

I have a case which I should offload one cell and balance its traffic to other cells.
* I have not permission to change Azimuth and Tilt.

I can Just change parameters.

All the cells are Consentric.

Which Handover parameters can help? and etc.

Thanks so much for your help,
I will add thanks and rep to all answer.

... if i remember right, there are documents on Huawei here re
access problem optimization
handover and call drops
...
1) start controlling from access optimization first... and see what happens in traffic stats.
2) if you are not satisfied with the results, start controlling the handovers... and see what happens.

[rimoucha]

Hello,

To relieve congestion you can:

1/Activate HR.
2/Activate Load HO on the congested cells.
3/Use a more strict RXLEV_ACCESS_MIN Value (I mean a higher value for example -106 instead of the default -110) at the congested cells (but with the risk of creating some coverage holes)
4/Use a lower CRO value at the congested cells,this will favor the neighbouring cells in Idle mode reselection


Best regards,

[evagtf@yahoo.fr]

Have u possibility to make TRX traffic from full to dual rate?

evagtf