Congestion in WCDMA RAN

[verist3]

Tks for the link bos..
i have added reputations and thanks..

[electron]

Hi ,


There is a subject in WCDMA which named capacity management which is divided to:

1.Admission Control

2.Congestion Control

If you refer to your vendor WCDMA Functionality documents the algorithm and related parameter and timers are explained there .


If any more information is needed just give a hence!


Thanks,
Reza

[songyan05]

RN Admission Control:
When new resources are needed for a radio connection, the RN Admission Control function receives a request for admission. The request specifies the estimated amount of system resources that the radio connection needs. The request is evaluated by one or more admission policies. A response is sent out to grant or deny the new resource request.

RN Admission Control has different policies judging for each resource whether a request can be admitted or should be rejected. If no resources are available, the RN Soft Congestion functionality may free resources of existing radio connections and thereby enable the request.

Each admission policy monitors the resource against an Admission Level and a Max Level.

Up till the Admission Level, the request is admitted
Between the Admission and Max Level, (guaranteed, non-handover) or (non-guaranteed, non-handover/handover) requests are not admitted unless RN Soft Congestion actions can find the required resources to release.
Up till the Max Level (guaranteed, handover) requests are admitted (if physical resources are available). RN Soft Congestion action is triggered, but it is not a condition for admission.

RN Congestion Control
The RN Congestion Control function detects and resolves overload situations on certain system resources. It consists of three types, UL overload, DL overload and DL HSDPA overload . Capacity Management has been updated to remove the differentiation of the guaranteed-hs connection types as separate class. As a consequence, the interactive/background PS services mapped on HS are not targeted during a DL cell congestion situation, while guaranteed services are targeted according to the guaranteed class differentiation settings.
Congestion Detection
Congestion detection is triggered by UL cell congestion, DL cell congestion and DL HSDPA congestion detection.

Uplink Cell Congestion Detection
Congestion due to radio overload in uplink is detected when the UL RWTP exceeds a certain configurable threshold for a longer time than the hysteresis time. The threshold for detection of UL congestion is determined by iFCong and the hysteresis time is determined by iFHyst.

RN Congestion Control considers UL congestion to be resolved when the uplink RTWP for a particular cell is below iFCong for a longer time than the hysteresis time iFHyst.

Downlink Cell Congestion Detection
Congestion due to radio overload in the non HS downlink transmitted carrier power is detected when the measured downlink transmitted carrier power exceeds a certain configurable threshold for a longer time than the hysteresis time. The threshold for detection of downlink congestion is determined by the parameters pwrAdm + pwrOffset and the hysteresis time pwrHyst.

Downlink cell congestion is considered to be resolved when the downlink transmitted carrier power for a particular cell is below pwrAdm + pwrOffset for a longer time than the hysteresis time.

[Mctest]

2songyan05 Tell me please,which source did you use for your post?

[dominky]

Hi guys, I'm new here and want to say hello!

My experience is for IUB cong: reduce GBR -> GBR is a reservation at the whole network and reserves the rate of GBR for each user at e.g. the IUB interface. So if you reduce GBR from e.g. 64-32kbps, the maximum user number increases by 2 times. I made this change in a Huawei network and all IUB congestion disappeared
I didn't find any drawbacks, that is because of the typical user behavior in interactive service is internetbrowsing, which is bursty traffic for a short time and after that reading for a much longer time - try it out!

For Channel Element congestion the solution was DCCC (Huawei): I changed the ulmidratethd from 128 to 64 (mbr is 144) and dcccratethd to from 64 to 32 => almost no more CE congestion! Also here is the crucial factor the user behavior. RB128 use the same amount of credits as 144, so before there was no effect by downsizing the radio bearer. For DCCCRATETHD, RB32 needs just the half of credits (I guess 3 -> 1.5CE) compared to RB64, so the useage is the double of before. My next step had been to increase the TVM thd for event 4b to downsize earlier, but was not necessary.

I hope that is usefull to you!

[tukangoptim]

perhaps attached admission control workflow give some hints..

[viswajeet]

the best way to overcome congestion is upgrading, may be tx or carrier, or license. as my experience feature or parameter can not help much.
however in 3G, another way to "save" KPI is by degrading user experience performance.

[jack_ryan]

can you upload it on 4share? i'm a new member so i can't download it. thanks so much

[dominky]

the best way to overcome congestion is upgrading, may be tx or carrier, or license. as my experience feature or parameter can not help much.
however in 3G, another way to "save" KPI is by degrading user experience performance.

I generally agree!
But you know that is connected to expenses and in my experience, the provider first try to save money with the aid of software changes - however upgrading hardware is always the best soloution.

Attached you'll find the Channel Element usage by service and related credits used.

[cococrunch]

@ Desi Larka
Here is the external link for download..
Plz say thanx to cococrunch for his sharing..


http://www.4shared.com/file/23257822...e_Upgrade.html

Thanks Paboya for your kindness to upload this for other users..

To Kadir,

The one you posted refers to the upgrade progress/sequence of WBTS that we proposed. Basically Set A is the default configuration in our network upon integration, as traffic goes higher we can upgrade to Set B and so on. We thought of this bundle because some upgrades are not effective without other upgrades, i.e. 10 codes & code multiplexing.

Any comments are welcome..