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Re: FACH Congestion Optimization
Agenov,
I don't know in Huawei Network but in E/// according the vendor we will just have URA_PCH + Fast Dormancy Handling working 100% in W13B.
In E/// you put more users in FACH State when you set URA References per cell this means activate URA_PCH. This happens cause if you check state transitions you will see 2 new transitions from and to FACH.
If you activate Fast Dormancy Handling you put less users in FACH cause you can send UEs directly from CELL_DCH to URA_PCH, the problem here is pre release 8 UEs can have baseband restart and for this reason E/// has a parameter state128..... that you have to set TRUE to avoid these restarts but there is a problem here...
When you activate it all UEs will just follow the same way CELL_DCH -> FACH -> URA_PCH and this disable the real benefit of Fast Dormancy Handling.
In W13B there is a feature that works with pre release 8 UEs enabling the real Fast Dormancy Handling that supports (CELL_DCH->URA_PCH) and avoiding baseband restarts in UEs that not supports this transition, there is also now in W13A a new feature that E/// is testing that enables the transition URA_PCH->CELL_DCH.
For E/// then of you have W13B you are able to activate new transitions that can offload CELL_FACH. Also to avoid FACH overload you can set agressive Channel Switching strategies making transitions faster from and to CELL_FACH avoiding overload this channel. Just make sure your RNC supports the MP LOAD and DC LOAD increasing cause agressive strategies increases RNC LOAD, tests that I have done here increased up to 5% of load.
For E/// then Fast Dormancy Handling do not overload FACH if it is really working properly what overload FACH in true is URA_PCH state active, of course URA_PCH is really important to reduce RNC MP and DC LOAD but you have to check the items below:
FACH Overload:
1) Try to balance the load with another carrier, deploy second or third carrier if have conditions for it.
2) If your RNC have conditions set agressive Channel Switching strategies.
3) Just activate URA_PCH if your RNC really needs but try to activate Fast Dormancy Handling really working as the theory (I don't know if another vendor has the same issue)
4) Check if is available the new transition URA_PCH -> CELL_DCH ans acivate it.
Just talking about item 3 there is a important thing to comment, URA_PCH is really necessary if you already have LTE in your network cause fisrt Software Versions of LTE just allows the cell reselection to LTE if the UEs is in IDLE or URA_PCH and if don't have URA_PCH with Fast Dormancy Handling working well in your network rarely Smartphones goes do IDLE (because background apps running all the time).
New versions as enabling reselection in FACH, enabling Handovers, etc.
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