How to shift CS traffic from 3G to 2G

[mounir34]

1. There is no similar feature as CSFB(LTE feature) on 3G side. For move CS service from 3G to 2G, 3G can only try to increase CS service handover from 3G to 2G, which means handover CS service from 3G to 2G as much as possible.
2. There’re 2 ways to increase the handover from 3G to 2G.
a) Increase Inter-RAT Handover Based on Coverage(WRFD-020303).
Adjust the threshold to make Inter-RAT measurement and execution be triggered more easily.
b) Enable Inter-RAT Handover Based on Service(WRFD-020305) for CS service.
The difference between Inter-RAT Handover Based on Service(WRFD-020305) and Inter-RAT Handover Based on Coverage(WRFD-020303) is triggering condition.
The Inter-RAT measurement of Inter-RAT Handover Based on Coverage(WRFD-020303) is triggered by 2D event, while Inter-RAT Handover Based on Service(WRFD-020305) is triggered by service type. This means, Based on Coverage(WRFD-020303) can only trigger the IRAT measurement when the signal strength is lower than 2D threshold, while Based on Service(WRFD-020305) can trigger when current service is CS service. So, if enable Based on Service(WRFD-020305), IRAT handover can be increased on the area where the signal strength are both good.


3. The other feature to move CS service to 2G side is “WRFD-020120 Service Steering and Load Sharing in RRC Connection Setup”. This feature can redirect the traffic according to the service type in RRC procedure. Cs service can be redirected from 3G side to 2G side by this feature. The negative affection is call setup establishment time may increase obviously.

thanks

[mounir34]

if you found it usful thanks to add reputition

[shishio]

make EcNo event 2D (compressed mode start) of CS services very high like -6 and EcNo event 2F (compressed mode stop) of CS services like -4, since its almost impossible to have such good EcNo values in a cell (except you are standing right next to the NodeB antenna) that means the system will assume that that you are in poor coverage and will initiate interRat HO to 2G -----this is for coverage based interRat HO.

[shishio]

make EcNo event 2D (compressed mode start) of CS services very high like -6 and EcNo event 2F (compressed mode stop) of CS services like -4, since its almost impossible to have such good EcNo values in a cell (except you are standing right next to the NodeB antenna) that means the system will assume that that you are in poor coverage and will initiate interRat HO to 2G -----this is for coverage based interRat HO.

the thresholds i mentioned earlier will shift almost all, if not all CS traffic from the 3G cell to 2G, if you intend to shift only a part of the traffic then you could play around with weaker thresholds like 2D=-10, 2F=-8

[mounir34]

yes brother usually i am using the 2D/2F threshold to shift CS or PS service to 2G, the Handover based on service is good solution to use during special event to affload the 3G Layer

the thresholds i mentioned earlier will shift almost all, if not all CS traffic from the 3G cell to 2G, if you intend to shift only a part of the traffic then you could play around with weaker thresholds like 2D=-10, 2F=-8