Difference between B1 and B2 events

[Bohemian]

Dears,
Why B1 event is there although B2 can do IRAT triggering? What B1 does basically and how it differs from B2?

[auto_art]

I would use B1 for optimizing Irat spillage, may be not able to use B2 for that.

remember events helps us knowing the system behavior, they are not for only triggering HO. this is purely my understanding.

[Bohemian]

@auto_art: thanks for your response.
I am unsure about what you meant to say. can you clarify with numerical value(s) and explain a bit more about B1 please?

[wolverine]

B1 only looks at the quality of the target system.
B2 looks at the quality of the source system AND the quality of the target system

So typically for mobility you would use B2 as you only want to leave 4G if 4G is poor AND 3G/2G is good.

B1 is used for functionality where the quality of the source system is not important. So for example measurement based CSFB or load balancing between 4G and 3G.

[Bohemian]

@wolverine and other: can we also say that B1 helps in SRVCC too?

[omarGSMUMTS]

Event B1 (Inter RAT neighbour becomes better than threshold)The UE shall:
1> for UTRA and CDMA2000, only trigger the event for cells included in the corresponding measurement object;
1> consider the entering condition for this event to be satisfied when condition B1-1, as specified below, is fulfilled;
1> consider the leaving condition for this event to be satisfied when condition B1-2, as specified below, is fulfilled;
Inequality B1-1 (Entering condition)
Mn + Ofn - Hys > Thresh
Inequality B1-2 (Leaving condition)
Mn + Ofn + Hys < Thresh
The variables in the formula are defined as follows:
Mn is the measurement result of the inter-RAT neighbour cell, not taking into account any offsets.
Ofn is the frequency specific offset of the frequency of the inter-RAT neighbour cell (i.e. offsetFreq as defined
within the measObject corresponding to the frequency of the neighbour inter-RAT cell).
Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigInterRAT for this event).


vent B2 (Serving becomes worse than threshold1 and inter RAT neighbour becomes better than threshold2) The UE shall: 1> for UTRA and CDMA2000, only trigger the event for cells included in the corresponding measurement object;1> consider the entering condition for this event to be satisfied when both condition B2-1 and condition B2-2, asspecified below, are fulfilled; 1> consider the leaving...