Blind handover
The blind HO aims to an alternative frequency within the same network
(e.g. LTE to LTE) or to an alternative technology (e.g LTE to WCDMA).
Not only the HO but also the R-w-R (Release with Redirect) procedure can be Blind.
"Blind" as opposed to "Measurement Based". The meaning of blind HO/R-w-R is:
"without prior knowledge (measurements) of the quality or power level of the alternative target frequency or the alternative technology network (in case of IRAT)".
By no means it suggests that the HO is triggered without thresholds being crossed as it is often wrongly perceived. Instead it is triggered based on an A2 event (coverage triggered HO) of the serving cell.
The term "blind" refers to the fact that the alternative frequency/RAT will be selected and enforced without any measurements on it prior to the decision, i.e. no A5/B2 events will be configured on the UE for the alternative frequency/RAT.
The blind HO is a risk that we take since we don't know the radio characteristics of the target frequency/RAT we are moving to, therefore it is recommended to be configured only for alternative frequencies where we have sufficient overlap between the source and the target cell.
However the risk can be suppressed by careful cell planning and coverage estimation from cell planner's simulation tools, so we guarantee the quality/signal strength by well performed Radio Design!
The trade off is that it can be fast and simple since no additional ad-hoc measurements (A5,B2 A1) have to be configured on the UE. And it can also tackle the case where the UE has no capabilities to measure the alternative frequency.
In LTE in case of a UE with at least one voice bearer the blind HO is not an option. Despite the low coverage it is preferable for the UE to stick to the original frequency.
(e.g. LTE to LTE) or to an alternative technology (e.g LTE to WCDMA).
Not only the HO but also the R-w-R (Release with Redirect) procedure can be Blind.
"Blind" as opposed to "Measurement Based". The meaning of blind HO/R-w-R is:
"without prior knowledge (measurements) of the quality or power level of the alternative target frequency or the alternative technology network (in case of IRAT)".
By no means it suggests that the HO is triggered without thresholds being crossed as it is often wrongly perceived. Instead it is triggered based on an A2 event (coverage triggered HO) of the serving cell.
The term "blind" refers to the fact that the alternative frequency/RAT will be selected and enforced without any measurements on it prior to the decision, i.e. no A5/B2 events will be configured on the UE for the alternative frequency/RAT.
The blind HO is a risk that we take since we don't know the radio characteristics of the target frequency/RAT we are moving to, therefore it is recommended to be configured only for alternative frequencies where we have sufficient overlap between the source and the target cell.
However the risk can be suppressed by careful cell planning and coverage estimation from cell planner's simulation tools, so we guarantee the quality/signal strength by well performed Radio Design!
The trade off is that it can be fast and simple since no additional ad-hoc measurements (A5,B2 A1) have to be configured on the UE. And it can also tackle the case where the UE has no capabilities to measure the alternative frequency.
In LTE in case of a UE with at least one voice bearer the blind HO is not an option. Despite the low coverage it is preferable for the UE to stick to the original frequency.
Comments
"when performing the handover procedure, as specified in 5.3.5.4, ensure that a measObjectId corresponding to each handover target serving frequency is configured as a result of the procedures described in this sub-clause and in 5.3.5.4;"
In case of blind handover, UE obviously doesn't have the measObjectId related to target frequency. If I ensure that measObjectId of target frequency is configured before starting handover then blind handover won't be possible.
I am trying figure out what that line actually means. Any idea?