HANDOVER TYPE
Handover per carrier
Service providers can modify as per requirement
1. HoEvent A3-Event A3 is used for both inter and intra frequency handover .Where neighboring cell has to be offset better than the serving cell for a defined time mentioned by the parameter "time to trigger " .If a hysteresis value is defined then the neighbor cell has to be offset+hysteresis better than the serving cell. Hysteresis is a value used to avoid unnecessary triggering of measurement reports when the signal is fluctuating .Using Hysteresis is optional.
2. HoEvent A4-Signal of serving cell is poor and UE starts to make measurement with A2 to find better neighbor cell, if the serving cell signal is getting better and stays stable during Time to Trigger then the UE stops measurement with A1. If it is not getting better during the Time to Trigger then it will make handover with A4 if neighbor cell is better than the threshold specified (A4 THRESHOLD_RSRP/A4 THRERSHOLD_RSRQ).The dotted line in the figure below marks the threshold.
3. HoEvent A5 -Event A5 is ideally used when carrying out an inter frequency handover for FTP DL (Non Guaranteed Bit Rate)from lower *priority band to higher *priority band. UE has to switch to the target cell and perform the signal quality measurement and come back to the current cell in cases of inter frequency.
(*Note:Priority is assigned to each frequency band depending upon the Bandwidth. Higher frequencies usually have higher priority assigned considering they have higher Bandwidth)
Handover per carrier
Service providers can modify as per requirement
1. HoEvent A3-Event A3 is used for both inter and intra frequency handover .Where neighboring cell has to be offset better than the serving cell for a defined time mentioned by the parameter "time to trigger " .If a hysteresis value is defined then the neighbor cell has to be offset+hysteresis better than the serving cell. Hysteresis is a value used to avoid unnecessary triggering of measurement reports when the signal is fluctuating .Using Hysteresis is optional.
2. HoEvent A4-Signal of serving cell is poor and UE starts to make measurement with A2 to find better neighbor cell, if the serving cell signal is getting better and stays stable during Time to Trigger then the UE stops measurement with A1. If it is not getting better during the Time to Trigger then it will make handover with A4 if neighbor cell is better than the threshold specified (A4 THRESHOLD_RSRP/A4 THRERSHOLD_RSRQ).The dotted line in the figure below marks the threshold.
(*Note:Priority is assigned to each frequency band depending upon the Bandwidth. Higher frequencies usually have higher priority assigned considering they have higher Bandwidth)
|
This parameter is the timeToTrigger value for the Event . The timeToTrigger is the time which should be satisfied for the UE to trigger the measurement report.Below we have 2 sample settings
1.Settings : 256ms ( To trigger all events.)
1.Settings : 256ms ( To trigger all events.)
480 ms (480 ms is used typically to trigger Event A4 )
2.Settings : 256ms (for most events)
40 ms(for VOLTE services in event A3 )
480 ms (480 ms is used typically to trigger Event A4 )
Values are subject to change according to the KPI results.480 ms (480 ms is used typically to trigger Event A4 )
| TRIGGER_QUANTITY |
This parameter is used to set up the TriggerQuantity of an Event during reporting neighboring cell's configuration. The TRIGGER_QUANTITY can be set to rsrp/rsrq. A UE transmits an event when RSRP or RSRQ meets a specific threshold according to TRIGGER_QUANTITY.
1.rsrp: It indicates that RSRP is used for triggerQuantity.
2.rsrq: It indicates that RSRQ is used for triggerQuantity.
3.followA2event: It indicates that the value of TriggerQuantity corresponds with the value of A2 Event triggerQuantity.
4.both: It indicates that RSRP and RSRQ are used for triggerQuantity
Samples of settings that could be used for a cell in an LTE network
Settings for Trigger Quantity(the new Release-sample)
1.Network providers could use trigger quantity "both"since the new
release for 2300 MHz intra frequency and inter frequency handover(where source
is 2300MHz to any other band )in FTP DL.
(2300Mhz band has the maximum bandwidth among other bands we want users to be in this band )
(2300Mhz band has the maximum bandwidth among other bands we want users to be in this band )
2.Handover for VOLTE (Guaranteed Bit rate service)inter and intra frequency could be done using Event A3 and it has trigger quantity "rsrp"
3.Handover for FTP DL (Non Guaranteed Bit Rate Service)inter frequency handover (Event A3)could use trigger quantity "rsrp"
4.Handover for FTP DL (Non GBR Service)intra frequency handover (Event A3) could use
trigger quantity "rsrq"
5.Handover for FTP DL(Non GBR) i.e handover from lower band to higher band could be
done using Event A5 and it has its trigger quantity "rsrq".
sameAsTriggerQuantity: If it is set to sameAsTriggerQuantity, the UE transmits only the result corresponding to the TRIGGER_QUANTITY
both: A UE transmits both RSRP/RSRQ if the REPORT_QUANTITY is set to both for the measurement result
This value can be set to both since the new release.
old releases could have sameAsTriggerQuantity
Figure 4.Sample Multicarrier Settings
A1_THRESHOLD_RSRP
|
Event A1 occurs when serving becomes better than threshold.
This parameter is set to a value between 0-97
The actual RSRP measurement in dBm can be calculated as follows
A1_THRESHOLD_RSRP-140 (dBm).
A1_THRESHOLD_RSRQ
This parameter is the RSRQ threshold for Event A1 which is used to perform measurement gap deactivation which means user equipment will not search for measurements if its serving RSRQ is better than the value specified in A1
This parameter is set to a value between integer values 0-34
The actual RSRQ measurement in dB can be calculated as follows A1_THRESHOLD_RSRQ-40/2 (dB).
A2_THRESHOLD_RSRP
A3_OFFSET
RSRP threshold used for triggering the measurement report for Event A3 to the eNB
Event A3 occurs when Neighbor becomes offset better than serving.In the network if the neighboring cell is offset better than the serving cell the event A3 occurs
The actual offset value in dB can be calculated as follows Integer Value*0.5 =Value in dB
When eNB receives a measurement report including Event A3 from UE, eNB triggers LTE handover to the best cell indicated in the measurement report. Because handover target cell is decided by UE's measurement results for neighboring cells.
Event A3 is used for LTE Intra-Frequency handover. This event type can also be used for Inter-Frequency handover and it is configurable in eNodeB side to choose the event type for Inter-Frequency
A1_THRESHOLD_RSRP-140 (dBm).
A1_THRESHOLD_RSRQ
This parameter is the RSRQ threshold for Event A1 which is used to perform measurement gap deactivation which means user equipment will not search for measurements if its serving RSRQ is better than the value specified in A1
This parameter is set to a value between integer values 0-34
The actual RSRQ measurement in dB can be calculated as follows A1_THRESHOLD_RSRQ-40/2 (dB).
A2_THRESHOLD_RSRP
Measurement is carried out by an event A2 that means the quality of the serving cell's DL reference signal becomes worse than the absolute threshold.
The higher the parameter is, measurement gap is activated for a stronger signal strength and too frequent measurement gap activation can impact service experience.
The lower the parameter is, the weaker signal strength measurement gap is activated and the later measurement gap activation can impact HO success rate.
The values in A2 is usually A1+5db .
A3_OFFSET
RSRP threshold used for triggering the measurement report for Event A3 to the eNB
Event A3 occurs when Neighbor becomes offset better than serving.In the network if the neighboring cell is offset better than the serving cell the event A3 occurs
The actual offset value in dB can be calculated as follows Integer Value*0.5 =Value in dB
When eNB receives a measurement report including Event A3 from UE, eNB triggers LTE handover to the best cell indicated in the measurement report. Because handover target cell is decided by UE's measurement results for neighboring cells.
Event A3 is used for LTE Intra-Frequency handover. This event type can also be used for Inter-Frequency handover and it is configurable in eNodeB side to choose the event type for Inter-Frequency
The higher the value of A3 offset the more we drag the calls to neighboring cells.This is very useful where we have coverage holes.The smaller the value of A3 offset the faster we release the calls to neighboring cells .This is very useful in those scenarios where a large number of LTE cells exist in a given geographical area.
A3_OFFSET_FOR_RSRQ
RSRQ threshold used for triggering the LTE neighboring cell's measurement report for Event A3.
The actual offset value in dB can be calculated as follows Integer Value*0.5 =Value in dB
Example from the Multicarrier settings shared in figure 4
For triggering handover neighboring intra frequency cell has to have an RSRQ value 3dB better than the serving RSRQ during FTP DL services
A4 THRESHOLD_RSRP/A4 THRESHOLD_RSRQ
Triggers when a neighboring cell becomes better than threshold as specified for event A4
This event type could be used for inter frequency handover and it comes after event A2.
Sample Settings:
The A4 THRESHOLD_RSRP could be set to -105 dBm
and the A4 THRESHOLD_RSRQ could be set to -4dB
However Handover_type has to be set to A4 for using this type of handover and the parameter called
Trigger_quantity rsrp or rsrq will determine if A4 THRESHOLD_RSRP or A4 THRESHOLD_RSRQ will be used as threshold
The actual offset value in dB can be calculated as follows Integer Value*0.5 =Value in dB
Example from the Multicarrier settings shared in figure 4
For triggering handover neighboring intra frequency cell has to have an RSRQ value 3dB better than the serving RSRQ during FTP DL services
A4 THRESHOLD_RSRP/A4 THRESHOLD_RSRQ
Triggers when a neighboring cell becomes better than threshold as specified for event A4
This event type could be used for inter frequency handover and it comes after event A2.
Sample Settings:
The A4 THRESHOLD_RSRP could be set to -105 dBm
and the A4 THRESHOLD_RSRQ could be set to -4dB
However Handover_type has to be set to A4 for using this type of handover and the parameter called
Trigger_quantity rsrp or rsrq will determine if A4 THRESHOLD_RSRP or A4 THRESHOLD_RSRQ will be used as threshold
A5_THRESHOLD1_RSRP & A5_THRESHOLD2_RSRP
Event A5 is triggered when the serving becomes worse than the threshold1 and neighbor becomes better than threshold 2
The A5_Threshold1 and A5_Threshold2 value of Event A5 is used during reporting measurement configurations of the neighboring LTE cells.
Its range is 0-97.(Calculation is as follows :Integer Value-140)
Typically handover for FTP DL in event A5(which is used for handover from lower band to higher band) using trigger quantity "rsrp"
Typically handover for FTP DL in event A5(which is used for handover from lower band to higher band) using trigger quantity "rsrp"
A5_THRESHOLD1_RSRQ & A5_THRESHOLD2_RSRQ
It is set to 0-34. (Calculation is as follows :Integer Value-40/2)
It is set to 0-34. (Calculation is as follows :Integer Value-40/2)
Typically handover for FTP DL in event A5(which is used for handover from lower band to higher band) using trigger quantity "rsrq"
No comments:
Post a Comment