5. Parameters Described Within Context
5.3.4 Handover in Connected Mode (CELL_DCH) – Inter-Frequency or Inter-RAT
Ec/No and Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set. When one of the following Events occurs, the UE is commanded to either start or stop Compressed Mode (CM) measurements for either Inter-RAT or Inter-Frequency neighbors.
The UE Filters, Offsets and Weights the measurements to ensure the criteria for one of the following Events are met. If one of the criteria is met, the UE sends a MEASUREMENT REPORT to the RNC.
• Current Used Frequency is Below Threshold (Event 2d) – Begin CM
• Current Used Frequency is Above Threshold (Event 2f) – Cease CM
• UE Transmit power is Above Threshold (Event 6d) – Begin CM
• UE Transmit power is Below Threshold (Event 6b) – Cease CM
The Serving RNC then determines whether the UE makes Compressed Mode (CM) messages on Inter-Frequency or Inter-RAT neighbors based upon configurable parameters.
Lastly, upon receiving the MEASUREMENT REPORT from the UE, the Serving RNC sends a
MEASUREMENT CONTROL message to the UE with additional Event based criteria that the UE will use to evaluate its Inter-Frequency or Inter-RAT neighbors.
If hsToDchTrigger(poorQualityDetected) [RNC, 1=TRUE, Binary, Fixed] is set to 1=ON, UEs with HSDPA capability will be Down-Switched to an Interactive Packet Switched 64/64 Radio Access Bearer (RAB) for Compressed Mode measurements. If hsToDchTrigger(poorQualityDetected) [RNC, 1=TRUE, Binary, Fixed] is set to 0=OFF, HSDPA capable UEs could drop due to their not being allowed to make Compressed Mode measurements.
The following describes the triggering and evaluation mechanism involved in Frequency and Inter-RAT Handover. The Handover algorithm is the same for Speech and Interactive Packet Switched R99 Data. All Interactive Packet Switched R99 Data connections are Down-Switched to Interactive Packet Switched 64/64 to order to make Compressed Mode (CM) measurements.
5.3.4.1 Begin Compressed Mode – Current Used Frequency is Below Threshold (Event 2d) For Cells that meet the hho (section 1.7) criteria: If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) Ec/No of the Best Cell in the Active Set becomes less than the absolute threshold usedFreqThresh2dEcno(hho) [Cell, -12, dB, Fixed] - hysteresis2d [RNC, 4, 0.5 dB, Fixed] / 2, for a time equal to timeToTrigger2dEcno [RNC, 320, ms, Fixed] , or if the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set becomes less than the absolute threshold usedFreqThresh2dRscp(hho) [Cell, -106 ±4, dBm, Fixed] -
hysteresis2d [RNC, 4, 0.5 dB, Fixed] / 2, for a time equal to timeToTrigger2dRscp [RNC, 320, ms, Fixed] , then event 2d occurs. The UE then sends a MEASUREMENT REPORT message for event 2d to
the Serving Radio Network Controller (SRNC). When the Serving Radio Network Controller (SRNC) receives event 2d, it commands the UE to begin Compressed Mode measurements.
For Cells that meet the sho (section 1.7) criteria: If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) Ec/No of the Best Cell in the Active Set becomes less than the absolute threshold usedFreqThresh2dEcno(sho) [Cell, -15, dB, Fixed] - hysteresis2d [RNC, 4, 0.5 dB, Fixed] / 2, for a time equal to timeToTrigger2dEcno [RNC, 320, ms, Fixed] , or if the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set becomes less than the absolute threshold usedFreqThresh2dRscp(sho) [Cell, -112, dBm, Fixed] - hysteresis2d [RNC, 4, 0.5 dB, Fixed] / 2, for a time equal to timeToTrigger2dRscp [RNC, 320, ms, Fixed] , then event 2d occurs. The UE then sends a MEASUREMENT REPORT message for event 2d to the Serving Radio Network Controller (SRNC). When the Serving Radio Network Controller (SRNC) receives event 2d, it commands the UE to begin Compressed Mode measurements.
Figure 17: Event 2d Trigger (Begin Compressed Mode) CPICH Ec/No
or CPICH RSCP
Best Cell in the Active Set
timeToTrigger2dEcno or
timeToTrigger2dRscp hysteresis2d
MEASUREMENT REPORT to RNC
usedFreqThresh2dEcno or
usedFreqThresh2dRscp
For this section of the document, usedFreqThresh2dEcno and usedFreqThresh2dRscp apply when the UE is served by its Serving Radio Network Controller (SRNC). These parameters do not apply if the UE is served by a Drift Radio Network Controller (DRNC). For cases wherein the UE is served by a Drift Radio Network Controller (DRNC), usedFreqThresh2dEcnoDrnc [RNC, -12, dB, Fixed] and
usedFreqThresh2dRscpDrnc [RNC, -106, dBm, Fixed] as configured on the SRNC apply.
5.3.4.2 Cease Compressed Mode – Current Used Frequency is Above Threshold (Event 2f) If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) Ec/No of the Best Cell in the Active Set becomes greater than the absolute threshold usedFreqRelThresh2fEcno [RNC, 2, dB, Fixed] + usedFreqThresh2dEcno + hysteresis2f [RNC, 2, 0.5dB, Fixed] / 2, for a time equal to timeToTrigger2fEcno [RNC, 640, ms, Fixed] , and the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set is greater than the relative threshold usedFreqRelThresh2fRscp [RNC, 6, dB, Fixed] + usedFreqThresh2dRscp + hysteresis2f [RNC, 2, 0.5dB, Fixed] / 2, for a time equal to timeToTrigger2fRscp [RNC, 640, ms, Fixed] , then event 2f occurs.
The UE then sends a MEASUREMENT REPORT message for event 2f to the Serving Radio Network Controller (SRNC). When the Serving Radio Network Controller (SRNC) receives event 2f, it commands the UE to stop all Compressed Mode measurements.
Figure 18: Event 2f Trigger (Cease Compressed Mode) CPICH Ec/No
or CPICH RSCP
Best Cell in the Active Set
timeToTrigger2dEcno and
timeToTrigger2fRscp hysteresis2f
MEASUREMENT REPORT to RNC
usedFreqRelThresh2dEcno + usedFreqRelThresh2fEcno and
usedFreqRelThresh2dRscp + usedFreqRelThresh2fRscp
5.3.4.3 Begin Compressed Mode – UE Transmit power is Above Threshold (Event 6d) If txPowerConnQualMonEnabled [RNC, 0=FALSE, Binary, Fixed] is set to TRUE and the UE
transmitted power is at maximum for a time equal to timeToTrigger6d [RNC, 320, ms, Fixed] , then event 6d occurs. The UE then sends a MEASUREMENT REPORT message for event 6d to the Serving Radio Network Controller (SRNC). When the Serving Radio Network Controller (SRNC) receives event 6d, it commands the UE to begin Compressed Mode measurements.
Figure 19: Event 6d Trigger (Begin Compressed Mode)
Maximum UE Tx Power Power
UE Transmission Power
timeToTrigger6d MEASUREMENT REPORT to RNC
5.3.4.4 Cease Compressed Mode – UE Transmit power is Below Threshold (Event 6b) If txPowerConnQualMonEnabled [RNC, 0=FALSE, Binary, Fixed] is set to TRUE and the UE
transmitted power becomes less than the absolute threshold ueTxPowerThresh6b [RNC, 21, dB, Fixed]
for a time equal to timeTrigg6b [RNC, 1280, ms, Fixed] , then event 6b occurs. The UE then sends a MEASUREMENT REPORT message for event 6b to the Serving Radio Network Controller (SRNC).
When the Serving Radio Network Controller (SRNC) receives event 6b, it commands the UE to stop Compressed Mode measurements.
Figure 20: Event 6b Trigger (Cease Compressed Mode) Power
UE Transmission Power
timeTrigg6b MEASUREMENT REPORT to RNC ueTxPowerThresh6b
5.3.4.5 Filtering, Offsetting and Weighting for Inter-Frequency or Inter-RAT measurements Filtering: Before Events 2d or 6d can occur, the measurements made by the UE are Filtered according to the formula below:
Fn = (1-a) F n-1 + a M n
Where:
• Fn = The updated measurement.
• Fn-1 = the last (old) filtered measurement result.
• Mn = the Ec/No as measured by the UE.
• a = 1/2(k/2) where k is filterCoefficient2 [RNC, 2, coeff, Fixed] or filterCoeff6 [RNC, 3, coeff, Fixed] respectively for Events 2x or 6x.
Offsetting: The updated measurement (Fn) is then offset by individualOffset(UtranCell) [Cell, 0, 0.5dB, Fixed].
Weighting: For Events 2d, and 2f, usedFreqW2d [RNC, 10, 0.1unit, Fixed] or usedFreqW2f [RNC, 10, 0.1unit, Fixed] respectively can be added in order to give heavier weight to cells in the Active Set that are not the best cell in the Active Set.
5.3.4.6 Whether to measure Inter-Frequency or Inter-RAT
If Compressed Mode measurements are required of the UE, the following parameters are considered:
• Inter-Frequency measurements can be made only if FddIfHoSupp [RNC, 0=FALSE, Binary, Fixed] =TRUE.
• Compressed Mode measurements of Inter-RAT neighbors can be made only if FddGsmHoSupp [RNC, 1=TRUE, Binary, Fixed] =TRUE.
If all Inter-Frequency neighbors are within the same Serving Radio Network Controller (SRNC), hoType [Cell, 1=GSM_PREFERRED, String, Fixed] determines if Inter-Frequency or Inter-RAT neighbors are evaluated.
If however, all of the Inter-Frequency neighbors are not within the same Serving Radio Network Controller (SRNC), a parameter called defaultHoType [Cell, 1=GSM_PREFERRED, String, Fixed] set per uarfcnDl [Cell, N/A, Integer, Variable] for the Drift Radio Network Controller (DRNC) is used. This parameter has been implemented due to a standards limitation in the Iur interface.
hoType [Cell, 1=GSM_PREFERRED, String, Fixed] and defaultHoType [Cell, 1=GSM_PREFERRED, String, Fixed] have the following settings which determine how the UE will behave.
• If at least one cell in Active Set has hoType [Cell, 1=GSM_PREFERRED, String, Fixed] =0 (IF-Preferred), then Inter-Frequency neighbors are evaluated.
• If at least one cell in Active Set has hoType [Cell, 1=GSM_PREFERRED, String, Fixed] =1 (GSM-Preferred), and no cell has hoType [Cell, 1=GSM_PREFERRED, String, Fixed] =0 (IF-Preferred), then Inter-RAT neighbors are evaluated.
• If all cells in the Active Set have hoType [Cell, 1=GSM_PREFERRED, String, Fixed] =2 (None), then neither Inter-Frequency nor Inter-RAT neighbors are evaluated.
5.3.4.7 Compressed Mode Measurement evaluation
Upon receiving either Event 2d or Event 6d from the UE, the Serving RNC sends a MEASUREMENT CONTROL message to the UE with additional Event based criteria that the UE will use to evaluate the results of the Compressed Mode (CM) measurements.
• The algorithm looks to see what initiated the Compressed Mode (CM) trigger.
• CPICH Ec/No from Event 2d
• CPICH RSCP from Event 2d
• UE Transmission Power from Event 6d
• If the Compressed Mode trigger measured Inter-Frequency or Inter-RAT measurements.
If the Event 2d reported by the UE indicated the trigger occurred due to CPICH Ec/No for Inter-RAT measurements the following occurs:
• If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) Ec/No of the Best Cell in the Active Set is less than usedFreqThresh2dEcno + utranRelThresh3aEcno [RNC, 2, dB, Fixed] – hysteresis3a [RNC, 4, 0.5dB, Fixed] / 2 and the Weighted absolute level of the GSM Broadcast Control CHannel (BCCH) is greater than gsmThresh3a [RNC, -98, dBm, Fixed] for a time equal to timeToTrigger3a [RNC, 6=100, ms, Fixed] then the UE sends a MEASUREMENT REPORT for event 3a to the Serving RNC and an Inter-RAT Handover commences.
Figure 21: Event 3a (EcNo)
GSM BCCH
Best Cell in the Active Set
timeToTrigger3a hysteresis3a
MEASUREMENT REPORT to RNC CPICH Ec/No or
BCCH RxLev
usedFreqThresh2dEcno + utranRelThresh3aEcno
gsmThresh3a
If the Event 2d reported by the UE indicated the trigger occurred due to CPICH RSCP for Inter-RAT measurements the following occurs:
• If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) Ec/No of the Best Cell in the Active Set is less than usedFreqThresh2dRscp + utranRelThresh3aRscp [RNC, 7, dB, Fixed] – hysteresis3a [RNC, 4, 0.5dB, Fixed] / 2 and the Weighted absolute level of the GSM Broadcast Control CHannel (BCCH) is greater than gsmThresh3a [RNC, -98, dBm, Fixed] for a time equal to timeToTrigger3a [RNC, 6=100, ms, Fixed] then the UE sends a MEASUREMENT REPORT for event 3a to the Serving RNC and an Inter-RAT Handover commences.
Figure 22: Event 3a (RSCP)
GSM BCCH
Best Cell in the Active Set
timeToTrigger3a hysteresis3a
MEASUREMENT REPORT to RNC CPICH RSCP or
BCCH RxLev
usedFreqThresh2dRscp + utranRelThresh3aRscp
gsmThresh3a
If Event 6d was reported indicating the trigger occurred due to UE Transmit Power, the following occurs for Inter-RAT measurements:
• If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set is less than usedFreqThresh2dRscp + utranRelThresh3aRscp [RNC, 7, dB, Fixed] + utranRelThreshRscp [RNC, 5, dB, Fixed] – hysteresis3a [RNC, 4, 0.5dB, Fixed] / 2 and the Weighted absolute level of the GSM Broadcast Control CHannel (BCCH) is greater than gsmThresh3a [RNC, -98, dBm, Fixed] for a time equal to timeToTrigger3a [RNC, 6=100, ms, Fixed] then the UE sends a MEASUREMENT REPORT for event 3a to the Serving RNC and an Inter-RAT Handover commences.
Figure 23: Event 3a (UE Tx)
usedFreqThresh2dRscp + utranRelThresh3aRscp + utranRelThreshRscp
GSM BCCH
Best Cell in the Active Set
timeToTrigger3a hysteresis3a
MEASUREMENT REPORT to RNC CPICH RSCP or
BCCH RxLev
gsmThresh3a
Filtering: Before Event 3a can occur, the measurements made by the UE are Filtered according to the formula below:
Fn = (1-a) F n-1 + a M n
Where:
• Fn = The updated measurement.
• Fn-1 = the last (old) filtered measurement result.
• Mn = the Ec/No as measured by the UE.
• a = 1/2(k/2) where k is gsmFilterCoefficient3 [RNC, 1, coeff, Fixed].
Offsetting: The updated measurement (Fn) is then offset by individualOffset(UtranCell) [Cell, 0, 0.5dB, Fixed].
Weighting: For Event 3a, utranCoefficient3 [RNC, 2, coeff, Fixed] can be used to give heavier weight to the serving cell while utranW3a [RNC, 10, 0.1unit, Fixed] can be used to give heavier weight to the candidate cell.
If the Event 2d reported by the UE indicated the trigger occurred due to CPICH Ec/No for Inter-Frequency measurements:
• If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) Ec/No of the Best Cell in the Active Set is less than usedFreqThresh2dEcno + usedFreqRelThresh4_2bEcno [RNC, -1, dB, Fixed] – hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2 and the Waited estimated quality of the unused frequency is above both the absolute thresholds nonUsedFreqThresh4_2bEcno [RNC, -13, dB, Fixed] + hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2 and nonUsedFreqThresh4_2bRscp [RNC, -105, dBm, Fixed] + hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2, for at least timeTrigg4_2b [RNC, 100, ms, Fixed] , then the UE sends a MEASUREMENT REPORT for event 2b to the Serving RNC and an Inter-Frequency Handover commences.
Figure 24: Event 2b (EcNo)
Best Cell in the AS 'used'
MEASUREMENT REPORT to RNC nonUsedFreqThresh4_2bRscp
Candidate 'non-unused'
Frequency
usedFreqThresh2dEcno + usedFreqRelThresh4_2bEcno
timeTrigg4_2b hyst4_2b
CPICH Ec/No or CPICH RSCP
nonUsedFreqThresh4_2bEcno
If the Event 2d reported by the UE indicated the trigger occurred due to CPICH RSCP for Inter-Frequency measurements:
• If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set is less than usedFreqThresh2dRscp + UsedFreqRelThresh4_2bRscp [RNC, -3, dB, Fixed] – Hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2 and the Weighted estimated quality of the unused frequency is above both the absolute thresholds nonUsedFreqThresh4_2bEcno [RNC, -13, dB, Fixed] + hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2 and nonUsedFreqThresh4_2bRscp [RNC, -105, dBm, Fixed] + hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2, for at least timeTrigg4_2b [RNC, 100, ms, Fixed] , then the UE sends a MEASUREMENT REPORT for event 2b to the Serving RNC and an Inter-Frequency Handover commences.
Figure 25: Event 2b (RSCP)
Best Cell in the AS
MEASUREMENT REPORT to RNC nonUsedFreqThresh4_2bRscp
Candidate (unused) Frequency
usedFreqThresh2dRscp + usedFreqRelThresh4_2bRscp
timeTrigg4_2b hyst4_2b
CPICH Ec/No or CPICH RSCP
nonUsedFreqThresh4_2bEcno
If Event 6d was reported indicating the trigger occurred due to UE Transmit Power, the following occurs for Inter-Frequency measurements:
• If the Filtered, Offset and Weighted Primary Common Pilot Channel (P-CPICH) RSCP of the Best Cell in the Active Set is less than usedFreqThresh2dRscp + UsedFreqRelThresh4_2bRscp [RNC, -3, dB, Fixed] +
utranRelThreshRscp [RNC, 5, dB, Fixed] – hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2 and the Weighted RSCP of the unused frequency is greater than nonUsedFreqThresh4_2bRscp [RNC, -105, dBm, Fixed] + hyst4_2b [RNC, 10, 0.1dB, Fixed] / 2, for at least timeTrigg4_2b [RNC, 100, ms, Fixed] , then the UE sends a MEASUREMENT REPORT for event 2b to the Serving RNC and an Inter-Frequency Handover commences.
Figure 26: Event 2b (UE Tx)
usedFreqThresh2dRscp + usedFreqRelThresh4_2bRscp +
utranRelThreshRscp Best Cell in the AS
'used'
MEASUREMENT REPORT to RNC nonUsedFreqThresh4_2bRscp
Candidate 'non-used'
Frequency timeTrigg4_2b
hyst4_2b CPICH RSCP
Filtering: Before Event 2b can occur, the measurements made by the UE are Filtered according to the formula below:
Fn = (1-a) F n-1 + a M n
Where:
• Fn = The updated measurement.
• Fn-1 = the last (old) filtered measurement result.
• Mn = the Ec/No as measured by the UE.
• a = 1/2(k/2) where k is filterCoeff4_2b [RNC, 2, coeff, Fixed].
Offsetting: The updated measurement (Fn) is then offset by individualOffset(UtranCell) [Cell, 0, 0.5dB, Fixed].
Weighting: For Event 2b, usedFreqW4_2b [RNC, 0, coeff, Fixed] can be used to give heavier weight to the serving cell while nonUsedFreqW4_2b [RNC, 0, coeff, Fixed] [RNC, 0, coeff, Fixed] can be used to