Cell Re Selection and Handover Parameters Specification

3G-2G Cell Reselection and Handover

Parameters Specification

Prepared by:

ETISALAT MS section

HUAWEI Radio Network Planning Department

2004-02-15

HUAWEIHUAWEI

3G-2G Cell Reselection and Handover Parameters Specification

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CONTENT

1. 3G to 2G cell reselection parameters specification ...................................................................... 3

2. 3G to 2G handover parameters specification ............................................................................... 6



1. 3G to 2G cell reselection parameters specification

Parameters Value Meaning

Qoffset1sn -3 -3dB

Min RX level -58 -115dBm

Hysteresis 1 2 4dB

Inter-RAT cell reselection threshold 3 6dB

Reselection delay time 0 7.68S

Min quality level -18 -18dB

Step 1: 3G measure Ec/Io < Inter-RAT cell reselection threshold + Min quality level

Step 2: GSM Rxlev measurement value > Min RX level

Step 3: GSM Rxlev measurement value – Qoffset1sn > 3G RSCP measurement value + Hysteresis1

Step 4: Reselection delay time

Step 5: Trigger 3G to 2G reselection

Parameters specification:

Step1: 3G measure Ec/Io < Inter-RAT cell reselection threshold + Min quality level

3G measure Ec/Io: the measurement Ec/Io value in 3G serving cell.

Inter-RAT cell reselection threshold: Threshold for inter-RAT cell reselection. When the quality

(CPICH Ec/Io measured by UE) of the serving cell is lower than the threshold plus Min quality

level of the cell, the inter-RAT cell reselection procedure will be started.

Value range: -16 ~ 10.

Physical value range: -32 ~ 20 ; step: 2.

Physical unit: dB.

Min quality level: Minimum required quality level corresponding to the CPICH Ec/Io. UE

can camp on the cell only when the CPICH Ec/Io measured is larger than the value of this

parameter; it will affect the call setup success rate.


Physical unit: dB.



Step 2: GSM Rxlev measurement value > Min RX level

GSM Rxlev measurement value: the measurement BCCH Rxlev value in GSM cell.

Min RX level: Minimum required Rxlev value of the GSM neighboring cell.

Value range: -58 ~ -13.

Physical value range: -115 ~ -25; step: 2.

Physical unit: dBm.

Step 3: GSM Rxlev measurement value – Qoffset1sn > 3G RSCP measurement value +

Hysteresis1


3G RSCP measurement value: the measurement RSCP value in 3G serving cell.

Qoffset1sn: Offset for GSM Rxlev measurement value. It is used for cell reselection process. The

greater the value is, the less is the probability of reselecting the GSM neighboring cell


Physical unit: dB.

Hysteresis 1: Hysteresis for 3G RSCP measurement value. It is used for cell reselection process.

The greater the value is, the less is the probability of reselecting the GSM neighboring cell

Value range: 0 ~ 20

Physical value range: 0 ~ 40; step: 2.

Physical unit: dB.

Step 4: Reselection delay time

Reselection delay time: If the signal quality of a GSM neighbor cell is better than the 3G serving

cell (satisfied the step 3) during the specified time of this parameter, the UE will reselect the

neighbor cell. It is used to avoid ping-pong reselection between different cells

Value range: 0 ~ 31

Physical unit: second.



The actual value of reselection delay time setting is depended on the DRX cycle length

coefficient.

DRX cycle length coefficient: Used by UE to calculate the DRX cycle length of the CN domain.

Value range: 6 ~ 9.

Recommendation value: 8.

How to calculate the reselection delay time by DRX cycle length coefficient. Refer to 3GPP

25.133

Formula: DRX cycle length = 2n * 10ms

E.g. If DRX cycle length coefficient = 8 then

DRX cycle length = 28 * 10ms = 2560ms=2.56s

Then use table below to get the reselection time and number of DRX cycles (defined by 3GPP)

DRX cycle length [s] TmeasureGSM [s] (number of DRX cycles)

0.08 2.56 (32)

0.16 2.56 (16)

0.32 5.12 (16)

0.64 5.12 (8)

1.28 6.4 (5)

2.56 7.68 (3)

5.12 10.24 (2)

Step 5: Trigger 3G to 2G reselection



2. 3G to 2G-Handover parameters specification

Parameters Value Meaning

Cell individual offset 0 0

GSM RSSI threshold 15 -95dB

Hysteresis 2 1dB

Inter-RAT handover trigger time 1000 1S

Filter coefficient UU_FC4 7

Report interval UU_RILE_1 1S

Inter-freq measure start RSCP threshold -95 -95dBm

Inter-freq measure end RSCP threshold -90 -90dBm

2D Hysteresis 6 3dB

2F Hysteresis 6 3dB

2D trigger time 640 0.64S

2F trigger time 640 0.64S

Step 1: 3G RSCP measurement value = < Inter-freq measure start RSCP threshold - 2D Hysteresis/2

Step 2: Filter coefficient

Step 3: Report interval

Step 4: GSM Rxlev measurement value + Cell individual offset >= GSM RSSI threshold

+ Hysteresis/2

Step 5: Inter-RAT handover trigger time

Step 6: Trigger Inter-RAT handover

Parameters specification:

Step1: 3G RSCP measurement value = < Inter-freq measure start RSCP threshold –

2D Hysteresis/2

3G RSCP measurement value: the measurement RSCP value in 3G serving cell.

Inter-freq measure start RSCP threshold: UE will report 2D event and then RNC will send signal

to start CM and inter-frequency measurement when the measured value is lower than this

threshold.

Value range: -115 ~ -25



Physical unit: dBm

2D Hysteresis: Hysteresis value of the 2D event. This parameter value is related to the slow

fading characteristic. The greater this parameter is valued, the less ping-pong and misjudgment

can be caused. However, in this case, the event cannot be triggered in time.

Value range: 0 ~ 29

Physical value range: 0 ~ 14.5 with the step size of 0.5

Physical unit: dB

2D event refer to 3GPP 25.331

Triggering condition

Equation 1:

2/22 ddUsedUsed HTQ

The variables in the formula are defined as follows:

QUsed is the quality estimate of the used frequency.

TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.

H2d is the hysteresis parameter for the event 2d.

Leaving triggered state condition

Equation 2:

2/22 ddUsedUsed HTQ



TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.

H2d is the hysteresis parameter for the event 2d.

2D trigger time: 2D event trigger delay time. This parameter value is related to the slow fading

characteristic. The greater this parameter is valued, the less the misjudgment probability is.

However, the response speed of the event to the measurement signal change becomes lower.

Value range: D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640,



D1280, D2560 and D5000

Physical value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560 and

5000

Physical unit: ms

Inter-freq measure end RSCP threshold: UE will report 2F event and then RNC will send signal

to stop CM and inter-frequency measurement when the measured value is higher than this

threshold.

Value range: -115 ~ -25

Physical unit: dBm

2F Hysteresis: Hysteresis value of the 2F event. This parameter value is related to the slow fading

characteristic. The greater this parameter is valued, the less ping-pong and misjudgment can be

caused. However, in this case, the event cannot be triggered in time.

Value range: 0 ~ 29

Physical value range: 0 ~ 14.5 with the step size of 0.5

Physical unit: dB

2F event refer to 3GPP 25.331

Triggering condition:

Equation 1:

2/22 ffUsedUsed HTQ



TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.

H2f is the hysteresis parameter for the event 2f.

Leaving triggered state condition:

Equation 2:

2/22 ffUsedUsed HTQ





TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.

H2f is the hysteresis parameter for the event 2f.

2F trigger time: 2F event trigger delay time. This parameter value is related to the slow fading

characteristic. The greater this parameter is valued, the less the misjudgment probability is.

However, the response speed of the event to the measurement signal change becomes lower.

Value range: D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640,

D1280, D2560 and D5000

Physical value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560 and

5000

Physical unit: ms


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Step 2: Filter coefficient

Filter coefficient: Inter-RAT measurement L3 filter coefficient, the greater this parameter is valued,

the stronger smoothing effect can be caused to the signal and the greater anti-slow fading ability

can be possessed. However, the signal change tracing ability becomes weaker.

Value range: D0, D1, D2, D3, D4, D5, D6, D7, D8, D9, D11, D13, D15, D17, D19.

Physical value range: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19.

Filter coefficient 0 1 2 3 4 5 6 7 8 9 11

Iterative report 1 2 3 5 7 10 15 21 30 42 85

Step 3: Report interval

Report interval: Time interval in which UE reports the inter-RAT measurement results to RNC

periodically.

Time

2D threshold

2D Hysteresis/2

2D Hysteresis/2

-100dBm

RSCP

-85dBm

Start 2D measurement

2D Trigger time Send 2D event to RNC

Stop 2D measurement

Start 2F measurement

2F Trigger time Send 2F event to RNC

Stop 2F measurement

2F threshold

2F Hysteresis/2

2F Hysteresis/2


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Value range: D250, D500, D1000, D2000, D3000, D4000, D6000, D8000, D12000, D16000,

D20000, D24000, D28000, D32000, D64000.

Physical value range: 250, 500, 1000, 2000, 3000, 4000, 6000, 8000, 12000, 16000, 20000,

24000, 28000, 32000, 64000.

Physical unit: ms.

Step 4: GSM Rxlev measurement value + Cell individual offset >= GSM RSSI threshold

+ Hysteresis/2


GSM RSSI threshold: Requirement for the BCCH Rxlev of GSM cell in the inter-RAT handover.

Cell individual offset: It is used in inter-RAT handover decision process. The greater the value is,

the more is the probability of handover to the GSM cell.


Physical unit: dB.

Hysteresis: It decides whether to trigger the GSM handover decision together with the GSM RSSI

threshold. The value can be decreased to some degree in areas with less shadow fading, and

increased in areas with more shadow shading.

Value range: 0 ~ 15.

Physical value range: 0~7.5; step: 0.5.

Physical unit: dB.

Reference 3GPP 25.331

Triggering conditions:

Equation 1:

2/HTCIOM RATOtherRATOtherRATOther


MOther RAT is the measurement quantity for the cell of the other system.


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CIOOther RAT is the cell individual offset for the cell of the other system.

TOther RAT is the absolute threshold that applies for the other system in that measurement.

H is the hysteresis parameter for inter-RAT handover

Leaving triggered state conditions:

Equation 2:

2/HTCIOM RATOtherRATOtherRATOther


MOther RAT is the measurement quantity for the cell of the other system. MOther RAT is expressed in

dBm.

CIOOther RAT is the cell individual offset for the cell of the other system.

TOther RAT is the absolute threshold that applies for the other system in that measurement.

H is the hysteresis parameter for inter-RAT handover

Step 5: Inter-RAT handover trigger time

Inter-RAT handover trigger time: The inter-RAT handover to GSM procedure will be started if the

GSM BCCH Rxlev always satisfies the inter-RAT handover decision (step 4) during the specified

period of this parameter.

Value range: 0 ~ 64000. Step: 1

Physical unit: ms

Step 6: Trigger Inter-RAT handover

Documents

Cell Re Selection and Handover Parameters Specification