bsspar chapter 07 handover

8/12/2019 BSSPAR Chapter 07 Handover

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156 NOKIA 2000 BSSPARS9 Jun 00

HANDOVER PROCESS

BSSPAR S9


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HANDOVER PROCESSContents

1. Overview2. Handover Decision

3. Target Cell Selection

4. Algorithms5. Power Budget Handover

6. Level & Quality Handover

7. Umbrella Handover

Combined Umbrella & Power Budget

MS Speed

8. Imperative Handover

9. Timers for Handovers

10. C/I Based Handover Candidate Evaluation

11.Traffic Reason handover


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HANDOVER PROCESSCauses

Timing Advance

Adjacent Cells

Downlink Quality

Uplink Quality AV_RXQUAL_UL_HO

AV_RXQUAL_DL_HO

Downlink Level

Uplink Level AV_RXLEV_UL_HO

AV_RXLEV_DL_HO

AV_RANGE_HO

AV_RXLEV_NCELL(n)

QUALITY&

INTERFERENCE

QUALITY&

INTERFERENCE

LEVEL

LEVEL

DISTANCE

DISTANCE

PERIODICCHECKS

UMBRELLA

UMBRELLA

POWER BUDGET

POWER BUDGET

IMPERATIVEHO

CHANNEL ADMINISTRATION

CHANNEL ADMINISTRATION

DIRECTED RETRY

DIRECTED RETRY

THRESHOLDCOMPARISON

RAPID FIELD DROP

RAPID FIELD DROP

Others:

Intelligent Underlay Overlay

Traffic Reason

.

MS SPEED

MS SPEED

MS Speed AV_MS_SPEED


4/48159 NOKIA 2000 BSSPARS9 Jun 00

HANDOVER PROCESSHandover Decision

Handover process may be triggered by

Quality, field strength or distance values

fall below/exceed their threshold

Periodic checksPower budget HO

Umbrella HO



HANDOVER PROCESSHandover Priority

Handover priority

1. Uplink and downlink Interference2. Uplink quality

3. Downlink quality

4. Uplink level

5. Downlink level6. Distance

7. Rapid Field Drop

8. Slow moving MS

9. Better cell i.e. Periodic check (Power Budget HO or Umbrella HO)

10. PC: Lower quality/level thresholds (UL/DL)

11. PC: Upper quality/level thresholds (UL/DL)


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HANDOVER PROCESSTarget Cell Selection (1/2)

Load check of Candidates by btsLoadThreshold (0..100%)

If overloaded priority decreased by hoLoadFactor(0...7)

Best candidates to RR Management:

intra BSC HO max 16 cells under the same BSC as the source cell

inter BSC HO numberOfPreferredCells

1.

Only for AdjacentCell of thesame BSC

If two or more Adjacent cells with equal priorities

-> Ranking based on radio properties

Comparison of priorities of Candidates (hoLevelPriority

(0..7))

2.

3.



HANDOVER PROCESSTarget Cell Selection (2/2)

All cells have equal priority

cell a b c

Rx_Level -75 -80 -83

1. Load overl. overl. n.overl.

hoLoadFactor 1 1 1

2. Priority 3 3 3

New Priority 2 2 3

3. Rx_Level -75 -80

=> cell list c , a ,b

One cell has higher priority because of some reason

cell a b c

Rx_Level -75 -80 -83

1. Load n./overl. n.overl. n.overl.

hoLoadFactor 2 1 1

2. Priority 4 3 3

New Priority 4/2 3 3

3. Rx_Level -75 -80/-80 -83

=> cell list a,b,c (if cell a is not overload)

=> cell list b,c,a



HO flow chart

Eq. 1or

Eq. 1'

Adj1..Adj2.Adj3.------------------------

--------------------------------Adj32

Adj1Adj3------------------

Adjn

Eq.2

orEq.2'

Target Cell Evaluation

Cell ranked according to priority/load

Adj1Adj3-------Adji.

Load informationfrom the RRmanagement

BSC


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HANDOVER PROCESSPower Budget Handover (1/2)

Trigger

Periodic Check ( hoPeriodPBGT )

Candidate Selection

Equation 1 & 2 usedPriority and Load Considered

Performed ONLY between cells of the same "Layer" if:

umbrella HO is enabled

in inter-band HO case

hoPeriodPBGT 1 ... 63 (SACCH Period)

enablePwrBudgetHandover Y / N

Parameter Value

HOC

rxLevMinCell(n) -110 -47 dBmmsTxPwrMax(n) 5 43 dBm

hoMarginPBGT(n) -24 63 dB ADJC


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HANDOVER PROCESSPower Budget Handover (2/2)

Equations 1 and 2 are used

Serving Cell: Best Adjacent Cell:

AV_RXLEV_DL_HO = -90 dBmmsTxPwrMax = 33 dBm (= 2W)

btsTxPwrMax = 42 dBm (= 16 W)

BTS_TX_PWR = 42 dBm = (16 W)

hoMarginPBGT(n) = 6 dB

AV_RXLEV_NCELL(n) = -80 dBmrxLevMinCell(n) = -99 dBm

msTxPwrMax(n) = 33 dBm (= 2W)

btsTxPwrMax = 42 dBm (= 16 W)

AV_RXLEV_NCELL(n) > rxLevMinCell(n) + Max (0, msTxPwrMax(n) - msTxPwrMax)

-80 dBm > -99 dBm + (33 dBm - 33 dBm) = -99 dBm

1.

PBGT = ((msTxPwrMax- msTxPwrMax(n)) - (AV_RXLEV_DL_HO -AV_RXLEV_NCELL(n)) - (btsTxPwrMax - BTS_TXPWR)

PBGT = ((33dBm-33dBm)-(-90 - -80)-(42dBm-42dBm)

= 10 dB

10 dB > 6 dB OK !!!!

2.

HANDOVER PROCESS


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HANDOVER PROCESSHandover due to Level (1/2)

Trigger

Threshold Comparison ( hoThresholdsLevUL/DL (px - nx) )

Candidate Selection

Equation 1 usedEquation 2 used if enableHoMarginLevQual = N

Equation 2' with hoMarginLev used ifenableHoMarginLevQual = Y

Priority and Load Considered

hoThresholdLevUL/DL -110 -47

px 1 32

nx 1 32

Parameter Value

HOC


hoMarginLev(n) -24 24 dB ADJC

HANDOVER PROCESS


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HANDOVER PROCESSHandover due to Level (2/2)

Equations 1 and 2 are used if parameter enableHoMarginLevQual is set Yes

2 dB

hoMarginLev = 4 dB

Trigger for Handover due to Level

A

B

Threshold (Lev)

-95 dBm

=> Cell B is not selected as candidate for

HO due to level since 2dB < 4 dB

HANDOVER PROCESS


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HANDOVER PROCESSHandover due to Quality (1/2)

Trigger

Threshold Comparison ( hoThresholdsQualUL/DL (px - nx) )

Candidate Selection

Equation 1 usedEquation 2 used if enableHoMarginLevQual = N

Equation 2' with hoMarginQual used ifenableHoMarginLevQual = Y


hoThresholdQualUL/DL 0 7

px 1 32

nx 1 32

Parameter Value

HOC


hoMarginQual(n) -24 24 dB ADJC

HANDOVER PROCESS


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HANDOVER PROCESSHandover due to Quality (2/2)

Equations 1 and 2 are used if parameter enableHoMarginLevQual is set Yes

2 dB

hoMarginQual = 0 dB

Trigger for Handover HO due to Quality

A

B

=> Cell B is selected as potential candidate for

HO due to Quality since 2 dB > 0 dB

HANDOVER PROCESS


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HANDOVER PROCESSHandover due to Interference (1/2)

Trigger : Threshold Comparison

Threshold Comparison for Quality ( hoThresholdsQualUL/DL (px - nx) )

Threshold Comparison for Level ( hoThresholdsInterferenceUL/DL (px -nx) )

Candidate Selection

Priority for InterCell / Intracell HO selected at BSC independently for UL / DL Priority InterCell HO

Quality HO if any candidate

If not IntraCell HO

Priority IntraCell HO

hoThresholdInterferenceUL/DL -110 -47

px 1 32nx 1 32

enableIntraHoInterfUL/DL Y / N

Parameter Value

hoPreferenceOrderInterfUL/DL INTER / INTRA

BSC

HOC

BSC


HANDOVER PROCESS


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HANDOVER PROCESSHandover due to Interference (2/2)

Equations 1 and 2 are used if parameter enableHandoverMarginQual is set Yes

hoThresholdQual = 4

hoThresholdInterferenceDL = -85 dBm

hoPreferenceOrderInterfDL = intra Trigger for Handover due to Interference

A

B

- Field strength higher than threshold

- Bad quality

=> interference

=> intra cell handover !!

Threshold (Interference Lev)

-85 dBm

5

0

HANDOVER PROCESS


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HANDOVER PROCESSUmbrella Handover (1/2)

6 dB

Umbrella

Handover

A

B-90 dBm

Handover due

to Level

Macro cell

Micro cellExample

GSM MS class 4 (33 dBm)

gsmMacrocellThreshold = 35 dBm

gsmMicrocellThreshold = 33 dBmmsTxPwrMax(n) = 33 dBm

hoLevUmbrella = -85 dBm

hoThresholdLevDL = -90 dBm

-85 dBm

Umbrella

Handover

Handover due

to Level

Trigger

Periodic Check ( hoPeriodUmbrella )

Candidate Selection

Equation 1' usedConsistency between mobile classmark and target cell power

constraints


Multi-Layered Network

HANDOVER PROCESS


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HANDOVER PROCESSUmbrella Handover (2/2)

Max power capability of MS >= gsmMacrocellThreshold

HO allowed only to a macrocell ( MS_TXPWR_MAX(n) >=gsmMacrocellThreshold )

gsmMicrocellThreshold < Max power capability of MS < gsmMacrocellThreshold

HO only to middle size cell ( gsmMicrocellThreshold < MS_TXPWR_MAX(n)

bsspar chapter 07 handover

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