gbc_005_e1_1 handover and power control-27

8/13/2019 GBC_005_E1_1 Handover and Power Control-27

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GBC_005_E1_1

Handover and Power control

ZTE University

GSM-BSS Team


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Content

Handover

Power control


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Handover reasons

Handover: Hand-over is a process that transfers a MS

that is in setting up or busy status to a new traffic channel

Handover reasons

Weak signal

Bad quality

Severe interference

Large TA

Macro-micro handover

Better cell handover

Handover


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Types of handover

Intra-cell hand-over: hand-over occurs in the same cell.

Controlled independently by the BSC the cell attached to.

Inter-cell hand-over of the same BSC: involving by MSC is

not needed. Inter-BSC hand-over of same MSC: Before and after hand-

over, the two cells belong to different two BSCs which are

controlled by the same MSC. All the MSC and BSCs are

involved. Inter-MSCs hand-over: Before and after hand-over, the two

cells belong to different two MSCs. All the relevant MSCs

and BSCs are involved.

Handover


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Network overview

MSCBSC

BTS

MS

BSC Evaluation and Decision

of HO

MSC: routes the call to the other

MSC during Inter-MSC HO

BTS preprocess

measurements UL and DL

MS measures:

Signal Strength DL own cell

and neighboring cells, Quality

DL

Signal Strength of

Neignboring Cells

BTS measures:

Signal Strength UL, Quality

UL , TA

Handover


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Intra-cell handover signaling process

MSBTS BSC MSC

Meas RepMeas Res

Phy Context Req

Phy Contest Conf

Chan Act

Chan Act ACK

Assign Command

SABMEst Ind

UA

Assign CompleteHo Perform

Deact SACCH

RF Chan Release

RF Chan Rel ACK

Handover


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Inter-cell handover signaling process

DT1HO PERF

HO CMD

CH ACT

MEAS REP

RF CH REL ACK

RF CH REL

DIHO COM

EST IND

HO DET

CH ACT ACK

MS BTS1 BTS2 BSC MSC

MEAS RES

DRHO CMD

HO ACCESS

PHY INFO

SABM

UA

HO COM

Handover


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Handover layer

Cell layer is relative defined by operator

Not defined

Upper layer

Same layer

Lower layer

Handover target cell is sorted by

Priority

Traffic

Radio environment

Handover


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Measurement report

Period 480ms

MS downlink measurement report (carried by SACCH) :

Downlink RXLEV

Downlink RXQUAL(BER)Other adjacent cells downlink RXLEVless than 6,

designated by BA list)

Measurement report made by BTS

Uplink RXLEV

Uplink RXQUAL

TA

Interference strip

Handover


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Preprocess of measurement report

PROCESSING OF BTS MEASURED DATA

RXLEV_XXXXDL or UL

For each connection, at most 32 sampling data are retained and

the average of RX level is calculated out by BSS in each

SACCH period.

Adjacent cellsBCCH carrier receiving level RXLEV_NCELL(n)

For each connection and each cell, the most 32 sampling data

are stored by BSS to calculate out the adjacent cells BCCH

carrier receiving level.

Handover


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Power budgetPBGT)

PBGT(n)=(Min(MS_TXPWR_MAX,P)RXLEV_DLPWR_C_D) (Min(MS_TXPWR_MAX(n),P)RXLEV_NCELL(n))

Where

PWR_C_Dis the difference of cell-allowed downward maximum

power with actual power

MS_TXPWR_MAX(current traffic channel)

MS_TXPWR_MAX(n)(adjacent cell n traffic channel)

P is the maximum transmission power of MS

Handover


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Parameters in Handover judgement

PARAMETER FUNCTION

UpLevThNP upward level threshold

UpQualThNP upward quality thresholdDwLevThNP downward level threshold

DwQualThNP downward quality threshold

UpIntfThNP upward interference threshold

DwIntfThNP downward interference threshold

MsDistThNP distance thresholdsame unit with TA)HoMarginn Adjacent cells hand-over margin

Handover


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Threshold Comparison

1.Hand-over will occur if at least P out of N upward levels

are lower than UpLevTh.

2. Hand-over will occur if at least P out of N downwardlevels are lower than DwLevTh.

3. Hand-over will occur if at least P out of N upward levels

are higher than UpQualTh.

4. Hand-over will occur if at least P out of N downward

levels are higher than DwQualTh.

Handover

H d


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Threshold Comparison

5. Hand-over will occur if the latest P out of N upward

levels are higher than UpIntfTh and condition 3 is met at

the same time.

6. Hand-over will occur if the latest P out of N downwardlevels are higher than DwIntfTh and condition 4 is met at

the same time.

7. Hand-over will occur if the latest P out of N TAs are

higher than MsDistTh.

8. Hand-over will occur if PBGT of some adjacent cell is

higher than its corresponding HoMargin.

Handover

H d


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Selection of target cell

Principle 1 ( All type of handover )

AvRxLevNCell(n) > RXLEV_MIN(n) + MAX(0,(MS_TXPWR_MAX(n)-

P(n)))

Principle 2 ( PBGT handover )

PBGT(n ) > HO_MARGIN(n)

Principle 3 ( Quality handover )

AvRxLevNCell(n) > avRxLevDL + HO_MARGIN_QUAL(n)

Principle 4 ( Signal level handover )

AvRxLevNCell(n) > avRxLevDL + HO_MARGIN_LEVEL(n)

Handover

H d


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Sort order of target cell

Principle:

Cell dynamic priority

PBGT

Dynamic priority

Static priority: 07

Ratio of cell resource: idle TCH/ total TCH

Handover

H d


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Handover penalty strategy

Inter-cell handover

PenaltyLevOffset

PenaltyCount


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Content

Handover

Power control

Power control


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Purpose of power control

Lower interference within a cell

Save power

Consideration: Call quality or data transmission quality be

guaranteed

A B

Power control

Power control


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Power control procedure

Power

controlperiod:

480ms

MS

BTS

BSC

SACCH

MEASURED DATA

AVERAGE MEASURED DATA

POWER CONTROL DECISION

SEND POWER CONTROL COMMAND

MEASURED DATA CORRECTION

Power control

Power control


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Relation of level with power control

63

0

Upper limit

Lower limit

Fast power control

zone

Fast power control zone

High

Low

Normal

Power control

Power control


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Relation of BER with power control

0

7

Upper limit

Lower

limit

Fast power control

zone

Fast power control zone

Low

High

Normal

Power control

Power control


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Relationship between RXQUAL and BER

RXQUAL BER (%) Typical(%)

0 BER


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Power control strategy

Normal Level LEVELCAUSE = 0

Low Level LEVELCAUSE = 1

High Level LEVELCAUSE = 2

Normal BERQUALCAUSE = 0

Low BER QUALCAUSE = 1

High BER QUALCAUSE = 2

LEVELCAUSE QUALCAUSE OUTPUT

0 2 INCREASE

1 0 STAY

1 1 STAY

1 2 INCREASE2 0 DECREASE

2 1 DECREASE

2 2 INCREASE

Power control

Power control


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RANGE OF POWER CONTROL

BTS Power Control BTS has 6 classes of static power configured by network, each

class has 15 levels of dynamic power which can be configured bynetwork.

MS Power Control

GSM900 class A MS power capability 43dbm20W

GSM900 class B MS power control 39dbm8W

GSM900 class C MS power capability 37dbm5W

GSM900 class D MS power capability 33dbm2W

GSM900 class E MS power capability 29dbm0.8W

GSM900 power control range of MS is 43dbm ~ 5dbmat

least 2dbm one step

DCS1800 class A MS power control capability 30dbm1W

DCS1800 class B MS power control capability 24dbm0.25W

DCS1800 class C MS power control capability 36dbm4W

DCS1800 power control range 36dbm ~ 0dbm2dbm one step

Power control


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gbc_005_e1_1 handover and power control-27

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