3- OMO133030 BSC6900 GSM V9R13 Handover Algorithm I ISSUE 1.02.ppt

8/10/2019 3- OMO133030 BSC6900 GSM V9R13 Handover Algorithm I ISSUE 1.02.ppt

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Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved. Page1

Foreword

Handover is a key technology of mobile communication system andmake continued conversation possible.

Handover algorithm in Huawei product is flexible and powerful.


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Contents

1. Introduction of Handover

2. HO Algorithm Process


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Contents




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Purposes of HO

To keep a continuous communication with a moving MS

To improve network service performance

To reduce the call drop rate

To reduce the congestion rate


7/162Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved. Page6

Classification by Reason

No DL MR Emergency HOTiming Advance (TA) HOInterference HOBad Quality (BQ) HO

Emergency HO

Enhanced Dual Band HO

Load HO

Normal HO

1

2

3

4

Classification by

ReasonEDGE HOPBGT HOLayer HO

MS Fast Moving HOConcentric Cell HOAMR HO


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Classification by Synchronization

CELL

Case 1

Synchronous Handover: the target BTS shall not send PHY INFO message

Case 2

Asynchronous Handover: the target BTS shall send PHY INFO message

Case 3 Case 4 Case 5

MSC

BSC

BTS

BSC BSC

MSC

BTS BTSBTS BTS

NSS Network


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Classification by Equipment andChannel

SDCCH TCH (Direct Retry)

SDCCH SDCCH

Intra Cell HO

Inter Cell HO

Intra BSC HO

Intra MSC HO

Inter MSC HO

TCH TCH


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Contents




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Contents


2.1 General HO Process

2.2 Measure and Measurement Result Report

2.3 Measurement Report Preprocessing

2.4 Handover Judgment

2.5 Handover Implementation


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General HO Process

MS Goes into New Dedicated Mode

MS Goes into Dedicated Mode

Measure and Measurement Result Report1

Measurement Report Preprocessing2

Handover Judgment3

Handover Implementation4


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The downlink measurement reportof the neighbor cell (BCCH)

Measurement Report

Uplink MR includes uplink receiving level and quality.

Downlink MR includes downlink receiving level, downlink

receiving quality of the serving cell and other downlink receiving

levels from the neighbor cells.

Serving cell

Neighbor cell

The uplink MR

The downlink MR


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Measurement Report


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Period of Measurement Report

The downlink MR is sent to BTS in SACCH uplink

The interval is 480ms/per time when MS is on TCH

The interval is 470ms/per time when MS is on SDCCH

12TCH 12TCH1SACCH 1 Idle

480ms 4 TCH Multi-frames


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General HO Process



Measurement Report Preprocessing

Handover Judgment3



2


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MR Preprocessing

MR Preprocessing

Interpolation

Recover the lost

measurement report

Filtering

Smooth the instantaneous

fading point


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MR Interpolation

MR MR

No. n

No. n+4 MR

MR MR

Missing bysome reasons


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MR Filtering

MR

MR MR

MR

MR

Filter----Average severalconsecutive MRs

MR


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Data Configuration of MRPreprocessing


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Data Configuration of MRPreprocessing


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General HO Process

MS Goes into NewDedicated Mode

MS Goes intoDedicated Mode

Measure and MeasurementResult Report1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO


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Penalty Processing

Intra-cellHO

HO FailsEmergency(TA&BQ)HO

MS FastMoving

HO

Concentric

Cell HO

Penalty

Punish onthe target

cell

Punish on theoriginal cell

Punish on other

high priority layercells

AMR HOFails


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Penalty for Handover Failure

Punish the target cell when a HO fails.

This is to avoid the MS to select this cell again in next HO judgment.

BSC punishes Cell D bysignal level value

Cell A

Cell D

HO fails X

-80dBm

-75dBm

Within penalty time -75dBm-30dB=-105dBm


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Data Configuration of Penalty forHandover Failure


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Penalty for Emergency Handover

Punish the original cell when an emergency HO ( due to BQ and

TA) occurs.

Cell A

Cell D

BQ or TA HO

MS successfully handovers from cell A tocell D for BQ or TA, so original cell Ashould be punished-80dBm

-75dBm

Within penalty time -80dBm-63dB -143dBm


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Data Configuration of Penalty forEmergency Handover


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Back? No way!

Umbrella

Micro cell

Penalty for MS Fast-moving Handover

Giving penalty on the other three layers(Non-umbrella Layer ) after MShandovers to Umbrella cell by fast-moving-HO.

This is to keep MS staying in the umbrella cell and avoid frequent HO.


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Data Configuration of Penalty for MSFast-moving Handover


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Underlaid

Overlaid Do not attempt

again duringpenalty timeafter one failed

HO(OU)!

Penalty for Concentric Cell

A new concentric cell HO is prohibited within a penalty time after aconcentric cell HO failure.

Do notattempt again

after N failedHO(U->O)!


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Data Configuration of Penalty forConcentric Cell


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Underlaid

Overlaid

Do notattempt backtoo fast!

Penalty for Enhanced Concentric Cell

A new U O HO is prohibited within a penalty time after aO U HO is performed successfully.


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Data Configuration of Penalty forEnhanced Concentric Cell


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Penalty for Intra-cell HO

A new intra-cell HO is prohibited if it occurs too frequently.

3s 4s 5s 20s Duration (s)0

Penalty time

Intra-cellHO Time

2nd.3rd.

4th.

Max. consecutive HO times: 3

Forbidden time after Max. times: 20s

Interval for consecutive HO Jud: 6s

1st.

TR X1

TR X2

TR X3

TR X4

TR X5


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Data Configuration of Penalty forIntra-cell HO


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Data Configuration of Penalty for AMRFR HR Handover Failure


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General HO Process




MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO


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Ranking Processing

M rule

K rule

Basic ranking

16 bits ranking

Network feature adjustment

The ranking result: target cell selection of handover


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M Rule

Begin

Finish to allneighbor cells?

No

Yes

the cell overload ? Yes

RX_LEV_DL(n) < [Min DL Poweron HO Candidate Cell](n)+

[Min Access Level Offset](s->n)?

RX_LEV_UL(n) < [Min UP Power on

HO Candidate Cell](n)+[Min Access Level Offset](s->n)?

Delete this cell fromthe cell list

Yes

No

No

No

No

End

For service cell:Min Access Level Offset=0

M rule will remove theunsuitablecells from the candidate cell listaccording to the flow.

Yes


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Data Configuration of M Rule


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Data Configuration of M Rule


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Network Feature Adjustment

After network feature adjustment, all the candidate cells have theirown 16 bits value.

The smaller the value is, the higher the handover priority and

position of the cell are in the candidate cell list, then it is possible to

be the candidate cell.


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The 1st

~3rd

bitsThe bit value indicates the priority of downlink receiving level

according to the cell signal level and the penalty process taking place

beforehand.

The values come from max. 6 candidate cells and 1 serving cellaccording to the level ranges from 000~110. The value for the cell

with the strongest signal level is 000, for the cell with second

strongest signal level is 001 and so on.

Actually that is the core of K rule.

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1


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Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

-85dBm

-80dBm

-90dBm

-83dBm

-75dBm

-95dBm

-70dBm

3 2 1 RX_LEV Cell

-70dBm F

-75dBm D

-80dBm B

-83dBm C

-85dBm S

-90dBm A

-95dBm E

Candidate cell list

high >low

Question(The 1 st ~3 rd Bits)


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The 4th

bit: [Inter-cell HO hysteresis] bit.

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

serving cell?

Always set to 0

No

RX_LEV_DL (n) >=RX_LEV_DL (s) +

[Inter-cell HO hysteresis] (s->n) ?

Yes

Set to 0 Yes

Set to1

No


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Data Configuration of Inter-cell HO Hysteresis


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Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

-85dBm

-80dBm

-90dBm

-83dBm

-75dBm

-95dBm

-70dBm

4 3 2 1 Current HO hys. RX_LEV Cell

-70dBm F

-75dBm D

-80dBm B

-83dBm C

-85dBm S

-90dBm A

-95dBm E

Candidate cell list

high >low

Question(The 4 th Bit)

Suppose: [Inter-cell HO hysteresis] (s->n)=4


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Network Feature AdjustmentThe 5 th~10 th bits

The bit value is decided according to their position in Huawei hierarchical

network structure.

Huawei cell layers can be divided into 4 layers and each layer can be further

divided into 16 different priorities (levels).

So there are 64 different priorities in Huawei hierarchical cell structure.

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

P layer (0~3) P level (0~15)

P layer_level (0~63)


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Hierarchical Cell Structure

GSM900 Cell

Micro Cell

Umbrella Cell GSM 900

GSM1800 GSM1800GSM1800

GSM 900

GSM900GSM900

GSM1800GSM1800

GSM1800 Cell

GSM 900

GSM900GSM900

GSM1800GSM1800

Layer 4low

Layer 3

Layer 2

Layer 1high


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Data Configuration of Cell HierarchicalNetwork Structure


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Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

L3 P1L3 P1

L2 P1

L2 P5

L1 P3

L3 P4

L2 P1

10 9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

E

Candidate cell listhigh >low

Question(The 5 th~10 th Bits)


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The 11th

bit: The bit value is decided by cell-load-sharing criterion.This bit is affected by 14 th bit.

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

System load>=[System Flux Threshold for Load HO](s)or [Load HO Allowed](s) =No ?

Yes 11 th bit isturned off

serving cell?

set to 0

No Yes

Cell load >= [LoadHO Threshold](s)?

set to 1 set to 1

cell load >=[ Load Req.on Candidate Cell](n)?

set to 0

Yes

No

Yes

No

No


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Data Configuration of Cell-load-sharing


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Data Configuration of Cell-load-sharing


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Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

11 10 9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

E


Question(The 11 th Bit)Suppose system flow [Load Req. on Candidate Cell](n)serving cell: load(s) >= [Load HO Threshold](s)?


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Network Feature Adjustment12 th bit and 13 th bit: Whether share the same BSC or MSC.

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

serving cell?NoYes

Both 12 th and 13 th set to 0

12 th set to 113 th set to 0

Is [Co-BSC/MSC Adj](s)yes?

Yes

No

Co-BSC?

Co-MSC?

No

Yes


No

Yes

Turn off12 th &13 th bit



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Data Configuration of Co-BSC&MSC


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Cell A

Cell B

Cell CCell E

Cell F

Cell S

13 12 11 10 9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

E


Question(The 12 th,13 th Bit)

Cell D

BSC1

BSC2

MSC


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The 14 th bit: [Inter-layer HO Threshold/Hysteresis] adjustment bit.


16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

The 15 th/16 th bits are reserved

Yes

serving cell?

set to 0

NoYes

Bit 14 th set to 1, and bit5 th ~13 th are turned off

set to 0

Yes

RX_LEV_DL (s) >= [Inter-layer HOThreshold](s) [Inter-layer HO Hysteresis](s)?

RX_LEV_DL (n) >= [Inter-layer HOThreshold](n) + [Adjacent Cell Inter-layer HO

Hysteresis](s->n)?

No No

D t C fi ti f L HO


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Data Configuration of Layer HOThreshold Adjustment

D t C fi ti f L HO


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Data Configuration of Layer HOThreshold Adjustment


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-73dBm

Cell A

Cell B

Cell CCell E

Cell F

Cell S

Cell D

-90dBm

-80dBm

-83dBm

-75dBm

-70dBm

-85dBm


[Inter-layer HO Threshold](s&n) 25

[Inter-layer HO Hysteresis](s&n) 3dB

Serving cells threshold -88dBm

Neighbor cells threshold -82dBm

Question(The 14 th Bit)

14 13 12 11 10 9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

EGiven condition:

Then we can get:


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General HO Process


MS Goes into

Dedicated Mode


MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO


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No DL MR HO

Serving Cell Neighboring Cell

When the quality of Um interface become worse and worse, it isfor the worse uplink quality that MS can not deliver downlink MR,

while the downlink quality is not bad enough for MS to receive the

downlink message normally.

Baduplink

quality


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Position of No DL MR HO



Measure and MeasurementResult Report

1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO

No DL MR HO


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No DL MR HO

Begin

Report 1 DL MR at least?

[No Dl Mr. HOAllowed](s) Yes ?

=[No Dl Mr.Ul Qual

HO Limit](s)?

Yes

Only onecadidate cell?

Within Penalty Time

Yes

No

No

Yes

Yes

Yes

No

[Intracell HO Allowed](s)?

Yes

No

No


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Data Configuration of No DL MR HO


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TA(Time Advance) HO


[TA Threshold](s)

Time

TA(s)

HandoverTriggering

[TA Threshold](n)

or

Handover Triggering ZoneTA(n)


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Data Configuration of TA HO


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TA=2

Cell A

Cell B

Cell CCell E

Cell F

Cell S

Cell D

TA=3

TA=5

TA=4

TA=3

TA=0

TA=1

Question(TA HO)

Candidate cell list high >low F S E D B C A

Which cell is the target cell?


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Interference Handover

Lev_Thr

Rx_Qual

RX_Lev

Qual_Thr

InterferenceOrigin


Handover TriggeringZone


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Interference HOBegin

UL or DL receiving

Quality( s )>=A?

[Interference HOAllowed] Yes ?

serving cell?

Select the cell with thehighest priority in the

cadidate cell list

Rx_Level( n )>=[Inter-layer HO Threshold]( n ) +

[Inter-layer HO Hysteresis]( s->n )?

End

No

No

No

No Yes

None AMR FR:A = RXQUALn, 1


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Data Configuration of Interference HO


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Question(Interference HO)

1 Suppose: Current call is a normal FR call, data is configured be default

as before

[Interference HO Allowed]=Yes,

DL receiving level=-70dBm

DL receiving quality=5,

Question: Interference HO will be triggered or not?

2 If the call is AMR FR call, all the other is still the same, what will

happen?


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Question(Interference HO)

Candidate cell list high >low S F E D B C A

Suppose: Cell Ss quality is 7

1) [Intracell HO Allowed](s) is Yeswhich is the target cell?

2) [Intracell HO Allowed](s) is No

which is the target cell?

Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

-85dBm

-80dBm

-90dBm

-83dBm

-75dBm

-73dBm

-70dBm

[Inter-layer HO Threshold](s/n) 25[Inter-layer HO Hysteresis](s/n) 3dB

Neighbor cell threshold -82dBm


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BQ(Bad Quality) HO

Begin

Is [BQ HO Allowed] Yes ? Any neighbourexcluding serving

cell exist ?

Select the cell with the/nexthighest priority

Yes

No

End

No

No

Yes

No

Yes

UL_Rx_Q( s )>=[UL Qual.

Threshold](s) or DL _ Rx _ Q(s )>=[DL Qual. Threshold](s)?

RX_LEV_DL ( n) > RX_LEV_DL ( s )+ [Inter-cell HO hysteresis( s->n )]

-[BQ HO Margin( s->n )] ?

[Intracell HO Allowed](s) yes & cell not punished?

Suitable cellexist?

TriggerBQ handover

Yes

YesNo

No

Mor than one neighbour? No

Yes


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Data Configuration of BQ HO


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h d l d


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Two single band cells which are configured as bi-directional neighbor cell

relationship can be configured as enhanced dual band cell to each other.

Purpose

During the procedure of channel assignment and handover, the two single

band cells can share their resource.

Assign the channel with low load in UL to MS preferentially.

Make MS handover from the high load cell to the low load cell.


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Channel Assignment of Enhanced Dual Band

RX_LEV_OL>= [Incoming OL Subcell HO level Threshold(dB)](o) andRX_LEV_UL RX_LEV (n) >[Distance Between Boundaries of UL and OL Subcells(dB)]Attention:RX_LEV (n): RX_LEV of the strongest neighboring cell which has the same frequency band and layerwith underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBmIf [ATCBHoSwitch] is [Close], the second condition is turn off.

A:

TCH assignment (SDCCH channel in UL)Begin

from UL

[UL Subcell AssignmentOptimization (u) ?

Cell load of UL >[UL Subcell General

Overload Threshold(%)](u)?

Yes

A Yes

No

Any idle TCHAvailable in OL?

Assign TCHin OL

Yes

No

Yes

Assign TCH in ULor direct retry identification

or queuing

No

No

Data Configuration of Channel


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ata Co gu at o o C a e Assignment

Data Configuration of Channel


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g Assignment

f


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Beginfrom OL

[OL Subcell AssignmentOptimization) No ?

Cell load of UL= [Incoming OL Subcell HO level Threshold(dB)] (o) andRX_LEV_UL RX_LEV (n) > [Distance Between Boundaries of UL and OL Subcells(dB)]A:

Cell load of UL>=[UL SubcellSerious Overload Threshold(%)](u)?

Begin [Load HO Allowed](u) Yes ?

Cell load of UL>=[UL SubcellGeneral Overload Threshold(%)](u)?

No

A & Satisfy P/N &not within penalty time?

TriggerUL to OL

Yes No

Adjust HO zone basingon HO step and HO period

Refresh cell loadper second

BB-C

Yes

Any MS in HO zone?

Yes

No

No

Yes

Yes No

End

Cell load of OL>=[Inner Cell Serious Overload

Threshold(%)](o)? Yes

No

Data Configuration of Enhanced Dual


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gBand HO(U O )

Data Configuration of Enhanced Dual


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gBand HO(U O )

Enhanced Dual Band HO(O U )


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Enhanced Dual Band HO(O U )Triggering condition for TCH HO from OL to UL for moving

RX_LEV_OL


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Band HO(O U )


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Triggering condition for TCH Load HO from OL to UL for low load in UL



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Enhanced Dual Band HO(O U )Triggering condition for TCH Load HO from OL to UL for low load in UL

HO zone : [Outgoing OL Subcell HO Level Threshold(dB)](o) ~ -47dBmHO step : [Step Length of OL Subcell Load HO(dB)](o)A: RX_LEV_UL >= Inter-layer HO Threshold(u) + Inter-layer HO Hysteresis(o->u)

Begin

[Load HO of OL Subcellto UL Subcell ](o) Yes ?

Cell load of UL


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General HO Process


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General HO Process




MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO

Load HO


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Load HOHandover triggering zone

[Load HO Threshold]

Time

Load of Serving Cell

[Load Req. on Candidate Cell]

Load of Neighboring Cell

Congested Cell

Congested Cell

Congested CellNormal Cell

Normal CellNormal Cell

Normal Cell

Load HO


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Load HO

As load HO may trigger several HOs, we need to consider

the CPU load (system flow level) before triggering it. In

addition, load HO is executed step by step, that is, the edge

HO thrsh. raises according to certain step and period and

will stop when out of the Load HO Zone.

Load HO


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Load HO

Congested Cell

Normal Cell

Normal Cell

Normal Cell

Load HO


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Begin

[Load HO Allowed] (s) Yes ?

BSC internal cell?

Select the cell with the highestpriority in the cadidate cell list

End

No

No

Yes

No Yes

Yes

Current system flux=[Load HO Threshold](s)?

Yes

No

Yes

Load HO timerT overflow?

Yes

Step Period

T )1( [Load HO Bandwidth](s)

B

Yes

serving cell?

No

No

B: [Edge H O_DL_RX_LEV Threshod](s)= [Inter-layer HO Threshold](n) +

[Inter-layer HO Hysteresis](s->n)D: load(n)< Load Req. on Candidate Cell(n)Step: [Load HO Step Level](s)Period: [Load HO Step Period](s)

CNo

A=

No

Yes

Load HO timerT begin?

No

NoStar timer T

Period Step

T AStep )1Bandwidth]HO[Load

(0 Bandwidth]HO[LoadA T

Yes

A=

Data Configuration of Load HO


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Data Configuration of Load HO


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Edge Handover


108/162


Edge HandoverHandoverTriggering

P / N


P: Valid TimeN : Watch Tim e

RX_LEV Thr

Time

RX_Lev


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Data Configuration of Edge HO


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Should be lower than the[Outgoing OLSubcell HO Level Threshold(dB)] in enhance

dual band data table

[Edge HO UL/DL RX-LEVThreshold]


111/162




112/162

MS Fast-Moving Handover


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MS Fast Moving Handover

Handover

Triggering

Time Threshold

Umbrella Cell

Time

P/NP: Valid CellsN: Watch Cells

1 1 2 3

Micro Cell

Cells Number

MS Fast-Moving Handover


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MS Fast Moving HandoverBegin

[MS Fast Moving HOAllowed](s) Yes ?

End

No

Yes

Yes

the servingcell on layer 4?

Satisfy P / N rule?No Select the neighbor cell with the highest priority &

on the 4th layer & satisfy RX_LEV(n)>= [Inter-layerHO threshold](n) + [Inter-layer HO hysterisis](s->n)

Any cell satisfy thecondition above?

Trigger MS fast-moving handover

No

Yes

Refresh timer(s)

No

Yes

Data Configuration of MS Fast-movingH d


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Handover


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Layer HO


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y

Neighboring CellServing Cell

GSM900 CellLay 3

GSM1800 CellLay 2

Layer HO


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Begin

[Level HOAllowed](s) Yes ?

End

No

Yes

Yes

Any neighbor cell exit?

16 bit value( n )n)

Yes

Identify the next cell

No

y

Data Configuration of Layer HO


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g y



120/162


g y



121/162


g y

PBGT HO


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PBGT HOThreshold

Time

Path Loss (dB)

126dB 119dB

5

126 -119 =7dB>5dB

HandoverTriggering

P / N P: Valid Time

N : Watch Time

PBGT HO


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Begin[PBGT HO

Allowed] (s)Yes ?

End

No

Yescurrent channel

signaling channel?

Satisfy P / N rule?

No

Yes

Search nextneighborcell

layer(n)=layer(s)&level(n)=level(s)?

Path loss (s) Path loss (n)>[PBGT HO Threshold](s->n)

Refresh timer(s)

TriggerPBGT HO

Yes

No

Yes

No

Yes

No

NOTES: whichever the greater of the[inter-cell HO hysteresis] and

[PBGT HO threshold], that value will be

used in the PBGT HO.

Data Configuration of PBGT HO


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g

Data Configuration of PBGT HO


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g

Concentric Cell


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Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved.Page135

Purposes

Maximize coverage area

Reduce interference and improve frequency reuse density

Construction methods

Different combiner lossDifferent propagation loss

Modify the transmission power of TRX, the down tilt of antennas, etc.

By HO parameters

Overlaid

Underlaid

Classification and HO Judgment ofC t i C ll


127/162


Concentric Cell

Receiving level

Time advance

Quality

Receiving level

Time advance

Quality

ATCB

Cell load of underlaid

Normal concentric cell Enhance concentric cell

Data Configuration of Concentric Cell


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Normal Concentric Cell HO


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Division of underlaid and overlaid is decided by MS downlink

receive level ,TA value and quality.

underlaid

overlaid

Receiving Level Threshold

Receiving Level Hysteresis

Receiving Qaulityl Threshold

TA Threshold

TA Hysteresis

Normal Concentric Cell HO


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U to O O to U

Normal Concentric Cell HO(O U )


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Flow for TCH HO from overlaid to underlaid

Begin within Penalty Time End Yes

No

[RX_LEV for UOHO Allowed] Yes?

Yes

[OL to UL HOAllowed] Yes ?

No Yes

[RX_QUAL for UOHO Allowed] Yes?

Yes

Rx_Dl_Quality>=[RX_QUAL Treshold]? Current TA>=[TA Threshold]+[TA Hysteresis]?

[TA for UO HOAllowed] Yes?

Trigger OL to UL

P/N rule?

Yes Yes

Yes

Yes

No

NoNo

No No No

End

Rx_Dl_Level


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Criterion for TCH HO from underlaid to overlaid

Begin

With Penalty Time ? End Yes

No

Current TA=[RX_LEV Threshold] +

[RX_LEV Hysteresis]No


Rx_Dl_Qual


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Concentric Cell HO

Enhance Concentric Cell HO


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Division of underlaid and overlaid is decided by MS downlink

receive level, quality, TA value and cell load of underlaid.

underlaid

overlaid

U to O HO Receiving Level Threshold

O to U HO Receiving Level Hysteresis

Receiving Qaulityl Threshold

TA Threshold

TA Hysteresis

Enhance Concentric Cell HO


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Classification of TCH HO in enhance concentric cell HO

O to Ufor low load in U

U to Ofor high load in U

O to Ufor moving

Enhance Concentric Cell HO(U O )Flow for TCH HO from underlaid to overlaid for high load in UL


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A: RX_LEV_UL RX_LEV (n) >[Distance Between Boundaries of UL and OL Subcells(dB)]RX_LEV (n): RX_LEV of the strongest neighboring cell which has the same frequency band and layerwith underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBm

Begin

Within Penalty Time ? End Yes

No

Current TA[UtoO HOReceived Level Threshold]

No

A Yes

No


Rx_Dl_Qual=[En Iuo OutCell Serious OverLoad Thred]?

Begin[UtoO Traffice

HO Allowed] Yes ?

Cell load of UL>=[En Iuo OutCell General OverLoad Thred]?

TriggerUL to OL

Yes No

Adjust HO zone basingon HO step and HO period

Refresh cell loadper second

B(B-1)/second

YesB=[Underlay HO Step Period(s)]HO step : [Underlay HO Step Level]HO period: B-x or BHO zone : begin from -47dBm

Any MS in HO zone?

Yes

No

Yes

No

End

No

Enhance Concentric Cell HO(O U )


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Flow for TCH HO from overlaid to underlaid for low load in underlaid

HO period: [En Iuo in Cell Load Classification HO Period]HO step : [En Iuo in Cell Load Classification HO Step]HO zone : begin from [OtoU HO Received Level Threshold] to -47dBm

Begin[[OL to UL HOAllowed] Yes ?

Cell load of UL


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Flow for TCH HO from overlaid to underlaid for moving

No

Begin With Penalty Time ? End Yes

No

[ATCBHoSwitch]Open?

No[RX_LEV for UO

HO Allowed] Yes?

Rx_Dl_Level[RX_QUAL Treshold]? Current TA>[TA Threshold]+[TA Hysteresis]?

[TA for UO HO

Allowed] Yes?

Trigger OL to UL

P/N rule?

Select the underlaid subcell orthe neighbour cell with thehighst priority in 16 bits list

Yes Yes Yes

Yes

No

Yes

No No

No No

NoEnd

A: RX_LEV_UL RX_LEV (n) < [Distance Between Boundaries of UL and OL Subcells(dB)] [Distance Hysteresis Between Boundaries of UL and OL Subcells(dB)]

Data Configuration of EnhanceConcentric Cell HO


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Concentric Cell HO



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Concentric Cell HO



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Concentric Cell HO



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Concentric Cell HO



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Concentric Cell HO



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Concentric Cell HO

Channel Assignment strategies ofConcentric Cell


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Channel Assignment Strategies of Concentric Cell

ImmediateAssignment Assignment

Intra-BSCInter-cell

Handover

IncomingCell

Handover

Immediate Assignment


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The preferred SDCCH channel in two layers is controlled by

parameter TA pref. Of Imme - Assign Allowed

If "No", system prefers the channel in Underlaid subcell

If Yes", system prefers the channel according to in Channel

Request message

TA smallerTA bigger

Data Configuration of Immediate Assignment


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g

Assignment


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Preferred assignment in the overlay or underlay cell

Assign the channel of overlay or underlay cell according

to the Rx_level and TA in the measurement report

TA smaller andRx level higher

g

Data Configuration of Assignment


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Intra-BSC Inter-Cell Handover


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In the case of intra-BSC inter-cell handover, the MS can be

handed over to the underlay or overlay cell first.

If System Optimization is selected, the preferred assignment is

conducted according to the level value in the measurement report.

overlaidUnderlaid

OverlaidAccording to the Rx-level

Data Configuration of Intra-BSC Inter-Cell Handover


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Inter-BSC Handover


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For the inter-BSC Handover, if the target cell is concentric cell , the

channel of underlay cell should be assigned first.

overlaid

Underlaid

Overlaid

BSC1 BSC2

Assign underlaid first

Data Configuration of Inter-BSC Inter-Cell Handover


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AMR Handover Flow


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Begin

Intracell F-H HOAllowed Yes ?

Yes

Is current channelTCH & version3?

No

A: Cell load > [AMR TCH/H PriorCell Load Threshold]

During [Penalty Timeafter AMR TCHF-H HOFail(s)]?

Yes

Yes

current channel is FR

Satisfy P/N rule? Trigger internal cellAMR handover

Yes

NoEnd

RQI/2 >[F2H HO th] & A RQI/2


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Data Configuration of AMR HO


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General HO Process


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Measurement Report Preprocessing2

Handover Judgment3


Handover Implementation


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Begin

[Power Forecast Allowed (s) Yes ?

BSC predict power

YesNo

BSC send HOCommand to MS

HO execute

MS uses the highestpower to access For MS

MS will use this predictpower to access thetarget cell

Data Configuration of HandoverImplementation(MS)


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Summary


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In this course, we have learned:

Classification of HO

HO general procedure

HO judgment algorithm

HO implementation process

HO data configuration


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3- OMO133030 BSC6900 GSM V9R13 Handover Algorithm I ISSUE 1.02.ppt

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