omo131020 bsc6900 gsm v9r11r12r13 handover algorithm i issue1.11

8/13/2019 Omo131020 Bsc6900 Gsm v9r11r12r13 Handover Algorithm i Issue1.11

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Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page2

Foreword

Handover is a key technology of mobile communication system

and make continued conversation possible.

Handover algorithm in Huawei product is flexible and powerful.




Objectives

Upon completion of this course, you will be able to:

Outline the types of handover

Master handover judgment flow

Understand algorithm of different handovers

Explain HO data configuration




Contents

1. Introduction of Handover

2. HO Algorithm Ⅰ Process




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




Classification by Reason

No DL MR Emergency HO

Timing Advance (TA) HO

Interference HO

Rx_Level_Drop HO

Bad Quality (BQ) HO

Emergency HO

Enhanced Dual Band HO

Load HO

Normal HO

1

2

3

4

Classification by

ReasonEDGE HO

PBGT HO

Layer HO

MS Fast Moving HOConcentric Cell HO

AMR HO




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 4Case 5

MSC

BSC

BTS

BSC BSC

MSC

BTS BTSBTS

BTS

NSS Network




Classification by Equipment and

Channel

SDCCH → TCH

(Direct Retry)

SDCCH → SDCCH

Intra – Cell HO

Inter – Cell HO

Intra – BSC HO

Intra – MSC HO

Inter – MSC HO

TCH → TCH




Contents

1. Introduction of Handover

2. HO Algorithm Process




Contents

2. HO Algorithm Ⅰ Process

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




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




General HO Process





Handover Judgment3





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




Measurement Report




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




General HO Process



Measurement Report Preprocessing

Handover Judgment3



2




MR Preprocessing

MR Preprocessing

Interpolation

Recover the lost

measurement report

Filtering

Smooth the instantaneous

fading point




MR Interpolation

MR

MR

No. n

No. n+4

MR

MR MR

Missing by

some reasons




MR Filtering

MR

MR MR

MR

MR

Filter----Average several

consecutive MRs

MR




Data Configuration of MR

Preprocessing





Preprocessing




General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode

Measure and MeasurementResult Report

1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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




Penalty Processing

Intra-cellHO

HO FailsEmergency

(TA&BQ)HO

MS Fast

Moving

HO

Concentric

Cell HO

Penalty

Punish on

the target

cell

Punish on the

original cell

Punish on other

high priority layercells

AMR HO

Fails




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 by

signal level valueCell A

Cell D

HO fails X

-80dBm

-75dBm

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




Data Configuration of Penalty for

Handover Failure





Handover Failure




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 to

cell D for BQ or TA, so original cell A

should be punished-80dBm

-75dBm

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





Emergency Handover




Back? No way!

Umbrella

Micro cell

Penalty for MS Fast-moving Handover

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

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

HO.




Data Configuration of Penalty for MS

Fast-moving Handover




Underlaid

Overlaid Do not attempt

again duringpenalty time

after one failedHO(O<->U)!

Penalty for Concentric Cell

A new concentric cell HO is prohibited within a penalty timeafter a concentric cell HO failure.

Do notattempt again

after N failedHO(U->O)!





Concentric Cell




Underlaid

Overlaid

Do notattempt backtoo fast!

Penalty for Enhanced Concentric Cell

A new UO HO is prohibited within a penalty time after

a OU HO is performed successfully.





Enhanced Concentric Cell




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.

T

R

X1

T

R

X

2

T

R

X

3

T

R

X

4

T

R

X

5





Intra-cell HO




Data Configuration of Penalty for AMR

FRHR Handover Failure




General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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




Ranking Processing

M rule

K rule

Basic ranking

16 bits ranking

Network feature adjustment

The ranking result: target cell selection of handover




M Rule

Begin

Finish to allneighbor cells?

No

Yes

the cell overload ? Yes

RX_LEV_DL(n) < [Min DL Power

on 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 from

the cell list

Yes

No

No

No

No

End

For service cell:

Min Access Level Offset=0

M rule will remove the cells fromthe candidate cell list whichunable to fulfill the conditionaccording to the flow.

Yes




Data Configuration of M Rule




Network Feature Adjustment

After network feature adjustment, 16 bits value is calculated forevery candidate cells.

The smaller the value, the higher the handover priority and

ranking in the candidate cell list, and it is possible to be the

target cell.





The 1st

~3rd

bits

The 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 cell

according 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




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 1st~3rd Bits)





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




Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

-85dBm

-80dBm

-90dBm

-83dBm

-75dBm

-95dBm

-70dBm4 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 4th Bit)

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




Data Configuration of Inter-cell HO Hysteresis





The 5th

~10th

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.

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

Player (0~3) Plevel (0~15)

Player_level (0~63)

level layer level layer P P P 16 _




Hierarchical Cell Structure

GSM900 Cell

Micro Cell

Umbrella Cell GSM 900

GSM1800 GSM1800GSM1800

GSM 900

GSM900GSM900

GSM1800GSM1800

GSM1800 Cell

GSM 900

GSM900GSM900

GSM1800GSM1800

Layer 4

（low）

Layer 3

Layer 2

Layer 1

（high）

D t C fi ti f C ll Hi hi l




Data Configuration of Cell Hierarchical

Network Structure




Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

L3 P1

L3 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 list（high－>low）

Question(The 5th~10th Bits)





The 11

th

bit: The bit value is decided by cell-load-sharingcriterion.

This bit is affected by 14th 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 11th bit is

turned off

serving cell?

set to 0

No Yes

Cell load >= [Load

HO Threshold](s)?

set to 1 set to 1

cell load >=[ Load Req.

on Candidate Cell](n)?

set to 0

Yes

No

Yes

No

No




Data Configuration of Cell-load-sharing




Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

1

1

1

0

9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

E


Question(The 11th Bit)Suppose：system flow<[System Flux Threshold for Load HO](s) and

[Load HO Allowed](s) is “Yes”

Normal cell with few traffic

cell load(n) < [Load Req. on Candidate Cell](n)

Abmornal cell with heavy traffic

non-serving cell: load(n) >＝ [Load Req. on Candidate Cell](n)

serving cell: load(s) >= [Load HO Threshold](s)?





12th bit and 13th 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 12th and 13th set to 0

12th set to 113th set to 0

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

Yes

No

Co-BSC?

Co-MSC?

No

Yes


No

Yes

Turn off

12th &13th bit





Data Configuration of Co-BSC&MSC




Cell A

Cell B

Cell CCell E

Cell F

Cell S

1

3

1

2

1

1

1

0

9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

E


Question(The 12th,13th Bit)

Cell D

BSC1

BSC2

MSC




The 14th 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 15th/16th bits are reserved

Yes

serving cell?

set to 0

NoYes

Bit 14th set to 1, and bit

5th ~13th are turned off

set to 0

Yes

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

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

Hysteresis](s->n)?

No No

Data Configuration of Layer HO





Threshold Adjustment





-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 cell’s threshold：-88dBm

Neighbor cell’s threshold：-82dBm

Question(The 14th Bit)

1

4

1

3

1

2

1

1

1

0

9 8 7 6 5 4 3 2 1 Cell

F

D

B

C

S

A

EGiven condition:

Then we can get:




General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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




No DL MR HO

Serving Cell Neighboring Cell

When the quality of Um interface become worse and worse, itis for 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.

Baduplinkquality




Position of No DL MR HO

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode

Measure and Measurement

Result Report1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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

Handover Due to No Downlink





Measurement Report

Start

At least one

downlink MR is received?

No Dl Mr.HO

Allowed](s) is set to Yes ?

The numberof lost downlink MRs Cons.No

Dl Mr.HO AllowedLimit (s)?

Add handover cause

and check others

Yes

No

Check other

handover types

No

No

No

No downlink

information is in the current

MR?

Yes

Yes

Yes

No

Remove the serving cell from the

candidate cell list and check the cell with a

high priority for handover

All the candidate

cells are checked?

RXLEV(n) > RXLEV(s) +

Inter-cell Handover Hysteresis

(s->n)-BQ HO Margin(s->n)

Yes

No

Yes

No

The lost MR. number meetP/N rule?(For GBSS13.0)

Yes

Uplink quality

No Dl Mr.Ul Qual HO

Limit (s)

Yes

No Meet the P/N rule?

Check other

handover types






Measurement Report – Data Configuration





These two parameters are available from GBSS13.0.







TA(Time Advance) HO


[TA Threshold](s)

Time

TA(s)

Handover

Triggering

[TA Threshold](n)

or

Handover Triggering Zone

TA(n)

TA(Ti Ad ) HO




TA(Time Advance) HO

TriggerTA handover

Begin

The actual TA >= [TA Threshold](s)?

[TA HO Allowed]

Yes ?

Any neighbour cell

exist?

serving cell?

Select the cell with the

highest priority in the

cadidate cell list

Suitable cell

exist?

Yes

No

End

No

No

Yes Yes

No

No

Yes

Yes

Yes

No

[TA Threshold]

(n,in the same BTS)

<= [TA Threshold](s)

D t C fi ti f TA HO




Data Configuration of TA HO



I t f H d




Interference Handover

Lev_Thr

Rx_Qual

RX_Lev

Qual_Thr

InterferenceOrigin


Handover TriggeringZone

I t f HO




Interference HO

Begin

UL or DL receiving

Quality(s)>=A?

[Interference HO

Allowed] Yes ?

Any neighbour cell

exist?

serving cell?



cadidate cell list

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

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

Yes

No

End

No

No

Yes No

No Yes

None AMR FR/HR:

A = RXQUALn, 1<=n<=12

AMR FR/HR:

A = RXQUAL1, n=1;

A = RXQUALn + RXLEVoff, 2<=n<=12

[Intracell HO Allowed](s) yes

& cell not punished?

Any suitable cell

exist?

Trigger

interference handover

No

Yes

Yes

Yes

Yes

No

D t C fi ti f I t f HO




Data Configuration of Interference HOConfigured Value

(-110dBm)

Receiving Level (dBm) Receiving Quality

RXQUAL1 <=30 (-∞, -80] 60

RXQUAL2 =31 =-79 50

RXQUAL3 32~35 [-78, -75] 49

RXQUAL4 36~38 [-74, -72] 48

RXQUAL5 39~41 [-71, -69] 47

RXQUAL6 42~45 [-68, -65] 46

RXQUAL7 46~48 [-64, -62] 45

RXQUAL8 49~52 [-61, -58] 44

RXQUAL9 53~55 [-57, -55] 43

RXQUAL10 56~58 [-54, -52] 42

RXQUAL11 59~62 [-51, -48] 41

RXQUAL12 >=63 [-47, + ∞) 40

Default

ValuePar.

Par.Name





Data Configuration of Interference HO





Data Configuration of Interference HO

Q ti (I t f HO)




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?

Q estion(Interference HO)




Question(Interference HO)

Candidate cell list（high－

>low） S F E D B C A

Suppose: Cell S’s quality is 7

1) [Intracell HO Allowed](s) is Yes，

which is the target cell?

2) [Intracell HO Allowed](s) is No，


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

Rx Level Drop HO




Rx_Level_Drop HO

Rx Level Drop HO




Rx_Level_Drop HO

Begin

Satisfy the Formula&

The latest RX_LEV_UL(s) <

[Edge HO UL RX_LEV Threshold](s)?

[Rx_Level_Drop HO

Allowed] Yes ?

Any neighbour cell

exist?

serving cell?



cadidate cell list

Yes

No

End

No

No

Yes

No Yes

Formula:

Is priority higher than

serving cell?

Trigger

Rx_Level_Drop handover

Yes

Yes

B X A X A X A X A

X A X A X A X A

88776655

44332211

10101010

10101010

EndNo

D t C fi ti f R L l D HO




Data Configuration of Rx_Level_Drop HO

Data Config ration of R Le el Drop HO




Data Configuration of Rx_Level_Drop HO

BQ(Bad Quality) HO




BQ(Bad Quality) HO

Begin

Is [BQ HO Allowed]

Yes ?

Any neighbour cell

exist?

serving cell?



cadidate cell list

Yes

No

End

No

No

Yes

No Yes

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?

Trigger

BQ handover

Yes

Yes

Yes

No

No

No

Data Configuration of BQ HO





General HO Process




General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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






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.

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 layer

with underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBm

If [ATCBHoSwitch] is [Close], the second condition is turn off.

A:

TCH assignment (SDCCH channel in UL)

Beginfrom UL

[UL Subcell AssignmentOptimization(u) ?

Cell load of UL >

[UL Subcell General

Overload Threshold(%)](u)?

Yes

A

Yes

No

Any idle TCH

Available in OL?

Assign TCH

in OL

Yes

No

Yes

Assign TCH in UL

or direct retry identification

or queuing

No

No

Data Configuration of Channel




Assignment

Data Configuration of Channel




Assignment





Begin

from OL

[OL Subcell AssignmentOptimization) No ?

Cell load of UL<

[UL Subcell Lower

Load Threshold](u)?

Yes

Yes

No

Assign TCH

in UL

Any idle TCH

Available in UL?

Assign TCH

in UL

Any idle TCH

Available in OL?

Assign TCH

in OL

Yes No

Yes

Assign TCH in OL

or direct retry identificationor queuing

No

No

TCH assignment (SDCCH channel in OL)






Classification of TCH HO in enhanced dual band HO

OL to UL

for low load in UL

UL to OL

for high load in ULand moving

OL to UL for moving

Enhanced Dual Band HO(UO )




Enhanced Dual Band HO(UO )

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

UL

Enhanced Dual Band HO(UO ) Triggering condition for TCH Load HO from UL to OL for high load in




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

UL

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)]

A:

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

Begin[Load HO From UL Subcell

to OL Subcell Allowed](u) Yes ?

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

and

No

Satisfy P/N?

Trigger

UL to OL

Yes No

Adjust HO zone basing

on HO step and HO period

BB-C

Yes

Any MS in HO zone?

Yes

No

Yes

Yes

No

End

Cell load of OL<=[Inner Cell Serious Overload Threshold(%)](o)?

Yes Yes

No

Is the system traffic of current cell<＝[Allowed Flow Control Level of UL

and OL Subcell HO]?

RX_LEV_OL >= [Incoming OL Subcell

HO level Threshold(dB)] (o)?

A

No

No

No

Yes

Data Configuration of Enhanced Dual




Band HO(UO )





Band HO(UO )

Enhanced Dual Band HO(OU )





Triggering condition for TCH HO from OL to UL for moving

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


A:

Satisfy P/N?

Begin

AYes

End

Trigger

OL to UL

Yes

Select Neighbor cell

with the highest priority

No

YesNo

[Inner Cell EDGE HOEnable](o) Yes ?

RX_LEV_OL <[Outgoing OL Subcell HO levelThreshold(dB)](o)

Yes

No

No

The target cell could be underlaid

subcell or normal neighboring cell


B d HO(OU )




Band HO(OU )






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






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) ~ -47dBm

HO 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 Enable](o) Yes ?

Cell load of UL <[UL Subcell

Lower Load Threshold(%)](u)?

Yes

No

End

Satisfy P/N?

Yes

No

The object cell must be

the underlaid subcell

and satisfy condition A

Any MS in HO zone?

Yes

Trigger OL to UL

No

YesNo



Is the system traffic of currentcel<=[Allowed Flow Control Level

of UL and OL Subcell HO]?

RX_LEV_OL >= [Outgoing OL SubcellHO level Threshold(dB)] (o)?

No

Yes

Yes

No


B d HO(OU )




Band HO(OU )

General HO Process




General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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




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




oad O

As load HO may trigger several HOs, the CPU load

(system flow level) must be considered before the

feature is triggered.

In addition, load HO is executed step by step, that is,

from the edge HO thrsh. raises according to certain step

and period.

The process will be stopped when the Load HO Zone is

reached the threshold.

Load HO




Load HO

Congested Cell

Normal Cell

Normal Cell

Normal Cell

Load HO




Begin

[Load HO Allowed] (s)

Yes ?

BSC internal cell?

Select the cell with the highest

priority in the cadidate cell list

End

No

No

Yes

No Yes

Yes

Current system flux<=[System Flux Threshold

for Load HO](s)?

C & D

Suitable cellexist?

Trigger

load handover

Yes

Yes

Yes

EndNo

Load of service cell >=[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 HO_DL_RX_LEV Threshod](s)<DL_RX_Lev(s)

< [Edge HO_DL_RX_LEV Threshod](s)+A

C: RX_LEV (n)>= [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

No

Star timer T

Period Step

T AStep )1Bandwidth]HO[Load

(0 Bandwidth]HO[LoadA T

Yes

A=

Data Configuration of Load HO




g

General HO Process




MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop 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

Edge Handover




g

HandoverTriggering

P/ N


P: Valid TimeN: Watch Time

RX_LEV Thr

Time

RX_Lev



Data Configuration of Edge HO




g g

Should be lower than the[Outgoing OL

Subcell HO Level Threshold(dB)] in enhance

dual band data table

[Edge HO UL/DL RX-LEV

Threshold]<[UL/DL RX_LEV Lower

Threshold] in HWII/III power control table





g g





g g

MS Fast-Moving Handover




g

TimeThreshold

Fast-Moving

Handover Triggering

2 311

P/NP: Watch CellsN: Valid Cells

Time

Cells Number

Umbrella Cell

Micro Cell

MS Fast-Moving Handover




Begin

[MS Fast Moving HO

Allowed](s) Yes ?

End

No

Yes

Yes

the serving

cell 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-layer

HO threshold](n) + [Inter-layer HO hysterisis](s->n)

Any cell satisfy the

condition above?

Trigger MS fast-

moving handover

No

Yes

Refresh timer(s)

No

Yes

Data Configuration of MS Fast-moving

Handover




Handover

Layer HO



Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved.Page141

Neighboring CellServing Cell

GSM900 Cell

Lay 3 GSM1800 Cell

Lay 2

Layer HO




Begin

[Level HO

Allowed](s) Yes ?

End

No

Yes

Yes

Any neighbor cell exit?

16 bit value(n)<16 bit value(s)?

A & ( layer(n)< layer(s)or level(n)<level(s) )?

Satisfy P/N rule(n)?

No

Trigger

layer handover

Yes

No

Yes

No

A: RX_LEV(n)>= [Inter-layer HO threshold](n)

+ [Adjacent Cell Inter-layer HO Hysteresis](s->n)

Yes

Identify the next cell

No





PBGT HOHandover





PBGT HOThreshold

Time

Path Loss (dB)

126dB119dB

5

126-119=7dB>5dB

HandoverTriggering

P /N P: Valid Ti me

N: Watch Time

PBGT HO




Begin

[PBGT HO

Allowed] (s)Yes ?

End

No

Yes

current channelsignaling channel?

Satisfy P / N rule?

No

Yes

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

Path loss (s) – Path loss (n)>PBGT HO Threshold(s->n)

TriggerPBGT HO

Yes

No

Yes

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.

16 bit value(n)<16 bit value(s)?

Yes

Identify thenext cell

No

No

Data Configuration of PBGT HO




Data Configuration of PBGT HO




Concentric Cell




Purposes

Maximize coverage area

Reduce interference and improve frequency reuse density

Construction methods

Different combiner loss Different propagation loss

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

By HO parameters

Overlaid

Underlaid

Classification and HO Judgment of

Concentric Cell




Concentric Cell

Receiving level

Time advance

Quality

…

Receiving level

Time advance

Quality

ATCB

Cell load of underlaid

… Normal concentric cell Enhance concentric cell



Normal Concentric Cell HO




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




U to O O to U

Normal Concentric Cell HO(OU )




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 HO

Allowed] 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<=[RX_LEV thshold]-[RX_LEV Hysteresis]

No Yes

Normal Concentric Cell HO(UO )




Criterion for TCH HO from underlaid to overlaid

Begin

With Penalty Time ? End Yes

No

Current TA<=[TA Threshold]-[TA Hysteresis]?


Yes

Yes

No

No[RX_LEV for UOHO Allowed] Yes?

Rx_Dl_Level >=[RX_LEV Threshold] +

[RX_LEV Hysteresis]No


Rx_Dl_Qual<=[RX_QUAL Treshold]?

Yes

P/N rule?

Yes

No

No

No

Yes

Yes

No

[UL to OL HO

Allowed] Yes ?

End

Yes

No

Trigger UL to OL

Data Configuration of Normal

Concentric Cell HO




Co ce c Ce O


Concentric Cell HO





Concentric Cell HO




Enhance Concentric Cell HO




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




Classification of TCH HO in enhance concentric cell HO

O to U

for low load in U

U to O

for high load in U

O to U

for moving

ATCB Principle




Neighboring

cell

Rxlev(n) = -80 dBm

Rxlev(UL) = -80 dBm

Serving cell

Rxlev(n) = -82 dBm

Rxlev(UL) = -78 dBm

A call is handed overto the OL subcell

Rxlev(n) = -80 dBm

Rxlev(UL) = -80 dBm

Neighboring

cellServing cell

Rxlev(n) = -82 dBm

Rxlev(UL) = -78 dBm

A call is handed overto the OL subcell

RX_LEV (n): RX_LEV of the

strongest neighboring cell

which has the samefrequency band and layer

with underlaid subcell, but

locates in a different BTS. If

there is no such a cell, this

value is -110dBm

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




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)]



Begin

Within Penalty Time ? End Yes

No

Current TA<[TA Threshold]-[TA Hysteresis]?

[ATCBHoSwitch] Open?


Go to the user selectionflow in the next slide

Yes

Yes

No


Rx_Dl_Level>[UtoO HOReceived Level Threshold]

No

A Yes

No


Rx_Dl_Qual<[RX_QUAL Treshold]?

Yes

P/N rule? Yes

No

No

No

No

Yes

Yes

Yes

Yes

[UL to OL HOAllowed] Yes ?

End

Yes

No

Enhance Concentric Cell HO(UO )

(Con.)




( ) User selection flow from UL to OL for high load in UL

Cell load of UL>=[En Iuo Out

Cell Serious OverLoad Thred]?

Begin[UtoO Traffice

HO Allowed] Yes ?

Cell load of UL>=[En Iuo Out

Cell General OverLoad Thred]?

TriggerUL to OL

Yes No



Refresh cell load

per second

B(B-1)/second

Yes

B=[Underlay HO Step Period(s)]

HO step: [Underlay HO Step Level]

HO period: B-x or B

HO zone: begin from -47dBm

Any MS in HO zone?

Yes

No

Yes

No

End

No

Enhance Concentric Cell HO(OU )




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 HO

Allowed] Yes ?

Cell load of UL<[En Iuo Out

Cell Low Load Thred]?

No

TriggerUL to OL


on HO step and HO periodRefresh cell loadper second

Yes

Any MS in HO zone?

Yes

No

Yes

No

End

The object cell must be

the underlaid subcell

Enhance Concentric Cell HO(OU ) Flow for TCH HO from overlaid to underlaid for moving




No

Begin With Penalty Time ? End Yes

No

[ATCBHoSwitch]Open?


Rx_Dl_Level<[OtoU HOReceived Level Threshold]

A

Yes

[OL to UL HOAllowed] Yes ?

No

Yes


Yes

Rx_Dl_Qual>[RX_QUAL Treshold]? Current TA>[TA Threshold]+

[TA Hysteresis]?


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)]




The object cell could be

underlaid subcell or

normal neighboring cell

Data Configuration of Enhance

Concentric Cell HO





Concentric Cell HO



Channel Assignment strategies of

Concentric Cell




Channel Assignment Strategies of Concentric Cell

Immediate

AssignmentAssignment

Intra-BSC

Inter-cell

Handover

Incoming

Cell

Handover

Immediate Assignment




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




Assignment




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 and

Rx level higher

Data Configuration of Assignment




Intra-BSC Inter-Cell Handover




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.

overlaid

Underlaid

Overlaid

According to the Rx-level

Data Configuration of Intra-BSC Inter-

Cell Handover




Inter-BSC Handover




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




AMR Handover FlowBegin




g

Is [Intracell F-H HO

Allowed］ Yes ?

Yes

Is current channelTCH & version3?

No

A: Cell load > [AMR TCH/H Prior

Cell Load Threshold]

During [Penalty Time

after AMR TCHF-H HOFail(s)]?

Yes

Yes

current channel is FR

Satisfy P/N rule?Trigger internal cell

AMR handover

Yes

NoEnd

RQI/2 >[F2H HO th] & A RQI/2 <[H2F HO th] End

Yes Yes

NoNo

No

No

No

Yes

Data Configuration of AMR HO




Data Configuration of AMR HO




General HO Process








Handover Judgment3


Handover Implementation




Begin

Is [Power ForecastAllowed](s) Yes ?

BSC predict power

YesNo

BSC send “HO

Command” to MS

HO execute

MS uses the highestpower to access For MS

MS will use this predict

power to access the

target cell

Data Configuration of Handover

Implementation(MS)




Summary




In this course, we have learned:

Classification of HO

HO general procedure

HO judgment algorithmⅠ HO implementation process

HO data configuration

Question




Question




Please answers the following questions:

1. What’s the neighbour cell sequence basing on MS

measurement report?

2. What’s the neighbour cell sequence on BSC after 16-bit

ranking?

3. What cell is the target cell? and what’s the handover type?

Answer(The 1st~3rd Bits)




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

0 0 0 -70dBm F

0 0 1 -75dBm D

0 1 0 -80dBm B

0 1 1 -83dBm C

1 0 0 -85dBm S

1 0 1 -90dBm A

1 1 0 -95dBm E

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

Answer(The 4th Bit)




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

0 0 0 0 15dB -70dBm F

0 0 0 1 10dB -75dBm D

0 0 1 0 5dB -80dBm B

1 0 1 1 2dB -83dBm C

0 1 0 0 0 -85dBm S

1 1 0 1 －15dB -90dBm A

1 1 1 0 －10dB -95dBm E

Candidate cell list

（high－>low）

F D B C S A E

F D B S C A E

Answer(The 5th~10th Bits)




Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

L3 P1

L3 P1

L2 P1

L2 P5

L1 P3

L3 P4

L2 P1

1

0

9 8 7 6 5 4 3 2 1 Cell

0 1 0 0 0 0 0 0 0 0 F

0 0 0 0 1 0 0 0 0 1 D

1 0 0 0 0 0 0 0 1 0 B

0 1 0 1 0 0 1 0 1 1 C

1 0 0 0 0 0 0 1 0 0 S

0 1 0 0 0 0 1 1 0 1 A

1 0 0 0 1 1 1 1 1 0 E

Candidate cell list

（high－>low）

F D B C S A E

F D B S C A E

D F A C B S E

Answer(The 11th Bit)Suppose：system flow<[System Flux Threshold for Load HO](s) and [Load




Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

Cell S

1

1

1

0

9 8 7 6 5 4 3 2 1 Cell

0 1 0 0 0 0 1 0 0 0 0 F

0 0 1 0 0 1 1 0 0 0 1 D

0 1 1 0 0 0 1 0 0 1 0 B

1 1 0 0 1 0 1 1 0 1 1 C

1 1 1 0 0 0 1 0 1 0 0 S

1 1 0 0 0 0 1 1 1 0 1 A

1 1 1 0 1 0 0 1 1 1 0 E

Candidate cell list

（high－>low）

F D B C S A E

F D B S C A E

D F A C B S E

D F B A C S E

HO Allowed](s) is “Yes”

Normal cell with few traffic

cell load(n) < [Load Req. on Candidate Cell](n)

Abmornal cell with heavy traffic

non-serving cell: load(n) >＝ [Load Req. on Candidate Cell](n)

serving cell: load(s) >= [Load HO Threshold](s)?

1 1 1 1 9 8 7 6 5 4 3 2 1 C ll

Answer(The 12th,13th Bit)




Cell A

Cell B

Cell CCell E

Cell F

Cell S

1

3

1

2

1

1

1

0

9 8 7 6 5 4 3 2 1 Cell

0 0 0 1 0 0 0 0 1 0 0 0 0 F

0 1 0 0 1 0 0 1 1 0 0 0 1 D

0 1 0 1 1 0 0 0 1 0 0 1 0 B

0 1 1 1 0 0 1 0 1 1 0 1 1 C

0 0 1 1 1 0 0 0 1 0 1 0 0 S

0 0 1 1 0 0 0 0 1 1 1 0 1 A

0 0 1 1 1 0 1 0 0 1 1 1 0 E


F D B C S A E

F D B S C A E

D F A C B S E

D F B A C S E

F A S E D B C

Cell D

BSC1

BSC2

MSC

Answer(The 14th Bit)

1 1 1 1 1 9 8 7 6 5 4 3 2 1 C ll




-73dBm

Cell A

Cell B

Cell CCell E

Cell F

Cell S

Cell D

-90dBm

-80dBm

-83dBm

-75dBm

-70dBm

-85dBm


F D B C S A E

F D B S C A E

D F A C B S E

D F B A C S E

F A S D B C E

F S E D B C A

1

4

1

3

1

2

1

1

1

0

9 8 7 6 5 4 3 2 1 Cell

0 0 0 0 1 0 0 0 0 1 0 0 0 0 F

0 0 1 0 0 1 0 0 1 1 0 0 0 1 D

0 0 1 0 1 1 0 0 0 1 0 0 1 0 B

1 0 1 0 1 1 C

0 0 0 1 1 1 0 0 0 1 0 1 0 0 S

1 0 1 1 0 1 A

0 0 0 1 1 1 0 1 0 0 1 1 1 0 E

[Inter-layer HO Threshold](s&n)＝25

[Inter-layer HO Hysteresis](s&n)＝ 3dB

Serving cell’s threshold：-88dBm

Neighbor cell’s threshold：-82dBm

Given condition:

Then we can get:

Answer(TA HO)




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

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

Which cell is the target cell?

Target cell is cell E

Answer(Interference HO)

Cell ASuppose: Cell S’s quality is 7




Candidate cell list（high－

>low） S F E D B C A

Cell B

Cell C

Cell E

Cell F

Cell S

-85dBm

-80dBm

-90dBm

-83dBm

-75dBm

-73dBm

-70dBm

Suppose: Cell S s quality is 7

1) [Intracell HO Allowed](s) is Yes ，which is the target cell?

Answer: Intra cell HO, andtriggering sequence: differentfrequency band ->different TRX-

>different TS2) [Intracell HO Allowed](s) is No ，


Answer: Cell F

[Inter-layer HO Threshold](s/n)＝25

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

Neighbor cell threshold：-82dBm

Question




Pl th f ll i ti

Question




Please answers the following questions:

1. What’s the neighbour cell sequence basing on MS

measurement report?

2. What’s the neighbour cell sequence on BSC after 16-bit

ranking?

3. What cell is the target cell? and what’s the handover type?

Answer

1 What’s the neighbour cell sequence on MS (on MS measurement




1. What s the neighbour cell sequence on MS (on MS measurement

report)?

Cell Band Rx_Level(-dBm)

(Serving cell)A 900 -86

C 900 -66

F 900 -69

B 1800 -73

D 1800 -81

E 900 -72

H 900 -84

2 MBR

Answer2. What’s the neighbour cell sequence on BSC from 16-bit rule point of




view?

Cell14t

h12th 10th 4th 1st~3rd

Sweving

Cell A1 0 0 0 -86(110)

C 0 1 1 0 -66(000)

F 0 0 1 0 -69(001)

B 0 1 0 0 -73(011)

D 1 0 0 0 -81(100)

E 0 0 1 0 -72(010)

H 1 0 0 1 -84(101)

Cell14t

h12th 10th 4th 1st~3rd

F 0 0 1 0 -69(001)

E 0 0 1 0 -72(010)

B 0 1 0 0 -73(011)

C 0 1 1 0 -66(000)

D 1 0 0 0 -81(100)

Serving

Cell A1 0 0 0 -86(110)

H 1 0 0 1 -84(101)

Before 16 bits ranking After 16 bits ranking

3 What cell will be chosen by MS for handover and what’s the handover

Answer




3. What cell will be chosen by MS for handover and what s the handover

type? It’s clear that F cell will be chosen for target. And it will be PBGT

handover, because only PBGT conditions are met:

The layer and level of the object cell are the same as those of the service cell.

Satisfy Path loss (s) – Path loss (n) >PBGT HO Threshold or RxLev (serving) –

RxLev (candidate)>PBGT HO Thrsh.

In our case PBGT HO Thrsh=68=4 dB and cell layer serving and neigboor cells

are the same.



Thank youwww.huawei.com

omo131020 bsc6900 gsm v9r11r12r13 handover algorithm i issue1.11

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