Omf810002 gsm handover algorithm issue2 01 by Emerson Eduardo Rodrigues

GS M Ha ndove r Algorithm www.huawei.com

Fore word 

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



Handover algorithm in Huawei product is flexible and powerful.

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Obje ctive s 

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

Page4

Conte nts 1.

Introduction of Handover

HO Algorithm Process

Page5

Conte nts 1.

Introduction of Handover

HO Algorithm Process

Page6

P urpos e s 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

Page7

Cla s s ifica tion by Re a s on 1

Emergency HO

Enhanced Dual Band HO

Classification by 3 Reason 4

No DL MR Emergency HO Timing Advance (TA) HO Interference HO Rx_Level_Drop HO Bad Quality (BQ) HO

Load HO Normal HO

EDGE HO PBGT HO Layer HO MS Fast Moving HO Concentric Cell HO AMR HO

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Cla s s ifica tion by S ynchroniza tion

NSS Network

MSC

BSC

MSC

BSC

BTS BTS

CELL

Case 1

Case 2

Case 3

BTS

Case 4

BTS

Case 5

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

Page9

Cla s s ifica tion by Equipme nt a nd Cha nne l Intra – Cell HO

Inter – Cell HO

TCH → TCH

Intra – BSC HO

SDCCH → SDCCH

Intra – MSC HO Inter – MSC HO

SDCCH → TCH (Direct Retry)

Page10

Conte nts 1.

Introduction of Handover

HO Algorithm Process

Page11

Conte nts 2.

HO Algorithm 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

Page12

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Measure and Measurement Result Report

Measurement Report Preprocessing

Handover Judgment Handover Implementation MS Goes into New Dedicated Mode

Page13

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Measure and Measurement Result Report

Measurement Report Preprocessing

Handover Judgment

Handover Implementation MS Goes into New Dedicated Mode

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Me a s ure me nt Re port 

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.

The downlink MR

The downlink measurement report of the neighbor cell (BCCH)

The uplink MR

Serving cell Neighbor cell

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Me a s ure me nt Re port

Page16

P e riod of Me a s ure me nt Re port 

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

4 TCH Multiframes

480ms

12TCH

1SACCH

12TCH

1 Idle

Page17

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Measure and Measurement Result Report

Measurement Report Preprocessing

Handover Judgment Handover Implementation MS Goes into New Dedicated Mode

Page18

MR P re proce s s ing Interpolation

 

Re cove r the los t m e a s ure m e nt re port

Filtering

 

Sm o o th th e in s t a n t a n e o u s fa d in g p o in t

MR Preprocessing

Page19

MR Inte rpola tion Flow R sM u o tinu Con

…

No. n+4

…

No. n

Missing by some reasons

Page20

MR Filte ring

us M o u tin Con

ow R Fl MR

…

Filter----Average several consecutive MRs

Page21

Da ta Configura tion of MR P re proce s s ing

Page22

Da ta Configura tion of MR P re proce s s ing

Page23

Da ta Configura tion of MR P re proce s s ing

Page24

Da ta Configura tion of MR P re proce s s ing

Page25

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Penalty Processing Ranking Processing

1 Measure and Measurement Result Report

OM Forced HO Direct Retry

MR. Preprocessing

Handover Judgment

4 Handover Implementation

MS Goes into New Dedicated Mode

Emergency HO

Enhanced Dual Band HO Load HO Normal HO Edge HO

No DL MR HO

MS Fast Moving HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

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P e na lty P roce s s ing Punish on the target cell

AMR HO Fails

Intra-cell HO

Emergency (TA&BQ)HO

HO Fails

Punish on the original cell

Penalty

MS Fast Moving HO

Concentric Cell HO

Punish on other high priority layer cells

Page27

P e na lty for Ha ndove r Fa ilure 

Punish the target cell when a HO fails.



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

Cell A BTS

HO Fail BTS

BSC

Cell B

Page28

Da ta Configura tion of P e na lty for Ha ndove r Fa ilure

Page29

Da ta Configura tion of P e na lty for Ha ndove r Fa ilure

Page30

P e na lty for Eme rge ncy Ha ndove r 

Punish the original cell when an emergency HO ( due to BQ and TA) occurs.

Cell A

BTS

BQ&TA HO

BSC Cell B

Page31

Da ta Configura tion of P e na lty for Eme rge ncy Ha ndove r

Page32

Da ta Configura tion of P e na lty for Eme rge ncy Ha ndove r

Page33

P e na lty for MS Fa s t-moving Ha ndove r 

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



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

Back? No way!

Umbrella

Page34

Da ta Configura tion of P e na lty for MS Fa s t-moving Ha ndove r

Page35

P e na lty for Conce ntric Ce ll ď Ź

A new concentric cell HO is prohibited within a penalty time after a concentric cell HO failure. Do not attempt again after N failed HO(U->O)!

Overlaid Underlaid

Do not attempt again during penalty time after one failed HO(O->U)!

Page36

Da ta Configura tion of P e na lty for Conce ntric Ce ll

Page37

P e na lty for Enha nce d Conce ntric Ce ll 

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

Overlaid Underlaid

Do not attempt back too fast!

Page38

Da ta Configura tion of P e na lty for Enha nce d Conce ntric Ce ll

Page39

P e na lty for Intra -ce ll HO ď Ź

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

4th. 3rd.

2nd. 1st.

Penalty time 0

Max. consecutive HO times: 3 Forbidden time after Max. times: 20s Interval for consecutive HO Jud: 6s

Page40

T (s)

Da ta Configura tion of P e na lty for Intra -ce ll HO

Page41

Da ta Configura tion of P e na lty for AMR FRHR Ha ndove r Fa ilure

Page42

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Penalty Processing Ranking Processing

1 Measure and Measurement Result Report

OM Forced HO Direct Retry

MR. Preprocessing

Handover Judgment

4 Handover Implementation

MS Goes into New Dedicated Mode

Emergency HO

Enhanced Dual Band HO Load HO Normal HO Edge HO

No DL MR HO

MS Fast Moving HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

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Ra nking P roce s s ing Basic ranking



M rule



K rule

Network feature adjustment

16 bits ranking



The ranking result: target cell selection of handover

Page44

M Rule Begin

Yes

Finish to all neighbor cells?

End

No No

An BSC external neighboring cell& the current channel is SDCCH ?

Yes

Direct retry?

[Inter-BSC SDCCH HO Allowed] (S) is Yes?

Yes

Delete the cell from the cell list?

Yes

? the cell overload

No RX_LEV_DL(n) < [Min DL Power on HO Candidate Cell](n)+ [Min Access Level Offset](s->n)?

Yes

Delete this cell from the cell list

No RX_LEV_UL(n) < [Min UP Power on HO Candidate Cell](n)+ [Min Access Level Offset](s->n)?

Yes

For service cell: Min Access Level Offset=0

M rule will remove the neighbor cells from the candidate cell list according to the flow.

Page45

Da ta Configura tion of M Rule

Page46

Da ta Configura tion of M Rule

Page47

Ne twork Fe a ture Adjus tme nt 

After network feature adjustment, all the candidate cells have their own 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.

hest The Hig Weight

9 11 10 2 1 14 13 16 15

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w es t The Lo t Weigh

Ne twork Fe a ture Adjus tme nt 

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. 

Th e v a lu e s c o m e fr o m m a x . 6 c a n d id a t e c e lls a n d 1 s e r v in g c e ll a c c o r d in g t o t h e le v e l ra n g e s fro m 0 0 0 ~ 1 1 0 . Th e v a lu e fo r t h e c e ll w it h t h e s t ro n g e s t s ig n a l le v e l is 0 0 0 , fo r t h e c e ll w it h s e c o n d s t ro n g e s t s ig n a l le v e l is 0 0 1 a nd so on.



Actually that is the core of K rule. 16

Page49

Ne twork Fe a ture Adjus tme nt 

The 4th bit: [Inter-cell HO hysteresis] bit.

Yes

serving cell?

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

Always set to 0

Yes

Set to 0

No Set to1

Page50

Da ta Configura tion of Inte r-ce ll HO Hys te re s is

Page51

Ne twork Fe a ture Adjus tme nt 

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.

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Hie ra rchica l Ce ll S tructure Layer 4 （ low ）

GSM 900

Umbrella Cell

GSM 900

GSM900 Cell

GSM1800

GSM1800 Cell

Micro Cell

GSM900

GSM1800

Page53

Layer 3

Layer 2

Layer 1 （ high ）

Da ta Configura tion of Ce ll Hie ra rchica l Ne twork S tructure

Page54

Ne twork Fe a ture Adjus tme nt 

The 11th bit: The bit value is decided by cell-load-sharing criterion. 

This bit is affected by 14th bit. Yes

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

11th bit is turned off

No Yes

serving cell?

Cell load >= [Load HO Threshold](s)?

Yes set to 0

Yes

set to 1

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

set to 1

set to 0

Page55

Da ta Configura tion of Ce ll-loa d-s ha ring

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Da ta Configura tion of Ce ll-loa d-s ha ring

Page57

Ne twork Fe a ture Adjus tme nt 

12th bit and 13th bit: Whether share the same BSC or MSC. Yes

Yes

Both 12th and 13th set to 0 Yes

Co-BSC?

Co-MSC?

12th set to 1 13th set to 0

12th set to 0 13th set to 0

Turn off 12th &13th bit

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

Yes

serving cell?

12th set to 1 13th set to 1

Page58

Da ta Configura tion of Co-BS C&MS C

Page59

Ne twork Fe a ture Adjus tme nt The 14th bit: [Inter-layer HO Threshold/Hysteresis] adjustment bit.



Yes

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

Yes

serving cell?

RX_LEV_DL >= [Inter-layer HO Threshold](n) + [Inter-layer HO Hysteresis](s->n)? Yes No

No set to 0



set to 0

Bit 14th set to 1, and bit 5th ~13th are turned off

The 15th/16th bits are reserved 16

Page60

Da ta Configura tion of La ye r HO Thre s hold Adjus tme nt

Page61

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Penalty Processing Ranking Processing

1 Measure and Measurement Result Report

OM Forced HO Direct Retry

MR. Preprocessing

Handover Judgment

4 Handover Implementation

MS Goes into New Dedicated Mode

Emergency HO

Enhanced Dual Band HO Load HO Normal HO Edge HO

No DL MR HO

MS Fast Moving HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

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No DL MR HO ď Ź

When the quality of Um interface become worse and worse, it is 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.

Bad uplink quality

Serving Cell

Neighboring Cell

Page63

P os ition of No DL MR HO MS Goes into Dedicated Mode

Measure and Measurement Result Report MR. Preprocessing

Penalty Processing Ranking Processing OM Forced HO Direct Retry Emergency HO

Handover Judgment

4 Handover Implementation MS Goes into New Dedicated Mode

Load HO Normal HO Edge HO MS Fast Moving HO

No DL MR HO 3

Enhanced Dual Band HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

Page64

No DL MR HO UL_Qua. (after filtering) >=[No Dl Mr.Ul Qual HO Limit](s)?

No Begin

Yes No

[No Dl Mr. HO Allowed](s) Yes ?

Yes

Yes No

No Dl Mr. in current Mr.? Yes

End

Yes [Intracell HO Allowed](s)?

Within Penalty Time No Trigger No DL Mr. HO signal quality filter length: For TCH:[Filter Length for TCH Qual] For SDCCH:[Filter Length for SDCCH Qual]

Select the candidate cell with the highest priority, exluding serving cell

Yes Yes

Yes No

serving cell?

Report 1 DL MR at least? Yes <=[Cons.No Dl Mr. Ho Allowed Limit] (s)?

Only one cadidate cell?

Page65

Da ta Configura tion of No DL MR HO

Page66

TA(Time Adva nce ) HO Handover Triggering

TA(s)

TA(n) Handover Triggering Zone

[TA Threshold](n)

[TA Threshold](s) or

Time

Serving Cell

Neighboring Cell

Page67

TA(Time Adva nce ) HO Begin

End

[TA HO Allowed] Yes ? Yes

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

Select the cell with the highest priority in the cadidate cell list

serving cell? No

Yes No

Any neighbour cell exist? Yes

Yes

[TA Threshold] (n,in the same BTS) <= [TA Threshold](s)

No No

Suitable cell exist? Yes Trigger TA handover

Page68

Yes

Da ta Configura tion of TA HO

Page69

Inte rfe re nce Ha ndove r RX_Lev Handover Triggering Zone Lev_Thr

Qual_Thr

Rx_Qual

Interference Origin

Serving Cell

Neighboring Cell

Page70

Inte rfe re nce HO Begin

Select the cell with the highest priority in the cadidate cell list

[Interference HO Allowed] Yes ? Yes

End

serving cell?

UL or DL receiving Quality(s)>=A? Yes

Yes

Any neighbour cell exist? Yes

None AMR FR: A = RXQUALn, 1<=n<=12 AMR FR: A = RXQUAL1, n=1; A = RXQUALn + RXLEVoff,

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

Rx_Level(n)>= [Inter-layer HO Threshold](n) + No [Inter-layer HO Hysteresis](s->n)?

Yes No

2<=n<=12

Yes Any suitable cell exist? Yes Trigger interference handover

Page71

Da ta Configura tion of Inte rfe re nce HO Default Value Receiving Level(-110dBm) Parameter

Receiving Quality

RXQUAL1

<=30

RXQUAL2

=31

RXQUAL3

32~35

RXQUAL4

36~38

RXQUAL5

39~41

RXQUAL6

42~45

RXQUAL7

46~48

RXQUAL8

49~52

RXQUAL9

53~55

RXQUAL10

56~58

RXQUAL11

59~62

RXQUAL12

>=63

Page72

Da ta Configura tion of Inte rfe re nce HO

Page73

Rx_Le ve l_Drop HO

Page74

Rx_Le ve l_Drop HO Begin

[Rx_Level_Drop HO Allowed] Yes ?

Select the cell with the highest priority in the cadidate cell list

Yes End

Satisfy the Formula& The latest RX_LEV_UL(s) < [Edge HO UL RX_LEV Threshold] (s)?

Yes No

Yes

serving cell?

End

Any neighbour cell exist? Yes

Formula:

Is priority higher than serving cell? Yes Trigger Rx_Level_Drop handover

( A1 − 10) X 1 + ( A2 − 10) X 2 + ( A3 − 10) X 3 + ( A4 − 10) X 4 + ( A5 − 10) X 5 + ( A6 − 10) X 6 + ( A7 − 10) X 7 + ( A8 − 10) X 8 < − B

Page75

Da ta Configura tion of Rx_Le ve l_Drop HO

Page76

BQ(Ba d Qua lity) HO Begin

Is [BQ HO Allowed] Yes ?

Select the cell with the highest priority in the cadidate cell list

Yes End

UL_Rx_Q(s)>=[UL Qual. Threshold](s) or DL_ Rx_ Q(s) >=[DL Qual. Threshold](s)?

Yes No

Any neighbour cell exist? Yes

Yes

serving cell?

No [Intracell HO Allowed](s) yes & cell not punished?

No No

RX_LEV_DL (n) > RX_LEV_DL (s) + Inter-cell HO hysteresis(s->n) -BQ HO Margin(s->n) ?

Yes

Yes No

Suitable cell exist? Yes Trigger BQ handover

Page77

Da ta Configura tion of BQ HO

Page78

Da ta Configura tion of BQ HO

Page79

Da ta Configura tion of BQ HO

Page80

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Penalty Processing Ranking Processing

1 Measure and Measurement Result Report

OM Forced HO Direct Retry

MR. Preprocessing

Handover Judgment

4 Handover Implementation

MS Goes into New Dedicated Mode

Emergency HO

Enhanced Dual Band HO Load HO Normal HO Edge HO

No DL MR HO

MS Fast Moving HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

Page81

Enha nce d Dua l Ba nd 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.

Page82

Cha nne l As s ignme nt of Enha nce d Dua l Ba nd 

TCH assignment (SDCCH channel in UL) Begin from UL No

[Assignment Optimization of UL Subcell Allowed or not] (u) ?

Yes Cell load of UL > [UL Subcell General Overload Threshold(%)](u)?

No Assign TCH in UL or direct retry identification or queuing

Yes No

Yes A Any idle TCH Available in OL?

Yes

Assign TCH in OL

RX_LEV_OL>= [Incoming OL Subcell HO level Threshold(dB)](o) and RX_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.

Page83

Da ta Configura tion of Cha nne l As s ignme nt

Page84

Da ta Configura tion of Cha nne l As s ignme nt

Page85

Cha nne l As s ignme nt of Enha nce d Dua l Ba nd 

TCH assignment (SDCCH channel in OL) Begin from OL

[Assignment Optimization of OL Subcell Allowed or not ](o) No ?

Yes Assign TCH in UL

Assign TCH in OL or direct retry identification or queuing

Yes

Cell load of UL< [UL Subcell Lower Load Threshold](u)? Yes

Any idle TCH Available in OL?

Assign TCH in OL

Any idle TCH Available in UL? Yes Assign TCH in UL

Page86

Da ta Configura tion of Cha nne l As s ignme nt

Page87

Enha nce d Dua l Ba nd HO 

Classification of TCH HO in enhanced dual band HO

UL to OL for high load in UL

OL to UL for low load in UL

OL to UL for moving

Page88

Enha nce d Dua l Ba nd HO(UO ) 

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

Page89

Enha nce d Dua l Ba nd HO(UO ) 

Triggering condition for TCH Load HO from UL to OL for high load in UL [Load HO From UL Subcell to OL Subcell Allowed](u) Yes ?

Begin

End

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

Yes

Refresh cell load per second

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

B-C No

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

Yes No

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

No B

Adjust HO zone basing on HO step and HO period

Yes

Any MS in HO zone?

Yes Trigger UL to OL A:

RX_LEV_OL >= [Incoming OL Subcell HO level Threshold(dB)] (o)and RX_LEV_UL – RX_LEV (n) > [Distance Between Boundaries of UL and OL Subcells(dB)]

Page90

Da ta Configura tion of Enha nce d Dua l Ba nd HO(UO )

Page91

Da ta Configura tion of Enha nce d Dua l Ba nd HO(UO )

Page92

Enha nce d Dua l Ba nd HO(OU ) 

Triggering condition for TCH HO from OL to UL for moving [Inner Cell Edge HO Enable] (o)Yes ?

Begin

Yes

RX_LEV_OL < RX_LEV_UL

A Yes Satisfy P/N?

No End

Yes Select Neighbor cell with the highest priority Trigger OL to UL A:

RX_LEV_OL <[Outgoing OL Subcell HO level Threshold(dB)](o) or 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)]

Page93

Da ta Configura tion of Enha nce d Dua l Ba nd HO(OU )

Page94

Enha nce d Dua l Ba nd HO(OU ) 

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

Page95

Enha nce d Dua l Ba nd HO(OU ) 

Triggering condition for TCH Load HO from OL to UL for low load in UL Begin [Load HO of OL Subcell to UL Subcell Enable](o) Yes ?

End

Yes Refresh cell load per second No

Cell load of UL <[UL Subcell Lower Load Threshold(%)] (u)?

Yes No

Satisfy P/N? Yes

Adjust HO zone basing on HO step and HO period Any MS in HO zone? Yes The object cell must be the underlaid subcell and satisfy condition A

Trigger OL to 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) Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page96

Da ta Configura tion of Enha nce d Dua l Ba nd HO(OU )

Page97

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Penalty Processing Ranking Processing

1 Measure and Measurement Result Report

OM Forced HO Direct Retry

MR. Preprocessing

Handover Judgment

4 Handover Implementation

MS Goes into New Dedicated Mode

Emergency HO

Enhanced Dual Band HO Load HO Normal HO Edge HO

No DL MR HO

MS Fast Moving HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

Page98

Loa d HO Handover triggering zone Load of Serving Cell

Load of Neighboring Cell

[Load HO Threshold] [Load Req. on Candidate Cell]

Time

Normal Cell

Congested Cell

Congested Cell Normal Cell

Normal Cell

Page99

Loa d HO ď Ź

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.

Page100

Loa d HO Normal Cell

Congested Cell

Normal Cell Normal Cell

Page101

Loa d HO Begin No

End

Select the cell with the highest priority in the cadidate cell list

[Load HO Allowed] (s) Yes ? Yes

Yes

Yes No

No Star timer T

Load of service cell >= [Load HO Threshold] (s)?

Yes Load HO timer T begin? Yes Load HO timer T overflow?

Yes

BSC internal cell?

C &D

Yes End Yes

Yes Suitable cell exist?

Yes

Trigger load handover

B: [Edge HO_DL_RX_LEV Threshod](s)<DL_RX_Lev(s) < [Edge HO_DL_RX_LEV Threshod](s)+A

A= [Load HO Bandwidth] (s)

A= T ( + 1) × Step Period

Yes

serving cell?

Current system flux<= [System Flux Threshold for Load HO](s)?

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)

Step ≤ A ≤ [Load HO Bandwidth] ⇒ 0 ≤ T ≤ (

[Load HO Bandwidth] − 1) × Period Step

Page102

Da ta Configura tion of Loa d HO

Page103

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Penalty Processing Ranking Processing

1 Measure and Measurement Result Report

OM Forced HO Direct Retry

MR. Preprocessing

Handover Judgment

4 Handover Implementation

MS Goes into New Dedicated Mode

Emergency HO

Enhanced Dual Band HO Load HO Normal HO Edge HO

No DL MR HO

MS Fast Moving HO

TA HO

Layer HO

Interference HO

PBGT HO

Rx_Level_Drop HO

Concentric Cell HO

Bad Quality HO

AMR HO

Page104

Edge Ha ndove r Handover Triggering

RX_Lev

RX_LEV Thr

Time

P/N P: Watch Time N: Valid Time

Serving Cell

Neighboring Cell

Page105

Edge HO Begin No

[Fringe HO Allowed](s) Yes ?

Select cell(n) whose 16 bit priority is higher than serving cell and whose level satifys P/N rule(n) basing on A

Yes UL_Rx_Lev(s) < [Edge HO UL RX_LEV Threshod](s)?

No Satisfy P/N rule(s)?

Yes Refresh its timer

Yes

Yes Trigger Edge handover

No DL_Rx_Lev(s) < [Edge HO DL RX_LEV Threshod](s)?

End

Any neighbor cell?

Yes Refresh its timer

No Satisfy P/N rule(s)?

Yes A: DL_Rx_Lev(n)> DL_Rx_Lev(s)+[Inter-cell HO Hysteresis](s->n)

Page106

Da ta Configura tion of Edge HO

[Edge HO UL/DL RX-LEV Threshold]<[UL/DL RX_LEV Lower Threshold] in HWII/III power control tabel

Should be lower than the[Outgoing OL Subcell HO Level Threshold(dB)] in enhance dual band data table

Page107

Da ta Configura tion of Edge HO

Page108

Da ta Configura tion of Edge HO

Page109

MS Fa s t-Moving Ha ndove r Handover Triggering

Time

Time Threshold

P/N

Cells Number

P: Watch Cells N: Valid Cells

Umbrella Cell Micro Cell

Page110

MS Fa s t-Moving Ha ndove r Begin No

[MS Fast Moving HO Allowed](s) Yes ? Yes

Yes

the serving cell on layer 4? No

End

Refresh timer(s) No

Satisfy P / N rule?

Any cell satisfy the condition above?

Yes

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)

Yes

Trigger MS fastmoving handover

Page111

Da ta Configura tion of MS Fa s t-moving Ha ndove r

Page112

La ye r HO

GSM900 Cell （ Lay 3 ）

Serving Cell

GSM1800 Cell （ Lay 2 ）

Neighboring Cell

Page113

La ye r HO Begin [Level HO Allowed](s) Yes ? Yes Any neighbor cell exit?

End

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

Identify the next cell

Yes A & ( layer(n)< layer(s) or level(n)<level(s) )? Yes Satisfy P/N rule(n)?

Yes Trigger layer handover

A: RX_LEV(n)>= [nter-layer HO threshold](n) + [Inter-layer HO hysterisis](s->n)

Page114

Da ta Configura tion of La ye r HO

Page115

Da ta Configura tion of La ye r HO

Page116

Da ta Configura tion of La ye r HO

Page117

P BGT HO

Handover Triggering

Path Loss (dB)

PBGT HO 5 Threshold

P/N

Time P: Watch Time N: Valid Time

126-119=7dB>5dB

126dB

119dB

Serving Cell

Neighboring Cell

Page118

P BGT HO [PBGT HO Allowed] (s)Yes ?

Begin

Yes current channel signaling channel?

Yes

No Search next neighborcell No

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

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

End

No Satisfy P / N rule?

Yes Trigger PBGT HO

NOTES: whichever the greater of the [inter-cell HO hysteresis] and [PBGT HO threshold], that value will be used in the PBGT HO.

Page119

Da ta Configura tion of P BGT HO

Page120

Da ta Configura tion of P BGT HO

Page121

Conce ntric Ce ll 



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

Page122

Cla s s ifica tion a nd HO J udgme nt of Conce ntric Ce ll … Normal concentric cell

… Enhance concentric cell

Receiving level



Time advance



Quality



Time advance Quality ATCB



Cell load of underlaid



Page123

Da ta Configura tion of Conce ntric Ce ll

Page124

Norma l Conce ntric Ce ll HO ď Ź

Division of underlaid and overlaid is decided by MS downlink receive level ,TA value and quality.

underlaid Receiving Level Threshold Receiving Level Hysteresis Receiving Qaulityl Threshold

overlaid

TA Threshold TA Hysteresis

Page125

Norma l Conce ntric Ce ll HO

U to O

O to U

Page126

Norma l Conce ntric Ce ll HO(OU ) Flow for TCH HO from overlaid to underlaid



No [OL to UL HO Allowed] Yes ?

Begin

Yes

within Penalty Time

Yes

End

No No

[RX_LEV for UO HO Allowed] Yes? Yes

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

[TA for UO HO Allowed] Yes?

[RX_QUAL for UO HO Allowed] Yes?

Yes Rx_Dl_Quality>= No [RX_QUAL Treshold]?

No Current TA>=[TA Threshold]+ [TA Hysteresis]?

Yes

Yes P/N rule ? Yes

Yes

End

Trigger OL to UL

Yes

Page127

Norma l Conce ntric Ce ll HO(UO ) 

Criterion for TCH HO from underlaid to overlaid Begin [UL to OL HO Allowed] Yes ?

No End

Yes

With Penalty Time ?

Yes

No [RX_LEV for UO HO Allowed] Yes?

Yes

No [RX_QUAL for UO HO Allowed] Yes? No [TA for UO HO Allowed] Yes?

Yes

End Rx_Dl_Level >= [RX_LEV Threshold] + [RX_LEV Hysteresis] Yes Rx_Dl_Qual<= [RX_QUAL Treshold]?

Yes Current TA<=[TA Threshold]- No [TA Hysteresis]?

No P/N rule ? Yes Trigger UL to OL

Page128

Da ta Configura tion of Norma l Conce ntric Ce ll HO

Page129

Da ta Configura tion of Norma l Conce ntric Ce ll HO

Page130

Da ta Configura tion of Norma l Conce ntric Ce ll HO

Page131

Enha nce Conce ntric Ce ll HO ď Ź

Division of underlaid and overlaid is decided by MS downlink receive level, quality, TA value and cell load of underlaid.

underlaid U to O HO Receiving Level Threshold O to U HO Receiving Level Hysteresis Receiving Qaulityl Threshold

overlaid

TA Threshold TA Hysteresis

Page132

Enha nce Conce ntric Ce ll HO ď Ź

Classification of TCH HO in enhance concentric cell HO

U to O for high load in U

O to U for moving

O to U for low load in U

Page133

Enha nce Conce ntric Ce ll HO(UO ) 

Flow for TCH HO from underlaid to overlaid for high load in UL Begin [UL to OL HO Allowed] Yes ?

No End

Yes

Within Penalty Time ?

Yes

End

No [RX_LEV for UO HO Allowed] Yes? No [ATCBHoSwitch] Open?

Yes

Rx_Dl_Level>[UtoO HO No Received Level Threshold] Yes

Yes

A Yes

No [RX_QUAL for UO HO Allowed] Yes? No [TA for UO HO Allowed] Yes? No

Rx_Dl_Qual< [RX_QUAL Treshold]?

Yes

Yes Yes P/N rule ?

Current TA<[TA Threshold]- No [TA Hysteresis]? Yes

Yes Go to the user selection flow in the next slide

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 layer with underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBm Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page134

Enha nce Conce ntric Ce ll HO(UO ) (Con.) 

User selection flow from UL to OL for high load in UL [UtoO Traffice HO Allowed] Yes ?

Begin

Yes Refresh cell load per second Yes No

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

Cell load of UL>=[En Iuo Out Cell Serious OverLoad Thred]?

(B-1)/second

Yes

Adjust HO zone basing on HO step and HO period

End No 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 Trigger UL to OL

Page135

Enha nce Conce ntric Ce ll HO(OU ) 

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

Begin

[[OL to UL HO Allowed] Yes ?

End

Yes Refresh cell load per second No

Adjust HO zone basing on HO step and HO period

Cell load of UL<[En Iuo Out Cell Low Load Thred]?

Yes

Any MS in HO zone? Yes Trigger UL to OL

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

Page136

Enha nce Conce ntric Ce ll HO(OU ) 

Flow for TCH HO from overlaid to underlaid for moving No [OL to UL HO Allowed] Yes ?

Begin

Yes

With Penalty Time ?

Yes

End

[RX_LEV for UO HO Allowed] Yes? Rx_Dl_Level<[OtoU HO Received Level Threshold] Yes

[ATCBHoSwitch] No No Open? No

[TA for UO HO Allowed] Yes?

[RX_QUAL for UO HO Allowed] Yes? Yes Rx_Dl_Qual> [RX_QUAL Treshold]?

Yes

No Current TA>[TA Threshold]+ [TA Hysteresis]?

Yes

P/N No rule End ? Yes Select the underlaid subcell or the neighbour cell with the highst priority in 16 bits list

Yes

Trigger OL to 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)] Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page137

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page138

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page139

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page140

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page141

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page142

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page143

Da ta Configura tion of Enha nce Conce ntric Ce ll HO

Page144

Cha nne l As s ignme nt s tra te gie s of Conce ntric Ce ll Channel Assignment Strategies of Concentric Cell

Immediate Assignment

Assignment

Intra-BSC Inter-cell Handover

Incoming Cell Handover

Page145

Imme dia te As s ignme nt 

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 bigger

TA smaller

Page146

Da ta Configura tion of Imme dia te As s ignme nt

Page147

As s ignme nt 

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

Page148

Da ta Configura tion of As s ignme nt

Page149

Intra -BS C Inte r-Ce ll Ha ndove r 

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.

According to the Rx-level

Overlaid overlaid

Underlaid

Page151

Da ta Configura tion of Intra -BS C Inte rCe ll Ha ndove r

Page152

Inte r-BS C Ha ndove r ď Ź

For the inter-BSC Handover, if the target cell is concentric cell , the channel of underlay cell should be assigned first. BSC2

BSC1

Overlaid overlaid

Assign underlaid first

Underlaid

Page153

Da ta Configura tion of Inte r-BS C Inte rCe ll Ha ndove r

Page154

AMR Ha ndove r Flow Begin Are [Intracell HO Allowed] & [Intracell F-H HO Allowed ］ Yes ?

Yes No

End

Is current channel TCH & version3? Yes During [Penalty Time after AMR TCHF-H HO Fail(s)]?

Yes

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

No Yes

current channel is FR

RQI/2 >[F2H HO th] & A

RQI/2 <[H2F HO th]

End

Yes

Yes No

Satisfy P/N rule?

Yes Trigger internal cell AMR handover

Page155

Da ta Configura tion of AMR HO

Page156

Da ta Configura tion of AMR HO

Page157

Ge ne ra l HO P roce s s MS Goes into Dedicated Mode

Measure and Measurement Result Report

Measurement Report Preprocessing

Handover Judgment

Handover Implementation MS Goes into New Dedicated Mode

Page158

Ha ndove r Imple me nta tion Begin

BTS(s) keeps current power output

[Power boost befor HO enabled or not ］ (s)Yes ?

For BTS

Yes

BTS(s) uses the max. power output

BSC send “HO Command” to MS

No power control during handover in order to make sure the handover is successful

HO execute

Page159

Da ta Configura tion of Ha ndove r Imple me nta tion(BTS )

Page160

Ha ndove r Imple me nta tion Begin

MS uses the highest power to access

[MS Power Prediction after HO ］ (s) Yes ?

For MS BSC send “HO Command” to MS

No power control during handover in order to make sure the handover is successful

Yes

BSC predict power

MS will use this predict power in new cell after finishing this handover

HO execute

Page161

Da ta Configura tion of Ha ndove r Imple me nta tion(MS )

Page162

Da ta Configura tion of Ha ndove r Imple me nta tion(MS )

Page163

S umma ry 

In this course, we have learned: 

Classification of HO



HO general procedure



HO judgment algorithm



HO implementation process



HO data configuration

Page164

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