gsm p&o training material for special subject-handover algorithms - zte

8/17/2019 GSM P&O Training Material for Special Subject-Handover Algorithms - ZTE

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GSM Handover Algorithms

----Special Subject Training V1.4

Suitable or sta !ith junior "#$ s%ill certiicates &lo!er than certiicate '''(

'ssued b) GSM *et!or% "lanning # $ptimi+ation ,ept.


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Internal Use Only▲

Version introduction

Version Date Writer Assessor Amendment record

V1.0 2007-07-25

Chen Chun Zheng Hao None

V1.4 2009-03-12

Fei Aiping Chang Haijie Explanaion o! "# i$ a%%e%.


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Training goals

Get to know theories and classification

of GSM handover;

Get to know the various kinds of ZTEhandover algoriths!


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ontents

$vervie! o handover

lo! o handovers

/asic handover algorithms

Advanced handover algorithms

'nter-s)stem handovers


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Aims o handovers

BTS

Servingcell

Neighbour cell AFreq. A

Neighbour cellBFreq. B

Neighbour cell CFreq. C

To ensure normal phone calls

To improve call quality

GSM handover belongs to system hard handover.


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Aims o handovers

Retrieval handover—to

retrieve the on-going calls;

Marginal handover—to

improve the on-going call;

Intra-cell handover—to

reduce interference in the

cell;

Forced handover—to balance traffic dispersion

in different cells;

Directed retry—to improvethe call establishment rate.


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Handover eatures

Various algorithms

•

Various algorithms can unction simultaneously;•Controlled by s!itches;•System ma"es handover decision automatically.

Ordering oftarget cells

•Static #riority;•$esource available%&';

•Budget #o!er value.

Automatic trafficbalance

•(irected retry;•)raic load handover started by MSC;•*riority ad+ustment by traic load;

•Force directed,shit handover; &&&

Fast-fading handoveralgorithm

Unique penaltymechanism


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Application scenes or handovers ' ' scenes (

Algorithms

Scenes

U"#$"

interferencehandover

U"#$"

%ualityhandover

U"#$"

levelhandover

"ong

MS&'Sdistancehandover

U"

fast&fadinghandover

Macro

&icrohandover

('GT

handover

Traffic

loadhandoverstarted)y MS*

*o&'**+

handover

,orced

traffic&shifthandover

(athloss-T.&)asedconcentrichandover

*I&)asedconcentrichandover

urban - - - - - - -

,enseurban

- - - - - - - - - -

suburb - - - -

)he table is or reerence only


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Application scenes or handovers '' ' net!or%t)pes (Algorithms

Scenes

U"#$"interfer

encehandover

U"#$"%uality

handover

U"#$"level

handover

"ongMS&'S

distancehandover

U"fast&

fadinghandover

Macr o&

icr ohandover

('GThandov

er

Trafficload

handoverstarted)yMS*

*o&'**+handover

,orcedtraffic&

shifthandover

(athloss-T.&)asedconcentrichandover

*I&)asedconcentrichandover

,ual-bandnet!or%

- - - - - - -

,ouble-la)ernet!or%

- - - - - - - -

$-/H - - - - - -

0ong-distancecoverage

- - - - -

)he table is or reerence only


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ontents

$vervie! o handover

lo! o handover



'nter-s)stem handover


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$verall handover lo!

* r o c e s s

o

M $

(ecisiono

handover

start

Selectiono target

cells

/rderingo target

cells

Start ohandover

* e n a l t y

s t r a t e g y o r

h a n d o v e r

a i l u r e

/verall handover lo!/verall handover lo!


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hat is M23

0. (1 ()2 #erormance3. 41 receive level5quality6. BS *o!er7. MS #o!er level8. )A9. (1 dynamic #o!er control

41 M$

(1 M$ 0. 41 ()2 #erormance3. (1 receive level5quality6. Ad+acent cell level7. 41 dynamic #o!er control


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M2 c)cle

M/ is sent to 'TS in S.**+ U" direction; 0hen MS is in S$**+1 M/ cycle is 234s#tie;

0hen MS is in T*+1 M/ cycle is 254s#tie!

03)C:03)C: 03)C:03)C:0SACC:0SACC: 00 )*)*

7


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"rocess o M2

eatures

Number o M$shall reach the

average si=e o!indo!;

)he ma> numbero missing M$ is

?eroAllo!ed;

@hen #o!ercontrol is on

#o!ercom#ensationshall be made to

handover decisionthreshold.

Consider ()2!eight;

Measurement re#ort is the original data base or handover decision. ?2G0< #rocessado#ts roll average method !ith various !eights !hich can ensure smooth handover.


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The ma number o missing M2 - 5eroAllo!ed

Su66ose Zero.llowed78M216"21

Average7M21M286"28

Average7M28M296"29

M246"24

M2:6"2:

M2;6"2;

M2


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Handover preprocess at /TS

Su66ose +O(re6rocess is o6en and the value is 9!

M$0

M$3

M$6

M$7

BSC

"reprocess 2esult1

"reprocess 2esult8

:/*re#rocess


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"rocess o M2 at /S

Su66ose window value721 :72M216"21

Average7M21M286"28

Average7M28M296"29

Average7M29

M246"24

Average7M24

*6" decision

M2:6"2:

M2;6"2;

M2


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Selection o target cells

Handover

t)pes

'ntra-cell

handover

Macrocell normal T2@

Macrocell special T2@

$ther T2@ in microcell

'nter-cell

handover

1 / Av20ev*ell&n( 2@0BV7M'*&n( >MA@&?C&MS7T@"27MA@&n(- "&n(((

8 / "/GT&n ( H$7MA2G'*&n(

9 / Av20ev*ell&n( av20ev,0 >H$7MA2G'*70BVB0&n(

4 / Av20ev*ell&n( av20ev,0 >

H$7MA2G'*7DEA0&n(

condition 0 must be satisied


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Settings o cell la)er # priorit)

,unctions of cell layer structure More reasona)le control of traffic dis6ersion;

*ontrol of traffic congestion;

'acku6 of network ca6acity redundancy!

Serial :andover causes :andover ty#es *riority Ater Tmicro

/eore Tmicro


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Internal Use Only▲Serial :andover causes :andover ty#es *riority Ater Tmicro

overtimes/eore Tmicroovertimes

8 !-"# Intra&cell Invalid Invalid

9 $% interference Intra&cell Invalid Invalid

< D% interference Intra&cell Invalid Invalid

2 $% &uality Inter&cell 'ame layer- upper layer-lo(er layer

$pper layer ) same layer-lo(er layer

= D% &uality Inter&cell 'ame layer- upper layer-lo(er layer


> $% level Inter&cell 'ame layer- upper layer-lo(er layer


3 D% level Inter&cell 'ame layer- upper layer-lo(er layer $pper layer ) same layer-lo(er layer

5 %ong distance Inter&cell 'ame layer- upper layer-lo(er layer


? $% fast fading Inter&cell First search for related cells

$pper layer ) same layer

lo(er layer

Invalid

84 *"+, Inter&cell .ccording to

()gt+o"ayer

Sae layer& u66er layer

lower layer

:o cells on sae layerand lower layerselected

88 Macro-micro timehyteresis

Inter&cell +andover to lower layer :o handover

89 ,raffic Inter&cell .ccording toTraffic+o"ayr*tl Traffic+o,re *tl

Invalid

Algorithmsare related totheir layers


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"arameter-*cell0a)er

@:cell"ayerA is a atheatical array! Each eleent

deterines the layer relation )etween the serving cell and its

adBacent cells!

The nu)er of cells in an array rests on :cell:u!

*cell*um 1alue

"eaning

0 N un%e!ine%

1 A"E he $eing ell an% i$ a%jaen ell$ ae onhe $a6e lae

2 8E# a%jaen ell$ ae on he $eing ell:$ uplae

3 ;lae


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0a)er parameter-Tmicro

Ticro is started when

the MS accesses into

new channel;

The layer selection

6riority of target cells

will )e affected1 if

handover is started

within the tie set on

Ticro!

$efault 54@5sA!

Tmicro Time duration

:? :s

:1 :.1s

F F

8?? 8?s


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$rdering o target cells

0a)er priorit) o

candidate cells

Static

priorit)2esource

available&

(

"o!er budget

margin

,)namic

priorit)

,)namic

priorit)


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#andover decision

eecution

#andover failure/

'tart #oFail*enal,ime

*enalount01

compare the difference bet(een ad2acent cell3s

priority and the

acceptable priority

,he punished cell o(ns

the highest priority/

*enalount4*enalount5

6

7

7

7

omplete handover flo(

8

R%ev9n:4R%ev9n:-

*enalty%ev!ffset ?*enaltyount4*enaltyount56

8

8

#oFail*enal,ime

overtimes

'creen the target cell

Relieve the target cell

of penalty

7

N

*enalty strategy o inter,cell handover ailure


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,MaI#o overtimes

#andover decision

'tart intra-cell

handover/

'tart #oFail*enal,ime

I#oount4

7

7

!ther handover 8

I#oount4I#oount56 ?

,MaI#o4

I#oount4MaI#o

'top starting intra-cellhandover

I#oount4MaI#o

7

8

7

8

!ther handover

re&uirements are satisfied/

7

8

8

*enalty strategy o intra,cell handover ailure


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ontents

$vervie! o handover

lo! o handover





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E06,0 intererence handover

dle )C:available in cellD

dle )C:available in cellD

415(1intererence

handoverintra,cellhandover

415(1intererence

handoverintra,cellhandover

415(1 quality

:andoverinter,cellhandover

415(1 quality

:andoverinter,cellhandover

E

N

(ecision o handover start

9n:InterfF


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E06,0 ualit) handover

(ecision o handover startAv2DualE0=HoElDualThs

Av2Dual,0=Ho,lDualThs


1 / Av20ev*ell&n( 2@0BV7M'*&n( > MA@&?C&MS7T@"27MA@&n(- "&n(((

8 / Av20ev*ell&n( Av20ev,0 > H$7MA2G'*7DEA0&n(

)hat is0. Ad+acent cells level must be larger than the minimum receive level set or it;3. Ad+acent cells level shall be larger than the sum o quality handover

threshold and the serving cells (1 level.


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E06,0 level handover

(ecision o handover startAv20evelE0=IHoEl0evThs

Av20evel,0=I Ho,l0evThs



8 / Av20ev*ell&n( Av20ev,0 > H$7MA2G'*70BVB0&n(

)hat is0. Ad+acent cells level must be larger than the minimum receive level set or it;3. Ad+acent cells level shall be larger than the sum o level handover threshold

and the serving cells (1 level.


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0ong /S-MS distance handover


Av(istanceH(istance)hreshold%)A'



)he only condition is that the ad+acent cells level is larger than the minimumreceive level set or it.

$adioenvironment

quality isnot

regarded asdecision

standard.

$adioenvironment

quality isnot

regarded asdecision

standard.

A##lication range

)his "ind o handover is usually used in net!or"s !ith long distance coverage.


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"/GT handover



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

2 / PBGT(n ) > !_MARGIN(n) )hat is

0 / Ad+acent cells level shall be larger than the minimum receivelevel set or it; 3 / ts #o!er budget value shall be larger than the *BG)handover threshold set or ad+acent cell.

Ma"e handover decision to each ad+acent cell in rotation;!hen an ad+acent cells *BG) value is higher than


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,irected retr)-decision o handover start

M' applies for ,#

$sable ,#

available/=ssignment success

Force disconnetionB

force handover and

ordering attempt

'uccessful force

disconnetionB force

handover and ordering

Directed retrys(itch open or not

Directed retry

7es

successful

7es

8o

unsuccessful

,# occupancy failure

8o


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,irected retr) handover

It ha66ens in the 6rocess of calling access; It dynaically adBusts call traffic )etween cells;

It can lower call loss rate;

Selection of target cells ust fulfill condition 8!

Get to "no! the lo! ointernal I e>ternal directed retry

:o! to control356G handover #riorityD

ts suggested that ordering #rocess be o#ened irstsince its eect is better than that o directed retry.


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"enalt) on directed retr) ailure

No candidatecells ound

Start thededicated timer

Ater timere>#ires

/rdercandidate cells

:andoverE

N %NH6 ailure'

Failure dueto radio lin"

#roblem(elete the

attem#t cells

3ndcandidate cell

:andover

E

N %NH6 or )60#ires give u# directed retry'

Candidatecells have no

radioresources BSC e>ternal

cells

BSC internal

cells

3ndcandida

te cell

:andoverE

Com#lete

N


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ontents

$vervie! o handover

lo! o handover




O


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E0 ast ading handover

This is a kind of algorith for saving handover due to U" level

decrease; It is fleDi)ly used in dense ur)an areas1 like icro&cells1 highways1

corners and slo6es1 where in&tie outgoing handovers are needed;

Selection of target cell shall fulfill condition 8;

Given condition 8 is fulfilled1 handover to relevant cellsF is 6referred!

M216"21

M286"28

M296"29

M246"24

*umber o consecutive

handover decisions &*(

(irectlyre#ort M$ to

B)S

* unavailable @

I t l U O l ▲


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Macro-micro handover

Handover trigger conditionsJ measured values o adjacent

cellKs signal strength is higher than thresholdC and this

reaches certain consecutive times.

Selection o target cellJ

*ondition 8 is fulfilled; "ayer relation with neigh)or cell ' NcellLayer ( is

"ower!

Av20evE0&n(= MacroMicroHoThs

Macrocell

MicrocellMicroce

ll

Serving cellmacrocell

)arget cellmicrocell

),


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Traic handover

0hen the serving cell suffers fro congestion1 for MS which has

esta)lished a call1 'S* will hand it over to an adBacent cellwhich can fulfill traffic handover conditions!

Ad+ust call traic in dierent cells to reach traic balance.

(ecision o handover start TH/us)"ercentTraicThs

K>cluding congested )C:s;

$egardless dynamic :$ anddynamic *()C:.

Selection o target cell

Condition 0 PBGT(n) > TrafficLevThs

I t l U O l ▲


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MS-started traic load handover

ItCs started )y MS*; Select at ost :uOfMS calls;

+andover fro high loaded cells to low loaded ones!

nter,BSC load ad+ustment;No data coniguration needed at radio side.

Note*recondition or this handover algorithm MSC starts theunction and BSC su##orts load re#ort.

Currently no manuacturer ma"es this unction o#en. DDDDD

I t l U O l ▲


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orced directed-shit handover

eatures

The last eans to adBust traffic; Mainly used in *O&'**+ cells;

.66lica)le

scenes?44M8544M cell of the

sae direction;

Target cell ust )e

forced firected shift

handover cell!



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orced directed-shit handover strateg)


"ath0oss&n(I=Ma0ossThs

TA&n(I=MaTAThs

Ma>)A)hs96 Ma>1oss)hs 08<

/nlybased

on*athloss

/nlybased

on)A

Selection o target cell

*BG) value must be larger than the dierence bet!een *BG)threshold and Ma>Force:o(i;

4sable resource in target cell must be larger than :oForce$es)hs;

)arget cell must be the one or dorced directed,shit handover.



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omparison bet!een orced directed-shit handover and

other t)pes o handover

ompared!ith "/GT

handover

Usually they are valid at the sae tie1 )ut ('GTs 6riority is higher

than that of forced directed&shift handover;

The MaD"ev$iff of forced directed&shift handover ust )e saller

than the value of reverse ('GT1 or (ing6ong handover will )e resulted!

ompared

!ithdirected

retr)

,orced directed&shift is the handover )etween two T*+s during call

6rocess;$irected retry is carried out when a66lying for T*+ during call

access!

ompared

!ith traic

handover

$ifferent trigger conditions @forced directed&shift handover is

triggered )y MS1 traffic handover is triggered )y 'S*!A

$ifferent handover flows!



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o-/H handover-subcell

)he irst subcell

)he second subcell

o-/H

Conigurationo subcell

Conigurationo subcell

arriers in different

fre&uency bands belong to

different subcells;

,he first subcell is

configured (ith "#.

o-channel cell

oncentric circle

advance technology;

'ubcells are allo(ed to

maCe po(er controlrespectively.



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o-/H handover trigger decision

(ecision o

handovertrigg

er

Based on#athloss

I)A

Based on C5

too small#athloss

I)A

too large#athloss

I)A

C5 good

C5 bad

*ath1ossL*ath1ossMin

And )AL SubCell)AMin

*ath1ossH *ath1ossMa>/r )AH SubCell)AMa>

C5H GoodCi)hs

C5L BadCi)hs

)hesecondsubcell

)heirst

subcell


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ontents

$vervie! o handover

lo! o handover






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$ptions o inter-s)stem &8G-EMTS6T,( handover strateg)

Han%o1e4 o

3A

p4e!e44e%

Han%o1e4 o 3A

N


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,escription o inter-s)stem &8G-EMTS6T,( handover strateg)

9G cell

preerre

d

8G cell

preerred

9G cell

inhibited

'nter-s)stem handover is inhibitedL handover algorithms are the

same as those o 8G.

6G handover decision

Valid decision Start 6G handover no more attem#t to 3G;

Null decision 3G handover decision I selection o target cell;

3G:andover decision

Valid decisionSaving handover

Null decision 6G handover decision I selection o target cell;

Select a 6G cell as candidate

try it i there is no usable radioresource available in 3G cell;

Non,saving handover 6G cells are not or candidates;



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DuestionsJ

(lease si6ly descri)e the relation )etween layer

and 6riority in handover algoriths;

(lease enuerate radio 6araeters of 9&


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gsm p&o training material for special subject-handover algorithms - zte

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