wcdma handover principle

7/18/2019 WCDMA Handover Principle

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Huawei Confidential. All Rights Reserved

WCDMA Handover Principle and

AnalysisISS ! ".#


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2Internal se

Why mobile systems needhandover?

It is decided by the characters ofmobile system:

$he %o&ility of !$he %o&ile syste% is co%posed &ycells which the coverage a&ility isli%ited.Providing the continuous service in%o&ile syste% is the &asic ele%ent in'oS.


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(&)ect(&)ect

Upon completion this course, you willbe able to:

The basic definitions of Handover The al orithms of handoverdecision

The handover flow

The parameters of handover


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!Internal se

Chapter "Chapter " Introduction of Handover Introduction of Handover

Chapter * Measure%ent of Handover

Chapter + $he ,asic HandoversChapter - ,lind Handover and

Direct Retry Algorith%


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$he Purpose of Handover $he Purpose of Handover

#rovidin the continuous service in mobile system is the basicelement in $o%&

The load balance: sharin the resource

The hierarchy divided by speed and service: hi h efficiency of usinresource


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'Internal se

$he ,asic Concepts of Handover $he ,asic Concepts of Handover

(ctive %et

)onitored %et*etected set+vent reportin

+vent reportin to #eriodic reportin#eriodic reportin

adio -in. / -0adio -in. %et / -%0

1ombination way:ma imum ratio combinationselection combination

The soft handover ain1#I1H%oft handover, softer handover, hard handover

lind handover


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$he Categories of Handover $he Categories of Handover

(ccordin to the si nalin characters:%oft handover /softer handover0Hard handover

(ccordin to the properties of source cell and tar et cellIntra5fre6uency handover Inter5fre6uency handover

Inter5mode handover /7** 859 T**0Inter5system handover /U)T% 859 %);1*)(2


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$he Characters of Different Handovers$he Characters of Different Handovers

Item %oft Handover Hard Handover

The numbers of -in active set afterhandover

%everal =ne

Interruption durinhandover o @es

The fre6uencies ofcells

=nly happenedin Intra5fre6uency cells

1an be happened inIntra5fre6uency cells orInter5fre6uency cells

1omparison between soft handover and hard handover:


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$he Characters of Different Handovers$he Characters of Different Handovers

*urin softer handover, the uplin. si nalin arecombined in ode by ma imum ratio combination, butdurin soft handover they are combined in 1 byselection combination&1ompare to later one, the ma imum ration combinationcan et more ain& %o the performance of ma imum

ration combination is better&

%ince softer handover is completed in ode , it do notconsume transport resource of Iub&

1omparison between soft handover and softer handover:


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RNC (WFMR)

NodeB

Softer Handover Softer Handover


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Hard Handover Hard Handover


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$hree Steps of Handover $hree Steps of Handover

*ecision

+ ecute

)easurement

)easurement)easurement control)easurement e ecution andthe result processinThe measurement report)ainly accomplished by U+

*ecisionased on )easurement

The application anddistribution of resource)ainly accomplished by

) in 1+ ecution

The process of si nalin%upport the failure drawbac.)easurement control refresh


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'uestions'uestions

The differences amon %oft handover,softer handover and hard handover Typical application scenarios


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Su%%arySu%%ary

This chapter focus on the purpose of handovers and thecate ories of handover in W1*)(&


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Chapter " Introduction of Handover

Chapter *Chapter * Measure%ent of Handover Measure%ent of Handover

Chapter + $he ,asic HandoversChapter - ,lind Handover and

Direct Retry Algorith%


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Chapter *Cha pter * Measure%ent of Handover Measure%ent of Handover

Section " Measure%ent control and

%easure%ent report

Section * $he &asic definitions of %easure%ent

Section + Intra fre/uency %easure%ent event

Section - Inter fre/uency and

inter syste% %easure%ent eventSection 0 ! internal %easure%ent


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Measure%ent Control and Measure%entMeasure%ent Control and Measure%entReportReport

)easurement 1ontrol

U+ UT (

)+(%U +)+ T 1= T =-

Measure%ent Control1 nor%al case


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Measure%ent Control and Measure%entMeasure%ent Control and Measure%entReportReport

)easurement report

U+ UT,(?

)+(%U,+)+?T ,+#=,T

Measure%ent report1 nor%al case


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$he ,asic Concepts of Measure%ent$he ,asic Concepts of Measure%ent

The measurement values of Handover Intra5fre6uency and inter5fre6uency: 1#I1H %1# 1#I1H+c; < #ath lossInter5fre6uency 1#I1H %1# 1#I1H +c; & ,(*I= -I?*+-+TI=? ,+%#=?%+

A&(-1(# release

2e Para%eters2ey Para%eters


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!AInternal se

2ey Para%eters2ey Para%eters

Handover decision threshold based on + speed

U+ should do soft handover when the speed of + service is lessthan the threshold&U+ should do intra5fre6uency hard handover when the speed of

+ service is reater than the threshold&The parameters about B* event:

time to tri er hysteresisThe parameters should be set accord with the $os


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"


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"BInternal se

$ , y$ , yHard Handover Hard Handover

1haractersThe wor.in fre6uency is different after handover The compressed mode needed if the U+ only has one receiver Usually, the timin re5initiation hard handover is used for hardhandover

(dvanta es1ompare to intra5fre6uency hard handover, the success

possibility is hi her The load balance amon cells with different fre6uencies1an reali e the reasonable confi uration for hierarchy cells

*isadvanta es1ompressed mode results in e tra radio resource occupied

The timin re5initiation hard handover increase the time ofhandover and the ris. of call drop (pplication scenarios

*isconnected covera eHandover based on loadHierarchy cells

$he Inter fre/uency Hard Handover Measure%ent$he Inter fre/uency Hard Handover Measure%ent


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"2Internal se

yy;alues and !vents;alues and !vents

The Inter5fre6uency hard handover measurement values)easurement values:

1#I1H %1# 1#I1H +c; >! C$I (> S! $ P+ RRC C(> >!$I( > S !$ P C(M P9!$ !

RRC Direct Retry 8II:RRC Direct Retry 8II:


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>"Internal se

(pplication scenarios /II0The soft handover area

cellB cell2

B

2

3

UE campingcell1 first

S oft h andov erare a

Signa ling Proce ss4" R RC C (>>! C$I( > R!' !S $* RRC C(> >!C$I (> S! $ P+ RRC C(> >!$I ( > S !$ P C( MP9!$ !

RRC Retry 2ey Para%etersRRC Retry 2ey Para%eters


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>'Internal se

* )a umber The ma imum allowed retry times for the direct retry moduleafter the initial failure

1sThreshold&When the si nal 6uality of a cell is hi her than this threshold,this cell will be included in the direct retry candidate set&

)in%i nal e6uiredThe basic access threshold described in %ection 2&2&>,namely the minimum re6uirement of the U+ form the receivin1#I1H +c; o density durin normal demodulation&

)a elatin TimeThe ma imum time that the (1H measurement report can

continue to be used for the direct retry candidate set&

RRC RedirectionRRC Redirection


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>4Internal se

(pplication scenariosThe si nalin connection is failed, and 1 retry is also failed&

Inter5fre6 cell

cellB

B

2

BJ

! ca% p ing c ell"first

%) cell

BJJSignal ing p roce ss4

" R RC C( >>!C $I(> R!' !S $* RRC C (>> !C$I( > R! ?!C $"@ ! initial the a ccess proc essafter cell r e.sele ction"@@ ! in itial th e acc ess p roce ssin 6SM cell after inter.s yste% cell r esele ction

RRC Direct Retry and DirectionRRC Direct Retry and Direction


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>>Internal se

The tri er condition should be the si nalin permittin failure

if con estion happed, the 1 connection si nalin is refused& (dvanta es and disadvanta es:

1 direct retry can ensure the time delay&1 direction is more fle ible, and can select to %) cell& ut

the time delay is lon er&

RA, Direct RetryRA, Direct Retry


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>AInternal se

(pplication scenarios

UT ( 1+--

%) 1+--

B 3

!

Signaling process

" RA, Assign%ent 8fro% C>:* SR>S relocation 8to C>:+ Handover fro% $RA> 8 Infor% !access to 6SM syste%:- Handover Co%plete 86SM %essage:

2

1

'uestions'uestions


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A


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ABInternal se

This chapter focus on 1 direct retry, 1 redirection, the

application scenarios of ( direct retry and blind handover&


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wcdma handover principle

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