blind handover and directed retry huawei

8/10/2019 Blind Handover and Directed Retry Huawei

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HUAWEI TECHNOLOGIES CO., LTD. Page 93HUAWEI

Contents

Chapter1Introduction:GSMvs.WCDMA

Chapter2HandoverMeasurement

Chapter3BasicHandovers

Chapter4BlindHandoverandDirectedRetry

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DRD


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RRC DRD


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RAB DRD


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RAB DRD


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ScopeandTriggeringConditions

l

l

l

l

RRC Directed Retry

[The initial signaling connection is established, and the cell request is

rejected.

RRC Redirection

[The initial signaling connection is established, the cell request is

rejected, and the RRC directed retry fails. (Directed retry has a higher

priority than redirection. When the directed retry fails, redirection istriggered after the cell request is rejected.)

RAB Directed Retry

[The signaling connection is successful, but services fail to be

established.

Blind Handover

[Inter-frequency load balancing (blind handover to inter-frequency cells)[RRC Directed Retry

[RAB Directed Retry

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MoreInformationAbouttheRRCDirectedRetry

andRedirection

l

l

The triggering condition is that the signaling access grant fails.

[If no access grant is performed (directly accepted) for the signaling,

the algorithm fails. The algorithm is effective during congestion.

[If access grant is performed for the signaling, the possibility for

triggering the RRC directed retry and redirection is low. Only when

cell congestion occurs, the possibility is high.Comparison of advantages and disadvantages

[For the RRC directed retry, subscribes feel shorter delay.

[RRC redirection is more flexible and can be used to reselected to

the GSM cell. Subscribers, however, feel longer delay.

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RRCDirectedRetry(1)l Scenario (1)

[Between inter-frequency overlapped coverage cells

2

cell1

1

cell2

3

UE initial camping cell

Inter-frequency overlapped

coverage cell of Cell1

Signaling process:

1RRCCONNECTIONREQUEST

2RRCCONNECTIONSETUP

3RRCCONNETIONSETUPCOMPLETE

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RRCDirectedRetry(2)

l Scenario (2)

[Between intra-frequency cells, and the UE is in the soft handover area

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cell1

Soft handover area Intra-frequency neighboring cell of Cell1

cell2

2

Signaling process:

1RRCCONNECTIONREQUEST

2RRCCONNECTIONSETUP

3RRCCONNETIONSETUPCOMPLETE

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RRCRedirection

l

Inter-freq cell

cell1

1

2

1


Scenario

[The UE fails to initiate signaling connection, and the RRC directed retry

fails.

GSM cell

1 Signaling process:1RRCCONNECTIONREQUEST

2RRCCONNECTIONREJECT

1TheUEinitiatesaccesstothe

specifiedcellofotherfrequenciesafter

cellreselection.

1TheUEinitiatesaccesstothe

specifiedGSMcellafterinter-RATcellreselection

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RABDirectedRetryl Scenario

1 3

4

Signaling process:

1RABAssignment(fromCN)

2SRNSrelocation(toCN)

3HandoverfromUTRAN(InformUE

accesstoGSMsystem)

4HandoverComplete(GSMmessage)

2

CN

GSM CELL

UTRAN CELL

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blind handover and directed retry huawei

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