04 cell update

RAN Feature Description Table of Contents

Table of Contents

Chapter 4 Cell Update.................................................................................................................4-1

4.1 Introduction...................................................................................................................... 4-1

4.1.1 Definition...............................................................................................................4-1

4.1.2 Purposes...............................................................................................................4-1

4.1.3 Terms and Abbreviations.......................................................................................4-1

4.2 Availability........................................................................................................................ 4-3

4.2.1 Network Elements Involved...................................................................................4-3

4.2.2 Software Releases................................................................................................4-4

4.2.3 Miscellaneous........................................................................................................4-4

4.3 Impact.............................................................................................................................. 4-4

4.3.1 Impact on System Performance............................................................................4-4

4.3.2 Impact on Other Features......................................................................................4-4

4.4 Restrictions...................................................................................................................... 4-4

4.5 Technical Description.......................................................................................................4-4

4.5.1 Cell Update Configuration Model...........................................................................4-4

4.5.2 Basic Types...........................................................................................................4-5

4.5.3 Basic Signaling Procedure of Cell Update...........................................................4-13

4.5.4 Signaling Procedure of Cell Update with SRNS Relocation................................4-14

4.5.5 Signaling Procedure of Cell Update with Cause Radio Link Failure....................4-15

4.6 Capabilities....................................................................................................................4-16

4.7 Implementation..............................................................................................................4-16

4.7.1 Enabling Cell Update...........................................................................................4-16

4.7.2 Reconfigure Cell Update.....................................................................................4-16

4.7.3 Disabling Cell Update..........................................................................................4-17

4.8 Maintenance Information................................................................................................4-18

4.8.1 Alarms.................................................................................................................4-18

4.8.2 Counters..............................................................................................................4-18

4.9 References..................................................................................................................... 4-19

Huawei Technologies Proprietary

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RAN Feature Description List of Figures

List of Figures

Figure 4-1 Cell update configuration model..........................................................................4-5

Figure 4-2 Basic signaling procedure for cell update..........................................................4-13

Figure 4-3 Signaling procedure for cell update with SRNS allocation.................................4-14

Figure 4-4 Signaling procedure for cell update with cause radio link failure.......................4-15


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RAN Feature Description List of Tables

List of Tables

Table 4-1 NEs required for cell update..................................................................................4-3

Table 4-2 RAN products and related versions.......................................................................4-4

Table 4-3 Commands for the reconfiguration on the RNC side...........................................4-17

Table 4-4 Cell update counters............................................................................................4-18


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RAN Feature Description Chapter 4 Cell Update

Chapter 4 Cell Update

4.1 Introduction

4.1.1 Definition

Cell update is used to:

Update a UE information on the UTRAN side when the location of the UE

changes

Monitor the RRC connection

Switch the RRC connection state

Report faults and transmit information

Cell update procedure is initiated by a UE.

4.1.2 Purposes

Cell update enables UTRAN to manage a UE’s behavior. It can be applied in mobility,

cell reselection and paging procedures, With cell update feature, it can:

Enable UTRAN to monitor a UE’s status in CELL_FACH or CELL_PCH state by

periodical cell update;

Let UTRAN know a UE’s current camping cell after the UE re-enters the service

area, while the UE is in CELL_PCH or CELL_FACH state;

Let the UTRAN know in time which cells are in the active set after cell reselection

Trigger a UE state transition from CELL_PCH, or URA_PCH state, to

CELL_FACH state when network is paging the UE;

To let the UE which requires the uplink data transmission transit from

CELL_PCH or URA_PCH state to CELL_FACH state;

Enable a UE with radio link failure to reestablish connection;

Enable the RNC release the RRC connection of the UE or reestablish a RLC

entity in the case of RLC unrecoverable error.

4.1.3 Terms and Abbreviations

I. Terms

Term Description

CELL_DCHAn RRC connected mode in which DCCH and, if configured, DTCH

are available. DCCH and DTCH are mapped to DCH.


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Term Description

CELL_FACH

An RRC connected mode in which DCCH and, if configured, DTCH

are available. DCCH and DTCH are mapped to RACH/FACH. The

RNC records the cells in the active set of the UE.

CELL_PCHAn RRC connected mode where neither DCCH nor DTCH is

available.

URA_PCHAn RRC connected mode where neither DCCH nor DTCH is

available.

II. Abbreviations

Abbreviation Full Spelling

3GPP Third Generation Partnership Project

AM Acknowledged Mode

CCCH Common Control Channel

CN Core Network

CPICH Common Pilot Channel

DCCH Dedicated Control Channel

DCH Dedicated Channel

DRNC Drift RNC

DTCH Dedicated Traffic Channel

FACH Forward Access Channel

IE Information Element

LMT Local Maintenance Terminal

MML Man Machine Language

PCH Paging Channel

RACH Random Access Channel

RANAP Radio Access Network Application Part

RB Radio Bearer


2


Abbreviation Full Spelling

RL Radio Link

RLC Radio Link Control

RNC Radio Network Controller

RNS Radio Network System

RNTI Radio Network Temporary Identifier

C-RNTI Cell RNTI

S-RNTI Serving RNC RNTI

RRC Radio Resource Control

RSCP Received Signal Code Power

SRNC Serving Radio Network Controller

SRNS Serving Radio Network System

UE User Equipment

URA UTRAN Registration Area

UTRAN Universal Terrestrial Radio Access Network

4.2 Availability

4.2.1 Network Elements Involved

Table 4-1 describes the NEs involved with cell update.

Table 4-1 NEs required for cell update

UE NodeB RNCMSC

ServerMGW SGSN GGSN HLR

√ √ √ - - - - -

Note:

–: not required

√: required


3


Note:

This chapter describes only the availability of the NodeB and the RNC.

4.2.2 Software Releases

Table 4-2 describes the versions of RAN products that support cell update.

Table 4-2 RAN products and related versions

Product Version

RNC BSC6800 V100R002 and later releases

NodeB

DBS3800 V100R005 and later releases

BTS3812A V100R005 and later releases

BTS3812E V100R005 and later releases

4.2.3 Miscellaneous

None.

4.3 Impact

4.3.1 Impact on System Performance

Frequent cell update may increase network signaling load and consume more UE

battery.

4.3.2 Impact on Other Features

None.

4.4 Restrictions

None.

4.5 Technical Description

4.5.1 Cell Update Configuration Model

The configuration model for Cell Update is as show in Figure 4-2.


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Hysteresis 1 for connect mode

Hysteresis 2 for connect mode

Cell Sel-reselection quality measure

Min quality level

CellClassGlobalParaClass

RNC

RadioClass

CONNMODETIMER.Class CELLSELRESEL.Class

Timer 305

Timer 307

Timer 313

Constant 313

Constant 315

Timer 302

Constant 302

Figure 4-2 Cell update configuration model

4.5.2 Basic Types

Cell update may be triggered by the following causes:

Periodical Cell Update

Cell Reselection

Paging Response

Uplink Data Transmission

Radio Link Failure

Re-entering Service Area

RLC Unrecoverable Error

I. Periodical Cell Update

Upon entering CELL_FACH or CELL_PCH state, a UE starts the T305 (Timer 305). If

T305 expires, the UE performs cell update with the cause "periodical cell update".

Correspondingly, RNC starts T305 for the UE in CELL_FACH or CELL_PCH state.

Upon receiving a CELL UPDATE message with this cause, RNC restarts T305 for this

UE.


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Parameter name Timer 305

Parameter ID T305

GUI range INFINITY, D5, D10, D30, D60, D120, D360,

D720

Physical range& unit Infinity, 5, 10, 30, 60, 120, 360, 720 (min)

Default value D10

Optional / Mandatory Optional

MML command SET CONNMODETIMER

Description:

T305 is started after the UE receives CELL UPDATE CONFIRM or URA UPDATE

CONFIRM in CELL_FACH, URA_PCH or CELL_PCH state. T305 is stopped after

the UE enters another state. When T305 expires, the UE transmit CELL UPDATE

if T307 is not activated and the UE detects "in service area". Otherwise, if

T307(Time 307) is not active, start T307.

T305 should be set larger than T302*N302(T305>T302*N302),UE can obtain the

value from SIB1.


Parameter ID T307

GUI range D5, D10, D15, D20, D30, D40, D50

Physical range& unit 5, 10, 15, 20, 30, 40, 50 (s)

Default value 30



Description:

T307 is started after T305 has expired and the UE detects "out of service area".

T307 is stopped after the UE detects "in service area". The UE enters idle mode

upon expiry.


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II. Cell Reselection

If a UE in CELL_FACH or CELL_PCH state reselects a new cell, it performs cell

update with the cause "cell reselection".

Upon receiving a CELL UPDATE message with this cause, RNC updates the camping

cell of the UE.

Hysteresis 1 for connect mode, Hysteresis 2 for connect mode, Cell Sel-

reselection quality measure, Min quality level are related to cell update procedure

with cause ”cell reselection”, they can be set by MML command.:

Parameter name Hysteresis 1 for connect mode

Parameter ID CONNQHYST1S

GUI range 0–20

Physical range& unit 0–40; step: 2 (dB)

Default value 2


MML command MOD CELLSELRESEL

Description:

The hysteresis value in connected mode for serving FDD cells when the quality

measurement for cell selection and reselection is set to CPICH RSCP. It is related

to the slow fading feature of the area where the cell is located. The greater the

slow fading variance is, the greater this parameter is.


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Parameter name Hysteresis 2 for connect mode

Parameter ID CONNQHYST2S

GUI range 0–20

Physical range& unit 0–40; step: 2 (dB)

Default value Hysteresis 1 for connect mode



Description:

The hysteresis value in connected mode for serving FDD cells when the quality

measurement for cell selection and reselection is set to CPICH Ec/N0. It is related

to the slow fading feature of the area where the cell is located. The greater the

slow fading variance is, the greater this parameter is.

Note:

This can be used only when parameter QualMeas is set to CPICH_ECNO.

Parameter name Cell Sel-reselection quality measure

Parameter ID QUALMEAS

GUI range CPICH_ECNO(CPICH Ec/N0),

CPICH_RSCP(CPICH RSCP)

Physical range& unit None

Default value CPICH_ECNO



Description:

This parameter can be set to CPICH Ec/N0 or CPICH RSCP.


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Parameter name Min quality level

Parameter ID QQUALMIN

GUI range -24–0

Physical range& unit -24–0 (dB)

Default value -18



Description:

The minimum required quality level corresponding to CPICH Ec/No. The UE can

camp on the cell only when the measured CPICH Ec/No is greater than the value

of this parameter.

III. Paging Response

If a UE in URA_PCH or CELL_PCH state receives a PAGING TYPE 1 message, it

performs cell update with the cause "paging response".

Upon receiving a CELL UPDATE message with this cause, RNC sends a CELL

UPDATE CONFIRM message to the UE and transits the UE to CELL_FACH state.

IV. Uplink Data Transmission

If a UE in URA_PCH or CELL_PCH state has uplink data to be transmitted, it

performs cell update with the cause "uplink data transmission".

Upon receiving a CELL UPDATE message with the this cause, RNC sends a CELL

UPDATE CONFIRM message to the UE and transits the UE to CELL_FACH state.

V. Radio Link Failure

If a UE in CELL_DCH state detects that the criteria for radio link failure are met, it

performs cell update with the cause "radio link failure".

Upon receiving a CELL UPDATE message with this cause, RNC deletes the current

radio link, reestablishes a new radio link, and sends a CELL UPDATE CONFIRM to

the UE with the parameters of the new radio link. Then the UE can re-establish

connection on the new radio link.

Some timers and constants are related to the criteria for radio link failure, they can be

set by MML command. Timer 313, Constant 313, Constant 315 are described as

follows:


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Parameter ID T313

GUI range 0–15

Physical range& unit 0–15 (s)

Default value 3



Description:

T313 is started after the UE detects N313 consecutive "out of sync" indications

from L1. T313 is stopped after the UE detects N315 consecutive "in sync"

indications from L1. It indicates Radio Link (RL) failure upon expiry.

Parameter name Constant 313

Parameter ID N313

GUI range D1, D2, D4, D10, D20, D50, D100, D200

Physical range& unit 1, 2, 4, 10, 20, 50, 100, 200

Default value D50



Description:

Maximum number of successive "out of sync" received from L1


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Parameter ID N315

GUI range D1, D2, D4, D10, D20, D50, D100, D200, D400, D600,

D800, D1000

Physical range& unit 1, 2, 4, 10, 20, 50, 100, 200, 400, 600, 800, 1000

Default value D1



Description:

Maximum number of successive "in sync" received from L1 during T313 is

activated

VI. Re-entering Service Area

If a UE moves out of the service area, and then re-enters the service area, it performs

cell update with the cause "re-entering service area".

Upon receiving a CELL UPDATE message with this cause, the RNC updates the

camping cell of the UE.

VII. RLC Unrecoverable Error

If a UE detects an RLC unrecoverable error in an AM RLC entity, the UE performs cell

update with the cause "RLC unrecoverable error".

If the CELL UPDATE message indicates that this error occurred on RB2, RB3 or RB4

in the UE, the RNC releases the RRC connection of the UE.

If the CELL UPDATE message indicates that this error occurred on RBn (n>4) in the

UE, the RNC reestablishes an RLC entity for the corresponding RB.

Timer 302,Constant 302,Counter V302 are related to all cell update procedures,

T302 and N302 are described as follows:


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Parameter ID T302

GUI range D100, D200, D400, D600, D800, D1000, D1200, D1400,

D1600, D1800, D2000, D3000, D4000, D6000, D8000

Physical range& unit 100, 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800,

2000, 3000, 4000, 6000, 8000(ms)

Default value D2000



Description:

T302 is started after the UE sends the CELL UPDATE or URA UPDATE message

and is stopped after the UE receives the CELL UPDATE CONFIRM or URA

UPDATE CONFIRM message. The CELL UPDATE or URA UPDATE message is

resent upon the expiry of the timer if V302<= N302; otherwise, the UE enters idle

mode.

Note: V302 is a counter for UE. It is reset when initiating the Cell update or URA update

procedure and incremented upon expiry of T302. When V302 > N302 the UE enters idle

mode.


Parameter ID N302

GUI range 0–7

Physical range& unit None

Default value 3



Description:

Maximum number of retransmissions of CELL UPDATE or URA UPDATE

Configuration Rule and Restriction:


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None.

Recommendation:

Usually, the default values of the cell update parameters are used. Resetting the

parameters is unnecessary.

4.5.3 Basic Signaling Procedure of Cell Update

Figure 4-3 shows the basic signaling procedure for cell update.

UE

1.CELL UPDATE

2.CELL UPDATE CONFIRM

3.RESPONSE MESSAGE

RNC

Figure 4-3 Basic signaling procedure for cell update

The basic signaling procedure is described as follows:

1) The UE sends the RNC a CELL UPDATE message including a cause in the “Cell

update cause” IE.

2) The RNC performs the corresponding processing, and then sends the UE a

CELL UPDATE CONFIRM message.

3) According to related IEs in the received message, the UE may respond with one

of the following messages:

UTRAN MOBILITY INFORMATION CONFIRM

PHYSICAL CHANNEL RECONFIGURATION COMPLETE

TRANSPORT CHANNEL RECONFIGURATION COMPLETE

RADIO BEARER RECONFIGURATION COMPLETER

RADIO BEARER RELEASE COMPLETE


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4.5.4 Signaling Procedure of Cell Update with SRNS Relocation

Figure 4-1 shows the signaling procedure for inter-RNS cell update with SRNS

relocation, from RNC 1 to RNC 2.

RNC1 RNC2CNUE

3. RELOCATION REQUIRED4. RELOCATION REQUEST

5. RELOCATION REQUEST ACK

6. RELOCATION COMMAND

9. CELL_UPDATE_CONFIRM

8. RELOCATION DETECT

11. RELOCATION _COMPLETE

2. UPLINK SIGNALLING TRANSFER INDICATION

7. RELOCATION COMMIT

10. PHYSICAL_CHANNEL_RECONFIGURATION_COMPLETE

12. IU RELEASE COMMAND

13. IU RELEASE COMPLETE

EST RAB, in CELL_FACH or CELL_PCH state

1. CELL UPDATE

Figure 4-1 Signaling procedure for cell update with SRNS allocation

The signaling procedure is described as follows:

The UE sets up an RRC connection on RNC 1. The UE is in CELL_FACH or

CELL_PCH state. Here, RNC 1 is the serving RNC (SRNC) and RNC 2 is the drift

RNC (DRNC).

1) The UE reselects a cell of RNC 2, and sends RNC 2 a CELL UPDATE message.

2) RNC 2 allocates a C-RNTI and a D-RNTI for the UE. RNC 2 forwards the CELL

UPDATE message received from CCCH to RNC 1 through an UPLINK

SIGNALLING TRANSFER INDICATION message. The message includes the

target RNC-ID, allocated C-RNTI and D-RNTI.

3) RNC 1 sends the CN a RELOCATION REQUIRED message, requesting SRNS

relocation.

4) The CN sends RNC 2 a RELOCATION REQUEST message.


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5) RNC 2 prepares L2 resources for RNC 1 relocation, and then sends the CN a

RELOCATION REQUEST ACK message.

6) The CN sends RNC 1 a RELOCATION COMMAND message, notifying RNC 1

that SRNS relocation starts.

7) RNC 1 completes related preparations such as stopping signaling and traffic

RLCs, and then sends RNC 2 a RELOCATION COMMIT message, requesting

RNC 2 to start the relocation.

8) RNC 2 sends the CN a RELOCATION DETECT message, notifying the CN that

the relocation starts. Then RNC 2 performs related operations such as L2

configuration.

9) RNC 2 sends the UE a CELL UPDATE CONFIRM message in the new cell,

including the old S-RNTI and SRNC ID as well as the new S-RNTI, SRNC-ID,

and C-RNTI.

10) The UE sends RNC 2 an RRC message, PHYSICAL CHANNEL

RECONFIGURATION COMPLETE, confirming the relocation succeeds.

11) RNC 2 sends the CN a RELOCATION COMPLETE message, allocates a new S-

RNTI to the UE, and becomes the new SRNC.

12) The CN sends RNC 1 an IU RELEASE COMMAND message, requesting RNC 1

to release the Iu interface resource related to this UE.

13) RNC 1 sends the CN an IU RELEASE COMPLETE message.

4.5.5 Signaling Procedure of Cell Update with Cause Radio Link Failure

Figure 4-1 shows the signaling procedure for cell update with cause radio link failure.


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Old NodeB RNCUE

2. RADIO LINK SETUP REQUEST

1. CELL UPDATE

New NodeB

3.RADIO LINK SETUP RESPONSE

4.ALCAP IUB BEARER SETUP

5.RADIO LINK DELETION REQUEST

6.RADIO LINK DELETION RESPONSE

7.ALCAP IUB BEARER RELEASE

8.CELL UPDATE CONFIRM

9.PHYSICAL CHANNEL RECONFIGURATION COMPLETE

Figure 4-1 Signaling procedure for cell update with cause radio link failure

When receiving a cell update message, the RNC establishes a new RL in this cell that

is indicated in the cell update message and deletes the old RL.

If the first attempt to re-establish the RL fails, the RRC connection will be released.

This procedure is supported for both CS and PS RAB.

For PS RAB, this procedure is supported for both DCH and HSDPA bearer.

More detailed description of this procedure as follows:

1) The UE initiates the re-establishment of the RRC connection with the new cell by

sending Cell Update message on CCCH.

2) The RNC allocates radio resources in the new cell and sends NBAP message

RADIO LINK SETUP REQUEST to the new NodeB.

3) Node B allocates resources, and responds with NBAP message RADIO LINK

SETUP RESPONSE.

4) RNC initiates set-up of IUB Data Transport bearer using ALCAP protocol.

5) RNC initiates release of IUB Data Transport bearer using ALCAP protocol and

also release of IUB Radio resource using NBAP RADIO LINK DELECTION

procedure.

6) RNC prepares a CELL UPDATE CONFIRM message and send to UE on CCCH.

7) UE re-establishment radio connection in new cell and send PHYSICAL

CHANNEL RECONFIGURATION COMPLETE message to RNC, and then re-

establishment of radio connection is completed.


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Besides, if both new cell and old cell belong to one NodeB, the procedure is similar

except that the RADIO LINK SETUP procedure described above will be replaced by

RADIO LINK ADDITION procedure.

4.6 Capabilities

None.

4.7 Implementation

4.7.1 Enabling Cell Update

This feature does not need extra hardware or initialization. It takes effect

automatically.

For the network planning or optimization, the data can be adjusted on the RNC LMT

as required. Generally default value of the related parameters is recommended to be

used.

4.7.2 Reconfigure Cell Update

I. Parameter Reconfiguration on the RNC Side

Table 4-1 describes the commands used for the reconfiguration on the RNC side.

Table 4-1 Commands for the reconfiguration on the RNC side

Function Command

About UE timers and

constants in connected

mode

To query the UE timers and

constants in connected mode

LST

CONNMODETIMER

To set the UE timers and

constants in connected mode

SET

CONNMODETIMER

About the cell selection

and reselection

information

To query the cell selection and

reselection informationLST CELLSELRESEL

To add the cell selection and

reselection informationADD CELLSELRESEL

To modify the cell selection

and reselection informationMOD CELLSELRESEL

To remove the cell selection

and reselection informationRMV CELLSELRESEL


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II. Parameter Reconfiguration on the NodeB Side

None.

III. Examples

Before data configuration on RNC LMT, use the related LST command to check

related information. Only after recording the original data can you modify the

parameters.

//Set the period of cell update initiated by the UE in CELL_FACH or

CELL_PCH state to 5 minutes.

SET CONNMODETIMER: T305=D5;

//Set T313 and N313 to greater values and N315 a smaller value, so that

cell update with the cause “RL FAILURE” is not easier to occur.

SET CONNMODETIMER: T313=3, N313=D50, N315=D1;

//Set the Min quality level to a smaller value, such as –21, to make it

easier for cell update with the cause of “cell reselection” to reselect

cell 3.

MOD CELLSELRESEL: CELLID=3, QUALMEAS=CPICH_RSCP, QQUALMIN=-21;

4.7.3 Disabling Cell Update

Cell update can be set and reconfigured, but not disabled.

4.8 Maintenance Information

4.8.1 Alarms

None.

4.8.2 Counters

Cell update counters belong to CELL->CELLUPDATE.Cell, where CELL is

measurement object type, and CELLUPDATE.Cell is measurement unit.

Table 4-2 lists the cell update counters.

Table 4-2 Cell update counters

Item Description

VS.CellUpdt.AttPrd Number of cell updates due to periodic cell

update

VS.CellUpdt.AttResel Number of cell updates due to cell reselection


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Item Description

VS.CellUpdt.AttRsaNumber of cell updates due to reentering

service area

VS.CellUpdt.AttPage Number of cell updates due to paging response

VS.CellUpdt.AttULDatTrsfNumber of cell updates due to uplink data

transfer

VS.CellUpdt.AttErrRLCNumber of cell updates due to RLC

unrecoverable error

RRC.AttConnReEstab.RFLoss Number of cell updates due to radio link failure

VS.CellUpdt.SuccUpdNumbers of successful cell updates due to

successful update

VS.CellUpdt.SuccPrdNumbers of successful cell updates due to

periodic cell update

VS.CellUpdt.SuccReselNumbers of successful cell updates due to cell

reselection

VS.CellUpdt.SuccRsaNumbers of successful cell updates due to

reentering service area

VS.CellUpdt.SuccPageNumbers of successful cell updates due to

paging response

VS.CellUpdt.SuccULDatTrsfNumbers of successful cell updates due to

uplink data transfer

VS.CellUpdt.SuccErrRLCNumbers of successful cell updates due to RLC

error

RRC.SuccConnReEstabNumbers of successful cell updates due to

radio link failure

VS.CellUpdt.AttConfNumber of CELL UPDATE CONFIRM

messages from SRNC

RRC.FailConnReEstab.NoReplyNumber of unsuccessful cell updates due to

radio link failure (no response)

VS.CellUpdt.SuccRRCRelNumber of RRC connection releases due to cell

update failure


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4.9 References

3GPP TS 25.331 "Radio Resource Control (RRC); protocol specification"

3GPP TS 25.931 "UTRAN Functions, Examples on Signaling Procedures"

3GPP TS 25.413 "UTRAN Iu interface RANAP signaling"


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04 cell update

Documents

physical range

slow fading variance

slow fading feature

ran feature description

uplink data transfer

radio link failure

ura update message

rlc unrecoverable error