WCDMA UE Behaviors in Idle Mode.pdf

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Course Code Product Product Version Course Version ISSUE

OWO114010 SingleRAN RNO

UO

SingleRAN5.0

Feature

Version 1.01

Developer/Modifier Time Approver New/Update

Ding Qi/53895 2010-03 New

Li Zhihai/131679 2011-08 Update

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WCDMA UE Behaviors in Idle Mode



Foreword

UE behaviors in idle mode include:

PLMN selection

System information reception

Cell selection and reselection

Location registration

Paging procedure

Access procedure



References

3GPP TS 22.011: Service Accessibility

3GPP TS 23.122: NAS Functions Related to Mobile Station

(MS) in Idle Mode

3GPP TS 24.008: Mobile Radio Interface Layer 3 Specification;

Core Network Protocols - Stage 3

3GPP TS 25.304: UE Procedures in Idle Mode and Procedures

for Cell Reselection in Connected Mode

3GPP TS 25.331: Radio Resource Control (RRC)

3GPP TS 31.102: Characteristics of The USIM Application



Objectives

Upon completion of this course, you will be able to:

Describe the working principles of the UE Behaviors in Idle

Mode feature

Perform parameters modification of the UE Behaviors in Idle

Mode feature



Contents

1. PLMN Selection

2. System Information Reception

3. Cell Selection and Reselection

4. Location Registration

5. Paging Procedure

6. Access Procedure



Contents

1. PLMN Selection




5. Paging Procedure

6. Access Procedure



Cell Search

UE does not have UTRAN carrier information:

In order to find a suitable cell to stay, UE will scan all the

frequencies in UTRAN. In each carrier, UE just need to find a

cell with best signal

UE has UTRAN carrier information:

UE will try whether the original cell is suitable to stay. If not,

UE still need to scan all the frequencies in UTRAN to find a

suitable cell in PLMN



Cell Search (Cont.)

Slot synchronization

Frame synchronization and code-group identification

Primary scrambling code identification



PLMN Selection



PLMN Selection (Cont.)

When the UE is switched on, or the coverage is restored,

then the UE selects the registered PLMN or its equivalent

PLMNs

If no registered PLMN or equivalent PLMNs is available,

or if registration fails, the UE performs one of the

following two procedures, depending on its operating

mode:

Automatic PLMN selection: the UE automatically selects a

PLMN according to the priority order

Manual PLMN selection: the UE shows all available PLMNs

to the subscriber. The subscriber then selects a PLMN



PLMN Selection (Cont.)

Automatic PLMN selection: UE can select a PLMN from the

Home PLMNs (HPLMNs) and roam in the Visited PLMN (VPLMN)

Selecting from the HPLMNs: UE maintains a list of allowed and

available PLMNs in priority order. When selecting a PLMN, the UE

searches for the PLMNs from the highest priority to the lowest

Roaming in the VPLMN: UE periodically searches for the HPLMN

and higher priority PLMNs for better services

Manual PLMN selection: UE maintains a list of allowed and

available PLMNs in priority order. When selecting a PLMN, the

UE indicates the list to the subscriber who will select a PLMN,

and then camps on the selected PLMN



Contents

1. PLMN Selection




5. Paging Procedure

6. Access Procedure



Structure of System Information

System information is organized as a tree, including:

MIB (Master Information Block)

SB (Scheduling Block)

SIB (System Information Block)



System Information

SIB1: contains the system information for NAS and the

timer/counter for UE

SIB2: contains the URA information

SIB3: contains the parameters for cell selection and cell re-

selection

SIB5: contains parameters for the common physical channels of

the cell

SIB7: contains the uplink interference level and the refreshing

timer for SIB7

SIB11: contains measurement controlling information



Reception of System Information

The UE shall read system information broadcast on a BCH

transport channel when the UE is in idle mode or in

connected mode, that is, in CELL_FACH, CELL_PCH, or

URA_PCH state



Contents

1. PLMN Selection




5. Paging Procedure

6. Access Procedure



Cell Selection

When the PLMN is selected and the UE is in idle mode,

the UE starts to select a cell to camp on and to obtain

services

There are four states involved in cell selection:

Camped normally

Any cell selection

Camped on any cell

Connected mode





Cell Selection (Cont.)

Two types of cell selection:

Initial cell selection

If no cell information is stored for the PLMN, the UE starts this

procedure

Stored information of cell selection

If cell information is stored for the PLMN, the UE starts this

procedure



Cell Selection Criteria

minqualqualmeasqual QQS

oncompensatirxlevrxlevmeasrxlev PQQS min

Criterion S is used by the UE to judge whether the cell is

suitable to camped on

Criterion S: Srxlev > 0 & Squal > 0, where:



Parameters of S Criterion

Qqualmin

Parameter name: Min quality level

Recommended value: -18, namely -18dB

Qrxlevmin

Parameter name: Min Rx level

Recommended value: -58, namely -115dBm



Parameters of S Criterion (Cont.)

MaxAllowedUlTxPower

Parameter name: Max allowed UE UL TX power

Recommended value: 24, namely 24dBm



Cell Reselection

The signal strength of both serving cell and neighboring

cells varies with the movement of a UE and so the UE

needs to select the most suitable cell to camp on. This

process is called cell reselection

Cell reselection process:

Measurement start criteria

Cell reselection criteria



Measurement Start Criteria

Intra-frequency measurement:

Squal ≤ Sintrasearch

↓

Qqualmeas − Qqualmin ≤ Sintrasearch

↓

Qqualmeas ≤ Qqualmin + Sintrasearch



Measurement Start Criteria (Cont.)

Inter-frequency measurement:

Squal ≤ Sintersearch

↓

Qqualmeas − Qqualmin ≤ Sintersearch

↓

Qqualmeas ≤ Qqualmin + Sintersearch



Measurement Start Criteria (Cont.)

Inter-RAT measurement:

Squal ≤ SsearchRATm

↓

Qqualmeas − Qqualmin ≤ SsearchRATm

↓

Qqualmeas ≤ Qqualmin + SsearchRATm



Parameters of Measurement Start Criteria

IdleSintrasearch

Parameter name: Intra-freq cell reselection threshold for

idle mode

Recommended value: 127, namely none

ConnSintrasearch

Parameter name: Intra-freq cell reselection threshold for

connected mode




Parameters of Measurement Start Criteria (Cont.)

IdleSintersearch

Parameter name: Inter-freq cell reselection threshold for

idle mode


ConnSintersearch

Parameter name: Inter-freq cell reselection threshold for

connected mode




Parameters of Measurement Start Criteria (Cont.)

SsearchRat

Parameter name: Inter-RAT cell reselection threshold




Measurement Start Criteria Description



Cell Reselection Criteria

Criterion R is used for intra-frequency, inter-frequency

and inter-RAT cell reselection

The cell-ranking criterion R is defined by:

nsoffsetnmeasn QQR,,

hystssmeass QQR ,



Hysteresis and Time Interval



Parameters of R Criteria

QualMeas

Parameter name: Cell Sel-reselection quality measure

Recommended value: CPICH_ECNO

Treselections

Parameter name: Reselection delay time

Recommended value: 1, namely 1s



Parameters of R Criteria (Cont.)

IdleQhyst1s

Parameter name: Hysteresis 1 for idle mode

Recommended value: 2, namely 4dB

ConnQhyst1s

Parameter name: Hysteresis 1 for connected mode





IdleQhyst2s

Parameter name: Hysteresis 2 for idle mode


ConnQhyst2s

Parameter name: Hysteresis 2 for connected mode





IdleQoffset1sn

Parameter name: IdleQoffset1sn


ConnQoffset1sn

Parameter name: ConnQoffset1sn





IdleQoffset2sn

Parameter name: IdleQoffset2sn


ConnQoffset2sn

Parameter name: ConnQoffset2sn




Contents

1. PLMN Selection




5. Paging Procedure

6. Access Procedure



Location Registration

The location registration includes:

Location update (for non-GPRS)

Route update (for GPRS)

The types of location registration:

Normal location registration

Periodic location registration

IMSI attach/detach(for non-GPRS)



Periodic Location Registration

Periodic location registration is controlled by a Periodic

Location Update timer (T3212, for non-GPRS operation)

or a Periodic Routing Area Update timer (T3312, for

GPRS operation)

T3212 is set through T3212 on the RNC side

T3312 is set on the CN side



IMSI Attach/Detach

The IMSI attach/detach process facilitates the fast

location registration of the UE in specific conditions

IMSI attach/detach is set through ATT on the RNC side



Parameters of Location Registration

T3212

Parameter name: Periodical location update timer [6min]

Recommended value: 10, namely 60min

ATT

Parameter name: Attach/detach indication

Recommended value: ALLOWED



Contents

1. PLMN Selection




5. Paging Procedure

6. Access Procedure



Paging Initiation

CN initiated paging:

Establish a signaling connection

UTRAN initiated paging:

Trigger the cell update procedure

Trigger reading of updated system information



Paging Type 1

If UE is in the idle or CELL/URA_PCH state, the paging

message will be transmitted on PCCH with paging type 1

CN RNC1 RNC2 NODEB1.1 NODEB2.1 UE

RANAPRANAP

RANAP RANAP

PCCH: PAGING TYPE 1

PAGING

PAGING

PCCH: PAGING TYPE 1



Paging Type 2

If UE is in CELL_DCH or CELL_FACH state, the paging

message will be transmitted on DCCH with paging type 2

CN SRNC UE

RANAPRANAP

PAGING

RRCRRCDCCH: PAGING TYPE 2



DRX Procedure

To reduce power consumption, the UE can read the

information from the PICH only at a particular time. This

is known as the Discontinuous Reception (DRX)

technology. The interval between two consecutive

periods of time is called DRX cycle

The value for the DRX paging cycle length is determined

as follows:

DRX Cycle Length ＝ MAX (2k, PBP) frames



DRX Procedure (Cont.)

The value of the Paging Occasion is determined as

follows:

Paging Occasion (CELL SFN) =

{(IMSI div K) mod (DRX cycle length div PBP)} * PBP

+ n * DRX cycle length + Frame Offset

Paging Occasion(CELL SFN) Case:




In FDD the UE shall monitor its paging indicator in the PICH

frame with SFN given by the Paging Occasion

The Page Indicator in the frame to use is calculated by using

the following formula:

Where, PI = (IMSI div 8192) mod NP

NP is the number of paging indicators in one PICH frame

NpNp

SFNSFNSFNSFNPIq mod144

144mod512/64/8/18




PICH

Associated S-CCPCH frame

PICH frame containing paging indicator

Through DRX, UE only listens to PICH at certain

predefined time. And UE will read the paging information

on SCCPCH if the paging indicator is 1

Time offset between PICH and SCCPCH:



Parameters of DRX

DRXCyclelenCoef

Parameter name: DRX cycle length coefficient

Recommended value: 6

PICHMode

Parameter name: PICH mode

Recommend value: V36



Parameters of DRX (Cont.)

MaccPageRepeatTimes

Parameter name: Number of page re-TX




Contents

1. PLMN Selection




5. Paging Procedure

6. Access Procedure



Two Working Modes of UE

Idle mode:

After turning on, UE will stay in idle mode

Connected mode:

UE will switch to connected mode which could be

CELL_FACH state or CELL_DCH state from the idle mode

After releasing RRC connection, UE will switch to the idle

mode from the connected mode



Random Access Procedure

Definition:

Random access procedure is initiated by UE in order to get

service from the system. Meanwhile, the access channels

are allocated to the UE by system



Random Access Channel

AICH accessslots

10 ms

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4p-a

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4

PRACHaccess slots

SFN mod 2 = 0 SFN mod 2 = 1

10 ms

Access slot set 1 Access slot set 2



RACH Sub-Channels

SFN mod 8

Random access sub-channels number

0 1 2 3 4 5 6 7 8 9 10 11

0 0 1 2 3 4 5 6 7

1 12 13 14 8 9 10 11

2 0 1 2 3 4 5 6 7

3 9 10 11 12 13 14 8

4 6 7 0 1 2 3 4 5

5 8 9 10 11 12 13 14

6 3 4 5 6 7 0 1 2

7 8 9 10 11 12 13 14

The access slots of different RACH sub-channels are illustrated

by the following table:



Random Access Channel Case

Sub Channels how to use Access Slots ?

p-p



Access Service Class

The PRACH resources can be classified into several ASCs,

so as to provide RACH applications with different

priorities



Access Control

“Access Control” is used by network operators to prevent

overload of radio access channels under critical

conditions

Access class 0 ~ Access Class 9

Access class 11 ~ Access Class 15

Access class 10



Mapping between AC and ASC

The AC-ASC mapping information is optional and used

for the System Information Block 5 (SIB5) only

AC-ASC mapping case



Random Access ProcedureSTART

Choose a RACH sub channel fromavailable ones

Get available signatures

Set Preamble Retrans Max

Set Preamble_Initial_Power

Send a preamble

Check the corresponding AI

Change message part power by p-m based on preamble power

Set physical status to be RACHmessage transmitted Set physical status to be Nack

on AICH received

Choose a access slot again

Counter > 0 & Commanded Preamble power- maximum allowed power < 6

dB

Choose a signature and increase preamble transmit power

Set physical status to be Nackon AICH received

Get negative AI

No AI

Report the physical status to MAC

END

Get positive AI

The counter of preamble retransmit Subtract by 1, Commanded preamble power

increased by Power Ramp Step

N

Y

Send the corresponding message part





RRC Connection Message

Typical RRC connection messages:

RRC_CONNECTION_REQUEST

RRC_CONNECTION_SETUP

RRC_CONNECTION_SETUP_COMPLETE

RRC_CONNECTION_RELEASE



UE Timers and Constants in Idle Mode

T300

Parameter name: Timer 300 [ms]

Recommended value: D2000, namely 2s

N300

Parameter name: Constant 300




UE Timers and Constants in Idle Mode (Cont.)



RRC Connection Establish Channel Type and Bit Rate RrcCause

Parameter name: Cause of RRC connection establishment

Recommended value: refer to next page

SigChType

Parameter name: Channel type for RRC establishment

Recommended value: refer to next page






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WCDMA UE Behaviors in Idle Mode.pdf