CE_TMO18090 BSS B10-B11 Telecom Evolution.pdf

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BSS B10-B11 Telecom Evolutions - Page 1All Rights Reserved Alcatel-Lucent @@YEAR

All Rights Reserved Alcatel-Lucent @@YEAR

Base Station Subsystem

BSS B10-B11 Telecom Evolutions

STUDENT GUIDE

TMO18090 Issue 1.0

All rights reserved Alcatel-Lucent @@YEARPassing on and copying of this document, use and communication of its

contents not permitted without written authorization from Alcatel-Lucent


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BSS B10-B11 Telecom EvolutionsBase Station Subsystem

2

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3

Terms of Use and Legal Notices

Switch to notes view!1. Safety WarningBoth lethal and dangerous voltages may be present within the products used herein. The user is strongly advised not to

wear conductive jewelry while working on the products. Always observe all safety precautions and do not work on the

equipment alone.

The equipment used during this course may be electrostatic sensitive. Please observe correct anti-static precautions.

2. Trade Marks

Alcatel-Lucent and MainStreet are trademarks of Alcatel-Lucent.

All other trademarks, service marks and logos (Marks) are the property of their respective holders, including Alcatel-

Lucent. Users are not permitted to use these Marks without the prior consent of Alcatel-Lucent or such third party owning

the Mark. The absence of a Mark identifier is not a representation that a particular product or service name is not a Mark.

Alcatel-Lucent assumes no responsibility for the accuracy of the information presented herein, which may be subject to

change without notice.

3. Copyright

This document contains information that is proprietary to Alcatel-Lucent and may be used for training purposes only. No

other use or transmission of all or any part of this document is permitted without Alcatel-Lucents written permission, andmust include all copyright and other proprietary notices. No other use or transmission of all or any part of its contents may

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Use or transmission of all or any part of this document in violation of any applicable legislation is hereby expressly

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User obtains no rights in the information or in any product, process, technology or trademark which it includes or

describes, and is expressly prohibited from modifying the information or creating derivative works without the express

written consent of Alcatel-Lucent.

All rights reserved Alcatel-Lucent @@YEAR

4. Disclaimer

In no event will Alcatel-Lucent be liable for any direct, indirect, special, incidental or consequential damages, including

lost profits, lost business or lost data, resulting from the use of or reliance upon the information, whether or not Alcatel-

Lucent has been advised of the possibility of such damages.

Mention of non-Alcatel-Lucent products or services is for information purposes only and constitutes neither an

endorsement, nor a recommendation.

This course is intended to train the student about the overall look, feel, and use of Alcatel-Lucent products. The

information contained herein is representational only. In the interest of file size, simplicity, and compatibility and, in some

cases, due to contractual limitations, certain compromises have been made and therefore some features are not entirely

accurate.

Please refer to technical practices supplied by Alcatel-Lucent for current information concerning Alcatel-Lucent equipment

and its operation, or contact your nearest Alcatel-Lucent representative for more information.

The Alcatel-Lucent products described or used herein are presented for demonstration and training purposes only. Alcatel-Lucent disclaims any warranties in connection with the products as used and described in the courses or the related

documentation, whether express, implied, or statutory. Alcatel-Lucent specifically disclaims all implied warranties,

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5. Governing Law

The products, documentation and information contained herein, as well as these Terms of Use and Legal Notices are

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Terms of Use and Legal Notices shall remain in full force and effect.


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4

Blank Page




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5

Course Outline

About This CourseCourse outline

Technical support

Course objectives

1. Topic/Section is Positioned HereXxx

Xxx

Xxx

2. Topic/Section is Positioned Here






1. BSS B10-B11 Telecom Evolutions

1. Support of Paging Coordination

2. Repeated ACCH

3. NACC for Inter BSS and Inter RAT

4. Tandem Free Operation with AMR-NB

5. Support of A5.3 Ciphering

6. Synchronized Radio Network

7. TRX Dynamic Power Saving

8. Abbreviations


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6

Course Outline [cont.]




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7

Course Objectives


Welcome to BSS B10-B11 Telecom Evolutions

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

By the end of the course, participants will be able to describe the new telecom B11

features and their telecom impacts.


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8

Course Objectives [cont.]




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9

About this Student Guide

Switch to notes view!Conventions used in this guide

Where you can get further information

If you want further information you can refer to the following:

Technical Practices for the specific product

Technical support page on the Alcatel website: http://www.alcatel-lucent.com

Note

Provides you with additional information about the topic being discussed.Although this information is not required knowledge, you might find it useful

or interesting.

Technical Reference(1) 24.348.98 Points you to the exact section of Alcatel-Lucent Technical

Practices where you can find more information on the topic being discussed.

WarningAlerts you to instances where non-compliance could result in equipment

damage or personal injury.


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10

About this Student Guide [cont.]




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11

Self-assessment of Objectives

At the end of each section you will be asked to fill this questionnaire

Please, return this sheet to the trainer at the end of the training


Instructional objectivesYes (orglobally

yes)

No (orglobally

no)Comments

1 To be able to XXX

2

Contract number :

Course title :

Client (Company, Center) :

Language : Dates from : to :Number of trainees : Location :

Surname, First name :

Did you meet the following objectives ?

Tick the corresponding box

Please, return this sheet to the trainer at the end of the training


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12

Self-assessment of Objectives [cont.]


Instructional objectivesYes (orGlobally

yes)

No (orglobally

no)Comments

Thank you for your answers to this questionnaire

Other comments


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Section 1 Module 1 Page 1


3JK11693AAAAWBZZA Issue 1.0

Do not delete this graphic elements in here:


Module 1Support of Paging Coordination


Section 1BSS B10-B11 Telecom Evolutions

Base Station SubsystemBSS B10-B11 Telecom Evolutions

TMO18090 Issue 1.0


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Base Station Subsystem BSS B10-B11 Telecom EvolutionsBSS B10-B11 Telecom Evolutions Support of Paging Coordination

1 1 2

Blank Page


First editionEljaafari, Mohamed2009-03-3001

RemarksAuthorDateEdition

Document History


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1 1 3

Module Objectives

Upon completion of this module, you should be able to:

Describe the purpose of the "Support of Paging Coordination in the BSS"

feature and its Telecom and O&M impacts


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1 1 4

Module Objectives [cont.]



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1 1 5

Table of Contents

Switch to notes view! Page

1 What Is the Purpose of this Feature? 71.1 Paging Coordination Principle in B10 81.2 Paging Coordination Principle in B11 11

2 How Does It Work? 122.1 Overall Description 13

3 What Are the Telecom Impacts? 173.1 CS Paging Requests Processing 18

4 What Are the O&M Impacts? 204.1 Feature Activation 214.2 Performance Management 22


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1 1 6

Table of Contents [cont.]




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1 1 7

1 What Is the Purpose of this Feature?


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1 1 8


1.1 Paging Coordination Principle in B10

Do you remember the CS paging coordination in B10?Select t he corr ect st at ement s.

In NMO-II or NMO-III, the MS cannot receive CS paging while in PacketTransfer Mode

The Gs interface is a pre-requisite to fully support the DTM feature

If the network operates in NMO-I, there is no Gs interface between the MSCand the SGSN

In case of NMO-I, the paging coordination is done by the core network(between the MSC and the SGSN)

Paging coordination is an Alcatel-Lucent specific feature


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1 1 9


1.1 Paging Coordination Principle in B10 [cont.]

Without paging coordination, CS Paging messages are always broadcastthrough the CCCH/PCH channel, even if the MS is in PTM mode.

MFS SGSNPDCHs

CSpaging

CSpaging

PCH

PACCH

CSpaging

Serving cell

BSC MSC

WithoutGs interface

IN B10 We have 3


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1 1 10


1.1 Paging Coordination Principle in B10 [cont.]

With paging coordination in the SGSN, CS paging messages for GPRS-attached MS are conveyed from the MSC to the SGSN through the Gsinterface. It corresponds to the Network Mode of Operation I (NMO-I).

Serving cell

MFS SGSN

BSC MSC

Gs

TCHDedicated

mode

PACCH

CSpaging

CSpaging

CSpaging

CS

paging

Paging coordinationin the SGSN usingthe Gs interface


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1 1 11


1.2 Paging Coordination Principle in B11

The support of paging coordination improves CS paging performance, asit allows to send CS paging messages through the PACCH.

In B11, this procedure can be fully performed in the BSS.

Serving cell

MFS

BSC MSC

WithoutGs interface

SGSN

PCH

GSL

Dedicatedmode

PACCH

CSpaging

CSpaging

CSpaging

CSpaging

CSpaging

CSpaging

Paging coordinationin the BSSTCH

There are two ways to support paging coordination:

Prior to B11, paging coordination is performed in the SGSN. In such a case, CS paging messages for GPRS-attached MS are conveyed from the MSC to the SGSN through the Gs interface, which allows the SGSN to

perform the paging coordination. This corresponds to the Network Mode of Operation I.

In B11, paging coordination is performed in the BSS. If no Gs interface is available then CS pagingcoordination has to be fully performed in the BSS.


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1 1 12

2 How Does It Work?


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1 1 13

2 How Does It Work?

2.1 Overall Description

With CS paging coordination in the BSS, the BSC has to forward to theMFS CS Paging requests received from the MSC.

Knowing that the BSC is aware of neither the MS location nor the MS

mode (PTM or not), and the fact that we have to be very careful withthe GSL load, can you guess which kind of information shall be sent tothe MFS?

Select t he corr ect answer.

Indication about the Paging Area

The cell the MS camps on

List of all cells managed by the BSC

MS Location Area

MS IMSI

PTM/non-PTM mode

Nothing


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1 1 14

2 How Does It Work?

2.1 Overall Description [cont.]

The BSC forwards to the MFS CS Paging requests received from the MSC in orderto allow the MFS to send the paging requests on the PACCH channel.

The BSC also broadcasts all CS paging requests to the MS through the PCHchannel.

Serving cell

MFS

BSC MSC

GSL

SGSN

WithoutGs interface

PCH CSpaging

CSpaging

CSpaging

CSpaging

Paging coordination in the BSS

MS in PIMMFS discards the Paging Request

IMSI

CS paging coordination in the BSS is performed in 3 steps:

1. CS paging requests are received from the MSC.

2. The BSC forwards CS paging requests to the MFS via the GSL (using BSCGP) after filtering. In any case the

BSC also broadcasts all CS paging requests to the MS through the PCH channel (for all cells corresponding tothe Paging Area and managed by the BSC).

3. On receipt of the CS paging requests sent by the BSC and when applicable (i.e. for MS in PTM mode), the

MFS sends these CS paging requests to the MS through the PACCH channel (for the cell the MS camps on).

Management of the IMSI by the MFS

When CS paging coordination is performed in the BSS, no Paging Area is provided within CS Paging Requestsforwarded by the BSC but only the IMSI. Therefore the MFS has to build and maintain a set of IMSI vs MSContext relationships for all MS in PTM mode.


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1 1 15

2 How Does It Work?


The BSC forwards to the MFS CS Paging requests received from the MSC in orderto allow the MFS to send the paging requests on the PACCH channel.

The BSC also broadcasts all CS paging requests to the MS through the PCHchannel.

Serving cell

MFS

BSC MSC

WithoutGs interface

SGSN

PCHGSL

Dedicatedmode

PACCH

CSpaging

CSpaging

CSpaging

CSpaging

CSpaging

CSpaging

MS in PTM modewill be paged faster on the PACCH

than on the PCH

TCH Paging coordinationin the BSS

CS paging coordination in the BSS is performed in 3 steps:

1. CS paging requests are received from the MSC.

2. The BSC forwards CS paging requests to the MFS via the GSL (using BSCGP) after filtering. In any case the

BSC also broadcasts all CS paging requests to the MS through the PCH channel (for all cells corresponding tothe Paging Area and managed by the BSC).

3. On receipt of the CS paging requests sent by the BSC and when applicable (i.e. for MS in PTM mode), the

MFS sends these CS paging requests to the MS through the PACCH channel (for the cell the MS camps on).

Management of the IMSI by the MFS

When CS paging coordination is performed in the BSS, no Paging Area is provided within CS Paging Requestsforwarded by the BSC but only the IMSI. Therefore the MFS has to build and maintain a set of IMSI vs MSContext relationships for all MS in PTM mode.


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1 1 16

2 How Does It Work?


Are the following statements about the CS Paging coodination in theBSS true or false?Match t he corr ect answers.

The feature cannot be useful independently from the DTM feature

Paging Coordination functions were defined first in Release 1999,as part of the DTM feature

CS paging requests for non-GPRS attached MS or MS not inPTM mode are also conveyed on the GSL

The MFS is responsible for checking if the MS is in PTM modeand if so, to find the cell the MS camps on which is clearly

something new for the MFS

The two ways to perform Paging Coordination (in BSS / inSGSN) can be handled simultaneously for a given BSS

True

False

he need to know IMSI


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1 1 17

3 What Are the Telecom Impacts?


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1 1 18


3.1 CS Paging Requests Processing

T_SEND_MULTIPLE_PAGING_COMMAND

NB_MAX_MULTIPLE_PAGING_COMMAND PAGING

commands buffered(or T_SEND_MULTIPLE_PAGING_COMMAND timer elapses)

For each IMSI check the availability of the MS ContextIF PTM mode IMSI found

BTS BSC MFS MSC

Start T3113 for MS1

Start T3113 for MS5

Multiple pagingcommand scenario

1

2

34

5

MULTIPLE PAGINGCOMMAND (MSn, pgrk)

PAGING (MS5)

PAGINGCOORDINATION_REQUEST(IMSI1,IMSI2, )

PACKET PAGINGREQUEST (IMSI) on

PACCH

PAGING (MS1)

A new message PAGING_COORDINATION_REQis introduced in theBSCGP to forward CS paging to the MFS.Fi l l i n the blank boxes on the lef t wi t h the appropr i at e number t o re-bui ld t he

scenar i o in the r ight order.

PAGING_COORDINATION_REQ:

A new message is introduced in the BSCGP to forward CS paging to the MFS. The same new message is usedfor both Pagi ng commandand Mult ipl e Paging commandscenarios.

3

2

4

5

1

PCHGSL

PACCH


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1 1 19


3.1 CS Paging Requests Processing [cont.]

The MFS has to maintain a set of "IMSI vs MS Context" relationships:

For an MS which leaves the PTM mode, the corresponding "IMSI vs MSContext" relationship has to be removed from the set.

For an MS which enters the PTM mode, its IMSI has to be retrieved.

In your opinion, how must the IMSI be retrieved?Select t he corr ect answers.

For a DL TBF, pick the IMSI from a DL LLC PDU

The IMSI is retrieved only during GPRS Attach

For a UL TBF, perform an RA Capacity Update procedure

For a UL TBF, perform the two-phase access procedure


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1 1 20

4 What Are the O&M Impacts?


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1 1 21


4.1 Feature Activation

New Parameter

The "Support of Paging Coordination in the BSS" feature is optional. Itshall be activated at BSS level, via the OMC-R:

BSS_PAGING_COORDINATION

BSS_PAGING_COORDINATION:

Enables CS Paging Coordination to be managed in the BSS for MS in Packet Transfer Mode.

The default value is "Disabled".

Recommended rules:

If BSS_PAGING_COORDINATION (BSC)/(MFS) is set to "Enabled", it is highly recommended to setEN_RA_CAP_UPDATE to "Enabled" for all cells of the corresponding BSS.

If DTM is Enabled for at least one cell within a given BSS, it is highly recommended to activate CS PagingCoordination for this BSS, either through the Gs Interface (network_operation_mode = "NMO I") or by setting

BSS_PAGING_COORDINATION (BSC)/(MFS) to "Enabled" (network_operation_mode "NMO I").

Note

The activation of DTM is NOT a prerequisite to activate the "Support of paging coordination in the BSS"feature. This feature can be used to simply improve CS paging performance for MS in PTM mode without

having mandatorily DTM in mind.

As Network_Operation_Mode is defined on a per BSS basis, the two ways to perform Paging Coordination

cannot be handled simultaneously for a given BSS. On the other hand, nothing prevents to use both atNetwork level.


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1 1 22


4.2 Performance Management

PM Counters

No new PM counters are needed, as the extra GSL load brought by thefeature can be monitored using 2 PM counters:

NB_PAGING_COMMANDS_RECEIVED_ABIS NB_PS_PAGING_REQ_GPU

NB_PAGING_COMMANDS_RECEIVED_ABIS (MC925g):

This counter accumulated by the BTS and reported by the BSC counts on a per cell basis the CS + PSPAGING commands sent on Abis and broadcast on PCH (in case of Multiple Paging, all embedded commandsare counted).

NB_PS_PAGING_REQ_GPU (P391a):

This counter is managed by the MFS and counts on a per GPU basis the PS Paging Requests received through

the Gb interface.


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1 1 23

Module Summary

If no Gs interface is available then CS paging coordination has to befully performed in the BSS.

With paging coordination in the BSS, the BSC sends all receivedpaging requests from the MSC both to the PCH and to the MFS.

Paging coordination is mandatory to fully support the DTM feature.

This new feature can be useful independently from the DTM.

The two ways to perform paging coordination cannot be handled

simultaneously for a given BSS.

The feature activation is configured from the OMC-R via theBSS_PAGING_COORDINATION parameter.


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1 1 24

Self-assessment on the Objectives

Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module

The form can be found in the first partof this course documentation


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1 1 25

End of ModuleSupport of Paging Coordination


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Module 2Repeated ACCH




TMO18090 Issue 1.0


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Base Station Subsystem BSS B10-B11 Telecom EvolutionsBSS B10-B11 Telecom Evolutions Repeated ACCH

1 2 2

Blank Page




Document History


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1 2 3

Module Objectives


Describe the purpose of the "Repeated DL FACCH and Repeated UL & DL

SACCH" features and their Telecom and O&M impacts


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1 2 5

Table of Contents


1 What Is the Purpose of this Feature? 71.1 FACCH and SACCH 81.2 Voice and Signaling Coverage without AMR in B10 9

1.3 Improved Voice Coverage with AMR in B10 101.4 Improved Coverage in B11 11

2 How Does It Work? 122.1 Repeated DL FACCH 132.2 Dynamic Activation of RDFACCH 152.3 Repeated DL SACCH 172.4 Repeated UL SACCH 192.5 Dynamic Activation of RSACCH 21

3 What Are the Telecom Impacts? 243.1 RUSACCH and RLS 25

4 What Are the O&M Impacts? 274.1 RDFACCH Enabling 284.2 RSACCH Enabling 29

4.3 Performance Management 30


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1 2 8


1.1 FACCH and SACCH

Do you remember FACCH and SACCH?Select t he corr esponding signal ing channel.

The FACCH SACCH is associated with a TCH, and is required to support the high-speed signaling needed during

call establishment and HO management.

The occurrence of the FACCH SACCH is not fixed in the multiframe, as it is for the FACCH SACCH..Insted, the FACCH SACCH occurs on a TDMA frame that is reserved for a TCH.

An FR TCH uses one TS per TDMA frame, for each frame of the multiframe, except for the frames 12 and 25. The TDMA

frame 12 is used to carry the FACCH SACCH and the TDMA frame 25 is an idle frame.

The FACCH SACCH multiframe/block is composed of four FACCH SACCH frames/bursts; thus theFACCH SACCH period is equal to 480ms.

The FACCH SACCH is used mainly for the transmission of the radio measurement data.FACCH SACCH is also used for SMS transfer during a call.

The multiplexing of TCH and FACCH SACCH is possible by means of the frame stealing. This means that a speechframe carried over a TCH can be replaced by an FACCH SACCH frame.

The BTS sends cell-specific information (periodically SYS_INFO 5, 5bis, 5ter, 6) to the MS using FACCH SACCH.


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1 2 9


1.2 Voice and Signaling Coverage without AMR in B10

When AMR speech codecs were introduced, the same Associated ControlChannels (ACCHs) as those used for traditional TCH/FR and TCH/EFRwere re-used. The consequence is that, in poor radio conditions, the

more protected AMR speech codecs have now better performance (interms of error rate) than the associated control channels. This resultsin an imbalance between voice and signaling.

Voice andsignaling coverage

without AMR

Z

Z Z

Call Drop

BTS


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1 2 10


1.3 Improved Voice Coverage with AMR in B10

When AMR speech codecs were introduced, the same Associated ControlChannels (ACCHs) as those used for traditional TCH/FR and TCH/EFRwere re-used. The consequence is that, in poor radio conditions, the

more protected AMR speech codecs have now better performance (interms of error rate) than the associated control channels. This resultsin an imbalance between voice and signaling.

BTS

Call Drop

Improved voice coveragewith AMR

Z

Z Z

Signaling channelsdesigned at the

beginning of GSMless robust than

AMR codecRisk of call drop

while voice qualityis still OK

at cell border

AMR codecs are more resistant than the signaling channel (SACCH).

AMR calls can be stopped because of RLT expiry due to persistent bad SACCH quality (while AMR codec stillperforming well), in particular in FR usage.

In B10, a shorter-term solution to fix this issue was the Differentiated Radio Link Timeout for AMR callsfeature. It is desirable to use higher RLT values for AMR calls than for Legacy Codecs.

A long-term solution is to strengthen SACCH. This is introduced in B11 with the new Repeated DL FACCHand Repeated UL & DL SACCH feature.


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1 2 11


1.4 Improved Coverage in B11

In B11, the Repeated DL FACCH and Repeated UL & DL SACCHfeatures improve the robustness of signaling.

Repeated UL & DL SACCH (RSACCH): Extended Coverage & reduction of call

drops. Repeated DL FACCH (RDFACCH): Improves handover reliability of AMR calls.

BTS

Improved coverage with RSACCH and RDFACCH


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1 2 12

2 How Does It Work?


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1 2 13

2 How Does It Work?

2.1 Repeated DL FACCH

TCHframe

Hf

rame

F

ACCHn+2,2

BTSLAPDm

Rel-6MS

Outcome ofthe decoding

process

AMRCall

TCHframe

F

ACCHn+2,1

TCHframe

TCHframe

F

ACCHn+1,2

TCHframe

F

ACCHn+1,1

TCHframe

TCHframe

TCHframe

FACCHn,2

TCHframe

FACCHn,1

TCHframe

Soft combining

Downlink

When the RDFACCH feature is activated for a given MS, each DL FACCH frameis sent twice with exactly the same contents. The MS shall, when receiving aDL FACCH block, always attempt to decode it without combining with anypreviously received FACCH block. If the current FACCH block is unsuccessfully

decoded and there was an unsuccessfully decoded FACCH block, a newdecoding using these 2 FACCH blocks shall be performed (soft combining).RDFACCH is mandatory for Rel-6 mobile stations.

Without the RDFACCH, the FACCH blocks are decoded without taking into account the history of the

previously sent FACCH blocks.

The main goal of the repeated downlink FACCH feature is to increase the transmission success rate of the

single-block handover commands.

If the current FACCH block is successfully decoded and an identical FACCH block was previously received

(successfully decoded and spaced in time from the current FACCH block), the MS shall not send the LAPDm

frame of the current FACCH block to the LAPDm entity.

If the current FACCH block is successfully decoded and there was no such previously received identicalFACCH block, the LAPDm frame of the current FACCH block is sent to the LAPDm entity.

If the current FACCH block is unsuccessfully decoded and there was an unsuccessfully decoded FACCHblock spaced in time from the current FACCH block, a new decoding using the information from both these

FACCH blocks shall be performed. If this decoding is successful, the LAPDm frame produced by the newdecoding is sent to the LAPDm entity.


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1 2 14

2 How Does It Work?

2.1 Repeated DL FACCH [cont.]

Have you understood the RDFACCH mechanism?Select t he corr ect st at ement s.

Prior to B11, FACCH blocks are decoded without taking into account the history of thepreviously sent FACCH blocks

The MS shall, when receiving a DL FACCH block, always attempt to decode it using the softcombining procedure

The MS performs soft combining only when the two received FACCH blocks are unsuccessfullydecoded

In case of TCH/FR, the transmission of the repeated FACCH is done by leaving one TCH framebetween the two LAPDm frames

The RDFACCH can also be used in case of TCH/HR

The operations of RDFACCH is not transparent to upper layers

Even if RDFACCH could have brought a gain for non-AMR calls, it applies only to AMR calls


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1 2 15

2 How Does It Work?

2.2 Dynamic Activation of RDFACCH

AMR Codec-Based Activation

RDFACCH is decided dynamically in the BTS if the DL codec requested(CMR value) is inferior or equal to a given codec threshold (e.g.

5.9kbps). The codec threshold is an OMC-R parameter for this cell.

Repe

ated

FACC

Hn

Codec threshold

5.15

5.9

7.95

10.2

BTS

RDFACCH

active

FACC

Hn

Dynamic activationas long as the CMR value

is inferior or equal to the codec threshold

TCH


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1 2 16

2 How Does It Work?

2.2 Dynamic Activation of RDFACCH [cont.]

Have you understood the dynamic activation of RDFACCH?Click on each but t on in the r i ght order t o display t he st eps of t his scenar i o.

FACCH frame n

If new codec inferior tocodec threshold

RDFACCH frame n

TCH frame

CMR (new codec)

C/I evaluation & thresholdcomparison

RDFACCH Activation

1

2 3

4

5

6

7

MS Rel-6 BTS

1

2

5

3

7

6

2

1

4


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1 2 17

2 How Does It Work?

2.3 Repeated DL SACCH

SACCHn+4

CCH

n+3

BTSLAPDm

Rel-6 MS

AMRCall

Downlink

Outcome of

the decodingprocess

Uplink

SACCHn+2,1

SACCH

SACCHn+1,2

SACCHn+1,1

SACCHn,1

SACCH

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

480ms480ms 480ms480ms 480ms

Softcombining

Softcombining

SACCHn+2,2

SACCH

SRR=1

Softcombining

SACCH

SRR=1

SACCH

SRR=1

The RDSACCH mechanism means that the BSS may send a DL SACCH frame twice with exactly thesame contents to improve the DL SACCH performance thanks to combining in the MS. When receiving aDL SACCH block, the MS shall first attempt to decode it without combining. If this decoding fails, thensoft combining using the previous SACCH block shall be performed. RDSACCH and RUSACCH aremandatory for Rel-6 mobile stations.

SACCH Repetition Request (SRR)

If a DL SACCH block is incorrectly decoded (prior to combining with any previously received SACCHblock), and the next UL SACCH block is not a repetition as per the Repeated SACCH procedure, then the MS

shall set the SRRin the next UL SACCH block to "Repeated SACCH required" (see 3GPP TS 44.004).

If a DL SACCH block is correctly decoded (prior to combining with any previously received SACCH block),and the next UL SACCH block is not a repetition as per the Repeated SACCH procedure, the MS shall set theSRRin the next UL SACCH block to "Repeated SACCH not required".

On BSS side, if a transmitted downlink SACCH block contains a SAPI 0 frame and is not already a repetition,then it is a repetition candidate.

?SRR=1


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2 How Does It Work?

2.3 Repeated DL SACCH [cont.]

Have you understood the RDSACCH mechanism?Select t he corr ect st at ement s.

When the MS cannot decode correctly (before combining) a DL SACCH, it requests for repetitionby setting the SRR bit.

On BTS/LAPDm side, any DL SACCH block can be repeated.

RDSACCH involves only 2 layers: the LAPDm in the BTS on the one hand and the physical layer inthe MS on the other hand.

When the RDSACCH feature is activated, any DL SACCH frame is sent twice.

If the last DL SACCH frame can not be decoded, the MS tries to soft combine it with the previousframe.

RSACCH is mandatory for Rel-6 MSs, furthermore it cannot be applied to legacy MSs, contrary toRDFACCH.


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2 How Does It Work?

2.4 Repeated UL SACCH

The RUSACCH mechanism means that an MS shall send upon BSS order a UL SACCH frametwice with exactly the same contents to improve the UL SACCH performance thanks tocombining in the BTS.

BTSLAPDm

AMRCall

Downlink

Outcome ofthe decoding

process

Uplink

SACCHm+4,1

SACCHn+3,2

SACCHn+3,1

SR0=1

SACCHm+3,2

SACCHm+3,1

SACCHn+2,1

SACCHm+2,1

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

TCHs

480ms480ms 480ms480ms 480ms

SACCHn+4

Rel-6 MS

Softcombining

Softcombining

SACCHm+4,2

SACCHn+4,1

SR0=1

SACCH

n+4,2

SR0=1

Softcombining

SACCH Repetition Order (SRO)

On MS side:

If a transmitted uplink SACCH block contains a SAPI 0 frame and is not already a repetition, then it is a

repetition candidate.

If an SACCH block is a repetition candidate and if the last correctly received SACCH Repetition Orderwas set to SRO, then the MS shall repeat this SACCH block at the next SACCH block period.

On BSS side:

When receiving a UL SACCH block, the BSS may first attempt to decode it without combining with any

previously received SACCH block. If this decoding fails, then a new decoding using the information fromthis SACCH block and from the SACCH block received at the previous SACCH block period, may beperformed.


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2 How Does It Work?

2.4 Repeated UL SACCH [cont.]

Have you understood the RUSACCH mechanism?Select t he corr ect st at ement s.

A UL SACCH block containing a SAPI 0 frame, which is not already repeated, is a repetition candidate.

A UL SACCH block containing an SMS, if it is not already a repetition, then it is also a repetitioncandidate.

The SRO bit shall be set in the SACCH DL frames in order to tell the MS to repeat the UL SACCH frames.

When the RUSACCH feature is activated, same mechanism as for the RDFACCH, each UL SACCH frame issent twice systematically.

When the SACCH block n has to be repeated, its repetition is performed at SACCH block period n+1.

The BTS does not know if a UL SACCH frame is a repetition or not.

The BTS should always try to perform combining between successive SACCH blocks, even if RUSACCH isnot currently activated.


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1 2 21

2 How Does It Work?

2.5 Dynamic Activation of RSACCH

The RDSACCH is activated if at least 3 SRR bits set to 1 have beenreceived in a window whose size is equal to 10 successive UL SACCHperiods. Inversely, the RDSACCH is deactivated if less than 3 SRR bits

set to 1 have been received in the decision window. A similar algorithmis used for the RUSACCH. The state of RSACCH activation shall beupdated in every SACCH period.

In the example below, is the RDSACCH activated or not?Select t he corr ect answer f or each SACCH peri od.

1715131197531 42 6 8 10 12 14 16SACCH Period

100010110 11 1 0 0 0 0 1SRR Value

3/102/104/106/106/95/74/52/30/1 3/41/2 5/6 5/8 6/10 5/10 3/10 2/10SRR Sum

RDSACCHactivated?

Yes

No

Activation of RDSACCH

The RDSACCH is activated if at least REP_DL_SACCH_THRES SRR bits set to 1 have been received in awindow whose size is equal to REP_DL_SACCH_WS successive UL SACCH periods. Inversely, the RDSACCH isdeactivated if less than 3 SRRbits set to 1 have been received in the decision window.

Activation of RUSACCH

The RUSACCH is activated if at least REP_UL_SACCH_THRES UL SACCH messages have not been correctlyreceived before combining in a window whose size is equal to REP_UL_SACCH_WS successive UL SACCHperiods. Inversely, the RUSACCH is deactivated if less than REP_UL_SACCH_THRES UL legacy SACCHmessages have not been correctly received before combining in the window. This means the BTS shallalways try to first decode the SACCH before any combining.

Note

REP_DL_SACCH_THRES and REP_DL_SACCH_WS are constants in the DLS defined at BSC level. They arerespectively set by default to 3 and 10.

REP_UL_SACCH_THRES and REP_UL_SACCH_WS are constants in the DLS defined at BSC level. They arerespectively set by default to 3 and 10.


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2 How Does It Work?

2.5 Dynamic Activation of RSACCH [cont.]

The RDSACCH is also triggered when the UL RLT counter is inferior orequal to the value of RADIOLINK_REP_DL_SACCH. This avoids blockingscenarios and enables to react in case of rapid UL field drops (i.e. in

case the SRRis not received anymore due to bad UL quality).

BadUL SACCHRel-6 MS

BTS

RADIOLINK_RECOVERY_THRES

RLS Counter

10

09

RADIOLINK_REP_DL_SACCH

RADIOLINK_TIMEOUT_BS

RDSACCHactivation

RADIOLINK_REP_DL_SACCH is set by default to 10 (i.e. equal to RADIOLINK_RECOVERY_THRES (=N_BSTXPWR_M) - 3) to give time to the BSS to set the power output of the BTS and of the MS to itsmaximum value (recovery mechanism).


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1 2 23

Exercise

Have you understood the RUSACCH, RDFACCH and RDSACCH mechanisms?Match each i t em on the lef t wi t h the corr esponding f eat ures.

AMR Codec-based dynamic activation

Dynamically activated using SRR or RLT procedures

Mandatory for Rel-6 MS

Each frame is sent twice

A frame may be sent twice

It can be applied to legacy (pre-Rel-6) MS

New SACCH Repet i t i on Or der (SRO)field

RDFACCH

RUSACCH

RDSACCH


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1 2 25


3.1 RUSACCH and RLS

The introduction of RUSACCH has an impact on the receiving principleof SACCH blocks and on the Radio Link Supervision (RLS).

1817


RLS Counter

1615

1413

121110

09



BadUL SACCH

Outcome ofthe first decoding

+Outcome of

the second decoding

=Soft combining

BTS

Rel-6MS

SACCH Block Receiving Procedure and Radio Link Supervision

In B11, with the possibility of a repeated UL SACCH, the following principle shall be used:

When an SACCH block is received, there's a first decoding attempt without combining:

If the decoding is performed, then the RLT counter is incremented by 2.

If the decoding is not performed, then a second decoding is attempted by combining with the previous

SACCH block:

If the second decoding is successful, then the RLT counter is incremented by 2.

If the second decoding failed, then the RLT counter is decremented by 1.


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3.1 RUSACCH and RLS [cont.]

The introduction of RUSACCH has an impact on the receiving principleof SACCH blocks and on the Radio Link Supervision (RLS).

Outcome ofthe first decoding

BTS

Rel-6MS

+Outcome of

the second decoding

=Soft combining


RLS Counter

171615

1413

121110

09



BadUL SACCH

SACCH Block Receiving Procedure and Radio Link Supervision

In B11, with the possibility of a repeated UL SACCH, the following principle shall be used:

When an SACCH block is received, there's a first decoding attempt without combining:

If the decoding is performed, then the RLT counter is incremented by 2.

If the decoding is not performed, then a second decoding is attempted by combining with the previous

SACCH block:

If the second decoding is successful, then the RLT counter is incremented by 2.

If the second decoding failed, then the RLT counter is decremented by 1.


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4.1 RDFACCH Enabling

New Parameters

The RDFACCH feature is optional. It can be enabled at cell level. EN_REP_DL_FACCH

REP_DL_FACCH_LEGACY_SUPPORT REP_DL_FACCH_THRES_AMR_FR

REP_DL_FACCH_THRES_AMR_HR

REP_DL_FACCH_THRES_AMR_WB

EN_REP_DL_FACCH

Definition: Enables repeated downlink FACCH for AMR calls.

Instance: cell, changeable.

Range/default value: Three levels: 0: Repeated DL FACCH not enabled (default), 1: Repeated DL FACCH enabled for LAPDm

command frames,2: Repeated DL FACCH enabled for LAPDm command frames, and also for LAPDm response frames (valid only for

the MS having indicated the support of the feature by Repeated ACCH Capability bit=1).

REP_DL_FACCH_LEGACY_SUPPORT

Definition: Legacy support for Repeated Downlink FACCH for AMR calls.

Remarks: This parameter is relevant only if Repeated Downlink FACCH is enabled (EN_REP_DL_FACCH parameter). This parameter

concerns only the LAPDm command frames.

Instance: cell , changeable.

Range/default value: 0: Repeated DL FACCH enabled only for the AMR MSs having indicated the support of the feature by

Repeated ACCH Capability bit=1 (default), 1: Repeated DL FACCH enabled for all AMR MSs.

REP_DL_FACCH_THRES_AMR_FR

Definition: Repeated DL FACCH activation threshold for AMR FR. Dynamic activation is done as long as CMR is inferior or equal to the

threshold value.

Instance: cell, changeable

Range/default: 0=off, 1=4.75kbps, 2=5.15kbps, 3=5.9kbps (default), 4=6.7kbps, 5=7.4kbps, 6=7.95kbps, 7=10.2kbps, 8=12.2kbps

REP_DL_FACCH_THRES_AMR_HR

Definition: Repeated DL FACCH activation threshold for AMR HR. Dynamic activation is done as long as CMR is inferior or equal to the

threshold value.


Range/default: 0=off, 1=4.75kbps, 2=5.15kbps, 3=5.9kbps (default), 4=6.7kbps, 5=7.4kbps

REP_DL_FACCH_THRES_AMR_WB

Definition: Repeated DL FACCH activation threshold for AMR WB. Dynamic activation is done as long as CMR is inferior or equal to the

threshold value.


Range/default: 0=off, 1=6.60kbps (default), 2=8.85kbps, 3=12.65kbps


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4.2 RSACCH Enabling

New Parameters

The RSACCH feature is optional. It can be enabled at cell level. EN_REP_SACCH

RADIOLINK_REP_DL_SACCH L_RXQUAL_UL_P_AMR_RXACCH

L_RXQUAL_DL_P_AMR_RXACCH

EN_REP_SACCH

Definition: Enables repeated SACCH for SAPI 0 frames in case of AMR calls (for MSs having indicated thesupport of the feature).


Range/default value: Flag 0: Repeated SACCH not enabled (default), 1: Repeated SACCH enabled.


Definition: Counter threshold of UL RTL counter to activate Repeated DL SACCH.


Range: 1 to 128 (default: 10)

L_RXQUAL_UL_P_AMR_RXACCH

Definition: Lower uplink quality threshold for power control for AMR calls with activated Repeated DL

FACCH and Repeated SACCH.


Range: 0 to 7 (default: 3) - (use the value of L_RXQUAL_UL_P for migration).

L_RXQUAL_DL_P_AMR_RXACCH

Definition: Lower downlink quality threshold for power control for AMR calls with activated Repeated DL

FACCH and Repeated SACCH. Instance: cell, changeable.

Range: 0 to 7 (default: 3) - (use the value of L_RXQUAL_DL_P for migration).


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4.3 Performance Management

New Counters NB_MS_REPEATED_ACCH_CAPABLE

NB_CALLS_RFACCH_ACTIVATED

NB_CALLS_RSACCH_ACTIVATED NB_AMR_TCH_DROP_RLF_TRX

NB_AMR_TCH_DROP_RLF_TRX_RSACCH

NB_MS_REPEATED_ACCH_CAPABLE (MC990)

Definition: Number of calls for which the mobile stations support the repeated ACCH capability.

Trigger condition: Each time the BSC gets for a call the indication of the corresponding MS Repeated ACCH Capability in the classmark

3 IE at the time of Channel Activation or Mode modify messages sending, this counter is incremented by one.

NB_CALLS_RFACCH_ACTIVATED (MC991)

Definition: Number of calls for which repeated DL FACCH is allowed by the BSC.

Trigger condition: Each time the BSC sends a Channel Activation or a Mode Modify to a BTS indicating that RDFACCH is activated for

LAPDm command frames and/or LAPDm response frames, then this counter is incremented by 1. For Mode Modify trigger, only the

cases where RDFACCH was not activated in the Channel Activation message previously sent by the BSC are counted.

NB_CALLS_RSACCH_ACTIVATED (MC992)

Definition: Number of calls for which repeated SACCH (DL or UL) is allowed by the BSC.

Trigger condition: Each time the BSC sends a Channel Activation or a Mode Modify to a BTS indicating that RSACCH (UL and/or DL) is

activated, then this counter is incremented by 1. For Mode Modify trigger, only the cases where RSACCH was not activated in the

Channel Activation message previously sent by the BSC are counted.

NB_AMR_TCH_DROP_RLF_TRX (MC993)

Number of AMR TCHs (NB or WB AMR) for which Repeated SACCH is not activated, dropped in TCH established phase due to radio link

failure (radio link timeout or Lapdm timer expiry), per TRX. For TCH using AMR codecs (NB or WB) but for which the feature Repeated

SACCH is not activated by the BSC:

1)Whenever a 48.058 CONNECTION FAILURE INDICATION message with a cause value of "radio link failure" is received on Abis interface

for a TCH channel (after successful seizure).

2) Whenever a 48.058 ERROR INDICATION message is received on Abis interface and leads to a loss of call.

NB_AMR_TCH_DROP_RLF_TRX_RSACCH (MC994)

Number of AMR TCHq (NB or WB AMR) for which Repeated SACCH is activated, dropped in TCH established phase due to radio link

failure (radio link timeout or Lapdm timer expiry), per TRX. This counter takes into account TCH in traffic. For TCH using AMR codecs

(NB or WB) but for which the feature Repeated SACCH is activated by the BSC:

1)Whenever a 48.058 CONNECTION FAILURE INDICATION message with a cause value of "radio link failure" is received on Abis interface

for a TCH channel (after successful seizure).

2)Whenever a 48.058 ERROR INDICATION message is received on Abis interface and leads to a loss of call.

NPO checkings with this above parametrs in indicaters.


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1 2 31

Module Summary

The Repeated DL FACCH (RDFACCH) and Repeated UL & DL SACCH(RSACCH) features improve the robustness of signaling.

The RDFACCH mechanism means that each DL FACCH frame is senttwice.

The RUSACCH mechanism means that an MS shall send upon BSS ordera UL SACCH frame twice.

The RDSACCH mechanism means that the BSS may send a DL SACCHframe twice.

The dynamic activation ofRDFACCH is AMR Codec based.

SRR=1

SRO=1

MAY


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1 2 32

Module Summary [cont.]

RSACCH is also dynamically activated using a specific algorithm (SRR orRLT).

The RSACCH and RDACCH are not linked.

RDFACCH and RSACCH can be activated only for calls using AMR-NB orAMR-WB.

Both features can be enabled at cell level.

Both features have been introduced in Rel-6 specifications and are

mandatory for Rel-6 MSs.


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Self-assessment on the Objectives

Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module

The form can be found in the first partof this course documentation


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End of ModuleRepeated ACCH


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Module 3NACC for Inter BSS and Inter RAT




TMO18090 Issue 1.0


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Base Station Subsystem BSS B10-B11 Telecom EvolutionsBSS B10-B11 Telecom Evolutions NACC for Inter BSS and Inter RAT

1 3 2

Blank Page




Document History


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1 3 3

Module Objectives


Describe the purpose of the "Inter-BSS/RAT NACC" feature and its Telecom

and O&M impacts


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1 3 4




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1 3 5

Table of Contents


1 What Is the Purpose of this Feature? 71.1 NACC in B10 81.2 Principle of NACC in B10 9

1.3 Principle of NACC in B11 112 How Does It Work? 122.1 Inter-BSS/RAT NACC Principles in B11 132.2 Inter-BSS/RAT Principles 152.3 Cell Reselection: 2G-to-2G Inter-BSS Cell Reselection 162.4 Cell Reselection: 3G-to-2G Cell Reselection 17

3 What Are the Telecom Impacts? 183.1 Inter-BSS/RAT NACC Principles 19

4 What Are the O&M Impacts? 204.1 Configuration Management 214.2 Performance Management 22


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1 3 8


1.1 NACC in B10

Do you remember NACC?Select t he corr ect st at ement s.

With NACC, the network can send SI1, SI3 and SI13 of target cell after PS cell reselection

The NACC is mandatory for Release 4 MSs supporting the GERAN feature Package 1

It has been introduced in ALU BSS B10 release

In B10, the NACC could occur only for a source and target cells mapped on the same GPU

In B10, the NACC could occur for a source and target cells mapped on 2 GPUs belongingto the same MFS

In B10, the NACC could occur for a source and target cells mapped on 2 GPUs belongingto different MFSs

SI1 and SI3 are provided by the BSC to the MFS, SI13 is built by the serving MFS


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1 3 9


1.2 Principle of NACC in B10

The NACC feature has beenintroduced in B9. Thisfeature allows to decreasethe GPRS service outage

during intra-BSS PS cellreselection, by providing theMS with a set of SystemInformation (SI) messages,required to access the newcell, before the MS leavesthe old cell.

BSS1 BSS1Cell A Cell B

BTS

A

BTS

B

SGSN

Throughput(Kbit/s)

Averagethroughput

t0

Reduced serviceoutage

Time(s)t1 t2 t3

Intra-BSS

The feature reduced the service outage time for an MS in packet transfer mode from a couple of seconds

down to 300-700 ms by giving the network a possibility to assist the MS before and during the cell change.The assistance is given as sending of neighbouring cell system information.


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1.3 Principle of NACC in B11

In B11, the benefits of NACC areextended to the inter-BSS and3G-to-2G Cell ReselectionCases. The NACC feature is

based on RAN InformationManagement (RIM), a genericmechanism for the exchange ofinformation between two RANnodes (GERAN or UTRAN). Withthe introduction of RIM-NACC,the GPRS service outage duringinter-BSS or inter-ratting PS cellreselection can also beimproved. In B11, the inter-BSSNACC can occur between 2 MFSs.

Cell A Cell B

BTS A BTS B

SGSN

Throughput(Kbit/s)

Averagethroughput

t0

Reduced serviceoutage

Time(s)t1 t2 t3

BSS1 BSS2

Inter-BSSPS cell reselection

is improved

The feature reduced the service outage time for an MS in packet transfer mode from a couple of seconds

down to 300-700 ms by giving the network a possibility to assist the MS before and during the cell change.The assistance is given as sending of neighbouring cell system information.


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2 How Does It Work?


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1 3 13

2 How Does It Work?

2.1 Inter-BSS/RAT NACC Principles in B11

What Is RIM?

The RAN Information Management (RIM) procedures provide a genericmechanism for the exchange of arbitrary information between two RAN

nodes, located either in a GERAN or in a UTRAN access network.

SGSN(s)

RAN-INFORMATION-

ACK

RAN-INFORMATION/Multiple Report

(ACK)

SI ChangeSI Request

RAN-INFORMATION-

REQUEST/MultipleReport

RAN-INFORMATION/

InitialMultiple Report

The SGSNssimply perform a relay

of the messages

Target BSSCurrent BSS

or RNC

The RAN Information Management (RIM) procedures allow to send information between BSCs/RNCs via one

or more SGSNs. The SGSNs simply perform a relay of the messages (possibly inter-SGSN). Any relationbetween messages is transparent for the SGSN.

Two main procedures are defined:

RAN Information Request procedure: initiated by a Controlling BSS/RNC when it requires information (inNACC case: SI) from another Serving BSS/RNC, or when it requires stop of event driven reports from another

Serving BSS/RNC.

RAN Information Send procedure: initiated by a Serving BSS when it has information to be sent toanother Controlling BSS/RNC. The procedure may be event-triggered (e.g. SI change) or scheduled (e.g. bya request procedure). Sending BSS may request acknowledgement of the information.

Routing and addressing of the messages are done through:

cell identifiers for the BSS.

A BSS is addressed by the Routing Area Identity (RAI) + Cell Identity (CI) of one of its cells.

RNC identifiers for RNC.

An RNC is addressed by the Routing Area Identity + RNC-Id.


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2 How Does It Work?

2.1 Inter-BSS/RAT NACC Principles in B11 [cont.]

What Is RIM?

The RAN Information Management (RIM) procedures provide a genericmechanism for the exchange of arbitrary information between two RAN

nodes, located either in a GERAN or in a UTRAN access network.

SGSN(s)

RAN-INFORMATION-

ACK

The SGSNssimply perform

a relay of the messages

RAN-INFORMATION/Multiple Report

(ACK)

SI ChangeSI Request

Target BSSCurrent BSS

or RNC

The RAN Information Management (RIM) procedures allow to send information between BSCs/RNCs via one

or more SGSNs. The SGSNs simply perform a relay of the messages (possibly inter-SGSN). Any relationbetween messages is transparent for the SGSN.

Two main procedures are defined:

RAN Information Request procedure: initiated by a Controlling BSS/RNC when it requires information (inNACC case: SI) from another Serving BSS/RNC, or when it requires stop of event driven reports from another

Serving BSS/RNC.

RAN Information Send procedure: initiated by a Serving BSS when it has information to be sent toanother Controlling BSS/RNC. The procedure may be event-triggered (e.g. SI change) or scheduled (e.g. bya request procedure). Sending BSS may request acknowledgement of the information.

Routing and addressing of the messages are done through:

cell identifiers for the BSS.

A BSS is addressed by the Routing Area Identity (RAI) + Cell Identity (CI) of one of its cells.

RNC identifiers for RNC.

An RNC is addressed by the Routing Area Identity + RNC-Id.


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2 How Does It Work?

2.2 Inter-BSS/RAT Principles

Have you understood the RIM procedure?Select t he corr ect st at ement s.

The RAN Information Management is an Alcatel-Lucent specific feature

The RIM procedure allows to send information between BSCs/RNCs via one or more SGSNs

This information may not be transparent for the SGSN

The RAN Information Send procedure is an event-triggered mechanism. It is used only when theset of NACC-related SI is changed

This procedure may be event triggered or scheduled

A BSS is addressed by the RAI + Cell Identity (CI) of one of its cells

An RNC is addressed by the RAI + RNC-Id+Cell Identity (CI) of one of its cells


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2 How Does It Work?

2.3 Cell Reselection:2G-to-2G Inter-BSS Cell Reselection

Inter-BSS NACC Procedure

In order to provide the MS with SI of external adjacent cells, thecurrent BSS/RNC shall obtain them from another target BSS, via the

SGSN. The RAN Information Management (RIM) procedure allows to sendinformation between BSCs/RNCs via one or more SGSNs. The RIM allowsa BSS to get System Information of 2G cells located in another BSS.

SGSN 1 SGSN 2

Serving cell Target cell

BSS 1 BSS 2

2G-to-2GPS Cell Reselection

RIM-NACCprocedure

In the inter-BSS case, the exchanges with the MS are the same as in Release 4 NACC.

In order to provide the MS with SI of external adjacent cells, the Controlling BSS shall obtain them fromanother Serving BSS, via the SGSN.

The RAN Information Management (RIM) procedure allows to send information between BSCs/RNCs via oneor more SGSNs. The SGSNs simply perform a relay of the messages (possibly inter-SGSN). Any relationbetween messages is transparent for the SGSN, i.e. a request/response exchange between RIM applications,

is routed and relayed as two independent messages by the SGSN.

Th

CE_TMO18090 BSS B10-B11 Telecom Evolution.pdf

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