09 rn315410en10gla0 initial parameter planning

7/27/2019 09 RN315410EN10GLA0 Initial Parameter Planning

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Initial Parameter Planning

Customer confidential

1 © NSN Siemens Networks 3G Radio Planning Essentials / NPO Capability Development

3GRPESS – Module 9



Module 9 – Initial parameter planning

Objectives

After this module the participant shall be able to:-

• Understand the basic parameter settings required for

network launch





Module contents

• Scrambling Code Planning

• Neighbour List Planning

• Location, Routing and Service Area Planning



• UTRAN Registration Area Planning



Module contents









• 512 Primary scrambling codes are organised into 64 groups of 8

– Each Primary scrambling code has 15 Secondary scrambling codes

– Each Primary & Secondary scrambling code has left and right Alternate scrambling codes

• Scrambling code planning refers to assigning the Primary scrambling codes

• Each cell is assigned 1 Primary scrambling code

• Scrambling code planning strategies can be defined that maximise the number of neighbours

Introduction



,

different code groups – The difference between the two strategies remains unquantified in the field and is likely to depend upon UE

implementation

• Scrambling code planning requires co-ordination at international borders

• Scrambling code planning can be completed independently for each RF carrier

• Scrambling code planning can be completed using a radio network planning tool or a home madetool

• Scrambling code plan should account for future network expansion



Air-Interface BCCH Synchronisation (I)

Step 1

• Search for Primary Synchronisation Channel (P-SCH)

• Same chip sequence within every timeslot of every cell of every operator

• Chip sequence has length of 256 chips

• Provides slot synchronisation

2560 Chips 256 Chips



CP CP CP CP

P-SCH

Step 1 is the same for all scrambling code planning strategies



Air-Interface BCCH Synchronisation (II)

Step 2

• Search for Secondary Synchronisation Channel (S-SCH)

• Different series of 15 chip sequences for each code group

• Each chip sequence has a length of 256 chips• Select 1 out of 64 => relatively large probability of error

• Relatively low UE processing requirement relative to step 3

• Only necessary to identify 3 consecutive chip sequences to identify code group



• Provides frame synchronisation and identifies Primary scrambling code group

Cs1

2560 Chips 256 Chips

Cs2 Cs15 Cs1

Emphasis is placed on Step 2 if scrambling code plan maximises the number ofneighbours with different scrambling code groups



Air-Interface BCCH Synchronisation (III)

Step 3

• Search for CPICH

• Identifies Primary scrambling code

• Select 1 out of 8 => relatively low probability of error

• Relatively high UE processing requirement relative to step 2

• Not necessary to correlate complete 38400 chip frame to identify scrambling code

38400 Chips = 10 ms radio frame



CPICH

Emphasis is placed on Step 3 if scrambling code plan maximises the number ofneighbours with the same code group



Impact of Neighbour List Combining (I)

• When a UE is in soft handover then the RNC combines the neighbour listsbelonging to the active set cells

• It is necessary that duplicate scrambling codes do not appear within those lists

• Checks should be made to ensure that cells within potential active sets do nothave different neighbours with the same scrambling code

Example



ActiveRadiolink

ActiveRadiolink

UE in softhandover

Neighbour toactive set cell


code clashscenario 1

SC100 SC100



Impact of Neighbour List Combining (II)

• Checks should be made to ensure that no cells are neighboured to two or morecells which have neighbour lists including the same scrambling code for differenttarget cells


SC100Examplescramblingcode clashscenario 2



ct ve

Radiolink

UE in softhandover

Neighbour to

active set cell

SC100



Example Scrambling Code Plan

• Area with 12 Node B

• Strategy has been tominimise the number ofcode groups used inneighbouring cells

• Two code groups enough

Serving cell



IntraFreqNcell

ScrCode

Cluster of cellsusing 2 code

groups



Recommendations

• Isolation between cells assigned the same scrambling code should bemaximised

– isolation between cells assigned the same scrambling code sufficiently great toensure that a UE never simultaneously receives the same scrambling code from more

than 1 cell – isolation between cells assigned the same scrambling code sufficiently great to

ensure that a UE never receives a scrambling code from one cell while expecting toreceive the same scrambling code from second cell



network expansion.• The same scrambling code plan should be assigned to each RF carrier

• Scrambling code planning should be completed in conjunction with neighbour listplanning

• Scrambling code audits should be completed in combination with neighbour listaudits

• Checks should be made to ensure that no cells are neighboured to two or morecells which have neighbour lists including the same scrambling code for differenttarget cells



Module contents









Introduction

• Neighbour lists:

– 3G intra-frequency

– 3G inter-frequency

– 3G inter-system

– 2G inter-system

• High quality neighbour lists are critical to the performance of the network

• Neighbour lists are usually refined during pre-launch or post-launch optimisation



– Neighbour list planning should be as accurate as possible – Impact upon pre-launch optimisation has to be recognised

– Pre-launch optimisation often limited to specific drive route which may not identify allneighbours

– Neighbour list tuning usually achieves the greatest gains during pre-launch

optimisation

• Optimisation tools based upon RNC logging can also be used torefine neighbour lists subsequent to launch



3G Intra-Frequency Neigbour Lists

• Intra-frequency neighbours are used for cell re-selection, soft handover, softerhandover and intra-frequency hard handover

• Missing neighbours result in unnecessarily poor signal to noise ratios

CPICH Ec/Io SC100SC200

Drop

Cell

Selection

Time

Missing neighbours can be identified

from UE log files as a decrease inCPICH Ec/Io until connection dropsand then cell selection allows suddenimprovement

Exam le SC200 missin from



• Excessive number of neighbours

– increase the UE measurement time

– may lead to important neighbours being deleted during soft handover

• Intra-frequency neighbour lists are combined for both intra-RNC and inter-RNCsoft handover (assuming inter-RNC soft handover is supported)

• Intra-frequency neighbour lists are transmitted in SIB11 and dedicatedmeasurement control messages

neighbour list associated with SC100UE movement



Neighbour List CombiningIntra-Frequency Neighbours

• When a UE is in soft handover then the neighbour lists belonging to each of theactive set cells are combined

• Not all vendors offer neighbour list combining

• The RNC generates a new intra-frequency neighbour list after every active setupdate procedure (events 1a, 1b and 1c)

• The RNC transmits the new intra-frequency neighbour list to the UE if the newlist differs from the existing list



1. Active set cells

2. Neighbour cells which are commonto three active set cells

3. Neighbour cells which are commonto two active set cells

4. Neighbour cells which are definedfor only one active set cell

Generating a combined intra-frequency neighbour list

Update



Parameters

• Intra-Frequency neighbours are defined using the ADJS parameter set

• Each neighbour has its own set of ADJS parameters

RNC

Structure of databuild

• 3GPP allows the network to specify amaximum of 32 intra-frequency cells for the

UE to measure• Serving cell + 31

Intra-frequencyneighbours when notin soft handover

Intra-Frequency Neighbours



WCELL

ADJS

WBTS

HOPS 100

32

RTNRTHSDPA

RAS05 ADJS parameters

• 2-3 serving cells +30-29 neighbours insoft handover

• Size of SIB11 canlimit the number of

neighbours for cellre-selection



3G Inter-Frequency Neigbour Lists

• Inter-frequency neighbours are used for inter-frequency cell re-selection andinter-frequency handover

• The NSN RNC allows a maximum of 48 inter-frequency neighbours to bedefined with a maximum of 32 on any one RF carrier

– 3GPP specifies that a max. of 32 inter-frequency neighbours can be broadcast inSIB11

• NSN does not support

– inter-frequency handover from CELL_FACH



– inter-frequency handover while anchoring an RNC

• Excessive neighbours



• Inter-frequency neighbours are usually introduced after the network has beenlaunched and so refining them is usually a post launch optimisation task



Neighbour List CombiningInter-Frequency Neighbours

• When a UE is in intra-RNC soft handover then the neighbour lists belonging toeach of the active set cells are combined

• Neighbour lists are not combined for inter-RNC soft handover because the NSNRNC does not support inter-frequency neighbour signalling across the Iur


• Neighbour lists are not updated once compressed mode measurements havebegun, i.e. inter-frequency neighbour lists are dependant upon the active setcells when inter-fre uenc handover is tri ered



1. Neighbour cells which are commonto three active set cells

2. Neighbour cells which are commonto two active set cells


Generating a combined inter-frequency neighbour list

Inter-FrequencyNeighbour List



ParametersInter-Frequency Neighbours

• Intra-Frequency neighbours are defined using the ADJI parameter set

• Each neighbour has its own set of ADJI parameters

RNC


• Size of SIB11 can limit the number ofneighbours for cell re-selection



WCELL

ADJI

WBTS

HOPI 100

48

RTNRT

RAS05 ADJI parameters



3G Inter-System Neigbour Lists

• GSM neighbours are used for inter-system cell re-selection and inter-system handover

• 3GPP specifications allow a maximum of 32 inter-system neighbours to be defined

• Inter-system neighbours are broadcast in SIB11 for cell re-selection and are transmitted

in dedicated measurement control messages for inter-system handover• NSN does not support

– inter-system handover from CELL_FACH

– inter-system handover while anchoring an RNC



but one specific neighbour for BSIC verification• Excessive neighbours



• GSM neighbour lists can be based upon existing BSC 2G neighbour lists when sites areco-sited

• If an operator has both GSM900 and DCS1800 networks then it is possible to define inter-system neighbours only for the GSM900 layer or only for the DCS1800 layer



Neighbour List CombiningInter-System Neighbours

• When a UE is in intra-RNC soft handover then the neighbour lists belonging toeach of the active set cells are combined

• Neighbour lists are not combined for inter-RNC soft handover because the NSNRNC does not support inter-system neighbour signalling across the Iur


• Neighbour lists are not updated once compressed mode has begun, i.e. inter-system neighbour lists are dependant upon the active set cells when inter-s stem handover is tri ered



1. Neighbour cells which arecommon to three active set cells

2.Neighbour cells which arecommon to two active set cells


Generating a combined inter-system neighbour list

Inter-System

Neighbour List



ParametersInter-System Neighbours

• Intra-Frequency neighbours are defined using the ADJG parameter set

• Each neighbour has its own set of ADJG parameters

RNC


• Size of SIB11 can limit the number ofneighbours for cell re-selection



WCELL

ADJG

WBTS

HOPG 100

32

RTNRT

RAS05 ADJG parameters



Maximum Neighbour List Lengths (I)

• SIB11 is used to instruct UE which cells to measure in RRC Idle, CELL_FACH and CELL_PCH

• TS25.331 includes a contradiction made by 3GPP, i.e. SIB11 should be able to accommodateinformation regarding 96 cells, but SIB11 cannot exceed 3552 bits and this is insufficient toaccommodate information regarding 96 cells

• If a NSN RNC is configured with a cell which is configured with more neighbours than SIB11 can

accommodate then the cell is blocked and an alarm is raised• NSN has issued RNC Technical Note 46 to specify that when Hierarchical Cell Structure is disabled, a

maximum of 47 cells should be configured. This is a worst case figure and in general more cells can beincluded

• RU10 RNC su ort activation of SI11bis which enables transmission of all defined nei hbours



M a x i m u m S

i z e

o f S I B 1 1

AdjsAdji

Adjg

Complete set of

neighbours will not fit



Maximum Neighbour List Lengths (II)

• The size of SIB11 can be estimated from the number of intra-frequency, inter-frequency and inter-system neighbours

• The quantity of data associated with each neighbour can vary depending uponwhich information elements are included

AdjsQoffset1 or CPICH transmit Size of single ADJS

Example for intra-frequency neighbours



Neither No 48 bits

Either One No 48 or 56 bits (average of 55.2 bits)

Both No 56 or 64 bits (average of 62.1 bits)

Neither Yes average of 54.2 bits

Either One Yes average of 61.1 bits

Both Yes average of 68.0 bits



Maximum Neighbour List Lengths (III)

• Expression can be generated to identify whether or not a particular combination ofneighbours is likely to exceed the capacity of SIB11

)63()6.73()1.61(222_11

3552_11

ADJG ADJI ADJS SizeSIB

bitsSizeSIB

×+×+×+≈

<

• RAS05 includes parameters ADJS, ADJI and ADJG parameters:



• AdjsSIB

• AdjiSIB

• AdjgSIB

• These parameters allow larger neighbour lists to be defined for CELL_DCH byspecifying whether or not specific neighbours should be included in SIB11



2G Inter-System Neigbour Lists (I)

• BSC inter-system neighbours are used for inter-system cell re-selection andinter-system handover

• NSN’s implementation of the BSS allows the definition of 32 UMTS FDDneighbours

• The definition of 3G neighbours has an impact upon the maximum number ofGSM neighbours which can be defined within the BSC



Without 3G

neighbours

With 3G

neighbours

common BCCH

common BCCH

32 31

31 30



2G Inter-System Neigbour Lists (II)

• When a UE is in GSM idle mode, GPRS packet idle mode or GPRS packettransfer mode then it reads the 3G neighbour list from SI2quater and PSI3quatersystem information messages

• When a UE is in GSM connected mode then it reads the 3G neighbour list frommeasurement information messages which are sent on the SACCH

• The length of a single SI2quater message is not sufficient to accommodate 32inter-system neighbours

• A single SI2quater message is able to accommodate 10 3G neighbours. This



means a s ene c a ne g our s s can e m e o a eng o

• If multiple SI2quater messages are required then the UE must wait until it hasreceived the complete set before it is able to make a cell re-selection decision

• If neighbours are missing then UE may fail inter-system handovers and mayremain on the GSM system longer than necessary

• If 3G sites are co-sited with 2G sites then 3G neighbour lists configured withinthe BSC can be based upon the existing 2G neighbour lists



Typical Neighbour List Lengths

• Neighbour list lengths are scenario dependant

• Some examples

Urban

Suburban

3G

intra-freq

14

10

3G

inter-freq

3G

inter-sys

2G

inter-sys

14

10

14

10

16

12





Module contents









Introduction

• Location Areas (LA) and Routing Areas (RA) are used by the core network to track thelocation of a UE

• LA are used by the CS domain whereas RA are used by the PS domain

• Each core network service domain has its own independent state machine for each UE

• The main CS service states are CS-DETACHED, CS-IDLE and CS-CONNECTED

• The main PS service states are PS-DETACHED, PS-IDLE and PS-CONNECTED

Not registered

Iu signalling

connectionRegistered but no Iu

signalling connection



Node B

MSC

UE

RNC

Iu cs

SGSN

Single RRCConnection

Iu ps

CSstate

PSstate

CSstate

PSstate

Two IuSignalling

Connections Mobility Management (MM) Sublayer

Connection Management (CM) Sublayer

Session Management(SM) Entity

Call Control(CC) Entity

MobilityManagement(MM) Entity

GPRS MobilityManagement(GMM) Entity

Access Stratum

Non-Access Stratum

on- ccess ra um

• LA and RA arehandled by theNon-Access

Stratum layerwithin the UE andcore network



Location Areas

• A UE in CS IDLE state does not have to update the CS core of its locationwhen moving within a LA

• a LA consists of cells belonging to one or more RNCs that are connected to thesame CN node, i.e. one MSC/VLR

• The minimum size of a Location Area (LA) is a single cell• The maximum size of a LA is the collection of cells connected to a single VLR

• The mapping between a LA and its associated RNCs is handled by theMSC/VLR



• The mapping between a LA and its cells is handled by the RNC• A LA is identified globally using a Location Area Identification (LAI)

• The LAI is a concatenation of the Mobile Country Code (MCC), Mobile NetworkCode (MNC) and Location Area Code (LAC)

2 Bytes => 65336 values

Large number of LA per PLMN

00 00 and FF FE values are

reserved



Routing Areas

• A UE in PS IDLE state does not have to update the PS core of its location whenmoving within a RA

• a RA consists of cells belonging to one or more RNCs that are connected to thesame CN node, i.e. one SGSN

• The minimum size of a Routing Area is a single cell• A RA is always contained within a single LA

• it is possible for RA and LA to be defined to be equal

• The ma in between a RA and its associated RNCs is handled b the SGSN



• The mapping between a RA and its cells is handled by the RNC• A RA is identified globally using a Routing Area Identification (RAI)

• The RAI is a concatenation of the LAI and the Routing Area Code (RAC)

1 Byte => 256 values

Maximum of 256 RA per of LA



Paging Channel

• NSN RAN provides an 8 kbps PCH transport channel on the S-CCPCH

• 8 kbps is sufficient to include a single paging record per 10 ms

• A single cell can thus page 100 UE per second

• S-CCPCH can be shared with the FACH-c and FACH-u but PCH always has

priority

• Paging completed over either a Location Area, Routing Area, RNC or Cell

• Utilisation of paging capacity is maximised when paging is completed over a Cell



fach-PCH-InformationList {{

transportFormatSet commonTransChTFS : {

tti tti10 : {{

rlc-Size fdd : {

octetModeRLC-SizeInfoType2 sizeType1 : 4},

numberOfTbSizeList {

zero : NULL,one : NULL},

logicalChannelList allSizes : NULL

}},

Transmission Time

Interval = 10 ms

Transport Block Size =

(4 x 8) + 48 = 80 bits(equation from TS 25.331)

Maximum Transport Block

Set Size = 1 * 80 = 80 bits

URA_PCH RRC state

not currently

supported and sopaging does not

occur over a URA



Strategies (I)

• Small LA/RA – Improves paging capacity because each IDLE state paging message is broadcast by

fewer cells

– Increase in network signalling due to increased quantity of updates resulting frommobility

– Potential decrease in mobile terminated connection establishment success rate

– (Potential decrease in mobile originated connection establishment success rate)

• LA and RA can be planned to be relatively large while levels of



ra c are no oo grea

• Acceptable to plan location area across multiple RNC

– Generates paging per RNC for UE which are in RRC Connected Mode

• LA and RA commonly planned to be of equal size

Cell



Strategies (II)

• Possible to plan 2G and 3G networks using the LAI and RAI – Requires unique 2G and 3G Cell Identities (CI)

– Cell Global Identification (CGI) defined by

CGI must be unique



– core network is not able to distinguish between the two networks for pagingpurposes and both 2G and 3G paging appears on both the 2G and 3G networks

– less chance of a UE missing a paging message when it is completing inter-system cell re-selection

– increased quantity of paging on both systems and a requirement to co-ordinatecell identities. In practice it may be difficult to implement the same location areasfor 2G and 3G as a result of them not having the same coverage areas and notall sites being co-sited



Strategies (III)

• LA and RA boundaries used for the 2G system are likely to be relativelymature and may have already been optimised in terms of their locations

• This means that they provide a good starting point for the definition of 3G LAand RA boundaries.

• LA and RA boundaries should not run close to and parallel to major roads norrailways otherwise there is a risk of relatively large numbers of updates.

• Likewise, boundaries should not traverse dense subscriber areas



numbers of updates should be monitored to evaluate the impact of the updateprocedures.

• It is only necessary to decrease the size of a RA area relative to a LA if thereis a large quantity of paging from the PS service domain

• LA and RA boundaries should be accounted for during the clusteridentification task associated with pre-launch optimisation

• Clusters should be defined such that LA and RA boundaries are crossedduring drive tests. This helps to verify that the update procedures aresuccessful and do not have a significant impact upon services



Service Areas

• A Service Area (SA) is identified globally using its Service AreaIdentifier (SAI)

• The SAI is a concatenation of

– MCC + MNC + LAC + Service Area Code (SAC)

• Service areas are used for emergency service calls

• The SAC can be configured on a per cell basis with a value equalo he cell iden i CI . This hel s o sim lif s s em desi n

Customer confidential38 © NSN Siemens Networks 3G Radio Planning Essentials / NPO Capability Development

• RAN04 introduces the Service Area Broadcast (SAB) feature whichmakes use of a third S-CCPCH and Service Area Codes for SAB(SACB)

• A specific SAC can be assigned to multiple cells within a locationarea whereas a SACB must be unique for each cell within alocation area.



Module contents






URA PCH



URA_PCH state

• RU10 RNC support URA_PCH state transition

• The purpose of this state is to decrease the cell update signalingdue to cell reselection, which saves RNC and UE resources

• When the UE is in Cell_FACH or Cell_PCH state

– Location is known by the cell level

– Cell u dates sent b the UE when a cell re-selection occurs


• If too many cell updates (MaxCellReselections ) are received in apredefined time window (CellReselectionObservingTime ), the UEis ordered to transfer to URA_PCH state in order to reduce cellupdate signalling between the UE and RNC

• In URA_PCH state UE sends URA update to RNC after re-selection to new URA area

URA l i



URA planning

• The planning of URA involves a balance between paging load andsignalling load

– Large URA : Paging load increases

– Small URA : Frequent URA updates, signalling load and also UE powerconsumption increases

• Multiple URA Ids can be configured


– Reduces possible ping-pong betweenURA areas

• Initially URA can be designed RNCwide

– Simple design, each RNC area with differentURA Id

– URA can be optimised with counter info

M d l 9 I iti l t l i



Module 9 – Initial parameter planning

Summary

• The initial parameter planning includes configuration of

essential parameters that are required for network launch

• Groups of parameters that are dependent on the

network layout


• Most parameters are configured as default

09 rn315410en10gla0 initial parameter planning

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