10 rn3154aen10gla0 initial parameter planning
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Initial Parameter Planning3GRPESS Module 9
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Module 9 Initial parameter planning
Objectives
After this module the participant shall be able to:-
Understand the basic parameter settings required for
network launch
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Module contents
Scrambling Code Planning
Neighbour List Planning
Location, Routing and Service Area Planning
UTRAN Registration Area Planning
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Module contents
Scrambling Code Planning
Neighbour List Planning
Location, Routing and Service Area Planning
UTRAN Registration Area Planning
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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
belonging to the same code group, or that maximise the number of neighbours that belong todifferent code groups
The difference between the two strategies remains unquantified in the field and is likely to depend upon UEimplementation
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 made
tool
Scrambling code plan should account for future network expansion
Introduction
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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
CP
2560 Chips 256 Chips
CP CP CP
P-SCH
Step 1 is the same for all scrambling code planning strategies
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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
C s1
2560 Chips 256 Chips
C s2 C s15 C s1
Emphasis is placed on Step 2 if scrambling code plan maximises the number ofneighbours with different scrambling code groups
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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
CPICH
38400 Chips = 10 ms radio frame
Emphasis is placed on Step 3 if scrambling code plan maximises the number of
neighbours with the same code group
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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 not
have different neighbours with the same scrambling code
ActiveRadiolink
ActiveRadiolink
UE in softhandover
Neighbour toactive set cell
Neighbour toactive set cell
Examplescramblingcode clashscenario 1
SC100 SC100
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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
ActiveRadiolink
UE in softhandover
Neighbour toactive set cell
Neighbour toactive set cell
SC100
SC100Examplescramblingcode clashscenario 2
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Example Scrambling Code Plan
Area with 12 Node B
Strategy has been tominimise the number ofcode groups used inneighbouring cells
Two code groups enoughup to 15 neighbours
6 7
2 0
1 2
0 2 4
2 3 8
1 0
41 7
1 1
2 5 3
1 8 5
1 9
9
2 2 2 1
1 2 2 6
1 6 1 5
1 4
1 3
2 7
2 9
2 8
3 0
3 1
3 2
3 3
3 4
3 5
IntraFreqNcellScrCode
UE
Serving cell
Cluster of cellsusing 2 code
groups
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Recommendations
Isolation between cells assigned the same scrambling code should bemaximised isolation between cells assigned the same scrambling code sufficiently great to
ensure that a UE never simultaneously receives the same scrambling code from morethan 1 cell
isolation between cells assigned the same scrambling code sufficiently great toensure that a UE never receives a scrambling code from one cell while expecting toreceive the same scrambling code from second cell
Specific scrambling codes should be excluded from the plan to allow for futurenetwork expansion.
The same scrambling code plan should be assigned to each RF carrier Scrambling code planning should be completed in conjunction with neighbour list
planning Scrambling code audits should be completed in combination with neighbour list
audits Checks should be made to ensure that no cells are neighboured to two or more
cells which have neighbour lists including the same scrambling code for differenttarget cells
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Module contents
Scrambling Code Planning
Neighbour List Planning
Location, Routing and Service Area Planning
UTRAN Registration Area Planning
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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 all
neighbours Neighbour list tuning usually achieves the greatest gains during pre-launch
optimisation Optimisation tools based upon RNC logging can also be used to
refine neighbour lists subsequent to launch
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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
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 dedicated
measurement control messages
CPICH Ec/Io SC100SC200
Drop
CellSelection
Time
Missing neighbours can be identifiedfrom UE log files as a decrease inCPICH Ec/Io until connection dropsand then cell selection allows suddenimprovement
Example SC200 missing fromneighbour list associated with SC100UE movement
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Parameters
Intra-Frequency neighbours are defined using the ADJS parameter set Each neighbour has its own set of ADJS parameters
WCELL
ADJS
WBTS
RNC
HOPS 100
32
RTNRTHSDPA
Structure of databuild
RAS05 ADJS parameters
3GPP allows the network to specify amaximum of 32 intra-frequency cells for theUE to measure
Serving cell + 31Intra-frequencyneighbours when notin soft handover
2-3 serving cells +30-29 neighbours insoft handover
Size of SIB11 canlimit the number of
neighbours for cellre-selection
Intra-Frequency Neighbours
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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 in
SIB11
NSN does not support inter-frequency handover from CELL_FACH inter-frequency handover while anchoring an RNC
Excessive neighbours increase the UE measurement time may lead to important neighbours being deleted during soft handover
Inter-frequency neighbours are usually introduced after the network has beenlaunched and so refining them is usually a post launch optimisation task
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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 Not all vendors offer neighbour list combining
Neighbour lists are not updated once compressed mode measurements havebegun, i.e. inter-frequency neighbour lists are dependant upon the active setcells when inter-frequency handover is triggered
1. Neighbour cells which are commonto three active set cells
2. Neighbour cells which are commonto two active set cells
3. Neighbour cells which are definedfor only one active set cell
Generating a combined inter-frequency neighbour list
Inter-FrequencyNeighbour List
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ParametersInter-Frequency Neighbours
Intra-Frequency neighbours are defined using the ADJI parameter set Each neighbour has its own set of ADJI parameters
WCELL
ADJI
WBTS
RNC
HOPI 100
48
RTNRT
Structure of databuild
RAS05 ADJI parameters
Size of SIB11 can limit the number ofneighbours for cell re-selection
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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 transmittedin 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
The NSN RNC instructs the UE to measure all GSM neighbours for RSSI measurementsbut one specific neighbour for BSIC verification
Excessive neighbours increase the UE measurement time may lead to important neighbours being deleted during soft handover
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
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ParametersInter-System Neighbours
Intra-Frequency neighbours are defined using the ADJG parameter set Each neighbour has its own set of ADJG parameters
WCELL
ADJG
WBTS
RNC
HOPG 100
32
RTNRT
Structure of databuild
RAS05 ADJG parameters
Size of SIB11 can limit the number ofneighbours for cell re-selection
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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 accommodate
information 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 canaccommodate 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, amaximum of 47 cells should be configured. This is a worst case figure and in general more cells can beincluded
RU10 RNC support activation of SI11bis, which enables transmission of all defined neighbours
M a x i m u m
S i z e o
f S I B 1 1
Adjs Adji
Adjg
Complete set ofneighbours will not fit
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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 orAdjsQoffset2 included
CPICH transmitpower included
Size of single ADJS
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
Example for intra-frequency neighbours
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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
+++
65336 values
Large number of LA per PLMN00 00 and FF FE values arereserved
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Routing Areas A UE in PS IDLE state does not have to update the PS core of its location when
moving within a RA a RA consists of cells belonging to one or more RNCs that are connected to the
same 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 mapping between a RA and its associated RNCs is handled by 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
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Paging Channel
fach-PCH-InformationList{{
transportFormatSet commonTransChTFS : {tti tti10 : {
{rlc-Size fdd : {
octetModeRLC-SizeInfoType2 sizeType1 : 4},
numberOfTbSizeList {zero : NULL,one : NULL},
logicalChannelList allSizes : NULL}
},
From SIB 5
Transmission TimeInterval = 10 ms
Transport Block Size =(4 x 8) + 48 = 80 bits(equation from TS 25.331)
Maximum Transport BlockSet Size = 1 * 80 = 80 bits
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
URA_PCH RRCstate not currently
supported and sopaging does notoccur over a URA
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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
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
CGI must beunique
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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 Cells which are located at a LA or RA boundary and which experience large
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
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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 equal
to the cell identity (CI). This helps to simplify system design
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.
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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 updates sent by 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
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URA planning
The planning of URA involves a balance between paging load and
signalling load Large URA : Paging load increases Small URA : Frequent URA updates, signalling load and also UE power
consumption increases
Multiple URA Ids can be configuredfor each cell Reduces possible ping-pong between
URA areas
Initially URA can be designed RNCwide Simple design, each RNC area with different
URA Id URA can be optimised with counter info
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Module 9 Initial parameter planning
Summary
The initial parameter planning includes configuration ofessential parameters that are required for network launch
Groups of parameters that are dependent on the
network layout
Most parameters are configured as default
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