Detailed Radio PlanningOverview
Com MN PG NT NE 2
Enabling Workshop, Berlin, January 2005
© Siemens Com MN PG NT NE 2 12/01/2005 2ICM N PG NM NE P1 12/01/2005
OutlineDetailed Radio Planning
Introduction
Coverage Planning
CPICH signal level
CPICH quality
Pilot Pollution
SHO Zones
Parameter
Neighbour planning
Polygon planning
Scrambling Codes Planning
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OutlineDetailed Radio Planning
Introduction
Coverage Planning
CPICH signal level
CPICH quality
Pilot Pollution
SHO Zones
Parameter
Neighbour planning
Polygon planning
Scrambling Codes Planning
© Siemens Com MN PG NT NE 2 12/01/2005 4ICM N PG NM NE P1 12/01/2005
Introduction Radio Planning – Preparation
Radio Planning Tool PreparationDTM (Digital Terrain Maps)Propagation model tuning
Traffic Maps – based on the input from marketing group
Strategic planning parametersAntenna height level Types of antennas Tilting strategyDiversity strategySite configuration (e.g. Node B type, TMA)Migration Strategy
Rough estimations Link Budget calculation -> number of sites, gridCapacity calculation -> number of carriers, expected loadCHC calculation -> estimation of HW requirements
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Tool Supported Radio PlanningTasks
Initial Plan
Determination of ideal geographical sites position
Initial site layout definition (antenna height, directions, types and tilts for each site)
Final Plan
Evaluation of real site locations
And their integration in network plan
Final site layout definition
DB parameters planning
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Tool Supported Radio Planning Objectives
CPICH coverage ensured
Clear CPICH best server areas
Dedicated channels coverage in UL and DL ensured
Required Capacity in UL and DL ensured
Optimized number of required HW resources
Minimize the number of sites and their configuration including the base band resources
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Tool Supported Radio Planning Initial Network Plan Tuning
Number of Sites
Change of the initial grid
Addition / Deletion of single sites
Sites position
Violation in regular grid
Antenna parameters
Type, height, direction, tilt
Tuning of the network plan can be performed by adjustments of the following parameters:
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Tool Supported Radio PlanningEvaluation of the network plan
Statistics
Overall and per cell – quick problem zones identification
Served users statistics – e.g. handover status info
Dropped users statistics – indication of the failure reason
Plots
Visualization of planning results
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OutlineDetailed Radio Planning
Introduction
Coverage Planning
CPICH signal level
CPICH quality
Pilot Pollution
SHO Zones
Parameter
Neighbour planning
Polygon planning
Scrambling Codes Planning
© Siemens Com MN PG NT NE 2 12/01/2005 10ICM N PG NM NE P1 12/01/2005
Interference in FDD networksInterference is a peculiarity of CDMA technology
The same frequency carrier is reused on all sites
Interference should be however reduced in order to improve the system capacity and quality
f1f3f4
f5f6f7
f2
f1f3f4
f5f6f7
f2f1
f3f4
f5f6f7
f2
f1f3f4
f5f6f7
f2f1
f3f4
f5f6f7
f2
f1f3f4
f5f6f7
f2f1
f3f4
f5f6f7
f2 f1f1
f1f1
f1f1f1
f1f1
f1f1
f1f1f1
f1f1
f1f1
f1f1f1
f1f1
f1f1
f1f1f1
f1f1
f1f1
f1f1f1
f1f1
f1f1
f1f1f1
f1f1
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f1f1f1
Frequency assignment in GSM Frequency assignment in W-CDMA
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CPICH Coverage planningBest Server plot
Homogeneous and regular shapes of cells
Coverage spots of the not immediate pilots (alternating pilots) to be avoided
FDD rules similar to GSM however much more strict
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CPICH Best Server plot exampleBefore After
Introduced changed:- Addition of new sites, - Change of antenna directions on existing sites - Adjustments of tilts on further sites
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CPICH Coverage planning …CPICH Signal Strength
In the planned area Signal level shall be kept on the agreed level
Indoor loses and fading margin to be considered
Signal strength to be also analyzed separately for each site
Good signal level present in the best server area
Low signal level outside of the best server area
To avoid alternating best server areas
To reduce interfere (pilot pollution)
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CPICH Quality planning
Agreed CPICH Ec/No level to be reached on most of the area
CPICH Ec/No target value depends on the expected quality
can also be different in different areas
One can assume that
Ec/No ~ -15dB ensures a good quality
Ec/No ~ -18dB allows worse quality
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CPICH Ec/N0 plot exampleBefore After
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Pilot PollutionPilot polluter – other cell CPICH signal which is not in active set and which Ec/No differs not much form the serving one/ones
Interference situation is the best if there is a clear dominating CPICH signal at each point of the planned area
Dominating CPICH signal differs much from the other CPICH signals received at a certain position
No or only few Polluters at each position
In SHO area active set CPICH signals to be easy distinguishable
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CPICH polluters plot example
Pilot polluter (absolute) threshold of -24dB in this example <- this is a low value of this parameter Normally few thresholds settings should be analyzed to be able to judge about situation
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Interference reduction
Planning of the best server CPICH signal
But also: planning of second and third best CPICH signals
Control over polluters coverage
Use of electrical vs. mechanical tilt
Electrical tilting results in a suppression of the back and side antenna lobes and homogenous scaling of the antenna patterns
Back lobe reduction in the real network deployment
Impact of antenna configuration (i.e. mounting of antennas against the wall instead of on poles where possible, use of screens)
© Siemens Com MN PG NT NE 2 12/01/2005 19ICM N PG NM NE P1 12/01/2005
OutlineDetailed Radio Planning
Introduction
Coverage Planning
CPICH signal level
CPICH quality
Pilot Pollution
SHO Zones
Parameter
Neighbour planning
Polygon planning
Scrambling Codes Planning
© Siemens Com MN PG NT NE 2 12/01/2005 20ICM N PG NM NE P1 12/01/2005
Soft Handover Area Planning
Optimisation of SHO parameter is necessary because the best compromise between the two extremes must be found :
Small SHO area
•low number of users in SHO
•positive effects from SHO *) cannot be effectively used
Large SHO area
•high number of users in SHO
•to much system capacity is needed
Tradeoff
*) gain against slow fading, additional macro diversity
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Soft Handover Area Planning
SHO zones should have regular shapes
Not too many branches
Two- and three-way handovers lead usually to the highest handover gains
Usually the best situation is when ~ 30% of users are in SHO
Can be checked with statistics
First of all Soft handover area must be planned correctly
DB parameter tuning is the next step
Without the correctly planed Soft handover areas tuning of the DB parameters will not be effective
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Handover status plot exampleBefore After
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OutlineDetailed Radio Planning
Introduction
Coverage Planning
CPICH signal level
CPICH quality
Pilot Pollution
SHO Zones
Parameter
Neighbour planning
Polygon planning
Scrambling Codes Planning
© Siemens Com MN PG NT NE 2 12/01/2005 24ICM N PG NM NE P1 12/01/2005
DB Parameter Planning Neighbour planning
Inter-frequency HO
Softer HO Soft HO
Intra-frequency HOTriggered by radio conditions
Triggered by load and coverage
Intersystem HOTriggered by limitedcoverage of UMTS
GSM
UMTS cells
UMTS cells
GSM
Handover Control Overview
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RNC
AccessControl
Node BNode B
DB Parameter Planning Neighbour planning - O&M Parameter Overview
CELLGeneral
InformationNAS
Information
GeographicalData
Cell Re-Selection
Adjacent UTRAN Cell
Adjacent GSM Cell
Admission Control
Congestion Control
Outer Loop Power Control
IntrafrequencyHandover
RLTimer
UL Common Channel
UE Timer
Radio BearerControl
External UTRAN Cell
External GSM Cell
GeneralInformation
HCS Control
AdjacentRNC
DL Common Channel
DL Common Channel
InterfrequenyHandover
InterSystemHandover
AccessControl
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DB Parameter Planning Neighbour planning
Intrafrequency Neighbours
Planned in such a way that the UE moving through the area of multiple cells can keep its connection running
Distant (not immediate) neighbours even of a strong signal shall be planned with care as SHO with them can lead to high interference
Interfrequency Neighbours
In UMR3.5: Cells sharing but also not sharing one antenna to be interfrequency neighbours
Intersystem Neighbours
Planned in such a way that the GSM network is a fallback solution in case of coverage hole in the FDD network or End of FDD network coverage
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DB Parameter Planning Neighbour planning (See also further presentations)
RNC DB limitation
Max 32 FDD (intrafrequency and interfrequency together) neighbours can be defined per one FDD cell in DB
Max 32 GSM neighbours per one FDD cell
UE limitation
UE can store information of Max 32 intrafrequency, 32 interfrequency and 32 GSM neighbors
If too many neighbours per cell are defined, there may be a problem if the UE is in SHO
If the total number is higher than 32 remaining neighbours will not be sent to the UE
32 is a relatively high number so is a normal case this limitation is not critical
Keep the number of neighbours per cell reasonable low
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DB Parameter PlanningNeighbour planning
It is possible to differentiate between Neighbours for:
Handover
Cell Reselection
Both (Handover and Reselection) -> the usual case
Automatic planning of the neighbours is possible with the use of Ratio Planning Tools
Neighbour plan to be periodically verified with system statistics
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DB Parameter PlanningPolygon Planning
Polygon planning is required for the LCS feature
LCS provides the capability to determine the geographic location of the user equipment
Polygon description of cell coverage area, with it position of the user can be determined as well as accuracy of this position can be estimated
Task of the polygon planning is to:
Create polygons having maximum 15 corner points to represent thecoverage areas of particular cells
Parameters required per corner point of each polygon
Number of Corner Point
Degrees of Latitude
Degrees of Longitude
Polygon planning is tool supported
cell polygon: definition throughlist of corner points
+centre point
polygon border line
centre point
accuracyradius
polygon corner point
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DB Parameter PlanningPolygon Planning
CPICH best server plot Polygons
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OutlineDetailed Radio Planning
Introduction
Coverage Planning
CPICH signal level
CPICH quality
Pilot Pollution
SHO Zones
Parameter
Neighbour planning
Polygon planning
Scrambling Codes Planning
© Siemens Com MN PG NT NE 2 12/01/2005 32ICM N PG NM NE P1 12/01/2005
Spreading (Channelization)Transforms each data bit into a sequence of ‚chips‘
Applies orthogonal variable spreading factor (OVSF) codes
Increases the signal bandwidth
Scrambling (Randomization)Chip-wise operation on data
No further bandwidth increase
Spreading and Scrambling Principle
DATA
Bit Rate Chip Rate Chip Rate
Channelization Code Scrambling Code
DATA
Bit Rate Chip Rate Chip Rate
Channelization Code Scrambling Code
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Downlink (Node B)Unique scrambling assigned per cell
Planning topic during network design
Uplink (UE, call)Scrambling code dynamically assigned by UTRAN
Used scrambling codes associated to DL scrambling code
Scrambling Code Assignment
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DL Scrambling Codes
Associated to the 0 to 8191 DL codes:
Scrambling codes 8192, 8193, …, 16383 are reserved for DL channels using compressed mode (left alternate scrambling code).
Scrambling codes 16384, 16385, …, 32767 are reserved for DL channels using compressed mode (right alternate scrambling code).
Group of Primary Scrambling Codes
512 Elements
Group #08 Elements
Group #638 Elements
8192 Downlink Scrambling Codes512 Groups with 16 Elements each
(1 primary, 15 secondary codes)
#0 primary15 secondary
#511 primary15 secondary
Group 1 Group 512
Group of Primary Scrambling Codes
512 Elements
Group #08 Elements
Group #638 Elements
Group of Primary Scrambling Codes
512 Elements
Group #08 Elements
Group #638 Elements
8192 Downlink Scrambling Codes512 Groups with 16 Elements each
(1 primary, 15 secondary codes)
#0 primary15 secondary
#511 primary15 secondary
Group 1 Group 512
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DL Scrambling Codes
........1 2 3 40 5
11
512 Downlink Primary Scrambling Codes
1 2 3 40 8192
5 6 7 8 9 10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33 ...
15 Secondary Codes per Primary Code........
......
........1 2 3 40 5
11
1 2 3 40 511
512 Downlink Primary Scrambling Codes
1 2 3 40 8192
5 6 7 8 9 10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33 ...
15 Secondary Codes per Primary Code........
......
Grouped into 64 groups of 8 primary
scrambling codes each
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DL Scrambling Code Planning
One scrambling code has to be assigned to one cell.Two cells in the same sector, but different carriers, can have the same scrambling code
Reuse of 512 (# primary scrambling codes) is possible.
Neighboring cells and neighbors of neighbors shall not have the same downlink scrambling code
Special scrambling code group assignment strategies might be useful
Depending on the cell search algorithm in the UE
E. g. Reuse of 64 code groups, assign only the first SC
1,21,4
1,51,7
1,1 1,61,3
1,21,4
1,51,7
1,1 1,61,3
1,21,4
1,51,7
1,1 1,61,3
UEUE
Sub-optimal SC group allocation
2,14,1
5,17,1
1,1 6,13,1
2,14,1
5,17,1
1,1 6,13,1
2,14,1
5,17,1
1,1 6,13,1
UEUE
Optimal SC group allocation
EXAMPLE:
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DL Scrambling Code Planning
Scrambling code planning at neighboring country borders
Fulfilment of maximum allowable signal strength at country border
Co-ordination of scrambling codes in border areas with neighbour operator
Summary DL code planning:
Scrambling code planning is a similar task as frequency planning in GSM, but much less complex due to higher reuse
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UMTS FDD planning
Planning of the 3G networks is different from GSM networks planning
Interference consideration must be serious
Planning of best server but also of pilot polluters
Traffic modeling is important 3G networks as it has a direct impact on interference
HW Planning
Number of carriers
Planning of base band hardware (channel cards)
SHO areas planning
Polygon
SC planning
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More detailed description of the presented issues can be found in a document “Customer Documentation – Radio Network Planning”
For Scrambling code planning please refer also to:
https://ims.icn.siemens.de/livelink/livelink/Open/322483992
https://ims.icn.siemens.de/livelink/livelink/Open/324100633