Detailed Radio Planning

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



Introduction

Coverage Planning

CPICH signal level

CPICH quality

Pilot Pollution

SHO Zones

Parameter

Neighbour planning

Polygon planning



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


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


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


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:


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



Introduction

Coverage Planning

CPICH signal level

CPICH quality

Pilot Pollution

SHO Zones

Parameter

Neighbour planning

Polygon planning



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

f1f1

f1f1f1

Frequency assignment in GSM Frequency assignment in W-CDMA


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


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


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)


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


CPICH Ec/N0 plot exampleBefore After


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


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


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)



Introduction

Coverage Planning

CPICH signal level

CPICH quality

Pilot Pollution

SHO Zones

Parameter

Neighbour planning

Polygon planning



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


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


Handover status plot exampleBefore After



Introduction

Coverage Planning

CPICH signal level

CPICH quality

Pilot Pollution

SHO Zones

Parameter

Neighbour planning

Polygon planning



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


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


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


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


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


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


DB Parameter PlanningPolygon Planning

CPICH best server plot Polygons



Introduction

Coverage Planning

CPICH signal level

CPICH quality

Pilot Pollution

SHO Zones

Parameter

Neighbour planning

Polygon planning



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


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


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


Group 1 Group 512


512 Elements

Group #08 Elements

Group #638 Elements


512 Elements

Group #08 Elements

Group #638 Elements

8192 Downlink Scrambling Codes512 Groups with 16 Elements each

(1 primary, 15 secondary codes)



Group 1 Group 512


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


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:


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


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


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

Documents

Detailed Radio Planning