WCDMA RNP Cell Primary Scrambling Code Planning Guidance

Product name Confidentiality level

WCDMA RNP For internal use only

Product version Total 31pages

V100R001

WCDMA RNP Cell Primary

Scrambling Code Planning

Guidance

For internal use only

Prepared by URNP-SANA Date 2003-04-24

Reviewed by Date

Reviewed by Date

Granted by Date

Huawei Technologies Co., Ltd.

All rights reserved

WCDMA RNP Cell Primary Scrambling Code Planning Guidance For internal use only

10-4-30 All rights reserved. Page 2 of 31

Revision record

Date Revision version

Revision Description Author

2003-04-24 1.00 Initial transmittal Chen Qi

2004-07-19 2.00 Change the version, no content updated. Qinyan



Table of Contents

1 Overview .................................................................................................................................................... 7

1.1 Objective ............................................................................................................................................... 7

1.2 Planning Principles ................................................................................................................................ 8

1.3 Planning Method ................................................................................................................................... 9

2 Preparations for Applying Cell PSC Planner Tool ................................................................................... 10

2.1 Checking PLMN Network Setup ........................................................................................................ 10

2.2 Checking BS Setup and Cell Distribution on Map .............................................................................. 12

2.3 Checking whether 3g Carrier is Set up and Added to Cell .................................................................. 13

2.4 Checking Cell Coverage Predictor ...................................................................................................... 14

3 Operation Process of Cell PSC Planner Tools ......................................................................................... 14

3.1 Setting Cell Range for Planning .......................................................................................................... 14

3.2 Automatic Planning of Intra-carrier Neighboring Cells ...................................................................... 15

3.3 Setting Schemas of Scrambling Code Group and Scrambling Code ................................................... 17

3.4 Run the UMTS Scrambling Code Planner Tool .................................................................................. 17

3.4.1 Step 1 .................................................................................................................................... 18

3.4.2 Step 2 .................................................................................................................................... 18

3.4.3 Step 3 .................................................................................................................................... 20

3.4.4 Step 4 .................................................................................................................................... 21

4 Analysis on Cell PSC Planning ................................................................................................................ 24

4.1 Analysis on Scrambling Code Planning Report Generated Automatically ......................................... 24

4.1.1 Setting of Relevant Parameters......................................................................................... 24

4.1.2 Adjustment Method.............................................................................................................. 25

4.1.3 Example of Code Resource Reuse ................................................................................... 26

4.2 Analysis on Manual Configuration of Cell PSCs ................................................................................ 28

4.2.1 Determining the Code Resource to be Used ................................................................... 28

4.2.2 Planning Method .................................................................................................................. 29

4.3 Minimum Reuse Distance and Scrambling Code Resource Reservation ............................................ 30



List of Tables

Table 1 Primary Scrambling Code ............................................................................................................. 7

Table 2 The Parameters in scrambling code planner................................................................................. 24



List of Figures

Figure 1 PLMN ....................................................................................................................................... 11

Figure 2 NodeBs&Cells ........................................................................................................................... 13

Figure 3 Carriers .................................................................................................................................... 14

Figure 4 Coverage Predictor .................................................................................................................... 14

Figure 5 Filters ....................................................................................................................................... 15

Figure 6 Neighbour Planner ..................................................................................................................... 16

Figure 7 Code Schemas ......................................................................................................................... 17

Figure 8 Scrambling code planner ............................................................................................................ 18

Figure 9 Scrambling code planner: step1 .................................................................................................. 18


Figure 11 Scrambling Code planner: step3 ................................................................................................. 20


Figure 13 For example: NanJing Coverage ................................................................................................. 27

Figure 14 For example: NanJing PSC Planning (CodeGroup.Code) .............................................................. 28

Figure 15 Manual PSC Planning ................................................................................................................ 29

Figure 16 Minimize Reuse Distance ........................................................................................................... 30



WCDMA RNP

Cell Primary Scrambling Code Planning Guideline

Key word: Spread code, scrambling code, cell primary scrambling code

Abstracts: This document presents the allocation principles for cell primary scrambling code in

the WCDMA network, and introduces the method for the tool of automatic allocation

scrambling codes.

List of abbreviations: Omitted.



1 Overview

1.1 Objective

This document is to be a guide of RNP engineers for the radio network planning work. The

purpose of this document is to present how to plan the cell primary scrambling codes (PSC), by

means of automatic planning with the network planner tool or manually planning.

The uplink scrambling codes range from 0 to 224

-1. The RNC selects and assigns them

randomly, so that the users can be identified in uplink easily without planning. In the realization,

different SPU sub-systems of different BM frames in a single RNC on the RAN side segment the

uplink scrambling codes. When accessing the system from the subscriber queries according to

the SpuCpuId the uplink scrambling code segment numbers that this SPU can assign. Then the

segment number will be used to generate uplink scrambling codes within the corresponding

range randomly,

The downlink scrambling codes, referring to long scrambling codes only, range from 0

to 218

-1. However, in order to speed up the cell searching procedure, only 8192 codes can be

used. These 8192 codes are divided into 512 groups, each of which contains 16 scrambling

codes. The first scrambling code of each group is called primary scrambling code (PSC), and the

other 15 ones are secondary scrambling codes (SSC). So there are 512 PSCs in all, as shown in

the following table. The 512 PSCs are also divided into 64 groups, each of which contains 8

PSCs. Network planning is required for the downlink to identify the cells, so as to ensure any two

intra-frequency cells interfering to each other do not have identical PSCs. In downlink, the user is

identified with the channel codes. Each scrambling code corresponds to one channel code tree.

Every user can use the cell PSC for scrambling. If the number of users in this cell exceeds a

certain value, SSC must be used for scrambling. Besides SCH,

PCCPCH/PCPICH/PICH/AICH/SCCPCH in the downlink uses the downlink PSC or SSC for

scrambling, and will repeat in every frame, so that the UE can find the proper scrambling code.

For the scrambling code analysis, refer to Reference [1].

Table 1 Primary Scrambling Code

Primary scrambling

code/scrambling group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

PSC_1 0 128 256 384 512 640 768 896 1024 1152 1280 1408 1536 1664 1792 1920

PSC_2 16 144 272 400 528 656 784 912 1040 1168 1296 1424 1552 1680 1808 1936

PSC_3 32 160 288 416 544 672 800 928 1056 1184 1312 1440 1568 1696 1824 1952

PSC_4 48 176 304 432 560 688 816 944 1072 1200 1328 1456 1584 1712 1840 1968

PSC_5 64 192 320 448 576 704 832 960 1088 1216 1344 1472 1600 1728 1856 1984

PSC_6 80 208 336 464 592 720 848 976 1104 1232 1360 1488 1616 1744 1872 2000

PSC_7 96 224 352 480 608 736 864 992 1120 1248 1376 1504 1632 1760 1888 2016



PSC_8 112 240 368 496 624 752 880 1008 1136 1264 1392 1520 1648 1776 1904 2032

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

2048 2176 2304 2432 2560 2688 2816 2944 3072 3200 3328 3456 3584 3712 3840 3968

2064 2192 2320 2448 2576 2704 2832 2960 3088 3216 3344 3472 3600 3728 3856 3984

2080 2208 2336 2464 2592 2720 2848 2976 3104 3232 3360 3488 3616 3744 3872 4000

2096 2224 2352 2480 2608 2736 2864 2992 3120 3248 3376 3504 3632 3760 3888 4016

2112 2240 2368 2496 2624 2752 2880 3008 3136 3264 3392 3520 3648 3776 3904 4032

2128 2256 2384 2512 2640 2768 2896 3024 3152 3280 3408 3536 3664 3792 3920 4048

2144 2272 2400 2528 2656 2784 2912 3040 3168 3296 3424 3552 3680 3808 3936 4064

2160 2288 2416 2544 2672 2800 2928 3056 3184 3312 3440 3568 3696 3824 3952 4080

32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

4096 4224 4352 4480 4608 4736 4864 4992 5120 5248 5376 5504 5632 5760 5888 6016

4112 4240 4368 4496 4624 4752 4880 5008 5136 5264 5392 5520 5648 5776 5904 6032

4128 4256 4384 4512 4640 4768 4896 5024 5152 5280 5408 5536 5664 5792 5920 6048

4144 4272 4400 4528 4656 4784 4912 5040 5168 5296 5424 5552 5680 5808 5936 6064

4160 4288 4416 4544 4672 4800 4928 5056 5184 5312 5440 5568 5696 5824 5952 6080

4176 4304 4432 4560 4688 4816 4944 5072 5200 5328 5456 5584 5712 5840 5968 6096

4192 4320 4448 4576 4704 4832 4960 5088 5216 5344 5472 5600 5728 5856 5984 6112

4208 4336 4464 4592 4720 4848 4976 5104 5232 5360 5488 5616 5744 5872 6000 6128

48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63

6144 6272 6400 6528 6656 6784 6912 7040 7168 7296 7424 7552 7680 7808 7936 8064

6160 6288 6416 6544 6672 6800 6928 7056 7184 7312 7440 7568 7696 7824 7952 8080

6176 6304 6432 6560 6688 6816 6944 7072 7200 7328 7456 7584 7712 7840 7968 8096

6192 6320 6448 6576 6704 6832 6960 7088 7216 7344 7472 7600 7728 7856 7984 8112

6208 6336 6464 6592 6720 6848 6976 7104 7232 7360 7488 7616 7744 7872 8000 8128

6224 6352 6480 6608 6736 6864 6992 7120 7248 7376 7504 7632 7760 7888 8016 8144

6240 6368 6496 6624 6752 6880 7008 7136 7264 7392 7520 7648 7776 7904 8032 8160

6256 6384 6512 6640 6768 6896 7024 7152 7280 7408 7536 7664 7792 7920 8048 8176

1.2 Planning Principles

The allocation of downlink PSCs dose not affect the simulation of network planning. But

there are only 512 downlink PSCs for identifying intra-frequency cells, which are limited.

Therefore, it is necessary to consider the allocation of the downlink PSCs in the cell planning

procedure, as well as the factors of capacity expansion and coverage of the network in the future.

Based on this, all downlink PSCs will not be used in the initial stage of network planning, with

some reserved for future use. So we need to plan the downlink PSCs properly, and increase the

utilization of the code resource by means of code reuse.

In the cell PSC planning, we must conform to this principle: The intra-frequency cell

interfering to the primary cell cannot use the same cell PSCs as the primary cell. These cells

interfering to the primary cell are adjacent cells of the primary cell. Any cell may be a primary cell

with adjacent cells. Besides, neighboring cells exist in the adjacent cells of the primary cell. The

cell border is determined according to UE Rx level. In terms of primary cell, it can receive pilot



signals from other intra-frequency cells at the border of the cell. These pilot signals may be

stronger or weaker than that of UE access level. If the pilot signal at the border of the primary cell

is stronger than that of other cells, this cell is (or probably is) the neighboring cell of the primary

cell. And there is a soft handover area between two neighboring cells, which size is determined

by handover margin. For the pilot signals from other non-neighboring cells in the adjacent cells

received on the border of the primary cell, their strength is weaker than the access level of the

UE though, they generates interference to the receiver of the UE. So these cells cannot adopt

the same PSCs as the primary cell. On the other hand, the cells without interference to the

primary cell are regarded as non neighboring cells, which can use the same PSCs as this

primary cell.

1.3 Planning Method

The allocation of cell PSCs, a complicated procedure, can be performed with the

planning tool. This allocation procedure is quite similar to the frequency planning in GSM. But the

difference is, the cell PSC planning in WCDMA is not a key performance index (Refer to Section

4.5.2.4 of Reference [5]). The allocation of cell PSCs cannot guarantee a fast scrambling code

identification process of the UE, which is specified by the supplier. That is, no matter the PSCs of

the primary cell and those of the neighboring cell are allocated to the same scrambling code

group or not, the cell searching procedure of the UE will not be speeded up. This is related to the

realization of the UE. The UE should be able to find any PSC that is allocated by the network

side among the 512 PSCs.

So the cell PSCs can be planned in one of the following two methods:

Primary cell uses different PSCs from the neighboring cells, with the PSCs of the

primary cell and those of the neighboring cells belonging to the same scrambling code

group.

Primary cell uses different PSCs from the neighboring cells, with the PSCs of the

primary cell and those of the neighboring cells belonging to different scrambling code

groups.

Comparing these two methods, the former one requires less scrambling code groups,

and the PSCs in the scrambling code group can be allocated continuously, which is convenient

for reservation and manually planning, and it can also be applied for the automatic scrambling

code planner tool. It may probably simplify the cell searching procedure of the UE (related to the

scrambling code dependency matching strategy of the UE). So this method is recommended.

Please note that we only provide the planning ideas here. We do not strictly require that all the

cells use the eight scrambling codes of one scrambling group only. Actually, it is impossible to

100% ensure the PSCs of all cells allocated in the same scrambling code group. From the

automatic planner tool, we can see that when the code resource is restricted, the third step,



“Setting of the Minimize item in Filter”, will determine whether to add the number of scrambling

code groups or adding the number of scrambling codes in the scrambling code group, depending

on whether the cell PSCs are allocated continuously.

In the following chapters, you can learn the operation methods for Enterprise 4.0, the

network planner tool provided by AIRCOM, for performing the cell PSC planning automatically,

as well as the analysis on the planning result, the judging criteria and adjusting methods.

Moreover, the operation methods for manual planning of cell PSCs are provided. The parameter

description of each schematic diagram is only for the parameters involved in the scrambling code

planning only. Refer to Reference [3] for the setting of all the parameters.

2 Preparations for Applying Cell PSC Planner Tool

Before using the scrambling code planner tool for scrambling code planning, please

check the following items:

2.1 Checking PLMN Network Setup

Select the 3g->Database->Site menu as shown in the following window, and then

check whether a PLMN network exists, and whether BSs and cells have been set up in this

network. For the method for importing NodeB, refer to Reference [2].



Figure 1 PLMN

Description of the relevant parameters:

In the UMTS Parameters frame in the “Tab (Cell Params)” window:

Scrambling Code [0…7]: This specifies the PSCs used by the cell, ranging from 0

to 7.

Scrambling Code Group [0…63]: This specifies the scrambling code group of the

PSCs used by this cell, ranging from 0 to 63.

Note: If the PSCs of a cell do not need automatic planning, it can be designated directly in this

frame.

Scrambling Code Planning Parameters frame:

# of Code Groups in Neighbour Cells: It specifies the total number of the

scrambling code groups that this cell and its neighboring cells can use. It is a target value

for reference in the automatic planning. If it is set to 0, the item of #Code Group in the



cell PSC planning report automatically generated will be shown as N/A, indicating Not

Available, that means no constraint condition.

It specifies the total number of scrambling codes available in a scrambling code

group of this cell and the neighboring cell. It is a target value for reference in the

automatic planning. If it is set to 0, the item of #Code in the cell PSC planning

report automatically generated will be shown as N/A, indicating Not Available, that

means no constraint condition.

Note: If the PSCs of a cell and those of its neighboring cells are allocated to the same

scrambling code group, the parameter # of Code Groups in Neighbour Cells can be

set to 1, indicating this constraint condition will be taken into account in the automatic

planning.

2.2 Checking BS Setup and Cell Distribution on Map

Select the 3g->View->New 2D view menu, and select a map from the pull-down box

(note: If the terrain is not displayed, select the button <Show Data Types> and then <Clutter

Data> to configure the display elements). In following window check whether BSs and cells exist

in the map. (Note: the map is imported by setting the relevant contents of the coordinate system

and the maximum and minimum of the latitudes and longitudes of the map in the “Modify Project”

window. At the same time, the antenna data should also be imported. For detailed operation,

refer to Reference [4].



Figure 2 NodeBs&Cells

2.3 Checking whether 3g Carrier is Set up and Added to Cell

Select the 3g->Options->Carriers menu as shown in the following window, and check

whether 3g carriers have been configured or not, and then check whether the carriers have been

added to the cell, as shown in figure 3.



Figure 3 Carriers

2.4 Checking Cell Coverage Predictor

Select the 3g->Tools->Coverage Predictor menu to checking whether the cell

coverage has been created or not.

Figure 4 Coverage Predictor

3 Operation Process of Cell PSC Planner Tools

3.1 Setting Cell Range for Planning

Select the 3g->Database->Filters menu as shown in the following window, and add

Filter, and then set the cells to be allocated in this Filter.



Figure 5 Filters

3.2 Automatic Planning of Intra-carrier Neighboring Cells

Select the 3g->Tools->Neighbour Planner menu as shown in the following figure.

After selecting the cells to be planned and the Filters whether the neighboring cells of these cells

are located, set the relevant parameters as required to complete the automatic planning of

intra-frequency cells. If intra-carrier neighboring cells need to be considered in Step 2 of

automatic scrambling code planning in Section 3.4, this step is mandatory for getting the

neighboring cells for each cell.



Figure 6 Neighbour Planner

Description of relevant parameters:

Intra-Carrier Planning frame: Intra-carrier neighboring cell planning

Override Handover Margin [dB]: It indicates the pilot power difference between two

cells within the handover area should be smaller than or equal to the handover margin

value input here. This parameter is induced in the discussion on candidate cell for soft

handover. The bigger this parameter value, the larger the soft handover area, indicating

the soft handover connections will be increased. Thus more checks will be carried out for

a successful soft handover in the simulation procedure, and the average power value

between various cells in the activity set will be increased too. Hence, this parameter

should be set with consideration the soft handover overhead in the planning.

Carrier: It refers to the carrier used by the neighboring cell.

Resolution[m]: It is the resolution of the digital map as recommended.

Minimum Interfering Area [km2

]: It specifies the minimum interfering area between

the primary cell and a neighboring cell, indicating the interfering area between the primary

cell and the neighboring cells should be greater than this value. The primary cell may

have several soft handover areas meeting the requirement of Handover Margin, but

some soft handover area in the simulation is too small. This parameter can be used to

filter them.

Standard Deviation [dB]: It specifies the Eb/No standard deviation of the service

that the UE can accept, and it controls Eb/No distribution achieved by UE. When it is set

to 0, it indicates to ignore any deviation caused by power control. If the deviation caused



by power control must be considered, the Eb/No standard deviation of this service must

be set (other than 0).

Number of Neighbouring Cells: It refers to the maximum number of neighboring

cells that can be assigned to each cell.

3.3 Setting Schemas of Scrambling Code Group and

Scrambling Code

Select the 3g->Tools->Code Schemas menu, as shown in the following figure and

then set the scrambling code group and scrambling code resource.

Figure 7 Code Schemas

3.4 Run the UMTS Scrambling Code Planner Tool

Select the 3g->Tools->Scrambling Code planner menu, as shown in the following

figure and the click <Next>.



Figure 8 Scrambling code planner

3.4.1 Step 1

In the following figure select cells to be planned and the Filters where the neighboring

cells of these cells are located, and the click <Next>.

Figure 9 Scrambling code planner: step1

3.4.2 Step 2



In the following figure set the factors to be considered in the automatic planning, and

the click <Next>:



Neighbouring cells frame:

Consider Neighbouring cells: When it is selected, it indicates to consider the

distribution of the neighboring cell in the automatic planning.

Adjacent cells frame:

Consider Adjacent cells: When it is selected, it indicates to consider the distribution

of the adjacent cell in the automatic planning.

Max. # of adjacent cells: It refers to the maximum number of the adjacent cells with

different cell PSCs.

Code reuse distance frame:

Consider code reuse distance: When it is selected, it indicates to consider code

resource reuse in the automatic planning.

Min. code reuse distance (km): It indicates the cell range from the primary cell,

within which there is no identical cell PSCs.

Select carriers for planning frame: Selecting the carriers of the intra-carrier cell to

be planned.

Resolution (m): It is the resolution of the digital map as recommended.



Do not assign same code to cells under the same NodeB: When it is selected, it

indicates no cell under a NodeB use identical cell PSCs, no matter these cells are

in the same frequency or not.

3.4.3 Step 3

In the following figure select the code resource applied for the planning, and then other

constraint conditions, and click <Finish>.

Figure 11 Scrambling Code planner: step3


Description of the fields in the table above:

Filter: It lists the Filters requiring automatic scrambling code allocation.

State: Set the state of the current cell set to one of these three states: Planed

(indicating the automatic planner tool assigns these cell PSCs to the cells of these

Filters), Read-Only (indicating the automatic planner tool will not change the cell

PSCs in this Filter, even if collision occurs. And the Filter defined to this level will be

present in the report), and Ignore (indicating the automatic planner tool will not

consider the cells in the Filter of this level, and these cells will not be present in the

planning report either, so they will be ignored.). You can click the State column to

select one in the drop-down list box. If a cell belongs to two Filters at the same time,

you need to select its state from the Filter of the higher priority. The priority of a

Filter is determined according to its arrangement sequence, and can be adjusted

by means of the upward and downward buttons on the left in the window above.



#CodeGroups: This specifies the maximum number of scrambling code groups

used for a cell and its neighboring cells. It is valid for all the cells in the Filter. But it

should be optimized. It is taken as reference for the automatic planning which is

performed based on the neighboring cell list. If this value is null, the scrambling

code planner tool will adopt the number of scrambling code groups that can be

used by the neighboring cells of this cell designated in the cell parameter table in

Section 2.1.

#Codes: This specifies the maximum number of scrambling codes used for a cell

and its neighboring cells. It is valid for all the cells in the Filter. But it should be

optimized. It is taken as reference from the automatic planning of the neighboring

cell list. If this value is null, the scrambling code planner tool will use the number of

scrambling codes that can be used by the neighboring cells of this cell designated

in the cell parameter table in Section 2.1.

Minimize: In the automatic planning procedure, if the scrambling code groups and

scrambling codes to be used for a cell and its neighboring cell exceed the code

resource requirement on a Filter, the code planner tool will consider this item, that

is to minimize the number of scrambling codes or the number of scrambling code

groups. If this parameter is set to #Code, the automatic planner tool will increase

the number of scrambling code groups instead of the number of scrambling codes

in each group; if it is set to #CodeGroup, the automatic planner tool will increase

the number of scrambling codes in each group instead.

Code Schema: It indicates to select the code resource to be allocated in the

scrambling code planning, which is created in Section 3.3.

Cell Property button: To specify the number of special scrambling code groups and

scrambling codes for a cell, you can click this button to append parameters

conveniently. Note that if a cell belongs to two Filters, its state should be selected

from the Filter of the higher priority. This has been mentioned in the parameter of

State of Filter.

3.4.4 Step 4

The cell PSC planning report is generated as shown in the following figure. Analyze the

report. If the scrambling code group and scrambling code assigned to the cell meet the

requirements, click <Apply All Carriers> or <Apply Carrier> to complete the cell PSC planning.





Carrier Name: The automatic planner tool can assign cell PSCs to the intra-carrier

cell at different frequencies simultaneously. Here you can select different carriers

in the same window to browse the allocation result of the cell PSCs at this

frequency.

Apply All Carriers and Apply Carrier buttons: If you are satisfied with the allocation

result of PSCs in the pre-planning, you can click one of these two buttons to apply

the pre-planning result to the parameter setting of each cell.

Descriptions of the fields in the cell PSC table:

Cell name: List of intra-carrier cells at the selected frequency.



State: It indicates the PSCs of this cell is Planed (indicating the automatic planner tool

assigns these cell PSCs to the cells of these Filters) or Read-Only (indicating the

automatic planner tool will not change the cell PSCs in this Filter). In the planning, the

cell belonging to two Filters has higher priority, and will be planned first.

CodeGroup: It refers to the scrambling code group assigned by the scrambling

code planner tool.

Code: It refers to the scrambling code assigned by the scrambling code planner

tool.

Minimize: In the automatic planning procedure, if the scrambling code groups and

scrambling codes to be used for a cell and its neighboring cell exceed the code

resource requirement on a Filter, the code planner tool will consider this item, that

is to minimize the number of scrambling codes or the number of scrambling code

groups. If this parameter is set to #Code, the automatic planner tool will increase

the number of scrambling code groups instead of the number of scrambling codes

in each group; if it is set to #CodeGroup, the automatic planner tool will increase

the number of scrambling codes in each group instead.

#CG (Target): It is the number of scrambling code groups used designated the

neighboring cells only in the case the neighboring cells are considered in the

automatic planning, that is the value set in the cell properties in Section 2.1.

#CG (Achieved): It is the number of scrambling code groups actually used for the

neighboring cells after the planning only in the case that the neighboring cells are

considered in the automatic planning.

#C(Target): It is the number of scrambling codes designated for the neighboring

cells only in the case the neighboring cells are considered in the automatic

planning, that is the value set in the cell properties in Section 2.1.

#C(Achieved): It is the number of scrambling codes actually used for the

neighboring cells after the planning only in the case the neighboring cells are

considered in the automatic planning.

%Quality: It displays the interference percentage of the cells with identical

scrambling codes only in the case the adjacent cells are considered in the

automatic planning.

Relevant description of the scrambling code groups and scrambling codes of the

neighboring cells of the selected cell, the designated adjacent cells, all the cells nearby and other

cells under the NodeB:



Neighbours Cells: This specifies the scrambling code groups and scrambling

codes of the neighboring cells of the selected cell.

Adjacent Cells: This specifies the scrambling code groups and scrambling codes

of the designated adjacent cells of the selected cell.

Nearby Cells: This specifies the scrambling code groups and scrambling codes of

all the cells nearby.

NodeB Cells: This specifies the scrambling code groups and scrambling codes of

other cells under the NodeB.

4 Analysis on Cell PSC Planning

4.1 Analysis on Scrambling Code Planning Report Generated

Automatically

4.1.1 Setting of Relevant Parameters

It can be learnt from the parameters inputted in the operation process that the allocation

of cell PSCs by the automatic planner tool is related to such factors as the scrambling code

groups and scrambling codes that can be used, the number of neighboring cells, the scrambling

code reuse distance, resolution, and whether it is allowed to assign same code to cells under the

same NodeB. The following table shows the setting of the relevant parameters in the cell PSC

planning.

Table 2 The Parameters in scrambling code planner

Parameter name Value Setting description

Cell

Properties

# of Code Groups in Neighbour

Cells

0 No setting unless the number of the

scrambling code groups of the PSCs used for

the neighboring cells of a cell is restricted.

# of Codes in Neighbour Cells 0 No setting unless the total number of the

PSCs used for the neighboring cells of a cell is

restricted

Neighbouring

Cells

Planning

Override Handover Margin [dB] 3–6 It specifies the size of the handover area. If

the pilot of two cells is 3dB different from each

other, it can be set according to the proportion

of actual handover.

Resolution[m] X It is set to the resolution of the digital map.

Minimum Interfering Area[km2

] X It is the minimum value of the geographical

range of the actual handover area between



every two neighboring cells. It is to be set

according to the actual situation.

Standard Deviation [dB] 0 It refers to the Eb/No distribution of UE. When

it is set to 0, it indicates the Eb/No of the UE

reaches the target value, indicating the power

control deviation can be ignored.

Number of Neighbouring Cells 6 It indicates that each hexagon primary cell has

6 neighboring cells.

Scrambling

Code

Planning

Max. # of adjacent cells 6–18 It specifies the maximum number of adjacent

cells of each primary cell. It can be set to 6 for

hexagon cell, indicating all the adjacent cells

are neighboring cells.

Min. code reuse distance (km) X It is deducted with the formula 4.1.

Resolution (m) X It is the resolution of the digital map.

Filter

State Planed Only the Filter where the cell not to be planned

but for reference only will be set to ReadOnly

ro Ignored

#CodeGroups 1 This specifies that the PSCs of each cell and

its neighboring cells in this Filter are divided

into one scrambling code group. It can be

adjusted according to the scrambling code

resource.

#Codes 7 This specifies that the maximum number of

available PSCs of each cell and its

neighboring cells in this Filter is 7. It can be

adjusted according to the scrambling code

resource.

Minimize #CodeGroups

or #Code

If the above two items cannot be satisfied,

increase the number of available scrambling

codes in each scrambling code group or add

the number of scrambling code groups,

considering it is continuous allocation or not.

4.1.2 Adjustment Method

We can easily learn from the scrambling code report generated in Figure 12 that there

are many cells with clash codes with red mark. Such a code allocation result does not meet the

requirement. Here is the adjustment method:



First adjust the number of adjacent cells interfering to each other and the minimum

reuse distance to the optimal value. Here the number of adjacent cells is Max[The number of

adjacent cells interfering to each other of each cell]. It is adjusted within the range of (6–8). The

minimum reuse distance can be calculated according to the following the formula (4.1) (Refer to

Section 4.2 of Reference [5] for the formula deduction and analysis). If clash code still occurs,

you can also increase the available code resource, that is, to increase the value of K to achieve

the optimal effect.

KRD 3 ( 4.1 )

D is the minimum reuse distance, R stands for the minimum cell redius, and K is the

number of cell PSCs used. The above formula can be represented in the form of the formula

(4.2). Note: in the cell planning, we know the average cell radius, so we can roughly estimate the

minimum radius as: Average cell radius 70%.

ijjiK 2

...3210 ，，，， ji ( 4.2 )

The parameters i and j are the number of cells crossed in different directions within the

scrambling code distance. The range value of K is {1, 3, 4, 7, 9, 12…}.

For example, if 7 scrambling codes are used, and parameters i and j are 2 and 1

respectively, then the cell using the same PSCs as the primary cell is located at the point

crossing two cells toward south or other directions then crossing one cell after tuning o60

counterclockwise. Here the minimum reuse distance of scrambling codes is 4.58R. This

distribution law is shown in Figure 14 in the example of Section 4.13.

4.1.3 Example of Code Resource Reuse

The following is the planning of cell PSCs for the cells covered in Naijing City. We can

see from the generated scrambling code planning result that the scrambling code reuse is for

occupying the minimum code resource. For the 3 1 neighboring base stations distributed

equably, if the minimum reuse distance is ignored, that is to ensure only neighboring cells use

different PSCs, 7 PSCs are enough. However, adjacent cells interfering to each other must be

considered in practice. The following example is the maximum reuse allowed with the

consideration of the case that the primary cell has 8 adjacent cells interfering to each other:

Description of planning parameters: 1) there are totally 246 cells; 2) the code schema

designates three scrambling code groups of 0, 1 and 2, containing 24 scrambling codes in all.

But only 23 are used, which is enough; 3) the Max. # of adjacent cells is 8 and the Min. code

reuse distance (km) is 2 (The radius of the smallest cell). The numerals of X.X represent

scrambling code group and scrambling code respectively.



Figure 13 For example: NanJing Coverage



2.0

1.1

6

0.3

1.01.2

1.12.1 2.2

2.0

2.2

0.2

1.21.0

2.0

1.10.2

1.3

0.41.0

1.1

2.10.2

1.3

1.02.0

2.1

2.2

1.10.2

1.2

0.31.3

2.22.3

2.0

1.20.3

1.0

1.4

2.0

0.4

1.01.1

2.10.2

2.2

1.31.1

2.1

1.21.3 1.0

0.22.3

1.52.5 0.4

0.5

1.2

0.31.31.4

1.6

0.2

1.6

0.7

1.12.2

1.0

0.20.3

0.3

2.31.3

1.5

0.62.6

1.3

2.40.5

1.1

2.12.21.2

2.62.0

2.5

1.6

1.0

1.20.4

1.1

2.0

1.2

2.2

2.0

1.12.1

2.3

0.40.51.0

1.0

0.2

0.3

1.50.62.5

0.7 1.1

0.22.21.0

1.2

0.5

1.10.2

0.6

1.7

1.3

2.30.4

1.0

0.22.1

1.20.3

2.0

1.10.2

2.2

1.32.3

1.1

0.22.1

1.2

1.02.0

2.1

1.0

2.2

0.40.2

1.31.0

1.0

0.20.31.11.2

2.1

2.21.3

1.2

2.3

2.2

0.42.5

2.12.0

1.3

2.41.5

0.2

1.01.1

2.2

0.31.3

2.1

1.22.3

2.0

1.41.02.0

1.1

0.21.5

2.2

2.32.1

0.6

2.0

2.1

0.31.4

1.4

2.0

1.0

1.2

2.0

1.10.2

1.0

2.1

1.1

0.21.2

1.22.1

0.3

1.4

0.0

0.00.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.00.0

0.0

0.0

0.0

0.0

0.1

29

50

0

51

31

42

40

62

4143

3960

3759

46 38 44

21

58

45

6377

20

47

78

22

23 16 30

72

35

33

7324

15

11

65

67

3474 7

79

76

4

66

13

5

32

36

12

75 14

52

64

1

2

10

70

9

69

3

8

71

2581

2648

8049

27

17

28

54

68

53

55

56

57

19

18

61

2.4

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.10.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

Figure 14 For example: NanJing PSC Planning (CodeGroup.Code)

4.2 Analysis on Manual Configuration of Cell PSCs

4.2.1 Determining the Code Resource to be Used

When the number of cells to be planned is greater than or equal to 512, the maximum

number of available scrambling code resource is 64 scrambling code groups, each of which

contains 8 PSCs.



When the number of cells to be planned is less than 512, the maximum number of

available scrambling code resource is the number of cells to be planned.

In the manual planning, you need to estimate the minimum reuse distance according to

the neighboring cells and adjacent cells first, and then calculate the number of available PSCs

with the formula 4.1, as shown below:

2

2

3R

DK ( 4.3 )

To ensure the PSCs of all the neighboring cells in the same scrambling code group, you

should minimize the number of scrambling code groups as much as possible, preventing the

PSCs from being allocated to too many scrambling code groups.

4.2.2 Planning Method

It is recommended to use the area division method for the manual planning of cell PSCs,

for the cases of neighboring cells distributed equably and the remote cells without interference to

each other.

For the neighboring hexagon cells distributed equably, we can find this law from Figure

14 in Section 4.1.3: In the case that PSCs available to the neighboring hexagon cells distributed

equably with the consideration of only neighboring cells generate interference, that is, K being 7,

the parameters i and j are 2 and 1 respectively. Therefore, the cell using the same PSCs as the

primary cell is located at the point crossing two cells toward south or other directions then

crossing one cell after tuning o60 counterclockwise, as shown below. In this case, after defining

a cell cluster, you can allocate the PSCs repeatedly with the unit of this cell cluster. The values of

i and j calculated with the formula 4.2 vary with K.

0.4

0.5

0.3

0.6

0.2

0.00.1

0.4

0.5

0.3

0.6

0.2

0.00.1

Figure 15 Manual PSC Planning

For the remote cells without interference, the PSCs can be planned at will, as long as

no repetition with the neighboring cell.



4.3 Minimum Reuse Distance and Scrambling Code Resource

Reservation

Comparing with the limited frequency resource of the GSM, the 512 PSCs for

differentiating cells in WCDMS cell planning are relatively abundant. So the cell PSC planning

in 3G is not so strict as the frequency planning of GSM. But the reuse distance of the cell

PSCs still need to make the signals received by all the UEs meet the requirement of

carrier-to-interference ratio. That is, the adjacent cell with interference cannot use the same

PSCs as the primary cell. The minimum reuse distance is the distance from the primary cell to

the farthest adjacent cell. For the dense cells distributed equably, it is recommended to reuse

at least 12 PSCs (that is K is 12 and both i and j are 2.), then the minimum reuse distance can

be worked out with the formula 4.1, that is 6R, as shown below:

0.1

0.50.4

0.7

1.31.2

0.6

0.30.2

1.4

1.10.8 0.1

0.50.4

0.7

1.31.2

0.6

0.30.2

1.4

1.10.8

0.1

0.50.4

0.7

1.31.2

0.6

0.30.2

1.4

1.10.8

0.1

0.50.4

0.7

1.31.2

0.6

0.30.2

1.4

1.10.8

0.1

0.50.4

0.7

1.31.2

0.6

0.30.2

1.4

1.10.8

Figure 16 Minimize Reuse Distance

Generally, the scrambling code resource will not be used up, but will be reserved for the

future. As there is no experience for large-scale planning, we recommend reserving some

scrambling code resource according to the number of cells planned in the network construction

and the subsequent capacity expansion.



List of references:

[1] Wang Mingmin, WCDMA RNP Technology Research on Special Topics – Code Planning

Technology Research, 2002/08/23

[2] Yao Jianqing, WCDMA RNP ENTERPRISE V4.x Multi-Node Import Operation Guide,

2002/11/14

[3] Yao Jianqing, WCDMA RNP Technology Research on Special Topics -- ENTERPRISE

Parameter Analysis Report, 2003/01/04

[4] Chen Jing, WCDMA RNP ENTERPRISE V4.0 Planning Software Usage Guide V1.0,

2002/07/30

[5] Jens Zander, Seong-Lyun Kim, Radio Resource Management for Wireless Networks,

2001/06/30

[6] Jaana Laiho, Achim Wacher, Tomas Novosad, Radio Network Planning and Optimization for

UMTS, 2002

Documents

WCDMA RNP Cell Primary Scrambling Code Planning Guidance