008 WCDMA Primary Scrambling Code Planning

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WCDMA Primary Scrambling Code Planning

ISSUE 1.0


object

Upon completion this course, you will be

able to:

� Understand the principles for cell primary

scrambling codes allocation in the WCDMA

network

� Understand how to plan the cell primary

scrambling codes (PSC)

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ChapterChapter 1 1 WCDMA PSCs

Chapter 2 WCDMA PSC planning principle

Chapter 3 WCDMA PSC planning method

Chapter 4 WCDMA PSC planning case

HUAWEI TECHNOLOGIES CO., LTD. Page 3All rights reserved

� Scrambling code ：GOLD sequence.

� Scrambling code period : 10ms ,or 38400 chips.

� The codes used for scrambling of the uplink physical channels may be of

either long or short type, There are 224 long and 224 short uplink scrambling

codes. Uplink scrambling codes are assigned by higher layers. Due to a

great quantity of uplink scrambling codes is exist and uplink scrambling

codes is allocated by RNC, so we are not give it our attention.

� For downlink physical channels, a total of 218-1 = 262,143 scrambling codes

can be generated. scrambling codes k = 0, 1, …, 8191 are 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). The 512 PSCs are also divided into 64 groups, each of which

contains 8 PSCs. Downlink PSC is used to distinguish the different cells. So

we will give it our attention In RNP.

WCDMA Scrambling CodesWCDMA Scrambling Codes

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Scrambling

codes for downlink physical channels

Set 0

Set 1

…

Set 511

Primary scrambling code 0

……

Secondary scrambling code 1

Secondary scrambling code

15

Primary scrambling code

511××××16

……

Secondary scrambling code

511××××16＋＋＋＋15

8192 scrambling

codes512 sets

A primary scrambling code and 15 secondary scrambling codes are included in a set.

Downlink Scrambling CodesDownlink Scrambling Codes


Group 0

Group 1

…

Group 63

512 primary scrambling codes

64 primary scrambling code groups

Each group consists of 8 primary scrambling codes

Downlink Primary Scrambling Code GroupsDownlink Primary Scrambling Code Groups

Primary scrambling codes for downlink

physical channels


……




8*63

……


63*8＋＋＋＋7

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Downlink Primary Scrambling Codes

203219041776164815201392126411361008880752624496368240112PSC_8

2016188817601632150413761248112099286473660848035222496PSC_7

2000187217441616148813601232110497684872059246433620880PSC_6

1984185617281600147213441216108896083270457644832019264PSC_5

1968184017121584145613281200107294481668856043230417648PSC_4

1952182416961568144013121184105692880067254441628816032PSC_3

1936180816801552142412961168104091278465652840027214416PSC_2

192017921664153614081280115210248967686405123842561280PSC_1

1514131211109876543210

主主主主扰扰扰扰码码码码/组组组组

4080395238243696356834403312318430562928280026722544241622882160

4064393638083680355234243296316830402912278426562528240022722144

4048392037923664353634083280315230242896276826402512238422562128

4032390437763648352033923264313630082880275226242496236822402112

4016388837603632350433763248312029922864273626082480235222242096

4000387237443616348833603232310429762848272025922464233622082080

3984385637283600347233443216308829602832270425762448232021922064

3968384037123584345633283200307229442816268825602432230421762048

31302928272625242322212019181716


Downlink Primary Scrambling Codes

6128600058725744561654885360523251044976484847204592446443364208

6112598458565728560054725344521650884960483247044576444843204192

6096596858405712558454565328520050724944481646884560443243044176

6080595258245696556854405312518450564928480046724544441642884160

6064593658085680555254245296516850404912478446564528440042724144

6048592057925664553654085280515250244896476846404512438442564128

6032590457765648552053925264513650084880475246244496436842404112

6016588857605632550453765248512049924864473646084480435242244096

47464544434241403938373635343332

8176804879207792766475367408728071527024689667686640651263846256

8160803279047776764875207392726471367008688067526624649663686240

8144801678887760763275047376724871206992686467366608648063526224

8128800078727744761674887360723271046976684867206592646463366208

8112798478567728760074727344721670886960683267046576644863206192

8096796878407712758474567328720070726944681666886560643263046176

8080795278247696756874407312718470566928680066726544641662886160

8064793678087680755274247296716870406912678466566528640062726144

63626160595857565554535251504948

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Principle ：：：：

The intra-frequency cells interfering to the

primary cell cannot use the same cell PSCs

as the primary cell !

Which cells are included in the intra-frequency

cells interfering to the primary cell?

- Adjacent cell

- Neighboring cell

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� What is adjacent 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.

� What is neighboring cell ?

− Besides, neighboring cells exist in the adjacent cells of the primary

cell. 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 UE

access level, this cell is (or probably is) the neighboring cell of the

primary cell.


WCDMA PSCs planning principle

�What is non neighboring cell ?

− These cells without interference to the primary cell are

regarded as non neighboring cells, which can use the same

PSCs as this primary cell.

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WCDMA PSC planning method� 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.

� NOW THE LATER IS RECOMMENDED

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� In general, there is less 4 intra-cells in a site in actual network.

So we can divide a group (8 PSCs every group) to 2 subgroups

(4 PSCs every subgroup).

� 512 PSCs can divide 128 subgroups. The first PSC every

subgroup take part in the PSC allocation ,the other PSCs are

allocated the same cell.

� We must remain partially PSCs in order to network evolution.

(for example next figure gray PSCs will be remained .)

WCDMA PSC planning caseWCDMA PSC planning case

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WCDMA PSC planning case



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WCDMA PSC planning case�0# PSC is allocated site 0,so 1,2,3# PSC is allocated site

0,too

� If site 0 has three cells, then allocate three 0,1,2#PSC to

three cells and 3# PSC is remained to add a new cell.

�we recommend to use the remained PSC when add a new

cell

� In each cluster there are 16 column of scrambling codes

� In each column there are 4 codes which belong to one code

group, so they can be used for one site if the sector number of

the site is less or equal than 4

� Normally we use 12 columns in each sub-cluster, and the back 4

columns (grey ones) are reserved for future use, such as

capacity expansion or problem solve

� Cluster 1-7 are used for outdoor sites, cluster 8 is used for

indoor sites

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416424432288296304

408384440280256312

400392448272264320

472464456344336328

160168176324048

15212818424056

14413619216864

216208200888072



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D=12r

D=14r



D=12r

D=15.2r

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D=14r

D=13.4r


WCDMA PSC planning case� Scheme (1): The min reuse distance is 12r, the max reuse distance is 14r,

r is the cell radius

� Scheme (2): The min reuse distance is 12r, the max reuse distance is

15.2r

� Scheme (3): The min reuse distance is 13.4r, the max reuse distance is

14r

� With comparing we can see scheme (2) and (3) are better than (1)

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008 WCDMA Primary Scrambling Code Planning

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