OMF007001 Frequency Planning ISSUE1.4

8/13/2019 OMF007001 Frequency Planning ISSUE1.4

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Content of Frequency planning

Frequency resource of GSM system

Requirement for interference and carrier-to-

interference ratio

Signal quality grade coding

Concept of frequency reuse

4*3 frequency reuse


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GSM 900 :

GSM 1800 : 1710 1785 1805 1880Duplex distance : 95 MHz

890 915 935 960

Duplex distance : 45 MHz

Frequency Resource of GSM System


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All useful signals carrier All useless signals interference =

GSM standard: C / I >= 9 dBIn practical projects: C / I >= 12dB

Useful signal Noise from environment

Other signals

Requirement for Interference and Carrier-to-Interference Ratio

C/I =


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Requirement for Interference and Carrier-To-Interference Ratio

All useful signals carrier All useless signals interference =

GSM standard: C / I >= 9 dBIn practical projects: C / I >= 12dB

Useful signal Noise from environment

Other signals

C/I =


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Effect of Interference

Decrease of signal quality

Bit error

Recoverable: channel coding, error correction

Irrecoverable: phase distortion

System interference model

Unbalanced: uplink interference downlink interference

Asymmetrical: the interference is different at the MS and BTS ends


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RXQUAL Mean BER BER rangeclass (%) from... to0 0.14 < 0.2%1 0.28 0.2 ... 0.4 %2 0.57 0.4 ... 0.8 %3 1.13 0.8 ... 1.6 %4 2.26 1.6 ... 3.2 %5 4.53 3.2 ... 6.4 %6 9.05 6.4 ... 12.8 %7 18.1 > 12.8 %

Fairly good

Intolerable

Good

Acceptable

Signal Quality

Receiving quality (RXQUAL parameter)

Level of receiving quality (0 ... 7)

Bit error rate before decoding and error correction


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{fi,fj..fk}

{fi,fj..fk} {fi,fj..fk} {fi,fj..fk} .. ..

Macro-cell system

d Micro-cell system

Concept of Frequency Reuse


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The Reason of Frequency Reuse

Frequency resource is limited. If there is 8MHz frequency

resource, 8 MHz = 40 channels * 8 timeslots = 320

==> max. 320 users can access the network at the same

time.


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Looser reuse

Higher frequency reuseefficiency, but interference

is serious. More technique

Is needed.

Tighter reuse

0 10 20

Little interference, but frequency

reuse efficiency is low.

Reuse Density

Reuse density is the number of cells in a basic reuse cluster.

4*3 12

n*m n*m

n: BTS number in a basic reuse cluster

m: Frequency group number in a BTS


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[fn]

[fn]

D

[fn]

R

Reuse of a frequency causes the co-channel interference

Problem of Frequency Reuse


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Interference (C/I) Estimation

6

1 q

I

C /q= /(


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R

D

This old-fashioned frequency distributionmode is not recommended

Frequency Reuse Patterns

Purpose: to minimize the interference in the whole network with

the final frequency allocation plan

Theoretically

Regular hexagon cell

Regular network distribution

Cell cluster

Multiplexing distance

D = R *sqrt(3*K)


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A1C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

A1C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

A1C1

B1

D1A2

A3B2

B3

C2

C3D2

D3 A1C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

A1C1

B1D1

A2

A3B2

B3

C2

C3

D2D3

A1C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

4*3 Frequency Reuse


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A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3

34 34 35 36 37 38 39

40 41 42 43 44 45 46 47 48 49 50 51

52 53 54 55 56 57 58 59 60 61 62 63

64 65 66 67 68 69 70 71 72 73 74 75

76 77 78 79 80 81 82 83 84 85 86 87

88 89 90 91 92 93 94 95

Illustration of Frequency Allocation of 4*3Frequency Reuse


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Outline

Frequency planning

Tight frequency reuse

Frequency hopping


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Tight Frequency Reuse Technology

Multi-layer reuse pattern

Underlaid and overlaid cell

1*3

1*1


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Multi-layer Reuse Pattern


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BCCH: n1

TCH1: n2

TCH2: n3

TCHm-1: n m

n1 n2 n3 n4 ...... n m

And n1+n2+...+n m =n

Multi-layer Reuse Pattern


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Multi-layer Reuse Pattern Frequency Allocation

Suppose that the available frequency carrier is 10MHZ,

channel number is 46 94, the Multi-layer reuse pattern

should be:

RC type AllocatedfrequenciesNumber ofavailable

frequencies

BCCH 46~57 12

TCH1 58~66 9

TCH2 67~74 8TCH3 75~82 8

TCH4 83~88 6

TCH5 89~94 6


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BCCH TCH1 TCH2 TCH3 TCH4

{f1,f3,f5...f23}

{f1,f2,f3,f4,f5...f40}

{f2,f4..f22,f24...f40}

Multi-layer Reuse Pattern Frequency Allocation


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Capacity increase when reuse density is multiplied:Supposing there are 300 cellsBandwidth: 8 MHz (40 frequency)

Normal 4*3 reuse: reuse density=12 ==> network capacity = 40/12 * 300 = 1000TRX

Multiple reuse:BCCH layer: re-use =14, (14 frq.)Normal TCH layer: re-use =10, (20 frq.)

Aggressive TCH layer:re-use = 6, (6 frq.) ==> Network capacity = (1 +2 +1)* 300 =1200 TRX

cap N BW re use

i

i

.

Advantages of Multi-layer Reuse Pattern


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Capacity increases when reuse density is multiplied:Supposing there are 300 cellsBandwidth: 8 MHz (40 frequency)

Normal 4*3 reuse: reuse density=12 ==> network capacity = 40/12 * 300 = 1000TRX

Multiple reuse:BCCH layer: re-use =14, (14 frq.)Normal TCH layer: re-use =10, (20 frq.)

Aggressive TCH layer:re-use = 6, (6 frq.) ==> Network capacity = (1 +2 +1)* 300 =1200 TRX

cap N BW re use

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Advantages of Multi-layer Reuse Pattern


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The inner circle covers a smaller area, and thefrequency can be reused more tightly.

Underlaid/Overlaid Frequency Allocation

Overlaid-cell Underlaid-cell


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Super fn

Regular fm Regular fm

Regular fm

Super fn

BCCH 15f Regular 24f Super 12f

BCCH Reuse density: 15

R TCH TRX reuse density: 12

S TCH TRX reuse density: 6

Overlaid/Underlaid Frequency Configuration

Super fn


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TRX1 TRX2 ... TRX7

TRX8 TRX9... TRX14 TRX15 TRX16...TRX21

TRX1 TRX2 ... TRX7

TRX8 TRX9... TRX14 TRX15 TRX16...TRX21

The red items are BCCH RCs

Illustration of 1*3 TCH Frequency Allocation


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Frequency Planning Principle

There should be no co-channel frequency carriers in one BTS.The frequency separation between BCCH and TCH in the same cell

should be not less than 400K.

When frequency hopping is not used, the separation of TCH in the

same cell should be not less than 400K.In non-1*3 reuse mode, co-channel should be avoided between the

immediately neighbor BTS.

Neighbor BTS should not have co-channels facing each other directly.

Normally, with 1*3 reuse, the number of the hopping frequencies

should be not less than twice of the number of frequency hopping

TRX in the same cell.

Pay close attention to co-channel reuse, avoiding the situation that

the same BCCH has the same BSIC in adjacent area.


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An example network in a specific place, BTS are densely located.

The topography is plain. The maximum BTS configuration is S3/3/2.Initial planning:

Example of Frequency Planning


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Final frequency planning:

Example of Frequency Planning


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Example of 1*3 Frequency Reuse

Suppose 900 band: 96 124

BTS configuration: S3/3/3

BCCH layer: 96 109 reuse pattern: 4*3

TCH layer: 110 124 reuse pattern: 1*3


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Group 1 (MA1): 110 111 112 113 114 Cell1

Group 2 (MA2): 115 116 117 118 119 Cell2

Group 3 (MA3): 120 121 122 123 124 Cell3

TCH Consecutive Allocation Scheme


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TCH Interval Allocation Scheme

Group 1 (MA1): 110 113 116 119 122 Cell1

Group 2 (MA2): 111 114 117 120 123 Cell2

Group 3 (MA3): 112 115 118 121 124 Cell3


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Comparison Between Example of FrequencyPlanning and 1*3

The frequency planning for the 1x3 mode is simple and it iseasy to plan the frequency for new added BTS.

1x3 mode requires a rather regular BTS location distribution.

For the cells with fixed number of TRX, when the traffic is

heavy, the 1x3 provides higher service quality than that of

Multi-layer reuse pattern.

TRX can be easily added to the 1x3 network, but TRX number

of hopping should not exceed the product of the allocatedhopping frequency number and the max RF load ratio.

BCCH of Multi-layer reuse pattern can take part in the

frequency hopping, while BCCH in 1x3 mode can not.


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Content of Frequency Hopping

Class of hopping

Advantages of hoppingParameter of hopping

Collocation of hopping data


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Class of Hopping

Hopping can be implemented in two waysBase-band hoppingRF hopping

Class according to the min hopping time

unitTimeslot hoppingFrame hopping


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Base Band Hopping Principle


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RF Hopping Principle


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Class of Hopping

Frame hopping

Frequency changes every TDMA frame. The different channel

of one TRX uses the same MAIO.

Timeslot hopping

Frequency changes every timeslot. The different channel of one

TRX uses the different MAIO.


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Advantages of Hopping

Get an agreeable radio environment.

Provide a similar communication quality for every user.

Tighter reuse patterns are possible to be used for larger

capacity.


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Smoothen the rapid fading (Rayleigh fading)

Frequency Diversity of Hopping


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Description Hopping Parameters

At the Um interface, the ARFCN on a specific burst is an

element in MA set. MAI is used for indication, referring to a

specific element in the MA set.

When 0< MAI


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Description Hopping Parameters

At the air interface, the RC number on a specific burst is an

element in MA set. MAI is used for indication, referring to a

specific element in the MA set.

When 0< MAI


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Hopping Parameters

MA (Mobile Allocation Set): the set of available RF bands

when hopping, containing at most 16 frequency carriers. The

frequency being used must be those of the corresponding cell

number in Cell Allocation Table , and no frequency of

BCCH channel should be in the set.

Location: in Carrier Configuration Table .

HSN (Hopping Serial Number): used to define the actual rule

for hopping. 0 stands for sequence hopping and other valuesfor pseudo random sequence hopping.

Location: in Frequency Hopping Table .


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Note: means absolutely same; means absolutely different;

# means uncertain.

Hopping Data Configuration Rules

TSC CA MA HSN MAIO

The same RCin the cell

Different RCin the cell

Co-channelcell #


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Description of Cell Allocation Table

Field name Meaning Value range Suggestion

Module ID Module ID is the number of the modulecontaining the cell

0~255

Cell ID Cell ID is the index value of the cell 0~65535

Cell name It is just a prompt 30 bit

ARFCN 0~63 It is used to configure the ab solute RC numberin the cell using frequency bands; each cell canbe configured with at most 64 frequency bands.The number of frequency bands to be used inpractice is usually determined in networkplanning.When there are less than 64 frequency bands,the invalid field need no configuration. Forexample, if only 6 bands are used, effective

bands 0~5 should be configured and thesubsequent effective bands 6~63 should not beconfigured.

M900:

1~124;M1800:

512~885

Configureas

necessar y


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Field Name Meaning Value range Suggestion

Module ID Module ID is the number of the modulecontaining the cell 0~255Cell ID Cell ID is the index value of the cell 0~65535

HW-IUOproperty

Indicating whether TRX should be configuredas OverLaid or UnderLaid subcell.

equipmentgroup ID

The number of the equipment group at thesite. One site supports at most 3 equipmentgroups; It is usually configured as 0 at

present.

0~2 0

ARFCN

Configure the frequency that the RC unitoccupies. Configure one frequency when thereis no hopping. If hopping is necessary,configure 3~64 bands. These effective RCsmust be the subset of the effective RCs in thecell distribution table.

The subsetof the

effective RCin Cell

AllocationTable

Static TRXPower classl

Static transmitting power level of the RC. 0corresponds to the static power 46dBm, i.e.40W. The static power is lowered by 2dB withthe level goes up by 1.

0~13 Subject toactual

conditionand the

equipmentcapacity

Description of RC Configuration Table


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Fieldname

Meaning Value range Suggestion

FH indexnumber

The index number of all sorts of hoppingstatus, providing index value for RadioChannel Configuration Table . The numbersare in a sequence starting from 0.

0~255

HSN

HSN, indicating the sequence rule of thehopping. Usually, there is only one HSN in

the same cell and the HSN in the co-channel

cell must be different. The above-mentionedrules must be observed.

0~63

TSC

Decide the parameters of the self-adaptiveequalization filter in the receiving processing

filter. It is the same as the correspondingbase color code (BCC).

0~7

FH ARFCN

Number of frequency in the hopping serial. According to hopping algorithm, at least 3

frequencies are required for hopping gain. Ifthis field is left blank, it is invalid.

Correspondingparticipant hopping

frequency in CellConfiguration DataTable

Configure as

necessary

Description of Hopping Data Table


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Domain name Meaning Value range Suggestion

TRX ID The number of TRX unit in an BS 0~24

Channel ID Number of physical timeslot in TRX 0~7

Ch type Logic channel type of timeslots, includingTCH Full Rate, TCH Half Rate 01, TCHHalf Rate 0, SDCCH8 , Master BCCH,Composite BCCH, BCH, BCCH + CBCH,

SDCCH + CBCH, etc.

9 channelgroupings

FH indexnumber

It is used to index to corresponding record inHopping Data Table .

0~255

MAIO MAIO, used to decide initial frequency offsetof the hopping.

Less thanthe numberof hoppingfrequency

Sub-ch ID One timeslot is divided into 2 sub- channel 0,1at half rate. It is all 0 at full rate. 0~1

circ uit number Number of trunk circuit at Abis interfaceoccupied by the corresponding physicaltimeslot.

0~65535

Description of Radio Channel Configuration Table


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Documents

OMF007001 Frequency Planning ISSUE1.4