07 omf007001 frequency planning issue1.4

8/8/2019 07 OMF007001 Frequency Planning ISSUE1.4

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OMF 007001

Frequency Planning

ISSUE1.4

OMF 007001

Frequency Planning

ISSUE1.4

Wireless Training Department


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contentcontent

Frequency planning

Tight frequency reuse

Frequency hopping


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Content of Frequency planningContent 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 1880

Duplex distance : 95 MHz

890 915 935 960

Duplex distance : 45 MHz

Frequency Resource of GSM SystemFrequency Resource of GSM System


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Frequency Band ConfigurationFrequency Band Configuration

GSM900:

BTS receiver (uplink ): f1 (n) =890.2+ (n-1)*0.2 MHz

BTS transmitter (downlink ): f2 (n) =f1 (n) +45 MHz

GSM1800:

BTS receiver (uplink ): f1 (n) =1710.2 + (n-512) * 0.2 MHz

BTS transmitter (downlink ): f2 (n) =f1 (n) +95 MHz


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All useful signals carrier

All useless signals interference=

GSM standard: C / I >= 9 dB

In practical projects: C / I >= 12dB

Useful signal Noise from environment

Other signals

Requirement for Interference and Carrier-

to-Interference Ratio


to-Interference Ratio

C/I =


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To-Interference Ratio


To-Interference Ratio

All useful signals carrier

All useless signals interference=

GSM standard: C / I >= 9 dB

In practical projects: C / I >= 12dB

Useful signal Noise from environment

Other signals

C/I =


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RXQUAL Mean BER BER rangeclass (%) from... to

0 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 QualitySignal 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 ReuseConcept of Frequency Reuse


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The Reason of Frequency ReuseThe 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 reuse

efficiency, but interference

is serious. More technique

Is needed.

Tighter reuse

0 10 20

Little interference, but frequency

reuse efficiency is low.

Reuse DensityReuse Density

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

4*312

n*mn*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 ReuseProblem of Frequency Reuse


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Interference (C/I) EstimationInterference (C/I) Estimation

6

1K

!

q

I

C

/

/R ( k )


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R

D

This old-fashioned frequency distribution

mode is not recommended

Frequency Reuse PatternsFrequency 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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A1

C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

A1

C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

A1

C1

B1D1

A2

A3 B2

B3

C2

C3

D2

D3 A1C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

A1

C1

B1 D1

A2

A3B2

B3

C2

C3

D2D3

A1

C1

B1D1

A2

A3B2

B3

C2

C3D2

D3

4*3 Frequency Reuse4*3 Frequency Reuse


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

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 of4*3

Frequency Reuse

Illustration of Frequency Allocation of4*3

Frequency Reuse


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OutlineOutline

Frequency planning


Frequency hopping


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Tight Frequency Reuse TechnologyTight Frequency Reuse Technology

Multi-layer reuse pattern

Underlaid and overlaid cell

1*3

1*1


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Multi-layer Reuse PatternMulti-layer Reuse Pattern


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BCCH: n1

TCH1: n2

TCH2: n3

~

TCHm-1: nm

n1n2n3 n4 ...... nm

And n1+n2+...+nm=n

Multi-layer Reuse PatternMulti-layer Reuse Pattern


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Multi-layer Reuse Pattern Frequency AllocationMulti-layer Reuse Pattern Frequency Allocation

Suppose that the available frequency carrier is 10MHZ,

channel number is 4694, the Multi-layer reuse pattern

should be:

typeAllocatedfrequencies

umber ofavailable

frequencies

H 46~ 1

H1 ~66 9

H 6 ~ 4

H ~

H4 ~ 6

H 9~94 6


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BCC H TCH1 TCH2 TCH3 TCH4

{f1,f3,f5...f23}

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

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

Multi-layer Reuse Pattern Frequency AllocationMulti-layer Reuse Pattern Frequency Allocation


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Capacity increase when reuse density is multiplied: Supposing there are 300 cells

Bandwidth: 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 NBW

re use

i

i

.!

Advantages of Multi-layer Reuse PatternAdvantages of Multi-layer Reuse Pattern


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The inner circle covers a smaller area, and the

frequency can be reused more tightly.

Underlaid/Overlaid Frequency AllocationUnderlaid/Overlaid Frequency Allocation

Overlaid-cellUnderlaid-cell


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Super fn

Regular fmRegular 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 ConfigurationOverlaid/Underlaid Frequency Configuration

Super fn


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BCCH14+TCH36

1BCCH+3TCH

1BCCH+3TCH 1BCCH+3TCH

1BCCH+12TCH

1BCCH+12TCH 1BCCH+12TCH

4*3 1*3

4*3 and 1*3 Reuse Patterns4*3 and 1*3 Reuse Patterns


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TRX1 TRX2 ... TRX7

TRX

8 TRX

9... TRX

14 TRX

15 TRX

16...TRX

21

TRX1 TRX2 ... TRX7

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

The red items are BCCH RCs

Illustration of1*3 TCH Frequency AllocationIllustration of1*3 TCH Frequency Allocation


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Frequency Planning PrincipleFrequency 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 PlanningExample of Frequency Planning


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Final frequency planning:

Example of Frequency PlanningExample of Frequency Planning


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Example of1*3 Frequency ReuseExample of1*3 Frequency Reuse

Suppose 900 band: 96124

BTS configuration: S3/3/3

BCCH layer: 96109 reuse pattern: 4*3

TCH layer: 110124 reuse pattern: 1*3


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

Group 2 (MA

2): 115 116 117 118 119 Cell2

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

TCHConsecutive Allocation SchemeTCHConsecutive Allocation Scheme


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TCH Interval Allocation SchemeTCH Interval Allocation Scheme

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

Group 2 (MA

2): 111 114 117 120 123 Cell2

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


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Comparison Between Multi-layer reuse and 1*3Comparison Between Multi-layer reuse and 1*3

For Multi-layer reuse pattern, either Base band hopping or RF

hopping can be used. But for 1x3 reuse, only RF hopping can be

used.

Multi-layer reuse pattern is a gradual process for TCH frequency

planning. In other words, the reuse is rather loose in TCH1 layer and

it is quite close in the last TCH layer (such as TCH5). The reason for

this pattern is that base band hopping is used in the Multi-layer reuse

pattern. When there are rather few frequency carriers, the hopping

gain is small. Therefore, more frequency carriers should be allocated

for the layer with small TCH and then the reuse coefficient is

relatively large. When RF hopping is used in the Multi-layer reuse

pattern and there are a large number of frequency carriers, the

hopping gain is high and the reuse coefficient can be very small. In

addition, the Multi-layer reuse pattern is of a free pattern. It is

different from base band hopping, in which the reuse must be loose

in the first TCH layer and more close in inner layers.


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Comparison Between Example of Frequency

Planning and 1*3

Comparison Between Example of Frequency

Planning and 1*3

The frequency planning for the 1x3 mode is simple and it is

easy 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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OverviewOverview

Frequency planning


Frequency hopping


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Content of Frequency HoppingContent of Frequency Hopping

Class of hopping

Advantages of hopping

Parameter of hopping

Collocation of hopping data


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FrequencyHoppingFrequencyHopping


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Class of HoppingClass of Hopping

Hopping can be implemented in two ways

Base-band hopping

RF hopping

Class according to the min hopping time

unit

Timeslot hopping

Frame hopping


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RF Hopping PrincipleRF Hopping Principle


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Class ofHoppingClass ofHopping

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 ofHoppingAdvantages ofHopping

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 and average the interference

Interference Diversity ofHoppingInterference Diversity ofHopping


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DescriptionHopping ParametersDescriptionHopping 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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DescriptionHopping ParametersDescriptionHopping 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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Description ofHopping ParametersDescription ofHopping Parameters

HSNhopping sequence number063.

HSN=0cycle hopping.

HSN0 random hopping. Every sequence number

corresponds a pseudo random sequence.


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Hopping ParametersHopping Parameters

Hopping mode: the mode used by the BTS system, including

three options: not hopping, base band hopping and RF

hopping.

CA (Cell Allocation Table): refer to all available frequencycarriers in the cell. The allocation should be consecutive

starting from the effective frequency carrier 0. There should be

no empty data item. The frequency carrier configuration

should be in an ascending order.


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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 CellA

llocation Table, and no frequency of BCCH channel should be in the set.

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

for hopping. 0 stands for sequence hopping and other values

for pseudo random sequence hopping.


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MAIO (Mobile Allocation Index Offset): used to define the

initial frequency of the hopping.

The MAIO of all channels of one hopping TRX must be

identical. The MAIO of channels of different hopping TRX in

the same cell must be different.

TSC (Training Sequence Code): used for delay equalization at

the receiver end. TSC must be the same as the BTS color

code. When an MS or BTS receives signals, delay

equalization is started with the specified TSC. But for the co-

channel signals with different TSC, delay equalization is

impossible, so that demodulation can not be received. In this

way, erroneous receiving is prevented effectively and then co-

channel interference is prevented.


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Note: means absolutely same; means absolutely different;

# means uncertain.

Hopping Data Configuration RulesHopping Data Configuration Rules

TSC CA MA HSN MAIO

The same RC

in the cell

Different RC

in the cell

Co-channel

cell

#


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07 omf007001 frequency planning issue1.4

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