frequency planning_wright.ppt

8/10/2019 Frequency Planning_Wright.ppt

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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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Frequency Planning&

Neighbor Cell PlanningISSUE1.0


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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2

Chapter 1 Basic knowledge

Chapter 2 Frequency planning

Chapter 3 Frequency hopping

Chapter 4 Neighbor Cell Planning


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Content of Basic knowledge

Frequency resource of GSM system

Requirement for carrier-to-interference ratio

Signal quality grade coding


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Channel Interval 200kHz

1710 1785 1805 1880

Duplex distance : 95 MHz

890 915 935 960

Duplex distance : 45 MHz

GSM 900 :

GSM 1800 :

Frequency Resource of GSM System


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Frequency Band Configuration

GSM900

BTS receiver (uplink ): f1 n 890 n0.2 MHz

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

GSM1800

BTS receiver (uplink ): f1 n 1710 n 511 0.2 MHz

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


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Requirement for Carrier-To-Interference Ratio

All useful signals carrier All useless signals interference =

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

Useful signal Noise from environment

Other signals

C/I =


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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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Question1If ARFCN is 96,

what is the corresponding frequency value?

If the frequency value is 909.8M in uplink,

what is the corresponding channel number?

If ARFCN is 128

which band does it belong to, GSM900 or 1800 or neither?

If the frequency resource is 6M,

how many channels are there?

if no frequency reuse, how many subscribers can access

network at the same time?


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Chapter 4 Neighbor Cell Planning


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2.1 Concept of frequency reuse

2.2 Normal frequency reuse

2.3 Tight frequency reuse


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Concept of Frequency Reuse

{fi,fj..fk} Macro-cell system

Micro-cell system

d

reuse

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

reuse


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The Reason of Frequency Reuse

Frequency resource is limited. If there is 8MHz frequency resource,

Case 1:No frequency reuse

8 MHz = 40 channels * 8 timeslots = 320==> max. 320 users can access the network at the same time.

Case 2:Frequency reuse

If each frequency carrier is reused for n times, then 320*n users can

communicate at the same time. (The actual relation is more than ntimes.)


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Frequency Reuse induce Co-channel interference

Problem of Frequency Reuse

1/2

q = D/R = ( 3 k )

6

q I C

fnfn

fnfn

fn

fnfn

RD

Interference coming from 6 co-channel cells

At the cell boundary, the interference issevere

6)1(

q I C


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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 DensityReuse density is the number of cells in a basic reusecluster.

4*3 12

n*m n*m

n: BTS number in a basic reuse cluster

m: Frequency group number in a BTS

12


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Capability

Quality InterferenceBit error

Limited by

Balance

Frequency resource Frequency reuse


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4*3 Frequency Reuse

A1C1

B1

D1A2

A3B2

B3

C2

C3D2

D3

A1C1

B1

D1A2

A3B2

B3

C2

C3D2

D3

A1

C1

B1

D1A2

A3

B2

B3

C2

C3D2

D3 A1 C1

B1

D1A2

A3B2

B3

C2

C3D2

D3

A1C1

B1D1A2

A3B2

B3

C2

C3D2

D3

A1 C1

B1

D1A2

A3B2

B3

C2

C3D2

D3

4 BTS3 cells/BTS12 cells constructa cluster


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Illustration of Frequency Allocation of 4*3

Frequency Reuse

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


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4*3 frequency use

A1 C1

B1

D1A2

A3B2

B3

C2

C3D2

D3

A1C1

B1

D1A2

A3B2

B3

C2

C3D2

D3

A1

C1

B1

D1A2

A3

B2B3

C2

C3D2

D340

42

41

4344

3645

37

34

3835

39A1

C1

B1D1A2

A3B2

B3

C2

C3 D2

D3

A1C1

B1

D1A2

A3B2

B3

C2C3

D2

A1

C1

B1

D1A2

A3B2

B3

C2

C3D2

D3D3

5254

5355

56

4857

49

4650

47

51

4*3 is normal frequency useBCCH planning must use 4*3


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Tight Frequency Reuse Technology

1 Multi-layer reuse pattern (MRP)

2 1*3

3 1*1

4 Underlaid and overlaid cell


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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 ...... nm

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

Multi-layer Reuse Pattern


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Multi-layer Reuse Pattern Consecutive Frequency Allocation

Suppose that the available frequency carrier is 10MHZ,channel number is 46 77, the Multi-layer reuse patternshould be:

RC type AllocatedfrequenciesNumber ofavailable

frequencies

BCCH 46~57 12

TCH1 58~66 9

TCH2 67~72 6

TCH3 73~77 5


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1

2

3

4

2

2 2

3

3

3

4 4

2

2

2Layou t


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1

2

3

4

2

2 2

3

3

3

4 4

2

2

2

BCCH


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1

2

3

4

2

2 2

3

3

3

4 4

2

2

2

TCH Layer 1


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1

2

3

4

2

2 2

3

3

3

4 4

2

2

2

TCH Layer 2


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1

2

3

4

2

2 2

3

3

3

4 4

2

2

2

TCH Layer 3


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Multi-layer Reuse Pattern -Interval Frequency Allocation

BCCH TCH1 TCH2 TCH3 TCH4

{f1,f3,f5...f23}

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

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


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cap N BW re use

i

i

.

Advantages of Multi-layer Reuse Pattern

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 = 1000 TRX

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


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1*3 frequency reuse

Cell configuration is advanced with the samefrequency resource

Cell Radius is the same Reuse distance isdecreased, Interference is enhanced.

We need use extra technology to resistinterference while using 1*3 frequency reuse

1*3 D

R

4*3 D

R

Compare 1*3 frequency reuse with 4*3 reuse


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General Underlay Overlay

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

Overlay-cell Underlay-cell

Overlay-cell Underlay-cell

D

rR


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BCCH 15f Regular 24f Super 12f

BCCH Reuse density: 15

R TCH TRX reuse density: 12

S TCH TRX reuse density: 6

Intelligent Underlay Overlay

Super fn

Regular fm

Regular fm

Super fnSuper fn


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Chapter 4 Neighbor cell planning


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3.1 Advantage and class of hopping

3.2 Hopping parameter

3.3 Hopping application


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Frequency hopping refers to the regular hopping of

carrier frequency within certain range

Concept of Frequency Hopping

Bn || fnBn-1 || fn-1

B1 || f1

BURST


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Advantages of Hopping

B4 B3 B2 B1f4 f3 f2 f1

f4f3f2

f1

Hopping is a special frequency diversity

Get an agreeable radioenvironment.

Provide a similar

communication quality forevery user .

Tighter reuse patternsare possible to be usedfor larger capacity

f1

f1


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Class of Hopping

Class according to the way of implementationBase-band hopping

RF hopping

Class according to the min hopping time unit

Timeslot hopping

Frequency changes every timeslot.

Frame hopping

Frequency changes every TDMA frame.


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Base Band Hopping Principle


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RF Hopping Principle


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Hopping Parameters Wh ?


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Hopping ParametersHopping mode : the mode used by the BTS system, including three options: not

hopping, base band hopping and RF hopping.

MA (Mobile Allocation Set): the set of available frequency when hopping,

containing at most 64 frequency carriers. The frequency being used must be those

of the available frequency

HSN hopping sequence number 0 63 . HSN=0 cycle hopping,HSN0

random hopping. Every sequence number corresponds a pseudo random

sequence.

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

hopping.

TSC : should be set consistent with BCC

What ?


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Hopping Parameters

All the parameters which are related to hopping are configured

in cell/configure Hopping data

Where ?


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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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TCH Consecutive Allocation Scheme

MAIO

MA1 110 111 112 113 114 0,2

MA2 115 116 117 118 119 0,2

MA3 120 121 122 123 124 0,2

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3


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TCH Interval Allocation Scheme

MAIOMA1 110 113 116 119 122 0,2,4

MA2 111 114 117 120 123 1,3

MA3 112 115 118 121 124 0,2

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3


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Compare two Allocation Scheme

Different MA value Different MAIO value

Under 6MHz band Consecutive Allocation support

max site type S3/3/3 theoretically while Interval Allocation support max type S4/3/3

Consecutive Allocation is usually used in urban area,While Interval allocation is usually used in town andcountry.

In order to decrease the inference between differentBTS, It is better to keep the cell azimuth consistent


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Comparison Between Multi-layer reuse and 1*3

For Multi-layer reuse pattern, either Base band hopping or RF hoppingcan be used. But for 1x3 reuse, only RF hopping can be used.

The frequency planning for the 1x3 mode is simple and it is easy to planthe 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 1x3provides 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 allocated hopping frequencynumber 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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Frequency Planning PrincipleThere should be no co-channel frequency carriers in one BTS.

The frequency separation between BCCH and TCH in the same cell shouldbe not less than 400K.

When frequency hopping is not used, the separation of TCH in the samecell should be not less than 400K.

In non-1*3 reuse mode, co-channel should be avoided between theimmediately 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 samecell.

Pay close attention to co-channel reuse, avoiding the situation that thesame BCCH has the same BSIC in adjacent area.

Example of Frequency Planning


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.

Example of Frequency Planning An example network in a specific place, BTS are densely located. Thetopography is plain. The maximum BTS configuration is S3/3/2

Initial planning:


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Example of Frequency Planning Final frequency planning:


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Chapter 4 Neighbor cell planning


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WhyHandover is based on the neighbor relationship .

Existing problem of neighbor planning

No neighbor relationship, no handover

Co-BCCH and co-basic between adjacent cells lead to handover

failure.redundant neighbors

missing neighbor


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Neighbor Cell Description

There are table BA1 and table BA2.

Table BA1 describes BCCH frequencies of the adjacent cells tobe measured when the MS is in idle mode.

Table BA2 describes BCCH frequencies of the adjacent cells to

be measured when the MS is in dedicated mode.

There are two kinds of neighbors

bidirectional neighbors

unidirectional neighbors

Bidirectional neighbors are common, and unidirectionalneighbors are used in special condition, such as overshooting


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B

C

A

A

The signals of cell A covers some areas far away from thiscell. It is overshooting.

When MS moves from this area towards B and C

in dedicated mode, the signal is worse and worse.

since cell B and C is not the cell As neighbor,

call drop will occur finally.

There are three solution:

Adjust the downtilt of the antenna

Adjust the transmitting power of the BTS

Add B and C as the neighbor of cell A, no need to add

A to B and C, that is unidirectional neighbor.

(make sure that there are no co-BCCH and co-BSIC in neighbor list)

Overshooting and Unidirectional Neighbor


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The cells of co-site must be set as neighbor cells

The cells confronting directly must be added to neighbor list

The cells facing toward the same direction should be neighbors

The cells shooting by the original cellThe cells shooting at the original cell

The cells, one site apart, face to face should be neighbor cells.

Neighbor Planning Principle


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Demonstration (ideally)

co-site cellConfronting cell

same directional cell

one site apartface to face cell

Original cell


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