ppt planning

7/27/2019 ppt planning

1/38

1

GSM Frequency Planning 101

563

564

580565

564

566567

568

569

570

571572 580

576

579578

564

582

584

585

588

Prepared by Tarik Ouazzani


2/38

2

Contents

I) Introduction : BCCH vs. TCH

II) Frequency Planning

Why do we use frequency planning?

Channel Numbering

Reuse Factor

C/III) BSIC Planning

Why do we use frequency planning?

BSIC Numbering

III) Neighbors List

IV) Frequency Hopping


3/38


4/38

4

Frequency Planning

Part I


5/38

5

Why d

owe use frequency planning?

Efficient use of the frequency spectrum

Minimize interference

Improvement in voice quality


6/38

6

Uplink Vs D

ownlink

Radio tower Cell phone

DOWNLINK

UPLINK


7/38

7

450 (Tetra): Being Introduced

GSM 850 : 2*25 MHz Bands, 20 MHz Duplex spacing, 125Carriers.

GSM 900 : 2*25 MHz Bands, 45 MHz Duplex spacing, 125Carriers.

DCS 1800 : 2*75 MHz Bands, 95 MHz Duplex spacing, 375Carriers.

PCS 1900 : 2*60 MHz Bands, 80 MHz Duplex spacing, 300 Carriers.

PCS


8/38

8


9/38

9

Channel Numbering

GSM 900(n) = 890 MHz + (0.2 MHz) x n

(n) = (n) + 45 MHz

GSM 1800

(n) = 1,710 MHz + (0.2 MHz) x (n-511)

(n) = (n) + 95 MHz

GSM 1900

(n) = 1,850.2 MHz + (0.2 MHz) x (n-512)(n) = (n) + 80 MHz

1241 ee n

810512 ee n

885512 ee n

dF

dF

uF

uF

uF

dF

uF

uF

uF

uF

dF

= uplink frequency

= downlink frequency


10/38

10

Channel Numbering

Block E: 1885-1890 and 1965-1970

The Channel Numbers : 586 to 611.

Fl(N)=1850.2+0.2*(N-512)

N=[(Fl(N)-1850.2)/0.2]+512

N=[(1885-1850.2)/0.2]+512=687

N=[(1889.8-1850.2)/0.2]+512=711


11/38

11

Carrier Need to know which carriers are available in the project

Put the frequency range that the FCC allow

Band Channel Number

A 512-586

D 587-611

B 612-686

E 687-711

F 712-736

G 737-811


12/38

12

Reuse Factor Low power transmitters to allow frequency reuse at much smaller

distances. Maximizing the number of times each channel may be reused in a

given geographic area is the key to an efficient cellular system design.

q= reuse factor

R= center-to-vertex distanceD= Co-channel separation

q= D/R

D=

i= along any chain of hexagons

j= counter clockwise turn

ijji 22

R

A

A

o60

i=3

j=2


13/38

13

Reuse Factor (contd )

f2

f2

f3

f1

f1f3

f2

f3

f1

Frequency Reuse factor =

f2

f3

f1

3x9

f1

f3

f1

f2

f2f1

f3

f1

f3

f2

f2

f3


14/38

14

Reuse Factor ( contd)

f1

f2

f3

f4

f1

f3

f4f2

4x12

f1

f2

f3

f4

f1

f3

f2f4

f2

f1

f3

f4

f1

f2

Frequency Reuse Factor =

f3

f4


15/38


16/38

16

C/I Co-channel Interference

fo

Desired signal

Interfering signal

9 dB

F (MHz)

Power(dBm)

Between the cells having the same BCCH

More than 9 dB difference doesn't effect


17/38

17

C/I (contd) Co-channel Interference example

515

515-70 dBm

A1

A2

dBI

C9u

9u

C= -70 dBm

79eI dBm

Lower or equal than 79 dBm is acceptable

[-79, -80,]

I


18/38

18

C/I (contd) Adjacent Interference

fo Fo+200 KHz F ( MHz)

9 dB

Power( dBm)

Between the adjacent cells

Interfering signal can have signal level difference up to 9 dB

for the 1st Adjacent channel.

(for 1st Adjacent Interference)


19/38

19

C/I (contd) 1st Adjacent Interference example

515

516

-70 dBm

A1

A2

dBI

C9u

9u

C= -70 dBm

61eI dBm

Lower or equal than 61 dBm is acceptable

[-61, -62,]

I

(for 1st Adjacent Interference)


20/38

20

C/I (contd)

Relation Name Spacing ( kHz) Protection (dB )

Co-channel C/I 0 9

1 st adjacent channel C/A1 200 -9

2 nd adjacent channel C/A2 400 -41

3 rd adjacent channel C/A3 600 -49


21/38

21

Block E Channels

Calculation for a BTS Configuration Of 2/2/2:

Reuse Factor N=4

Block E has 5 MHz = 25 Channels. (Channel 687 to 711).

687 used as a Guard Band.

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

BCCH 688 689 690 691 692 693 694 695 696 697 698 699

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

TCH 700 701 702 703 704 705 706 707 708 709 710 711


22/38

22

Pattern N=4

f1

f4

f3

f2A1

C1

A2A3

D1

D2

D3

C2C3 B1

B2B3

688

690

692696

691

694

699

694698 689

693697

BCCH planning first, Then we match it with the TCH

Planning.

A B A B A B

B

A B A B A B

T


23/38

23

Interference Table

List of all the Frequencies that can cause interferences for a cell.

Several steps are required:

Best Server

C/I plots

Drive test Data : RXQual (0 to 7) Need to be 0.


24/38

24

Possible Interferences

690

694

698

689

693

697

691

695699

688

692

696

Adjacent

Interference

Adjacent

Interference

Adjacent

Interference

Site A Site C

Site BSite D


25/38

25

Frequency Plan For 1 PatternBSC: TBD

National Color Code: 3

Site Id Orientation BCCH TCHSite A 0 688 700

120 692 704

240 696 708

Site B 0 689 701

120 693 705

240 697 709

Site C 0 690 702

120 694 706

240 698 710

Site D 0 690 703120 694 707

240 698 711


26/38

26

Pattern N=4

f1

f2

f3

f4

f1

f3

f4f2

f1

f2

f3

f4

f1

f3

f2f4

f2

f1

f3

f4

f1

f2

f3

f4


27/38

27

BSIC Planning

Part II


28/38

28

BSIC BSIC: Base Transceiver Station Identity Code

used to distinguish neighboring base

stations two components: Network Color Code (NCC) Base Station Color Code (BCC) directly adjacent PLMN and BS must have

different colorcodes


29/38

29

BSIC Allocation

BSIC=NCC+BCC

NCC : (0 to 7 ) predefined for a Carrier ( AWS can be 3 , VT 4)

BCC: (0 to 7 ) Planned by the RF Engineer.

Helps the mobile stations to distinguish between two neighboring

cells sharing the same BCCH

BSIC combination has to be unique for all cells that are defined in

the neighbor list.

The Mobile Recognize the BTS as it Neighbors or as the one it is

connecting to by the Combination BSIC+BCCH

BSIC=Base Station Identity Code

NCC= Network Color Code

BCC= Base Station Color Code


30/38

30

BSIC Allocation

Rad i

t

rRad i

t

r

If a Mobile receives 2 same BCCH with the Same BSIC. It will be impossible for him

to make the difference between the 2 BTSs. ----> Drop Call

BSIC is the way the mobile make the difference between the 2 BTSs.

BCCH = A1

BSIC = 30

BCCH = A1

BSIC = 30

Radi

t

rRadi

t

r

BCCH = A1

BSIC = 30

BCCH = A1

BSIC = 31

Best Server

Same BSIC + Same BCCH = Drop Call

Different BSIC + Same BCCH = Call onthe best server (9 dB better)


31/38


32/38

32

BSIC Plan

F1 30

f2

f3

f4

F1 31

f3

f4

f2

F1 34

f2

f3

f4

F1 35

f3

f2

f4

f2

F1 33

f3

f4

F1 32

f2

f3

f4

F1 36f2

f3

f4

F1 37

f3

f4

f2

f3

f4

F1 30

f2

f3

f4

Reuse of BSIC 30 Far Enough


33/38

33

BSIC PlanBSC: TBD

National Color Code: 3

Site Id Orientation BSIC BCCH TCH

Site A 0 30 688 700

120 30 692 704240 30 696 708

Site B 0 31 689 701

120 31 693 705

240 31 697 709

Site C 0 32 690 702

120 32 694 706

240 32 698 710

Site D 0 32 690 703

120 32 694 707

240 32 698 711


34/38

34

BSIC Plan For Every BSC

Optimization Purposes: you can check with this table what is the Interferer

BSIC Planning : Help Choosing the BSIC Available.

BCCH 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711

BSIC

30 Sit

1 Sit

2 Sit

3

31 Sit

1 Sit

2 Sit

3

32 Sit

1 Sit

2 Sit

3

33S

it

1 Sit

2 Sit

3

34

35

36

37

BSIC PLA FOR BSC XX


35/38

35

Neighbors Planning

Part III


36/38

36

Neighbors Planning Find ALL the possible HO

If one Neighbor is Missing ---> Possible Drop

Call

Put in the List the Maximum numbers of

Neighbors (most vendors have 20 neighbors in the

NL). Check Stats Monthly (BSC Dump).

When a HO occurs the mobile get a new NL from

the New Sector.


37/38

37

Possible HO

Site A Site C

Site BSite D


38/38

Documents

ppt planning