58606407 GSM Frequency Planning Training 101

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GSM Frequency Planning 101

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Prepared by Tarik Ouazzani

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ContentsI) Introduction : BCCH vs. TCH

II) Frequency Planning

• Why do we use frequency planning?

• Channel Numbering

• Reuse Factor

• C/I

II) BSIC Planning

• Why do we use frequency planning?

•      BSIC Numbering

III) Neighbors List

IV) Frequency Hopping

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BCCH vs. TCH

• Each BTS Sector Need one BCCH• The first Radio is the BCCH radio even if only

one Time Slot is the BCCH• The Second, Third…Radio are the TCH radios

0 1 2 3 4 5 6 7

T T T T T TTT

0 1 2 3 4 5 6 7

T T T T T TTT

0 1 2 3 4 5 6 7

T T T T T TSB BCCH Radio

TCH1 Radio

TCH2 Radio

One Sector

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Frequency Planning

Part I

5

Why do we use frequency planning?• Efficient use of the frequency spectrum

• Minimize interference

• Improvement in voice quality

6

Uplink Vs Downlink

Radio tower Cell phone

7

450 (Tetra): Being Introduced

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

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

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

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

PCS

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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 n

810512 n

885512 n

dF

dF

uF

uF

uF

dF

uF

uF

uF

uF

dF

= uplink frequency

= downlink frequency

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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

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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

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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 distance

D= 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

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Reuse Factor (cont’d )

f2

f2

f3

f1

f1f3

f2

f3

f1

• Frequency Reuse factor =

f2

f3

f1

3x9

f1

f3

f1

f2

f2

f1

f3

f1

f3

f2

f2

f3

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Reuse Factor ( cont’d)

f1

f2

f3

f4

f1

f3

f4

f2

4x12

f1

f2

f3

f4

f1

f3

f2

f4

f2

f1

f3

f4

f1

f2

• Frequency Reuse Factor =

f3

f4

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Reuse Factor( cont’d )• Frequency Reuse Factor = 7x21

f3

f6

f7

f5

f2

f1

f5

f3

f5

f4

f3

f7

f2

f4

f4

f5

f6

f7

f1

f1

f4

f2

f6

f1

f3

f7

f5

f1

f4

f7

f2

f4

f6

f2

f5

f3

f1

f3

f2

f6

f4

f3

f3

f6

f2

f5

f4

f1

f7f6

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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

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C/I (cont’d)• Co-channel Interference example

515

515-70 dBm

A1

A2

dBI

C9

9

C= -70 dBm

79I dBm

• Lower or equal than –79 dBm is acceptable

[-79, -80,……]

IC

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C/I (cont’d)• 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)

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C/I (cont’d)• 1st Adjacent Interference example

515

516

-70 dBm

A1

A2

dBI

C9

9

C= -70 dBm

61I dBm

• Lower or equal than –61 dBm is acceptable

[-61, -62,……]

IC

(for 1st Adjacent Interference)

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C/I (cont’d)

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

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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 D3BCCH 688 689 690 691 692 693 694 695 696 697 698 699

A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3TCH 700 701 702 703 704 705 706 707 708 709 710 711

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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.

A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3BCCH 688 689 690 691 692 693 694 695 696 697 698 699

A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3TCH 700 701 702 703 704 705 706 707 708 709 710 711

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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.

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Possible Interferences

690

694698

689

693697

691

695699

688

692696

Adjacent Interference

Adjacent Interference

Adjacent Interference

Site A Site C

Site BSite D

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Frequency Plan For 1 Pattern

BSC: TBD

National Color Code: 3

Site Id Orientation BCCH TCHSite A 0 688 700

120 692 704240 696 708

Site B 0 689 701120 693 705240 697 709

Site C 0 690 702120 694 706240 698 710

Site D 0 690 703120 694 707240 698 711

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Pattern N=4

f1

f2

f3

f4

f1

f3

f4

f2

f1

f2

f3

f4

f1

f3

f2

f4

f2

f1

f3

f4

f1

f2

f3

f4

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BSIC Planning

Part II

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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

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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 CodeNCC= Network Color CodeBCC= Base Station Color Code

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BSIC Allocation

Radio towerRadio tower

• 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 = 30BCCH = A1

BSIC = 30

Radio towerRadio tower

BCCH = A1

BSIC = 30

BCCH = A1

BSIC = 31

Best Server

Same BSIC + Same BCCH = Drop Call

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

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BSIC Plan

30

32

3030

33

33

33

3232 31

3131

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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 36

f2

f3

f4

F1 37

f3

f4

f2

f3

f4

F1 30

f2

f3

f4

Reuse of BSIC 30 – Far Enough

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BSIC PlanBSC: TBD

National Color Code: 3

Site Id Orientation BSIC BCCH TCHSite A 0 30 688 700

120 30 692 704240 30 696 708

Site B 0 31 689 701120 31 693 705240 31 697 709

Site C 0 32 690 702120 32 694 706240 32 698 710

Site D 0 32 690 703120 32 694 707240 32 698 711

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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 711BSIC

30 Site A1 Site A2 Site A3

31 Site B1 Site B2 Site B3

32 Site C1 Site C2 Site C3

33 Site D1 Site D2 Site D3

34353637

BSIC PLAN FOR BSC XX

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Neighbors Planning

Part III

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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.

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Possible HO

Site A Site C

Site BSite D

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Neighbor List

StartUp Neighbors

Cell Name NeighborsCELL Site A1 Site A2 Site A3 Site B1 Site B2 Site B3 Site C1 Site C2 Site C3 Site D1 Site D2 Site D3CELL Site A2 Site A1 Site A3 Site B1 Site B2 Site B3 Site C1 Site C2 Site C3 Site D1 Site D2 Site D3CELL Site A3 Site A2 Site A1 Site B1 Site B2 Site B3 Site C1 Site C2 Site C3 Site D1 Site D2 Site D3CELL Site B1 Site B2 Site B3 Site A2 Site A2 Site A3 Site C1 Site C2 Site C3 Site D1 Site D2 Site D3CELL Site B2 Site B1 Site B3 Site A2 Site A2 Site A3 Site C1 Site C2 Site C3 Site D1 Site D2 Site D3CELL Site B3 Site B1 Site B2 Site A2 Site A2 Site A3 Site C1 Site C2 Site C3 Site D1 Site D2 Site D3CELL Site C1 Site C2 Site C3 Site B1 Site B2 Site B3 Site A1 Site A2 Site A3 Site D1 Site D2 Site D3CELL Site C2 Site C1 Site C3 Site B1 Site B2 Site B3 Site A1 Site A2 Site A3 Site D1 Site D2 Site D3CELL Site C3 Site C1 Site C2 Site B1 Site B2 Site B3 Site A1 Site A2 Site A3 Site D1 Site D2 Site D3CELL Site D1 Site D2 Site D3 Site B1 Site B2 Site B3 Site A1 Site A2 Site A3 Site C1 Site C2 Site C3CELL Site D2 Site D1 Site D3 Site B1 Site B2 Site B3 Site A1 Site A2 Site A3 Site C1 Site C2 Site C3CELL Site D3 Site D1 Site D2 Site B1 Site B2 Site B3 Site A1 Site A2 Site A3 Site C1 Site C2 Site C3

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LAC

• Location Area Code: LAC.

• Planning the LAC can help Decrease the Signalization by decreasing the number of Authentications. When ever a subscriber enter a new LAC the network is informed of the

New LAC. • From time to time the Network page the Mobile to update

the location of the Mobile. To reach the Mobile the Network need to know which LAC it is located.

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Final Frequency PlanBSC: TBD

National Color Code: 3

Site Id Orientation BSIC BCCH TCH MCC MNC LAC CELL ID BSC MSCSite A 0 30 688 700 XXX YY 10000 10000 TBD TBD

120 30 692 704 XXX YY 10000 10001240 30 696 708 XXX YY 10000 10002

Site B 0 31 689 701 XXX YY 10000 10100 TBD TBD120 31 693 705 XXX YY 10000 10101240 31 697 709 XXX YY 10000 10102

Site C 0 32 690 702 XXX YY 10000 10200 TBD TBD120 32 694 706 XXX YY 10000 10201240 32 698 710 XXX YY 10000 10202

Site D 0 33 691 703 XXX YY 10000 10300 TBD TBD120 33 695 707 XXX YY 10000 10301240 33 699 711 XXX YY 10000 10302

MCC: Mobile Country Code: Unique for the Country. (208 for France, USA is ??

MNC: Mobile Network Code: Unique for the Carrier (AWS is ??).

CELL ID: Each Cell ID has to be Unique In the Network.

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Part IV

Frequency Hopping

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Advantages

Based on the performance measurements, the Quality Indicators and Drive tests, the following conclusions can be derived.

• Call Drop Rate (TCH)9 % Improvement

Much Easier Frequency Plan.

More Tolerance for the RXQual. MaxRxQual=5

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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.

• No Hopping allowed in the BCCH channel.

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

TCH 700 703 706 709 701 704 707 710 702 705 708 711Hop1 Hop3Hop2

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Hopping Planning

690, Hop1

694, Hop2698, Hop3

689, Hop1

693, Hop2

697, Hop3

691, Hop1

695, Hop2699, Hop3

688, Hop1

692, Hop2696, Hop3

Site C

Site BSite D

BCCH, TCH

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HSN and MAIO

• When a GSM phone is served by a cell that is hopping over a set of frequencies, the separate traffic channels hop over the allocated frequencies according to a hopping sequence number (HSN). The traffic channels with the same HSN hop over the same frequencies in the same order but are separated in time by a mobile allocation index offset (MAIO).

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HSN and MAIO

• Ensure that the HSN is unique for all cells that may cause interference to each other (random hopping).

• A good choice of MAIO is as follows:(Allocated per hopping group, per TRX and not per sector)

• Hop1:0, 2, 4• Hop2:1, 3, 5• Hop3:0, 2, 4

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Frequency Hopping Table

BTS-No Site_ID SectorNumber of TRX

MAIOHoppCa

rr_1 HSN Malloc_0Malloc_1Malloc_2Malloc_3Malloc_4Malloc_5Malloc_6Malloc_7Malloc_8SiteA 1 1 0 1 700 703 706 709SiteA 2 1 2 1 701 704 707 710SiteA 3 1 4 1 702 705 708 711SiteB 1 1 0 2 700 703 706 709SiteB 2 1 2 2 701 704 707 710SiteB 3 1 4 2 702 705 708 711SiteC 1 1 0 3 700 703 706 709SiteC 2 1 2 3 701 704 707 710SiteC 3 1 4 3 702 705 708 711SiteD 1 1 0 4 700 703 706 709SiteD 2 1 2 4 701 704 707 710SiteD 3 1 4 4 702 705 708 711

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Questions?

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Exercise 1

• Cellular Block A:

Calculate the Channel Numbers

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Exercise 2

• PCS Block A (1930-1935 MHz) - (Ch512- Ch586):

* Frequency Plan No Hopping.

* Frequency Plan Hopping

* BSIC Plan

* Neighbor List.

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Frequency Plan No Hopping

BCCH

TCH

Frequency Plan With Hopping

BCCH

TCH

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BSIC Plan

514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535

BSIC PLAN FOR BSC XX

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Neighbor List

CELL Site A1CELL Site A2CELL Site A3CELL Site B1CELL Site B2CELL Site B3CELL Site C1CELL Site C2CELL Site C3CELL Site D1CELL Site D2CELL Site D3

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