58606407 GSM Frequency Planning Training 101
Post on 13-Aug-2015
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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
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Why do we use frequency planning?• Efficient use of the frequency spectrum
• Minimize interference
• Improvement in voice quality
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Uplink Vs Downlink
Radio tower Cell phone
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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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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
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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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