GSM Frequency Planning 101564 563 565 572 571 578 570 568 564 567 566 580 580 579 569 576 588 564 585 584 582 Prepared by Tarik Ouazzani 1 Contents I) 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 2 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 B 0 1 S 1 T 1 T 2 T 2 T 2 T 3 T 3 T 3 T 4 T 4 T 4 T 5 T 5 T 5 T 6 T 6 T 6 T 7 T 7 T 7 T TCH2 Radio 3 BCCH Radio One Sector T 0 T TCH1 Radio Part I Frequency Planning 4 Why do we use frequency planning? • Efficient use of the frequency spectrum • Minimize interference • Improvement in voice quality 5 Uplink Vs Downlink UP LIN DO WN LI N K K Radio tower Cell phone 6 . 7 . 20 MHz Duplex spacing. 300 Carriers. PCS 1900 : 2*60 MHz Bands. GSM 900 : 2*25 MHz Bands. 125 Carriers. 80 MHz Duplex spacing. 95 MHz Duplex spacing.450 (Tetra): Being Introduced PCS GSM 850 : 2*25 MHz Bands. 45 MHz Duplex spacing. 375 Carriers. DCS 1800 : 2*75 MHz Bands. 125 Carriers. 8 . 710 MHz + (0.2 MHz) x (n-512) Fd (n) = Fu (n) + 80 MHz Fu = uplink frequency Fd = downlink frequency 1 n 124 512 n 885 512 n 810 9 .2 MHz) x (n-511) Fd (n) = Fu (n) + 95 MHz GSM 1900 Fu (n) = 1.Channel Numbering GSM 900 Fu (n) = 890 MHz + (0.2 MHz) x n Fd (n) = Fu (n) + 45 MHz GSM 1800 Fu (n) = 1.850.2 MHz + (0. 2)/0.2)/0.2+0.2]+512=711 10 .2]+512 N=[(1885-1850.Channel Numbering Block E: 1885-1890 and 1965-1970 The Channel Numbers : 586 to 611.2*(N-512) N=[(Fl(N)-1850. Fl(N)=1850.8-1850.2]+512=687 N=[(1889.2)/0. Carrier • Need to know which carriers are available in the project • Put the frequency range that the FCC allow Band A Channel Number 512-586 D B E F 587-611 612-686 687-711 712-736 G 737-811 11 . • Maximizing the number of times each channel may be reused in a given geographic area is the key to an efficient cellular system design.Reuse Factor • Low power transmitters to allow frequency reuse at much smaller distances. q= reuse factor R= center-to-vertex distance A D= Co-channel separation j=2 q= D/R R 2 2 D= i j ij i=3 A i= along any chain of hexagons o 60 j= counter clockwise turn 12 . Reuse Factor (cont’d ) • Frequency Reuse factor = 3x9 f2 f1 f2 f1 f3 f2 f3 f2 f1 f3 f2 f1 f3 f3 13 f2 f1 f2 f3 f1 f3 f1 f3 f2 f1 . Reuse Factor ( cont’d) • Frequency Reuse Factor = 4x12 f3 f1 f4 f1 f3 f1 f4 f2 f3 f1 f4 f4 f2 f3 f4 f2 f3 f1 f4 f2 f3 f1 f2 f2 14 . Reuse Factor( cont’d ) • Frequency Reuse Factor = 7x21 f2 f3 f4 f3 f5 f6 f4 f6 f7 f5 f7 f1 f6 f1 f2 f3 f1 f2 f4 f5 f7 f1 f3 f2 f6 f3 f2 f4 f5 f7 f1 f3 f4 f3 f5 f6 f1 f2 f4 f5 f4 f6 f7 f2 f3 f5 f6 f7 15 f4 f1 . C/I • Co-channel Interference Power(dBm) 9 dB Desired signal Interfering signal fo F (MHz) • Between the cells having the same BCCH • More than 9 dB difference doesn't effect 16 . C/I (cont’d) • Co-channel Interference example [-79. -80.……] -70 dBm 515 A2 515 C 9dB I CI 9 C= -70 dBm I 79 dBm A1 • Lower or equal than –79 dBm is acceptable 17 . 18 .C/I (cont’d) • Adjacent Interference Power( dBm) 9 dB fo Fo+200 KHz (for 1st Adjacent Interference) F ( MHz) • Between the adjacent cells • Interfering signal can have signal level difference up to 9 dB for the 1st Adjacent channel. C/I (cont’d) • 1st Adjacent Interference example [-61. -62.……] -70 dBm 516 515 C 9dB I C I 9 (for 1st Adjacent Interference) A2 C= -70 dBm I 61 dBm A1 • Lower or equal than –61 dBm is acceptable 19 . C/I (cont’d) Relation Co-channel 1 st adjacent channel 2 nd adjacent channel 3 rd adjacent channel Name C/I C/A1 C/A2 C/A3 Spacing ( kHz) 0 200 400 600 Protection (dB ) 9 -9 -41 -49 20 . 687 used as a Guard Band.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). 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 700 701 702 703 704 705 706 707 708 709 710 711 TCH 21 . C1 690 B1 f3 f1 f4 f2 A3 A1 C3 C2 B3 688 B2 696 698 694 697 689 A2 D3 D2 D1 692 699 694 691 693 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 700 701 702 703 704 705 706 707 708 709 710 711 TCH 22 .Pattern N=4 • BCCH planning first. Then we match it with the TCH Planning. • Several steps are required: Best Server C/I plots Drive test Data : RXQual (0 to 7) Need to be 0.Interference Table • List of all the Frequencies that can cause interferences for a cell. 23 . Possible Interferences 688 Adjacent Interference 690 Site A 692 698 Site C 696 694 691 689 Adjacent Interference Adjacent Interference Site D Site B 693 697 699 695 24 . Frequency Plan For 1 Pattern BSC: TBD National Color Code: 3 Site Id Site A Site B Site C Site D Orientation 0 120 240 0 120 240 0 120 240 0 120 240 BCCH 688 692 696 689 693 697 690 694 698 690 694 698 TCH 700 704 708 701 705 709 702 706 710 703 707 711 25 . Pattern N=4 f3 f1 f4 f1 f4 f2 f3 f1 f2 f4 f2 f1 f4 f3 f1 f4 f3 f1 f2 f3 f3 f4 f2 f2 26 . Part II BSIC Planning 27 . 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 color codes 28 . VT 4…) • BCC: (0 to 7 ) Planned by the RF Engineer.BSIC Allocation • BSIC=NCC+BCC • NCC : (0 to 7 ) predefined for a Carrier ( AWS can be 3 . • 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 29 . • 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. 30 .BSIC Allocation BCCH = A1 BSIC = 30 BCCH = A1 BSIC = 30 Same BSIC + Same BCCH = Drop Call Best Server BCCH = A1 BSIC = 31 BCCH = A1 BSIC = 30 Different BSIC + Same BCCH = Call on the best server (9 dB better) Radio tower Radio 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. BSIC Plan 32 30 30 32 32 31 31 30 33 33 33 31 31 . BSIC Plan f3 f3 F1 36 f3 f4 f2 f3 F1 30 f4 f2 f2 Reuse of BSIC 30 – Far Enough F1 37 f4 f3 F1 35 f2 f2 f3 f4 f2 F1 34 f4 F1 33 f4 f3 F1 30 f2 f3 f4 f3 F1 31 f4 f2 f4 f4 f2 F1 32 f3 32 . BSIC Plan BSC: TBD National Color Code: 3 Site Id Site A Orientation 0 120 240 0 120 240 0 120 240 0 120 240 BSIC 30 30 30 31 31 31 32 32 32 32 32 32 BCCH 688 692 696 689 693 697 690 694 698 690 694 698 TCH 700 704 708 701 705 709 702 706 710 703 707 711 Site B Site C Site D 33 . BSIC Plan For Every BSC BSIC PLAN FOR BSC XX 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 Site A2 Site A3 30 Site A1 Site B1 Site B2 Site B3 31 Site C1 Site C2 Site C3 32 Site D1 Site D2 Site D3 33 34 35 36 37 • Optimization Purposes: you can check with this table what is the Interferer • BSIC Planning : Help Choosing the BSIC Available. 34 . Part III Neighbors Planning 35 . Check Stats Monthly (BSC Dump). 36 . • When a HO occurs the mobile get a new NL from the New Sector.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). Possible HO Site A Site C Site D Site B 37 . Neighbor List StartUp Neighbors Cell Name CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site CELL Site Neighbors Site A2 Site A1 Site A2 Site B2 Site B1 Site B1 Site C2 Site C1 Site C1 Site D2 Site D1 Site D1 A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 Site A3 Site A3 Site A1 Site B3 Site B3 Site B2 Site C3 Site C3 Site C2 Site D3 Site D3 Site D2 Site B1 Site B1 Site B1 Site A2 Site A2 Site A2 Site B1 Site B1 Site B1 Site B1 Site B1 Site B1 Site B2 Site B2 Site B2 Site A2 Site A2 Site A2 Site B2 Site B2 Site B2 Site B2 Site B2 Site B2 Site B3 Site B3 Site B3 Site A3 Site A3 Site A3 Site B3 Site B3 Site B3 Site B3 Site B3 Site B3 Site C1 Site C1 Site C1 Site C1 Site C1 Site C1 Site A1 Site A1 Site A1 Site A1 Site A1 Site A1 Site C2 Site C2 Site C2 Site C2 Site C2 Site C2 Site A2 Site A2 Site A2 Site A2 Site A2 Site A2 Site C3 Site C3 Site C3 Site C3 Site C3 Site C3 Site A3 Site A3 Site A3 Site A3 Site A3 Site A3 Site D1 Site D1 Site D1 Site D1 Site D1 Site D1 Site D1 Site D1 Site D1 Site C1 Site C1 Site C1 Site D2 Site D2 Site D2 Site D2 Site D2 Site D2 Site D2 Site D2 Site D2 Site C2 Site C2 Site C2 Site D3 Site D3 Site D3 Site D3 Site D3 Site D3 Site D3 Site D3 Site D3 Site C3 Site C3 Site C3 38 . To reach the Mobile the Network need to know which LAC it is located. 39 .LAC • Location Area Code: LAC. • From time to time the Network page the Mobile to update the location of the Mobile. • 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. (208 for France. 40 .Final Frequency Plan BSC: TBD National Color Code: 3 Site Id Site A Orientation 0 120 240 0 120 240 0 120 240 0 120 240 BSIC 30 30 30 31 31 31 32 32 32 33 33 33 BCCH 688 692 696 689 693 697 690 694 698 691 695 699 TCH 700 704 708 701 705 709 702 706 710 703 707 711 MCC XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX MNC YY YY YY YY YY YY YY YY YY YY YY YY LAC 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 CELL ID 10000 10001 10002 10100 10101 10102 10200 10201 10202 10300 10301 10302 BSC TBD MSC TBD Site B TBD TBD Site C TBD TBD Site D TBD TBD MCC: Mobile Country Code: Unique for the Country. CELL ID: Each Cell ID has to be Unique In the Network. USA is ?? MNC: Mobile Network Code: Unique for the Carrier (AWS is ??). Part IV Frequency Hopping 41 . the Quality Indicators and Drive tests. the following conclusions can be derived.Advantages Based on the performance measurements. • Call Drop Rate (TCH) 9 % Improvement Much Easier Frequency Plan. More Tolerance for the RXQual. MaxRxQual=5 42 . 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). BCCH 688 689 690 691 692 693 694 695 696 697 698 699 Hop1 Hop2 Hop3 700 703 706 709 701 704 707 710 702 705 708 711 TCH 43 . No Hopping allowed in the BCCH channel. 687 used as a Guard Band. Hopping Planning BCCH. Hop3 698. Hop2 699. Hop1 689. Hop3 695. Hop2 696. Hop1 690. Hop3 694. Hop3 44 . Hop2 697. Hop2 691. Hop1 Site C 692. TCH 688. Hop1 Site D Site B 693. 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). 45 .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). 3.HSN and MAIO • Ensure that the HSN is unique for all cells that may cause interference to each other (random hopping). 2. per TRX and not per sector) • Hop1: 0. 2. • A good choice of MAIO is as follows:(Allocated per hopping group. 5 • Hop3: 0. 4 46 . 4 • Hop2: 1. Frequency Hopping Table BT S-N o Site _ID SiteA SiteA SiteA SiteB SiteB SiteB SiteC SiteC SiteC SiteD SiteD SiteD Se ctor 1 2 3 1 2 3 1 2 3 1 2 3 MAIO N umbe r H oppCa of T R X rr_1 1 0 1 2 1 4 1 0 1 2 1 4 1 0 1 2 1 4 1 0 1 2 1 4 H SN 1 1 1 2 2 2 3 3 3 4 4 4 Ma lloc_0 Ma lloc_1 Ma lloc_2 Ma lloc_3 Ma lloc_4 Ma lloc_5 Ma lloc_6 Ma lloc_7 Ma lloc_8 700 703 706 709 701 704 707 710 702 705 708 711 700 703 706 709 701 704 707 710 702 705 708 711 700 703 706 709 701 704 707 710 702 705 708 711 700 703 706 709 701 704 707 710 702 705 708 711 47 . Questions? 48 . Exercise 1 • Cellular Block A: Calculate the Channel Numbers 49 . * Frequency Plan Hopping * BSIC Plan * Neighbor List.(Ch512Ch586): * Frequency Plan No Hopping.Exercise 2 • PCS Block A (1930-1935 MHz) . 50 . Frequency Plan No Hopping BCCH TCH Frequency Plan With Hopping BCCH TCH 51 . BSIC Plan BSIC PLAN FOR BSC XX 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 52 . Neighbor List CELL CELL CELL CELL CELL CELL CELL CELL CELL CELL CELL CELL Site Site Site Site Site Site Site Site Site Site Site Site A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 53 . 54 .