Channel Occupancy and Capacity Analysis Snjezana Gligorevic and

Channel Occupancy and Capacity Analysis Snjezana Gligorevic and Michael Schnell German Aerospace Center - DLR

Overview Ø B-VHF in Current VHF Band Situation Ø Nav. Simulations Ø Channel Occupancy Measurements Ø B-VHF System Design Ø Conclusion Authors: Gligorevic and Schnell – DLR 2

Current VHF Band Situation – Theoretical 25 / 8. 33 k. Hz channel spacing All channels continuously allocated & used Power Analog Digital Authors: Gligorevic and Schnell – DLR 25 k. Hz VHF AM-Channel 25 k. Hz Frequency 8. 33 k. Hz VHF AM-Channel 25 k. Hz VHF VDL-Channel 3

Current VHF Band Situation – Practical 25 / 8. 33 k. Hz channel spacing Only a part of the allocated channels are used Not all channels are ‘seen’ with full power all the time Power Analog Digital Authors: Gligorevic and Schnell – DLR 25 k. Hz VHF AM-Channel 25 k. Hz Frequency 8. 33 k. Hz VHF AM-Channel 25 k. Hz VHF VDL-Channel 4

B-VHF Overlay System 25 / 8. 33 k. Hz channel spacing Only a part of the allocated channels are used Not all channels are ‘seen’ with full power all the time Power Analog Digital Authors: Gligorevic and Schnell – DLR 25 k. Hz VHF AM-Channel 25 k. Hz Frequency 8. 33 k. Hz VHF AM-Channel 25 k. Hz VHF VDL-Channel B-VHF Channel 5

Nav. Simulations Ø Worst Case Simulation 4 Considerable more occupied VHF channels expected than in measurement flights! 4 All ground stations (100% duty cycle) and ATC sectors within radio horizon considered. 4 Each ATC sector is represented by a worst-case interfering A/C, i. e. interfering A/C (100% duty cycle) is located at the border of ATC sector next to victim receiver (observation point). Authors: Gligorevic and Schnell – DLR 6

Nav. Simulations – Worst Case Interfering A/C B-VHF Cell ATC Sector Cell Radius Cell Center Authors: Gligorevic and Schnell – DLR B-VHF A/C DSB-AM A/C 7

Nav. Simulations Ø Worst Case Simulation 4 Considerable more occupied VHF channels expected than in measurement flights! 4 All ground stations (100% duty cycle) and ATC sectors within radio horizon considered. 4 Each ATC sector is represented by a worst-case interfering A/C, i. e. interfering A/C (100% duty cycle) is located at the border of ATC sector next to victim receiver (observation point). 4 Multiple observation points; 12 points on a circle representing a fictitious BVHF boundary Authors: Gligorevic and Schnell – DLR 8

Nav. Simulations – Multiple Observation Points ATC Sector B-VHF Cell Radius Cell Center Authors: Gligorevic and Schnell – DLR B-VHF A/C DSB-AM A/C 9

Nav. Simulations – Results Authors: Gligorevic and Schnell – DLR 10

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Nav. Simulations – Results Munich Airport (EDDM) Cell Size Flight Level Interference Power Threshold Available VHF Band 20 nm FL 50 -85 d. Bm 35. 7% 20 nm FL 250 -85 d. Bm 17. 6% 20 nm FL 50 -80 d. Bm 50. 0% 20 nm FL 250 -80 d. Bm 38. 8% 20 nm FL 50 -75 d. Bm 65. 5% 20 nm FL 250 -75 d. Bm 65. 7% 20 nm FL 50 -70 d. Bm 80. 8% 20 nm FL 250 -70 d. Bm 79. 1% 60 nm FL 50 -85 d. Bm 19. 7% 60 nm FL 250 -85 d. Bm 8. 4% 60 nm FL 50 -80 d. Bm 33. 0% 60 nm FL 250 -80 d. Bm 23. 6% 60 nm FL 50 -75 d. Bm 47. 0% 60 nm FL 250 -75 d. Bm 47. 1% 60 nm FL 50 -70 d. Bm 55. 4% 60 nm FL 250 -70 d. Bm 55. 0% Authors: Gligorevic and Schnell – DLR 13

Nav. Simulations – Results Brussels Airport (EBBR) Cell Size Flight Level Interference Power Threshold Available VHF Band 20 nm FL 50 -85 d. Bm 24. 7% 20 nm FL 250 -85 d. Bm 6. 4% 20 nm FL 50 -80 d. Bm 39. 6% 20 nm FL 250 -80 d. Bm 24. 7% 20 nm FL 50 -75 d. Bm 50. 3% 20 nm FL 250 -75 d. Bm 50. 4% 20 nm FL 50 -70 d. Bm 67. 2% 20 nm FL 250 -70 d. Bm 67. 2% 60 nm FL 50 -85 d. Bm 12. 2% 60 nm FL 250 -85 d. Bm 3. 8% 60 nm FL 50 -80 d. Bm 19. 3% 60 nm FL 250 -80 d. Bm 9. 1% 60 nm FL 50 -75 d. Bm 34. 9% 60 nm FL 250 -75 d. Bm 34. 9% 60 nm FL 50 -70 d. Bm 46. 3% 60 nm FL 250 -70 d. Bm 46. 1% Authors: Gligorevic and Schnell – DLR 14

Results of Measurements Bovingdon VOR Available VHF Band Radius of Orbit Flight Level Interferen ce Power Threshold Segment Half Orbit Whole Orbit 10 nm FL 340 -86 d. Bm 60. 58% 48. 30% 10 nm FL 340 -82 d. Bm 69. 78% 59. 33% 10 nm FL 340 -78 d. Bm 78. 84% 69. 45% 10 nm FL 340 -74 d. Bm 84. 10% 79. 50% 10 nm FL 340 -70 d. Bm 89. 36% 85. 61% 20 nm FL 260 -86 d. Bm 66. 80% 55. 52% 44. 24% 20 nm FL 260 -82 d. Bm 74. 87% 65. 70% 56. 53% 20 nm FL 260 -78 d. Bm 80. 82% 74. 16% 67. 50% 20 nm FL 260 -74 d. Bm 85. 68% 80. 93% 76. 18% 20 nm FL 260 -70 d. Bm 89. 71% 86. 32% 82. 93% 30 nm FL 160 -86 d. Bm 72. 68% 58. 54% 44. 40% 30 nm FL 160 -82 d. Bm 78. 55% 68. 26% 57. 97% 30 nm FL 160 -78 d. Bm 82. 98% 75. 09% 67. 20% 30 nm FL 160 -74 d. Bm 87. 16% 81. 35% 75. 54% 30 nm FL 160 -70 d. Bm 90. 39% 86. 41% 82. 43% Authors: Gligorevic and Schnell – DLR Worst case Simulations EBBR / EDDM 6. 4% / 17. 6% 67. 2% / 79. 1% 15

B-VHF System Design – Link Budget Analysis B-VHF Cell ATC Sector Max. Interference -95. 0 d. Bm Cell Radius Cell Center Distance? B-VHF A/C Power? DSB-AM A/C 41. 0 d. Bm Authors: Gligorevic and Schnell – DLR 16

Example – Link Budget Analysis Threshold: -75 d. Bm (65% VHF band available @ EDDM) B-VHF Cell Interference Power 10. 2 d. B above Signal Level Cell Radius 20 nm Interference Power 10. 2 d. B above Signal Level 42 nm Cell Center B-VHF A/C DSB-AM A/C -78. 4 d. Bm -75. 0 d. Bm 41. 0 d. Bm -88. 6 d. Bm 21. 0 d. Bm -85. 2 d. Bm -95. 0 d. Bm 24. 4 d. Bm Authors: Gligorevic and Schnell – DLR -95. 0 d. Bm 17

Conclusions Ø Interference towards DSB-AM can be avoided! h B-VHF Tx power < 21 d. Bm (A/C) and < 24. 4 d. Bm (GS) h With respect to SNR, small B-VHF Tx power no problem (SNR > 64 d. B for 25 kbit/s transmission per 25 k. Hz) h This holds even for the “-75 d. Bm” threshold (worst case) Ø Large interference from DSB-AM towards B-VHF h Worst case interference on used subcarriers within B-VHF system is 10. 2 d. B above B-VHF signal level h Actual interference is much lower then the simulated worst case h Actual interference is not present all the time (duty cycle!) h B-VHF overlay system able to cope with large interference power levels – Spread-spectrum system – Interference reduction by spreading (diversity) and coding Ø Final verification of B-VHF system concept with simulations Authors: Gligorevic and Schnell – DLR 18