1. B-VHF Final Project Results – Brussels – 19. September 2006 Page: 1 Air Ground Communication Focus Group Meeting Brussels, 19. September 2006 B-VHF – Final Results C. Rihacek (FRQ), M. Schnell (DLR) Christoph.Rihacek@frequentis.com, Michael.Schnell@dlr.de

2. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 2 Version: 1.0 Contents Main B-VHF Facts B-VHF Applicability Results of Physical Layer Simulations Sidelobe Suppression at the B-VHF Transmitter Simulation Scenarios for BER Evaluation BER Performance Without and With NBI Mitigation Validation of B-VHF Approach Laboratory measurements Measurement results Conclusions and Outlook

3. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 3 Version: 1.0 Main B-VHF Facts Broadband terrestrial cellular system based on multi- carrier technology MC-CDMA for forward link (G/A) OFDMA for reverse link (A/G) High capacity/high performance integrated voice and data link system tailored for specific aeronautical needs Supporting existing and emerging applications and services OFDM, OFDMA and MC-CDMA are mature technologies Proven by high-capacity bandwidth-efficient techniques, like DAB, DVB-T or W-LAN COTS products are already available (MC-CDMA adopted proposal for 4G) Most modern and spectrum efficient technology

4. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 4 Version: 1.0 Main B-VHF Facts B-VHF is primarily designed as overlay system Digital B-VHF Channel 8,33 kHz VHF AM-Channel 25 kHz VHF AM-Channel 25 kHz VHF VDL-Channel 25 kHz Frequency Analog Power Overlay concept enables in-band transition (e.g. VHF band)

5. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 5 Version: 1.0 Applicability of B-VHF B-VHF as overlay system (options) VHF band Extended VHF band (COM+NAV+MIL) DME band B-VHF without overlay (options) VHF (COM/NAV/MIL) band, free certain parts DME band, use respective parts MLS band for A-SMGCS applications

6. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 6 Version: 1.0 Sidelobe Suppression at Tx Objective: Minimization of interference towards legacy VHF systems Suppression to about -50 dB required Sidelobe suppression techniques: Deactivation of subcarriers (guard bands) Suppression not satisfactory Windowing Suppression good, but not satisfactory New approach: cancellation carriers f … … optimization range data carriers CCs data carriers CCs

7. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 7 Version: 1.0 Sidelobe Suppression at Tx w/o sidelobe suppression: -22.8 dB with 2 CCs: -38.3 dB with 2 CCs & windowing: -51.4 dB requirements fulfilled

8. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 8 Version: 1.0 Typical scenario Available channels from NAVSIM tool (worst case) Actual interferers from measurement campaign Worst case (WC) scenario 1 MHz with max. number of interferers from measurements Simulation Scenarios for FL Spectrum Allocation FL-ENR-WC ScenarioInterf. 6S/7W Strong Interferer Weak Interferer B-VHF Channel (+Weak Interferer) Skipped Channel 2S/2W Spectrum Allocation FL-ENR FL-TAKEOFF FL-PARK Scenario 1S/1W Interf. 1S/2W

9. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 9 Version: 1.0 BER Performance – ENR-WC Scenario 30 dB Synchronisation and channel estimation work properly Rx windowing not sufficient Additional NBI mitigation required required Rx power: -67 dBm ! worst case

10. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 10 Version: 1.0 NBI Mitigation Techniques Digital notch filtering Assumption: A/D converter with sufficient resolution Only for strong interferers Rx windowing in time domain Simple method Slight extension of time domain signal required Peak of interferer is not reduced Leakage compensation in frequency domain Leakage effect due to DFT operation Estimation and compensation of interference Requires few observation subcarriers (reduced number of data subcarriers only for weak interferers)

11. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 11 Version: 1.0 BER Performance – ENR-WC Scenario required Rx power: -88 dBm windowing only strong NBI compensated / notch filtered weak & strong NBI compensated combination with windowing worst case

12. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 12 Version: 1.0 Laboratory Measurements Measurements based on laboratory test-bed The B-VHF signal covers the maximum frequency range symmetrical to the desired centre frequency of the DSB-AM receiver System parameters N_FFT = 128 B = 266.66 kHz T_FRAME = 19.6 ms Tx windowing

13. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 13 Version: 1.0 Laboratory Measurements B-VHF interference on DSB-AM Eight measurement scenarios Three different airborne, one ground victim receiver Rockwell Collins VHF 920 Honeywell KY176 B Dittel FSG90 Rohde & Schwarz ground receiver type series 200 (EU230) Four different assessments Squelch break SINAD ratio degradation PESQ criteria Signal to pulse ratio level DSB-AM interference on B-VHF

14. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 14 Version: 1.0 Selected Measurement Results B-VHF interference on DSB-AM Squelch break and SINAD measurements determine maximum allowed B-VHF power @ DSB-AM victim receiver PESQ measurements lead to operational criteria for Frequency planning: Allow a B-VHF interference power value at the input of the DSB-AM airborne/ground receiver, which is 10 dB below the value which creates a 6 dB SINAD reduction at -85/-94 dBm. DSB-AM interference on B-VHF Without frequency gap (DSB-AM in B-VHF signal) S/I = 15 dB leads to BER of 10 -3 With two VHF channels gap (DSB-AM in frequency gap) S/I = 5 dB leads to BER of 10 -5 S/I < 3 dB forces synchronization failures

15. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 15 Version: 1.0 Selected Measurement Results Feasibility of overlay concept in VHF band Assessment based on laboratory test-bed Spectral mask assumptions (worst case) DSB-AM and B-VHF output power 41 dBm Most critical receiver considered 600 m spatial separation required Assessment results under given assumptions Additional attenuation of 47 dB required in frequency gaps for 8.33 kHz mode and four channels notched out Additional attenuation of 54 dB required in frequency gaps for 25 kHz mode and two channels notched out

16. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 16 Version: 1.0 Selected Measurement Results Potential improvements of laboratory test-bed Professional front-end design Considerable noise level reduction Higher dynamic range (high-resolution DAC) Additional interference suppression at Tx 25-30 dB Application of cancellation carrier technology Together with professional front-end design Increase bandwidth 6 dB From 266,67 kHz to 1066,67 kHz Respective power reduction in gap B-VHF output power reduction 10-20 dB Estimated power reduction Requires additional interference mitigation at B-VHF Rx > 55 dB

17. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 17 Version: 1.0 Conclusions Overlay concept and VHF in-band transition feasible Theoretical considerations and simulations Laboratory measurements Overlay concept requires additional efforts Implementation of overlay specific techniques Reduced capacity during deployment Applicability in non-VHF bands with or without overlay DME band for ground-based aeronautical communications MLS band for airport communications Scalability of B-VHF B-VHF easily scalable (data rate/capacity ~ bandwidth) Large bandwidth enables high rate/capacity aeronautical communications for additional/new applications

18. © B-VHF CONSORTIUM 2006 File: B-VHF_AGCFG_Meeting_3.ppt Author: FREQUENTIS Page: 18 Version: 1.0 Outlook Eurocontrol/FAA roadmap Voice communication in VHF band using DSB-AM Data link communications in DME band B-VHF technology is well suited for DME band Main characteristics remain High-capacity, high data-rate Flexibility and scalability Robustness against interference (DME, JTIDS) Possibility to apply overlay concept during deployment Proposal: Investigate B-VHF technology for DME band