IMPLEMENTATION OF ADAPTIVE MODULATION FOR A/G ...

IMPLEMENTATION OF ADAPTIVE MODULATION FOR A/G

COMMUNICATION SYSTEM USING ZEPTOSDR

34th Digital Avionics System Conference-2015

Zakaria El Alaoui Ismaili, Wessam Ajib, Omar A. Yeste-Ojeda and René Landry Jr.,

12015-09-07

AGENDA

1. Introduction

2. Air-to-Ground Links Problematic

3. Adaptive modulation implementation

4. Test and performance

5. Conclusion

22015-09-07 Agenda

Benefits of soft defined radio (SDR) for aviation applications

Decreases size, weight, cost and power consumption

Reconfigurability

Robustness

Flexibility

High data rate

Multiple channels versatility

Interoperability

Scalability

2015-09-07 3Introduction (1/3)

2015-09-07 4

Context of the work

AVIO-505 project: “Software defined radios for highly

integrated system architecture”

• Objectives:

– Integration of navigation, communication and surveillance

systems under a single universal reconfigurable platform

• Partners:

– Academic: ETS Montreal, Ecole Polytechnique Montreal, UQAM

– Industrial: Bombardier, MDA, Marinvent Corporation, Nutaq

Introduction (2/3)

Objective of the work

To design a SDR system equipped by an adaptive

modulation technique able to autonomously choose

the most suitable modulation among BPSK, QPSK,

8PSK, 16QAM and 64QAM based on the estimation of

link quality measured by the signal to noise ratio (SNR)

in real time.

2015-09-07 5Introduction (3/3)

Air-to-Ground Links Problematic

Safety related services represented by Air Traffic Services Control (ATSC) for pilots and controllers, and Air Operation Control (AOC).

Non safety-related services which can be also provided in cabin for airline administrative Communications (AAC) or for passengers (APC) [1].

62015-09-07 Air-to-Ground Links Problematic (1/3)

Air to ground link overview


The (A/G) communication systems use the line-of-sight (LOS) in veryhigh frequency (VHF) aeronautical narrowband (from 118 to 137 MHzwith 25 kHz or 8.33 kHz per channel) whereas satellite communication(SATCOM) is solicited to ensure the links in oceanic areas [1].

L-band (between 960 ̶ 1164 MHz) termed L-band digital aeronauticalcommunication system (LDACS) is recommended to decrease thespectrum saturation [2].

Cognitive radio was also proposed to be adopted in aeronautical A/Gcommunications to provide broadband services for AOC and APC.Nevertheless, the VHF, L-band, low Earth orbit (LEO) SATCOM still themost promising candidates for A/G communication systems thanks totheir high technical performance, low cost, and low risk [3].

Why adaptive modulation?


– Maximize the data rate to ensuremore services– Minimize transmission errors

Maximize Information Transfer requires high efficiency modulation but susceptible to higher error rate

Minimize Transmission Errors requires low efficiency modulation

Robust and secure communication

What we need?

Solution Modulation agility

Adaptive modulation implementation

92015-09-07 AM implementation (1/4)

• Analytical Principle



• Switching SNR values for Adaptive Modulation

For SNR ˂ 12.6dB we need to add coding for gain benefit

Switching strategy can be improved

o 12.6dB ˂ SNR ≤ 17.5dB

o 17.5dB ˂ SNR ≤ 19.4dB

o 19.4dB ˂ SNR ≤ 25.5dB

o SNR > 25.5dB

QPSK

8PSK

16QAM

64QAM



Hardware Tool: ZeptoSDR platform (Nutaq) [4]

Software Tool: GNURadio [5]

• Main components:– Radio420X: High quality radio module

– Xilinx Zynq FPGA (pass-through mode)

– Dual ARM Cortex-A9

• Features– Remote and embedded operation

– GNU Radio support

Block diagram of data transmission with adaptive modulation


Test and performance : set-up

AVIO-505 : DME/DME system (7/8) 132015-09-07 Tests and performance (1/5)

• Transmitter Tx: It consists of a ZeptoSDR platform connected to alaptop with Ethernet gigabit cable. Fitted with GNU radio software,the laptop is able to control transmission power, to display boththe transmitted signals constellation and to feed-back themodulation control message.

• Receiver Rx: It consists of a ZeptoSDR platform connected to asecond laptop. However, this part is responsible for SNR estimationand receiving data.

Adaptive modulation constellation diagrams for QPSK, 8PSK, 16QAM and 64QAM

142015-09-07 Tests and performance (2/5)

Instantaneous QPSK to 8PSK switching at the receiver


Switching delay


Solution: implementing a modulation time offset estimated at the receiver

Solution: increasing the SNR thresholds for all modulations

Comparison of theoretical and experimental BER performance


Conclusion and future works

An experimental implementation of adaptive modulationtechnique for air-to-ground (A/G) communication systemsusing a software defined radio approach was presented.

The system implementation provides a transmission, of a realtime captured video, equipped by an adaptive modulationtechnique. The system autonomously chooses the mostsuitable modulation among BPSK, QPSK, 8PSK, 16QAM basedon the estimation of link quality measured by the signal tonoise ratio (SNR) in real time.

More investigations are currently done to improve 64QAMtransmission quality in order to offer more bits per symbol.

Adaptive coding is currently being implemented to haveadaptive modulation and coding (AMC) for (A/G)communication systems.

182015-09-07 Conclusion

2015-09-07 19

[1] M. S. Ben Mahmoud, C. Guerber, N. Larrieu, A. Pirovano and J. Radzik,"Aeronautical Air−Ground Data Link Communications", John Wiley & Sons 2014.

[2] M. Raja, A.P. Vinod and A.S. Madhukumar, April 2015, "DME interferencemitigation for LDACS1 based on decision-directed noise estimation," in 2015Integrated Communication, Navigation, and Surveillance Conference (ICNS),pp.21-23.

[3] D. S. Ponchak, R. D. Apaza, B. Haynes, J. M. Wichgers and A. Roy, March 2015,"A study of future communications concepts and technologies for the NationalAirspace System part IV", in 2015 IEEE Aerospace Conference, pp.7-14.

[4] Nutaq, “ZeptoSDR,”. Available: http://nutaq.com/en/products/zeptosdr.

[5] GNU Radio – Wiki Start [Online]. Available: http://www.gnuradio.org

References

Thank you

For more information about LASSENA or AVIO-505 project: [email protected]

Questions?

202015-09-07

IMPLEMENTATION OF ADAPTIVE MODULATION FOR A/G ...

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