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Recherche & développement Etude des nouveaux formats de modulation pour la montée en débit dans le réseau d'accès optique 28/03/2008 – Journée de doctorant.

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Présentation au sujet: "Recherche & développement Etude des nouveaux formats de modulation pour la montée en débit dans le réseau d'accès optique 28/03/2008 – Journée de doctorant."— Transcription de la présentation:

1 recherche & développement Etude des nouveaux formats de modulation pour la montée en débit dans le réseau d'accès optique 28/03/2008 – Journée de doctorant ENSTB DUONG Thanh Nga Encardrant à FT: GENAY Naveena Directeur de thèse: SIMON Jean-Claude

2 recherche & développement Slide 2 Outline Introduction  Contexte Experimentation  Low-cost MB-OFDM for remote modulation of colorless ONU  Direct modulation of 2.5GHz DFB laser at a bit rate of 10Gbit/s Conclusion and perspective 1 2 3

3 recherche & développement Slide 3 Outline Introduction  Contexte Experimentation  Low-cost MB-OFDM for remote modulation of colorless ONU  Direct modulation of DFB laser at a bit rate of 10Gbit/s Conclusion and perspective 1 2 3

4 recherche & développement Slide 4 1. Introduction (1) Interest of OFDM for the optical access network ApplicationDébit requis Téléchargement des données2 Mb/s VoIP, Video-telephony, Videoconferencing1 Mb/s Musique à la demande (contenu multimédia) 2 Mb/s Jeux en ligne1 Mb/s TV numérique SD3 Mb/s TV numérique HD10 Mb/s TV numérique HD canaux additionnels (2 HD DTV) 20 Mb/s

5 recherche & développement Slide 5 Increase the capacity and decrease the cost of the system in optical access network  Increase the bit rate up to 10Gbit/s and more  Increase the transmission distance up to 100km without chromatic dispersion compensation 1.Fiber chromatic dispersion 2.Rayleigh Backscattering in architecture colorless ONU 3.Cost of system Solution Low-cost ONU module Direct modulation of laser To use advanced modulation format which is robust to fiber chromatic dispersion like DB, DPSK or OFDM modulation format 1. Introduction (2) Interest of OFDM for the optical access network

6 recherche & développement Slide 6 Interest of OFDM Duo-binary (DB) Un spectre est plus comprimé que celui du NRZ Plus tolérance à la dispersion chromatique Détection simple Complexité de l'émetteur DPSK/DQPSK Appliquer la technique remodulation La complexité du récepteur → coût élevé DPSK/DQPSK-ASK Forte tolérance à la DC La complexité de l'émetteur et du récepteur Faible sensibilité au récepteur OFDM Technique de transmission multi-porteuses Utiliser l'algorithme FFT/IFFT Chaque sous-porteuse est modulé par un format de modulation numérique différent Spectre de DB, NRZ, DPSK et RZ Le signal modulé DPSK

7 recherche & développement Slide 7 What is OFDM ? Widely use in the radio communication DAB (Digital Audio Broadcasting) DVB-T (Digital Video Broadcasting-Terrestrial) DRM (Digital Radio Mondiale) Wireless system Multi-carriers modulation format which uses a large number of closely-spaced orthogonal sub-carriers Use FFT/IFFT algorithm Each sub-carrier is modulated with a conventional modulation (QPSK, m-QAM, etc…) 1. Introduction (3) Interest of OFDM for the optical access network

8 recherche & développement Slide 8 1. Introduction (5) Interests of OFDM for optical access network Why we use OFDM for optical access network?  High density of information (Bit/s/Hz) → increase the bit rate without increasing RF cost (using low bandwidth component)  More tolerant to fiber chromatic dispersion (multi-path resilience) and we can optimize the transmission performance by adjusting the modulation format on each sub-carrier → 10G compatible  Could be implemented with DSP technique on fast and low cost devices  Reuse existing development in radio system (ISO/IEC DIS26908 UWB standard for MB-OFDM)  Improve the transmission performance with the help of FEC (BER = without FEC)

9 recherche & développement Slide 9 Outline Introduction  Contexte Experimentation  Low-cost MB-OFDM for remote modulation of colorless ONU  Direct modulation of DFB laser at a bit rate of 10Gbit/s Conclusion 1 2 3

10 recherche & développement Slide Experimentation (1) Low-cost MB-OFDM for remote modulation of colorless ONU Bidirectional transmission on 20km single-fiber hybrid WDM/TDM- PON architecture CW laser at 1550nm sent downstream Upstream data was generated by MB-OFDM at 1.92Gbit/s (3 OFDM bands at a bit rate of 640Mbit/s for each band) CW 1xN ONU Rx 20km OLT 1.92Gbit/s OFDM CW CW laser CWDM Splitter Remote modulation

11 recherche & développement Slide 11 Filter: CWDM having 0.6dB insertion losses and bandwidth of 20nm EAM: 14dB insertion losses, 10dB extinction ratio and bandwidth of 12GHz 2SOAs: 18dB optical gain 3 OFDM bands centred at 744MHz, 1272MHz and 1800MHz. 128 sub-carriers modulated by QPSK format each band SOA 1 CWDM EAM OFDM Signal SOA 2 CW signal 1 Modulated upstream signal 1 2. Experimentation (2) Low-cost MB-OFDM for remote modulation of colorless ONU, EAM solution

12 recherche & développement Slide 12 Received signal's constellation 2. Experimentation (3) Low-cost MB-OFDM for remote modulation of colorless ONU, EAM solution BTB transmission, upstream transmission for 1x16 splitting ratio

13 recherche & développement Slide 13 Remote modulation was possible on a single fiber hybrid architecture There are 2dB penalty for 1x8 splitting ratio and 6dB for 1x16 splitting ratio 2. Experimentation (4) Low-cost MB-OFDM for remote modulation of colorless ONU, EAM solution BTB 1x8 1x16 2dB 6dB

14 recherche & développement Slide Experimentation (7) Comparison with NRZ signal SOA 1 CWDM EAM NRZ SOA 2

15 recherche & développement Slide 15 Remote modulation was also possible on a single fiber hybrid architecture Only a splitting ratio of 1x8 was achieved for EAM solution and no splitter could be added for R-EAM solution (at 1.3Vp-p input at R-EAM)-error floor for 1x2 splitting ratio at 2Vp- p EAM solution R-EAM solution 1x8 1x16 No splitter 1x4 1x2 (pour 2Vp-p) 2. Experimentation (8) Comparison with NRZ signal

16 recherche & développement Slide 16 Measured factorOFDM remote modulation NRZ remote modulation ArchitectureWDM/TDM-PON Launched power laser 2dBm Bit rate1.92Gbit/s2Gbit/s SNR19dB (BER<10 -9 )19dB (BER>10 -6 ) Achieved splitting Ratio (BER<10 -9 ) 1x16 (SNR = 19dB)1x8 (SNR = 23dB) For EAM solution 2. Experimentation (9) Comparison with NRZ signal

17 recherche & développement Slide 17 Discussion OFDM modulation is a good candidate as a cost effective solution for colorless ONU OFDM format is more tolerant to Rayleigh backscattering than NRZ format in a bidirectional link Increase the bit rate in optical access network GPON → 10G in access 1. Fiber chromatic dispersion 2. Expensive component 3. Chirp of components Low cost infrastructure and low cost ONU module 1. Low cost components 2. Colorless ONU 3. RF cost vs optical cost 4. Fiber single architecture Colorless ONU 1. Rayleigh Backscattering

18 recherche & développement Slide 18 Outline Introduction  Interest of OFDM modulation for the optical access network Experimentation  Low-cost MB-OFDM for remote modulation of colorless ONU  Direct modulation of low-cost laser at a bit rate of 10Gbit/s Conclusion 1 2 3

19 recherche & développement Slide 19  Direct modulation of 2.5GHz DFB laser by 10Gbit/s AMOOFDM signal  64 sub-carriers  The m-QAM mapping varies from 4-QAM to 32-QAM  Transmission distance was taken to be 20km, 50km and 110km  No dispersion compensation Encoded data out Optical receiver A/D converter DSP demodulation Negotiation between Tx and Rx S/P M-QAM mapper IFFT P/S AWG DFB laser Encoded data in 20km, 50km, 110km SMF DSP modulation AOV 2. Experimentation (1) Direct modulation of DFB laser at a bit rate of 10Gbit/s

20 recherche & développement Slide Experimentation (2) Direct modulation of DFB laser at a bit rate of 10Gbit/s Sub No.1 Sub No.31 Sub No.23 Sub No.10

21 recherche & développement Slide Experimentation (3) Direct modulation of low-cost laser at a bit rate of 10Gbit/s – DFB laser  BER k is the bit error rate of k th sub-carrier  ND is the number of sub-carrier which contain the real data  The transmission is possible on 110km SMF  A BER of was obtained at a received optical power of -16dBm  The penalties for 20km and 50km optical links are negligible (the sensibility is considering at BER of )  The penalty on 110km optical link was approximately 2dB because of chromatic dispersion

22 recherche & développement Slide 22  Modulate directly with signal NRZ-OOK at a bit rate of 10Gb/s using the same DFB laser and receiver  There was an error-floor at a bit rate of 9x10 -4 for BTB curve and at a bit rate of 3x10 -2 for 20km transmission.  Transmission over 50km and 110km SMF were impossible due to the effect of chromatic dispersion AMOOFDM is more tolerant to fiber chromatic dispersion than NRZ-OOK signal 2. Experimentation (4) Comparison with NRS modulation – DFB laser

23 recherche & développement Slide 23 Considering factors Direct modulation with AMOOFDM signal Direct modulation with NRZ-OOK signal ArchitectureTDM-PON Launch power9.6dBm Bit rate10Gb/s Transmission distance possible 110 km0 2. Experimentation (5) Comparison with NRZ modulation – 2.5GHz DFB laser

24 recherche & développement Slide 24 Discussion  AMOOFDM modulation is a good candidate as a cost effective solution for optical access network in order to increase the capacity (bit rate and transmission distance)  AMOOFDM format is more tolerant to fiber dispersion chromatic than NRZ format Increase the capacity in optical access network GPON → 10G in access Transmission distance → 100km 1. Fiber chromatic dispersion 2. Expensive component 3. Chirp of components

25 recherche & développement Slide 25 Outline Introduction  Contexte Experimentation  Low-cost MB-OFDM for remote modulation of colorless ONU  Direct modulation of DFB laser at a bit rate of 10Gbit/s Conclusion and perspective 1 2 3

26 recherche & développement Slide Conclusion A remote modulation scheme was presented for upstream transmission in hybrid WDM/TDM-PON single fiber architecture A solutions are proposed for the colorless ONU: EAM solution. A bit rate of 1.92Gbit/s was archived for each wavelength Comparison between NRZ and OFDM remote modulation for both solutions was performed OFDM format is more robust to Rayleigh Backscattered light than NRZ-OOK modulation 10Gb/s transmission is experimentally demonstrated over 110km SMF by direct modulation of 2GHz bandwidth DFB laser without dispersion compensation A comparison between NRZ-OOK format and AMOOFDM format was performed at a bit rate of 10Gb/s AMOOFDM modulation format is more tolerant with fiber chromatic dispersion than NRZ-OOK format

27 recherche & développement Slide 27 Thank you for your attention Any question ? This work was performed in the framework of E-Photon One network of excellence and the French ANTARES project

28 recherche & développement Slide 28 Annexe (1) Definition of EVM

29 recherche & développement Slide Introduction (4) Interest of OFDM for the optical access network


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