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  • First of all, I want to introduce my research area.
    Then, we will study the dispersive phenomenon in the fiber and go to the motivation for our research.
    In The main content part: I will describe both theoretical and simulation models of the system in detail, as well as visibly showing numerical result of our research.
  • Let me give you some overview information
  • For the optical network, we are using OOK.

    Time domain has disadvantage of high pulse rate, the SAE has disadvantage of dispersion.
  • _ Short guy goes slower

    _ Go ahead or behind the referent wavelength
  • Thank to the popular commercial simulation software suite called OptiSystem, we have built a simulation system, taking advantages of: bla bla…

  • _ Beta 2 is GVD parameter (as you see it determine how much the optical pulse would broaden on propagation)

    _ The signal is detected by the balanced detection so I just divide to two here and free-minded use this PcL for further calculation.
  • From the formula of received power of chip pulse, we will calculate the receive power of both signal and MAI at the receiver and then receiver noise from those power values, and ultimately we get BER.
  • _ The encoder composed by a sequence of Uniform Fiber Bragg Grating.

    _ We divide the whole spectrum to wavelength components equivalent to chips. Each chip’s power will be Pc.
  • We can see the signal spectrum in this image, it’s quite easy too compare the too signal spectrum. That two are equal in case of bit 0 received and in case of it 1, power on additive branch has more power.

    _ Common balanced detection structure
  • At the end, we have built the computer simulation model for … 3 users.
  • We can see the bound of signal after multiplexing.

    _ can be remove..
  • The experiment use m-sequence code and PIN receiver
    Thank to the popular commercial simulation software suite called OptiSystem, we have built a simulation system, taking advantages of: bla bla…

  • Can mention about the multiplexing technique
    _ time slot
    _ private wavelength
    _ is assigned code to encode end decode signal
  • The balance detection, theoretically it completely cancel the Multiple Access interference.
  • SAE/OCDM System

    1. 1. ICEIC Indonesia 2013 SAE/OCDM SYSTEMS USING APD RECEIVER OVER LINEAR DISPERSIVE CHANNEL Nguyen Tat Thang & Anh T. Pham The University of Aizu Computer Communications Lab Saturday, June 21, 2014 SAE/OCDM Systems
    2. 2. ICEIC Indonesia 2013 Contents • Introduction • Optical code-division multiplexing (OCDM) techniques • Dispersion in optical fiber • Motivation • Theoretical Model and Analysis • Spectral amplitude encoding (SAE) OCDM System • Linear Dispersive Channel • Theoretical BER over Linear Dispersive Channel • Simulation Model • Results & Discussions • Conclusions Saturday, June 21, 2014 SAE/OCDM Systems
    3. 3. ICEIC Indonesia 2013 Overview • SAE/OCDM has been considered as a promising technique for the next-generation optical access and local networks • Impact of dispersion is one of critical factors to performance of SAE/OCDM system • This has been analyzed theoretically and experimentally [3][5] • In this work, we implement a simulation model using OptiSystem® software suite for analyzing the performance of SAE/OCDM systems • We especially focus on modeling and analyzing the impact of dispersion Saturday, June 21, 2014 SAE/OCDM Systems
    4. 4. ICEIC Indonesia 2013 • Time Domain Encoding: • Spectral Amplitude Encoding (Freq. domain): Saturday, June 21, 2014 SAE/OCDM Systems OCDM (Optical Code Division Multiplexing) 1 0 t t Tb Tc = Tb / NTc 01010101 t f 01010101 0 1 0 1 0 1 0 1 Broadband source t f Tc=Tb Dispersion phenomena 1 2 3 4
    5. 5. ICEIC Indonesia 2013 Impact of Dispersion Saturday, June 21, 2014 SAE/OCDM Systems 1 0 1 0 0 0 1 • Chromatic dispersion (group velocity dispersion, aka. GVD) • Peak reduction • Pulse Broadening • Time Skewing
    6. 6. ICEIC Indonesia 2013 Motivation (1) • Experimental study on the impact of dispersion has been reported • H. Tamai et al., “Experimental study on time-spread/wavelength-hop optical code division multiplexing with group delay compensating en/decoder,” IEEE Photon. Technol. Lett., 2004. • It is the experimental study with real implementation • Limitation: expensive, not flexible, delayed, difficult to analyze when scalability is required • Theoretical study using the Linear dispersive channel model for analyzing the performance of SAE/OCDM systems • Ngoc T. Dang et al., “Performance Analysis of Spectral Amplitude Encoding OCDM Systems over a Linear Dispersive Optical Channel”, IEEE/OSA J. Optical Comm. & Netw., 2009. • Could easily analyze with different configuration, settings • Validation required, some assumption is still far from practical conditions SAE/OCDM SystemsSaturday, June 21, 2014
    7. 7. ICEIC Indonesia 2013 Motivation (2) • Understanding the impact of dispersion is critical and needed to be carefully considered in the system design • Our proposal • A trade-off solution • Analyze the performance of SAE/OCDM system over dispersive channel using optical simulation system • Advantages • Closer to the real implementation • However, it is • Cheaper • Flexible: Easy to modify system’s parameters, • More quickly  faster R&D process • Scalable: easily analyze with a large number of users Saturday, June 21, 2014 SAE/OCDM Systems
    8. 8. ICEIC Indonesia 2013 THEORETICAL ANALYSIS Saturday, June 21, 2014
    9. 9. ICEIC Indonesia 2013 SAE/OCDM System: Principle Transmitter - User #1 Code C1 Transmitter - User #2 Code C2 … Transmitter - User #K Code CK Receiver - User #1 Code C1 Receiver - User #2 Code C2 Receiver - User #K Code CK … Combiner K • 1 Splitter 1 • K Dispersive optical channel SAE/OCDM SystemsSaturday, June 21, 2014 APD2 C1 C1 APD1
    10. 10. ICEIC Indonesia 2013 Saturday, June 21, 2014 SAE/OCDM Systems Linear Dispersive Channel Model • The optical pulse propagation model with modified factors was used for analytical modeling: *Average received power of chip number i transmitting over L km of fiber Gaussian pulse peak power attenuation *Ps: Transmitted power per bit K: Number of users N: Code length T0: half width of Gaussian Pulse
    11. 11. ICEIC Indonesia 2013 System’s BER over Linear Dispersive Channels (APD Receiver) • Received desired signal power (after decoding): • Received MAI signal power (after decoding): • BER: SAE/OCDM Systems *Additive branch *Subtractive branch *Additive branch Saturday, June 21, 2014
    12. 12. ICEIC Indonesia 2013 CONSTRUCTION OF SIMULATION MODEL AND ANALYSIS Saturday, June 21, 2014
    13. 13. ICEIC Indonesia 2013 Simulation Model for Transmitter Saturday, June 21, 2014 SAE/OCDM Systems Hadamard code – N=12 ω=6 λ=3 Optical Power Combiner Ps Other Users PE = Pc (N -w)+ Pcw gw N -g0 æ è ç ö ø ÷ γw γ0 Ps Pc = Ps N 101010101010 Fiber Bragg Gratings
    14. 14. ICEIC Indonesia 2013 Simulation Model with APD Receiver Saturday, June 21, 2014 SAE/OCDM Systems Cm Cm Optical Splitter Optical Power Splitter Other User: 10101010 10100101 bit 1 bit 1 bit 0 bit 0
    15. 15. ICEIC Indonesia 2013 Results (Theoretical vs. Simulation) • The performances of system with two cases: considering dispersive channel and non-dispersive (only attenuation) channel. SAE/OCDM Systems * 3 x 500 Mb/s active users in total 8 users, 10 km optical fiber with attenuation 0.2dB/km, D = 16.75 ps/nm/km BER vs. APD gain, Ps=-17dBm BER vs. Ps, APD gain = 7 Saturday, June 21, 2014 0.5 dB
    16. 16. ICEIC Indonesia 2013 Conclusions & Summary • We have built the computer simulation model for SAE/OCDM system using APD receiver with 3 activating users in 8 users total • The well-matched simulation and theoretical results has validated the simulation model. The simulation model therefore could be used for OCDM system R&D • Next step: we will build the simulations for more complete models, with more practical parameters and more practical devices such as EDFA, dispersion shifted fiber. SAE/OCDM SystemsSaturday, June 21, 2014
    17. 17. ICEIC Indonesia 2013 Question time Thank you! SAE/OCDM SystemsSaturday, June 21, 2014
    18. 18. ICEIC Indonesia 2013 Some of recent experimental model for SAE/OCDM systems • Julien Penon et al., “Spectral-Amplitude-Coded OCDMA Optimized for a Realistic FBG Frequency Response”, Journal of Lightwave Technology, 2007. • Mohammad Reza Salehi et al., “Code Performance Comparison in SAC-OCDMA Systems under the Impact of Group Velocity Dispersion”, J. Opt. Commun., 2012 Saturday, June 21, 2014
    19. 19. ICEIC Indonesia 2013 Simulation of Linear Dispersive Channel SAE/OCDM Systems Without GVD With GVD 1549 nm 1554 nm Saturday, June 21, 2014
    20. 20. ICEIC Indonesia 2013 Transmitter: Principle Saturday, June 21, 2014 Laser Source Spectral Encoder Data (0,1) Cm channel (OF) Transmitter λ1 … λ5 … λ8 λ2 λ4 λ6 λ8 Ps P = Ps N ´w = Pcw Ps Cm: 0 1 0 0 1 1 1 0 λ1λ2λ3λ4λ5λ6λ7λ8 Hadamard code – N=8 ω=4 λ=2 Hadamard code: • Code length: N – number of chips • Code weight: ω – number of chip 1s • In-phase cross correlation: λ – number of similar chip 1s of two codes. • • RCm,Cn = cm,icn,i = w if m = n l if m ¹ n ì í ï îïi=1 N å w = N / 2,l = N / 4,RCm,Cn =w - RCm,Cn = N / 4 SAE/OCDM Systems
    21. 21. ICEIC Indonesia 2013 Motivation (2) (Obsoleted) • Problem • Theoretical model required to be validated • The practical experiments: expensive, not scalable, not flexible and delayed • Some proposed models have assumption is far from practical implementation. The dispersive characteristic of OF has not been consider in experiment. • Advantages • Scalable: large and flexible number of users • Easy to modify system’s parameters • Get the result quickly  faster R&D process • Cheaper than the real implementation Saturday, June 21, 2014 SAE/OCDM Systems
    22. 22. ICEIC Indonesia 2013 Multiplexing Techniques Saturday, June 21, 2014 SAE/OCDM Systems Time t λ Wavelength Time t Wavelength λ t λ Code • Codes used for multiplexing • Asynchronous access ability • Flexible number of users • Possibly cheaper Time division multiplexing(TDM) Wavelength division multiplexing(WDM) Code division multiplexing (CDM) • Time synchronization required • Limited speed by electronic processing • Wavelength management required • Expensive
    23. 23. ICEIC Indonesia 2013 Simulation Systems Saturday, June 21, 2014 SAE/OCDM Systems Other Users λ1=1549 λ2=1549.5 λ3=1550 λ4=1550.5 User 1 code: 11110000 λ5, λ6, λ7, λ8, Cm Cm Hadamard code – N=8 ω=4 λ=2 Optical Splitter Optical Power Splitter Optical Power Combiner Gratings Ps
    24. 24. ICEIC Indonesia 2013 SAE/OCDM Receiver Saturday, June 21, 2014 SAE/OCDM Systems Coupler (3dB) Decoder 1 Decoder 2 Threshold Detection Data (0,1) PD1 PD2 Cm Cm I2 I = I2-I1 I1 channel (OF) Pin1 = Ps N RC1,C1 Pin2 = Ps N RC1,C1 Receiver delay APD1 APD2 Balanced detection λ2 λ7 λ5 λ6 λ2 λ7 λ6 λ5
    25. 25. ICEIC Indonesia 2013 • Received power at receiver #1 (designate for user #1): • Complement code branch - data: • Direct code branch-data : • Multiple Access Interfering: • Balanced Detection: Saturday, June 21, 2014 SAE/OCDM Systems PD1 = Ps (gw - Ng0 ) 2gwK Theoretical Calculation PD2 = Ps (gw -wg0 ) 2gwK PI = 1 4K 1 K-1 å Ps - Ps (w + l)g0 gw æ è ç ö ø ÷ I1 = MÂ[(PD1 +PI )-(PD2 +PI )]
    26. 26. ICEIC Indonesia 2013 Spreading Sequence (Code) • m-sequence (N, (N+1)/2, (N+1)/4), Hadamard (N, N/2, N/4), MQC (N=p2+p, ω=p+1, λ=1) (p is odd prime number). • There are several construction of these code sets. Saturday, June 21, 2014 SAE/OCDM Systems