Optical Code Design for Multi-Wavelength-OOC Optical CDMA system Claire GOURSAUD Mikaël MORELLE

Optical Code Design for Multi-Wavelength-OOC Optical CDMA system Claire GOURSAUD Mikaël MORELLE Anne JULIEN-VERGONJANNE Christelle AUPETIT-BERTHELEMOT Jean-Pierre CANCES Jean-Michel DUMAS Philippe GUIGNARD XLIM Dpt-C²S² UMR CNRS 6172 ENSIL - University of LIMOGES FRANCE goursaud@ensil.unilim.fr

Motivations Optical CDMA: Optical Code Division Multiple Access • Spread Spectrum technique • Inspired from radio communications (mobile phone …) • Allocation to each user a specific code • Multiple Access method: users  one common resource

Motivations • D=155Mbit/s up to 1 Gbit/s per user • Passive Optical Networks  30 users • BER (Bit Error Rate) < 10-9  Possible solution : O-CDMA Alternative to TDMA and WDMA techniques

Motivations O-CDMA Incoherent Coherent Unipolar codes (1D or 2D) All optical system Partially optical system

Electrical part – Emission Optical part CDMA coding Mux Data (laser) CDMA Decoding Demux Electrical part –Reception Motivations For low cost : electronic devices

Motivations • Performances degraded due to • MAI (Multiple Access Interference) • Beat noise • Thermal noise electronic devices: • Limited bandwidth B • Short code length F (for high data rate D)

Outline • 2D-OCDMA system • 2 Dimensional coding method • 2D DS-OCDMA • Conventional Correlation Receiver (CCR) • Structure • Performance analysis • Parallel Interference Cancellation receiver (PIC) • Structure • Performance analysis • Design of 2D codes

t  D  F (L,F) low Wavelength interference  L 2 Dimensional coding method • MWOOC : Multi-Wavelength Optical Orthogonal Codes • (L,F,W,λa,λc) • L : number of wavelengths • F : code length • W : code weight • λa : auto correlation value • λc : cross correlation value

10MWOOC (FxF,W,1,1) : impose L=F • 11MWOOC(LxF,W=λc+2,1, λc) : impose W=3 High flexibility 10G.C.Yang, W.C.Kwong, “Performance Comparison of Multiwavelength CDMA and WDMA + CDMA for Fiber-Optic Networks”, IEEE Trans. on comm., vol.45, n°11, pp. 1426-1434, nov. 1997. 11S-S.Lee and S-W.Seo, “New construction of Multiwavelength Optical Orthogonal Codes”, IEEE Trans. on comm., vol. 50, n°12, pp. 2003-2008, dec. 2002. 2 Dimensional coding method New Construction MWOOC (LxF,W,1,1) - Any value of L : W  L  F - Any value of W Lmin = W : MWOOC (LxF,W=L,1,1)

Fmin max( W(W-1)+1, 30 – L) 30 users  ê ú - F 1 £ Nooc ê ú - W ( W 1 ) ë û 2 Dimensional coding method 1D OOC code [a0, a1, …, aw-1] : an OOC(F, W=L, 1, 1) position vector F : Prime Number  FCode matrices { [ i, j*ai ] } { [ i, a0 ], [ i, a1 ], …, [ i, aw-1 ] } With i  [0, L-1], j  [0, F-1]  LCode matrices Cardinality : NMWOOC = F + L

2 Dimensional coding method  1 1 1 1 1 1  1 1 1 1 t t Example:MWOOC(5x23,5,1,1) OOC(23,5,1,1): (0, 1, 3, 8, 14) { [ 0, j*0 ] ; [ 1, j*1 ] ; [ 2, j*3 ] ;[ 3, j*8 ] ; [ 4, j*14 ] } j  [0, 22] { [ i, 0] ; [ i, 1] ; [ i, 3] ;[ i, 8] ; [i, 14] } i  [0, 4], NMWOOC(5x23,5,1,1) = 28 j=3 i=2

bi1(t){0,1} r1,F(t) MultiWavelength laser λ1 RL,F(t) Wavelength MUX  λL rL,F(t) biN(t) Electrical part Optical part 2 Dimensional Emission scheme DS-OCDMA : Direct Sequence OCDMA

CCR #1 Optical to Electrical Converter (OEC) r1,F(t) O / E  Wavelength DEMUX RL,F(t) S O / E rL,F(t) Errors occur only when = 0 Conventional Correlation Receiver (CCR)

Conventional Correlation Receiver (CCR)

CCR # 2 ˆ ( 2 ) b i - + ˆ ( k ) b RL,F(t) å CCR # i i CCR #1 ˆ ( 1 ) b i ˆ ( ) N b Errors occur only when = 1 i CCR # N Parallel Interference Cancellation (PIC) Receiver

Parallel Interference Cancellation (PIC) Receiver C.Goursaud, et al., “Improvement of Parallel Interference Cancellation technique with hard limiter for DS-CDMA systems”, IEEE GLOBECOM 2005, St-Louis, MO, USA, 28 Nov – 2 Dec, 2005. Session Photonic Technologies PT06.

2D code design D = 155 Mbit/s CCR: MWOOC(12x137,12,1,1) B = F.D = 21 GHz B = F.D = 6.5 GHz PIC: MWOOC(6x43,6,1,1)

MWOOC + PIC: F L = W SNR 2D code design AWGN noise perturbation • SNR  [15, 25] dB:Noise dominates CCR(12x137,12) has better performance due to the high weight • SNR  [25, 30] dB:MAI dominates PIC(6x43,6) has better performance due to the PIC efficiency to remove MAI • SNR  [30, 40] dB : Performance in the noiseless case • CCR  SNRmin=30 dB BER = 10-9: • PIC  SNRmin=28 dB

Conclusion New construction of Multi-Wavelength Optical Orthogonal Code High flexibility Short temporal code length Minimal number of wavelength equal to the weight BER  10-9 D  155 Mbit/s N = 30

Thank you for your attention

Optical Code Design for Multi-Wavelength-OOC Optical CDMA system Claire GOURSAUD Mikaël MORELLE

Optical Code Design for Multi-Wavelength-OOC Optical CDMA system Claire GOURSAUD Mikaël MORELLE

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