Transcript Document
Simulation of High Speed Photonic Networks Professor Z. Ghassemlooy Optical Communications Research Group http://soe.unn.ac.uk/ocr/ School of Computing, Engineering and Information Sciences University of Northumbria at Newcastle, UK 1 Presentation Outline 1. Photonic Networks 2. Photonic Packet Switching 3. Photonic Router Modelling 4. OFDM 5. Results 3. Conclusions Eng. of S/W Pro., India 2009 2 Optical Communications 1st generation optical networks: packet routing and switching are mainly carried out using high-speed electronic devices. However, as the transmission rate continues to increase, electronically processing data potentially becomes a bottleneck at an intermediate node along the network. [bit/s] 1P 100T Traffic demand forecast (NEC–2001) 10T Total 1T Capacity increase : 2~4 times a year Data 100G 10G Bit cost decrease : 1/2 time a year Voice 1G 100M 1995 2000 2005 2010 Solution: All-optical processing & switching 3 Network Topology – An Overview Ref: Prof. Leonid G. Kazovsky, et al. “Broadband Fiber Access”, available online from http://www.comsoc.org/freetutorials/ Eng. of S/W Pro., India 2009 All-Optical Packet Switching Client Network 0111 Objectives • High Bit Rate • High Throughput Low-speed packet High-speed packet Low-speed packet 1011 Core Network Client Network 1001 1010 Header Processing! 0110 Edge Router (Ingress/Egress) with 4-bit address XXXX Core Router XXXX Eng. of S/W Pro., India 2009 5 Photonic Network - Packet Routing Optical vs. Electrical in High-speed Routing PL H O/E Client Network 0111 Ck Low-speed packet E/O Processing High-speed packet H 0100 Matching! Routing table Patterns Outputs 0000B (0D) OP1 0001B (1D) OP2 0010B (2D) OP1 0011B (3D) OP1 0100B (4D) OP2 0101B (5D) OP1 … … 1110B (14D) OP2 1111B (15D) OP1 Low-speed packet 1011 Core Network Client Network 1001 1010 0110 Edge Router (Ingress/Egress) with 4-bit address XXXX Core Router XXXX Optical domain Electrical domain High Speed >> 40 Gbit/s IC: Large scale, cheap, memory Speed limitation < 40 Gbit/s Complexity, costly, no memory Integration Light “Frozen”? “Opt. Capacitors”? All-Optical Processing Eng. of S/W Pro., India 2009 6 Photonic Network – All-optical Routing Optical Switching Unit Packet Output Signal Processing (2R, 3R, equalization) Input Controlling Header Extraction Contention Header Recognition Buffer Look-up Routing Table Clock Extraction Reconfiguration Main modules Optional modules Delay unit Splitter Aim: 1.To optimise the SMZ performance for all-optical functions. 2.To design a bi-directional SMZ and implement it in the router to reduce components, time and cost. Eng. of S/W Pro., India 2009 7 Photonic Network - Packet Routing Exhaustive Correlation Packet header is compared with all entries of a routing table for checking the matching Client Network 0111 Low-speed packet High-speed packet Low-speed packet 1011 Core Network Client Network N2N 1001 1010 0110 bit-wise AND operations Edge Router (Ingress/Egress) with 4-bit address XXXX Robust All-Optical Processing Core Router XXXX Our solution: Reduce routing table entries Minimise number of AND operations Pulse-Position-Modulation based Header Processing (PPM-HP) Eng. of S/W Pro., India 2009 8 Photonic Network - Packet Address Optical Packet Clock Payload Address a3 a2 a1 Tb LSB 1 Add. in Binary a0 0 0 1 Decimal value = 9 One Frame of 4-bit RZ OOK Ts PPM 0 1 Eng. of S/W Pro., India 2009 2 3 4 5 6 7 8 Bit duration: Tb 9 10 11 12 13 14 15 No. of slot L = 24 Slot duration: Ts = Tb /4 9 Photonic Network - Routing Table Port 1 1M Port 2 Conventional routing table (M = 3 ports) 2N entries Address patterns Decimal metric Output ports 00…000 0 Port 2 00…001 1 Port 1 00…010 2 Port 3 00…011 3 Port 1 00…100 4 Port 3 00…101 5 Port 2 00…110 6 Port 2 00…111 7 Port 1 … … … 11…10 2N-2 Port 2 11…11 2N-1 Port 1 Eng. of S/W Pro., India 2009 Port 3 Entry Positions (Decimal) 1 1,3,7,…,2N-1 Actual PPM frame (length 2N slots) … 0 1 2 3 PPM 2 … 0,5,6,…,2N-2 0 1 2 3 3 2 N-1 4 5 6 7 2 N-1 4 5 6 7 … 2,4,… 0 1 2 3 4 5 6 7 2 N-1 Pulse-position routing table 10 All-optical Packet-switched Router – PPM Touting Table A Clk A Clk Clock Extraction PPMA PPM Add. Conversion CP 1 PL Header Extraction … A PPRT Entry 1 Clk OSWM PL OSW2 A Clk … Entry 2 Matched pulse Entry M Port 2 Port M … OSWC &2 Synchronisation … OSWC &1 … CP M PL A Clk Port 1 CP 2 PL OSW1 All-optical Switch … … &M OSWC PPM-HP Eng. of S/W Pro., India 2009 11 Simulation Software to Model Routers OptiWave (systems, devices, components) http://www.optiwave.com/ R-Soft (systems & devices) http://www.rsoftdesign.com/ Photoss (WDM systems & devices) http://www.lenge.de/english/index.php Virtual Photonic Inc. (VPI) (systems & devices) http://www.vpiphotonics.com/ 12 Simulation Software - Matlab No optical communications tool box Complex to model optical networks – Need strong theory Can be used with other software packages such as VPI to save modelling and debugging time Ideal for the end users with a strong mathematical and programming background 13 Simulation Software - VPI Very powerful for optical networks and optical devices modelling Support C and Matlab Has visual interface (drag and drop) – e.g. oscilloscopes etc Provide extensive simulation examples and manuals Online discussion forum http://forums.vpisystems.com/ 14 VPI Simulation Software Optical Scope Laser Source A typical optical switch BER Tester SMZ Eng. of S/W Pro., India 2009 15 Simulation of Devices - SOA Semiconductor Optical Amplifier Best to use Matlab: Segmentisation of SOA improves accuracy Not possible with the current VPI Output signals Injection current (I) Output facet 1 Input signal w H Input signals t=0 t=l/vg Ni segment segment L 2 ………… .. ………… …. t=L/vg segment 5 output signal N(1) N(5) Input facet of active region Eng. of S/W Pro., India 2009 16 Simulation of Devices – SOA Results 1 120 0.8 100 Output gain Normalised gain 140 0.6 80 0.4 60 0.2 40 0 0 1 2 3 Time (s) 4 Total gain with no input 5 6 -9 x 10 =1530nm =1540nm =1550nm =1560nm =1565nm 20 1 2 3 4 5 6 Input power (mW) 7 8 9 10 Signal output gain corresponding to the input power at different wavelengths 17 Optical Switches Cat.1 Large scale (> 1616) Slow response (s-ms) Non-optically controlled MEMS* (Lucent Tech.) Bubbles* (Agilent) Cat.2 Small scale (22) Fast response (fs-ps) SMZ* (Japan) Full-optically controlled TOAD* (Princeton) • Crosstalk • Contrast 18 VPI – SMZ Switch OFDL-1 CP1 E2UA ,in (0) Input signal SOA1 UA LA Eout,1 = Eout (p ) + Eout (p ) UA Eout (p ) UA E1 (0) C2 Port 1 Tdelay Tdelay C1 E2 (p/2) LA CP2 C3 Port 2 C4 LA Eout (p / 2) UA LA Eout,2 = Eout (3p / 2) + Eout (p / 2) p SOA2 E1LA ,in( / 2) OFDL-2 PBS – Polarization beam splitter OFDL– Optical fibre delay line SMZ switching window 25 20 SMZ gain 15 10 5 0 40 Eng. of S/W Pro., India 2009 CP1=CP2 45 50 55 60 Time (ps) 65 70 75 19 VPI – SMZ Switch Data pulse train Optical receiver Eng. of S/W Pro., India 2009 20 VPI Simulation Software – Inverter Gate A A bar 1 0 0 1 CP 1 (CLK) Input packets SOA Output (A bar) Input (CLK) SOA Control pulse CP 2 (A) 50 Output1 45 40 CR (dB) 35 30 CR of CP CP 25 CR at output1 20 CR at output2 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Input packet pow er (dBm) 10 11 12 13 Output2 Packet Address Correlator To carry packet routing decision one needs to check (correlated) packet address with entries of routing table Matched A PP packet address One PPRT entry AND A*B B gate … … A AB SOA1 B in SOA2 Eng. of S/W Pro., India 2009 SW PPM-HP Router - Clock Extraction Optical packet Payload Clk Header Clk Clock Extraction 1 1 0 1 1 0 1 0 1 1 1 1 01 1 1 Clock, header and payload: same intensity, polarization and wavelength Clock extraction requirements: • Asynchronous and ultrafast response • High on/off contrast ratio of extracted clock Eng. of S/W Pro., India 2009 4 PPM-HP Router - Clock Extraction Clk GCP 12 12 SOA1 SOA1 22 12 in SMZ-1 22 22 SW Optical fiber span 22 Amplifier 22 in 12 SW SOA2 Polarization Controller (PC) Polarization Beam Splitter (PBS) SMZ-2 22 22 22 Attenuator SOA2 Optical delay • Self-extraction: packet as the control signal • High on/off contrast ratio: two switching-stage Eng. of S/W Pro., India 2009 5 Simulation – Clock Extraction 1st stage Crosstalk Extracted clock 2nd stage Packet in 13 VPI – Packet Address Conversion 1-N SP Converter a0 a1 a 2 a3 (a) SMZ3 SMZ2 SMZ1 SMZ0 a3 ))a2 a1 a0 (b) cSP 2 TS 0 x(t) Switch (0) s 1 2 TS 2 2 TS 1 Switch (1) 1 Switch (2) 1 2 TS 3 xPPM(t) Switch (3) PPM-ACM Eng. of S/W Pro., India 2009 26 12 SMZ Switch with a High Contrast Ratio low inter-output CR (< 10 dB) Output1 SMZ1 Input packets SMZ1_op2 CP SMZ2 CP (SMZ1_op1) Output2 (SMZ2_op1) inverter CEM CLK CP Improved CR (> 32 dB) CEM: clock extraction module Fibre Delay Line – Passive using Matlab Fibre loop B In A Out Switch C Eye diagram after 200 iterations without regeneration Eng. of S/W Pro., India 2009 Fibre Delay Line - Active with Regeneration Optical amplifier DSF fibre loop B In A Switch Out C Clock Optical regenerator Eye diagram after 200 iterations with regeneration Eng. of S/W Pro., India 2009 SMZ - Simulation Parameters Eng. of S/W Pro., India 2009 VPI – PPM Routing Table … Pe-i 1×2N-2 eB(t) … 0×Ts … … (2N-2-1)×Ts … -1)×Ts … (2 N-2 PE-2 EM(t) PE-M . .. … … Eng. of S/W Pro., India 2009 .. … … SW3 1×2N-2 eD(t) 0×Ts E2(t) ... 1×2N-2 eC(t) PE-1 . .. … SW4 E1(t) (2N-2-1)×Ts e(t) Pe Nm×1 … SW3 … … . .. (2N-2-1)×Ts 1×2N-2 eA(t) Pe-1 0×Ts 0×Ts 31 VPI Simulation Software – Router 32 Simulation Results-Time Waveforms #0 (a) #1 #4 #12 #20 #28 (a) input packet at node A (b) (b) (c) (c) extracted clock at nodes A extracted clock at nodes B FWHM = 2ps #0 #1 #12 Routing Table Conventional RT Single PPM RT Multiple PPM RTs VPI – PPM Multiple Routing Table a4 a3 a2 a1 a0 (N=5) Check MSBs a4 a3 (X=2) a4 a3 =10 a4 a3 =11 a4 a3 =01 a4 a3 =00 a2 a1 a 0 EA (24 – 31) E1A E2A EB (16 – 23) E3A E1B E E2B EC (8 – 15) E3B E1C E E2C ED (0 – 7) E3C E1D E E2D E3D Simulation Results-Multi-hop … #26(11010) #31(11111) … … B A o/p2 … D o/p1 o/p3 #0(00000) #9(01001) o/p2 C … #14(01110) #13(01101) #5(00101) electrical low-speed data packet optical packet edge node core node An optical core network with 32 edge nodes (4 hops) Simulation - Multiple-hop Routing Node/Router 2 Node/Router 2 B 0 1 2 3 4 5 6 M 7 8 9 10 11 12 13 14 15 Node/Router 3 Node/Router 1 Node/Router 1 B B: broadcast M: multicast B M • Signal intensity is varied Node/Router 3 • Noise level is increased 37 SMZ - Simulation Results Inter-channel crosstalk Eng. of S/W Pro., India 2009 Eye diagram Simulation Results – Network Performance Multiple-hop OSNR OSNR1 OSNR0 Source Edge-node # Source G1 Pase ,1 Pin G0 1 L0 Pase ,0 OS G0 L0 Pin 1 L0 Pase ,0 GH Pase ,H G2 Pase , 2 1 L1 OS attn. … 1 LH G0G1G2 L0 L1 Pin G0G1 L0 Pin G1G2 L0 L1 Pase ,0 + G2 L1 Pase ,1 + Pase ,2 G1 L0 Pase ,0 + Pase ,1 G0G1 L0 L1 Pin G1 L0 L1 Pase ,0 + 1 L1 Pase ,1 0 T heoretical, OSNR = 34dB 40 0 T heoretical, OSNR = 40dB 0 Simulation, OSNR 0 = 28dB OSNR (dB) 35 Simulation, OSNR 0 = 34dB 30 Simulation, OSNR 0 = 40dB 25 20 15 10 0 1 # Target HP T heoretical, OSNR = 28dB Eng. of S/W Pro., India 2009 Target Edge-node attn. 45 Predicted & simulated OSNRs 1 LH +1 attn. OS HP HP G0 Pin Pase ,0 OSNRH OSNR2 2 3 Number of hops 4 5 … attn. Attenuator Optical fiber Optical pre-amplifier 1xM All-optical Packet-switched WDM Router PK1@1 PK1@1 PPM-HP 1 PK2@2 e1 PK3@3 ... PKM @L Input PK2@2 D E M U X … … … L … E1 E2 E3 EM PPM-HP 2 e2 … … 1 2 … L PK1@1 PK2@2 WDM MUX WDM Output 1 PKM @L MUX Output 2 ... … E1 E2 E3 EM PKM @L PPM-HP L eM 1 2 … … E1 E2 E3 EM L: The numbers of input wavelengths M: The numbers of the output ports (In this simulation L = 2 and M =3) 1 2 … L WDM MUX Output M Simulation Results- Time Waveforms Packets at the inputs of the WDM router Packets observed at the output 2 of the WDM router Optical OFDM Orthogonal Frequency Division Multiplexing (OFDM) Harmonically related narrowband sub-carriers The sub-carriers spaced by 1/Ts The peak of each sub-carrier coincides with trough of other sub-carriers Splitting a high-speed data stream into a number of low-speed streams Different sub-carrier transmitted simultaneously 42 Applications of OOFDM Modems Access and local area networks - IMDD modems Future high-capacity long-haul networks Coherent modems: Combating optical fibers dispersion and polarization mode dispersion 43 OOFDM Modems - Modelling Matlab: easy to model the OFDM modem 32-QAM modulation 5 4 3 2 1 IMAG 0 -1 -2 -3 -4 -5 -5 -4 -3 -2 -1 0 REAL 1 2 3 32-QAM detectionm with additive noise 4 5 8 6 4 2 IMAG 0 -2 -4 -6 -8 -8 -6 -4 -2 0 REAL 2 4 6 8 44 OOFDM Modems – Modelling VPI Screen shots (OTDM to WDM Transmultiplexers) 45 Software Modelling VPI is not very flexible when it come to modelling algorithm, consequently Matlab code can be used as a part of VPI VPI has visual interface (drag and drop), with the ability to use test and measurement tools Solid mathematical background is essential to fully utilise VPI, otherwise it could lead to misunderstanding and consequently obtaining wrong results 46 It All Starts From An Initial Idea Simulation softwares enables us to develop new ideas & gain some insight before designing systems Output packets Optical Switch Input packets Pout, 1(t) SMZ1 τtot (1-2α)P(t + τtot) Pin(t) Absorber Pout, 2(t) SMZ2 τCEM SMZM αP(t + τCEM) PPM-HEM Pout, M(t) XPPM(t) OSC αc(t) PPRT CEM m1(t) c(t) E1(t) &1 τPPRT e(t) E2(t) EM(t) m2(t) &2 mM(t) &M System block diagram Simulation layout Experimental setup 47 Conclusions What one should look for in simulation software packages in photonic switching network: 1. Easy to learn and use 2. Lower PC hardware specifications 3. Fast and as realistic as possible 4. Quality technical support, training and online discussion forums 5. Updateability 6. Compatibility with other simulation softwares Eng. of S/W Pro., India 2009 48 Special Thanks for Dr. Wai Pang Ng Dr. Hoa Le Minh Dr M F Chaing A. Shalaby M. A. Jarajreh Thank you for your attention ! Any questions? Eng. of S/W Pro., India 2009 50 Future Contact Email: [email protected] Web: http://soe.unn.ac.uk/ocr/ Tel: 00 44 191 227 4902 Eng. of S/W Pro., India 2009 51