Design of OPSy (Optical Packet Synchronizer)

1. Design of OPSy(Optical Packet Synchronizer) 20022037 Kim jinah 20032001 Gang kwanwook

2. Introduction • What is OPSy (Optical Packet Synchronizer) ? In an asynchronous optical network system, each transmitter node sends out optical packets asynchronously. The electric control systems for switching these packets at an optical packet switching node(OPSw) are much simpler when incoming packets are aligned in a series of common time slots provided at the OPSw. This alignment call, which is also called packet synchronization, is a key technology for the development of OPSw, and it achieved using an optical packet synchronizers (OPSy).

3. High dispersive fiber High dispersive fiber 2R regeneration Ch 1 2R regeneration Signal(1550nm) Signal(1550nm) circulator circulator 2x2 Switch 2x2 Switch coupler coupler WC WC WC WC DFB LD (1560nm) DFB LD (1540nm) DFB LD (1550nm) DFB LD (1550nm) Ch 2 Proposed Sync. system Fiber Delay Loop

4. Proposed Sync. system • Characteristics of Fiber Delay Loop Advantages - Flexible system : possible to control delay following loop times, otherwise use fixed delay line in other system Disadvantages - It needs two switches and delay lines per one channel : generate crosstalk and signal degradation : use amplifier to compensation - Total latency is high (determine latency following loop numbers) : total times to rotation of signal(ns-us), switching times(~ms)

5. Sync. system algorithm • How’s it proceed Packet signal generation : Random packet generation >> Examine packets : Sorting algorithm >> Delay : If_else statement >> Circulation : For Loop >> pass Loop >>analysis of results (NW socket programing under UNIX circumstance using C++ compiler) • Conditions for Sync. System - How many channel is efficient to satisfy high speed? - Proper range of using wavelength range under physical Fiber Delay Loop - Proper fiber loop length - How many times circulate fiber Loop to align packet synchronously

6. Sync. system condition IEEE Photonic Technology Letter. Sep. 2002 • Time slot & packet format • Time slot : 1024ns • Packet length : 896ns • Guard time : 128ns Packet length (896ns) Time slot (1024ns) Gurad time (128ns)

7. Sync. system algorithm • Misalignment of packet ∆t1 Ch 1 Ch 2 Ch 3 … … ∆tn Ch n

8. Sync. system condition • DCF condition & Delay - DCF condition : Dispersion : -90ps/nm km : Dispersion slope : 0.21ps/nm2km - Delay with optical channel (f0 = 193.1THz)

9. Sync. system algorithm • Wavelength selection • If∆tnis larger than the half of packet length (448ns) • Accelerate signal • 193.6 THz ~ 196. 6 THz • If∆tnis smaller than the half of packet length (448ns) • Delay signal • 192.6 THz ~ 189.6 THz • Packet divided by signal channel (the # of fn) f4 f5 f6 f7 f1 f2 f3 f0 0ns 56ns 112ns 168ns 224ns 280ns 336ns 392ns 448ns

10. Sync. system algorithm • System specification • Time resolution : the half of packet / # of signal channel / 2 • Ex) 448ns/8/2 = 28ns • # of loop circulation : time segment / channel delay • Ex) 56ns/ ~360ps = 155.55555 • Bit rate independent

11. Future works • Program for optimization • DCF condition : Dispersion per length, dispersion slope etc(signal degradation). • Wavelength conversion : Channel spacing, channel range, # of channel etc. • Determine optimized system factor : : # of ch, Loop length, delay time following wavelength. Others…