Transcript m11

Design of OPSy
(Optical Packet Synchronizer)
20022037 Kim jinah
20032001 Gang kwanwook
ICE 541 Concrete Mathematics
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).
ICE 541 Concrete Mathematics
Proposed Sync. system
Fiber Delay Loop
High dispersive fiber
2R regeneration
Ch 1
Signal(1550nm)
2x2 Switch
circulator
coupler
2R regeneration
WC
WC
DFB LD (1540nm)
DFB LD (1550nm)
High dispersive fiber
Ch 2
Signal(1550nm)
2x2 Switch
circulator
coupler
WC
DFB LD (1560nm)
WC
DFB LD (1550nm)
ICE 541 Concrete Mathematics
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)
ICE 541 Concrete Mathematics
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
ICE 541 Concrete Mathematics
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)
ICE 541 Concrete Mathematics
Sync. system algorithm

Misalignment of packet
∆t1
Ch 1
Ch 2
Ch 3
…
…
∆tn
Ch n
ICE 541 Concrete Mathematics
Sync. system condition

DCF condition & Delay
- DCF condition
: Dispersion : -90ps/nm km
: Dispersion slope : 0.21ps/nm2km
- Delay with optical channel (f0 = 193.1THz)
Channel
Delay(ps)
Channel
Delay(ps)
192.6
362
193.6
-362
192.1
722
194.1
-725
191.6
1085
194.6
-1094
191.1
1443
195.1
-1462
190.6
1800
195.6
-1834
190.1
2145
196.1
-2201
189.6
2496
196.6
-2576
ICE 541 Concrete Mathematics
Sync. system algorithm

Wavelength selection
If ∆tn is larger than the half of packet length (448ns)



Accelerate signal
193.6 THz ~ 196. 6 THz
If ∆tn is smaller than the half of packet length (448ns)



Delay signal
192.6 THz ~ 189.6 THz
Packet divided by signal channel (the # of fn)

f1
f2
f3
f4
f5
f6
f7
56ns
112ns
168ns
224ns
280ns
336ns
392ns
f0
0ns
ICE 541 Concrete Mathematics
448ns
Sync. system algorithm

System specification

Time resolution : the half of packet / # of signal channel / 2


# of loop circulation : time segment / channel delay


Ex) 448ns/8/2 = 28ns
Ex) 56ns/ ~360ps = 155.55555
Bit rate independent
ICE 541 Concrete Mathematics
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…
ICE 541 Concrete Mathematics