Download EFFICIENT ROUTING FOR HYBRID OPTICAL

EFFICIENT ROUTING FOR HYBRID OPTICAL-CDMA
AND WDM ALL-OPTICAL NETWORKS
Mehdi Shadaram and Paul Cotae
University of Texas at San Antonio
San Antonio, TX 78249
and
Ahmed Musa, Virgilio Gonzalez, and John Medrano
University of Texas at El Paso
El Paso, TX 79968
IEEE MILCOM Conference
Washington, D.C.
October 23-25, 2006
ECE Department, Photonics Research Laboratory
OUTLINE
• Introduction (Why?)
• Backbone Network
- Optical-Optical-Optical (OOO)
- Optical-Electrical-Optical (OEO)
•
•
•
•
•
•
Routing Benefits and Disadvantages
Proposed Routing Algorithm
Routing (Setup Optimal Lightpath) Steps
Routing Implementation Using Flooding Mechanism
Example
Conclusions
ECE Department, Photonics Research Laboratory
INTRODUCTION
• A high demand for higher capacities because of





Multimedia services
Video conferences
Internet
Environmental Remote Sensing
Medical Imaging
• Approaches to make the transmission medium with a
scalable bandwidth (BW) capacity


Install more fiber (costly)
Exploit the BW of existing fiber using higher data rates
and multiplexing techniques such as
 Wavelength Division Multiplexing (WDM)
 Time Division Multiplexing (TDM)
 Code Division Multiplexing (CDM)
ECE Department, Photonics Research Laboratory
ALL OPTICAL NETWORKS
 Advantages
– Solve the electronic equipment bottleneck
– Exploit the existing network
 Disadvantages
Photonic NW is a complex system ( a large number of
different functions must cooperate for a network such as
–
–
–
–
transmission
Routing and Switching
Control and management
etc.
ECE Department, Photonics Research Laboratory
IMPAIRMENTS
Class
Linear
Nonlinear
Noise
Impairment
Constraint
Attenuation (Loss)
Optical amplification implying OSNR
degradation
Chromatic dispersion (GVD)
Compensation fiber or limit on the total
length of fiber links
Polarization-mode dispersion
(PMD)
Self-phase modulation (SPM)
Total length of fiber links
Cross-phase modulation (XPM)
NLP constraint
Four – Wave Mixing (FWM)
Simulation Raman scattering
(SRS)
Negligible (per system design)
Modification of signal power (and thus
NLP)
Stimulated brillouin scattering
(SBS)
Negligible
Amplifier spontaneous emission
(ASE)
OSNR degradation (resulting in
constraint on the number of fiber spans)
NLP constraint
ECE Department, Photonics Research Laboratory
ROUTING ALGORITHM FLOW DIAGRAM
Call Request
No LP
available
RWCA stands for
Routing Wavelength-Code Assignment
Network - Layer Module
Look for an available
lightpath (LP) using RWCA
Block Call
Yes
Candidate LP
K = 2b -1, b = 24 bits
Wavelength and Code
Assignment
Calculate lightpath (LP) Metric
Fiber Metric
Switch Metric
Physical - Layer Module
Metric > K
No
Admit Call
Calculate LPs Metrics
Choose the best path
(i.e., Min. cost path)
Apply Viterbi algorithm
on the closed loop
Choose the lowest
metric path
ECE Department, Photonics Research Laboratory
ROUTING PROCEDURE
Proposed Routing Algorithm
1.
Use Optical CDM and WDM to label the optical signal
2.
Take into account the physical impairments exist in the NW
3.
Set up the lightpath based on the minimum cost from ingress to egress
node.
Routing (Setup Optimal Lightpath) Steps
First Step :
Calculate the fiber metrics
Second Step :
Calculate switch metrics
Third Step :
Apply Viterbi algorithm on each close loop from
the source to destination to select the minimum metric
ECE Department, Photonics Research Laboratory
FIBER METRICS
I/P Metric
1 2
O/P Metric
l
C1 m11 m12 ....... m1l 
C2 m21 m22 ....... m2l 
 

Ck mk1 mk2
Where
 

 mkl 

1 2
Link merits (L) :Attenuation 
Dispersion D
(o)
M  M(i)  Δ
l
C1  m11' m12' ....... m'1l 
C2  m'21 m'22 ....... m'2l 
 

Ck m'k1 mk2'
 

 m'kl 

Mij'  Mij  Δ , and  is a function of Attenuation  and Dispersion D
ECE Department, Photonics Research Laboratory
SWITCH METRICS CALCULATION
Switch Y
D A
2 xxx
1
λ1C1
λ2C1
λ2
λ2C1
λ2C2
7
λ2
λ2 9
5
7
C1
C1 C2
λ
8 10
1 11
λ
9
7
8
2
λ2C2
1
λ1C2
λ1
3 xxx
1
λ1C1
λ2C1
3
1
1
1
λ2C2
1
Switch Y
2 xxx
8
λ2 9
5
7
C1
C1 C2
8 10 λ1 11
λ2 9
7
8
D A
2 xxx
4
Switch X
λ2C1
λ1C1
λ2C2
1
λ1C1
7
C1 C2
λ1
4
λ1
7
5
λ2
5
7
C1 C2
λ1
8
10
λ2
7
8
C1 C2
λ1
7
λ2
9
7
C1 C2
λ1 11
λ2 9
Min( )
6
7
C2
λ1
λ2
9
8
C1
4
5
C2
5
7
Switch X
1
λ1C1
λ2C1
3
1
1
1
λ2C1
3
4
5
5
λ2C2
1
λ2C2
7
1
λ1C1
λ1C2
Switch # X
C2
5
7
C1 C2
λ2
5
C1
4
5
Switch Y
2x2x2x2
λ1C1
λ1
λ2
9
3
4
4
5
5
λ1C2
7
C2
4
λ2
1
1
λ1C1
Min( )
6
λ1
λ1
3
1
1
1
1
λ1C1
7
C1 C2
5
7

λ1C2
D A
5
2
λ1C2
Switch Y
D A
λ1
4
λ2C1
λ2C2
C1 C2
λ1
1
λ1C1
λ1C1
C1 C2
2
4
5
5
3
1
1
1
λ1C2
3
IP1  
6
Switch X
λ1C2
Min( )
6
9
8
λ1
λ2
C1
4
5
C2
5
7
ECE Department, Photonics Research Laboratory
SWITCH METRIC CALCULATION
M  M   M c  M Ocupation  
ECE Department, Photonics Research Laboratory
SWITCH STRUCTURE
ECE Department, Photonics Research Laboratory
FIBER METRIC CACULATION
L
L
 L


) * K/N , If L  L
, LL
and L  L
( L
atten.
GVD
PMD
M i, j   atten. LGVD L PMD

, Otherwise
K

L
L
1 

, If the fiber is dipersion - limit
L
L

atten
PMD

L
L

N  1 

, If the fiber is attenuatio n - limit
L
L

GVD
PMD

L
L
1 

, If the fiber is PMD - limit

L
L
atten
GVD

ECE Department, Photonics Research Laboratory
NETWORK UNDER INVESTIGATION
Switching Point
(Signal transfer Point)
2
1
3
4
6
5
S #2
F1
4
5
2
F5
3
Bisectional
Bandwidth
3
4
S #4
2
6
1
S #1
F3
5
1
6
F4
F2
1
6
S #3
2
3
External node
5
Photonic switch
4
Fiber link
Signaling link
ECE Department, Photonics Research Laboratory
BLOCKING PROBABILITY
c
a
P[all c channels are busy]  B(c, a)  c c! k
a

k  0 k!
c represents the bisectional bandwidth (BSBW)
a is the traffic load in Erlang
j  k  number of links across the plane
c
2
ECE Department, Photonics Research Laboratory
TRAFFIC PARAMETERS
Channel speed (CS)
2.5 Gbps
Average data size for a call (DataSize)
600MB
Number of switches ( S )
4
Number of wavelengths in each switch
4 (1551.72, 1552.52,
1553.33, and 1554.13 nm)
Number of codes in each switch
4
Bisectional bandwidth (BSBW)
48
Number of tested calls per scenario
20,000
ECE Department, Photonics Research Laboratory
SYSTEM PARAMETERS OF THE
NETWORK
Parameter
Value (NW III)
Optical bandwidth (Bo)
Electrical bandwidth (Be)
Signal power per channel
Minimum received power (Pmin)
losses (connectors, coupling loss, etc.)
Non-linear impairments effect
OSNRmin
Effective fiber length (Leff)
Dispersion slope (dDc /d)
Insertion loss (Lr)
Receiver responsitivity ( R )
Refractive-index (n)
Shot noise power (Nsh)
Thermal noise power (Nth)
Spontaneous emission power (Nspo)
Third order nonlinear susceptibility (1111)
50 GHz
10 GHz
4.77 dBm
-40 dBm
8 dB
2 dB
8.7506 dB ( BER = 10-9)
22 km
0.07 ps/km.nm2
2.5 dB
1 A/W
1.48
10*10-14 A/√Hz
10x10-12 A/√Hz
10*10-17 A/√Hz
6*10-15 cm3/erg
ECE Department, Photonics Research Laboratory
BLOCKING PROBABILITY WITH/WITHOUT CONSTRAINT
SWITCH
60%
Unifrom
50%
Ideal Switch_Impaired Fiber
Blocking Probability (%)
Impaired Switch_Ideal Fiber
Impaired
40%
Impaired with no conversion
30%
20%
10%
0%
0
20
40
60
80
100
120
140
160
180
200
220
Traffic
Load (Erlang)
ECE
Department,
Photonics Research Laboratory
AVERAGE COST/CONNECTION
10,800,000
Ave Metric (Cost) / Connection
10,600,000
10,400,000
PA
10,200,000
FWMDP
10,000,000
9,800,000
9,600,000
9,400,000
9,200,000
9,000,000
0
20
40
60
80
100
120
140
160
180
200
220
Traffic Load (Erlang)
ECE Department, Photonics Research Laboratory
SUMMARY
• A fundamental understanding of the basic
routing techniques and the factors that
influence their behavior is critical in designing
and selecting appropriate routing strategies
for a network
• To alleviate the routing complexity, different
optimization methodologies are proposed
• Better utilization of the network resources can
be achieved when the impairments in the
network are taken into consideration in the
routing algorithm
ECE Department, Photonics Research Laboratory