EFFICIENT ROUTING FOR HYBRID OPTICAL-CDMA AND WDM ALL-OPTICAL NETWORKS

1
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

2
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

3
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)

4
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.

5
IMPAIRMENTS
Class Impairment Constraint
Linear Attenuation (Loss) Optical amplification implying OSNR degradation
Linear Chromatic dispersion (GVD) Compensation fiber or limit on the total length of fiber links
Linear Polarization-mode dispersion (PMD) Total length of fiber links
Non-linear Self-phase modulation (SPM) NLP constraint
Non-linear Cross-phase modulation (XPM) NLP constraint
Non-linear Four Wave Mixing (FWM) Negligible (per system design)
Non-linear Simulation Raman scattering (SRS) Modification of signal power (and thus NLP)
Non-linear Stimulated brillouin scattering (SBS) Negligible
Noise Amplifier spontaneous emission (ASE) OSNR degradation (resulting in constraint on the number of fiber spans)
6
ROUTING ALGORITHM FLOW DIAGRAM
7
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

8
FIBER METRICS
9
SWITCH METRICS CALCULATION
10
SWITCH METRIC CALCULATION
11
SWITCH STRUCTURE
12
FIBER METRIC CACULATION
13
NETWORK UNDER INVESTIGATION
14
BLOCKING PROBABILITY
c represents the bisectional bandwidth (BSBW) a
is the traffic load in Erlang
15
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
16
SYSTEM PARAMETERS OF THE NETWORK
Parameter Value (NW III)
Optical bandwidth (Bo) 50 GHz
Electrical bandwidth (Be) 10 GHz
Signal power per channel 4.77 dBm
Minimum received power (Pmin) -40 dBm
losses (connectors, coupling loss, etc.) 8 dB
Non-linear impairments effect 2 dB
OSNRmin 8.7506 dB ( BER 10-9)
Effective fiber length (Leff) 22 km
Dispersion slope (dDc /d?) 0.07 ps/km.nm2
Insertion loss (Lr) 2.5 dB
Receiver responsitivity ( R ) 1 A/W
Refractive-index (n) 1.48
Shot noise power (Nsh) 1010-14 A/vHz
Thermal noise power (Nth) 10x10-12 A/vHz
Spontaneous emission power (Nspo) 1010-17 A/vHz
Third order nonlinear susceptibility (?1111) 610-15 cm3/erg
17
BLOCKING PROBABILITY WITH/WITHOUT CONSTRAINT
SWITCH
18
AVERAGE COST/CONNECTION
19
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