Signal-Quality Consideration for Dynamic Connection Provisioning in All- Optical Wavelength-Routed Networks

Transcription

1 Signal-Quality Consideration for Dynamic Connection Provisioning in All- Optical Wavelength-Routed Networks Biswanath Mukherjee Professor of Computer Science, UC Davis Acknowledgement: Yurong (Grace) Huang, Professor Jonathan P. Heritage, Professor Debasish Datta, Professor Byrav Ramamurthy Page 1 Impairment-Aware RWA in Optical Mesh Networks References: 1. Y. Huang, W. Wen, J. P. Heritage, and B. Mukherjee, Signal-Quality Consideration for Dynamic Connection Provisioning in All-Optical Wavelength-Routed Networks, Proc., Opticom '03, Dallas, TX, Oct (for impairment-aware RWA in higher-speed regime). 2. B. Ramamurthy, D. Datta, H. Feng. J.P. Heritage, and B. Mukherjee, Impact of transmission impairments on the teletraffic performance of wavelength-routed optical networks, IEEE/OSA Journal of Lightwave Technology, vol. 17, no. 10, pp , Oct (for impairment-aware RWA in lower-speed regime. 3. B. Ramamurthy, D. Datta, H. Feng, J. P. Heritage, and B. Mukherjee, Transparent vs. opaque vs. translucent wavelength-routed optical networks, Technical Digest, Optical Fiber Communication (OFC '99), San Diego, CA, Paper TuF2, pp. 9-61, Feb (also for lower-speed regime). Page 2 1

2 Outline Introduction Problem statement Impairment-aware routing and wavelength assignment (IRWA) Numerical examples Conclusion Page 3 Introduction Routing and wavelength assignment (RWA) computes a lightpath. A lightpath normally travels through several nodes and fiber spans. Physical components along a lightpath affect network performance by degrading signal quality. Physical impairments become more troublesome in a high-speed network. New techniques are necessary for carrying high-speed data traffic. Dispersion management Promising optical amplifier, e.g., Raman amplification Intelligent RWA algorithm combating impact of impairments Page 4 2

3 Problem Statement: Effects of Transmission Impairments on RWA RWA without impairments consideration is based on an assumption of error-free transmission. Network performance will suffer since transmission impairments can block a lightpath in the physical layer Call setup λ 1 λ noise Call blocked 6 distortion 6 Ideal network Realistic network with impairments Important to consider transmission impairments in RWA! Page Impairment-Aware RWA No Call request Network-Layer Module Look for a candidate lightpath (LP) Good LP quality? Yes Candidate LP no LP available Physical-Layer Module Estimate LP quality Block call OSNR constraint model PMD constraint model Characteristics of our approach Lightpath assignment with signal-quality consideration Consider high-speed impairments Polarization mode dispersion Raman amplifier noise provision signal-qualityguaranteed connections improve resource utilization minimize call-blocking probability Admit call Page 6 3

4 Example Lightpath Configuration Source (0) Intermediate (k-1) k-th hop Intermediate (k) Destination (M) N amplification spans Amplification span (r) SSMF 70 km SSMF 70 km DCF DCF Raman pump 12 km -100 ps/nm/km Raman pump 12 km -100 ps/nm/km ASE Xtalk ASE Polarization mode dispersion (PMD) Noise Amplifier noise: DRA, EDFA Switch crosstalk Receiver noise Page 7 BER-Based Call Admission: Components along a Lightpath Page 8 4

5 Illustrative Example , ,000 1,200 1, , , ,100 1,000 1,200 1, , , , ,000 1, ,000 1,10 1, , , , , Example network topology with fiber length marked on each link 24 nodes 43 bidirectional links 16 λs Wavelength continuity Data rate = 10 Gbps BER threshold = 10-9 Dynamic traffic Poisson arrival Negative-exponential holding time Uniform distributed S-D pair Simulate one million calls Page 9 Results - Blocking Probability (1) Network Impairment-Aware First Fit Ideal network without impairments Realistic network with impairments Impairment-aware RWA (IRWA) (Proposed) 30.4% reduction Reduced blocking by getting feedback from physical layer. Proposed algorithm () performs close to ideal (). Page 10

6 Results Blocking Probability (2) Network Impairment-Aware Best Path Ideal network without impairments Realistic network with impairments Impairment-aware RWA (IRWA) (Proposed) 13.3% improvement Reduced blocking by getting feedback from physical layer. Proposed algorithm () performs close to ideal (). Page 11 Results Computational Complexity Signal-quality estimation procedure is complex, but acceptable! Number of trials increases at low load and decreases at high load. Page 12 6

7 Results Effect of Data Rate 40 Gbps 20 Gbps 10 Gbps 10% 0% 100% Impairment-aware RWA improves blocking probability for different data-rate scenarios. Page 13 Conclusion Network design problems are closely related to physical layer, hence important to incorporate physical-layer information in network-layer design. New impairment-aware RWA algorithms were proposed combating high-speed transmission impairments to effectively reduce network blocking probability. Acceptable computational complexity. Improvement is achieved for different high bit-rate networks. Page 14 7