1 PHYSICAL IMPAIRMENTS Maruthy Mentireddi Raghu Kalyan Anna.
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Transcript of 1 PHYSICAL IMPAIRMENTS Maruthy Mentireddi Raghu Kalyan Anna.
1
PHYSICAL IMPAIRMENTS
Maruthy MentireddiRaghu Kalyan Anna
MOTIVATION
IDEALISTIC: NO TRANSMISSION IMPAIRMENTS BEING CONSIDERED IN ROUTING DECISIONS.
REALISTIC: TRANSMISSION IMPAIRMENTS ARE CONSIDERED IN ROUTING DECISIONS.
IN ANY GIVEN SCENARIO TRANSMISSION IMPAIRMENTS PLAY A MAJOR ROLE IN ROUTING.
AGENDA
• TRANSMISSION IMPAIRMENTS• IMPAIRMENTS BEING CONSIDERED• METRICS AND NETWORK COMPONENTS DESCRIPTION• HYBRID SIMULATION TECHNIQUE• EVALUATION• IMPAIRMENT AWARE RWA • CONSTRAINT MODELS• ILLUSTRATIVE EXAMPLES• ACKNOWLEDGEMENT• BIBLIOGRAPHY
TRANSMISSION IMPAIRMENTS
• LINEAR:– AMPLIFIER NOISE– PMD– CROSSTALK
• NON LINEAR– FOUR WAVE MIXING– SELF PHASE
MODULATION– CROSS PHASE
MODULATION– SCATTERING
IMPAIRMENTS BEING CONSIDERED
• OPTICAL SIGNAL - CROSSTALK AT CROSSCONNECT SWITCHES(XCS) - AMPLIFIED SPONTANEOUS EMISSION (ASE) NOISE AT INTERMEDIATE AMPLIFIERS
Eg., EDFA’S
CONSIDERATIONS FOR CONNECTION PROVISIONING
• OPTICAL SIGNAL-TO-NOISE RATIO (OSNR)• POLARIZATION MODE DISPERSION (PMD)
INTRODUCTORY TERMS
• LIGHTPATH – AN ALL OPTICAL WDM CHANNEL BETWEEN ANY TWO NODES
• CONNECTION PROVISIONING – SETTING UP A LIGHTPATH FOR A CONNECTION REQUEST BY USING A ROUTING AND WAVELENGTH ASSIGNMENT (RWA) TECHNIQUE
• ROUTE – A PATH CONSISTING OF ONE OR MORE FIBER LINKS, FROM THE SOURCE TO THE DESTINATION.
• TRAFFIC/ NETWORK PERFORMANCE: CALL BLOCKING PROBABILITY
• SIGNAL QUALITY: BIT ERROR RATE
METRICS
BLOCKING PROBABILITY
NUMBER OF BLOCKED CALLS Pb = ----------------------------------------------- TOTAL NUMBER OF OFFERED CALLS
BIT ERROR RATE (BER)
ACCUMULATION OF ASE NOISE AND CROSSTALK1
SNR DEGRADATION
INCREASE IN BER2
1 AT EVERY NODE
2 AT DESTINATION
NETWORK COMPONENTS
WRN – WAVELENGTH ROUTING NODE
NETWORK COMPONENTS ALONG A LIGHTPATH IN A WAVELENGTH-ROUTED OPTICAL NETWORK
RECEIVER ARRAY
FIBER LINKCROSS CONNECT
OPTICAL
TAP
TRANSMITTER ARRAY
OPTICAL
AMPLIFIER
NETWORK COMPONENTS (CONTD)
COMPONENTS AND THEIR LOSS/GAIN PARAMETERS IN A WRN
FIBER LOSS
OPTICAL TAP
LOSS
INPUT AMPLIFIER GAIN
OUTPUT AMPLIFIER GAIN
DEMUX LOSSMUX LOSS
SWITCH LOSS
NETWORK COMPONENTS (CONTD)
ARCHITECTURE OF A N x N NONBLOCKING SPACE SWITCH USED IN OUR MODEL
SIMULATION MODEL
HYBRID SIMULATION TECHNIQUE
TRAFFIC VARIATION
CROSSTALK, GAIN, ASE NOISE
AFFECTS BER ESTIMATE
ONLINE BER ESTIMATE
CALL ADMISSION:
- MINIMUM BER
- BER THRESHOLD (SAY 10-12)
CALL ADMISSION
ONLINE BER EVALUATION
BER MODEL
LIGHTWAVE RECEIVED ER(t) = Acos(2ΠVit + Φ(t)) + Ext(t) + Ease(t) PHOTOCURRENT GENERATED ip(t) = Rƛ(ER
2(t)) + ish(t) + ith(t) BER MINIMIZATION σ0Is1
ITH = ------------------ σ0 + σ1
ILLUSTRATIVE EXAMPLES
CALLS AT THE INSTANT OF SIMULATION SNAPSHOT IN A BIDIRECTIONAL RING NETWORK
ILLUSTRATIVE EXAMPLES (CONTD)
PROGRESS OF TAGGED CALL IN A BIRECTIONAL RING NETWORK
ILLUSTRATIVE EXAMPLES (CONTD)
A MESH NETWORK
ILLUSTRATIVE EXAMPLES (CONTD)
MESH NETWORK - BLOCKING PROBABILITY Vs LOAD
FIRST FIT BER
FIRST FIT BER
RANDOM BER
RANDOM BER
INCREASED CROSSTALKINADEQUATE
SATURATION GAIN
IDEAL CASE
FIRST FIT IDEAL
RANDOM IDEAL
IMPLICATIONS• REALISTIC BER: MORE ACCURATE MEASURE OF PERFORMANCE THAN IDEAL CASE
• FIRST FIT BETTER THAN RANDOM FIT (IDEAL)
• RANDOM FIT BETTER THAN FIRST FIT (REALISTIC)
IMPAIRMENT AWARE RWA
WHY IRWA?
AUTOMATICALLY PROVISION A SIGNAL-QUALITY-GUARANTEED LIGHTPATH FOR A CONNECTION REQUEST
IRWA (CONTD)
• LIGHTPATH ASSIGNMENT BASED ON IRWA:
LIGHTPATH COMPUTATION LIGHTPATH VERIFICATION
• NETWORK-RESOURCE BLOCKING : NO AVAILABLE ROUTE OR WAVELENGTH
• PHYSICAL LAYER BLOCKING SIGNAL-QUALITY REQUIREMENTS
IRWA – INTEGRATED MODEL
NETWORK LAYER MODULE
• IMPAIRMENT AWARE BEST PATH ALGORITHM(IABP) • IMPAIRMENT AWARE FIRST FIT ALGORITHM(IAFF)
- WILL RANDOM-ROUTING PERFORM BETTER ?
IABP – INTEGRATED MODEL
• INPUTS - NETWORK STATE
- CONNECTION REQUEST
• OUTPUTSNETWORK LAYER - PATH, WAVELENGTH PHYSICAL LAYER – LIGHTPATH SIGNAL QUALITY
• ALGORITHM- PATH COMPUTATION- PATH OPTIMIZATION / WAVELENGTH ASSIGNMENT- SIGNAL QUALITY ESTIMATION- PATH SETUP- NETWORK STATE UPDATE
PHYSICAL LAYER MODULE• OSNR AND PMD CONSTRAINTS • PMD CONSTRAINT MODEL – TRANSMISSION LENGTH LIMITATION
• OSNR CONSTRAINT MODEL – Q FACTOR AS INTERMEDIATE
LIGHTPATH ARCHITECTURE• AMPLIFICATION SPAN• STANDARD SINGLE MODE FIBER• DISPERSION COMPENSATING FIBER
OSNR ESTIMATION
PROPOSED IRWA’s CHARCTERISTICS
• CONNECTION ADMISSION METRICS: FREE RESOURCES AND SIGNAL QUALITY
• AUTO-PROVISIONING
• IMPAIRMENT AWARENESS - PMD TOLERATION - PRE-ESTIMATED OSNR
• ALGORITHM COMPARISION SCHEMES - NETWORK MODEL: IDEAL AND REALISTIC IDEAL: TRADITIONAL RWA (TBP OR TFF) – A REALISTIC: TRADITIONAL RWA (TBP OR TFF) – B, IRWA (IRWA OR IAFF) – C
BEST-PATH ALGORITHMS
ILLUSTRATIVE EXAMPLES
TBP - REAL
IABP - REAL
TBP - IDEAL
FIRST-FIT ALGORITHMS
ILLUSTRATIVE EXAMPLES (CONTD)
TFF - REAL
IAFF - REAL
TFF - IDEAL
ILLUSTRATIVE EXAMPLES (CONTD)
BEST-PATH ALGORITHMS
EMPLOYING EDFA
TBP - REAL
IABP - REAL
TBP - IDEAL
ILLUSTRATIVE EXAMPLES (CONTD)
FIRST-FIT ALGORITHMS
EMPLOYING EDFATFF - REAL
IAFF - REAL
TFF - IDEAL
ILLUSTRATIVE EXAMPLES (CONTD)
EFFECT ON DATA RATE
AVERAGE NUMBER OF TRIALS FOR SIGNAL-QUALITY ESTIMATION PER CALL
IABP
IAFF
ILLUSTRATIVE EXAMPLES (CONTD)
EFFECT ON DATA RATE
EFFECT OF CHANNEL BIT RATE ON ALGORITHMS IN A REALISTIC NETWORK
IMPLICATIONS• BIT RATE INCREASE MAKES IMPAIRMENTS DOMINANT
• HIGH DATA RATE -> HIGH OSNR IS REQUIRED
• HIGH DATA RATE-> PMD LIMITING FACTOR
ACKNOWLEDGEMENT
FIGURES AND EQUATIONS HAVE BEEN ADOPTED FROM:
1. Impact of transmission impairments on the teletraffic performance of wavelength-routed optical networks, B. Ramamurthy, D. Datta, H. Feng, J. P. Heritage, and B. Mukherjee 2. Connection provisioning with transmission impairment consideration in optical WDM networks with high-speed channels, Yurong Huang Heritage, J.P. Mukherjee, B.,
BIBLIOGRAPHY• Issues for routing in the optical layer, J. Strand, A. L. Chiu, and R. Tkach
• Optical components for WDM lightwave networks,Borella, M.S. Jue, J.P. Banerjee, D. Ramamurthy, B. Mukherjee, B.
• Impact of transmission impairments on the teletraffic performance of wavelength-routed optical networks, B. Ramamurthy, D. Datta, H. Feng, J. P. Heritage, and B. Mukherjee • Connection provisioning with transmission impairment consideration in optical WDM networks with high-speed channels, Yurong Huang Heritage, J.P. Mukherjee, B.,
QUERIES
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