cost action 272 capacity dimensioning of intersatellite ... · m1 m2-reduced m2-standard...

COST Action 272“Packet-Oriented Service Delivery via Satellite”

Capacity Dimensioning of Intersatellite Linksin Constellation Networks Using Optical WDM Networking

TD-01-___-S

Daniel Ratto Gómez , Markus WernerGerman Aerospace Center (DLR)

Institute of Communications and [email protected]

Capacity Dimensioning of Intersatellite Links in Constellation Networks Using Optical WDM Networking

D. Ratto Gómez, M. Werner COST 272 1st MCM Toulouse, 11-12 Oct. 2001 1

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Introduction: Introduction: Optical Transport Network (OTN)Optical Transport Network (OTN)

λ1λ2

λ3

WDM ISL��λ1, λ1, λ1�

Objectives:Objectives:

• Simplify the routing.

• Reduce queuing delays at someintermediates nodes.

• Reduce the processing load forthe on-board processor.

• The OTN is formed by assigning separate wavelength channelsto dedicated pairs of satellites and one (or more) continouspath(s) between them, so-called LigthPath.




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The OTN TopologyThe OTN Topology

Optical swich node

Origin and destination nodes

Processing node

• Origin-Destination Connection• LightPath• Inter-Satellite Link

Optical switch node


Processing node

Sat A

Sat B

Destination Satellite

First Lightpath

Second Lightpath

λ1

λ2

λ3

Wavelength-Division Multiplexing

The same wavelength (Lightpath)could be used if different routeshave the same destination satellite

On-board Wavelength Routing


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• Multiple-Hop Logical Connectivity

Connectivity and Technology OptionsConnectivity and Technology Options

Optical switch node


Processing nodeOrigin SatelliteA


Origin SatelliteB

• Single-Hop Logical Connectivity

• Double-Hop Logical Connectivity• Dedicates a completewavelength to each Origin-Destination connection (i.e.Lightpath).




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• Double-Hop Logical Connectivity

Optical switch node


Processing node

Origin Satellite


• Reduction number of wavelengths.

• Imperative in large constellations.

• Reuses wavelengths.


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• Double-Hop Logical Connectivity

Optical switch node


Processing node

Origin Satellite


• Particular case of MH-Connectivity.

• It maintains a high degree of connectivityat optical level.

• Increase of the network resourcesutilization.

• Reduce the number of maximumwavelengths per ISL.




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Routing SelectionRouting Selection

Objectives::

• To increase the network resources utilization splitting the traffic.

• To choose the shortest paths to reduce the queuing, routing,

switching and propagation delays.

• Use the regular structure of satellite network.


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•• Deterministic Routing Selection Deterministic Routing Selection

• Optimized Routing Selection

• M1 - Approach

• M2 - Approach

• Full Optimization

Route

Origin Satellite

Destin Satellite

Intermediate nodes


• Use “Matrix-route“ (theshortest route) for the wholeOrigin-Destination traffic.




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•• Deterministic Routing Selection Deterministic Routing Selection

• Optimized Routing Selection

• M1 - Approach

• M2 - Approach


First route

Origin Satellite

Destin Satellite

Intermediate nodes


Mirror route

• A “Mirror Route“ is used tosplit the whole traffic in apercentage 50%:50% (Equalsharing).


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• Deterministic Routing Selection

•• Optimized Optimized Routing Selection Routing Selection

• M1 - Approach

• M2 - Approach


First route

Origin Satellite

Destin Satellite

Intermediate nodes


Second route

Third route

• The shortest-hop group for eachOrigin-Destination traffic is used.

• The optimizer finds an optimumsharing traffic between the routes.




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Routing in Optical Satellite NetworksRouting in Optical Satellite Networks

Alternate Path (The Mirror Route for M2 - Approach)Alternate Path (The Mirror Route for M2 - Approach)

• M2 - Reduced Approach

• M2 - Standard Approach

• M2 - Extended Approach

1 3 42 n-2 n-1 nPLANES

RINGS

1

2

j

i

m-1

m

First route

Mirror route

Origin Satellite


• If the number ofintermediate nodes is largerin the Mirror Route, only thefirst route is used.


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RINGS

1

2

j

i

m-1

m

First route

Mirror route

Origin Satellite







• First Route and MirrorRoute are disjoint.




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RINGS

1

2

j

i

m-1

m

First route

Mirror route

Origin Satellite







• Neighbour satellites areused as Mirror Route.

• Double-Hop connectivityis not viable.


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Constellations under StudyConstellations under Study

• The constellations under study :

• MeonetMeonet : - Walker Constellation 15 / 3 / 1 - Inclination 54°

- MEO Constellation

• CelestriCelestri : - Walker Constellation 63 / 7 / 5 - Inclination 48°

- LEO Constellation

• Both are Delta-constellations toavoid the seam edge.

• Inter-orbit links permanentlyavailable.




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Traffic ScenariosTraffic Scenarios

1 11

1 1 12 2 23 3 3

OD Traffic OD Traffic OD Traffic

T1 T2 T3

pdf (OD Traffic) pdf (OD Traffic)pdf (OD Traffic)

1/2

• Generic scenarios (Bidirectional and Symmetric traffic):

• T1 : Deterministic traffic.• T2 : Traffic with uniform distribution.• T3 : Decreasing traffic distribution.

• “Realistic“ traffic:

• T4

• T5


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Traffic ScenariosTraffic Scenarios

• Generic scenarios :

• T1• T2• T3

• “Realistic“ traffic: Traffic generation depending on terrestrialparameters.

• T4 : Smooth distributed traffic on the Earth.

• T5 : Peaky traffic in some specific zones on the Earth.

Ground Traffic Intensity




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ResultsResults

Worst Case Intra-link Load

0

20

40

60

80

100

120

140

160

180

T1 T2 T3 T4 (EqualSharing)

T5 (EqualSharing)

T4 (MaxElev.)

T5 (Max.Elev.)

Traffic Scenario

Tra

ffic

(c.

u.)

M1 Approach M2-Reduced (Equal Sharing) M2-Standard (Equal Sharing)

M2-Extended (Equal Sharing) M2-Extended (Full Optimization)

• The worst case link load is drastically reduced combining M2approach, single-hop and the optimizer.


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ResultsResults

Worst Case Inter-link Load

0

20

40

60

80

100

120

140

160

T1 T2 T3 T4 (EqualSharing)

T5 (EqualSharing)

T4 (MaxElev.)

T5 (Max.Elev.)

Traffic Scenario

Tra

ffic

(c.

u.)

M1 Approach M2-Reduced (Equal Sharing) M2-Standard (Equal Sharing)

M2-Extended (Equal Sharing) M2-Extended (Full Optimization)

• The optimizer uniforms the traffic between intra-links and inter-links.




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ResultsResults

• Comparison of M2 approaches.

M1 M2-Reduced M2-Standard M2-Extended

max # bidirect. LPs/intra-ISL (single-hop) 9 18 19 21

max # bidirect. LPs/inter-ISL (single-hop) 5 10 14 12

total # of LPs/network 105 210 210 210

max # bidirect. LPs/intra-ISL (double-hop) 3 3 5 5

max # bidirect. LPs/inter-ISL (double-hop) 1 1 3 3

Worst case alter. path delay in close sat. 0 85ms 332ms 295ms

• M2 Reduced gives a better delay and reduces the number of Lightpathsper ISL.

• M2 Standard and M2 Extended give a better traffic distribution.


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ResultsResults

• Comparison of M2 Standard (equal sharing) and M2 Standard(full optimization).

T1 T2 T3 T4 (ES) T5 (ES) T4 (ME) T5 (ME)

WCL load, max 9,5 14,63 17,15 34,2 66,7 34,2 66,7ISL load, mean 9,5 9,33 9,45 9,3 9,8 9,2 9,8average ISL utilization (no OTN) 100,00% 63,77% 55,10% 27,19% 14,69% 26,90% 14,69%

WCL load, max 8 9,01 9,4 22,5 29,86 24,67 36,23ISL load, mean 8 8,09 7,47 7,88 4,54 6,2 5,24average ISL utilization (no OTN) 100,00% 89,79% 79,47% 35,02% 15,20% 25,13% 14,46%

Routing Approach - M2 Standard FO (Full Optimization)

Routing Approach - M2 Standard

Space-based traffic scenario Ground-based traffic scenario




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ConclusionsConclusions

• Some different kinds of alternative routing have beencompared. The selection depends of the network design.

• Combining the optimizer and M2 approach gives us largebenefits.

• It seems interesting to join in the future the optimizer, M2approach and double-hop optical connectivity to get a betterresults.

cost action 272 capacity dimensioning of intersatellite ... · m1 m2-reduced m2-standard...

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