October 2009, CCSDS Fall Meeting at ESTEC 1

JAXA’s DTN activity

Kiyohisa Suzuki

JAXA

October 2009, CCSDS Fall Meeting at ESTEC 2

Computer Simulation for DTN network Feasibility study for NASA-JAXA DTN

Experiments on ISS

Contents

October 2009, CCSDS Fall Meeting at ESTEC 3

Computer Simulation for DTN network

Purpose To learn and accumulate the knowledge of DTN

specification and function toward future spacecraft communication.

To carry out a feasibility study on the capability for End-to-End spacecraft communication network which implemented DTN node.

October 2009, CCSDS Fall Meeting at ESTEC 4

Simulation tools & Scenario Simulation Tools (full software and using COTS)

OPNET To implement protocols To create network topology To calculate AOS/LOS judgment in each tracking station.

STK To calculate satellite orbit

Simulation Scenario LEO satellite network (DTE) DTN Gateway Node on LEO satellite,

Operation Center,each tracking station.

Probability oscillation for loss of frames or packets

To calculate transmission time, loss of frames , number of retransmission ,etc

Static IP routing Network Operation center decides

destination of grand station by FD data

Computer Simulation for DTN network

October 2009, CCSDS Fall Meeting at ESTEC 5

Computer Simulation for DTN network

Building simulation model Implemented

DTN BP (with custody transfer) UDP IP CCSDS encapsulation CCSDS COP-1 CCSDS TC/AOS RF bandwidth

Not Implemented DTN Convergence Layer Bundle security CCSDS Space link channel

coding RF character (modulation, polarization etc)

Specifications

Bundle Protocol Specification RFC5050

User Datagram Protocol RFC768

Internet Protocol RFC791

Encapsulation service CCSDS 133.1-B-1

TC Space Link Protocol CCSDS 232.0-B-1

AOS Space Link Protocol * CCSDS 732.0-B-2

Communications Operation Procedure-1 CCSDS 232.1-B-1

* Only for Downlink

October 2009, CCSDS Fall Meeting at ESTEC 6

• Samples of simulation node model

Spacecraft Onboard design Node design

“DTN Client Node”

“DTN Gateway Node”

Computer Simulation for DTN network

October 2009, CCSDS Fall Meeting at ESTEC 7

Computer Simulation for DTN network

Findings DTN on LEO satellite network has the high certainty for data

transfer in the aspect of QOS. To apply DTN technology to satellite communication, DTN BP specification(RFC 5050) and/or specifications of

peripheral technology will need additional specs. Routing algorithm The flow control of different bandwidth between ground

internet and RF link DTN needs to be considered assignment between DTN BP

and lower layer’s identification. Because Space Link Protocol can define the services each VC.

JAXA did not implemented DTN convergence Layer in current simulation’s stack. We believe some issues are solved by DTN CL.

October 2009, CCSDS Fall Meeting at ESTEC 8

Loss Rate[%]

Delivery Rate [%]

Overlap Bundle Count

Dest. Not RevievedBundle packet Count

Frame 0.0 *1 100.0 0 0

Frame 0.003 *1 100.0 0 0

Frame 0.3 *1 100.0 2 0

Packet 0.1 *2 100.0 18 0

Loss Rate[%]

Delivery Rate [%]

Overlap Bundle Count

Dest. Not RevievedBundle Count

Frame 0.0 *1 100.0 0 0

Frame 0.003 *1 100.0 0 0

Frame 0.3 *1 100.0 0 0

Packet 0.1 *2 99.7 0 43

*1 Frame loss between satellite and ground station*2 IP packet loss in internet cloud at ground

Custody DIS (UDP/IP over CCSDS)

Custody ENA

• Custody has the high certainty

for data transfer in the aspect of QOS.

• Destination DTN node received same context of BP (overlapped) caused by retransmission.

Computer Simulation for DTN network

October 2009, CCSDS Fall Meeting at ESTEC 9

Computer Simulation for DTN network

Frame LossRetransmit

“RFC5050”did not define

routing algorithm

Routing

Simulation results indicated to arise congestion and many retransmitting.

Flow Control

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Routing issuesBP sent after one revolution

Sample of BP behavior with Custody transfer (Uplink)

Computer Simulation for DTN network

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Feasibility study for NASA-JAXA DTN Experiments on ISS

JAXA started the feasibility study for DTN experiments on ISS – DRTS(Data Relay Test Satellite) with NASA.

Firstly, feasibility study focused as follows; Connectivity discussion about

considered route. ISS programmatic things

JAXA conducted technical meetings Aug. 2009 with NASA.

JAXA continues internal technical and administrative coordination.

October 2009, CCSDS Fall Meeting at ESTEC 12

Fin

October 2009, CCSDS Fall Meeting at ESTEC 13

Typical Parameters

Typical Parameters

Bundle

Fragment enabled

Fragment Size (octet) 980

Dictionary Size (octet) 32

Bundle Buffer Size infinity

Custody Signal Wait Time (sec) 60

Lifetime (sec) 50,000

Custody Transfer ENA/DIS

interval BP transfer 1,8,16,32 sec/apprication

TC/AOS

Maximum Transfer Frame Length (octets) 1024

Service Type AD

COP-1

Sliding Window Width 8

CLCW reporting period (sec) 1

Time Timer (sec) 12

Transmission Limit 2

October 2009, CCSDS Fall Meeting at ESTEC 14

BP behavior with Custody transfer (downlink)

0

1000

2000

3000

4000

5000

0 10000 20000 30000 40000 50000 60000 70000 80000

Tra

nsm

issi

on

Tim

e(s

ec)

Total Simulation time(sec)

DTN Bundle Transmission Time

Frame Loss 0%

Frame Loss 0.003%

Frame Loss 0.3%

Packet Loss 0.1%

Computer Simulation for DTN network

October 2009, CCSDS Fall Meeting at ESTEC 15

• Samples of State transition diagram in protocol view

DTN BP

CCSDS AOS

CCSDS COP-1

Computer Simulation for DTN network