1. CCSDS Fall Meeting at ESTEC
JAXA’s DTN activity
Kiyohisa Suzuki
JAXA
October 2009,
CCSDS Fall Meeting at ESTEC

2. CCSDS Fall Meeting at ESTEC
Contents
Computer Simulation for DTN network
Feasibility study for NASA-JAXA DTN Experiments on ISS
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. Computer Simulation for DTN network
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
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 B-1
TC Space Link Protocol
CCSDS B-1
AOS Space Link Protocol *
CCSDS B-2
Communications Operation Procedure-1
CCSDS B-1
* Only for Downlink
October 2009,
CCSDS Fall Meeting at ESTEC

6. CCSDS Fall Meeting at ESTEC
Computer Simulation for DTN network
Samples of simulation node model
Spacecraft
Onboard design
Node design
“DTN Client Node”
October 2009,
CCSDS Fall Meeting at ESTEC
“DTN Gateway Node”

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. CCSDS Fall Meeting at ESTEC
Computer Simulation for DTN network
Custody DIS (UDP/IP over CCSDS)
Loss Rate
[%]
Delivery Rate [%]
Overlap Bundle Count
Dest. Not Revieved
Bundle Count
Frame 0.0 *1
100.0
Frame *1
Frame 0.3 *1
Packet 0.1 *2
99.7 43
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.
Custody ENA
Loss Rate
[%]
Delivery Rate [%]
Overlap Bundle Count
Dest. Not Revieved
Bundle packet Count
Frame 0.0 *1
100.0
Frame *1
Frame 0.3 *1 2
Packet 0.1 *2 18
*1 Frame loss between satellite and ground station
*2 IP packet loss in internet cloud at ground
October 2009,
CCSDS Fall Meeting at ESTEC

9. Computer Simulation for DTN network
Flow Control
Routing
Simulation results indicated to arise congestion and many retransmitting.
Retransmit
Frame Loss
“RFC5050”did not define
routing algorithm
October 2009,
CCSDS Fall Meeting at ESTEC

10. Computer Simulation for DTN network
Sample of BP behavior with Custody transfer (Uplink)
Routing issues
BP sent after one revolution
October 2009,
CCSDS Fall Meeting at ESTEC

11. 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 with NASA.
JAXA continues internal technical and administrative coordination.
October 2009,
CCSDS Fall Meeting at ESTEC

12. CCSDS Fall Meeting at ESTEC
Fin
October 2009,
CCSDS Fall Meeting at ESTEC

13. CCSDS Fall Meeting at ESTEC
Typical Parameters
October 2009,
CCSDS Fall Meeting at ESTEC

14. CCSDS Fall Meeting at ESTEC
Computer Simulation for DTN network
BP behavior with Custody transfer (downlink)
October 2009,
CCSDS Fall Meeting at ESTEC

15. CCSDS Fall Meeting at ESTEC
Computer Simulation for DTN network
Samples of State transition diagram in protocol view
DTN BP
CCSDS COP-1
CCSDS AOS
October 2009,
CCSDS Fall Meeting at ESTEC