the ccsds cislunar communications architecture keith scott the mitre corporation ccsds meeting...
TRANSCRIPT
The CCSDS Cislunar Communications
ArchitectureKeith Scott
The MITRE Corporation
CCSDS MeetingJanuary 2007
Agenda
• CCSDS Cislunar Space Internetworking Working Group Scope and Charter
• Current Mission Architecture• Future Mission Scenarios• Networked Communications• Terrestrial Interoperability
CCSDS Cislunar Space Internetworking Working Group
• Chartered to produce a communications architecture for cislunar (between the Earth and the Moon) communications– Includes robotic Earth-observing and lunar missions
– Includes crewed Earth-orbital and lunar missions
– Where possible, should extend to comparable in-situ environments
SEL2
Limit of Earth-centered Cislunar range for this study.
Sunward
moon
Deimos
Phobos
10 sec. RTTLimit of Mars-centered Cislunar range for this study.
EML2
EML1
10 sec. RTT
0.38s RTT
0.43s RTT
< 0.05 sec. RTT
Sunward
SML2
6.66 sec. RTT
2.5 sec. RTT
Deep Space
Communications
CislunarCommunications
CislunarCommunications
Mars-Specific Communications
~10s RTT
~10s RTT
Current Mission Architecture
RF
1553
Inst Subsys Inst
CCSDS AOS, TC, TC/TM
Sp
ace
Lin
k E
xten
sio
ns
C&DH
MCC
Future Missions?
Proximity Link:• Frequency band• Comm protocols• Multiple Access Scheme
Orbiter Deep Space Link:• Data rate (~power x gain)• Frequency (X, Ka)• Range variation (25x comm performance)
Current Relay Comms
Adapted from Wallace Tai’s IOAG presentation, June 2004
Proximity Link
Orbiter Deep Space Link
Current Relay Comms
Adapted from Wallace Tai’s IOAG presentation, June 2004
Data Link
Ph
ysicalD
ata Link
Ph
ysicalData Link
Physical
Data Link
Physical
Application
Application
Application
Networked Communications
• Multi-Hop– “Route around” obstructions– Heterogeneous links tuned to the environment
• Global Addressing– Applications don’t have to worry about where the
destinations are or how to get there
• Automated data forwarding– Fewer commanded data movements
• Efficient multiplexing of many applications
Data Link
Physical
Data Link
Physical
Data Link
Physical
Data Link
Physical
Application Application
Network NetworkNetwork
Forwarding IP Packets
10.4.0.110.3.0.0/16
10.4.0.110.2.0.0/16
Next HopDestination
10.4.0.110.3.0.0/16
10.4.0.110.2.0.0/16
Next HopDestination
10.4.1.1
10.4.1.3
10.1.0.0/16 10.2.0.0/16
10.3.0.0/16
10.4.0.0/1610.1.0.510.1.0.2
10.4.1.9
Destination Next Hop
10.1.0.0/16 10.1.0.2
10.2.0.0/16 10.4.1.3
10.3.0.0/16 10.4.1.1
Routing Protocols
10.4.0.110.3.0.0/16
10.4.0.110.2.0.0/16
Next HopDestination
10.4.0.110.3.0.0/16
10.4.0.110.2.0.0/16
Next HopDestination
10.1.0.0/16 10.2.0.0/16
10.3.0.0/16
10.4.0.0/16
I can reach 10.3.0.0/16
I can reach 10.1.0.0/16
I can reach 10.2.0.0/16
I can reach 10.2.0.0/16
I can reach 10.1.0.0/16,10.3.0.0/16
I can reach 10.3.0.0/16
I can reach 10.1.0.0/1610.2.0.0/16
Mixed Architectures
• Applications should still have access to data-link-specific services, they just aren’t end-to-end services
Data Link
Physical
Data Link
Physical
Data Link
Physical
Data Link
Physical
Application Application
Network Network Network
Application
Which Network Layer?
• Choices include– IP– ATM– IPX– AppleTalk– …
• Advantages of IP– NOT connection-oriented (don’t need end-to-end signaling to set
up path)– Wide availability of implementations / hardware
• Including small implementations suitable for flight software
– Interoperability with ground infrastructure• Simplifies testing / verification
Other Topics in Green Book
• Quality of Service• Security• Emergency Commanding• Overlay Communications
Terrestrial Data Transport
• What support is needed in the ground infrastructure to support IP-based missions?
• Spacecraft built by AgencyA that uses IP networking using AgencyB’s ground station– Several options, depending on ground station capabilities and
inter-agency connectivity characteristics• Space Link Extensions return-all-frames and return-channel-frames
services being prototyped now by NASA, ESA, JAXA
• Direct routed IP from the ground station– What changes would this require at ground stations?– What are the constraints on inter-agency connections (security, QoS)?
• Tunnel IP datagrams from ground station to mission operations– What changes would this require at ground stations?– What are the constraints on inter-agency connections (security, QoS)?
G/S AOSSLEAOSAOSCCSDS Space Packets
Interoperability Via SLE
CCSDS VC
SP Data
AOS
S/C MCC
SP Data
CCSDS VCAOS
SLE PayloadSLEIPSLE PayloadSLEIP SLE PayloadIP SLE
• Space link terminates at MCC• SLE characteristics (latency, jitter) are considered part of the space
link characteristics• IP datagrams, CCSDS Space Packets, … SLE doesn’t care
SP Data SP Data
G/S AOSSLEAOSAOSIP Packets
Interoperability Via SLE
CCSDS VC
IP Data
AOS
S/C MCCIP
Network
IP Data
CCSDS VCAOS
SLE PayloadSLEIPSLE PayloadSLEIP SLE PayloadIP SLE
• Space link terminates at MCC• SLE characteristics (latency, jitter) are considered part of the space
link characteristics• Can mix IP and Space Packets
IP Packets
IP Data IP Data
SP Data SP Data
G/S AOSSLEAOSAOSIP Packets
CCSDS Space Packets
Interoperability Via SLE
CCSDS VC
IP Data
AOS
S/C MCCIP
Network
IP Data
CCSDS VCAOS
SLE PayloadSLEIPSLE PayloadSLEIP SLE PayloadIP SLE
• Space link terminates at MCC• SLE characteristics (latency, jitter) are considered part of the space
link characteristics• Can mix IP and Space Packets
IP Packets
IP Data IP Data
G/S IPGREIPAOSIP Packets
IP Tunnel
CCSDS Channel
IP Data
AOS
S/C MCCIP
Network
IP Data
CCSDS ChannelAOS
• Space link terminates at Ground Station• Forces traffic through Mission Control Center• Different latency / jitter characteristics than SLE tunnel
IP Packets
IP Data IP Data IP Data IP DataGRE GREIP IP
AOS IP Packets
Downlink Return Via IP
CCSDS VC
IP Data
AOS
S/C G/S IPNetwork
IP Data
CCSDS VCAOS
IP Packets
• Space link terminates at the ground station• IP traffic delivery over the inter-agency cloud• Implications for security / uplink stream formation
IP Data IP Data
MCC
IP Packets
AOSSLEAOS
AOS IP Packets
CCSDS Space Packets
Mixed Approach
CCSDS VC
IP Data
AOS
S/C G/S MCC IPNetwork
IP Data
CCSDS VCAOS
SLE PayloadSLEIPSLE PayloadSLEIP
CCSDS Space Packets
IP Packets
• The approaches above can be mixed.
SLE PayloadIP SLE
IP Packets
Conclusions
• A network layer unifies possibly heterogeneous data links
• Automated data forwarding simplifies operations over what we do now or might do using current protocols
• An IP-based system leverages commercial technologies and can leverage the terrestrial infrastructure
• An IP-based infrastructure can handle the range of data types we currently envision and has shown flexibility in the past
• The technical issues with an IP infrastructure in space are addressable
• It’s possible to mix-and-match new routing components alongside traditional operations in the same spacecraft and terrestrial systems
Status
• Green book (architecture) done and about to be submitted to CESG for review (final editing completed last week)
• Starting first Recommendation dealing with ‘simple’ IP-based spacecraft operations– Focus on terrestrial interoperability
Questions?