CCSDS SOIS Wireless BoF

CCSDS Fall Meeting. TOULOUSE, 18 November 2004

CCSDS SOIS Wireless BoF


Agenda1 Justification to consider OW solutions for on-board communications

2 State of the Art Review – Feedback of Optical Wireless Workshop September 2004

3 Planned Activities

4 Discussion & Conclusions (All)


• Reduction in the nº of cables and connectors

• Flexibility: Ease the test and integration phases Late integration in S/C does not affect existing topology Mechanical obstructions prohibit wired solution

• Potential cost & time savings.

OPTICAL (vs. RF) •Fulfilment with S/C EMI immunity requirements •Large unregulated bandwidth • High miniaturization capability

…so then not only intra-S/C communications are suitable, also benefits may be provided in:-Mechanisms & Robotics mobile harness suppression-Life Science Monitoring if Human Physiological data-Test Facilities Non intrusive operations

1.- Reasons to consider On-board wireless communication solutions. easons to consider free-space solutions:


Added value expected with the introduction of OW comms:

-Availability if new functions-Greater flexibility in S/C design and construction-New design approach of Space Instruments-New possibilities for Space Missions


2.-State of the Art Review

Concluded activities under different ESA Programmes:Concluded activities under different ESA Programmes:

1.-Optical Wireless Links for Intra-Satellite Communications


Low Speed Diagram(Diffuse network at 19.2Kbps)


Infrared Block


High Speed Diagram (Analogical LOS link of BW~ 500MHz)


Laser Module


Concepts demonstrated:


2.-‘Validation of a Wireless optical layer for on board data communications in an operational context’Goal: To review and identify an optical wireless communication system fulfilling the basic requirements of the internal data communication function of an on board control and data system and its suitability for space applications.

Specification of requirements:

-Type of communication: •Low to medium speed data (<10 Mbps) and local sensor bus —————————————————— capability. Large number of users.

• High speed data (~hundreds of Mbps)

- Commercial-Off-The-Shelf Technology.

TWO CONTRACTS,TWO DIFFERENT APPROACHES:

-EADS-Astrium with UPM Take the option of using ‘COTS’ IrDa standardcompliant and developing and ad hoc protocol.

-INTA with Alcatel Take the option of using COTS parts to implement a full wireless physical layer below a medium rate speed 1553 bus and a low rate ‘sensor bus type’ with adhoc (SPI based) protocol.


1.-Proposed Astrium demonstrator environment: ROCSAT (Leostar satellite family)

Presentation of ROCSAT-2:

1st application of Astrium’s Leostar bus


Case study : ROCSAT-2

OBMU

IPU

SSR

TRSP

EPC

SQPSK

TWT

DRUBattery

MTQ

Wheels

MAG

GPS


Concepts demonstrated:

HW ARCHITECTURE

The demonstrator architecture includes the following units:• The OBC that controls the entire network. It sends the commands to

equipments and receives data from them. • The AOCS and µRTUs equipments that are part of the critical platform

bus. These equipments generate a low data rate (few kilobits per second).

• A medium data rate payload equipment that generate data for up to 1 Mbps.

• A high rate payload instrument generating up to 100 Mbps.

Bus Architecture


o - The low rate data bus architecture is a multi-points link at 115kbps using 10 receivers; 10 repeaters are also used to insure the link budget inside the spacecraft.o - The medium rate data bus architecture is a point-to-point link at physical layer level (1Mbps)o -The high rate data bus architecture is a point-to-point link with communication protocol (100Mbps) SW ARCHITECTURE

t

OBCStar

TrackerSun

sensorsIMU

Reactionwheel

RCS OBCµRTU1

dt1

dt2

dt3

dta

100 ms

Synchronous transfersAsynchronous

transfers

…

< 20 ms > 80 ms

Inter Frame Space

OBC OBC …OBC OBC OBC…


The low-rate data bus protocol decomposes the data exchanges in two parts: synchronous and asynchronous.

The synchronous communication protocol allows to roughly simulate the use of standard data buses as the MIL-STD 1553B or more recently the CAN in space systems. All the data exchanges are initiated by the main calculator (master) that emits a command to a single equipment (slave) at precise times.

The asynchronous communication allows to simulate the behavior of standard data buses used on ground as 802.3 (LAN) and 802.11 (Wireless LAN). All the data exchanges are initiated by the equipments. The main difference between the synchronous and asynchronous transmission lies in the collisions that can happen in the asynchronous mode.


2-INTA’s Demonstrator

RTU

Wired sensors

OW Low-speed Network (<128Kbps)

RTU

External pay-load

OW 1553 Medium speed Netwok (1Mbps)Video

camera

Dummy boxes

OW High speed Link (200 Mbps)

•


Demonstrator Architecture:

Re-definition of hierarchy to adapt to SCI-PT-ICD-07527:

2-INTA’s Demonstrator(ll)

OBC(1553-BC)

RTU0

RTU1 RTU2

RTU00

RTU01

RTU02

RTU10

RTU11

RTU12

RTU13

RTU3

RTU20

RTU21

RTU22

RTU23

RTU30

RTU31

RTU32

RTU33

Medium-Speed Network at 1Mbps (MIL-STD1553B Protocol)

Low-Speed Network at Kbps

(SPI)

OBC(1553-BC)

+•••

High Speed Video Link: digital, >200Mbps

Total 120 channels (analg.+digit)


Concepts demonstrated:1.-LINK CONFIGURATION

2.- MODULATIONS

-Baseband OOK for the transmission of the Manchester coded signal of the MIL-STD-1553 (1Mbps)

-Pass-band ASK for the communication between RTU and µRTUs

3.-MEDIUM ACCESS

-SDMA Bus MIL-STD-1553/Local bus(SPI)

-WDMA 1 RTO0

2 RTO1,RTO2,RTO3

-FDMA f1, f2 ,f3 RTO1,RTO2,RTO3

-Master/Slave BC RTUs (MIL-STD-1553)

RTU µRTUs

HSL:video transmission

MSN:MIL-STD-1553

LSN: Local sensor bus (SPI)


3.-A-I-T Optical Links for ESTEC LSS (on-going)

Feed-through

ESTEC LSS

Feed-through

ESTEC LSS


3.- Planned activities in the field of Optical Wireless comms:3.- Planned activities in the field of Optical Wireless comms:

4.-Optical /Wireless Intra-Satellite Communications (scheduled)

Taking into account the Work performed so far, the next activity is dedicated to implement an optical wireless intra-satellite communications subsystem or application in a realistic model of a satellite and prepare a flight demonstration of the selected application.

CCSDS SOIS Wireless BoF

Documents

Transcript of CCSDS SOIS Wireless BoF