A New SpaceWire Protocol for Reconfigurable Distributed On-Board Computers

Abstract

There are several standardized protocols based on SpaceWire which provide data exchange between several nodes. SpaceWire is also suitable for interprocess communication (IPC), by the help of higher level protocols. However, currently there is no standardized protocol which is targeting IPC on SpaceWire networks. This paper proposes a protocol, which uses the capabilities of SpaceWire to build up networks for distributed computing on a spacecraft. The core of this protocol is the IPC mechanism for communication between the nodes and methods to support a reconfiguration of the network. A key feature of this protocol is an interface for a reconfiguration mechanism, which can be implemented on application level. This enables the utilization of unreliable commercial off the shelf (COTS) nodes, allowing system recovery from erroneous state. Additionally, the reconfiguration can be used to adapt the distributed computer to different mission phases. The protocol has the potential to build the foundation of a distributed on-board computer consisting of COTS components. Such distributed computer could be capable of fulfilling high performance demands as well as high reliability needs. Though, the protocol itself is not restricted to be used solely in fully-featured reconfigurable distributed systems. The IPC methods can be applied stand-alone as well, to establish a lightweight communication between nodes on a SpaceWire network by excluding the reconfiguration parts of the protocol.