Scheduling mechanisms for spacewire networks

The paper describes two mechanisms which solve the problem of time multiplexing for SpaceWire networks. They are a transport-level scheduling mechanism, which is used in the STP-ISS protocol, and SpaceWire-DSUAI, that is a protocol prototype. The current paper presents an overview of these mechanisms and compares them. In addition, we provide a short analysis of time-division multiplexing in the communication protocols

Worst-case end-to-end delays evaluation for SpaceWire networks

SpaceWire is a standard for on-board satellite networks chosen by the ESA as the basis for multiplexing payload and control traffic on future data-handling architectures. However, network designers need tools to ensure that the network is able to deliver critical messages on time. Current research fails to address this needs for SpaceWire networks. On one hand, many papers only seek to determine probabilistic results for end-to-end delays on Wormhole networks like SpaceWire. This does not provide sufficient guarantee for critical traffic. On the other hand, a few papers give methods to determine maximum latencies on wormhole networks that, unlike SpaceWire, have dedicated real-time mechanisms built-in. Thus, in this paper, we propose an appropriate method to compute an upper-bound on the worst-case end-to-end delay of a packet in a SpaceWire network

Modeling SpaceWire networks with network calculus

The SpaceWire network standard is promoted by the ESA and is scheduled to be used as the sole on-board network for future satellites. This network uses a wormhole routing mechanism that can lead to packet blocking in routers and consequently to variable end-to-end delays. As the network will be shared by real-time and non real-time traffic, network designers require a tool to check that temporal constraints are verified for all the critical messages. Network Calculus can be used for evaluating worst-case end-to-end delays. However, we first have to model SpaceWire components through the definition of service curves. In this paper, we propose a new Network Calculus element that we call the Wormhole Section. This element allows us to better model a wormhole network than the usual multiplexer and demultiplexer elements used in the context of usual Store-and-Forward networks. Then, we show how to combine Wormhole Section elements to compute the end-to-end service curve offered to a flow and illustrate its use on a industrial case study

SHINe: Simulator for satellite on-board high-speed networks featuring SpaceFibre and SpaceWire protocols

The continuous innovation of satellite payloads is leading to an increasing demand of data-rate for on-board satellite networks. In particular, modern optical detectors generate and need to transfer data at more than 1 Gbps, a speed that cannot be satisfied with standardized technologies such as SpaceWire. To fill this gap, the European Space Agency (ESA) is supporting the development of a new high-speed link standard, SpaceFibre. SpaceFibre provides a data-rate higher than 6.25 Gbps, together with the possibility to use multiple Virtual Channels running over the same physical link, each one configurable with flexible Quality of Service parameters. These features make a SpaceFibre network very appealing but also complex to set up in order to achieve the desired end-to-end requirements. To help this process, a Simulator for HIgh-speed Network (SHINe) based on the open-source toolkit OMNeT++ has been developed and is presented in this paper. It supports the simulation of SpaceFibre and SpaceWire protocols in order to help both the final steps of the standardization process and the system engineers in the setup and test of new networks. SHINe allows to precisely simulate common network metrics, such as latency and bandwidth usage, and it can be connected to real hardware in a Hardware-in-the-Loop configuration

Second revision of the STP-ISS transport protocol for on-board spacewire networks

The paper provides an overview of the second revision of the Transport protocol STP-ISS, which is developed for SpaceWire on-board networks. Current R&D activity is performed by the specialists of SUAI and JSC “ISS”. The paper shortly compares two revisions of the specification and describes the main mechanisms and quality of service types of the second revision of the protocol. STP-ISS is planned to be used for the next generation spacecrafts

QoS support in embedded networks and NoC

Quality of service (QoS) requirements such as priorities, packet delivery and packet delivery time are important and critical for embedded networks and networkson-chip (NoC) [1]. We consider mechanisms for QoS support in the SpaceFibre, SpaceWire and GigaSpaceWire protocols, possibility of using them in embedded networks and NoC. In the article we analyze approaches for QoS provision, their feasibility and value of QoS in SpaceWire/GigaSpaceWire and in SpaceFibre networks. Networks with different topologies and traffic pattern are used to study and to evaluate the performance. Various traffic types such as the data packets, streaming data, commands will be transmitted in networks. Data delivery characteristics for SpaceFibre and SpaceWire/GigaSpaceWire networks are analyzed and compared. Also we compare characteristics that are achievable in NoC, which are based on QoS mechanisms of SpaceFibre, SpaceWire and GigaSpaceWire. Hardware costs are one of the main constraints for embedded networks and NoC. Therefore we compare hardware costs of basic SpaceFibre, SpaceWire and GigaSpaceWire routers