Modelling of SpaceFibre networks
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Document typeMaster thesis
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This work presents the implementation of the SpaceFibre protocol for the network simulator MOST NS-3. On board data networks interconnect satellite's modules with mixed requirements on time of deliver delay and jitter. For example, the same link on a network can be shared to retrieve payload telemetry and to receive satellite attitude sensors telemetry. While payload telemetry can usually wait and support some level of delay, attitude sensors telemetry must arrive within an strict window of time. Several protocols try to solve this problematic. One of them is SpaceFibre, an evolution of SpaceWire that introduces Quality of Service at data link layer by using virtual channels (VC). Virtual channels compete to access the link based on their priority, bandwidth reservation and scheduling. Despite the capabilities of SpaceFibre, with complex onboard satellite networks a question arises: are the jitter and delay requirements fulfilled? To answer that question a network simulator is needed. MOST on NS-3 is a network simulator developed by Thales Alenia Space that implements SpaceWire and related protocols. The outcome of this work is an implementation of the SpaceFibre protocol for MOST NS-3. The model implements all the procedures that introduces a delay in the transmission of a packet including lane initialization, the time that a packet frame waits in a buffer due to the multiplexing of several virtual channels in the same link, words precedence or frame recovery mechanisms. Several tests are included to validate that the implementation meets the requirements of the SpaceFibre protocol.
The tool MOST (Modelling of SpaceWire Network) is an open source tool for satellite networks simulations developed by Thales Alenia Space based on the simulator NS3. The goal of this work is to extend the functionalities with the programming of a new module for the SpaceFiber standard.