Communication Integrity in Networks for Critical Control Systems

Anis Youssef, Yves Crouzet, Agnan de Bonneval, Jean Arlat, Jean-Jacques Aubert, Pascal Brot

Abstract

The paper proposes a solution to the problem posed by the inclusion of complex interstage nodes into communication networks. Thus nodes are prone to exhibit failure modes that may lead to repetitive errors that breach the usual set of assumptions considered for medium-level protection mechanisms. The specific class of application targeted (e.g., servomechanisms controlling flight control surfaces) is characterized by: i) slow dynamics of the controlled processes does not impose a high integrity level for each transmitted message, but rather for a set of successive messages, ii) the reference values assigned during the mission (e.g., cruise phase) are expected to be maintained identical for several cycles, and thus should the protection fail for one message, then it will be the same for subsequent messages. To cope with this, the proposed integrity protection scheme features distinct error coding functions, thus providing complementary detection capabilities to consecutive messages.

Keywords: Safety-critical systems, digital communications, interstage nodes, integrity, error detecting codes.