Impact of network conditions on delay-stable communications in closed industrial control networks

Abstract

To properly operate closed industrial control networks, it is required that communication with nearly constant delay bounds be supported. In [9] the authors introduced FlexTDMA in order to provide this support, and with minimal delay-jitter in an asynchronous network, under unicast communication. In this paper we consider how periodic on-off traffic and frame loss are managed in the presence of network component clock drifts and bandwidth loads, and introduce the FlexTDMA+ protocol. This protocol includes three improvements over FlexTDMA: baseline preemption, partial baselining and baseline deadline density control. In this paper we consider the relative value of each of these improvements, individually and in combination, has in handling these network conditions.