Globally Stable Delay Alignment for Feedback Control Over Wireless Multipoint Connections

Abstract

The 5-G ultra reliable low latency communication standard is intended, for example, to enable new use cases based on networked feedback control. This article argues why additional delay control and alignment are needed, to meet the well-established feedback control requirements on low end-to-end loop delay and jitter. The main contribution of this article is a novel re-engineered delay aligning data flow controller, where a new static decoupling matrix is introduced. The intention is to obtain a multiple single loop control architecture that allows global robust $\mathcal {L}_2$ -stability to be proven. The algorithm is suitable to regulate $n+1$ end-to-end roundtrip delays of a 5-G multiconnectivity connection toward zero pair-wise delay differences. The new stability result is decisive for massive deployment, since weaker results would increase the need for supervision and raise operating costs significantly. A robot arm control loop application operating over three data paths illustrates the performance advantages associated with delay alignment and the proposed algorithm.