Data flow delay equalization for feedback control applications using 5G wireless dual connectivity

The emerging 5G networks are intended to enable new feedback control applications, run over multiple wireless interfaces. 5G wireless technologies then need to match the state-of-the- art wired network performance, experienced by present commercial feedback control systems. Fibre-optic circuit switched communication is characterized by constant and very low loop delays, uniform and very high sampling rates, very low error rates and an almost unlimited capacity. The non-trivial challenge is then to meet these characteristics with a packet switched wireless 5G network that may be associated with varying latency, time varying sampling rates, significant error rates and a varying air-interface capacity. The paper contributes with a summary and discussion of basic requirements that need to be in place for successful commercial deployment of feedback controllers using such 5G wireless networks. One key requirement is a need to mitigate the problem of delay skew between different transmission paths. A novel delay skew data flow control algorithm is therefore proposed for 5G dual connectivity. The stability of the controller is analyzed and conditions for global L₂-stability are stated. Test bed results are also reported in the paper, indicating that the delay skew controller can meet the requirements on the delay characteristics of 5G networks.