Wireless Virtual Multiple Antenna Networks for Critical Process Control: Protocol Design and Experiments

Abstract

Wireless telemetry systems for remote monitoring and control of industrial processes are now becoming a relevant topic in the field of networked control. Wireless closed-loop control systems have stricter delay and link reliability requirements compared to conventional sensor networks for open-loop monitoring and call for the development of advanced network architectures. By following the guidelines introduced by recent standardization, this paper focuses on the most recent technological advances to enable wireless networked control for tight closed-loop applications with cycle times below 100 ms. The cooperative network paradigm is indicated as the key technology to enable cable replacing even in critical control applications. A cooperative communication system enables wireless devices placed at geographically separated locations to act as a virtual ensemble of antennas that creates a virtual multiple-antenna-distributed system. A proprietary link-layer protocol/based on the IEEE 802.15.4 physical layer has been developed and tested in an indoor environment characterized by non-line-of-sight (NLOS) propagation and dense obstacles. The measurements obtained from the testbed evaluate experimentally the benefits (and the limitations) of cable replacing in critical process control.

Distributed signal processing for dense 5G IoT platforms: Networking, synchronization, interference detection and radio sensing

“…3-(a), a sequence of cooperative transmissions is implemented to connect a source and a destination CA node, while the CNs act as intermediate decode and forward relays [17]. The cooperative link abstraction consists here of separate radios encoding/transmitting or decoding/receiving messages in coordination [18,19]. Experimental validations in controlled laboratory environments (e.g., see [20]) showed that such systems could achieve enhanced reliability compared to standard multi-hop solutions thus mimicking the performance of a wired system.…”

“…Experimental validations in controlled laboratory environments (e.g., see [20]) showed that such systems could achieve enhanced reliability compared to standard multi-hop solutions thus mimicking the performance of a wired system. Despite some recent attempts to develop cooperative relaying features tailored to wireless IoT networks [19,21], practical methods to integrate such schemes into an industrial standard are still missing [10]. In the proposed setup, validated in the next section by experiments, the communication among the CNs takes place over consecutive DPCH slots.…”

“…In more details, the CA source node tunnels the input datagrams through the cloud section: each CN here handles data forwarding by "duo-cast" mode (e.g., transmitting the same datagram/packet towards the two following nodes in the route path), until reaching the CA destination node. Thus, each packet always has two propagation opportunities; likewise, the destination node has always two packet receive opportunities, corresponding to a "cooperative diversity" order [19] equal to 2. In what follows, the performance indicator adopted for performance assessment is the latency (e.g., 95-th percentile), measured with respect to the first successful datagram reception.…”

A Wireless Cloud Network Platform for Industrial Process Automation: Critical Data Publishing and Distributed Sensing

“…Information theoretic (see, e.g., [19] and references therein) as well as experimental validations in confined environments [20] showed that those systems could achieve enhanced reliability compared to standard solutions as mimicking the performance of a wired system. Despite some recent attempts to develop cooperative relaying features tailored to IEEE 802.15.4 sensor networks [21] [22], practical methods to integrate such schemes into a fully fledged industrial standard are still missing.…”

“…2-(a)). A cooperative-multihop forwarding scheme [22] is engineered and adapted so as to leverage both spatial and temporal diversity [19] for point-topoint data transmission (Sect. III-B).…”