Quasi Isochronous Wireless Communication Protocol for Co-Operative Heavy-Duty Vehicle Clusters

ISO TC 23/SC 19/WG 5 is working toward the creation of an open and unified standard that groups such needs, dividing them in two categories: very long range communication (bound to outside the cluster) and short/long range communication (inside the cluster, so assuming maximum communications range of 100 m). For the latter type of communication, IEEE 802.11 (Wi-Fi) is under investigation to be chosen as a physical layer, even if the technology does not provide necessary prioritization of traffic, for data that require a certain level of timeliness and reliability of receipt (real time data) over other less prioritized data (best effort data). Particularly for agricultural machine clusters, Wi-Fi variant "ad-hoc" architecture seems quite useful as needs no pre-existent network infrastructure such as access point. The same architecture could be applied to road building machine clusters, while in construction sites can be also designed an infrastructure serving the cluster operating in the area. The paper will focus on short/long range communication, utilizing 802.11g with "ad-hoc" infrastructure, describing the research done to grant prioritization of data streams and evaluating with tests (made at IMAMOTER Laboratory) the results achieved; experimental results demonstrate that it is possible to send several 10 ms-cadenced streams in a busy transmission channel, without packet losses and granting good statistical figures, so providing promising real time levels, to satisfy the cluster communication requirements both for real time and for bandwidth and communication reliability. This new protocol under test would allow a real time M2M synchronization, even considering indirect communication through machines (hopping), and a reliable channel to exchange working data in a logical parallel channel, thanks to a large bandwidth available and to the messages prioritization, which is the major novelty of the solution proposed.