Determinism through Path Diversity: Why Packet Replication Makes Sense

Industrial low-power wireless mesh standards, such as IEEE802.15.4-TSCH, WirelessHART and ISA100.10a, offer wire-like end-to-end reliability and a decade of battery lifetime. These technologies have become de-facto standards, used in the most demanding applications such as industrial process monitoring. In this paper, we explore what it takes to go from industrial process monitoring to industrial process control. The difference is that, in the latter case, the network needs to provide low and predicable latency, and deterministic operation. We explore the overall usefulness of packet replication, in which a source node sends multiple copies of a packet on disjoint multihop paths. We show, through extensive simulation, that packet replication allows for a reduction of end-to-end latency by 40%. In addition, packet replication significantly improves the network reliability through path diversity. This work is directly in line with standardization activities at the IETF 6TiSCH and DetNet working groups, to which it is being contributed.