OCARI (acronym of Optimization of Communication for Ad hoc Reliable Industrial network) is a communication protocol for Industrial Wireless Sensor Network. It is developed by the following consortium during the OCARI project that is funded by the French National Research Agency (ANR):
- Électricité de France, project leader
- One-RF Technologies now Telit RF 
- A deterministic access method to the RF medium supporting time-constrained packets relay, called MaCARI.
- A proactive energy efficient routing strategy supporting nomadism, called EOLSR (Energy efficientOLSR).
- An activity scheduling mechanism that is based on a three-hop coloring algorithm helps to reduce interference and thus optimizes node's energy consumption, called SERENA.
OCARI was developed to satisfy the user needs in constraint environments that are founded in Power Plants and in Warships. Typical applications of OCARI are:
- Real time monitoring of dosimetry.
- Real time radiation protection monitoring using mobile radiameters.
- Machine and equipment surveillance for predictive maintenance.
- Mobile instrumentation for test and measurement during outage periods.
- Open-loop control.
OCARI has three types of nodes that are similar to the ones adopted by ZigBee:
- Cluster coordinator is the global coordinator of a wireless sensors cluster. Its role is to initialize the network and to manage it: network address assignment, network access control, sensors gateway.
- Cell coordinator: it manages intra-cell communications and contributes to the hierarchical tree packets relaying mechanism as well as to the ad hoc routing activity inside the cluster.
- End device: it is usually connected to the sensor/actuator transmitter. It has limited resource (energy and memory...) and cannot directly communicate between them. It can only communicate with its Cell coordinator which, if required, reroutes the packets to their target.
A Cell coordinator can manage up to 7 end devices. A Cluster coordinator can manage up to 50 Cell coordinators so that a cluster can gather up to 400 nodes (8*50).
- (English) Khaldoun Al Agha, Marc-Henri Bertin, Tuan Dang, Alexandre Guitton, Pascale Minet, Thierry Val and Jean-Baptiste Viollet, “Which wireless technology for industrial wireless sensor networks? The development of OCARI technology”, IEEE Transactions on Industrial Electronics, Vol. 56, No. 10, October 2009.
- (English) Internet Web site of the OCARI project