# Emerging Trends in Hybrid Wireless Communication and Data Management for the Industry 4.0
## 5 Hierarchical and Multi-Tier Communication and Data Management for the Industry 4.0
### Hybrid Communication Management  
Communication systems must be able to support the high dynamism of the industrial environment that will result from the coexistence of different industrial applications, different types of sensors, the mobility of nodes (robots, machinery, vehicles and workers), and changes in the production demands. Industry 4.0 thus demands flexible and dynamic communication networks able to adapt their configuration to changes in the environment to seamlessly meet the communication requirements of industrial applications. To this end, communication management decisions must be based on current operating conditions and on the continuous monitoring of experienced performance. Our hierarchical communication and data management architecture allows the implementation of hybrid communication management schemes that integrate local and decentralized management decisions while maintaining a close coordination through a central management entity (the Orchestrator) with global knowledge of the performance experienced in the whole industrial communication network. The hybrid communication management introduces flexibility in the management of wireless connections and increases the capability of the network to detect and react to local changes in the industrial environment while efficiently guaranteeing the communication requirements of industrial applications and services supported by the whole network. In hybrid management schemes, management entities must interact to coordinate their decisions and ensure the correct operation of the whole network. Figure 6 represents the interactions between the management entities of the hierarchical architecture: the Orchestrator, LMs, and end-devices (as presented in Section 5, end-devices might also participate in the communication management). Boxes within each management entity represent different functions executed at each entity:  
* Local measurements: This function measures physical parameters on the communication link, for example, received signal level (received signal strength indication or RSSI), signal to noise ratio (SNR), etc. In addition, this function also measures and evaluates the performance experienced in the communication, as for example, throughput, delay, PER, etc. This function is performed by each entity on its communication links. * Performance gathering: This function collects information about the performance experienced at the different cells. This function is performed at the LMs, which collect performance information gathered by end-devices within its cell and at the Orchestrator, which receives performance information gathered by the LMs. * Reasoning: The reasoning function processes the data obtained by the local measurements and the performance gathering functions to synthesize higher-level performance information. The reasoning performed at each entity will depend on the particular application supported (and the communication requirements of the application), and on the particular management algorithm implemented. For example, if a cell supports time-critical control applications, the maximum value of latency experienced by the 99 th percentile of packets transmitted might be of interest, while the average throughput achieved in the communication could be required to analyze the performance of a 3D visualization application. * Reporting: This function sends periodic performance reports to the management entity in the higher hierarchical level. Particularly, end-devices send periodic reports to the LMs, and LMs report performance information to the Orchestrator. * Global/Local/Communication management decision: This function executes the decision rule or decision policy.