# Emerging Trends in Hybrid Wireless Communication and Data Management for the Industry 4.0
## 4 5G for Industrial Wireless Networks: Recent Architectural Trends  
To support the necessary improvement of flexibility and versatility of industrial production and logistics, novel communication and data management solutions will be needed for the Industry 4.0. Supporting the use cases identified in Section 2 and addressing the challenges described in Section 3 will require a significant evolution of the current communication technologies and architectures available. In this section, we review the existing industrial wireless networks architectures. Traditional wired fieldbuses and Ethernet-based technologies can provide high communications reliability, but they are not able to fully meet the identified requirements in terms of flexibility, quick reconfigurability, and supporting mobile machines and robots, among others, and challenges of the Industry 4.0. WirelessHART, ISA100.11a and IEEE802.15.4e are some of the wireless technologies developed to support industrial automation and control applications. They consider a central network management entity that is in charge of the configuration and management at the data link and network levels of the communications between the different devices (gateways, routers, and end-devices). The main objective of a centralized network management is to achieve high communications reliability levels. However, the excessive overhead and reconfiguration time that results from collecting state information by the central manager limits their reconfiguration and scalability [28; 29]. To overcome this drawback, [PERSON], [PERSON] et al. [30; 31] proposed to divide a large network into multiple subnetworks, and considered a hierarchical management architecture. Each subnetwork is managed by a local manager and a global entity is in charge of the management and coordination of the entire network. Proposals in [31; 32] rely on hierarchical architectures and also propose the integration of heterogeneous technologies to efficiently guarantee the different communication requirements of industrial applications. One representative example is the KoI project [33] that proposes in [34] a two-tier management approach for radio resource coordination to support mission-critical wireless communications in the factory of the future. They consider the deployment of multiple small cells to guarantee the capacity and scalability requirements of the industrial environment. Each of these small cells can implement a different wireless technology and has a Local Radio Coordinator (LRC) that is in charge of the fine-grained management of radio resources for devices in its cell. A single Global Radio Coordinator (GRC) carries out the radio resource management on a broader operational area and coordinates the use of radio resources by the different cells to avoid inter-system and inter-cell interference among them. 5G networks are also being designed to support industrial wireless networks and the stringent communication requirements identified [35]. Considering the requirement of the use of private networks supporting non-public operation (as highlighted in Section 2), the use of Private 5G networks is proposed [36]. Private 5G networks will allow the implementation of local networks with dedicated radio equipment using shared and unlicensed spectrum, as well as locally dedicated licensed spectrum [18]. Two different types are defined: the so-called type-a network is a 3 GPP network that is not for public use and for which service continuity and roaming with a PLMN (public land mobile network) is possible, and the type-b network that is an isolated 3 GPP network that does not interact with a PLMN. The design of these Private 5G networks to support industrial wireless applications consider the implementation of several small cells to cover the whole industrial environment integrated in the network architecture [36] as shown in Figure 3, that depicts an example of a Private 5G network of type-b.