# An Experimental Framework for 5G Wireless System Integration into Industry 4.0 Applications
## 3 Experimental Framework for 5G Integration
### 5G Hardware and Software Prototyping Tools  
In order to execute our work throughout the different phases of the experimental operational flow, we developed a number of customized hardware and software prototyping tool devices:  
* Network traffic sniffer (NTS): intended to log all data passing through an ethernet interface and extract relevant network traffic statistics. * 5G Emulator (5 GE): aimed at introducing controlled delays into an ethernet link to imitate the communication performance of a wireless technology, e.g., 5G. * Wireless multi-access gateway (WMAGW): designed as the main integration element to enable the wireless transport, e.g., over 5G, of data traffic from a given ethernet-based interface. Although there currently exist commercial devices such as network traffic analyzers [14; 15; 16], network emulators [17; 18; 19] and 5G industrial devices [20; 21; 22], with somehow similar purposes and characteristics to the ones custom-developed by us, this was not the case at the time when our 5G integration experimental activities were initiated 4 years back. As it will be explained later for each of the individual prototypes, our custom designs offer us some benefits and flexibility that would not be possible to obtain by using commercial devices. Our reference designs consider ethernet interfaces for integration to the industrial machinery, as most of the industrial applications that will make use of 5G are currently operating over ethernet cables [23; 24]. However, it should be noted, that the design could be slightly adjusted to be integrated with other interfaces such as USB or fieldbuses. As illustrated in Figure 3, the NTS and the 5 GE have a very similar functional structure. Both devices shared an identical hardware (HW) configuration with two bridged ethernet ports that operate by forwarding the data input at one end to the other end. Their software (SW) implementation is, however, different. The NTS (Figure 3a) works as a \"man-in-the-middle attack\" [25] by executing a SW that logs relevant information from all the L2 and above data traffic packets passing through the bridge interface. Only headers are recorded. No packet inspection is done in order to preserve the confidentiality of the potential business-critical data contained in the payload of the control data messages flowing across the logged ethernet interface. The main use of the NTS box within the operational flow is done in STEP 2, when the data traffic analysis of the selected industrial application is performed. Compared with existing commercial network traffic analyzers, our NTS has similar form factor and functionality to the one developed by ProfiTAP [14]. Other network traffic analyzer solutions such as the ones from CISCO [15] or Solarwinds [16] are much more enterprise-oriented and offer extensive analysis suites, which makes perfect sense for live enterprise network monitoring but would be an overkill for our traffic characterization purpose. The main advantage of building our own analyzer is that the developed SW can be targeted to extract only relevant parameters of our interest such as number of flows, protocols, packets sizes, or packet inter-arrival times, without logging any payload with factory-critical information. This custom and controlled implementation plays in our favor as some of factories would not allow to connect commercial tools that logs and analyzes all their traffic uncontrollably. The 5 GE (Figure 3b) implements a different SW that introduces specific delays to the bridged communication link. The packets received by the 5 GE are restrained for a pre-configured delay which is obtained from the uniform sampling of a specific delay distribution pre-loaded from a configuration file. The 5 GE can be configured to emulate the delay performance of different wireless technologies by simply loading specific files containing distributions of empirical delay samples for a given technology, e.g., 5G. Suchfiles are generated by storing empirical samples from real-world lab traces such as the private 5G Rel.