# 5G NPN Performance Evaluation for I4.0 Environments
## 4 I.4.0 and 5G Framework Evaluation Measurements  
This section presents the 5G NPN performance tests, deployed for a simulated I4.0 scenario. The purpose of these experimental sets was to replicate an industrial communication use-case considering multiple devices and different requirements. The deployed 5G NPN testbed was configured to operate under different configurations with different strict network requirements for gateways and devices. This set of measurements refers to the measurements of uplink, downlink, and RTT of a 5G NPN operating in an I4.0 environment. It is based on an SA 5G network implemented through an AMARISOFT callback, according to 3 GPP Release 16. The AMARISOFT callback provides a stable 5G mobile network system for testing and experimentation. Both the 5G core and 5G RAN (gNodeB) functions were software-defined and were run on an x86 Linux-based host. The 5G RAN operated PCIe SDR boards as an RF front-end. The system used for the measurements supports TDD transmission mode, with the ability to allocate different slots for the uplink and downlink channels. The bandwidth was 40 MHz, and the supported modulation schemes ranged  
Figure 5: Downlink rates for different TDD values. up to 256 QAM for the downlink transmission channel and 64 QAM for uplink. The 5G terminals were commercial 5G mobile phones. The flexibility in the Time-Division Duplex (TDD) mode of operation makes 5G ideal for communications on the factory floor, as the allocation of different time slots in the uplink and downlink may fulfill the requirements for the various equipment present. TDD in 5G is commonly used in scenarios where the uplink and downlink data rates are asymmetrical, and its most common deployment type is in dense topologies with low-power nodes [34]. This network deployment better supports applications that include positioning, mobility, and multicast communications. Regarding different slicing types, eMBB is characterized by large payloads and a device activation pattern that remains stable over an extended time interval. This allows the network to schedule wireless resources to the eMBB devices, such that no two eMBB devices access the same resource simultaneously. The objective of the eMBB service is to maximize the data rate. In contrast, an mMTC device is active intermittently, and uses a fixed (typically low) transmission rate in the uplink. A huge number of mMTC devices may be connected to a given Base Station (BS) but, at a given time, only an unknown (random) subset of them becomes active and attempts to send their data. Finally, URLLC transmissions are also intermittent, but the set of potential URLLC transmitters is much smaller than for mMTC. Supporting intermittent URLLC transmissions requires a combination of scheduling in order to ensure a certain amount of predictability in the available resources, thus supporting high reliability as well as random access, in order to avoid too many resources being idle due to the intermittent nature of the traffic. Table 1 shows the measured downlink and uplink bit rates and RTT (Round-Trip Time) under various RSRP (Reference Signal Received Power) levels and three TDD schemes. TDD_1 allocates seven time slots for DL, two time slots for UL, and one flexible time slot; TDD_2 allocates six time slots for DL, three time slots for UL, and one flexible time slot; and TDD_3 allocates an equal number of time slots for DL and UL. The symbol period in TDD_1 and TDD_2 is 5 ms, while that for TDD_3 is 2.5 ms. The different RSRP values represent different sets of devices present on the factory floor, which were placed at different positions. This representation can help us to evaluate the performance under different network conditions, as well as the maximum data link speed that could be achieved via 5G. In our case, eMBB slicing is represented by the TDD allocation for large bit rate values (namely, TDD_1 7 dl 2 ul with low RSRP), mMTC slicing is represented by the RSRP values (as mentioned previously), and uRLLC is depicted by the lowest delay value of RTT.