# Broadband Power Line Communication for Integration of Energy Sensors within a Smart City Ecosystem
## 7 Simulation of Real Scenario and Comparison with Real Measurement  
The series of measurements were performed under real conditions on the medium-voltage (MV) powerline. The measurements were performed between all substation nodes in the trace. The aim was to measure the point-to-point communication without repeaters and to find the effect of distance on transmission parameters. The target parameter was the throughput at the application layer.  
The MV cable routes are composed of several types of cables of different lengths (see Figure 10). In the case of the S2-S3 route, the route contains three junctions with four cables. The topological conditions between the substations are defined according to Figure 6. The maximum number of junctions on one trace was five, where two were a part of the substation (immediate nearness of the substation switchboard). The longest measured trace of this topology was approximately 515 m. At the time of measurement, it was not possible to determine more precisely conditions such as the temperature and ambient humidity of individual junctions or cables. According to our own observations from the long-term measurements over a number of weeks, we found a change in the transmission rate, loss of transmission and other parameters depending on the day and time of communication (humidity after rain could be the reason).  
EXFO FTB-Pro instruments which were connected to BPL modems via the Ethernet interface were always used for measurements. The measurement methodologies RFC2544 were employed. The achieved values of throughput (transmission speed on a UDP communication layer) are always the average values for the entire measurement period.  
The RFC2544 methodology measures the parameters on the third layer of the ISO/OSI model--the network layer. The methodology is based on the UDP protocol, i.e., an unreliable protocol. The testing methodology allows the creation of multiple data streams with different specifications within the Ethernet interface. In the case of these results, the configuration was always optimized for the optimal value of maximum throughput, to achieve the minimum error rate. Furthermore, it is necessary to define the size of the transmitted frame for each data stream. In total, the measurement was performed when transmitting one stream with a frame size of 256 bytes and when transmitting three streams with a size of 256, 512 and 1024 bytes. Two series of measurements using the RFC2544 methodology were performed to test the throughput of the simulated UDP traffic in one direction and to test the response of communication by looping nodes.  
Figure 11 shows the throughputs of UDP-based communication in one direction in sub-sections (point-to-point communication). Figure 12 shows the impact of distance on throughput. The order is not geographically correct, as the topology in Figure 10 shows, but the sections are sorted according to their distances from the shortest to the longest. The important point is that traces do not consist of single cables, but of several different cables with separate junctions. It is possible to see the impact of real variable conditions.  
Figure 10: Diagram of the measured and simulated topology with full distance between substations.  
Deviation of measured values of throughput from the theoretical trend line interpolation can be observed. The theoretical trend line is applicable for expected results of the BPLC technology on MV lines. The detected differences may be caused mainly by the variability of the environment and the specific parameters of all elements in the communication path, such as the specified ambient humidity and the age of cables and junctions. Based on this measurements and knowledge of physical cable parameters (cable age, junction, cable type), the precondition for BPLC installation in another area is known. The achieved speeds are considered sufficient within the deployed smart grid solution in terms of the throughput and the reliability of communication in the infrastructure.