Possibilities of Broadband Power Line Communications for Smart Home and Smart Building Applications

sensors Article Possibilities of Broadband Power Line Communications for Smart Home and Smart Building Applications Petr Mlýnek *,† , Martin Rusz †, Lukáš Benešl †, Ján Sláˇcik †and Petr Musil †   Citation: Mlýnek, P.; Rusz, M.; Benešl, L.; Sláˇcik, J.; Musil, P. Possibilities of Broadband Power Line Communications for Smart Home and Smart Building Applications. Sensors 2021,21, 240. https://doi.org/ 10.3390/s21010240 Received: 1 December 2020 Accepted: 23 December 2020 Published: 1 January 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Department of Telecommunications, Brno University of Technology, Technicka 12, 61600 Brno, Czech Republic; [email protected].cz (M.R.); [email protected].cz (L.B.); [email protected].cz (J.S.); [email protected].cz (P.M.) *Correspondence: [email protected].cz † These authors contributed equally to this work. Abstract: Broadband Power Line communication is considered as one of possible communication technologies for the buildings communication infrastructure in the concept of Smart Building. The possible applications where BPL (Broadband over Power Lines) solution can be used for communication in the concept of Smart Building are Power Quality (PQ) measurement, Electric Vehicle or Micro Grids and Distribution Generation (DG). This article should help to determine clear performance possibilities of BPL for an implementation in Smart Building especially due to a large amount of overhead caused by cybersecurity and the protocol overhead. The possibilities of BPL were measured with five different BPL solutions. The results show a sufficient throughput on the application layer for Smart Building application, because, in the literature, various throughput limits are introduced. According to related work, there are missing measurements on the application layer for laboratory conditions as well as compared with real field measurements. In this article, we also exploit our novel idea of a broadband PLC (Power Line Communication) modem integrated into an electrical outlet. Keywords: broadband over power line; power line communication; laboratory measurement; field measurement; performance comparison 1. Introduction In recent years, with the development and availability of technology, the concepts of Smart Building, Smart Cities and Industry 4.0 have become more and more widespread. The Smart Building environment is characterized by the control and operation of home appliances, heating or air conditioning, as well as the signaling of unexpected events and the correct response of the system to this event. Everything aims to increase energy efficiency and reduce emissions [1–3]. One of the possible technologies suitable for this type of application is Power Line Communication (PLC). PLC uses existing power line wiring for the transmission of the information signal on the carrier frequency of low voltage (LV), medium voltage (MV) or high voltage (HV). PLC is the technology that can be compared to wireless solutions in terms of the cost of building a communication infrastructure, because power lines are already built and are available everywhere. Thus, the main advantage is the saving of funds for building a communication infrastructure. PLC technology can be divided into two basic variants [4]: •Narrowband PLC : This technology operates in the 3–500kHz frequency band, which includes the European CENELEC band 3–148.5kHz, the US FCC band 9–500kHz, the Chinese band 3–500kHz and the Japanese ARIB band 10–450kHz [ 5 , 6 ]. According to the data bit rate, this technology can be further divided into: – Low Data Rate (LDR): These are technologies with a single carrier and a data rate of several kbps. Typical examples of LDR NB-PLC are LonWorks standards, IEC 61334, X10, HomePlug C&C and SITRED. Sensors 2021,21, 240. https://doi.org/10.3390/s21010240 https://www.mdpi.com/journal/sensors Sensors 2021,21, 240 2 of 17 – High Data Rate (HDR): These are multi-carrier technologies with data rates from tens of kbps to 500kbps. Typical examples are technologies based on ITU-T standards by G.hn, IEEE P1901.2, PRIME and G3-PLC. •Broadband PLC : Broadband technology operates in the 1.8–500MHz frequency band and features data rates at the physical layer from a few Mbps to Gbps. It is sometimes also referred to as Broadband over Power Lines (BPL). Broadband technology standards are covered by several organizations such as Universal Powerline Association (UPA), Open PLC European Research Alliance (OPERA), Consumer Electronics Power line Communication Alliance (CEPCA), Institute of Electrical and Electronics Engineers (IEEE), International Telecommunication Union (ITUT-T) and HomePlug Powerline Alliance. The biggest difference between the standards of individual organizations is mainly in the methods of access to the shared medium, methods of encryption and robustness of transmission. The used frequency bands, modulations and the injection of the useful signal into the electrical network are almost identical across the standards. To ensure support for all protocols used in Smart Building applications, as well as the possibility of sufficient communication security, the broadband PLC technology is being considered for the Smart Building concept. It provides a greater throughput at the expense of a shorter communication range. Throughput, efficiency, packet loss, interference immunity and communication range are the key parameters that need to be determined in the deployment of this technology. There is no doubt that deployment of BPL networks is an alternative or complement to technologies such as Long Term Evolution (LTE), 5G, Digital Subscriber Line (DSL) or fiber optic. There are huge deployments based on BPL communication for energy consumption and energy bills savings, battery management of loads and flexible energy tariffs. For example, the largest deployment was in Germany in Modellstadt Mannheim with 3000 homes [7] . Another deployment of BPL with 12,000 electricity and water meters was Kahramaaa’s in Qatar [ 8 ]. E.ON (name of electric utility company) is in the process of a 200,000 home roll-out based on BPL [ 9 ]. The main applications based on BPL in Smart Building are: Power Quality : The distributed power system has been increased with solar and wind power local facilities, which make the grid more heterogeneous and difficult to be controlled. Thanks to power monitoring systems measuring at many different places through PLC without any additional communication lines could allow a continuous monitoring of the PQ (Power Quality) [ 10 ]. A huge issue is also monitoring of power quality in a building complex of a critical infrastructure (e.g., a hospital complex). BPL is a suitable and complementary solution to LTE for connection of a PQ monitor measuring according to EN 332000–7–710 and EN 50160. Connection of BPL and a PQ monitor provides a system which ensures increasing of power supply quality, continuity of transition to backup power supply in case of natural disasters, fluctuations in the energy network or other abnormal influences. This solution is important especially for critical infrastructure facilities, whose longer disconnection from the network can have fatal health consequences [11]. Electric Vehicle : The EV (Electric Vehicle) charging uses PLC to manage the communication between the vehicle and the charging post [ 12 ] based on the Combined Charging System (CCS) specification [ 13 ]. HomePlug AV or HomePlug Green are considered in CCS deployments. Nowadays, there is for example a huge deployment of the Ionity company based on CCS with HomePlug Green [14]. Micro Grid and Distribution Generation : Typical future smart Commercial Buildings will be equipped with renewable sources, such as solar panels, small wind turbines, natural gas cells, energy storage, battery systems and combined heat and power to allow the users to generate electricity to the grid. In addition, emergency backup generation, capability of demand response and HVAC (Heating, ventilation and air conditioning) will be considered [ 15 – 17 ]. These Micro Grid and Distribution Generation (DG) required Sensors 2021,21, 240 3 of 17 new advanced applications with more bandwidth and higher data rates and fulfilling security requirements. The key questions for a discussion about Smart Building based on BPL are the following: • Is the throughput on the application layer sufficient for the applications in discussion? • Is the throughput on the application layer sufficient for the cyber security requirements? • Will the throughput on the application layer be sufficient for the applications in discussion for the worst case scenario? • Will the throughput on the application layer be sufficient for fulfilling the standard TR 61850–90–12 (Wide area network engineering guidelines)? (Note that IEC 61850 and TR 61850–90–12 provide the average throughput of up to 2048kbps. Furthermore, this standard provides the required availability of 99.9% and the minimum delay limit was set at 1000ms for one transmission direction.) • Could BPL be considered as communication technology for monitoring of the power quality in the building complex of a critical infrastructure (e.g., a hospital complex)? The article is divided as follows. In the first part, Section 4, we propose the reproducible and repeatable methodology and introduce a test bed. In the second part, Sections 5and 6 , the results of measurements and performance tests for the laboratory environment and the real field test are introduced. Finally, a comparison of different technologies is carried out and the summary and discussion are presented. 2. Related Works For real implementation and roll-outs of BPL in Smart Home and Smart Building, it is not commonly known whether the throughput of BPL is guaranteed to be sufficient for the applications in discussion. From the point of view of new applications for DG management, EVs and battery chargers and with the bandwidth necessary for keeping personal data secure, it is necessary to know the exact values of the throughput for a stable and robust (against interference) BPL communication. Many researchers conducted their studies on BPL throughput in terms of its PHY (physical layer) throughput, but very few of them focused on the exact conditions or the worst-case scenario and application throughput. Of the published works about BPL throughput on PHY or application layers, three types of methods were recognized: laboratory, simulations and real measurements. These types of methods are used separately. Our research focuses only on comparison of laboratory measurements with real measurements in the field. An overview of related works is summarized in Table 1and deeply discussed in the following paragraph. According to related works summarized in Table 1, there are several results of PHY throughput measurements, laboratory measurement and throughput simulation. The laboratory measurement together with field measurement for application throughput is missing. Therefore, this article focuses on throughput measurement on the application layer for laboratory topology together with field measurement for verification of laboratory results. Sensors 2021,21, 240 4 of 17 Table 1. Summary of related works. No. Authors Year Method Used Layer Standard Throughput [18] G. López et al. 2019 theoretical PHY max HP AV 200Mbps [19] Hashiesh, Fahd 2009 measurement PHY Corinex 12–26Mbps [20] Horvat, Balki´c, Zadar 2012 measurement Transport HP AV 30–35Mbps [21] Castor, Natale, Silva, Segatto 2014 measurement PHY undef 50–120Mbps [22] Tomimura, Neto 2008 measurement Transport HP AV 5.8–21Mbps [23] Cui, Lio, Cao, Xu 2018 simulation PHY undef up to 1Mbps [24] Sangsuwan et al. 2014 measurement Transport HP GP 0.88–3.3 Mbps [25] Lee et al. 2003 measurement Application HP AV 1.6–5.3Mbps [26] T. Matsuo, S. Maekawa 2005 measurement PHY CE Marking 45–100Mbps [27] Schwager et al. 2005 simulation PHY undef 190.6Mbps [28] Piñero et al. 2014 simulation Transport HP AV 10–75Mbps [29] Nico Weling, Neda Nazari 2011 measurement PHY HP AV 11Mbps [30] S. Sasikumar, S. Narayanan 2015 simulation PHY undef 180Mbps [31] Moises V. Ribeiro et al. 2015 measurement Application undef 1.23–5.15Mbps [32] Anton. G. Merkulov et al. 2019 measurement Transport HP AV about 24Mbps [33] Fujdiak et al. 2018 measurement PHY HP AV2 800–900Mbps [34] Mizutani et al. 2011 measurement PHY HD-PLC over 63Mbps [35] Orgon et al. 2019 measurement Transport HP AV2 622–766Mbps [36] Osman, Nisar, Altrad 2014 measurement Transport HP AV 95.14Mbps [37] Arab, Karimi, Safavi 2016 simulation Application HP AV 23Mbps [38] Hallak, Berners and Mengi 2020 measurement Transport ITU-T G.hn 95.5Mbps [39] IEEE standard 2019 theoretical PHY IEEE >100Mbps [40] IEEE standard 2018 measurement Transport EV PLC 48 Mbps López et al. [18] summarized BPL standards from DS2 to current Gh.n and IEEE 1901 and introduced the theoretical PHY throughput for ideal conditions. In [ 19 ], measurements with Corinex AV 200 (PHY throughput 200Mbps) was carried out with the result of throughout 12Mbps without filters and 26 Mbps with filters for in-home scenario with typical appliances (TV, PC, refrigerator). Horvat et al. [20] described laboratory measurements with PLC adapters with the HomePlug AV standard. At a distance of 50 m, the adapters reached an average throughput of 30–35Mbps. Castor et al. [21] used BB-PLC modems for onshore oil and gas industry applications on MV line. Modems worked in the spectrum 2–32MHz, but the standard is not defined in the article. The throughout is 50–120Mbps. Tomimura and Neto [22] described field measurements on a low voltage overhead power line with a length of 240 m using an adapter with the HomePlug AV standard. The throughput on the transport layer was in the range of 5.8–21Mbps . The authors of [ 23 ] simulated the topology of a distribution network in which the Carrier-Sense Multiple Access (CSMA) is commonly used. In the simulation, they proposed an improved adaptive p-persistent CSMA protocol based on the dynamic game optimization. The average bandwidth usage is improved by 89.2%. The throughput in the simulation is up to 1Mbps. Sangsuwan et al. [24] also focused on laboratory measurements of throughput. The measurement was performed at a distance of 100 m with and without interference. Lee et al. [25] presented simulation and real measurements. The measurements were performed at a point-to-point distance of 2–70 feet and the range was 1.6–5.2Mbps on the HomePlug AV standard. In [ 26 ], approximately 45–100Mbps was measured between Sensors 2021,21, 240 5 of 17 distribution stations in the 8–34MHz frequency range and 20–65Mbps at the frequency of 2–12 MHz in a building. Schwager et al. [27] presented a simulation of a potential broadband PLC system with the frequency range 4–30MHz, 1728 carriers, Forward Error Correction (FEC) coding and with Additive White Gaussian Noise (AWGN) at 26MHz. The result of the simulation is PHY throughput 142.9Mbps with 64QAM (Quadrature Amplitude Modulation) 190.6Mbps (256QAM) and 238.2Mbps (1024QAM). Piñero et al. [28] presented a simulated comparison between the standard HomePlug AV and HomePlug AV with the Greatest Common Tonemap (GCT) algorithm, which is a simple multicast algorithm occasionally used in wireless networks. Throughput in the topology with ten clients was 10Mbps with HomePlug AV and 75 Mbps with used GCT algorithm. Statistical evaluation of 55 million PLC channels and topology measurements by more than 75,000 end users was described by Weling and Nazari [29] . The largest drop in throughput to 11Mbps was at approximately 6PM. This may be due to the switching of a large number of electrical devices, such as televisions and lamps. Sasikumar and Narayanan [30] described the simulation and the advantages of incremental bit reading with a multiwire PLC. Better performance in terms of the coarse bit rate was achieved with multi-wire bit-read PLCs, rather than with two-wire bit-read PLCs. Maximum transmission speeds of around 180Mbps and 230Mbps were obtained for two-wire and multiwire PLCs with a transmission power of − 55dBm/Hz. Real measurements from the city of Juiz de Fora in Brazil [31] showed a throughput of 1.23–5.15Mbps. The connection can be established only in a distance of 300 m. Merkulov and Shuvalov [32] presented a practical example of a HomePlug AV modem application in the unique task of IP video signals transmission through a power line with the length of more than 700 m . The Transmission Control Protocol (TCP) throughput of the BPL adapter fluctuated within 800–900Mbps . The maximum speed guaranteed by the manufacturer is up to 1200Mbps [33] . Mizutani et al. [34] described measurements performed using broadband modems with the HD-PLC (High Definition Power Line Communication) standard with a maximum throughput of 220Mbps. The result of measurements in home electrical network was a throughput over 63Mbps at 50% of sockets in the house. Orgon et al. [35] presented the results of throughput measurements using a modem with the HP AV2 standard in real home electrical network. In a topology with connected appliances, the installed modems reached transmission speeds of 622–766Mbps. Osman et al. [36] focused on experimental measurements in a real home installation in Malaysia. They used modems with the HomePlug AV standard and iPerf3 software. The result of this measurement is an average throughput of 95.14Mbps between modems on the same phase with a throughput deviation of 62%. The simulations performed by Arab et al. [37] focus on quality of services testing. Testing took place in several different scenarios with different parameters set. The best results were achieved with the acknowledge timeout parameter set at 200us and the final throughput was 22Mbps. Hallak et al. [38] presented measurements with a BPL modem, which are part of the ITU-T G.hn standard. The transmission speed reaches 95.5Mbps; in the case of using a repeater, the speed is reduced to 48Mbps. The IEEE Std 1901–2010 [ 39 ] standard defines high-speed communication equipment through power lines of more than 100Mbps at the physical layer. At the same time, transmission frequency is up to 100MHz. Mahmood et al. [41] described the key issues associated with broadband communication, including attenuation, interference and reflection, noise and safety. Attenuation has a big impact on communication; the signal power is decreased when increasing the distance. The signal is attenuated with increased distance and frequency, while the cable loss causes an increase in signal attenuation. There are many different signals on power line networks, but, for communications, all signals except communications signals are considered interference or noise. Noise is one of the most important challenges facing PLC technology, where noise occurs from internal and external sources. In the end, there is security. It also needs to be addressed, even though the PLC technology is located on the power line. Another use of PLC technology can be in the principle of partial discharge detection. The authors of [ 42 , 43 ] pointed out the effect of a partial discharge on physical speed. In the normal state, the physical speed Sensors 2021,21, 240 6 of 17 was approximately 170Mbps; when partial discharges were injected, the speed dropped to 100Mbps. The technology can be used as a diagnostic tool. 3. Motivation and Goals According to results of achievable throughput analyzed in Section 2, the performance possibilities of BPL for implementation in Smart Building are not clear. New advanced applications, such as DG management and EVs or battery chargers, require more bandwidth and higher data rates. New security requirements also require more bandwidth to fulfill security implementations necessary for operations connected to payment and billing (e.g., EV applications), critical infrastructure (remote switching, for example smart meter disconnection) or according to the GDPR (General Data Protection Regulation) law (essential data of users). The main motivation of the article is to introduce exact values of performance and other Quality of Services (QoS) parameters for the consideration of implementing BPL technology in the Smart Building. The novelty of the research introduced in the article is also a new design of the BPL model integrated in a power plug. The integrated BPL model is designed directly for Smart Homes and Smart Building where there is a problem with space and also the need for a nice look. The main goals of the article are the following: • Introduce possible throughput of different BPL solutions for different conditions (noise and attenuation). • Provide measurements and a repeatable methodology for new BPL solutions and the research community. • Compare laboratory results with real field measurements. • Provide throughput on the application layer, as the PLC network performance is usually described using the phrase “up to” or introduced on the physical layer. • Provide throughput for the “worst case“ scenario with high noise level. • Define and quantify high data rates and high-level security. • Present a BPL modem integrated into power plug. Why BPL and why high bandwidth requirement? BPL and high bandwidth requirements are considered due to a large amount of overhead caused by cybersecurity and protocol overhead. For example, in the BPL rollout in Germany (Mannheim model city based on BPL communication [ 7 ]), it is mandatory to consider British Standards Institution (BSI) security requirements with TLS (Transport Layer Security). TLS requires 4–7KB for connection establishment and 21B for every packet [44]. TLS together with consideration of the DLMS/COSEM (Device Language Message Specification/Companion Specification for Energy Metering) provide for the register value of data transfer for billing (register size of 2B) the total amount of approximately 2KB of overhead of all OSI (Open Systems Interconnection) layers and security issues [45]. 4. Methodology The Request for Comments (RFC) 6349 methodology was considered for easy replication in different laboratories or different PLC devices. In addition, RFC 6349 represents TCP based measurements which are necessary for TLS connections. In comparison with different methods (e.g., a TCP throughput methodology is also available in EXFO FTB–Pro testers), RFC 6349 provides lower throughput, because this method considers the worst condition on the power line (the windows size was set-up according to RTT (Round-Trip Time) measured before transmission). RFC 6349 also considers TCP efficiency which counts re-connection or new establishment of TCP connection. The RFC 6349 methodology is composed of the following phases: • The Maximum Transmission Unit (MTU) of the line detection • RTT measurements and calculation of the optimal window for the TCP protocol • TCP throughput testing, TCP efficiency (how many bytes were re-sent) testing and delay of buffer (how many times did the RTT increased) testing Sensors 2021,21, 240 7 of 17 5. Field Measurement Real testing was performed in cooperation with the company E.ON (Brno, Czech Republic), which is a distributor of electricity in the Czech Republic. Testing was performed using BPL modems, which are based on the IEEE 1901 standard and use the 2–30 MHz frequency band with FFT OFDM (Fast Fourier Transform Orthogonal Frequency-Division Multiplexing) on the physical layer. The tested topology was a direct connection of two transformer stations. The distance between the stations was 105 m. The connection took place via an underground cable line of the AYKY (cable made of aluminum for fixed installation) type with a cross-section of 185 mm2. The operating low voltage of the threephase distribution was 0.4kV. According to Geographic Information System (GIS), it was found that the cabling was installed in 1992. An overview of the parameters is given in Table 2. Table 2. Basic description and parameters of power line. Operating Voltage 0.4kV Type of power line underground power line Material AYKY Conductor cross-section 3 ×185 + 95 Length according to GIS 104.76m Year of construction 1992 The measurement procedure first defines the topology (Figure 1) that also contains the route parameters (line length, cable type, age, etc.). It is also necessary to take into account the measurement time, due to the nature of the communication technology. As part of the measurement, short-term tests were performed, where the duration of the measurement was always 10 min in the approximate time between 9AM and 11 AM. DS1 DS2 AYKY3x185+95 BPL(LV) 105m Figure 1. Diagram of measured topology. EXFO FTB–Pro instruments were always used for the measurements. They were connected to the BPL modem via the Ethernet interface. RFC 6349 and TCP throughput measurement methodologies were used. The achieved values of throughput (transmission rate at a given communication layer) are always the average value for the entire measurement period. Two methods were considered for measurement: • RFC 6349: The main advantage of the Internet Engineering Task Force (IETF) method RFC 6349 (referred to as RFC 6349) is the fact that it uses the TCP protocol for the measurement itself, which is now predominantly used for non-real-time communication on the Internet. • TCP throughput: The main advantage of this methodology is an algorithm that works with the so-called TCP window size, which it adapts during the entire test. In the case of IETF RFC 6349, the size of the TCP window is determined when the test is initialized. The TCP throughput testing methodology uses a reliable TCP protocol for testing, similar to RFC 6349. The main difference compared to RFC 6349 is that the size of the TCP window can be defined in the allowed range (set by the tester). The methodology is Sensors 2021,21, 240 8 of 17 intended to allow more accurate throughput testing, due to more flexible work with the TCP window size, but, for BPL/PLC variable behavior (throughput fluctuations), this leads to extreme jumps (window size of hundreds B to MB). TCP throughput uses an algorithm that works with the size of the TCP window, which it adapts throughout the test. RFC 6349 specifies the size of the TCP window when the test is initialized. This window determines the amount of data that can be transferred. Its size is therefore always related to the capacity of the network, which, as a rule, it must not exceed due to error-free and efficient message delivery. Furthermore, a reception window is used, which must be optimal with respect to the performance of the receiver, in order to process the received data. Proper control of this window can therefore significantly affect the results of the measured communication. Table 3summarizes communication directions L → R (local to remote) and R → L (remote to local); TCP window indicates the total maximum window followed by the number of connections and KB per connection in parenthesis as “(n conn.@ n KB)”; Ideal L4 means the ideal TCP throughput metric; Actual L4 shows the average of the actual TCP throughput metric the achieved with the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol using the RFC 6349 methodology; TCP efficiency indicates the metric based on transmitted and re-transmitted bytes; Buffer Delay indicates the percentage metric which represents the increase in RTT during a TCP Throughput test versus the Minimum RTT; and Minimum RTT is the minimum time between the first bit of a segment sent and the last bit of the corresponding acknowledgement. The average throughput determined by RFC 6349 was 22.2Mbps and in the opposite direction 20.9Mbps. Compared to the TCP throughput methodology, a higher throughput was achieved, which reached 33.375Mbps for both directions and with the average RTT response of 46ms. The difference in throughput is due to the different behavior of the TCP window size. With the RFC 6349 methodology, the value of the window size is determined before the measurement itself, but the TCP throughput methodology adjusts the window size as needed during the measurement. For this reason, higher values are achieved. The results show very high values of TCP throughput. This is due to the high-quality cable connection, which was built in 1992. The cable did not degrade during that time, nor did moisture enter it. In addition, the cable does not contain any connectors or taps that could have an adverse effect on the communication. There are not many similar measurements. Hofer [46] measured in three different TCP window sizes using the iPerf3 tool. The topology was then point-to-point. Testing in the field produced results with a median of 11.614Mbps between 700B and 1300B. Table 3. Achieved results of RFC 6349 methodology. Direction TCP Window Ideal L4 (Mbps) Actual L4 (Mbps) TCP Efficiency (%) Buffer Delay (%) Minimum RTT (ms) L→R37.9KB (2 conn. @ 18.4KB) 93.9 20.9 100 379.53 3.235 R→L37.9KB (2 conn. @ 18.4KB) 93.9 22.2 100 350.99 3.235 6. Laboratory Measurement Laboratory measurements dealt with testing of selected broadband PLC adapters according to RFC 6349 method. The principle of testing RFC 6349 testing was described in the Section 4. PLC adapters from different manufacturers with different throughput, frequency range, integrated circuits and different standards were considered for testing. Table 4shows the list of used adapters. Sensors 2021,21, 240 9 of 17 Table 4. Tested broadband PLC adapters. Manufacturer: Cisco Zyxel Devolo DS2 Industry RAKwireless Model: PLE500 PLA5206 Magic 2 - LX200V30 Chipset QCA7450 BCM60333 88LX5152 DSS95X AR7420 Standard: HP AV2 HP AV2 G.hn DS2 HP AV Bandwidth [MHz]: 2–68 2–86 2–100 2–34 2–68 PHY speed [Mbps]: 600 1000 2400 200 500 ETH Interface [Mbps]: 1000 1000 1000 100 100 Security: 128b AES 128b AES 128b AES 256b AES 186b AES 6.1. Topology Of Measurement The topology created for laboratory measurements is shown in Figure 2. This topology provides a repeatable environment for easy, time-efficient and low cost evaluation of different BPL solutions. The measured broadband modems were connected through a separated and isolated 230V AC electrical network. The measurements were performed at distances of 5, 55 and 105 m for all tested modems. Network analyzers EXFO FTB-1 PRO were used for testing according to the RFC 6349 methodology. The RFC 6349 was considered for simple guidelines, which ensure repeatable methodology for new BPL solutions or for comparison of our results by the research community. Broadband noise from the PROMAX PROPOWER-1 generator was also injected into the transmission path using the coupler. The basic parameters of this generator are shown in Table 5. The frequency range of this generator is 1–50MHz, but the noise distribution is not uniform in the whole frequency spectrum and reaches its highest noise values in the range of 2–20, 28–35 and 43–50MHz. For laboratory measurements, the power of the generator was set to 5% corresponds to the generator switched on, 50% to half the generator power and 100% to the full generator power, which, according to the values measured by the spectrum analyzer, correspond to noise powers of 3, 5 and 11dB. The setting of the three noise levels corresponds to conditions with low, medium and high levels of interference. From the topology point of view, the whole measurement took place in three scenarios: • Cable route length 5 m—noise generator power level 5%, 50% and 100%. • Cable route length 55 m–noise generator power level 5%, 50% and 100%. • Cable route length 105 m—noise generator power level 5%, 50% and 100%. The measurement was performed with the following rules: • When the distance between modems changed, the connection was always re-established and another measurement was then performed. • Noise performance increases always after measuring the previous value. • After increasing the noise value, there was 30 s of waiting for the connection stabilization. The main parameters that have an impact on communication in the test topology: • Distance between tested modems • Frequency bandwidth of tested modems • The amount of interference noise in the transmission path Sensors 2021,21, 240 16 of 17 21. Castor, L.R.M.; Natale, R.; Silva, J.A.L.; Segatto, M.E.V. 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