Session ISP-Welcome

ISPLC Welcome Address

8:30 AM — 9:00 AM CEST
Oct 26 Tue, 2:30 AM — 3:00 AM EDT

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Session S1

Session 1: Modulation and Signal Processing for PLC

9:45 AM — 11:05 AM CEST
Oct 26 Tue, 3:45 AM — 5:05 AM EDT

Comparison Between Different Peak-To-Average Power Ratio Reduction Techniques

Philipp Horwat and Dennis Stamm (Hochschule Ruhr West, Germany); Gerd Bumiller (Hochschule Ruhr West & University of Applied Sciences, Germany)

Orthogonal Frequency Division Multiplexing (OFDM) leads to a high Peak-to-Average Power Ratio of the signal. This requires high power reserves at the transmitter and reduces the capabilities of impulsive noise cancellation at the receiver. To overcome this drawback, several techniques exist to lower the Peak-to-Average Power Ratio of the signal. This paper compares nine different techniques regarding their results in Peak-to-Average Power Ratio reduction, bit error rate increase, notch depth, out-of-band distortion, signal power increase, loss in data rate and computational complexity. Five techniques provide good results, but each of them has a unique drawback, so it is still required to pick the best one during individual OFDM system design.

Collections and comparisons of different PAPR reduction techniques already exist. However, we did not find a comparison that discussed the impact of those techniques on notch depth. Additionally, none of the found comparisons presented actually measured parameters but were limited to general statements. Last but not least, in papers presenting new PAPR reduction techniques not all decision parameters are discussed.

Power Line Communication for Grid Monitoring: A Prototype Based on Software Defined Radio

Stephan F. Pfletschinger (Offenburg University of Applied Sciences, Germany); Jens Lottermoser (Hochschule Offenburg, Germany); Joerg Bausch (Universität Karlsruhe, Germany)

We describe a prototype for power line communication for grid monitoring. The PLC receiver is used to gain information about the PLC channel and the current state of the power grid. The PLC receiver uses the communication signal to obtain an accurate estimate of the current channel and provides information which can be used as a basis for further processing with the aim to detect partial discharges and other anomalies in the grid. This monitoring of the power grid takes advantage of existing PLC infrastructure and uses the data signals, which are transmitted anyway to obtain a real-time measurement of the channel transfer function and the received noise signal. Since this signal is sampled at a high sampling rate compared to simpler measurement sensors, it contains valuable information about possible degradations in the grid which need to be addressed. While channel measurements are based on a received PLC signal, information about partial discharges or other sources of interference can be gathered by a PLC receiver in the absence of a transmit signal. A prototype based on Software Defined Radio has been developed, which implements the simultaneous communication and sensing for a power grid.

A Simple Physical-Layer Key Generation Scheme for Power-Line Transmission

Werner Henkel and Ha Kim (Jacobs University Bremen, Germany); Abderraheem Turjman (Hochschule Bremen / Jacobs University Bremen, Germany); Mathias Bode (Jacobs University, Germany)

We have already shown in earlier publications that reciprocity of power-line channels, expressed by, e.g., \(S_{12} = S_{21}\) using scattering parameters, can provide the desired common randomness for physical layer key generation. We had used minima or maxima of those transfer S-parameters to select possible keys. The tree-like power-line topology with bridge taps that are imperfectly terminated, possibly just left open, provide the means to create deep notches and, of course, local maxima in between. Using those positions, however, does not work well under noise conditions and power-line channels are know for their stationary and non-stationary disturbances. Minima will just be filled by noise, maxima that are wider than the minima experience a ripple thereby making it difficult to obtain identical positions under uncorrelated noise at the legitimate users' ends. To solve this issue, in here, we propose to instead use the amplitude values at maxima positions. Disturbances there are directly related to the noise amplitudes. High maxima and corresponding key sequences resulting from amplitude quantization of the transfer characteristic are then less error-prone. Further improvements to reduce noise effects are obvious, just like averaging measurements, smoothing over frequency, or just only accepting measurements above certain thresholds. Quantization of amplitudes is carried out in log domain and mapping to bit patterns is realized in a cyclic fashion together with Gray coding. Key reconciliation is realized by shifting measurements into the middle of quantization intervals.

A Subcarrier Permutation Scheme for Noise Mitigation and Multi-Access in Powerline Channels

Oluwafemi Ibrahim Kolade (University of the Witwatersrand, South Africa); Adnan M. Abu-Mahfouz (CSIR NextGen Enterprises and Institutions, South Africa); Ling Cheng (University of the Witwatersrand, South Africa)

Multiple codewords of non-binary permutation codes, selected with the maximum Hamming distance between them, is used to increase the spectral efficiency of the multicarrier orthogonal frequency division multiplexing (OFDM) with Mary frequency shift keying (MFSK) scheme. In addition, the codes can assist with the selection of a set of unique subcarrier permutations. The subcarrier combination makes the coded scheme suitable for a multicarrier, multi-user access technique. Over a powerline communication channel with impulsive noise, the peak-to-average power (PAPR) of the coded and uncoded schemes are compared. In addition, the symbol error rate (SER) performance of the single user and multi-user schemes are shown for different threshold detection values and shared power allocation in the
multi-user scheme. The SER performance is based on minimum distance, hard-decision, joint subcarrier decoding, with results showing a degradation in the multi-user, multiple permutation scheme. This performance is further improved using a soft-decision decoder which uses the soft samples from the output
of the channel.

Session Chair

Sicong Liu (Xiamen University, P.R. China)

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Session S2

Session 2: Noise Mitigation and Modelling

11:35 AM — 12:55 PM CEST
Oct 26 Tue, 5:35 AM — 6:55 AM EDT

PLC-xDSL Dynamic Interference Mitigation

Andreas Engelen (Devolo AG, Germany); Nico Weling (devolo AG, Germany)

In this paper, we will present the results of a field trial based on a PLC to xDSL Dynamic Interference Mitigation (DIM) mechanism. The DIM algorithm, which has been included into the firmware of commercial in-home PLC devices, aims to improve the ability of a peaceful coexistence between PLC and xDSL systems. Further, we will present a laboratory measurement test system, which has been set up to debug and proof the concept of the DIM feature. We will look to the laboratory measurement test results, which have been studied prior rolling out the DIM enabled firmware for the field trial. The results from field study will show that xDSL lines, which are suffering from PLC signal ingress, become more stable and better performing when implementing the DIM mechanism. It will also be shown that only a small percentage of xDSL connected end-users are affected by signal ingress from PLC devices into the phone-line.

Design and Development of a Multi Port Powerline Communication Network Analyzer for Measurements of Low Voltage Grid Components

Axel Staubach and Holger Hirsch (University of Duisburg-Essen, Germany)

To accurately determine and estimate the channel properties of Powerline Communication (PLC) structures in advance requires a comprehensive understanding of the physical properties of the individual components of the existing infrastructure. By measuring the attenuation, impedances and noise levels within the power grid network a deeper knowledge of the influence of different components and the connection quality between PLC devices can be evaluated. This publication gives an overview of the challenges to measure and obtain this critical data. By designing a full automatic multiport network analyzer with PLC capabilities and remote access a measurement system is created to gain long time data of the physical properties in the low voltage power grid systems. By using standard commercial components, developing an analog front end (AFE) and programming of a pseudo real time environment for the firmware an affordable and fast option to classical network analyzers can be constructed. Finally first results of a real network topology measured with this system are presented.

Pilot-Free Channel Tracking for In-Band Full-Duplex Broadband Power Line Communications

Vitali Korzhun and Andrea M Tonello (University of Klagenfurt, Austria)

In-band full-duplex (IBFD) is an attractive technology in telecommunications since it can improve spectral efficiency and data rates. However, IBFD is challenging since its implementation requires a complex architecture and an advanced algorithm for echo (self-interference, SI) cancellation. In addition, IBFD deployment is especially challenging in broadband power line communication (BB-PLC) due to channel frequency selectivity caused by multipath propagation, impedance mismatches, and time-variant behavior. Such PLC channel conditions require the ability of the system to track channels and adapt to their changes. In this paper, we propose a pilot-free channel tracking algorithm for IBFD 2-by-2 multiple-input multiple-output (MIMO) BB-PLC. We demonstrate the ability to obtain initial estimates of the channels and SI responses using a half-duplex training phase. Then, we use a data decision-driven approach for channel tracking. The tracking ability of the system is evaluated using the average error vector magnitude (AEVM), a metric that characterizes the equalized constellation quality at the receiver. Our data-driven approach shows good tracking ability with 75% of the subcarriers being updated at each data symbol.

Mitigation of Coloured Impulsive Noise in Ofdm Receiver

Sebastian Schaffenroth (OTH East Bavarian TechnicalUniversity of Applied Sciences & Aia Automation Institute, Germany); Hans-Peter Schmidt (OTH East Bavarian Technical University of Applied Sciences & aia Automation Institute, Germany); Alexander Koelpin (BTU & Chair for Electronics and Sensor Systems, Germany)

Power line communication (PLC) in factory and process automation requires real time capabilities. Therefore, robustness is a key feature in industrial communication. For such power line communication, a common scheme is Orthogonal Frequency Division Multiplexing (OFDM). The major source of noise are variable speed drives that generate impulsive noise. OFDM spreads impulsive noise on several sub-carriers and weaken its impact on BER. It is known that with decreasing signal-to-noise ratio (SNR) the BER of all affected sub-carries is rising. There are several non-linear strategies like clipping, nulling and hybrid clipping-nulling to mitigate this impulsive noise. So far, the level of the received samples is used as filter-criterion for these filters. We propose a novel mitigation scheme for coloured impulsive noise based on finite impulse response (FIR) filters. Simulations with coloured impulsive noise show the decreased BER with this novel approach. Furthermore, we measure impulsive noise from variable speed drives and use actual readings to verify the effectiveness of the proposed mitigation scheme.

Session Chair

Gerd Bumiller (Hochschule Ruhr West, Germany)

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Session S3

Session 3: Hybrid Technologies & Machine Learning Applications in PLC

3:05 PM — 4:25 PM CEST
Oct 26 Tue, 9:05 AM — 10:25 AM EDT

On the New Developments in ITU-T Standard: Use Cases, Requirements, and Solutions

George Hallak (Devolo AG, Germany); Marcos Vazquez (MaxLinear, Spain); Anil Mengi (Devolo AG, Germany); Livia Rosu (MaxLinear, Spain)

ITU-T technology is a well-known standard in the field of home networking transmissions. For a long time, it has been used a high-quality link for video services (e.g., IPTV) and as a connectivity extender (cable replacement). However, the flexibility of the technology allows to use it in new heterogeneous approaches for home networking and in new contexts of application. These new uses of the technology are driving evolutions of the standard. This paper draws the general picture of the status of ITU-T technology and the future trends that are expected in the home distribution and that may impact the role of technology in the home networking. Different use cases, requirements and optimizations are discussed. This paper presents some of the technical challenges that the industry will face in the coming years. These technical challenges should be addressed by the relevant standardization groups with the help of academia.

Capacity Learning for Communication Systems over Power Lines

Nunzio Letizia and Andrea M Tonello (University of Klagenfurt, Austria)

The development of power line communication (PLC) systems and algorithms is significantly challenged by the presence of unconventional noise. The analytic description of the PLC noise has always represented a formidable task and less or nothing is known about optimal channel coding/decoding schemes for systems affected by such type of noise. Recently, deep learning techniques have shown promising results and a wide range of opportunities in areas where a mathematical description of the physical phenomenon is not attainable. In this sense, the complex nature of the PLC network renders its medium characterization extremely challenging and therefore appealing for a data-driven approach.

In this paper, we present a statistical learning framework to estimate the capacity of additive noise channels, for which no closed form or numerical expressions are available. In particular, we study the capacity of a PLC medium under Nakagami-$m$ noise and determine the optimal symbol distribution that approaches it. We lastly provide insights on how to extend the framework to any real PLC system for which a noise measurement campaign has been conducted. Numerical results demonstrate the potentiality of the proposed methods.

A Seamless Broadband PLC-VLC Transmission: Performance Evaluation and Dimensioning

Yara Yaacoub (Institut National Des Sciences Appliquées & IETR, France); Fabienne Nouvel (INSA IETR RENNES, France); Jean-Yves Baudais (Univ Rennes, INSA Rennes, CNRS, IETR, France); Sylvain Haese (IETR-INSA Rennes, France)

As the LED lamps are naturally connected to the powerline, the integration of powerline communication (PLC) and visible light communication (VLC) seems to be trivial. In fact, cascading VLC to PLC is not very simple especially because their channels are not designed for communication purposes. The PLC and VLC channels suffer from severe attenuation with increasing frequency. Thus, the cascading of these two channels will lead to a very limited bandwidth which can complicate the PLC-VLC integration. Few experimental studies are carried out to prove the feasibility of PLC-VLC integration, particularly those based on the amplify and forward (AF) relay. Therefore, PLC-VLC broadband transmission is demonstrated in this paper without making any changes to the transmitted PLC signal before traveling through the optical system. A theoretical study is also carried out to design LED luminaires capable of providing both lighting and communication. This study extrapolates the experimental results of the small-scale PLC-VLC testbed to design a PLC-VLC system for typical indoor applications.

Performances of G3 PLC-RF Hybrid Communication Systems

Alfredo Sanz (University of Zaragoza & Microchip Crop, Spain); David Sancho (Microchip Technology Inc., Spain); Jose Carlos Ibar (Microchip Technology Zaragoza Inc., Spain)

In this paper the main changes of the new version of the G3 standard are reviewed, especially its evolution to a hybrid system combining PLC and RF. In particular, current simulation results comparing the performance of the system in three AMI (Advanced Metering Infrastructure) use cases are presented. The first one is an environment in which all nodes are PLC and the PLC noise level allows connectivity in all areas of the site. The second one is an environment in which all nodes are PLC+RF and the PLC noise level does not allow connectivity in some areas and the system needs to switch to RF. The third one is an environment in which half of the nodes are PLC+RF and the other half are RF only. This would be the situation of a system with electricity meters, which are hybrid PLC+RF, and gas or water meters, which are RF only. To evaluate their performance, some KPIs (Key Performance Indicators) suitable for these applications are introduced. We will also explain other improvements of the new version such as Broadcast optimization, Cluster forwarding scheme and Adaptive power mechanism.

Session Chair

Francisco J. Canete (U Malaga, Spain)

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