RICERCA ITALIANA     

Design and experimentation of naval PowerLine Communications

Università di Pisa

Abstract

The objective of this project is the development and experimental test of an innovative system for naval powerline communications (PLC). It will be investigated the reliability and efficiency of the transmission of command and control data of electrical equipment on ships and pleasure craft, exploiting the powerline cable normally used for the transmission of electric energy instead of a specially dedicated cable system. In such a way, the number of the cables on board ship will be drastically reduced, saving both space and the designing costs of the wiring and electrical installations. This solution is an advanced innovative technique with respect to the currently used solutions on board ships where many dedicated cables are necessary to remotely control the electronic and electromechanical devices that are constantly increasing on board of modern ships.
The project is characterized by strong complementary activities that need synergical expertise apported by the five Research Units (UR). Working in strict cooperation they will be able to develop the research activities by achieving intermediate and final objectives of the project. The project activities will be divided into seven Working Groups (WG), each of them leaded by a URR (identified on the basis of their skills characteristic) that will be responsible of the development of specific tasks of the WG and of the objectives to be achieved according to an appropriate time schedule, articulated in order to achieve maximum efficiency of research.
Such management of the project clearly highlights the complementary and synergical characteristics of the research activities, according to a scheme already effectively implemented by the five UR in previous research projects, such as PRIN 2003, when they have proven their ability to create a cohesive and effective working group.
The basic part of the project is the experimental activity that will be carried out through the collaboration of a company in the nautical sector. Indeed, at the end of the design phase of the data transmission system (with all its components), its performance will be verified by experimental tests on board of nautical yachts.
These experimental activities will be possible thanks to the availability of “Benetti Yachts”, one of the leading companies in the production of yachts based in Livorno (Italy), which guaranteed its enthusiastic membership to the project. Staff of the "Benetti Yachts" will be involved with the RU of Pisa confirming the real interest of the companies in nautical sector in these problems both to reduce cabling costs and to increase the space for passengers on board.
The “Benetti Yachts” will provide the information necessary to properly design the system for data transmission that use the on board electrical installations. Furthermore, the company will place at the project's disposal both a yacht under construction, and a finished yacht, to allow to test the prototype of the data transmission system. <<<

Principal Investigator

Marco Raugi Università degli Studi di PISA

Research Objectives

In order to study and design a naval PLC system we have evidenced six main factors:
1- The definition of a suitable channel model to effectively represent the signal transmission in naval powerlines
2- Knowledge and classification of noise in the channel;
3- Power losses limitation in the coupling between transmitter/receiver and the channel;
4- knowledge of the variations of the channel during the transmission of data;
5- electromagnetic compatibility of the system;
6– Optimization of signal power to transmit the data.

The topic 1 has been introduced to obtain the best possible solution for the actual problems listed in the other 5 topics.

For each of the above described topic the project has specific targets

Topic 1
- Definition of measurable parameters that allow the channel characterization in a wide frequency range and in a number of operating conditions in a nautical environment. The parameter will be inserted in a theoretical model for the numerical simulation of the channel.
- To define procedures and techniques to measure the previously defined parameters
- To define a typical channel model for the numerical simulation of powerline communications
- Implement a channel model for its inclusion in a software simulator of naval powerline communications. This simulator will be used by the project working groups for their activities

Topic 2
- Classification of noise in naval powerlines in time and frequency domain
- To define a mathematical model of noise for insertion in a simulator for naval powerline communications
- To implement the noise model in a software simulator of naval powerline communications. This simulator will be used by the project working groups for their activities

Topic 3
- To develop suitable circuits for optimizing the coupling of transmitter/receiver and the transmission channel
- To define new coupling circuits with adaptive topology to follow the time variance of the transmission channel

Topic 4
To develop a real-time channel estimator able to follow the time variations of the frequency response of the transmission channel

Topic 5
To define suitable parameters for the description of radiated fields in terms of conducted signals in naval powerlines

Topic 6
To define optimization algorithms for bit-loading in naval powerline communications

In the last phase of the project experimental field trials aboard yachts of “Benetti Yachts” will be carried out.
To this aim the following targets are defined:
- Implementation of a naval powerline communication software simulator
- To develop a hardware prototype for naval powerline communications
- Experimental verification of the prototype on Benetti yachts <<<

First Results

As previously stated, in this project OFDM modulated signals will be considered. This technique is widely accepted as the most robust for signal transmission in frequency selective and time variant channels (see the Proceedings of IEEE ISPLC Conferences available on IEEEXplore or text books as K. Dostert "Powerline Communications" Springer-Verlag). Indeeed, powerlines behave as a tranmission channel very similarly to the wireless transmission channel. Then, the consolidated results obtained for that applications can ba adopted als o in the PLC environment.

Then, the efficiency of data transmission is mainly determined by five specific factors related to the components of the system:
1. the optimization of bit-loading algorithms;
2. limiting of power losses due to the coupling of transmitters and receivers with the channel;
3- knowledge and classification of noise in the channel;
4- knowledge of the variations of the channel during the transmission of data;
5- electromagnetic compatibility of the system.

To set up an innovative transmission system such as the one here proposed in a naval environment seven Working Groups (WG), each of them managed by a leader Research Unit URR (identified on the basis of its skill characteristics) have been organised. That way the above listed topics have been associated to different WPs with specific aims and targets.
WG 1 Channel Modelling

Partial predicted results
After 5 months (Check Point Phase 1): Meeting and technical report on transmission channel model studies. Planning of next activities.
After 8 months (End WP1): Meeting and technical report on the defined transmission channel model.
Report on the experimental measurements on Benetti yachts. Delivering to all Research Units of a software package for transmission channel simulation.

Innovation and application fields
The definition of measurable parameters to characterize signal transmission in powerlines is an innovative result in a nautical environment. Furthermore, these parameters will be defined in order to be inserted in a theoretical model of a typical naval powerline that will be used for PLC systems simulations.
In order to obtain this model the cooperation with “Benetti Yachts” will be essential. “Benetti Yachts” will provide the detailed electrical schemes of the power system and of the loads installed on its ships. By using these schemes a sample model for naval powerlines will be developed by considering the common features of different power system built at “Benetti Yachts”. This model will be also defined by statistically considering the different powerlines characteristics. The model would allow the simulation of the channel frequency response, reflections and distortions of the transmitted signals, impedance variations.
The theoretical model will be characterized by means of measurable parameters. This will allow the experimental validation of the capability of the model in predicting the characteristics of the transmission channels. The experimental validation of the characteristics predicted by the model will be performed on ships by “Benetti Yachts”.
The model will include, when possible, the experimental data taken on some of the more common electrical loads usually present in a ship, i.e. propulsion motors, cooling systems, lighting and entertainment systems for passengers and crew, devices in the kitchens and laundries. The characterization of these loads has never been reported in the bibliography.
These results are also very important for the activities of subsequent Wps for the reaching of their specific targets.

WG 2 Noise characterization

Partial predicted results
After 5 months (Check Point Phase 1): Meeting and technical report on noise model studies. Planning of next activities.
After 8 months (End WP2): Meeting and technical report on the defined noise model in naval powerlines.
Report on the experimental measurements on Benetti yachts. Delivering to all Research Units of a software package for transmission channel simulation.

Innovation and application fields
The identification and classification of noise in naval electrical power system has never been previously investigated. To obtain this classification the experimental tests are necessary. Then, cooperation with “Benetti Yachts” will be essential. A measurement campaign on ships at “Benetti Yachts” will allow the evaluation of the noise level associated with the more common loads connected to the system in different operating conditions. Successively, a mathematical model for naval powerline noise will be defined and inserted in a software simulator for the naval PLC system.
On the basis of the measured data a set of characteristic parameters of the noise will be defined in order to estimate its intensity and to characterize it both in the time and in frequency domain.
Neural networks and other identification and classification techniques (SVM, SOM, ICA, Fuzzy, etc), yet not used in this context, will be adopted by the involved research Units that has reached a good skill in using these tools in other areas.
Another significant result will be the inversion techniques to reduce the uncertainties due to errors in the measures or in the computations.

WG 3 Coupling circuits

Partial predicted results
After 5 months (Check Point Phase 2): Meeting and technical report on studied coupling circuits. Planning of next activities.
After 10 months (End WP3): Meeting and technical report on the defined coupling circuit.
Scheme of the circuit topology

Innovation and application fields
The development of coupling circuits between the transmitter and the receiver for PLC and the transmission channel with the objective of maximizing the power of the signal at the receiver is an innovative result in a nautical environment. It is of paramount importance to transfer the maximum allowed electric power to the receiver with a corresponding minimization of the power losses in the system components. Since it is not possible to modify the transmission channel, an efficient design of the coupling circuits is strongly required.
The first step will consist in the design of coupling circuits with frequency dependent output impedance that will be able to match the transmission channel transfer function. In this project a real time estimator of the transfer function (see WG4) will be defined. Then, by using the output from this estimator before the beginning of the transmission the coupler will be developed in order to realize proper output impedance matched with the transfer function of the channel.
The second step will concern the set up of a communication system between the estimator and the coupler in order to vary the impedance of the coupler according to the variations of the frequency response of the channel that are due to the connection or disconnection of the loads to the power grid. Subsequently the Research Unit will investigate the realization of coupler with variable topology in order to continuously follow the variation of the characteristics of the channel. Circuits with variable topology are circuits whose components values are electronically varied as function of external sources, in the case under examination output signals from the estimator. These results are definitively innovative in a nautical environment

WG 4 Channel estimator

Partial predicted results
After 5 months (Check Point Phase 2): Meeting and technical report on studied coupling circuits. Planning of next activities.
After 10 months (End WP4): Meeting and technical report on the defined channel estimator and related simulations.

Innovation and application fields

The development of an estimator of the time variation of the frequency response of the transmission channel is an innovative result in a nautical environment. The electrical devices are connected and disconnected from the naval power system in an unpredictable way. This causes an important variation with respect to the time of the frequency response of the transmission channel; some of the frequency bands used in the transmission can became at a given instant unavailable with a consequent reduction of the overall efficiency of the system. To avoid this loss of efficiency the transmission system should be able to move a set of sub-carriers from a sub-band to another in order to preserve the transmission rate. Innovative techniques based on the use of neural networks will be studied. These techniques use the useful transmitted data in order to accomplish this task with the higher speed. The usually neglected nonlinear loads present in the system will be taken into account with the aim of adjusting the neural network to their effects.
The UR of Bari will investigate an innovative technique based on the use of proper test signals. This technique is different from the previous one and its performance will be evaluated.
The combined usage of the two techniques will be investigated in order to increase speed and efficiency in the identification of the variations of the frequency response of the channel. The WG will end with the definition of experimental tests that will be performed on a real naval power system with the aim of validating the effectiveness of the proposed channel estimator.

WG 5 EMC

Partial predicted results
After 5 months (Check Point Phase 2): Meeting and technical report on studied electromagnetic compatibility effects. Planning of next activities.
After 10 months (End WP5): Meeting and technical report on the defined parameters for the characterization of radiated fields and related simulations.

Innovation and application fields

The definition of conducted parameters able to quantify the radiated electromagnetic fields in a naval PLC system is an innovative result.
The WG #5 will concern with the electromagnetic compatibility aspects related to the PLC systems. The evaluation of the electromagnetic fields in naval powerlines is not possible without the knowledge of the position and the section of the cables of the power system under study. Each ship has its power system and this prevent an a priori evaluation of the electromagnetic fields emitted by a PLC system. The innovative aspect of this WG is the design of a system that allows varying the power of the transmitted PLC signals in order to control the radiated fields of the power systems used for the data transmission. This adjustment will be performed by using a set of parameters, evaluated during the bootstrap of the PLC system, that are indicative of the emitted fields.

WG 6 Bit-loading optimization

Partial predicted results
After 5 months (Check Point Phase 2): Meeting and technical report on the studied bit-loading algorithms. Planning of next activities.
After 10 months (End WP6): Technical report on the defined optimized bit-loading algorithms.

Innovation and application fields

To optimize a PLC system by defining an optimized bit-loading algorithm for naval powerlines is an innovative result.
Indeed a bit-loading algorithm is not standardized yet. The main target of the WP is the implementation of new algorithms that allow overcoming the limitations of the traditional ones. A new formulation of the bit-loading problem will be proposed; this new formulation will take into account a number of aspects that because of their computational cost are usually neglected by the classical approach. The optimization problems will be expressed in terms of a multi-objective optimization; in this formulation the three main variables, namely the transfer rate, the total power transmitted and the error rate, will be all considered as objectives.


All the previously listed results will concur to the definition of a new PLC system that will define a dedicated modem for naval PLC. This type of modem is not presently reported in the literature nor available on the market


WG 7 PLC Prototype and experimentation

Partial predicted results
After 4 months (Check Point Phase 3): Meeting and technical report on the simulation and experimental activities.
After 10 months (End WP7): Technical report on the experimental trials aboard Benetti yachts.

Innovation and application fields

All the software and the algorithms developed in the previous WGs will be concur to the definition of a simulator for the naval PLC system. The software that implements the previously defined algorithms will be loaded on a Personal Computer that will drive an arbitrary waveform generator connected to a coupling circuit. This equipment is able to send signals in the transmission channel toward a receiving system constituted by a correspondent coupling circuit and by a data acquisition board connected to another personal computer for the data demodulation.
At this point the experimental phase that will conclude the project will be ready to start. The prototype will be firstly checked at the shipyard on ships provided by “Benetti Yachts” for a test on the efficiency of the system and for producing the last modifications if necessary.
The project will terminate with a test on a naval electric power system in its normal operating conditions during the cruises of ships provided by “Benetti Yachts”.

Patent
In case of a positive conclusion of the experimental tests the developed modem could be patented <<<

Timescale

24 months

National and international background

The transmission of signals to control the electronic and electromechanical devices using powerlines has been exploited since many years by the electric energy supplier companies. For example, the italian company ENEL has been one of the first companies in Europe that have installed a new type of active electrical meters that, using the PLC (Power Line Communication) techniques, are able to provide innovative energy services in anticipation of the liberalization of the electricity supply market.
In recent years, throughout the world there have been large investments of private companies in the production of modems capable of providing broadband signals, by using powerlines in buildings both for private and public use. Many marketed devices are capable to reach average transmission speed of about 30 Mbit/sec in residential low voltage electrical installations. Consequently, the number of companies that are able to provide broadband services both in high populated neighborhoods of cities and in countries located in rural areas, are constantly increasing.
Beyond the significant potential of this technology, some scepticism about the possibility of further increase of the present transmission speeds still exists. These problems concern the increasing demand for "Band" and the real commercial value of the PLC compared with other available technologies (xDSL, Wi-Max, etc.. etc.). Among the technical issues (still under study) that may affect these assessments it could be highlighted the complexity of the transmission channel, which is selective in frequency, time variant and produces stationary and impulsive noise; and the presence of national and international rules that restrict the power of the transmitted signals (electromagnetic compatibility problems).
Nevertheless, the currently reached transmission speeds have increased the possible applications of the PLC that now vary from access to the Internet, to the local networks of computers, or to the communications aboard vehicles.






Nowdays, one of the most promising applications of the PLC technology is its use aboard vehicles.
Indeed, in modern transport systems, trains, planes, cars and ships it is increasing the presence of electronic equipment to proper control the handling of the vehicle (for example to control the stability and braking systems of cars, planes and ships) and even for the entertainment of passengers (e.g. video transmissions on board of planes or ships). Currently, the solution used to control these electronic or electromechanical devices is to install a dedicated cable for each of them. In this way there are dozens of cables of hundreds of meters length, located on board of these vehicles. Consequently, the complexity in wiring these heavy and cumbersome cables has become a major problem in design of these vehicles in order to reserve most possible space for passengers.
The use of powerlines to transmit data could thus eliminating this problem, since it would remove all cables for command and control currently used with enormous advantages in terms of simplification of the wiring cables, and save space and weight.
Since all the PLC systems exploit the electrical cables as a communication channel, the issues that their realization meets in different types of electrical installations are similar and they are usually related to the following topics:
1. Identification of circuits capable to couple, in the most efficient way, the signals to be transmitted to the transmission channel;

2. Identification of techniques for the reduction of electromagnetic fields in the surrounding environment;

3. Estimation of changes in the transmission channel in order to have the maximum possible data transfer speed;
<br />4. Classification of noise in the channel;

5. Optimization of bit-loading algorithms.

Each of these issues can be associated with one aspect of a PLC system that requires specific skills and dedicated techniques that usually are deeply studied by working groups that have diversified knowledge (circuit theory, identification and classification of the signals, electromagnetic compatibility, etc.). For each topic there are specific issues on which the various researchers are debating in order to increase the performance of each components and therefore those of the whole PLC system.

The topic 1 relates to the determination of coupling circuits able to maximize the transfer of power from the transmitter to the receiver according to the well-known principle of impedance adaptation [1] – [3].
There are some problems that complicate the identification of these coupling circuits; in particular: the impedance seen by the transmitter is not known a priori; its value depends on the frequency at which signals are transmitted and on the time in which they are transmitted (that is: the impedance is a parameter that depends on the frequency and time as well as by the specific electrical cable used as channel). Among the most recent examples of adapted coupling circuits, it could be cited those with variable topology. In these circuits the values of certain components are electronically modified on the basis of measured values of voltage or current, in order to follow the changes in time of the transmission channel. So far, however, attempts have been made to meet the changes in time or frequency but not to follow the two things simultaneously.

The topic 2 concerns the electromagnetic compatibility of PLC systems [4] - [6]. The cables of the electrical installations are not shielded and potentially they could be sources of interference with other devices and with the human body, or the cables could be interested by electromagnetic fields coming from the outside. However, the topology of electrical installations in a building is unpredictable and varies from building to building, resulting in an unstandardized system. Then, to estimate the electromagnetic emissions due to PLC signals, the commonly used method is to try to identify the parameters related to the power of the transmitted electrical signals. The intensity of the radiated fields is also in relation to the type of the modulation, resulting in a very complex problem. To the present, the problem is approached following two different lines: the first one is the identification of extremely simplified technique to evaluate the radiated fields, based on measures of field along cables hypothesized as infinitely long conductors (e.g the high-voltage lines in rural areas); the second line concern the possibility to qualitatively assess the possible emissions by using the so-called common mode and differential mode currents.
In the topic 3, the problem of estimation of the time variation of frequency response of the transmission channel is considered [7] - [9]. The strong variation in time of the transmission channel can greatly reduce the efficiency of the system because some frequency bands used for the transmission can be randomly unavailable. Then, it is necessary to be able to move some subcarriers from one frequencial channel to another in order to maintain the same transmission speed. Some consolidated techniques used for this purpose are based on a periodic sending of “pilot” signals (with known characteristics), and their reception on the basis of which it is possible to rebuild the frequency response by the use of interpolation techniques or the minimum mean squared error-base estimation.
Recently, some techniques based on neural networks have been proposed; these methods are able to maximize the transmission speed without the use of the “pilot” signals, but working directly on the transmitted useful signals.
The topic 4 concerns the identification and classification of noise present in electrical installations [10] - [12]. Knowledge of this noise is of fundamental importance to increase the efficiency of the transmission system. Typically the noise existing in a PLC system is non-Gaussian noise and his knowledge and classification can significantly contribute to improve the performance of the system. The various proposed models can be divided into two types: the simplified ones (stationary models) based on a function of probability density like that of Middleton; or the most realistic ones (non-stationary models) which classifies the noise on the basis of its performance in the time domain or on the basis of recent techniques, using the Markov chains or fuzzy-sets
The topic 5 addresses the problem of optimizing the allocation of the amount of bits to be associated with the various carriers that modulate the signal, the so-called "bit-loading" [13] - [15]. Basically there are two types of algorithms for "bit-loading": the most simple (non-adaptive), that tries to minimize the total error, standardizing the power between carriers; and the most complex algorithms, that use more robust encodings, or "adaptive” encodings that are capable to dynamically redistribute the power between the carriers used according to the estimate of the channel itself. A line of investigation in this area is to find a reasonable compromise between the complexity of calculating that reduces the overall transmission speed and the efficiency of the transmission system.
The scientific community working in this field meets in a conference specifically devoted to these issues called International Symposium on PowerLine Communications (ISPLC). Due to the growing interest of the international researchers on this topic, from 2005 the IEEE has established a Technical Committee on PLC and became official sponsor and initiator of the conference itself.
The applications of PLC systems aboard of vehicles have been investigated only in recent years. The most studied vehicle for the application of PLC technology has been the car [16] - [17], and some specific patents [18] - [19] have been produced, confirming the significant industrial interest in this area.
Unfortunately, every type of vehicle has an electrical installation and supply with different characteristics depending on the different requirements of the vehicle itself. Although the general issues listed above are common to all the PLC applications, it is necessary to adapt them to the particular type of electrical system under test and then revised it depending on the type of vehicle.
Concerning the ship, its electrical installation on board is characterized by the fact that it is an “insulated” system. An insulated system is one that is totally electrically insulated from earth (ship's hull). On the contrary, an earthed system (e.g. the electrical installations in buildings) has the supply neutral point connected to earth. However, the on board electrical system transmits large amounts of energy with low voltage for security reasons (to avoid accidental contact with passengers), and it has different electromechanical devices (for example, the propellers), that can be sources of electromagnetic interferences and noise typical in naval applications.
In the specific field of PLC applied to naval systems, very few results have been published so far [20] – [22]. Furthermore, such publications discuss only some measurements on board of certain vessels (cruise ships, military ships and freight), while completely lacking theoretical studies or well-structured experimental tests to obtain an optimized solution in nautical environment. However, some of the authors of those articles are employees of shipping companies, confirming the real interest of the marine industry in this research activity.
It can be state that the PLC technology is extremely innovative and it could contribute for significant improvements in ship building.


[1] A simple line coupler with adaptive impedance matching for Power line Communication, W. Choi, C. Park , ISPLC 2007
[2] A versatile low power PowerLine FSK transceiver, R. Cappelletti, A Baschirotto, IEEE Custom integrated circuits Conference, 2000
[3] ADAPT: mixed-signal ASIC for Impedance adaptation in PowerLine Communications using fuzzy logic, F. Munoz, R.G. Carvajal, A. Torralba, L.G. Freanquelo, Proceedings of the 25th IEEE Conference IECON’99
[4] Derivation of the extrapolation factor for PLC radiation measurements M. H. Hirsch, M. Heina, ISPLC 2007
[5] Common mode Current and radiations mechanisms in PLC networks P. Favre, C. Candolfi, P. Kraehenbuehl, M. Schneider, M. Rubinstein, A. Vukicevic, ISPLC 2007
[6] The Correlation between Radiated Emissions and Power Line Network Components on Indoor Power Line Communications, M. Ishihara, D. Umehara, Y. Morihiro, ISPLC 2007
[7] Blind Channel Estimation for Power-line Communications by a Kohonen Neural Network, M. Tucci, M. Raugi, A. Musolino, S. Barmada , ISPLC 2007
[8]Y. Li, L. J. Cimini and N. R. Sollenberger, “Robust Channel Estimation for OFDM Systems with Rapid Dispersive Fading Channels,” IEEE Trans. on Communications, Vol. 46, No. 7, July 1998, pp. 902¬915.
[9]M. Hsieh and C. Wei, “Channel Estimation for OFDM Systems Based on Comb-Type Pilot Arrangement in Frequency Selective Fading Channels,” IEEE Trans. on Consumer Electronics, Vol. 44, No. 1, Feb. 1998, pp. 217-225.
[10] A mathematical model of noise in NarrowBand PowerLine Communication Systems, M. Katayama, T. Yamazato, H. Okada, IEEE J. in Selected Areas in Communications, July 2006, pp 1267-1277
[11] M. Zimmermann, K. Dostert, “Analysis and modeling of impulsive noise in broad-band powerline communications”, Electromagnetic Compatibility, IEEE Trans. on Vol. 44, Issue 1, Feb. 2002 Page(s):249 – 258
[12] N. Suljanovic, A. Mujcic, M. Zajc, J.F. Tasic, “Computation of highfrequency and time characteristics of corona noise on HV power line”, IEEE Trans. on Power Delivery, Vol. 20, No. 1, Jan. 2005 Page(s): 71 – 79
[13] Bit-Transport Capability of Broadband Multicarrier Power Line Channels constrained by radiated Emission, M. D’Amore, M. Sarto, E. Baccarelli M. Biagi, ISPLC 2007
[14] S. Morosi, D. Marabissi, E. Del Re, R. Fantacci and N. Del Santo, “A rate adaptive bit-loading algorithm for in-building power-line communications based on DMT-modulated systems,” IEEE Trans. on Power Delivery, vol. 21, pp. 1892-1897, Oct. 2006.
[15] B. S. Krongold, K. Ramchandran and D. L. Jones, “Computationally effi-cient optimal power allocation algorithms for multicarrier communication systems,” IEEE Trans. on Comm., vol. 48, pp. 23-27, Jan. 2000.
[16] Performances of the HomePlug PHY layer in the context of in-vehicle powerline communications V. Degardin; M. Lienard; P. Degauque; P. Laly, ISPLC 2007
[17] Tutorial about the implementation of a vehicular high speed communication system T Huck, J Schirmer, T Hogenmuller, K Dostert, ISPLC 2005
[18] Supply line structure for transmitting information between motor-vehicle components T Enders, R Hugel, J Schirmer, F Stiegler, 2003 freepatentsonline.com
[19] Broadband data services over vehicle power lines -
A Whelan, 2005 freepatentsonline.com
[20] Characteristics of Power-Line Channels in Cargo Ships S. Tsuzuki, M. Yoshida, Y. Yamada, H. Kawasaki, K. Murai, K. Matsuyama, M. Suzuki.
[21] Powerline communication over special systems E Liu, Y Gao, G Samdani, O Mukhtar, T Korhonen –ISPLC 2005
[22] Point to Point Multi-media Transmission for Marine Application, J.Yazdani, M.Scott, B. Honary, ISPLC 2002 <<<