IL137139A

IL137139A - Method and apparatus for communication over power line

Info

Publication number: IL137139A
Application number: IL137139A
Authority: IL
Original assignee: Polytrax Inf Technology Ag
Priority date: 1999-07-12
Filing date: 2000-07-03
Publication date: 2006-04-10
Also published as: EP1073211A3; NO20003542D0; JP3633857B2; NO20003542L; DE50015167D1; IL137139A0; JP2001060899A; ATE396552T1; EP1073211A2; EP1073211B1

Abstract

Information is transmitted over an electrical mains power supply line (1)and is communicated to and from a server (4) and terminals via a modem (2). Each modem has a memory for the modulation parameters and the carrier frequency data. The contents are determined by a controller (23) coupled to an I/O stage.

Description

Method and apparatus for communication over power line PoIyTrax Information Technology Aktiengesellschaft C. 126211 Method and apparatus for communication over power line Description The invention relates to a method and an apparatus for communication o the lines (powerlines) of the electric power distribution network.

The desire for electronic communication, i.e. for electronic transmission of various information, and data increases steadily. Therefore, their exists an increasing need for suitable transmission media and channels.

One such medium is the electric power distribution network with nearly worldwide installation and easy access for modern people.. The European CENELEC standard EN 50065 provides different frequency bands in .a region of up to 148.5 kHz for information transmission on the low voltage part of this network (in Central Europe: 230V, 50 Hz; in other countries, e.g. 120V, 60 Hz). A conventional system, for data transmission within this standard is disclosed in application note AN 655 of SGS-Thompson company, http://www.st.com. This system comprises a modem for generating and receiving data transmitted by frequency modulation at fixed frequencies of about 131 and 133 kHz.

Fast data transmission for high- definition video signals in real. time or for fast internet access requires data transmission rates in the region of 1 Mbit/s or more. In practice, these transmission rates cannot be realised with required reliability within the above standard for the electric power distribution network with its high noise levels and large signal attenuation.

The inventors have therefore considered frequency ranges above 150 kHz and up to about 30 MHz. There are currently no general standards or rules which determine allowed signal levels specifically for communication on the power distribution network in such higher frequency ranges. A general in- stallation of equipment using these ranges increases the danger that present radio services which have licenses for operatio in the same frequency range will be disturbed.

The frequency range of 0.15 to 30 MHz is presently occu^ pied by a large number of radio services, each being assigned a small portion of the entire range. Operation of electronic equipment which interferes with licensed radio services can be prohibited by the governmental offices for regulation of telecommunication. Since present frequency assignments can only be changed with notice long in advance, considerations ar made for a "conditional release" of frequency ranges which are known to the regulation offices as hardly or not at all used by radio services. This means that the release can be ■ withdrawn as soon as a radio service is disturbed in its fre- quency range.

In this situation, fast electronic communication through the energy distribution network is technically and economically conceivable but the provider of such communication services or the supplier of appropriate systems has to face the risk that his services or systems can be prohibited by regulation offices because they disturb licensed radio services. Wider applications could therefore lead to costly recall actions for the provider and supplier.

It is therefore an object of the invention to provide a method and. an apparatus for fast and efficient communication over the power distribution network.

This object is solved by the method of claim 1 and the apparatus of claim 9. The subclaims relate to preferred embodiments of the invention.

The invention allows optimum use of the resources of a •power distribution network by reprogramming the communication apparatus in accordance with the availability of the network. Therefore, it is unnecessary to replace the apparatus entirely when for example certain frequency ranges are no longer available because they disturb, othe services or are disturbed themselves, or when individual frequency ranges become available because a disturbance has been eliminated or other services feel no longer disturbed. In practice, it is typically a modulation means and/or a demodulation means in the apparatus which is reprogrammed.

Preferably, the reprogramming involves at least one of the following measures: • redefining the position of one or more carrier frequencies, • changing the type of modulation, for example, the modula- tion method, the modulation depth or modulation index, • redefining the amplitude of individual ones or all carrier signals, "" • in a. microprocessor-controlled modulation or demodulation means, exchanging part of or the entire software of the microprocessor, • redefining the frequency response of digital filters in the modulation or demodulation means, • setting a new data transmission rate^ • setting new data transmission directions for individual or all carrier signals, · changing functions of the modulation or demodulation means which influence the use of resources of the power distribution network as a transmission medium, • redefining rights for communication with certain remote terminals which interfere with others due to their location or used carrier frequencies, for example, and • locking or relieving the modulation or demodulation means entirely or for certain time periods.

Detecting the availability of the power distribution network is preferably based on a measurement of the characteristics of one or more of its transmission channels. The measurement and the reprogramming are preferably made with a robust type of modulation hardly affected by disturbances so that reprogramming can be safely carried out also in reaction to interference.

Subclaims 2 and 4 to 6 relate to individual ones of the preferred reprogramming measures set forth above.

The embodiment of claim 3 has the advantage that the re-programming can be made economically without separating the apparatus from the power distribution network, in particular without sending it to the manufacturer or service. Preferably, the apparatus detects a change in the availability of the resources of the power distribution network through the reception of a command signal in accordance with claim 7. Thus, transmission of the command signal from e.g. a network provider initiates remote programming of the apparatus. A preferred embodiment of the apparatus is set forth in claim 10.

Preferred embodiments of the invention will now be ex-plained with reference to the drawings. The single figure shows schematically a circuit for using a power distribution network for data transmission.

As shown in the figure, terminals 3, 3' and a network provider 4 (server) are each coupled to a power distribution network 1. The coupling is effected by a respective modem 2, 2', 2" and an interface 5, 5', 5".

The power distribution network 1 includes the low voltage in- or out-house network or. the medium voltage network. It is used for transmission of data in the form of modulated signals between terminals 3, 3' and the provider 4. Each interface 5, 5V, 5" serves for separating the respective modem 2, 2 ' , 2" from the power distribution network 1 so that the power supply voltages on the network 1 do substantially not reach the modem 2, 2', 2" while the modulated signals used for data transmission can pass.

Each modem 2, 2', 2" comprises a modulation and demodulation circuit 21 for conversion between on the one hand digital data from and to the respective terminal. 3, 31 or provider 4 and on the other hand the modulated signals from and to the power distribution network 1 via the respective interface 5, 5', 5". The modulated signals reside within one or more frequency bands in the region of 0.15 to 30 MHz. Each frequency band includes the frequencies of one or more carrier signals (carrier frequencies) which are modulated with said digital data in the modulation and demodulation circuit 21. The type of modulation is DMT-OFDM (discrete multitone-orthogonal frequency division multiplex) or alternatively multi-carrier-CDMA (multi-carrier code division multiple access) .

Each modem 2, 2', 2" is adapted so that the used fre-quency bands can be changed at any time and as often as desired. This allows ready adaptation to changing frequency assignments. To this end, the modem comprises a rewritable memory 22 realised as an EEPROM and a control unit 23 in the form of a microprocessor. The functions of the modem 2 , 2', 2" described herein can, however, also be realised by means of a DSP (digital signal processor) or an ASIC (application specific integrated circuit). The memory 22 holds software data which determine the carrier frequencies used by the modulation and demodulation circuit 21. The control unit 23 is connected to the memory 22 as well as to an input/output terminal 24 for the digital data of the modulation and demodulation circuit 21. Thereby, the control unit 23 can receive a command signal included in the digital data. The command signal sets the modem into, a programming mode wherein it instructs the control unit 33 to change the definition of carrier frequencies held in the memory 22 so that thereafter certain carrier frequencies are no longer used or other carrier frequencies are newly used. Hence, the modem 2 can be remote programmed from the associated terminal 3 or from the provider 4 by means of the command signal. The modem 2 can thus be reprogrammed in situ without having to be sent to the manufacturer or service.

Accordingly, the modem 2, 2', 2" detects by reception of the command signal that the availability of the power distri-bution network 1 for the modulated signals and their individ- ual characteristics such as carrier frequencies, type of modulations or signal amplitudes used so far has changed.

The control unit 23 responds to the command signal only when the latter contains a unique address individually desig-nating the respective modem 2, 2', 2". Thus, each individual modem can be reprogrammed o several modems can be repro-grammed as a group. Preferably, the content of the memory 32 can be read out via the control unit 23 to the provider 4 or the associated terminal 3 so that it can be reviewed and a reprogramming needs only be conducted if, necessary.

The command signal can be formed by the provider 4 with or without previously getting permission from the user of the associated terminal 3, 3'. Without permission of the user, this can be done for example at each access of the user to a system such as an internet connection made available by the provider 4.

In modification of the above described embodiment, re-programming of the modem.2, 2', 2" can also be effected through an analogue telephone line, an ISDN connection, a connection to a cable TV network, a radio link (e.g. GSM, DECT, W-CDMA, CDMA, Bluetooth), via an infrared link, a computer interface (for example a serial or parallel interface, a USB or PCMCIA connector) , through a digital data input device (for example a CD, DVD or floppy disk drive), by re-placement of the digital memory 22 which can then be realised as an EPROM, or through any other digital bus.

The operation of the modem will now be explained in connection with different practical examples: If the provider 4 is an internet service provider, he can recognise for example at each internet access of the terminal 3 that the access is conducted through its own modem 2" and the power distribution network from the modem 2. Then, the version of the software in the memory 22 is polled by means of command signals to: the control unit 23 and if neces-sary, the software is updated automatically or upon agreement by the user at the terminal 3.

In a different example, the provider 4 distributes updated software for example on a 3.5" floppy disk to his customers when the availability of resources of the power distribution network 1 for data transmission has changed. The terminal 3 is a personal computer connected to the modem 2 by the user. The user reprograms the modem 2 with the floppy disk and the personal computer.

In another example, the user changes his contract with the provider 4. Accordingly, his modem 2 is' reprogrammed to a higher data transmission speed, to extended access rights for data transmission services, to a larger number of video channels selectable and receivable via the transmission medium of the power distribution network, or to a different selection of obtainable services such as games, movies, etc.

In another practical example, a new airport is constructed in the area of the terminals 3, 3'. For undisturbed operation of the airport, the modems 2, 2' of the area are reprogrammed from remote so as to release individual frequency ranges used so far so that they are no longer used by the modems 2, 2' whereas other frequency ranges are newly allocated to them.

In a still further example, the signal/noise ratio for information transmission on the low voltage network is improved by purposeful measures such as shielding and filtering of disturbances originating from individual loads of the network, whereupon all modems 2, 2', 2" of the network are switched to a faster type of modulation, e.g. from 8 QAM to 64 QAM.

Eventually, in an embodiment, the control unit 23 of the modem 2 determines the transmission quality based on the error rate in the data transmission over the power distribution network 1 or based on measurement of other characteristics of the lines of the power distribution network, and stores information on the transmission quality in the memory 22. For example, characteristics such as an attenuation of the network or lines in the frequency spectrum of noise signals can be measured and stored as a disturbance protocol. The stored information is read out from time to time by the provider 4 and is used to reprogram the modem 2 so that the transmission quality is improved. This is done by sending the command signal to the modem 2 to e.g. deactivate frequency regions where interference occurs and activate new frequency regions having low interference. Thus, the control unit 23 of the modem 2 recognises only based on the command signal from the provider 4 that reprogramming is necessary. Preferably, however, the control unit 23 recognises itself that transmission errors become more frequent or interference gets even out of control and initiates the reprogramming itself, based on the disturbance protocol. Then, the control unit 23 may conduct the entire reprogramming on its own or may request the above-described command signal from the provider to do reprogramming as instructed by the provider 4.

Claims

- 9 - 137139/2 CLAIMS:

1. A method for transmission of information by means of a communication apparatus via a power distribution network, comprising the following steps: defining a carrier signal and a type of modulation, modulating the defined carrier signal with the information to be transmitted, in accordance with the defined type of modulation, transmitting the modulated signal over the power distribution network, detecting the availability of the power distribution network for a modulated signal, reprogramming the apparatus in accordance with the detected availability, and continuing said modulation and transmission steps with the reprogrammed apparatus; wherein said reprogramming involves a change of the type of modulation with a reduction of the information transmission rate when a reduction of the signal/noise ratio has previously been detected, and with increasing information transmission rate when an increasing signal/noise ratio has previously been detected.

2. A method according to claim 1 , wherein the reprogramming of the apparatus is made in situ.

3. A method according to claim 1 , wherein instead - 10 - 137139/2 or in addition to said modulation step a step for demodulation of the transmitted, modulated carrier signal is carried out after said transmission step.

4. An apparatus for transmission of in ormation over a power distribution network, comprising: means for defining a carrier signal and a type of modulation, means for modulating the defined carrier signal with the information to be transmitted, in accordance with the defined type of modulation, and for transmitting the modulated carrier signal over the power distribution network, characterised by means for detecting whether the power distribution network is available for a modulated carrier signal and for reprogramming the apparatus when a change of the availability is detected so that the transmission is continued in accordance with the detected availability with the reprogrammed apparatus; wherein the means for detecting and reprogramming involves a change of the type of modulation with a reduction of the information transmission rate when a reduction of the signal/noise ratio has previously been detected, and with increasing information transmission rate when an increasing signal/noise ratio has previously been detected. - 11 - 137139/2

5. An apparatus according to claim , wherein the modulating means is adapted, instead or in addition to said modulation, also for demodulation of a transmitted, modulated carrier signal in accordance with said defined type of modulation. For the Applicants, REINHOLD COHN AMD PARTNERS