WO2011076191A1

WO2011076191A1 - Method for determining notching parameters and plc system

Info

Publication number: WO2011076191A1
Application number: PCT/DE2010/001511
Authority: WO
Inventors: Markus Rindchen
Original assignee: Power Plus Communications Ag
Priority date: 2009-12-23
Filing date: 2010-12-23
Publication date: 2011-06-30
Also published as: DE102010055556A1; EP2517366A1

Abstract

The invention relates to a method for determining notching parameters for a PLC (Powerline Communication) signal, wherein frequency ranges are specifically eliminated in the PLC signal by notching and the notching parameters are selected in such a way that an interference of the PLC signal with a radio signal can be largely prevented. In view of a flexible and automatic adaptability of notching parameters, particularly during the ongoing operation of a PLC system, the method according to the invention is characterized in that the frequency range of the PLC signal is scanned using an external receiver with regard to the presence of a utilizable radio signal and that the notching parameters are determined based on the results of said scanning. The invention also relates to a corresponding PLC system.

Description

METHOD FOR DETERMINING NOTCHING PARAMETERS

AND PLC SYSTEM

The invention relates to a method for determining Notching parameters for a PLC (Power Line Communication) signal, wherein the Notehing targeted frequency ranges are omitted in the PLC signal and wherein the notching parameters are selected such that an interference of the PLC signal is largely avoided with a radio signal. The invention further relates to a corresponding PLC system.

With BPL (Broadband Powerline) communication, data is transmitted via the usual power supply network. It is particularly used in buildings, but can also be used to provide the "last mile," ie, to connect buildings to a communications network, and other services are traditionally used in the frequency domain that BPL (Broadband Powerline) uses for transmission The propagation of the various stations is dependent on a variety of natural mechanisms, among which the most important is that shortwave radiation is reflected at the ionosphere, enabling reception over many thousands of kilometers in good conditions. However, the reflection behavior of the ionosphere is dependent on the time of day, solar radiation and other factors, so that the reception of a transmitter at a certain point is not always given.

To avoid collisions, the frequencies that are used by other radio services are intentionally hidden in the BPL signal. This procedure is called a notehing. The frequency ranges that are excluded and where the BPL signal contains no significant transmit power are called notches. In practice, notches are set manually by an administrator. This represents a considerable effort.

With the manual setting of notches fixed notches are implemented to reduce the effort. However, this circumstance means the loss of potentially usable frequencies. In most cases there are shortwave transmitters

CONFIRMATION COPY Transmission times. Accordingly, the frequencies of shortwave are not always used. Furthermore, it is not always expected to be able to realize a satisfactory reception. This circumstance suggests that the BPL transmit signal will only be adjusted accordingly if in fact a "receivable" or "usable" shortwave transmitter exists in that frequency range.

To simplify the setting of notches, these can be determined automatically. A possible concept for automatically determining the notches is described in DE 603 12 839 12. For the procedure, before the start of the PLC activity, the complete frequency spectrum potentially used by the PLC system is scanned and existing radio sources are detected. Alternatively or additionally, it is described that gaps in the time frame or in the frequency band are used for the detection of radio transmitters. Gaps in the time frame are times without PLC activity; Gaps in the frequency band are unused frequency ranges for PLC communication. In addition, special correlation methods may be used to further improve the detection mechanisms.

A disadvantage of the method described in DE 603 12 839 T2 is that it is only applicable if no PLC activity is present. As a result, the entire PLC system must be switched off or deactivated for detection. Thus, even with this system can not be addressed to changing requirements. Once set notches remain until the next reconfiguration, even if, for example, the reception of shortwave transmitters changes during operation of the PLC system.

The present invention is therefore based on the object, a method of the type mentioned in such a way that on changing boundary conditions, in particular with respect to the protected frequency ranges, can be addressed and that a determination of notching parameters at runtime of the PLC system is made possible , A corresponding PLC system should be specified.

According to the invention the above object is solved by the features of claim 1. According to this, the method in question is characterized in that by means of an external receiver the frequency range of the PLC The signal is scanned for the presence of a usable radio signal and the notching parameters are determined based on the results of the scanning.

With regard to the PLC system, the object indicated above is achieved by the features of claim 7. Accordingly, the PLC system is characterized in that the PLC system has an external receiver, that the PLC system has an evaluation unit for determining notching parameters from the signal detected by the receiver, and that a configuration unit is provided, wherein the Configuration unit based on the results of the evaluation Notching parameters determined and / or adjusted.

In accordance with the invention, it has first been recognized that a phase of inactivity of the PLC system is not necessarily necessary for the detection of any radio signals to be protected. Rather, a flexible response to changing radio signals can be achieved by decoupling the detection of the radio signals and the PLC system itself in some way. In accordance with the invention, it has been recognized that for the detection of the radio signals, the receivability of the radio signals does not always have to be determined directly at the location of the radiation of possibly interfering electromagnetic waves. Rather, it is sufficient if the location of the PLC system determines the presence of radio signals to be protected at "not too great distance." The conditions for the propagation of the radio signals do not change so much at the relevant frequencies in most places of use, that at a not too great distance there is a significant change in reception, and what "not too great distances" means in concrete terms depends on the particular location. In a flat area distances of a few kilometers to a few 10 km are conceivable. In a relatively hilly landscape, it may be necessary to limit the distance between the location of the detection and the PLC system to a few 100 m.

According to the invention an external receiver is used, which scans the frequency range of the PLC signal and determines the presence of possibly interfering radio signals in the frequency range of the PLC signal. Of importance here is whether a "usable" or "receivable" radio signal is given. Such a radio signal is present when it can be received and utilized with a commercially available receiver. Only then must measures be taken to avoid disturbances. Other radio signals do not need to be protected. Should a usable radio signal be detected, notching parameters are determined in such a way that when a notch is set with the determined notching parameters, the PLC signal in the area around the radio signal has no significant transmission power. If the detected radio signal is very close to an already set notch, the notching parameters of the nearby notch can be adjusted so that the newly detected radio signal is covered by the notch. These measures can be achieved in an amazingly simple way that notches can be set automatically and that the existing in the frequency range of the PLC signal radio signals are not disturbed. This ensures the coexistence of the radio signals and the PLC system.

In a particularly preferred embodiment of the system, radio stations are detected by the external receiver. The frequency range used in current PLC systems is shortwave radio stations. In addition to shortwave radio stations, it would also be conceivable to exclude other stations that are used for other radio services and not serve the transmission of radio stations.

When radio signals are detected, frequency and schedules may be taken into account to simplify the evaluation of the usability of the radio signals. As a result, the scanning of the frequency band of the PLC signal can be limited to the frequencies at which reception would be necessary according to the frequency and transmission plan. Inactive stations which, for example, have no transmission times at the respective time of day, can be excluded during the scanning process. This considerably reduces the effort involved in checking the frequencies and the scanning process can be significantly speeded up.

Advantageously, it is decided for the presence of a usable radio signal when a radio signal has a sufficiently large field strength for the reception and processing of the radio signal at a receiver. This may be based on high quality, but commercially available receivers be, as they are usually ^¬ sets by users of the corresponding radio signals. If the radio signal does not have a corresponding minimum field strength, the radio signal is classified as unusable and the notching parameters are not determined. It is also possible to include further boundary conditions in the evaluation of the radio signal. Thus, for example, a radio signal can have sufficient field strength, but is so distorted that it can not be reproduced or processed with any conventional receiver and thus no longer utilizes the radio signal. Such a radio signal could also be qualified as unusable.

If a radio signal has been classified as recoverable in a previous scan, and the scan changes again, the corresponding notching parameters can be adjusted and the radio signal can no longer be excluded from the frequency range of the PLC signal. It is also possible to wait a certain amount of time for the "non-usable barkeep" until the corresponding notching parameters are changed and the frequency range for the PLC signal is released again. In this way, short-term dips in the reception of the radio signal can be intercepted. This further reduces potential interference between the radio signal and the PLC signal.

Preferably, information about the presence of a usable radio signal is determined by an evaluation unit which is connected to the external receiver. The evaluation unit uses information from the external receiver, such as field strength, signal quality and / or distortion. The evaluation unit determines the frequencies that must ultimately not be used by the PLC signal, otherwise a collision would occur with a usable radio signal.

The information determined by the evaluation unit on the presence of a usable radio signal in the frequency range of the PLC signal can be forwarded to a configuration unit that further processes the information. The task of the configuration unit would be to determine the necessary notching parameters or to adjust notching parameters accordingly for already set notches. The most important information of the Notching parameters may include the center frequency, the width and the steepness of the notch. The con- In particular for the adaptation of the notching parameters, the figuration unit can store information about the already set notches and the associated notching parameters or access this information in a suitable manner.

The external receiver, the evaluation unit and the configuration unit can be combined in any way. Thus, for example, the evaluation unit could be implemented directly at or even in the receiver and the information extracted by the evaluation unit could be forwarded to the configuration unit via a network connection. The configuration unit may, for example, be implemented at or in the unit responsible for managing the usable frequency range in the PLC system. Further conceivable combinations are immediately apparent to a person skilled in the art.

The determined and / or changed notching parameters can be forwarded to a network management system (NMS). The NMS can implement the respective notches based on the obtained notching parameters. The NMS can be configured as a central component in the access network and in this way automatically adapt notches in the entire PLC system. This would allow an administered BPL (broadband power) access network to be automatically adjusted. However, the NMS can also make adjustments for smaller network areas. For example, the NMS can manage the PLC network in a single or a few buildings. This could adapt the network segment, in this case the PLC system within the building (s). In this way, the present inventive method and the PLC system according to the invention are particularly universally applicable.

Preferably, the frequency range of the PLC signal is periodically scanned for radio signals. The external receiver can be periodically tuned from the minimum frequency to the maximum frequency of the PLC frequency range (or vice versa) and the usability of any radio signal received at the frequency determined in each case. Alternatively, other techniques can be used to scan several frequencies in parallel. For this purpose, sufficient methods and techniques are known from the prior art. Preferably, the periodic scans after a time interval t new values for the usability of a radio signal and thus data on the usability of a frequency range in the PLC signal (usually a subcarrier of the PLC signal) are present. The distance t should be chosen to be so small that it falls below the standards or statutory times with which the occurrence of radio signals must be responded to. Preferably, the distance t is chosen to be less than 15 seconds.

The central receiver could be located at a central location of the network or a network segment. Sub-distributors of the network or the network segment can be used. To improve the quality of the rating, the external receiver may be located on a building or other exposed point. The more representative the place of installation of the external receiver for the respective environment, the safer an interference between the radio signal and the PLC signal can be excluded. Through skillful combination of the various measures, good reception and shortest possible paths between the units can be realized.

The external receiver may be located at the provider in the access network. In this way, a relatively large area can be covered with a single external receiver. The NMS of the provider can specify for all connected consumers, which notches are to be set by the participants and which frequencies may be used. As a result, the necessary additions to the infrastructure in the PLC system can be reduced to a minimum.

To achieve a higher granularity, which takes into account very local reception differences, an external receiver can also be used for smaller networks or network segments. The size of the segments can be reduced to the extent that an external receiver is used for a single building. In such an application scenario for the method according to the invention and the PLC system according to the invention, the external receiver can then be mounted in or on the building in which the PLC network or network segment is operated. Preferably, the external receiver has a high sensitivity. This can avoid that radio signals may not be detected due to a poor quality of the receiver.

In summary and based on a preferred embodiment of the invention, the problem outlined at the outset is solved by the currently "receivable" transmitters being detected by a central external receiver and this information being forwarded to a network management system which automatically adjusts the notches in the access network From this, the notching parameters can be determined and automatically set in an administered BPL access network, thus making it possible to make better use of existing frequencies while avoiding collisions with other radio services.

The central receiver preferably has good reception characteristics. Shortwave transmitters are scanned and evaluated at a distance t. For transmitters that are high enough to be considered "receivable", the notch parameters are determined and forwarded to the NMS (Network Management System) The NMS implements the notches in the complete BPL access network.

All BPL access network systems operating in the frequency range of 1.6 to 30 MHz can be equipped with the system according to the invention.

With regard to further advantageous embodiments of the device according to the invention, reference is made to avoid repetition to the general part of the specification and to the appended claims.

Finally, it should be expressly understood that the above-described embodiments of the device according to the invention are only for the purpose of discussion of the claimed teaching, but not limit these to the embodiments.

Claims

1 . Method for determining Notching parameters for a PLC (Powerline Communication) signal, wherein the Notehing targeted frequency ranges are omitted in the PLC signal and wherein the notching parameters are chosen such that an interference of the PLC signal with a radio signal largely is avoided

That is, by means of an external receiver, the frequency range of the PLC signal is scanned for the presence of a usable radio signal, and the notching parameters are determined based on the results of the scanning.

2. The method according to claim 1, characterized in that is scanned by means of the external receiver for radio stations in the frequency range of the PLC signal.

3. The method according to claim 1 or 2, characterized in that it is decided for the presence of a usable radio signal when a radio signal has a sufficiently large field strength for the reception and the processing of the radio signal at a receiver.

4. The method according to any one of claims 1 to 3, characterized in that information about the presence of a usable radio signal in the frequency range of the PLC signal is forwarded to a configuration unit and that preferably determined by the configuration unit based on the received information Notching parameters and / or adapted.

5. The method according to claim 4, characterized in that the determined and / or changed notching parameters are forwarded to a network management system (NMS), whereby notches are implemented by the NMS based on the Notching parameters.

6. The method according to any one of claims 1 to 5, characterized in that by means of the external receiver, the frequency range of the PLC signal is scanned at a distance t, wherein the distance t is preferably selected smaller than 15 s.

7. PLC system in which by means of notehing frequency ranges can be faded out, which can collide with radio signals, in particular for carrying out a method according to one of claims 1 to 6,

characterized in that the PLC system comprises an external receiver, that the PLC system has an evaluation unit for determining notching parameters from the signal detected by the receiver and that a configuration unit is provided, wherein the configuration unit based on the results of the evaluation unit Notching parameters are determined and / or adapted.

A PLC system according to claim 7, characterized in that the external receiver is arranged at a central location of a network or a network segment, preferably in a sub-distributor of the network or of the network segment.

9. PLC system according to claim 7, characterized in that the external receiver is arranged in or on a building, wherein the PLC system is operated at least partially in the building.

10. PLC system according to one of claims 7 to 9, characterized in that the external receiver has a high sensitivity.