JP2007019669A - Modem for power-line communication, user-system plc modem, and access-system plc modem - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a modem for power-line communication, capable of avoiding deterioration in lowest reception sensitivity due to leakage in its control signal into a data reception band for a system, which allows different kinds of PLC networks to coexist in the interior by using a common control signal. <P>SOLUTION: The modem for power-line communication is a modem for power-line communication that allows different kinds of PLC networks to coexist, by making them mutually recognize their presence using control signals, and is equipped with, for example, a data transmitting/receiving circuit (1) which controls half-duplex data transmission and reception that utilize a power line by using a transmission acknowledgement signal, and a control signal generating circuit (5) and a switch (7) that output the control signals, while data transmission is permitted with the transmission acknowledgement signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power line communication modem that performs data communication using a power line indoors, and more particularly to a power line communication modem that can coexist with different types of PLC (Power Line Communication) networks indoors. It is.

  There are two types of PLC networks, for example, "access PLC network" for wide area access (Internet access) and "home PLC network" for communication between devices in the user's home. To do. However, since the PLC networks communicate using the same transmission medium (power line) and frequency band, if they communicate simultaneously, they may interfere with each other and normal communication may be hindered.

  On the other hand, a technique for allowing the access PLC network and the home PLC network to coexist is proposed, for example, in Non-Patent Document 1 described below by ETSI (European Telecommunications Standards Institute). In this document, a method of allocating a frequency band to be used fixedly for each PLC network (interference avoidance method by static frequency division) is described. FIG. 8 is a diagram showing an example of a conventional power line communication method, that is, an outline of an interference avoidance method using static frequency division.

  Furthermore, in Non-Patent Document 1 below, when communication is performed only with one of the PLC networks, higher-speed communication is realized using the entire frequency band, and then other communication is performed using a common control signal. Describes a method (communication avoidance method using dynamic frequency division) in which communication is performed using only a frequency band assigned to the own network in advance when communication via the PLC network is detected. FIG. 9 is a diagram illustrating an example of a conventional power line communication method, that is, an outline of an interference avoidance method using dynamic frequency division.

ETSI TS 101 867 V1.1.1 (2000-11)

  In the above “interference avoidance method by dynamic frequency division”, a control signal (corresponding to the above common control signal) for coexisting different types of PLC networks indoors is required (see FIG. 9), and accordingly, the communication band It is necessary to provide a specific band for the control signal therein. However, in a system in which the control signal and the data signal are transmitted and received in different frequency bands, when the power line communication modem transmits the control signal regardless of the reception period of the data signal of the own device, for example, There is a problem that the control signal leaks into the data reception band, which degrades the minimum reception sensitivity of the device itself, and further narrows the reach of communication.

  The present invention has been made in view of the above, and in a system for coexisting different types of PLC networks indoors using a control signal that is transmitted and received by providing a dedicated band in the communication band, the control signal of the device itself An object of the present invention is to obtain a power line communication modem capable of avoiding the deterioration of the minimum reception sensitivity caused by leaking into the data reception band.

  In order to solve the above-described problems and achieve the object, a power line communication modem according to the present invention operates in a power line communication system provided with a specific band dedicated to a control signal, and uses the control signal to mutually exist. Is a power line communication modem that coexists with different PLC networks, for example, using a transmission permission signal, data transmission / reception control means for controlling half-duplex data transmission / reception using a power line, and Control signal output means for outputting the control signal during a period in which data transmission is permitted by the transmission permission signal.

  According to the present invention, the control signal is not transmitted when the data signal is received, and the control signal is not leaked into the data reception band, so that the deterioration of the minimum reception sensitivity can be avoided, and as a result There is an effect that it is possible to maintain the communication reach when not affected by out-of-band leakage power due to the control signal.

  Embodiments of a power line communication modem according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  In the present embodiment, “in-home PLC network” for data communication within a user's home (between homes, buildings, factories, stores, etc.) and wide area access (outside home data communication) The target "access PLC network" assumes a mixed power line communication system. In this power line communication system, the in-home PLC modem that constitutes the in-home PLC network and the access PLC that constitutes the access PLC network A technique for coexisting modems on a power line and a technique for coexisting home PLC modems constituting different home PLC networks on a power line will be described.

  1-1 is a diagram illustrating a configuration example of an indoor access PLC network, and FIG. 1-2 is a diagram illustrating a configuration example of a home PLC network. The indoor access-type PLC network shown in FIG. 1-1 shows a case where an apartment house is assumed as an example. For example, an access-type PLC modem (base unit) 101 and a single or plural existing in each house. Access system PLC modem (slave unit) 102. In addition, the in-home PLC network shown in FIG. 1-2 represents a network in each house (home) in the apartment house shown in FIG. 1-1. For example, an electric product (personal computer) on which the in-home PLC modem 103 is mounted. , Telephones, televisions, and other home appliances that require power from an outlet).

  In addition, as shown in Fig. 1-2, the above-mentioned electrical products are premised on the installation of a home PLC PLC 103, and some electrical products such as personal computers (including all electrical products) Is equipped with an access PLC modem 102 in addition to the in-home PLC modem 103 and is compatible with both networks. In addition, there may be an electric product equipped with only the access PLC modem 102.

  Here, as an example, a process for making the in-home PLC network and the access PLC network coexist will be described in detail with reference to the drawings. Here, it is assumed that a home PLC modem and an access PLC modem are mixed indoors (detached house, apartment house, building, etc.).

  FIG. 2 is a diagram showing an example of the internal configuration of the access PLC modem 102 and the home PLC modem 103. Note that when both the access PLC modem 102 and the home PLC modem 103 are meant, they are simply referred to as “PLC modems”. In FIG. 2, this PLC modem includes a data transmission / reception circuit 1 for executing a predetermined transmission process for transmission data and a predetermined reception process for a received signal, BPFs 2 and 3 for limiting a band used for data communication, A switch 4 for switching between receiving and receiving, a control signal generating circuit 5 for generating a control signal for coexisting different types of PLC networks indoors, a BPF 6 for limiting a band used for the control signal, and transmission of the control signal And an ON / OFF switch 7.

  FIG. 3 is a diagram showing the frequency band of the control signal and the frequency band of the data signal, where the vertical axis represents power and the horizontal axis represents frequency. In the present embodiment, on the premise that communication is performed using the band shown in FIG. 3, a specific band dedicated to the control signal (the control signal band shown in the figure) is provided, and the presence of each other is determined using the control signal. By recognizing, for example, the indoor access system PLC modems (101, 102) and the home system PLC modem 103 coexist on the power line.

  First, a problem when the control signal transmission process is performed randomly regardless of the data signal reception process will be described with reference to FIG. For example, assuming that the PLC modem receives data in the order of data D # 1, D # 2, D # 3, and D # 4 as shown in FIG. 4, data D # 1 and D # 4 As shown in FIG. 5, since a sufficient SN ratio (SN ratio> xdB: x is a value sufficient for demodulation) is obtained, the data signal bandwidth is The data can be demodulated with high accuracy. However, when data D # 2 and D # 3 are received, the data signal reception period and the control signal transmission period overlap. As shown in FIG. By leaking into the signal band, a sufficient SN ratio cannot be obtained (SN ratio <xdB), and data cannot be demodulated with high accuracy in the data signal band. Specifically, the control signal is a signal output from the device itself, and generally has a higher signal level than the data signal transmitted from the communication partner via the power line, and therefore is received in the data signal band. The data signal cannot be demodulated with high precision due to the influence of out-of-band leakage power of the control signal output from the device itself (deterioration of minimum reception sensitivity). Further, the influence of the out-of-band leakage power is more likely to be received as the signal level of the received data is smaller (the communication reachable range is narrowed).

  Thus, in a power line communication system in which the control signal and the data signal are transmitted and received in different frequency bands, when the PLC modem transmits a control signal regardless of the reception period of the data signal of the own device, the control signal is It leaks into the data reception band (the control signal becomes interference of the reception data), which degrades the minimum reception sensitivity of the own device and narrows the communication reachable range.

  Therefore, in this embodiment, control is performed so that the transmission period of the control signal and the reception period of the data signal do not overlap, thereby avoiding interference with the reception data by the control signal. Hereinafter, processing for avoiding interference with a data signal due to a control signal in power line communication will be specifically described with reference to FIGS. 2 and 7.

  In the PLC modem shown in FIG. 2, first, the data transmission / reception circuit 1 controls a half-duplex transmission / reception process, so that a transmission permission signal (1 shown in FIG. 7) becomes “1” at the time of data transmission and “0” at the time of data reception. + Equivalent to TXEN). For example, at the time of data transmission (+ TXEN = 1), the terminals # 1 and # 3 of the switch 4 are connected by the transmission permission signal, and the transmission data output from the data transmission / reception circuit 1 is transmitted through the BPF 3 and the switch 4 as power. Sent on the line. On the other hand, at the time of data reception (+ TXEN = 0: normally reception is set), terminals # 2 and # 3 of switch 4 are connected by a transmission permission signal and received via the power line, switch 4 and BPF2. A signal is input to the data transmission / reception circuit 1. In FIG. 7, when data is received, that is, when + TXEN = 0, data D # 1 to D # 4 are received.

  In the PLC modem according to the present embodiment, when the transmission permission signal is “1” (+ TXEN = 1), the switch 7 is turned on and when the transmission permission signal is “0” (+ TXEN = 0), the switch 7 operates to be in the OFF state. Accordingly, as shown in FIG. 7, the control signal generation circuit 5 outputs a control signal when + TXEN = 1, that is, when the switch 7 is in the ON state. This avoids overlap between the transmission period of the control signal and the reception period of the data signal.

  In the above, as an example, a case has been described where the home PLC network and the access PLC network coexist. However, the present invention is not limited to this. The same applies to the case of coexistence on the power line.

  Thus, in this embodiment, control is performed so that the transmission period of the control signal and the reception period of the data signal do not overlap. That is, a control signal is transmitted only during a period in which data transmission is permitted, for example, using a transmission permission signal used in half-duplex transmission / reception. As a result, the control signal is not transmitted when the data signal is received, and there is no leakage of the control signal into the data reception band (the control signal does not interfere with the received data). As a result, it is possible to maintain the communication range when the control signal is not affected by out-of-band leakage power.

  As described above, the power line communication modem according to the present invention is useful for a power line communication system in which different types of PLC networks coexist indoors.

It is a figure which shows the structural example of an indoor access type | system | group PLC network. It is a figure which shows the structural example of an in-home system PLC network. It is a figure which shows the example of an internal structure of an access type PLC modem and an in-home type PLC modem. It is a figure which shows the frequency band of a control signal, and the frequency band of a data signal. It is a figure which shows the problem at the time of implementing the transmission process of a control signal at random. It is a figure which shows the mode of a demodulation in case the reception period of a data signal and the transmission period of a control signal do not overlap. It is a figure which shows the mode of a demodulation in case the reception period of a data signal and the transmission period of a control signal overlap. It is a figure which shows the process which avoids the interference to the data signal by a control signal. It is a figure which shows an example of the conventional power line communication method. It is a figure which shows an example of the conventional power line communication method.

Explanation of symbols

1 Data transmission / reception circuit 2, 3, 6 BPF (band pass filter)
4,7 switch 5 control signal generation circuit

Claims (4)

It is a power line communication modem that operates in a power line communication system provided with a specific band dedicated to control signals and allows different types of PLC (Power Line Communication) networks to coexist by using the control signals to recognize each other's existence. And
Data transmission / reception control means for controlling transmission / reception of half-duplex data using a power line using a transmission permission signal;
Control signal output means for outputting the control signal during a period in which data transmission is permitted by the transmission permission signal;
A power line communication modem. An access-system PLC modem that exists in an indoor access-system PLC (Power Line Communication) network by operating in a power line communication system with a specific band dedicated to control signals and recognizing its presence using the control signals In-home PLC modem that exists in the home PLC network that coexists on the power line,
Data transmission / reception control means for controlling transmission / reception of half-duplex data using a power line using a transmission permission signal;
Control signal output means for outputting the control signal during a period in which data transmission is permitted by the transmission permission signal;
An in-home PLC modem characterized by comprising: Operates in a power line communication system with a specific band dedicated to control signals, and recognizes its presence using the control signals, and power and power in the home PLC modem in the home PLC (Power Line Communication) network An access PLC modem that exists in an indoor access PLC network that coexists on the line,
Data transmission / reception control means for controlling transmission / reception of half-duplex data using a power line using a transmission permission signal;
Control signal output means for outputting the control signal during a period in which data transmission is permitted by the transmission permission signal;
An access PLC modem characterized by comprising: Operates in a power line communication system with a specific band dedicated to control signals, and exists in a specific home PLC network, and recognizes its presence using the control signal, so that other home PLCs (Power Line Communication) An in-home PLC modem that coexists on the power line with an in-home PLC modem in the network,
Data transmission / reception control means for controlling transmission / reception of half-duplex data using a power line using a transmission permission signal;
Control signal output means for outputting the control signal during a period in which data transmission is permitted by the transmission permission signal;
An in-home PLC modem characterized by comprising:

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