JP2008182558A - Power line communication device - Google Patents

Abstract

A power line communication apparatus capable of easily stopping transmission of a power line communication signal without turning off a power supply.
A power line communication device that is connected to a terminal device that performs power line communication and performs communication using the power line as a signal transmission path. A link state detection unit for detecting a link state with the terminal device, and when the link state detection unit detects that the link with the terminal device is down, Signal stopping means for stopping signal transmission.
[Selection] Figure 1

Description

  The present invention relates to a power line communication apparatus.

  Power line communication (PLC) is a technique for performing communication using a power line as a signal transmission path, and is described in Patent Document 1, for example.

  In this power line communication, high-speed communication is performed using an existing power line in the house, and a power line communication device (PLC modem. Hereinafter, simply referred to as “modem”) is connected to a power outlet without additional wiring for communication. ) Can be used to form a home network.

  By the way, in power line communication, even for modems that are only connected to the power line but are not actually communicating with data exchange, the number of modems connected to the power line is inquired about whether communication is necessary. As the number increases, the expected value of the maximum communication speed decreases. When a modem is activated but a terminal device such as a personal computer connected to the modem is shut down, output of unnecessary communication signals is stopped to increase communication speed and improve the efficiency of the entire network. Can be made.

  Also, modems used for power line communication generally do not have a switch for turning on and off the output from the modem because of the design philosophy of keeping it usable in terms of the function as a communication device. In order to turn off the modem output, it is necessary to turn off the power. However, depending on the installation location of the modem, the power may not be turned off easily. Therefore, if it is necessary to stop the power line communication for some reason and the power cannot be easily turned off, either disconnect the Ethernet cable connected to the modem, or It would be convenient if power line communication could be stopped simply by shutting down a terminal device such as a personal computer connected to the modem.

  Furthermore, it is conceivable that the modem is built in and used in a router having an interface for a different communication method such as Ethernet or wireless LAN. In this case, in order to maintain the function of the wireless LAN or the like, There are cases where you want to turn off only the power line communication without turning it off. At that time, it is convenient if the transmission of the power line communication signal from the modem can be stopped by the link state of the power line communication.

Japanese Patent Laid-Open No. 10-145265

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power line communication apparatus that can easily stop transmission of a power line communication signal without turning off the power.

A power line communication apparatus according to a first aspect of the present invention is a power line communication apparatus that is connected to a terminal apparatus that performs power line communication and performs communication using the power line as a signal transmission path.
Link state detecting means for detecting a link state with the terminal device;
Signal stop means for stopping transmission of a signal for power line communication to the power line when it is detected by the link state detection means that the link with the terminal device is down;
It is characterized by having.

  In the power line communication device according to the first aspect of the present invention, the link between the power line communication device (modem) and the terminal device such as a personal computer is detected by the link state detecting means for detecting the link state between the power line communication device (modem) and the terminal device. When it is detected, the signal stop means stops the transmission of the signal for power line communication to the power line. Therefore, when the power line communication needs to be stopped for some reason and the power cannot be easily turned off, the cable connecting the modem and the terminal device is disconnected or connected to the modem. By simply shutting down a terminal device such as a personal computer and bringing down the link between the terminal device and the modem, the power line communication can be easily stopped without turning off the power of the modem.

  Also, when the modem is activated but the terminal device such as a personal computer connected to the modem is shut down, the output of unnecessary communication signals is stopped to increase the communication speed and Efficiency can be improved.

Furthermore, in the case of a modem used in a router having an interface for different communication methods such as Ethernet and wireless LAN, the power supply of the entire router is not turned off by bringing down the link between the modem and the terminal device. In addition, only power line communication can be turned off. Thereby, functions such as the wireless LAN can be maintained while only power line communication is turned off.
Preferably, the apparatus further comprises signal restarting means for restarting transmission of a signal for power line communication to the power line when the link state detecting means detects that the link with the terminal device is up. . In this case, the stopped power line communication can be restarted by the signal restarting means when the link state detecting means detects that the link with the terminal device is up.

A power line communication apparatus according to a second aspect of the present invention is a power line communication apparatus used in a power line communication network including a plurality of power line communication apparatuses that perform communication using a power line as a signal transmission path,
A PLC transmission / reception unit capable of transmitting / receiving a communication control signal for controlling communication in the network;
Control signal stopping means for stopping transmission of a communication control signal to the power line when there is no other power line communication device as a communication partner on the power line;
It is characterized by having.

In the power line communication device according to the second aspect of the present invention, when there is no other modem as a communication partner on the power line, the transmission of the communication control signal to the power line is stopped by the control signal stop unit. The standby power of the modem can be reduced. Further, unnecessary electric field radiation can be suppressed, and the influence on wireless communication in an interference state can be reduced.
It is preferable to further include a control signal restarting unit that restarts transmission of a communication control signal to the power line when a power line communication device as a communication partner appears on the power line. In this case, the control signal whose transmission has been stopped can be restarted by the control signal restarting means when a power line communication device serving as a communication partner appears on the power line.

  A timer means for measuring the time of the non-link state with another power line communication device, the control signal stop means, when the time of the non-link state after activation of the power line communication device exceeds a predetermined time, It is preferable that the transmission of the communication control signal to the power line is stopped. In this case, the timer means measures the time of the non-link state with the other modem, and another modem as a communication partner is found on the power line within a predetermined time (for example, 60 seconds) after the modem is activated. When there is not, transmission of the communication control signal to the power line can be automatically stopped.

  While the transmission of the communication control signal is stopped by the control signal stop means, the power line communication is resumed when a communication control signal is received from another power line communication device. preferable. In this case, power line communication can be resumed when necessary.

  According to the power line communication of the present invention, it is possible to easily stop the transmission of the power line communication signal without turning off the power.

  Hereinafter, embodiments of a power line communication device of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a power line communication network system in which a plurality of power line communication devices are arranged.

  The optical fiber 7 connected to the external Internet is connected to the photoelectric conversion device 6. A signal line S1 is connected to the photoelectric conversion device 6, and for example, broadband routers 50, 50 provided in each of the homes A, B, C of the housing complex as an ADSL line on the WAN side. , ... are connected. In some cases, the optical fiber 7 is directly connected to the broadband routers 50, 50,... Provided in the homes A, B, C of the apartment house without using the photoelectric conversion device 6.

  The broadband router 50 is connected to parent modems (power line communication devices serving as parent devices) a1, b1, and c1 through a signal line S2 on the LAN side. The transformer 5 connects a medium voltage distribution line 8 that distributes a medium voltage (for example, 6 kV) of a three-phase alternating current to the primary side, and connects a power line 9 to the secondary side to reduce the medium voltage. Convert to voltage (for example, 100V or 200V). The power line 9 is connected to in-home power lines 9a, 9b, 9c in each of the homes A, B, C via a distribution board (not shown).

  In each home, power outlets 10, 10,... Are appropriately provided on the home power lines 9 a, 9 b, 9 c, and the parent modems a 1, b 1, c 1 and the personal computer 4 that is a terminal device are connected to the power outlet 10. Child modems a3, b3, and c3 to which child modems (power line communication devices serving as child devices) a2, b2, and c2 and a refrigerator 11 as information home appliances are connected are connected.

  The power line communication networks (LAN) in the homes A, B, and C are operated as separate network groups. However, the in-home power lines 9a, 9b, and 9c used as signal transmission paths in the power line communication network groups in the homes A, B, and C are connected to the common power line 9.

  FIG. 2 is a functional block diagram of the modem. Since the basic function of the modem is common to the parent modem and the child modem, the parent modem P will be described below as a representative.

  The modem P can be connected to a power outlet 10 provided in the house via a power plug 22 provided at the tip of a power cord 21 extending from a casing (not shown) constituting the modem P. It is configured. A power connector to which one end of the power cord 21 (the end opposite to the power plug 22) is connected and an Ethernet connector 61 to which the Ethernet cable 60 is connected are disposed on the side surface of the casing.

  The power cord 21 is connected to the power circuit 23 and the PLC transmission / reception unit 24 via a coupler 30 that superimposes the PLC signal on the power line in the casing. The PLC transmitting / receiving unit 24 performs processing such as modulation / demodulation of a signal for PLC communication transmitted / received via a power line. The modem P includes a digital signal processing unit 25 that controls the PLC transmission / reception unit 24 and processes transmission / reception data. Further, an Ethernet transmission / reception unit 32 that communicates with the terminal device is connected to the digital signal processing unit 25, and the Ethernet transmission / reception unit 32 is connected to an Ethernet connector 61 to which the Ethernet cable 60 can be connected. ing.

  The digital signal processing unit 25 includes an ether link detection unit 25a for detecting a link state with a terminal device such as a personal computer, a PLC link detection unit 25b for detecting a link state with another modem, both detection units 25a, A signal stop unit 25c for stopping transmission of a signal for power line communication to the power line, and a signal resumption unit 25e for restarting transmission of the signal for power line communication to the power line when any of the link downs is detected. Is provided.

  The modem P performs communication by a frequency multiplexing method using a plurality of carrier waves (multicarrier) in a predetermined frequency band for power line communication. Specifically, the modem P performs modulation using a modulation method called orthogonal frequency division multiplexing (OFDM).

  For this reason, the PLC transmission / reception unit 24 has a quadrature amplitude modulation (QAM) function, and distributes and allocates data to be transmitted to each of a plurality of carriers. Based on the allocated data, the PLC transmission / reception unit 24 has a function of quadrature amplitude modulation (QAM). Modulate amplitude (power) and phase. In the present embodiment, 2 to 30 MHz is used as a frequency band for power line communication.

  In addition, the digital signal processing unit 25 can give the control signal to the PLC transmission / reception unit 24 to appropriately increase or decrease the amplitude (power) of the carrier. This increase / decrease can be performed uniformly for all carriers, or can be performed for some carriers.

  The modem of the present invention is configured to be able to stop and restart transmission of power line communication signals in accordance with the link state on the Ethernet side. That is, the modem of the present invention includes a link state detecting means (ether link detecting means) 25a for detecting a link state with a terminal device such as a personal computer, and a signal stopping means 25c for stopping transmission of a signal for power line communication to the power line. When the link state detection unit 25a detects that the link with the terminal device is down, the signal stop unit 25c uses the signal for power line communication to the power line. Is stopped. Therefore, if it is necessary to stop power line communication for some reason and the power cannot be easily turned off, the Ethernet cable connected to the modem is disconnected or connected to the modem. By simply shutting down a terminal device such as a personal computer and bringing down the link between the terminal device and the modem, the power line communication can be easily stopped without turning off the power of the modem. The stopped power line communication can be restarted by the signal restarting means 25e when the link state detecting means 25a detects that the link with the terminal device is up.

  Further, the modem of the present invention may be provided with a control signal stop means for stopping transmission of a communication control signal to the power line when there is no other modem as a communication partner on the power line. By stopping transmission of the communication control signal from the modem, the standby power of the modem can be reduced. Further, unnecessary electric field radiation can be suppressed, and the influence on wireless communication in an interference state can be reduced. The control signal whose transmission has been stopped can be restarted by the signal restarting means 25e when a modem as a communication partner appears on the power line.

  By realizing both the configuration that stops signal transmission for power line communication according to the link state on the Ethernet side of the modem and the configuration that stops transmission of communication control signals when there is no communication partner on the power line, The effect of suppressing unnecessary electric field radiation is high, and the degree of freedom of the means to be executed when the user wants to stop power line communication without stopping the power supply of a device with a built-in modem, for example, is increased.

  FIG. 3 is a diagram for explaining an example of the use of a modem. Various types of modems are connected to a power line 19 indicated by a thick line. In this example, when the Ethernet cable 35 connecting the personal computer 34 and the modem P1 is pulled out from the modem P1 or the personal computer 34 is shut down, the link is periodically made to confirm the link state between the modem P1 and the personal computer 34. There is no response (signal) from the personal computer 34 to the signal transmitted from the modem P1 to the personal computer 34. The ether link detection means 25a of the digital signal processing section 25 detects that there is no response signal within a predetermined time, and then there is no response from the personal computer 34 by the timer means 25d included in the digital signal processing section 25 of the modem P1. When the time is counted and this time exceeds a predetermined time, the signal stop means 25c of the digital signal processing unit 25 sends a control signal to the PLC transmission / reception unit 24, assuming that the link between the modem P1 and the personal computer 34 is down. The transmission of the signal for power line communication from the PLC transmitting / receiving unit 24 is stopped.

  In the case of the information home appliance 41 having a built-in modem P2, for example, a refrigerator, the power line communication signal can be stopped when the modem P2 is turned off. However, the power supply is also stopped. Therefore, it can no longer function as a refrigerator. In such a case, the Ethernet link switch 42 is provided in the wiring between the modem P2 and the Ethernet interface 43, and the Ethernet link can be brought down by operating the Ethernet link switch 42. As in the case of the modem P1, the digital signal processing unit 25 of the modem P2 detects that the Ethernet side link of the modem P2 is down, and transmits the power line communication signal from the PLC transmission / reception unit 24. Stop.

  In the case of the router 53 having the built-in modem P3 and the wired LAN interface 51 and the wireless LAN interface 52, other modems serving as communication partners on the power line are connected to the digital signal processing unit 25 of the modem P3. By providing the signal stop unit 25c, which is a control signal stop unit that stops transmission of the communication control signal to the power line when it does not exist, the power of the router 53 can be changed according to the link state of the power line communication without turning off the power. PLC communication can be stopped. For example, the digital signal processing unit 25 of the modem P3 is provided with a PLC link detection unit 25b for detecting a link state with another modem, and a timer unit 25d for measuring the time of a non-link state with another modem, The signal stop means 25c is configured to stop transmission of a communication control signal to the power line 19 when the non-link state time after the activation of the modem P3 exceeds a predetermined time (for example, 60 seconds). be able to. Thereby, the timer means 25c measures the time of the non-link state with the other modem, and automatically when no other modem as a communication partner is found on the power line within a predetermined time after the modem P3 is activated. Thus, transmission of the communication control signal to the power line 19 can be stopped.

  In this way, when there is no other modem as a communication partner on the power line 19, the standby power of the modem can be reduced by stopping the transmission of the communication control signal from the modem. Further, unnecessary electric field radiation can be suppressed, and the influence on wireless communication in an interference state can be reduced.

  Further, the modem P3 is configured such that power line communication can be resumed when a communication control signal is received from another modem while transmission of the communication control signal is stopped by the signal stop unit. Can do. Thereby, the power line communication can be resumed when necessary.

As described above, the modems P1 and P2 may be configured to stop transmission of the communication control signal when there is no communication partner on the power line. Further, the modem P3 may be configured to stop transmission of power line communication signals depending on the link state of the modem on the Ethernet side.
In addition, it should be considered that the embodiment disclosed this time is merely illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is an overall configuration diagram of an example of a power line communication network system. It is a functional block diagram of a power line communication apparatus. It is a figure explaining the usage example of a power line communication apparatus.

Explanation of symbols

4 PC 5 Transformer 6 Photoelectric converter (media converter)
7 Optical fiber 8 Medium voltage distribution line 9 Power line 9a, 9b
9c Home power line 10 Power outlet 11 Refrigerator (information home appliance)
19 power line 21 power cord 22 power plug 23 power supply circuit 24 PLC transmission / reception unit 25 digital signal processing unit 25a Ethernet link detection unit 25b PLC link detection unit 25c signal stop unit 25d timer unit 25e signal restart unit 30 coupler 32 ether transmission / reception unit 34 personal computer 35 Ether Cable 41 Information Appliances 42 Ether Link Switch 43 Ethernet I / F
50 Broadband router 51 Ethernet I / F of router
52 Router wireless LAN I / F
53 Router 60 Ethernet side cable 61 Ethernet connector a1 to a3 A home PLC modem b1 to b3 B home PLC modem c1 to c3 C home PLC modem A A home B B home C C home P1, P2
P3 PLC modem S1, S2 Signal line (Ether cable)

Claims (6)

A power line communication device that is connected to a terminal device that performs power line communication and performs communication using the power line as a signal transmission path,
Link state detecting means for detecting a link state with the terminal device;
Signal stop means for stopping transmission of a signal for power line communication to the power line when it is detected by the link state detection means that the link with the terminal device is down;
A power line communication apparatus comprising:   The signal restarting means for restarting transmission of a signal for power line communication to the power line when the link state detecting means detects that the link with the terminal device is up. A power line communication device according to claim 1. A power line communication device used in a power line communication network including a plurality of power line communication devices that perform communication using a power line as a signal transmission path,
A PLC transmission / reception unit capable of transmitting / receiving a communication control signal for controlling communication in the network;
Control signal stopping means for stopping transmission of a communication control signal to the power line when there is no other power line communication device as a communication partner on the power line;
A power line communication apparatus comprising:   The power line communication device according to claim 3, further comprising control signal restarting means for restarting transmission of a communication control signal to the power line when a power line communication device as a communication partner appears on the power line.   A timer means for measuring the time of the non-link state with another power line communication device, the control signal stop means, when the time of the non-link state after activation of the power line communication device exceeds a predetermined time, The power line communication apparatus according to claim 3 or 4, wherein transmission of a communication control signal to the power line is stopped.   The power line communication is resumed when a communication control signal is received from another power line communication device while transmission of the communication control signal is stopped by the control signal stop unit. The power line communication apparatus in any one of 3-5.

Images