JP2008193307A - Power line communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide power line communication equipment which allows a power outlet to which a modem is connected to be changed without interrupting power line communication. <P>SOLUTION: The power line communication equipment P1 for performing communication using a power line as a signal transmission line is provided with: an antenna 31 capable of receiving a radio signal leaked from the power line and transmitting a power line communication signal to the power line; an RF transmission and reception part 32 for performing modulation/demodulation of the radio signal and the power line communication signal transmitted and received via the antenna 31; and a battery 33 for operating the antenna 31 and the RF transmission and reception part 32. <P>COPYRIGHT: (C)2008,JPO&INPIT

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.

  A general modem used for power line communication includes a PLC transmission / reception unit that performs processing such as modulation / demodulation of a signal for PLC communication transmitted / received via a power line in a housing formed of a casing, and control of the PLC transmission / reception unit. A digital signal processing unit for processing transmission / reception data and the like, and a power supply unit for operating these PLC transmission / reception units and digital signal processing unit are provided. A power connector to which the other end of the power cord having a power plug at one end that can be connected to a power outlet disposed in the house is connected to the side surface of the housing. The power cord is connected to the power source unit and the PLC transmission / reception unit via a coupler that superimposes a PLC signal on a power line in the housing.

  The modem is used by being connected to a terminal device such as a personal computer in the house, but if you want to use the terminal device in another room, or if you move the modem due to the situation of an empty outlet even in the same room Needs to change the power outlet to which the modem is connected. In this case, unplug the power plug from the old power outlet, plug it into the new power outlet, and then restart the modem.

Japanese Patent Laid-Open No. 10-145265

  However, communication cannot be performed with the power plug disconnected from the power outlet. For example, in an application such as an IP phone or an online game, there is a disadvantage that the session is disconnected when the modem is restarted.

  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 capable of changing a power outlet to which a modem is connected without interrupting power line communication.

A power line communication device according to a first aspect of the present invention is a power line communication device that performs communication using a power line as a signal transmission path,
An antenna capable of receiving a radio signal leaking from the power line and wirelessly transmitting a power line communication signal to the power line;
An RF transceiver for performing modulation / demodulation of the radio signal and the power line communication signal transmitted and received via the antenna;
A battery for operating the antenna and the RF transceiver;
It is characterized by having.

  The power line communication apparatus (modem) according to the first aspect of the present invention can receive a radio wave signal leaking from the power line (hereinafter also referred to as “leakage electric field”) and can wirelessly transmit a power line communication signal to the power line. Since it has an antenna and an RF transmission / reception unit for modulating / demodulating the radio wave signal and the power line communication signal transmitted / received via the antenna, unplug the power plug of the power cord connected to the modem from the power outlet Then, power line communication can be performed with the power line by superimposing a radio signal from the antenna attached to the modem on the power line. And the electric power for operating the said antenna and RF transmission / reception part is supplied from a battery.

  In power line communication, a leakage electric field from the power line is generated, but by receiving this leakage electric field with the antenna, wirelessly transmitting the power line communication signal with the antenna and wirelessly transmitting to the power line, and superimposing the signal on the power line, Even when the power plug is not connected to the power outlet, the power line communication can be performed while maintaining the link state of the modem.

  The leakage electric field in the house is different from outside the house where other noises exist, and other noises (mainly noise entering from the outside) are small due to the shielding effect by the wall, so that it can be used for wireless power line communication. However, in the case of wireless communication, it is conceivable that the communication speed is reduced due to the influence of noise as compared with power line communication in which a signal is directly injected into the power line and a signal is directly extracted from the power line. However, applications such as IP phones and online games that are considered to be particularly affected by interruptions in power line communication have a relatively small amount of data (communication load), so even wireless power line communication can be handled practically enough. It is.

A power line communication device according to a second aspect of the present invention is a power line communication device that performs communication using a power line as a signal transmission path,
Each having a plurality of power cords connected to the coupling portion of the power line communication device; and
A power supply unit corresponding to each power cord is provided.

  The power line communication device (modem) according to the second aspect of the present invention has a plurality of power cords each connected to the coupling portion of the power line communication device, and a power source corresponding to each power cord. Department. As a result, when moving the modem, connect a power cord other than the one that is currently connected to the power outlet to a power outlet that is located near the destination, and then connect the power cord that is currently connected to the power outlet. By pulling out from the modem, it is possible to move the modem while maintaining the link state of the modem. Such a modem is suitable for maintaining a link state mainly during a short distance movement such as a movement in a room.

  According to the power line communication apparatus of the present invention, the power outlet to which the modem is connected can be changed without interrupting the power line communication.

  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 9a, 9b, 9c, and the parent modems a1, b1, c1, and the personal computer 4 as a terminal device are connected to the power outlet 10. Child modems (power line communication devices serving as child devices) a2, a3, b2, b3, c2, and c3 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 according to the embodiment of the present invention. Since the basic function of the modem is common to the parent modem and the child modem, the parent modem will be described below as a representative.

  A modem P1 shown in FIG. 2 has a power supply 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 P1. It is configured to be connectable to the outlet 10. Although not shown, 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 (registered trademark) side cable are connected to the side surface of the casing. An ether connector is provided.

  The power cord 21 is connected to the coupling unit 30 and the power source unit 23 that superimpose the PLC signal on the power line in the casing. Connected to the coupling unit 30 is a PLC transmission / reception unit 24 that performs processing such as modulation / demodulation of a signal for PLC communication transmitted / received via a power line. The modem P1 includes a digital signal processing unit 25 that controls the PLC transmission / reception unit 24 and processes transmission / reception data.

  The modem P1 according to the present embodiment is further connected to the antenna 31 that can receive a leakage electric field from the power line and can transmit a power line communication signal to the power line. An RF transmission / reception unit 32 that performs modulation / demodulation of a power line communication signal transmitted / received via the antenna, and a battery 33 for operating the antenna 31 and the RF transmission / reception unit 32. The battery 33 is connected to the power supply unit 23 and stores electric power via the power supply unit 23.

  Further, the PLC transmission / reception unit 24 and the RF transmission / reception unit 32 are connected to a changeover switch unit 34, and the changeover switch unit 34 switches between wired power line communication and wireless power line communication. For this switching, for example, a detection unit such as a voltage detection unit capable of detecting an output from the power supply unit 23 to the changeover switch unit 34 is provided during wiring from the power supply unit 23 to the changeover switch unit 34. This can be done by detecting that the plug 22 is pulled out of the power outlet 20 and the voltage of the power supply unit 23 has dropped.

  The modem P1 performs communication by a frequency multiplexing method using a plurality of carriers (multicarrier) in a predetermined frequency band for power line communication. Specifically, the modem P1 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.

  Since the modem P1 according to the present embodiment includes the antenna 31 and the RF transmitting / receiving unit 32 as described above, when the power plug 22 of the power cord 21 connected to the modem P1 is pulled out from the power outlet 10, By switching to the wireless mode by the changeover switch unit 34 and superimposing a wireless signal from the antenna 31 attached to the modem P1 on the power line, power line communication can be performed with the power line.

As described above, the leakage electric field in the house is different from outside the house where other noises exist, and there is little other noise (mainly noise entering from outside) due to the shielding effect by the wall, so it should be used for wireless power line communication. Can do.
FIG. 4 shows an example of data on the leakage electric field of the power line communication signal in the apartment. For the measurement of the leakage electric field, a loop antenna (6502 active loop antenna (trade name) manufactured by EMCO) having a diameter of 60 cm is used. In FIG. 4, thick lines and thin lines represent the intensities of leakage electric field and background noise, respectively. In this case, an SN ratio of about 15 dB is obtained on the average of the 2 to 30 Mz section. And this S / N ratio is a magnitude | size from which the value of about 10-30 Mbps is obtained by UDP effective rate. The S / N ratio and the UDP effective speed vary depending on the antenna used, and the S / N ratio obtained with a low-sensitivity antenna deteriorates.

  FIG. 3 is a functional block diagram of a modem P2 according to another embodiment of the present invention. The modem P2 has two power cords 41a and 41b, and includes power supply units 43a and 43b corresponding to the power cords 41a and 41b. The power cords 41a and 41b are both connected to the coupling unit 40 and the power source units 43a and 43b that superimpose the PLC signal on the power line. Connected to the coupling unit 40 is a PLC transmission / reception unit 44 that performs processing such as modulation / demodulation of a signal for PLC communication transmitted / received via a power line. Further, the modem P2 includes a digital signal processing unit 45 that controls the PLC transmission / reception unit 44 and processes transmission / reception data.

The modem P2 according to the present embodiment is connected to the two power cords 41a and 41b, and the power supply units 43a and 43b corresponding to the respective power cords 41a and 41b are provided. Connect the power cord other than the power cord currently connected to the power outlet to the power outlet installed near the destination, and then pull the currently connected power cord out of the power outlet. The modem P2 can be moved while maintaining the link state of P2.
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 one embodiment of a modem of the present invention. It is a functional block diagram of other embodiment of the modem of this invention. It is a figure which shows the example of data of the leakage electric field in a house.

Explanation of symbols

9 power line 10 power outlet 21 power cord 22 power plug 23 power supply unit 24 PLC transmission / reception unit 25 digital signal processing unit 30 coupling unit 31 antenna 32 RF transmission / reception unit 34 changeover switch unit 40 coupling unit 41a power cord 41b power cord 43a power source unit 43b power source 44 PLC transmission / reception unit 45 Digital signal processing unit P1, P2 PLC modem

Claims (2)

A power line communication device that performs communication using a power line as a signal transmission path,
An antenna capable of receiving a radio signal leaking from the power line and wirelessly transmitting a power line communication signal to the power line;
An RF transceiver for performing modulation / demodulation of the radio signal and the power line communication signal transmitted and received via the antenna;
A battery for operating the antenna and the RF transceiver;
A power line communication device comprising: A power line communication device that performs communication using a power line as a signal transmission path,
Each having a plurality of power cords connected to the coupling portion of the power line communication device; and
A power line communication device comprising a power supply unit corresponding to each power cord.

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