JP2017157973A - Communication apparatus and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication apparatus capable of reducing communication interferences on other network while preventing degradation of transmission efficiency in own network.SOLUTION: The communication apparatus is included in a first network and is capable of being connected to a transmission channel to which another communication apparatus included in a second network is connected. The communication apparatus receives a second signal transmitted from other communication apparatus, measures the signal strength of the second signal and controls the transmission on the basis of the signal strength, and transmits a first signal according to the control.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a communication device and a communication method.

  Conventionally, a power line communication apparatus using a power line as a signal transmission path has been performed. The following devices are known as conventional power line communication devices. This power line communication apparatus monitors the operating state (the presence / absence of operation, the value of transmission gain, etc.) of power line communication apparatuses belonging to other networks. The power line communication device communicates with power line communication devices belonging to other networks using a frequency band different from the frequency band (2 to 30 MHz) used for data communication. Thereby, the power line communication device acquires the operating state of the power line communication device belonging to another network, adjusts the transmission gain based on the acquired operating state, and avoids interference between adjacent network groups.

JP 2007-259176 A

  In the power line communication device described in Patent Literature 1, it is difficult to reduce communication interference with other networks and suppress a decrease in transmission efficiency in the own network.

  The present disclosure has been made in view of the above circumstances, and provides a communication device and a communication method capable of reducing communication interference with other networks and suppressing a decrease in transmission efficiency in the own network.

  The communication device according to the present disclosure is a communication device belonging to the first network that can be connected to a transmission path to which another communication device belonging to the second network is connected, and is a second device transmitted from the other communication device. A receiving circuit that receives the first signal, a measuring circuit that measures the signal strength of the second signal, a control circuit that controls transmission based on the signal strength, and a first signal that is transmitted according to control by the control circuit A transmission circuit.

  A communication method according to the present disclosure is a communication method of a first communication device belonging to a first network that can be connected to a transmission path to which a second communication device belonging to a second network is connected. The second signal transmitted from the communication device is received, the signal strength of the second signal is measured, and the first signal is transmitted or stopped based on the signal strength.

  According to the present disclosure, it is possible to reduce communication interference with other networks and suppress a decrease in transmission efficiency in the own network.

Schematic diagram showing a configuration example of a communication system in the first embodiment Block diagram showing a hardware configuration example of a PLC device Block diagram showing a hardware configuration example of a PLC / PHY block The flowchart which shows an example of the transmission operation | movement procedure of a PLC apparatus. Schematic diagram showing a first connection form of a communication system Schematic diagram showing a second connection form of the communication system Schematic diagram showing a third connection form of the communication system Schematic diagram showing the fourth connection form of the communication system Schematic diagram showing the fifth connection form of the communication system Schematic diagram showing the sixth connection form of the communication system

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the claimed subject matter.

(Background to obtaining one form of the present disclosure)
In a conventional power line communication device, when a power line communication device belonging to another network operates, the transmission gain is uniformly suppressed to avoid interference between networks. However, when the intensity of a signal transmitted from a power line communication device belonging to another network is low, this signal is considered to be a noise having a small influence (low level) for the power line communication device belonging to the own network. In other words, the signal transmitted from the power line communication device belonging to the own network becomes noise having a small influence (low level) similarly for the power line communication device belonging to another network. That is, there is little risk of adverse effects on communication within each other's network by both signals between the local network and the other network. In this case, if the transmission gain is uniformly suppressed, the S / N ratio of the signal transmitted within the own network is lowered, and on the contrary, it causes frequent transmission errors and retransmissions.

  Hereinafter, a communication device and a communication method capable of reducing communication interference with other networks and suppressing a decrease in transmission efficiency in the own network will be described.

(First embodiment)
[Configuration etc.]
FIG. 1 is a schematic diagram illustrating a configuration example of a communication system 5 according to the first embodiment. In the communication system 5, a plurality of PLC (Power Line Communication) devices 10 are connected to the power line 1A. The PLC device 10 performs power line communication in conformity with, for example, the standard of IEEE (The Institute of Electrical and Electronics Engineers) 1901. The PLC device 10 is an example of a communication device.

  The PLC device 10 may be, for example, a PLC modem or an electric device incorporating a PLC modem. The electrical equipment may include, for example, home appliances such as a television, a telephone, a video deck, and a set top box, and office equipment such as a personal computer, a facsimile, and a printer. Further, the PLC device 10 may include an infrastructure device such as a smart meter, and an IoT (Internet of Things) device such as a security camera and a sensor device.

  FIG. 2 is a block diagram illustrating a hardware configuration example of the PLC device 10. The PLC device 10 includes a circuit module 30 and a switching power supply 20.

  The switching power supply 20 supplies various voltages (for example, +1.2 V, +3.3 V, and +12 V) to the circuit module 30. The switching power supply 20 includes, for example, a switching transformer and a DC-DC converter (both not shown). Power to the switching power supply 20 is supplied from the power connector 21 via the impedance upper 27 and the AC / DC converter 24. For example, the power connector 21 is provided on the back surface of the casing 100 of the PLC device 10.

  The circuit module 30 includes a main IC (Integrated Circuit) 11 and an AFE / IC (Analog Front END / Integrated Circuit) 12. The circuit module 30 includes a low pass filter (LPF) 13, a driver IC 15, a coupler 16, a band pass filter (BPF: Band Pass Filter) 17, and a memory 18. Further, the circuit module 30 includes an Ethernet (registered trademark) PHY IC (Physical Layer Integrated Circuit) 19 and an AC cycle detector 60.

  The coupler 16 is connected to the power connector 21 and further connected to the power line 1A via the power cable 1B, the power plug 25, and the outlet 2. The LED 23 operates as a display unit and is connected to the main IC 11. Connected to the modular jack 22 is a LAN cable 26 for connection to various devices (for example, a personal computer). The modular jack 22 is provided on the back surface of the housing 100, for example. LED23 is provided in the front surface of the housing | casing 100, for example.

  The main IC 11 includes a CPU (Central Processing Unit) 11A and a PLC / MAC (Power Line Communication / Media Access Control layer) block 11C1, 11C2. The main IC 11 includes PLC / PHY (Power Line Communication / Physical Layer) blocks 11B1 and 11B2.

  The CPU 11A mounts a 32-bit RISC (Reduced Instruction Set Computer) processor. The PLC / MAC block 11C2 manages the MAC layer (Media Access Control layer) of the transmission signal. The PLC / MAC block 11C2 includes a transmission control circuit 61 (see FIG. 3) that controls transmission of a signal frame (also simply referred to as a frame) and calculates a retransmission rate of the frame. The PLC / MAC block 11C1 manages the MAC layer of the received signal.

  The PLC / PHY block 11B2 manages a PHY layer (Physical layer) of a transmission signal. The PLC / PHY block 11B2 includes a transmission circuit 63 (see FIG. 3) that transmits a frame. For example, when transmitting a frame to the first network NW1, the transmission circuit 63 includes the phase vector of the first network NW1 in the preamble and transmits the frame. The PLC / PHY block 11B1 manages the PHY layer of the received signal.

  The AFE / IC 12 includes a DA converter (DAC: Digital to Analog Converter) 12A, an AD converter (ADC: Analog to Digital Converter) 12D, and a variable amplifier (VGA: Variable Gain Amplifier) 12B, 12C.

  The coupler 16 includes a coil transformer 16A and coupling capacitors 16B and 16C. The CPU 11A uses the data stored in the memory 18 to control the operation of the PLC / MAC blocks 11C1 and 11C2 and the PLC / PHY blocks 11B1 and 11B2, and controls the entire PLC device 10.

  In FIG. 2, the PLC device 10 includes the PLC / MAC blocks 11C1 and 11C2 and the PLC / PHY blocks 11B1 and 11B2, which are used for transmission and reception, respectively. Instead, the PLC device 10 may include a PLC / MAC block 11C and a PLC / PHY block 11B (not shown), and may be used for both transmission and reception.

  The PLC / MAC blocks 11C1 and 11C2 are also simply referred to as a PLC / MAC block 11C. The PLC / PHY blocks 11B1 and 11B2 are also simply referred to as a PLC / PHY block 11B.

  The main IC 11 is an electric circuit (LSI: Large Scale Integration) that performs signal processing including basic control or modulation / demodulation for data communication, for example, as with a general modem. For example, the main IC 11 modulates reception data output from a communication terminal (for example, a PC) via the modular jack 22 and outputs the data to the AFE / IC 12 as a transmission signal (data). Further, the main IC 11 demodulates a signal input from the power line 1A side via the AFE / IC 12 as a received signal (data), and outputs it to the communication terminal (for example, PC) via the modular jack 22.

  The AC cycle detector 60 generates a synchronization signal necessary for each PLC device 10 to control at a common timing. The AC cycle detector 60 includes a diode bridge 60a, resistors 60b and 60c, a DC (Direct Current) power supply unit 60e, and an operational amplifier 60d.

  The diode bridge 60a is connected to the resistor 60b. The resistor 60b is connected in series with the resistor 60c. The resistors 60b and 60c are connected in parallel to one terminal of the operational amplifier 60d. The DC power supply unit 60e is connected to the other terminal of the operational amplifier 60d.

  Specifically, the generation of the synchronization signal by the AC cycle detector 60 is performed as follows. That is, the zero cross point of the voltage of the AC power waveform AC (AC waveform consisting of a sine wave of 50 Hz or 60 Hz) of the commercial power supplied to the power line 1A is detected, and a synchronization signal is generated with reference to the timing of the zero cross point. As an example of the synchronization signal, a rectangular wave composed of a plurality of pulses synchronized with the zero cross point of the AC power waveform can be cited.

  The AC cycle detector 60 is not essential. In this case, the synchronization between the PLC devices 10 uses, for example, a synchronization signal included in the communication signal.

  Communication by the PLC device 10 is performed as follows. Data input from the modular jack 22 is sent to the main IC 11 via the Ethernet (registered trademark) PHY IC 19 and digital signal processing is performed to generate a digital signal. The generated digital signal is converted into an analog signal by the DA converter 12A of the AFE / IC 12. The converted analog signal is output to the power line 1A via the low-pass filter 13, the driver IC 15, the coupler 16, the power connector 21, the power cable 1B, the power plug 25, and the outlet 2.

  The signal received from the power line 1A is sent to the bandpass filter 17 via the coupler 16, and after gain adjustment by the variable amplifier 12C of the AFE / IC 12, it is converted to a digital signal by the AD converter 12D. . The converted digital signal is sent to the main IC 11 and converted into digital data by performing digital signal processing. The converted digital data is output from the modular jack 22 via the Ethernet (registered trademark) PHY IC 19.

  FIG. 3 is a block diagram illustrating a hardware configuration example of the PLC / PHY block 11B1.

  The PLC / PHY block 11B1 includes a time / frequency conversion circuit 51, a gain control circuit 52, a preamble detection circuit 53, a preamble detection circuit 54, an RSSI (Received Signal Strength Indicator) calculation circuit 55, and a preamble detection control circuit 56.

  The time / frequency conversion circuit 51 converts time axis data of a frame received from the network into frequency axis data. In this transformation, for example, Fourier transformation or wavelet transformation is performed.

  The gain control circuit 52 adjusts the gain of the variable amplifier 12C and outputs the gain value to the RSSI calculation circuit 55.

  Preamble detection circuits 53 and 54 are provided for each network and detect the preamble of the frame. Here, two networks are shown as an example, but there may be three or more networks. In this case, the same number of preamble detection circuits as the number of networks (including the own network) are provided.

  The frame includes a preamble, a frame control, and a payload. The preamble includes a phase vector for specifying the network. The phase vector is set to a value such as “0” or “π” for each subcarrier. On the receiving side, for example, when the signal carried by the subcarrier is multiplied by the opposite phase, the original signal is obtained. The setting of the phase vector is performed by, for example, the PLC / MAC block 11C1.

  Preamble detection circuits 53 and 54 compare the stored phase vector and the phase vector included in the preamble of the received frame, respectively, to determine which network the received frame is transmitted from. Identify

  For example, when the preamble detection circuit 53 detects the phase vector A indicating that the frame is from the network A, the preamble detection circuit 53 notifies the preamble detection control circuit 56 of the detection flag. Similarly, when the preamble detection circuit 54 detects the phase vector B indicating that the signal is transmitted from the network B, for example, the preamble detection circuit 54 notifies the preamble detection control circuit 56 of the detection flag.

  In this embodiment, the number of preamble detection circuits is the same as the number of networks (including its own network). However, one preamble detection circuit may identify a plurality of networks.

  The RSSI calculation circuit 55 calculates the RSSI of a frame transmitted from any network based on the gain value output from the gain control circuit 52 and the time axis data output from the time / frequency conversion circuit 51. The RSSI value is an example of signal strength, and other signal strengths may be calculated.

  The preamble detection control circuit 56 compares the RSSI value calculated by the RSSI calculation circuit 55 with the threshold value th of the network notified of the detection flag. When the RSSI value is larger than the threshold th, the preamble detection control circuit 56 sends a detection notification to the transmission control circuit 61 in the PLC / MAC block 11C2. The threshold th includes, for example, thresholds tha, thb,. The threshold th is held in, for example, a memory (not shown) of the PLC / PHY block 11B1.

  For example, when the detection flag of the network A is set and the RSSI value of the signal from the network A is larger than the threshold value tha, the preamble detection control circuit 56 notifies the transmission control circuit 61 that a frame exceeding the threshold value tha has been detected. Notice. Similarly, when the detection flag of the network B is set and the RSSI value of the signal from the network B is larger than the threshold thb, the preamble detection control circuit 56 indicates that the frame signal exceeding the threshold thb has been detected. 61 is notified.

  The thresholds tha and thb may be set to different values for each network, or may be set to the same value. The threshold th may be a fixed value or may be dynamically changed. Further, when there are three or more preamble detection circuits, the threshold th may be three or more.

  The transmission control circuit 61 uses, for example, a retransmission rate when dynamically changing the threshold th. For example, the transmission control circuit 61 calculates a retransmission rate and sets the threshold th to decrease when the retransmission rate increases, and increases the threshold th when the retransmission rate decreases.

  That is, when the retransmission rate increases, if the threshold th is high, it is difficult to detect frames from other networks (for example, the second network NW2) other than the own network (first network NW1), and interference is likely to occur. Therefore, in this case, the transmission control circuit 61 controls frame transmission by lowering the threshold th. As a result, the PLC device 10 can easily detect a frame from another network and can prevent interference.

  On the other hand, when the retransmission rate decreases, the transmission control circuit 61 increases the threshold th, so that it is difficult to detect frames from other networks, so that transmission efficiency can be improved.

  When receiving a detection notification from the preamble detection control circuit 56, the transmission control circuit 61 controls the transmission circuit 63 in the PLC / PHY block 11B2 not to transmit a frame to be transmitted. Further, when the transmission control circuit 61 does not receive the detection notification from the preamble detection control circuit 56, the transmission control circuit 61 continues the frame transmission control to the transmission circuit 63 in the PLC / PHY block 11B2. Specifically, the transmission control circuit 61 continues counting the back-off time of the frames stored in the queue. When the count of the back-off time is completed, the transmission control circuit 61 transmits the frame stored in the queue. Note that the transmission control circuit 61 may control the transmission circuit 63 so that the transmission intensity is lowered instead of transmitting the frame.

  The transmission circuit 63 transmits or does not transmit a frame in accordance with an instruction from the transmission control circuit 61. Further, the transmission circuit 63 transmits a frame with a reduced transmission intensity in accordance with an instruction from the transmission control circuit 61.

[Operation etc.]
Next, an operation example of the PLC device 10 will be shown.
FIG. 4 is a flowchart showing a transmission operation procedure of the PLC device 10. The process of FIG. 4 is performed periodically.

  The PLC / PHY block 11B1 in the PLC device 10 receives a frame from a network including its own network and other networks (S1). The RSSI calculation circuit 55 calculates an RSSI value related to reception of this frame (S2).

  The preamble detection circuits 53 and 54 determine whether or not a phase vector included in the preamble of the received frame is detected (S3).

  When the preamble phase vector is not detected, the preamble detection control circuit 56 continues the frame transmission control (S9). Therefore, for example, the back-off time is continuously counted.

  When the phase vector of the preamble is detected and is the phase vector A, the preamble detection control circuit 56 acquires the threshold value tha from the memory (not shown) (S4). When the phase vector of the preamble is detected and is the phase vector B, the preamble detection control circuit 56 acquires the threshold thb from the memory (not shown) (S5).

  The preamble detection control circuit 56 determines whether or not the calculated RSSI value is larger than a threshold th corresponding to another network that has transmitted the frame (S6). When the RSSI value is equal to or less than the above threshold th, the preamble detection control circuit 56 continues frame transmission control (S9).

  On the other hand, when the RSSI value is larger than the threshold th, the preamble detection control circuit 56 detects the preamble of the received frame (S7). Then, the preamble detection control circuit 56 stops the frame transmission control (S8). Therefore, for example, the count of the back-off time is temporarily stopped. Thereafter, the PLC device 10 ends this operation.

  The transmission circuit 63 in the PLC / MAC block 11C2 transmits the frame after a predetermined back-off time, for example, according to the frame transmission control.

  Thus, when the RSSI value of a frame from another network exceeds the threshold th, the PLC device 10 can suppress the transmission error and the retransmission by stopping the frame transmission control by the PLC device 10.

[Communication system connection form]
Next, variations of the connection form of the communication system 5 including the PLC device 10 will be described. Variations of the communication system 5 are referred to as communication systems 5A, 5B,. Moreover, PLC apparatus 10A, 10B, 10C, ..., etc. are examples of the PLC apparatus 10, The structure is the same as that of the PLC apparatus 10. FIG.

(First connection form)
FIG. 5 is a schematic diagram showing a first connection form of the communication system 5A.

  The communication system 5A is provided in an apartment, for example. In the communication system 5A, a transformer TS1 that converts a high voltage (for example, 6600 V) and a low voltage (for example, 200 V) applied to an external high-voltage electric wire PL is installed outside the house. The transformer TS1 is connected to a breaker BR1 installed in the house.

  The breaker BR1 includes switches SW1 and SW2. The switch SW1 is switched to cut off / open commercial AC supplied to the power line 1A1 wired in the house (for example, one room of an apartment). Similarly, the switch SW2 switches off / open commercial AC supplied to another power line 1A2 wired in the house (for example, another room of the same apartment).

  In the power line 1A1, a first network (own network) NW1 to which the PLC device 10 is connected is formed in a range corresponding to one room of an apartment, for example. A second network NW2 to which the PLC device 10B is connected is formed in the power line 1A2 in a range corresponding to, for example, another room of an apartment. The first network NW1 is connected to the second network NW2 via the switches SW1 and SW2 in the breaker BR1.

  The breaker BR1 connects between the first network NW1 and the second network NW2 via the switches SW1 and SW2. The amount of frame attenuation when passing through the breaker BR1 is small.

  On the other hand, the transformer TS1 connects between the first network NW1 and the second network NW2. If a frame is transmitted via the transformer TS1, the amount of frame attenuation is large. The transformer TS1 includes a winding having a frequency of 50 Hz or 60 Hz and a winding ratio for stepping down a voltage of 6600 V to a voltage of 200 V and an iron core. Therefore, in the transformer TS1, the frequency and impedance of the PLC signal using 2 MHz to 30 MHz are mismatched, and the signal is easily attenuated.

  In the communication system 5A, the first network NW1 and the second network NW2 are connected via the breaker BR1 without passing through the transformer TS1. Therefore, in the communication system 5A, the attenuation amount of the signal transmitted between the first network NW1 and the second network NW2 is small.

  In this case, the threshold value th when the PLC device 10 connected to the first network NW1 detects the preamble included in the frame from the PLC device 10B connected to the second network NW2, and the first network NW1 The threshold th when detecting the preamble included in the frame from the other PLC device 10A connected to is set to the same value.

  Also, the threshold value th used by the PLC device 10B connected to the second network NW2 is set to the same value as the threshold value th used by the PLC device 10.

  Thus, when the amount of attenuation between the networks is small, the signal enters the first network NW1 with the signal strength of the frame from the second network NW2 maintained, so communication with the communication in the first network NW1 Interference is likely to occur.

  Accordingly, the PLC device 10 increases the frequency of the preamble detection operation that is likely to be detected by setting the threshold th when detecting the preamble included in the frame from the second network NW2 to a small value. Thus, transmission errors and retransmissions can be suppressed.

  A contractor such as an apartment may set the threshold th through the PLC device 10 or PC (not shown), or the user may set the threshold th through the PLC device 10 or PC (not shown). May be set.

(Second connection form)
FIG. 6 is a schematic diagram showing a second connection form of the communication system 5B.

  In the communication system 5B, the first network NW1 and the second network NW2 are connected without passing through the transformer TS1 and the breaker BR1. That is, the first network NW1 to which the PLC device 10 is connected is formed in a range corresponding to the four rooms of the apartment without using the breaker BR1. Similarly, the second network NW2 to which the PLC device 10B is connected is formed in a range corresponding to a plurality of rooms of the apartment without using the breaker BR1.

  Therefore, in the communication system 5B, similarly to the communication system 5A, the attenuation amount of the frame transmitted between the first network NW1 and the second network NW2 is small. The setting of the threshold th when detecting the preamble is the same as in the communication system 5A. Thereby, the PLC device 10 can increase the frequency of the preamble detection operation that is likely to be detected, and can suppress the occurrence of transmission errors and retransmissions.

(Third connection form)
FIG. 7 is a schematic diagram showing a third connection form of the communication system 5C.

  In the communication system 5C, two transformers TS1A and TS1B for converting a high voltage and a low voltage applied to the external high-voltage electric wire PL are installed outside the house.

  The transformer TS1A is connected to a breaker BR1A installed in the house. Breaker BR1A incorporates switches SW1 and SW2. The switch SW1 switches off / open commercial AC supplied to the power line 1A1 wired in the house. Similarly, the switch SW2 switches off / open of commercial AC supplied to another power line 1A2 wired in the house. A first network NW1 to which the PLC device 10 is connected is formed on the power line 1A1 and the power line 1A2 without using the breaker BR1A.

  The transformer TS1B is connected to a breaker BR1B installed in the house. Breaker BR1B includes switches SW3 and SW4. The switch SW3 switches off / open commercial AC supplied to the power line 1A3 wired in the house. Similarly, the switch SW4 switches off / open of commercial AC supplied to another power line 1A4 wired in the house. A second network NW2 is formed in the power line 1A3 and the power line 1A4 without using the breaker BR1B.

  In the communication system 5C, the first network NW1 is connected to the second network NW2 via the switches SW1 and SW2 in the breaker BR1A, the transformers TS1A and TS1B, and the switches SW3 and SW4 in the breaker BR1B. Breaker BR1 is connected to an external high voltage electric wire PL via transformers TS1A and TS1B.

  In the communication system 5C, transformers TS1A and TS1B are interposed between the first network NW1 and the second network NW2. Therefore, the attenuation amount of the frame signal transmitted between the first network NW1 and the second network NW2 is large.

  In this case, the threshold value th when the PLC device 10 connected to the first network NW1 detects the preamble included in the frame from the PLC device 10B connected to the second network NW2 is the first network NW1. Is set to a value larger than the threshold th when detecting a preamble included in a frame from another PLC device 10A connected to the. This large value is, for example, the amount of attenuation between the first network NW1 and the second network NW2 + α (α: correction value).

  Thus, when the amount of attenuation between the networks is large, the signal strength of the frame from the second network NW2 becomes small in the transformers TS1A and TS1B, and interference with communication in the first network NW1 hardly occurs. .

  Therefore, the PLC device 10 can omit the preamble detection operation that is likely to be non-detected by setting the threshold th when detecting the preamble included in the frame from the second network NW2 to a large value. , Transmission efficiency can be increased.

  As for the threshold value th used by the PLC device 10B connected to the second network NW2, the threshold value th for detecting the preamble included in the frame from the first network NW1 is set to a large value.

(4th connection form)
FIG. 8 is a schematic diagram showing a fourth connection form of the communication system 5D.

  In the communication system 5D, the first network NW1 and the second network NW2 are connected via the power lines 1A1, 1A2, 1B1, and 1B2 without passing through the transformers TS1A and TS1B and the breakers BR1A and BR1B.

  In FIG. 8, the first network NW1 to which the PLC device 10 is connected is formed in a range corresponding to four rooms of an apartment without going through the breakers BR1A and BR1B. Similarly, the second network NW2 to which the PLC device 10B is connected is formed in a range corresponding to four rooms of an apartment without going through the breakers BR1A and BR1B.

  Therefore, in the communication system 5D, similarly to the communication system 5B, the amount of attenuation of a frame transmitted between the first network NW1 and the second network NW2 is small. Setting of the threshold th when detecting the preamble is the same as that of the communication system 5B. The PLC device 10 can increase the frequency of the preamble detection operation that is likely to be detected, and can suppress the occurrence of transmission errors and retransmissions.

(5th connection form)
FIG. 9 is a schematic diagram showing a fifth connection form of the communication system 5E.

  The arrangement of the power lines in the communication system 5E is the same as in the communication systems 5C and 5D. In the communication system 5E, in addition to the second network NW2, a third network NW3 is formed as another network.

  The third network NW3 is formed in a range corresponding to the four rooms of the apartment without using the breakers BR1A and BR1B.

  The first network NW1 and the third network NW3 are connected via the power lines 1A1 and 1A2 without passing through the transformers TS1A and TS1B and the breakers BR1A and BR1B.

  The second network NW2 and the third network NW3 are connected via the power lines 1A3 and 1A4 without passing through the transformers TS1A and TS1B and the breakers BR1A and BR1B.

  In the communication system 5E, as in the communication system 5C, the transformers TS1A and TS1B are interposed between the first network NW1 and the second network NW2, so that the first network NW1 and the second network NW2 The attenuation of frame signals transmitted between them is large.

  In this case, the threshold value th when the PLC device 10 connected to the first network NW1 detects the preamble included in the frame from the PLC device 10B connected to the second network NW2 is the first network NW1. Is set to a value larger than the threshold th when detecting a preamble included in a frame from another PLC device 10A connected to.

  Similarly, the threshold value th when the PLC device 10B connected to the second network NW2 detects the preamble included in the frame from the PLC device 10 connected to the first network NW1 is the second network NW2 Is set to a value larger than the threshold th when detecting a preamble included in a frame from another PLC device (not shown) connected to.

  As a result, the PLC device 10 can omit a preamble detection operation that is highly likely to be undetected in communication between the first network NW1 and the second network NW2, and can increase transmission efficiency.

  Further, in the communication system 5E, similarly to the communication system 5D, the attenuation amount of the frame signal transmitted between the first network NW1 and the third network NW3 is small. The setting of the threshold th when detecting the preamble is the same as that of the communication system 5D.

  Similarly, the amount of attenuation of the frame signal transmitted between the second network NW2 and the third network NW3 is small. The setting of the threshold th when detecting the preamble is the same as that of the communication system 5D.

  As a result, the PLC device 10 increases the frequency of the preamble detection operation that is likely to be detected in the communication between the first network NW1 or the second network NW2 and the third network NW3. The occurrence of retransmission can be suppressed.

(Sixth connection configuration)
FIG. 10 is a schematic diagram showing a sixth connection form in the communication system 5F.

  In the communication system 5F, a hub (concentrator) 70 connected to a LAN backbone BN (such as an optical line) is installed in a predetermined place (for example, a room of an apartment).

  The hub 70 includes a plurality of LAN modules md1 to md5 and a plurality of PLC modules 10v to 10z. The LAN modules md1 to md5 transmit and receive LAN signals (for example, Ethernet (registered trademark) signals). The PLC modules 10v to 10z transmit and receive PLC signals.

  The hub 70 converts the PLC signal obtained by the PLC modules 10v to 10z into a LAN signal and sends it to the LAN modules md1 to md5. Further, the hub 70 converts the LAN signal obtained by the LAN modules md1 to md5 into a PLC signal and sends it to the PLC modules 10v to 10z.

  The PLC modules 10v to 10z are connected to the networks NW1, NW2,... Via signal lines such as coaxial cables and twisted pair cables, respectively. In FIG. 10, the PLC devices 10 and 10A are connected to a signal line Ln1 that forms the first network NW1. The PLC devices 10B1 and 10B2 are connected to a signal line Ln2 that forms the second network NW2. Note that the number of PLC devices 10 included in each network is not two, but may be one or three or more.

  Filters F1 to F5 are provided between the LAN backbone BN and the LAN modules md1 to md5 in the hub 70. The filters F1 to F5 block the PLC signal and allow the PLC signal to pass. Since the filters F1 to F5 actively block the signal, the amount of attenuation of the signal is large like the transformer.

  In the communication system 5F, for example, the first network NW1 to which the PLC devices 10A and 10B are connected passes through the PLC module 10z and the LAN module md1 in the hub 70, and passes through the filters F1 and F2 connected to the backbone BN. The LAN module md2 and the PLC module 10y in the hub 70 are connected to the second network NW2 to which the PLC devices 10C and 10D are connected.

  In the communication system 5F, filters F1 and F2 are interposed between the first network NW1 and the second network NW2. Therefore, the attenuation amount of the frame signal transmitted between the first network NW1 and the second network NW2 is large.

  In this case, for example, the threshold value th when the PLC device 10 connected to the first network NW1 detects the preamble included in the frames from the PLC devices 10B1 and 10B2 connected to the second network NW2 is It is set to a value larger than the threshold th when detecting a preamble included in a frame from another PLC device 10A connected to one network NW1.

  Similarly, for example, the threshold value th when the PLC device 10B1 connected to the second network NW2 detects the preamble included in the frame from the PLC devices 10 and 10A connected to the first network NW1 is 2 is set to a value larger than the threshold th when detecting a preamble included in a frame from another PLC device 10B2 connected to the second network NW2.

  As a result, the PLC devices 10A to 10D can omit a preamble detection operation that is highly likely to be undetected in communication between the first network NW1 and the second network NW2, and can increase transmission efficiency.

  In each connection mode, the threshold th may be set in advance, or the threshold th may be changed at an arbitrary timing.

[Effects]
Thus, the PLC device 10 belongs to the first network NW1 that can be connected to the transmission path to which the PLC device 10B belonging to the second network NW2 is connected. The PLC device 10 includes a receiving circuit that receives the second frame transmitted from the PLC device 10B, an RSSI calculation circuit 55 that calculates (measures) the signal strength of the second frame, and a PLC device based on the signal strength. A preamble detection control circuit 56 that controls the transmission of 10 and a transmission circuit 63 that transmits the first frame in accordance with the control of the preamble detection control circuit 56.

  The PLC device 10 is an example of a communication device. The PLC device 10B is an example of another communication device. The transmission path is, for example, the power line 1A. The second frame is an example of a second signal. The receiving circuit includes, for example, a PLC / PHY block 11B1. The RSSI calculation circuit 55 is an example of a measurement circuit. The preamble detection control circuit 56 is an example of a control circuit. The first frame is an example of a first signal.

  As described above, when transmitting the first frame, the PLC device 10 considers the influence of the second frame communicated in the second network NW2, and thus suppresses adverse effects on the second network NW2. it can. For example, the PLC device 10 can suppress the interference between networks by suppressing the transmission gain uniformly during communication by measuring the signal strength of the frame from the second network NW2. Therefore, when the possibility of network interference is low, the PLC device 10 can suppress a decrease in the S / N ratio of a frame transmitted through the first network NW1, and can suppress the occurrence of transmission errors and retransmissions.

  The transmission circuit 63 may transmit the first frame using the first phase vector corresponding to the first network NW1. The receiving circuit may receive the second frame using a plurality of phase vectors including the first phase vector. The preamble detection control circuit 56, when the receiving circuit receives the second frame using the second phase vector corresponding to the second network NW2, the second frame is a frame transmitted from the second network NW2. It may be determined that

  Thereby, the PLC device 10 can easily identify the network that is the transmission source of the frame using the phase vector included in the preamble of the frame. Therefore, the PLC device 10 can easily grasp the influence due to the communication in the second network NW2.

  The preamble detection control circuit 56 may stop the transmission control of the first frame when the signal strength of the second frame calculated by the RSSI calculation circuit 55 is greater than the threshold th.

  Thereby, the PLC apparatus 10 can suppress that the communication performance of transmission of a 1st frame deteriorates by interfering with the 2nd frame from the 2nd network NW2.

  Further, the preamble detection control circuit 56 may control transmission of the first frame when the signal strength of the second frame calculated by the RSSI calculation circuit 55 is equal to or less than the threshold th.

  Thereby, the PLC device 10 can suppress the interference with the second frame from the second network NW2, and can transmit the first frame.

  Further, the transmission control circuit 61 may change the threshold th based on the retransmission rate of the first frame. The transmission control circuit 61 is an example of a control circuit.

  Thereby, the PLC apparatus 10 can determine appropriately the presence or absence of transmission of a 1st frame according to the communication condition using the transmission line.

  Further, the transmission control circuit 61 may decrease the threshold th when the retransmission rate of the first frame increases.

  Thereby, the PLC device 10 can increase the detection frequency of the second frame from the second network NW2, and makes it difficult for the first frame to be transmitted by the first network NW1 and the second network NW2. Communication interference can be suppressed.

  Also, the transmission control circuit 61 may increase the threshold th when the retransmission rate of the first frame decreases.

  Thereby, the PLC device 10 can reduce the detection frequency of the second frame from the second network NW2, and can improve the transmission efficiency in the first network NW1 and the second network NW2.

  The transmission line may be the power line 1A. As a result, even in a power line network in which noise is relatively likely to occur on the transmission path due to switching of the communication device or the like, it is possible to achieve both suppression of deterioration in communication performance and improvement in communication efficiency.

(Other embodiments)
As described above, the first embodiment has been described as an example of the technique in the present disclosure. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments in which changes, replacements, additions, omissions, and the like are performed.

  In the first embodiment, the communication device is applied to the PLC device 10 that performs power line communication. However, the communication device is not limited to power line communication, and may be applied to various communication devices that perform communication via a LAN. Good.

  In the first embodiment, the PLC device 10 indicates that the transmission is stopped when the signal strength exceeds the threshold th even once, but the transmission may be stopped when the signal strength exceeds the threshold th a plurality of times. . As a result, the PLC device 10 can appropriately control transmission even when a frame having a high signal strength is intermittently generated.

  In the first embodiment, the transmission / reception of the first frame is permitted / stopped based on the signal strength. The transmission control circuit 61 may change the gain at the time of frame transmission instead of permitting / stopping transmission.

  In the first embodiment, the transformer and the filter are shown as the electronic components having a large signal attenuation. However, other electronic components may be used. Similarly, a breaker is shown as an electronic component with a small signal attenuation, but other electronic components may be used.

  In the first embodiment, each circuit may be configured by hardware of a dedicated electric circuit or electronic circuit, or may be realized by a processor executing a predetermined program.

  The present disclosure is useful for a communication device, a communication method, and the like that can reduce communication interference with other networks and suppress a decrease in transmission efficiency in the local network.

1A, 1A1, 1A2, 1A3, 1A4 Power line 1B Power cable 2 Outlet 5, 5A, 5B, 5C, 5D, 5E, 5F Communication system 10, 10A, 10B, 10C, 10D PLC devices 10v, 10w, 10x, 10y, 10z PLC module 11 main IC
11A CPU
11B1, 11B2 PLC / PHY block 11C1, 11C2 PLC / MAC block 12 AFE / IC
12A DA converter (DAC)
12B, 12C Variable Amplifier (VGA)
12D AD converter (ADC)
13 Low-pass filter 15 Driver IC
16 Coupler 16A Coil transformer 16B, 16C Coupling capacitor 17 Band pass filter 18 Memory 19 Ethernet (registered trademark) PHY IC
20 Switching power supply 21 Power supply connector 22 Modular jack 23 LED
24 AC / DC converter 25 Power plug 26 LAN cable 27 Impedance upper 27A, 27B Coil 30 Circuit module 51 Time / frequency conversion circuit 52 Gain control circuit 53, 54 Preamble detection circuit 55 RSSI calculation circuit 56 Preamble detection control circuit 60 AC cycle detection 60a Diode bridge 60b, 60c Resistor 60d Operational amplifier 60e DC power supply 61 Transmission control circuit 63 Transmission circuit 70 Hub (concentrator)
100 Housing BN Backbone BR1, BR1A, BR1B Breakers F1 to F5 Filters md1 to md5 LAN module NW1 First network NW2 Second network NW3 Third network PL High-voltage wires SW1, SW2, SW3, SW4 Switch tha, thb Threshold TS1A, TS1B transformer

Claims (16)

A communication device belonging to the first network, connectable to a transmission path to which another communication device belonging to the second network is connected,
A receiving circuit for receiving a second signal transmitted from the other communication device;
A measurement circuit for measuring the signal strength of the second signal;
A control circuit for controlling transmission based on the signal strength;
A transmission circuit for transmitting the first signal in accordance with control by the control circuit;
A communication device comprising: The communication device according to claim 1,
The transmission circuit transmits the first signal using a first phase vector corresponding to the first network;
The receiving circuit receives the second signal using a plurality of phase vectors including the first phase vector;
When the receiving circuit receives the second signal using a second phase vector corresponding to the second network, the control circuit receives the second signal from the second network. It is determined to be a signal,
Communication device. The communication device according to claim 1 or 2,
The communication circuit is configured to stop transmission control of the first signal when the signal strength of the second signal measured by the measurement circuit is greater than a predetermined value. The communication device according to claim 1 or 2,
The control circuit is a communication device that controls transmission of the first signal when a signal strength of the second signal measured by the measurement circuit is equal to or less than a predetermined value. The communication device according to claim 3 or 4,
The control device, wherein the control circuit changes the predetermined value based on a retransmission rate of the first signal. The communication device according to claim 5,
The said control circuit is a communication apparatus which makes the said predetermined value small, when the resending rate of a said 1st signal increases. The communication device according to claim 5,
The control circuit increases the predetermined value when a retransmission rate of the first signal decreases. The communication device according to any one of claims 1 to 7,
The transmission line is a communication device including a power line. A communication method of a first communication device belonging to a first network, connectable to a transmission line to which a second communication device belonging to a second network is connected,
Receiving a second signal transmitted from the second communication device;
Measuring the signal strength of the second signal;
A communication method for transmitting or stopping transmission of the first signal based on the signal strength. The communication method according to claim 9, comprising:
Transmitting the first signal using a first phase vector corresponding to the first network;
Receiving the second signal using a plurality of phase vectors including the first phase vector;
A communication method for determining that the second signal is a signal transmitted from the second network when the second signal is received using a second phase vector corresponding to the second network. . The communication method according to claim 9 or 10, comprising:
The communication method of stopping transmission control of the first signal when the measured signal strength of the second signal is larger than a predetermined value. The communication method according to claim 9 or 10, comprising:
A communication method for controlling transmission of the first signal when the measured signal strength of the second signal is a predetermined value or less. The communication method according to claim 11 or 12,
A communication method, wherein the predetermined value is changed based on a retransmission rate of the first signal. The communication method according to claim 13, comprising:
The communication method of decreasing the predetermined value when a retransmission rate of the first signal increases. The communication method according to claim 13, comprising:
The communication method, wherein the predetermined value is increased when a retransmission rate of the first signal decreases. The communication method according to any one of claims 9 to 15,
The communication method, wherein the transmission path includes a power line.

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