JPWO2012014502A1 - COMMUNICATION METHOD, COMMUNICATION DEVICE, AND COMMUNICATION FRAME GENERATION METHOD - Google Patents

Abstract

The present invention provides a communication method, a communication apparatus, and a frame generation method for performing communication using a communication frame generated by being assigned a TM corresponding to a phase region and capable of straddling a plurality of phase regions. Objective. A communication method for transmitting a communication frame 800 using TM1 corresponding to the state of the transmission path in section A and TM2 corresponding to the state of the transmission path in section B, and transmitting a payload 803 assigned TM1 in section A Then, a pilot symbol 814 is transmitted near the boundary (t1) between the section A and the section B, and a payload 813 assigned TM2 is transmitted in the section B.

Description

  The present invention relates to a communication method, a communication apparatus, and a communication frame generation method for performing communication using communication parameters according to the state of a transmission path.

  In recent years, power line communication devices using a power line as a transmission line have been developed, and attention has been paid to increasing the communication speed and improving the reliability of communication. In communication using a power line, distortion occurs in the received signal when impulsive noise is present in the transmission path or when fluctuations in the amplitude or phase of the received signal occur due to impedance fluctuations of home appliances. As a result, bit errors in received data increase.

  In order to prevent this bit error from increasing, a method of inserting a pilot symbol for each communication frame of a transmission signal has been proposed (for example, see Patent Document 1). FIG. 16 is a diagram illustrating an example of a configuration of a communication frame in which pilot symbols are inserted.

  The communication frame of FIG. 16 shows a frame format, and one communication frame includes N symbols, and includes an information symbol including (N-1) symbols and a pilot symbol including one known symbol. One communication frame is composed of the pilot symbol and the information symbol part.

  The transmitting side transmits this communication frame, and the receiving side that receives this communication frame receives the pilot symbols, thereby estimating temporal variations in amplitude and phase of the received signal. As a result, the receiving side performs amplitude and phase fluctuation compensation with reference to the pilot symbol. Therefore, when the transmitting side inserts a pilot symbol into a communication frame and transmits the signal, the receiving side can estimate fluctuations in amplitude and phase, thereby reducing bit errors.

  In addition, the characteristics of the transmission path through which data is transmitted are not constant, and change sequentially with environmental changes and time. When the transmission line is a power line, various electric devices are connected to the power line, so that various noises appear.

  Therefore, the above-described communication method performs channel estimation (also referred to as CE: channel estimation) in order to perform communication using communication parameters corresponding to the state of the transmission path. Thereby, the state of the transmission path can be estimated, and a new communication parameter can be acquired based on the estimated result. The communication performance is improved by comparing the current communication parameter with the newly acquired communication parameter and performing communication using the communication parameter suitable for the state of the transmission path.

  Furthermore, when the transmission line is a power line, the noise tends to change with the phase of the AC waveform. For this reason, the optimal communication parameters differ with the phase of the AC waveform, and it was impossible to perform optimal communication according to the state of the transmission path with one communication parameter (except when no noise occurs in the power line).

  Therefore, a communication method for acquiring a tone map (also referred to as TM: Tone Map) suitable for a specific phase region of an AC waveform has been proposed. Thus, communication can be performed using a TM suitable for each phase of the AC waveform when data is transmitted (see, for example, Patent Document 2). TM is one of the communication parameters, and collectively holds a set of communication parameters such as the type of primary modulation applied to each subcarrier of the multicarrier signal and the type of error correction mode.

  FIG. 17 is a diagram showing an example when a plurality of TMs are acquired in one cycle of the AC waveform. FIG. 17 shows one period of the AC waveform. This AC waveform is divided into respective phase regions with time t0 to t5 as boundaries. The phase region is a region obtained by dividing the phase of a specific AC waveform by time t0 to t5. TM1 to TM5 are TMs suitable for each phase region. That is, TM1 is a TM suitable for the transmission path (AC waveform) in the phase region (t0, t1). Similarly, TM2 is a phase region (t1, t2), TM3 is a phase region (t2, t3), TM4 is a phase region (t3, t4), and TM5 is a phase region (t4, t5). TM suitable for

  For this reason, the TM assigned to the transmission data differs depending on the phase region of the AC waveform in which the transmission data is transmitted. Thereby, it is possible to always perform communication using a suitable TM.

Japanese Unexamined Patent Publication No. 2002-84332 Japanese Unexamined Patent Publication No. 2005-253076

  As described above, the communication method shown in FIG. 17 performs communication using a TM suitable for each phase region. However, the above-described communication method does not sufficiently disclose a technique for transmitting data across a plurality of phase regions. When it is desired to perform communication using a suitable TM, the transmission data needs to be transmitted in the phase region where the allocated TM is acquired. If the transmission data straddles a plurality of phase regions, there has been a problem that the transmission rate is lowered because the optimum data communication cannot be performed. Further, when transmission data is necessarily transmitted in the phase region where the assigned TM is acquired, the length of the transmission data is limited to the length of the phase region, and the timing of transmitting the transmission data is limited. . As a result, there is a problem that the transmission efficiency is lowered.

  In view of the above problems, the embodiment described below is a communication method in which transmission efficiency and transmission rate are improved by transmitting data using a plurality of communication parameters, a communication device that implements the communication method, and a communication frame generation method thereof The purpose is to provide.

  The communication method of the embodiment described below uses the first communication parameter according to the state of the transmission path in the first section and the second communication parameter according to the state of the transmission path in the second section. A communication method for transmitting a communication frame, wherein the first data to which the first communication parameter is assigned is transmitted in the first section, and a pilot is used at a boundary between the first section and the second section. Symbols are transmitted, and second data assigned with the second communication parameter is transmitted in the second interval.

  Since the communication frame is transmitted by the communication method as described above, the communication frame is transmitted across the first and second sections, and the first and second data in the communication frame are transmitted. First and second communication parameters corresponding to the state of the transmission path in the second section are assigned. That is, each data in the communication frame is assigned a communication parameter according to the section to be transmitted. In this way, since the communication frame is transmitted by switching to a suitable communication parameter in the communication frame, the communication frame can be transmitted with a length across a plurality of sections using the suitable communication parameter. Thereby, transmission efficiency and a transmission rate can be improved.

  In addition, since the pilot symbol is transmitted at the boundary between the first data and the second data, the receiving side that receives the communication frame can recognize the switching between the first communication parameter and the second communication parameter. Thereby, the receiving side can switch from reception of the first data using the first communication parameter to reception of the second data using the second communication parameter. In this way, the receiving side can receive a communication frame using a plurality of communication parameters.

External perspective view showing the front surface of the PLC modem according to the first embodiment FIG. 3 is an external perspective view showing the back surface of the PLC modem according to the first embodiment. 1 is a diagram illustrating an example of hardware of a PLC modem according to a first embodiment Functional block diagram of PLC modem in the first embodiment Functional block diagram for explaining an example of digital signal processing at the time of transmission of the PLC modem in the first embodiment Functional block diagram for explaining an example of digital signal processing at the time of reception by the PLC modem in the first embodiment The figure which shows the relationship between the AC waveform in Embodiment 1, a received signal, received noise, and a PHY speed. The figure for demonstrating the transmission-path estimation method in Embodiment 1 The figure which shows an example of allocation of the information bit to each carrier in the PLC modem of Embodiment 1 The figure which shows the communication frame produced | generated by multiple TM in Embodiment 1, and the communication frame produced | generated by single TM A flowchart showing an example of a method for determining communication parameters and a frame format in the first embodiment Flowchart illustrating an example of a communication frame generation method according to the first embodiment A flowchart showing an example of a method for determining communication parameters and a frame format in the second embodiment Functional block diagram of PLC modem in the third embodiment A flowchart showing an example of a method for determining communication parameters and a frame format in the third embodiment The figure which shows an example of a structure of the communication frame which inserted the pilot symbol. The figure which shows an example when several TM is acquired in 1 period of AC waveform The figure which shows the example from which the insertion position of the pilot symbol in Embodiment 1 differs (a), (b) is a figure which shows the various structures of the communication frame in Embodiment 4.

  The embodiment described below uses the first communication parameter according to the state of the transmission path in the first section and the second communication parameter according to the state of the transmission path in the second section. A communication method for transmitting, wherein first data to which the first communication parameter is assigned is transmitted in the first interval, and a pilot symbol is transmitted at a boundary between the first interval and the second interval. And transmitting the second data to which the second communication parameter is assigned in the second section.

  According to this communication method, the communication frame is transmitted across the first and second sections, and the first and second data in the communication frame are transmitted on the transmission paths in the first and second sections. The first and second communication parameters corresponding to the state are assigned. That is, each data in the communication frame is assigned a communication parameter according to the section to be transmitted. In this way, since the communication frame is transmitted by switching to a suitable communication parameter in the communication frame, the communication frame can be transmitted with a length across a plurality of sections using the suitable communication parameter. Thereby, transmission efficiency and a transmission rate can be improved.

  In addition, since the pilot symbol is transmitted at the boundary between the first data and the second data, the receiving side that receives the communication frame can recognize the switching between the first communication parameter and the second communication parameter. Thereby, the receiving side can switch from reception of the first data using the first communication parameter to reception of the second data using the second communication parameter. In this way, the receiving side can receive a communication frame using a plurality of communication parameters.

  The embodiment described below transmits a frame control including pilot symbol information and communication parameter information before transmitting the first data in the first interval. Regarding the method.

  According to this communication method, the frame control notifies the reception side of communication parameter information and pilot symbol information. For this reason, the receiving side can recognize whether or not a plurality of communication parameters are used in the communication frame and whether or not pilot symbols are inserted. In other words, the receiving side can recognize the frame format of the communication frame from the frame control.

  Further, in the embodiment described below, before transmitting the frame control, the configuration of the communication frame to be transmitted including the frame control, the pilot symbol, the first data, and the second data is determined. The communication frame is transmitted based on a configuration of the communication frame.

  According to this communication method, by determining the configuration of the communication frame scheduled to be transmitted, it is possible to transmit the communication frame based on it.

  In the embodiment described below, the configuration of the communication frame is determined so that the sum of the length of the second data and the length of the pilot symbol is equal to the length of the second section. The present invention relates to a communication method.

  According to this communication method, the length of the second data is the difference between the second interval and the length of the pilot symbol. Since the pilot symbol and the second interval are known lengths between the transmission side and the reception side, the second data can also have a known length between the transmission side and the reception side.

  The embodiment described below relates to a communication method characterized in that the frame control stores information on the length of the communication frame and information on the length of the first data.

  According to this communication method, the receiving side that receives the frame control can recognize the length of the communication frame and the length of the first data. As described above, since the second data has a known length for the receiving side, the receiving side can calculate the length of the communication frame excluding the first and second data.

  In the embodiment described below, after obtaining at least one communication parameter in the first time, the communication parameter is obtained in a second time shorter than the first time. Regarding the method.

  According to this communication method, the communication parameter in each section can be acquired earlier by making the second time shorter than the first time.

  In the embodiment described below, the transmission line is a power line, and the first section and the second section are specific phase regions of an AC waveform on the power line. It relates to a communication method.

  The embodiment described below is a communication apparatus that performs communication using a communication frame that crosses a plurality of sections using communication parameters according to the state of the transmission path, and includes at least the first section and the transmission path. A section control unit for identifying the second section, a first communication parameter according to the state of the transmission path in the first section, and a second communication parameter according to the state of the transmission path in the second section. Using the communication parameter acquisition unit to be acquired, the communication parameter holding unit for storing the first communication parameter and the second communication parameter acquired by the communication parameter acquisition unit, and the first communication parameter and the second communication parameter A configuration determining unit that determines a configuration of a communication frame scheduled to be transmitted, and the first communication parameter and the second communication parameter from the communication parameter holding unit. A communication parameter control unit that reads a parameter; and first data that is assigned the first communication parameter read by the communication parameter control unit based on the configuration of the communication frame and that is transmitted to the first section, and A communication frame generation unit that generates second data to be transmitted in the second section assigned with a second communication parameter and inserts a pilot symbol between the first data and the second data; And a transmitter that transmits first data, pilot symbols, and second data.

  The embodiment described below relates to a communication apparatus including a frame control generation unit that stores pilot symbol information and communication parameter information in frame control.

  In addition, in the embodiment described below, the configuration determination unit may be configured so that the sum of the length of the second data and the length of the pilot symbol is equal to the length of the second section. The present invention relates to a communication apparatus characterized by determining a configuration.

  In the embodiment described below, the frame control generation unit stores the information on the length of the communication frame and the information on the length of the first data in the frame control. The present invention relates to a communication device.

  In the embodiment described below, the communication parameter acquisition unit acquires the communication parameter at a second time shorter than the first time after acquiring at least one communication parameter at the first time. The present invention relates to a communication device.

  In the embodiment described below, the transmission line is a power line, and the first section and the second section are specific phase regions of an AC waveform on the power line. The present invention relates to a communication device.

  Further, in the embodiment described below, the first data assigned the first communication parameter according to the state of the transmission path in the first section is transmitted in the first section, and the first section Second data in which a pilot symbol is transmitted at a boundary between a section and a second section adjacent to the first section, and a second communication parameter according to a state of a transmission path in the second section is assigned. Is transmitted in the second period, and at least the first data, the pilot symbol, and the second data are transmitted to generate a communication frame.

  Also, the embodiment described below relates to a communication frame generation method characterized by transmitting a frame control including pilot symbol information and communication parameter information before transmitting the first data.

  The embodiment described below relates to a communication frame generation method characterized in that the frame control includes information on the length of the first data and information on the length of the communication frame.

  In the embodiment described below, the second data is generated so as to be equal to the difference between the length of the second section and the length of the pilot symbol. The present invention relates to a frame generation method.

(Embodiment 1)
Hereinafter, a communication method, a communication apparatus, and a communication frame generation method according to Embodiment 1 will be described with reference to the drawings.

  FIG. 1 is an external perspective view showing the front of a PLC (Power Line Communication) modem 100 as an example of a power line communication apparatus, and FIG. 2 is an external perspective view showing the back of the PLC modem 100. The PLC modem 100 shown in FIGS. 1 and 2 has a casing 101, and a display unit 105 such as an LED (Light Emitting Diode) is provided on the front surface of the casing 101 as shown in FIG. Yes.

  Further, on the rear surface of the housing 101, as shown in FIG. 2, a power connector 102, a modular jack 103 for LAN (Local Area Network) such as RJ45, and switching for switching operation modes (master mode / slave mode). A switch 104 is provided.

  A button 106 is provided on the top surface of the housing. The button 106 has a function as a setup button for starting processing (registration processing) for making the PLC modem 100 communicable. In addition, although it provided in the upper surface of the housing | casing 101 as an example, it is not restricted to this position.

  A power cable (not shown) is connected to the power connector 102, and a LAN cable (not shown) is connected to the modular jack 103. The PLC modem 100 may further be provided with a Dsub (D-subminiature) connector to connect a Dsub cable.

  Although the PLC modem 100 is shown as an example of the power line communication device, the power line communication device may be an electric device with a built-in PLC modem. As the electric equipment, for example, home appliances such as a television, a telephone, a video deck, and a set top box, office equipment such as a personal computer, a fax, and a printer, a power meter, a gas meter, and the like may be used. Furthermore, an electric device that performs communication using a coaxial cable using a DC waveform may be used.

  The PLC modem 100 is connected to the power line 700 and constitutes a power line communication system together with other PLC modems 100.

  Next, FIG. 3 mainly shows an example of the hardware configuration of the PLC modem 100. The PLC modem 100 includes a circuit module 200 and a switching power supply 300. The switching power supply 300 supplies various voltages (for example, + 1.2V, + 3.3V, + 12V) to the circuit module 200, and includes, for example, a switching transformer and a DC-DC converter (none of which are shown). Consists of.

  The circuit module 200 includes a main IC (Integrated Circuit) 210, an AFE IC (Analog Front End Integrated Circuit) 220, an Ethernet (registered trademark) PHY IC (Physical layer Integrated Circuit) 230, a memory, and a memory 240. LPF) 251, driver IC 252, band pass filter (BPF) 260, coupler 270, AMP (amplifier) IC 281, ADC (AD conversion) IC 282, and AC cycle detector 60 are provided. The switching power supply 300 and the coupler 270 are connected to the power connector 102 and further connected to the power line 700 through the power cable 600, the power plug 400, and the outlet 500. The main IC 210 functions as a control circuit that performs power line communication.

  The main IC 210 includes a CPU (Central Processing Unit) 211, a PLC / MAC (Power Line Communication / Media Access Control Layer) block 212, and a PLC / PHY (Power Line Communication / Physical Layer) block 213.

  The CPU 211 has a 32-bit RISC (Reduced Instruction Set Computer) processor. The PLC / MAC block 212 manages a MAC layer (Media Access Control layer) of transmission / reception signals, and the PLC / PHY block 213 manages a PHY layer (Physical layer) of transmission / reception signals.

  The AFE / IC 220 includes a DA converter (DAC; D / A Converter) 221, an AD converter (ADC; A / D Converter) 222, and a variable amplifier (VGA; Variable Gain Amplifier) 223. The coupler 270 includes a coil transformer 271 and coupling capacitors 272a and 272b.

  The CPU 211 uses the data stored in the memory 240 to control the operation of the PLC / MAC block 212 and the PLC / PHY block 213, and also controls the entire PLC modem 100.

  Communication by the PLC modem 100 is generally performed as follows. Data input from the modular jack 103 is sent to the main IC 210 via the Ethernet (registered trademark) PHY IC 230, and a digital transmission signal is generated by performing digital signal processing. The generated digital transmission signal is converted into an analog signal by the DA converter (DAC) 221 of the AFE / IC 220, and the low-pass filter 251, the driver IC 252, the coupler 270, the power connector 102, the power cable 600, the power plug 400, and the outlet 500. Is output to the power line 700.

  A signal received from the power line 700 is sent to the band pass filter 260 via the coupler 270, and after gain adjustment is performed by the variable amplifier (VGA) 223 of the AFE / IC 220, the signal is digitally converted by the AD converter (ADC) 222. Converted to a signal. The converted digital signal is sent to the main IC 210 and converted into digital data by performing digital signal processing. The converted digital data is output from the modular jack 103 via the Ethernet (registered trademark) PHY IC 230.

  The AC cycle detector 60 provided in the circuit module 200 generates a synchronization signal necessary for a plurality of PLC modems 100 communicating with each other to perform control at a common timing. That is, the AC cycle detector 60 generates a signal synchronized with the AC power supply waveform supplied to the power line 700.

  The AC cycle detector 60 includes a diode bridge 60a, resistors 60b and 60c, a DC power supply unit 60e, and a buffer 60d. The output of the diode bridge 60a is connected to the resistor 60b. The resistor 60b and the resistor 60c are connected in series. Resistors 60b and 60c are connected in parallel to one terminal of buffer 60d. The DC power supply unit 60e is connected to the other terminal of the buffer 60d.

  Specifically, the AC cycle detector 60 operates as follows. That is, a commercial AC power supply waveform AC supplied to the power line 700, that is, a zero cross point of an AC waveform composed of a sine wave of 50 Hz or 60 Hz is detected, and a synchronization signal based on this timing is generated. As a specific example of the synchronization signal, a rectangular wave composed of a plurality of pulses synchronized with the zero cross point of the AC power supply waveform is used. Since this signal is used to determine the phase of the AC power supply waveform in the following, it can be replaced with a circuit that detects an arbitrary voltage of the AC power supply.

  Next, an example of digital signal processing realized by the main IC 210 will be described. The PLC modem 100 uses a multicarrier signal such as an OFDM (Orthogonal Frequency Division Multiplexing) signal generated by using a plurality of subcarriers as a signal for transmission. The PLC modem 100 converts the data to be transmitted into a multicarrier transmission signal such as an OFDM signal and outputs it, and processes the multicarrier reception signal such as an OFDM signal to convert it into reception data. Digital signal processing for these conversions is mainly performed by the PLC / PHY block 213.

  Next, an example of digital signal processing at the time of transmission and reception by the PLC modem 100 in the present embodiment will be described with reference to the drawings. 4 is a functional block diagram of the PLC modem 100 according to the first embodiment, FIG. 5 is a functional block diagram for explaining an example of digital signal processing on the transmission side of the PLC modem 100 according to the first embodiment, and FIG. 3 is a functional block diagram for explaining an example of digital signal processing on the receiving side of PLC modem 100 according to Embodiment 1. FIG.

  The PLC modem 100 illustrated in FIG. 4 includes a communication parameter setting unit 11, a communication performance acquisition unit 12, a comparison unit 13, and a communication unit 14. As shown in FIG. 4, a communication parameter setting unit 11 for a block for determining communication parameters, a communication performance acquisition unit 12 for a block for acquiring communication performance information, and a block comparison unit 13 for comparing the superiority and inferiority of communication parameters, This is a functional block included in the CPU 211. The communication unit 14 of the block that actually communicates with the communication parameter determined by the communication parameter setting unit 11 is a functional block included in the PLC / MAC block 212 and the PLC / PHY block 213.

  When the communication unit 14 actually communicates with another PLC modem 100, the communication performance acquisition unit 12 can acquire communication performance information. As specific examples of communication performance, the frequency of occurrence of retransmission (hereinafter also referred to as a retransmission rate), the transmission rate (including the amount of data information per unit time, for example, the number of packets, etc.), etc. can be considered.

  A specific example of the communication parameter is, for example, a TM (Tone Map) described later. The TM is stored in the main IC 210 or the memory 240, for example, and is used for primary modulation applied to each subcarrier of the multicarrier signal. A set of communication parameters such as type and error correction mode type are stored together.

  For example, the comparison unit 13 compares the superiority of the newly acquired TM with the current TM. The current TM is a TM that has already been acquired and is stored in the main IC 210 or the memory 240. Note that TM is acquired by transmission path estimation described later.

  The superiority or inferiority of TM is determined based on the result of the communication unit 14 actually communicating with another PLC modem 100. For example, the superiority or inferiority determination method includes a transmission rate, a retransmission rate, an error rate, and the like, and the comparison unit 13 acquires the information from the communication performance acquisition unit 12. Thereby, the comparison unit 13 compares the communication performances of different TMs. In addition, the object which determines the superiority or inferiority of the comparison unit 13 is not limited to the newly acquired TM and the current TM. Different examples will be described later.

  The communication parameter setting unit 11 determines an optimal communication parameter based on the comparison result of the comparison unit 13. In the communication parameter setting unit 11, one TM is set during normal communication.

  The communication unit 14 performs communication with another PLC modem 100 connected to the common power line 700 using a modulation method or the like according to the communication parameter determined by the communication parameter setting unit 11.

  Next, digital signal processing at the time of transmission by the transmitting PLC modem 100A will be described with reference to the functional block diagram of FIG. A detailed description of the preamble, frame control, payload, and pilot symbol will be described later with reference to FIG.

  A transmitting-side PLC modem 100A shown in FIG. 5 includes an encoding unit 21, a primary modulation unit 22, a frame generation unit 23, an inverse wavelet conversion unit 24, an AC zero cross detection unit 25, a phase domain control unit 26, and pilot symbol insertion. A control unit 27, a modulation TM control unit 28, an FC generation unit 29, and an analog unit (AFE / IC) 220 are provided.

  The encoding unit 21 generates bit data by encoding input data with a predetermined error correction code. The input data includes data to be transmitted (payload) and frame control. The primary modulation unit 22 performs primary modulation (for example, PAM modulation) on the bit data to be transmitted from the encoding unit 21 in accordance with the primary modulation method for each carrier stored in the TM.

  The frame generation unit 23 generates a communication frame of a predetermined format based on serial data subjected to primary modulation (symbol mapping), and further converts it into parallel data. The frame generation unit 23 generates a communication frame using the payload modulated by the primary modulation unit 22, the primary modulated frame control, the preamble that is a known signal, and the pilot symbol that is a known signal (described later). To do. The payload and frame control are converted into parallel data, the preamble is read at a transmission timing described later, and a pilot symbol is inserted into the communication frame at a timing notified by the pilot symbol insertion control unit 27. The preamble and pilot symbol are known signals, and for example, those stored in the memory 240 or the main IC 210 are used.

  The inverse wavelet transform unit 24 performs inverse wavelet transform on the parallel data from the frame generation unit 23 to obtain data on the time axis, and generates a sample value series representing a transmission symbol. This data is sent to the DA converter (DAC) 221 of the analog unit (AFE / IC) 220.

  The AC zero cross detector 25 detects the zero cross point of the AC waveform detected by the analog unit (AFE / IC) 220. The phase region control unit 26 has a counter function and virtually identifies an AC waveform into a plurality of phase regions (sections). From the zero cross point of the AC waveform detected by the AC zero cross detection unit 25, the phase region control unit 26 counts for a certain time to determine one phase region of the AC waveform. By repeating this, one cycle of the AC waveform is identified at regular intervals, for example, in 16 phase regions. The phase region control unit 26 can distinguish the phase region of the AC waveform by assigning a code (for example, a number) to each identified phase region. Further, the phase domain control unit 26 notifies the pilot symbol insertion control unit 27 and the modulation TM control unit 28 of the timing for switching the phase domain.

  The pilot symbol insertion control unit 27 notifies the frame generation unit 23 of the pilot symbol insertion timing based on the phase region change timing notified from the phase region control unit 26. At this timing, the frame generation unit 23 inserts a pilot symbol into the communication frame to be generated. Details will be described later with reference to FIG.

  The modulation TM control unit 28 controls the encoding unit 21 and the primary modulation unit 22 based on TM acquired by transmission path estimation described later. The encoder 21 is notified of error correction code information, and the primary modulator 22 is notified of the number of bits to be put in each carrier. Thereby, the encoding part 21 and the primary modulation part 22 can reflect the TM information acquired by the transmission path estimation. When a plurality of TMs are used for one communication frame, the TMs are switched at the timing when the phase region notified from the phase region control unit 26 changes. Details will be described later with reference to FIG.

  The FC generation unit 29 stores information necessary for transmission / reception of the communication frame in the frame control. For example, control information such as a transmission source address, a transmission destination address, and a payload format is stored. Further, ON / OFF of a pilot symbol flag to be described later, ON / OFF of a plurality of TM flags, the first TM number of the communication frame, the number of symbols of the first payload (first payload length), the number of symbols of the entire communication frame (communication The frame length) is also stored in the frame control.

  Next, digital signal processing at the time of reception by the receiving PLC modem 100B will be described with reference to the functional block diagram of FIG.

  The functional block diagram at the time of reception of the receiving side PLC modem 100B shown in FIG. 6 is a wavelet transform unit (Wavelet) 31, a data extraction unit 32, a transmission path estimation unit 33, a TM determination unit 34, a data determination unit 35, and a decoding unit. 36, a plurality of TM parameter extraction unit 37, an AC timing control unit 38, a demodulation TM control unit 39, a pilot symbol control unit 40, and an analog unit (AFE / IC) 220.

  The wavelet transform unit 31 performs discrete wavelet transform on the frequency axis of received digital data (sample value series sampled at the same sample rate as that at the time of transmission) obtained from the AD converter (ADC) 222 of the AFE / IC 220. is there.

  The data extraction unit 32 converts parallel data on the frequency axis into serial data, and extracts valid data (a payload excluding frame control and pilot symbols) from the converted data. In extracting effective data, a control signal from the pilot symbol control unit 40 is used. The data determination unit 35 calculates the amplitude value of each subcarrier, determines the reception signal, and obtains reception data.

  The decoding unit 36 performs error correction processing on the received data, and obtains decoded frame control and payload. The obtained frame control is sent to the multiple TM parameter extraction unit 37 and used for data extraction by the data extraction unit 32. For example, the payload extraction process of the data extraction unit 32 is changed according to whether the pilot symbol flag is ON or OFF.

  The multiple TM parameter extraction unit 37 extracts information necessary for reception stored in the frame control. For example, ON / OFF of a pilot symbol flag to be described later, ON / OFF of a plurality of TM flags, the first TM number of the communication frame, the number of symbols of the first payload (first payload length), the number of symbols of the entire communication frame (communication Frame length of the entire frame).

  The AC timing control unit 38 grasps various switching in the received communication frame from the information extracted from the frame control by the multiple TM parameter extraction unit 37. For example, the TM switching timing is notified to the demodulation TM control unit 39, and the pilot symbol control unit 40 is notified of the timing at which the pilot symbol is inserted into the communication frame.

  The demodulation TM control unit 39 switches the TM based on the notification from the AC timing control unit 38 (details will be described later). Further, the TM stored in the main IC 210 or the memory 240 is read from the TM number notified from the multiple TM parameter extraction unit 37. Thus, the demodulation TM control unit 39 notifies the data determination unit 35 of information on the number of bits of each carrier, and notifies the decoding unit 36 of information on the error correction code. Based on this information, the data determination unit 35 determines the amplitude value of each subcarrier, and the decoding unit 36 performs error correction processing. Thereby, the payload is demodulated.

  The pilot symbol control unit 40 notifies the data extraction unit 32 of the timing at which the pilot symbol of the received communication frame is inserted. Thereby, the data extraction unit 32 extracts the payload according to the timing at which the pilot symbol is inserted.

  The transmission path estimation unit 33 and the TM determination unit 34 will be described in detail in transmission path estimation described later.

  As described above, the PLC / PHY block 213 of the main IC 210 performs various digital signal processing to generate a transmission signal and extract a reception signal. However, the main IC 210 acquires a transmission path state. A function as an acquisition unit, a function as a communication parameter acquisition unit that acquires communication parameters based on the state of the transmission path, and a function as a communication frame determination unit that determines the communication parameters used for communication and the frame format of the communication frame Play.

  Next, transmission path estimation of PLC modem 100 in the present embodiment will be described in detail with reference to FIGS. 7 is a diagram showing the relationship between the AC waveform, the received signal, the received noise, and the PHY speed in the first embodiment, FIG. 8 is a diagram for explaining the transmission path estimation method in the first embodiment, and FIG. It is a figure which shows an example of allocation of the information bit to each carrier in the PLC modem 100 of form 1.

  FIG. 7 divides one period of the AC waveform of the power flowing through the power line serving as the transmission line of the PLC modem 100 into phase regions (sections) A to P having time t0 to 16 as boundaries, and the divided equal phase phases. It is the figure which allocated the suitable PHY speed | rate to area | region AP. This PHY speed is determined according to the state of the transmission path, that is, according to reception noise and transmission path fluctuation. Received noise is noise that is seen in received data and tends to be seen in synchronization with the period of the AC waveform, and often occurs largely near the zero cross of the AC waveform. FIG. 7 shows an example when reception noise is observed in synchronization with the AC waveform. Here, reception noise is large in the vicinity of the phase regions A to C and I to K. The received signal is a power line communication signal (hereinafter also referred to as a PLC signal) transmitted from another PLC modem 100 via a power line as a transmission path. When this PLC signal is transmitted to the power line, the amplitude and phase of the PLC signal may vary depending on the characteristics of the power line. Such a variation often occurs with a variation in impedance (Z) related to the power line (hereinafter also referred to as Z variation), which causes a transmission error. For this reason, FIG. 7 shows an example when transmission path fluctuations are observed in synchronization with the AC waveform. Here, transmission path fluctuations are seen in the phase regions D, E, L, and M. In the phase regions D and L, the received signal decreases rapidly, and in the phase regions E and M, the received signal increases rapidly.

  In order to perform communication according to the transmission line noise and the state of the transmission line fluctuation as described above, channel estimation (also referred to as CE: Channel Estimation, transmission path estimation) is performed. By performing the transmission path estimation, a TM corresponding to the transmission path status can be acquired. The transmission side PLC modem 100A is the data transmission side, and the reception side PLC modem 100B is the data reception side. The transmission path estimation will be described in detail below.

  The communication unit 14 of the transmitting PLC modem 100A transmits a CE signal to the receiving PLC modem 100B. The CE signal includes a known signal that is recognized in advance between the transmitting PLC modem 100A and the receiving PLC modem 100B. When the communication unit 14 of the receiving PLC modem 100B receives the CE signal, the transmission path estimation unit 33 evaluates a known signal included in the CE signal, and performs CINR (Carrier to Interference and Noise Ratio) for each subcarrier of the multicarrier. , Carrier power to (interference wave + noise) power ratio).

  Here, an example of the operation of the transmission path estimation unit 33 will be described with reference to FIG. The transmission path estimation unit 33 calculates an error between the known signal (+1 or −1) included in the CE signal and the received signal. Further, the mean square of this error is calculated, and this calculated value becomes the average noise amount. This operation is performed for each subcarrier, and the CINR for each subcarrier is calculated. Based on this CINR, the TM determination unit 34 determines the TM.

  Here, an example of a TM determination method will be described with reference to FIG. FIG. 9A shows CINR for each frequency (subcarrier), and FIG. 9B shows the number of bits allocated corresponding to this CINR. As described above, the transmission path estimation unit 33 calculates the CINR shown in FIG. 9A from the known signal included in the received CE signal. Based on this CINR, the TM determination unit 34 allocates information bits in association with the CINR for each subcarrier as shown in FIG. 9B. Thereby, the TM determination unit 34 calculates a set of communication parameters such as the type of primary modulation and the type of error correction mode to be applied to each subcarrier, and determines a TM to hold these together.

  The TM determined as described above is stored in a CER (Channel Estimate Response) signal. The receiving PLC modem 100B sends this CER signal back to the transmitting PLC modem 100A, whereby the transmitting PLC modem 100A acquires TM. The transmitting-side PLC modem 100A stores the TM stored in the CER signal in the memory 240 or the main IC 210 that also functions as a communication parameter holding unit. Note that TM is acquired for each transmission destination. For example, when the receiving PLC modems C and D exist in addition to the receiving PLC modem B, the transmitting PLC modem 100A performs transmission path estimation for the receiving PLC modems B to D, respectively, and acquires TM.

  The TM determining unit 34 of the receiving PLC modem 100B adds a code (here, a number) to the determined TM and stores it in the main IC or the memory 240 of the receiving PLC modem 100B. Thereby, TM can be shared between the transmission side PLC modem 100A and the reception side PLC modem 100B. Therefore, the receiving side PLC modem 100B can read the TM only by being notified of the TM number. Needless to say, alphabets or kana that have been subjected to code conversion may be used as codes other than numbers.

  Further, TM is acquired for each of the phase regions A to P. For example, the transmitting-side PLC modem 100A acquires a TM corresponding to the state of the transmission path in the phase region A by transmitting the CE signal in the phase region A. That is, in order to acquire TMs in all the phase regions A to P, at least 16 transmission path estimations are required. Furthermore, the code given to TM has regularity corresponding to the phase region. For example, the TM acquired in the phase region A is TM1, and the TM acquired in the phase region B is TM2. Thus, consecutive numbers are assigned to TMs acquired in adjacent phase regions. In addition, a gray code or the like may be used.

  The frame generation unit 23 generates a communication frame using the TM determined as described above. Hereinafter, three frame formats will be described with reference to FIG. The two frame formats use only one TM in a communication frame (hereinafter also referred to as a single TM), and the other frame format uses a plurality of TMs in one communication frame (hereinafter referred to as a single TM). , Also described as multiple TMs). FIG. 10 is a diagram showing communication frames generated by a plurality of TMs and communication frames generated by a single TM in the first embodiment.

  Further, FIG. 10 assumes the phase regions A to D of the AC waveform of FIG. 7, and it is assumed that a communication frame is generated in these phase regions (sections) A to D. In other words, the communication frame is generated across the phase regions (sections) A to D. Here, only the configuration of the communication frame and its characteristics will be described, and the details of the generation procedure will be described later.

  A single TM communication frame 840 includes a preamble (PR) 841, a frame control (FC) 842, and a payload (PLD: Payload) 843. The payload 843 is assigned TM0.

  A single TM communication frame 850 is composed of a preamble 851, a frame control 852, a payload 853, and a pilot symbol (PLT: Pilot Symbol) 854, and the payload 853 is assigned TM0.

  A communication frame 800 using multiple TMs includes a preamble 801, a frame control 802, payloads 803, 813, 823, and 833, and pilot symbols 814, 824, and 834. The payload 803 is TM1, the payload 813 is TM2, and the payload 823 is TM3 and TM4 are assigned to the payload 833, respectively.

  Preambles 801, 841, and 851 store data used for symbol synchronization, equalization coefficient calculation, and the like. The frame controls 802, 842, and 852 store control information such as a transmission source address, a transmission destination address, and a payload format.

  Further, the frame controls 802, 842, and 852 include information on pilot symbol flags (ON / OFF) and multiple TM flags (ON / OFF), and notify the receiving side PLC modem 100B of the frame format. Therefore, the frame control 842 of the communication frame 840 includes information on the pilot symbol flag (OFF) and the multiple TM flag (OFF), and the frame control 852 of the communication frame 850 includes the pilot symbol flag (ON) and the multiple TM flag (OFF). The frame control 802 of the communication frame 800 includes information on a pilot symbol flag (ON) and a plurality of TM flags (ON).

  Payloads 803, 813, 823, 833, 843, and 853 are data to be transmitted, that is, store part or all of the data that is originally desired to be transmitted.

  Pilot symbols 814, 824, 834, and 854 are known signals, and are generally periodically inserted into a communication frame. Thus, for example, the receiving PLC modem 100B that receives the communication frame 850 newly estimates the state of the transmission path by monitoring the phase and amplitude of the received signal in the pilot symbol 854 section. For this reason, the receiving-side PLC modem 100B can equalize the received signal based on the newly estimated state of the transmission path, and can follow the fluctuation of the transmission path. Thereby, an increase in bit errors can be reduced.

  For this reason, if transmission path fluctuation exists in the phase region B, the receiving PLC modem 100B is affected by the transmission path fluctuation when receiving the payload 813, but can compensate the transmission path fluctuation in the pilot symbol 824 section. Therefore, the receiving-side PLC modem 100B can reduce bit errors in the phase regions C and D, and can reduce the retransmission rate. Therefore, the receiving-side PLC modem 100B can cope with transmission line fluctuations in a timely manner.

  TM0 is a TM acquired by the above-described transmission path estimation. When a communication frame is generated by a single TM, basically, only one TM corresponding to the transmission destination is stored in the main IC 210 or the memory 240 (when a plurality of TMs are stored). A communication frame based on a single TM may be generated. The TM at this time is set as the base TM0, and the base TM0 is assigned to the payload existing in all the phase regions AP.

  In addition, pilot symbols 854 are periodically inserted into the communication frame 850. Here, in this embodiment, pilot symbols 854 are inserted into communication frame 850 every 128 symbols. Accordingly, the payload 853 is 128 symbols. The symbol is not particularly limited to 128 symbols, and may be 64 symbols, 256 symbols, or 100 symbols.

  Further, in the case of a communication frame 840 based on a single TM, since the pilot symbol 854 is not inserted, the proportion of payload that is valid data can be increased. Therefore, for example, when the state of the transmission path in the phase regions A to D is good, it is desirable to perform communication using the communication frame 840 using a single TM. Thereby, transmission efficiency can be improved.

  Next, the communication frame 800 using a plurality of TMs will be described in detail. The communication frame 800 is assigned a plurality of TM1-4. TM1 to TM4 are TMs determined according to the state of the transmission paths in the phase regions A to D by the transmission path estimation. More specifically, TM1 is a TM according to the state of the transmission line in the phase region A, TM2 is a TM according to the state of the transmission line in the phase region B, and TM3 is a state of the transmission line in the phase region C. TM4 is a TM according to the state of the transmission path in the phase region D.

  Accordingly, the payload 803 existing in the phase region A is assigned TM1, the payload 813 existing in the phase region B is assigned TM2, and the payload 823 existing in the phase region C is assigned TM3 and exists in the phase region D. Payload 833 is assigned TM4.

  Thereby, the communication frame 800 is generated using TM corresponding to each phase region A to D of the AC waveform to be transmitted. Therefore, data transmission can be performed using a modulation method with a transmission rate suitable for the state of the transmission path in each of the phase regions A to D and a modulation method with few errors. Details of acquiring a plurality of TMs will be described later.

  Pilot symbols 814, 824, and 834 are inserted at the boundaries where the phase regions are switched. The pilot symbol inserted at the boundary here is any one of pilot symbols inserted in the vicinity of times t1 to t3 in the five communication frames shown in FIG. FIG. 18 is a diagram illustrating an example in which pilot symbol insertion positions are different in the first embodiment. The receiving PLC modem 100B that receives the communication frame 800 can recognize the TM switching in the communication frame 800 by receiving the pilot symbols 814, 824, and 834. That is, for example, the pilot symbol 814 has a role of notifying the receiving side PLC modem 100B of the switching timing between TM1 and TM2. Thereby, the receiving-side PLC modem 100B can recognize the switching timing between TM1 and TM2. Further, it is preferable that the middle-stage payloads 813 and 823 have the same number of symbols (the reason will be described later).

  As described above, the communication frame 800 is switched to a suitable TM in the communication frame 800 and transmitted. For this reason, even if the communication frame 800 is transmitted across the phase regions A to D, it is always transmitted using TM1 to TM4 suitable for the phase regions A to D. Further, the transmitting PLC modem 100A does not have to limit the length of one communication frame within one phase region in order to use a suitable TM. If one communication frame is transmitted in each phase region A to D, the transmitting PLC modem 100A transmits the preamble and frame control in each phase region A to D, and the receiving PLC modem 100B transmits a communication frame. ACK (reception response signal) is sent back to the transmitting-side PLC modem 100A each time the signal is received, and the overhead that is a portion (time) that is not valid data in the traffic (band) on the transmission path increases. However, since the communication frame 800 is transmitted across the phase regions A to D, this increase in overhead can be reduced. Furthermore, since the communication frame 800 is switched to a suitable TM according to the phase region to be transmitted, the transmission rate can be improved.

  Next, a method for determining communication parameters and frame format of transmitting side PLC modem 100A in the present embodiment will be described with reference to the drawings. FIG. 11 is a flowchart illustrating an example of a method for determining communication parameters and a frame format in the first embodiment.

  The determination of the frame format in the present embodiment is to determine which one of the three frame formats shown in FIG. 10 described above is used. For example, a single TM is used as in the communication frame 840 (only the base TM0 is used), and when no pilot symbol is inserted, the frame format is set to a plurality of TMs (OFF) and pilots (OFF). In addition, a single TM is used (only the base TM0 is used) as in the communication frame 850, and when a pilot symbol is inserted, the frame format is set to a plurality of TMs (OFF) and pilots (OFF). In addition, a plurality of TMs are used as in the communication frame 800, and when inserting pilot symbols, the frame format is set to a plurality of TMs (ON) and pilots (ON).

  The determination of the communication parameter in the present embodiment is the determination of the TM used when performing communication. For example, when the frame format is a plurality of TMs (OFF), the base TM0 is determined. Further, when the frame format is a plurality of TM (ON), a specific TM in each phase region is determined.

  Further, the side that transmits data will be described as a transmitting side PLC modem 100A, and the side that receives the data will be described as a receiving side PLC modem 100B. That is, the transmission-side PLC modem 100A uses the functional block of FIG. 5, and the reception-side PLC modem 100B uses the functional block of FIG. Hereinafter, according to the flowchart of FIG. 11, a series of flows of the communication parameter and frame format determination method will be described.

  In step S101, the CPU 211 of the transmitting PLC modem 100A confirms the current frame format. Temporarily, when the transmitting PLC modem 100A communicates with the receiving PLC modem 100B for the first time, the frame format is in the initial state, and therefore, there are a plurality of TMs (OFF) and pilots (OFF). When the frame format is pilot (ON), the process proceeds to step S113, and when it is pilot (OFF), the process proceeds to step S102.

  In step S102, the transmitting-side PLC modem 100A acquires a new TM (hereinafter also referred to as a new TM) without recognizing in which phase region the above-described transmission path estimation (CE) is performed. That is, the transmitting PLC modem 100A transmits the CE signal to the receiving PLC modem 100B without recognizing which phase region of the AC waveform. For this reason, the transmitting-side PLC modem 100A does not identify the phase region of the transmission path in which the CER signal sent back from the receiving-side PLC modem 100B is TM. Therefore, the transmitting-side PLC modem 100A acquires a new TM without identifying which phase region is suitable for the state of the transmission path. The acquired new TM is stored in the main IC 210 or the memory 240. The CE signal in the transmission path estimation here does not recognize the phase region in which it is transmitted, so the AC zero cross detection unit 25 and the phase region control unit 26 do not have to perform digital signal processing. Thereby, the transmitting-side PLC modem 100A can simply acquire a new TM.

  In step S103, the CPU 211 of the transmitting PLC modem 100A confirms whether the current TM is stored in the main IC 210 or the memory 240. The main IC 210 or the memory 240 normally stores the current TM. However, if the transmission side PLC modem 100A has not yet performed transmission path estimation with the receiving side PLC modem 100B, the current TM is naturally not stored. If the current TM is stored, the process proceeds to step S104. On the other hand, when the current TM is not stored, the process proceeds to step S108.

  In step S104, training (speed comparison) is performed between the current TM stored in the main IC 210 or the memory 240 and the new TM acquired in step S102. Training means that data is actually transmitted using different communication parameters, and the comparison unit 13 compares the superiority and inferiority of the communication parameters based on the result of the transmission speed. The training target here uses the current TM, and when the frame format is multiple TM (OFF) and pilot (OFF) (hereinafter also referred to as the current TM pilot (OFF)), and uses the new TM. This is a case where the frame format is a plurality of TMs (OFF) and pilots (OFF) (hereinafter also referred to as new TM pilots (OFF)). The communication unit 14 of the transmission side PLC modem 100A actually sends the current TM pilot (OFF) and the new TM pilot (OFF) to the reception side PLC modem 100B, and the reception side PLC modem 100B transmits two signals to the transmission side PLC modem 100A. Send back the transmission rate information. Thereby, the communication performance acquisition unit 12 acquires the transmission rate information. Further, the comparison unit 13 compares the superiority and inferiority of the current TM pilot (OFF) and the new TM pilot (OFF) based on this transmission rate information, and the one with the superior transmission rate is the winner of training. Note that this transmission rate information may be returned as a single unit, but it is preferable to return the transmission rate information by including it in the ACK because the traffic deterioration can be suppressed.

  The transmission rate here is calculated by the product of the PHY rate and (1-retransmission rate). The PHY speed can be calculated from the communication parameters at this time. Here, the PHY rate is PHY rate = (sum of information bits allocated to each carrier) × error correction coding rate / symbol length. Further, the MAC speed may be used as the transmission speed to be compared. The MAC speed is MAC speed = PHY speed × (1−retransmission rate) × conversion efficiency. Here, the conversion efficiency is conversion efficiency = payload length / (preamble length + frame control length + payload length + gap section length). The conversion efficiency when pilot symbols are inserted is: conversion efficiency = payload length / (preamble length + frame control length + payload length + gap interval length + pilot symbol length) It is.

  In step S105, the transmitting-side PLC modem 100A determines the course by the winner of the training in step S104. When the current TM pilot (OFF) is a winner, the process proceeds to step S106, and when the new TM pilot (OFF) is a winner, the process proceeds to step S108.

  In step S106, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines a communication parameter. Since the winner of the training in step S106 is the current TM, the communication parameter setting unit 11 sets the current TM to the base TM0.

  In step S107, the transmitting-side PLC modem 100A performs training (speed comparison) between the current TM pilot (ON) and the current TM pilot (OFF).

  In step S108, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines a communication parameter. Since the winner of the training in step 104 is the new TM, the communication parameter setting unit 11 sets the new TM as the base TM0. If the current TM is not stored in the first place, the new TM acquired in step S102 is set as the base TM0.

  In step S109, the transmitting-side PLC modem 100A performs training (speed comparison) between the new TM pilot (ON) and the new TM pilot (OFF).

  In step S110, the transmitting-side PLC modem 100A determines the course based on the frame format of the training winner in steps S107 and S109. When the training winner at step S107 is the current TM pilot (ON) or when the training winner at step S109 is the new TM pilot (ON), the course proceeds to step S111. When the training winner at step S107 is the current TM pilot (OFF) or when the training winner at step S109 is the new TM pilot (OFF), the course proceeds to step S112.

  In step S111, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines the frame format. As a result of the training in step S107 and step S109, the pilot (ON) transmission rate was superior, so the frame format is pilot (ON) and multiple TMs (OFF).

  In step S112, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines the frame format. As a result of the training in step S107 and step S109, the pilot (OFF) transmission rate was superior, so the frame format is pilot (OFF) and multiple TMs (OFF).

  In step S113, the transmitting-side PLC modem 100A acquires a new TM specific to one phase region among the plurality of phase regions. The AC zero-cross detection unit 25 detects a zero-cross point of the AC waveform, and the phase region control unit 26 equally divides the AC waveform into a plurality of (16 here) phase regions A to P from the zero-cross point, thereby obtaining a plurality of phases. Regions A to P are identified. Thus, the transmission side PLC modem 100A recognizes in which phase region (phase) of the AC waveform the transmission is performed, and sends the CE signal to the reception side PLC modem 100B. Acquire a new TM according to the state. The acquired new TM is stored in the main IC 210 or the memory 240. Although the phase region is equally divided here, it may be unequally divided. The phase region where the influence of the transmission path fluctuation and noise is large is shortened, while the phase area where the influence of the transmission path fluctuation and noise is small is lengthened. As a result, the number of pilot symbols in the communication frame can be reduced and the payload ratio can be increased.

  In step S114, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines the frame format. Since a new TM specific to the phase region is acquired in step S113, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines the frame format as pilot (ON) and plural TMs (ON). At this time, the base TM0 is assigned to the payload transmitted in the phase area where the TM specific to the phase area is not acquired.

  In step S115, the transmitting-side PLC modem 100A performs training using a plurality of TMs. The training here will be described below with reference to FIG. For example, in step S113, it is assumed that transmission path estimation in the phase region D is performed and a new TM4 is acquired. At this time, assuming that the current TM4 is stored in the main IC 210 or the memory 240, the training target here is the case where the current TM4 is used when data is transmitted in the phase region D and the data is transmitted in the phase region D. In this case, the new TM4 is used. A plurality of TM (ON) communication frames including the current TM4 and a plurality of TM (ON) communication frames including the new TM4 are transmitted a plurality of times. Thereby, the comparison unit 13 averages the transmission rate information sent back from the receiving side PLC modem 100B, thereby comparing the superiority of the current TM4 and the new TM4. Note that the communication frame transmitted in this training does not necessarily include the current TM4 or the new TM4 each time. In order to perform the training fairly, the training may be performed under the same conditions except that the current TM and the new TM are different.

  In step S116, the transmitting PLC modem 100A determines the course based on the winner of the training in step S115. When the new TM is used as a winner, the process proceeds to step S117. When the new TM is not used as a winner, the process proceeds to step S118.

  In step S117, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines a communication parameter. The communication parameter setting unit 11 changes the current TM in the phase region from which the new TM has been acquired in step S113 to the new TM. That is, when transmitting data in this phase region, the new TM is used.

  In step S118, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines a communication parameter. The communication parameter setting unit 11 does not change the current TM in the phase region from which the new TM has been acquired in step S113 to the new TM. That is, when transmitting data in this phase region, the current TM is used.

  In the present embodiment, training actually sends valid data. Thereby, data transmission can be performed continuously. Accordingly, continuous communication can be performed and more TMs can be acquired by repeating the communication parameter determination flow. Thereby, communication can be performed using TM suitable for each phase region AP of the AC waveform.

  The flow for determining the communication parameter may be periodically performed at regular intervals, or may be performed before the transmission side PLC modem 100A transmits data to the reception side PLC modem 100B. Further, once the frame format becomes plural TM (ON) or pilot (ON), the period for performing the communication parameter determination flow in FIG. 11 is made shorter than when the frame format is plural TM (OFF). Also good. As a result, TMs specific to the phase region can be acquired more frequently. For this reason, characteristic TM in each phase area | region AP can be aligned earlier.

  In the present embodiment, when transmitting side PLC modem 100A estimates the transmission path in step S113, it recognizes which phase region to transmit and transmits the CE signal to receiving side PLC modem 100B. The CE signal may be transmitted by designating the phase region. For example, when the transmitting-side PLC modem 100A already holds a specific TM in the phase regions B to P other than the phase region A, the transmission timing may be adjusted so that the CE signal can be transmitted in the phase region A. (The CE signal may be transmitted by designating the phase region A). As a result, it is possible to efficiently acquire a unique TM in all the phase regions A to P.

  In the present embodiment, pilots (ON / OFF) and multiple TMs (ON / OFF) are determined by performing training. However, even if communication is always performed with pilots (ON) and multiple TMs (ON). good. The TM corresponding to any one of the phase areas A to P can be acquired by periodically performing transmission path estimation (step S113). For this reason, TM according to the state of the transmission line in each phase area | region AP can be acquired earlier.

  Next, a communication frame transmission procedure will be described with reference to FIG. The communication frame is transmitted using the communication parameters described above. FIG. 12 is a flowchart illustrating an example of a communication frame generation method according to the first embodiment.

  In step S201, the transmitting-side PLC modem 100A confirms whether or not data can be transmitted to the transmission path, and determines whether or not data can be sent to the transmission path. Thereby, the transmission timing of transmission data (communication frame) is determined. That is, the positions of the preamble and the frame control, which are the known number of symbols (known length), are determined. When a transmission line is shared as in the PLC modem 100, it is necessary to check the availability of the transmission line.

  Hereinafter, the communication frame generation procedure differs depending on the current frame format determined by the communication parameter setting unit 11.

  When the current frame format is pilot (OFF) and multiple TMs (OFF), the process proceeds to step S204. When the current frame format is pilot (ON) and multiple TMs (OFF), the process proceeds to step S208, where pilot (ON) and multiple TMs (ON) are processed. In this case, the process proceeds to step S212.

  First, the case where the process proceeds to step S204 will be described.

  In step S204, the CPU 211 calculates the number of symbols of the communication frame to be transmitted. That is, the transmitting PLC modem 100A calculates the number of symbols in the payload based on the amount of data desired to be sent to the receiving PLC modem 100B and the TM used. Since the TM holds a set of communication parameters such as the type of primary modulation and the type of error correction mode as described above, the number of symbols in the payload inevitably varies depending on the TM used even with the same amount of data. In this embodiment, the number of symbols in the communication frame is the number of symbols after frame control, and the maximum number of symbols in the communication frame (maximum frame length) is 5 msec.

  In step S205, the CPU 211 determines the configuration of the communication frame from the calculation result of the number of symbols in step S204. That is, by determining the number of symbols of the entire communication frame, the number of symbols of each payload, the TM to be assigned to each payload, the presence / absence of pilot symbol insertion, and the like, the completed form of the communication frame to be transmitted is determined. Transmission is started based on this completed form. The communication frame determined here is assumed to be the same as the communication frame 840 in FIG.

  In step S206, a preamble 841, which is a known signal, is transmitted, and then a frame control 842 generated by the FC generation unit 29 is transmitted. The frame control 842 stores control information such as a transmission source address, a transmission destination address, and a payload format. Further, the FC generation unit 29 also stores the pilot symbol flag (OFF), a plurality of TM flags (OFF), the number of symbols of the payload 843, and the like in the frame control 842.

  In step S207, the payload 843 to which the base TM0 is assigned is transmitted. The modulation TM control unit 28 notifies the information about the base TM0 to the encoding unit 21 and the primary modulation unit 22, and based on this, the encoding unit 21 and the primary modulation unit 22 modulate the payload 843. The frame generation unit 23 converts the payload 843 from serial data to parallel data. The payload 843 is transmitted to the receiving side PLC modem 100B via the inverse wavelet transform unit 24 and the analog unit 220.

  By continuously transmitting data as described above, the communication frame 840 is transmitted as one unit.

  Next, a case where the process proceeds to step S208 will be described.

  In step S208, the CPU 211 calculates the number of symbols of the communication frame to be transmitted. The calculation here is performed in consideration of the amount of data to be sent, the TM to be used, and the number of pilot symbols to be inserted. Note that the pilot symbols in this embodiment are 9 symbols.

  In step S209, the CPU 211 determines the configuration of the communication frame from the calculation result of the number of symbols in step S208. The communication frame determined here is assumed to be the same as the communication frame 850 in FIG.

  In step S210, a preamble 851, which is a known signal, is transmitted, and then a frame control 852 generated by the FC generation unit 29 is transmitted. The frame control 852 stores control information such as a transmission source address, a transmission destination address, and a payload format. Further, the FC generation unit 29 also stores the pilot symbol flag (ON), a plurality of TM flags (OFF), the number of symbols of the entire communication frame 850 (excluding the number of symbols of the preamble 851 and the frame control 852), and the like in the frame control 852.

  In step S211, payload 853 to which base TM0 is assigned and pilot symbol 854 are transmitted. Here, pilot symbols 854 are transmitted every 128 symbols. That is, the first and second payloads 853 are 128 symbols. Payload 853 is assigned base TM0. That is, the modulation TM control unit 28 notifies the information about the base TM0 to the encoding unit 21 and the primary modulation unit 22, and based on this, the encoding unit 21 and the primary modulation unit 22 modulate the payload 853. The frame generation unit 23 converts the payload 853 from serial data to parallel data. The payload 853 is transmitted to the receiving PLC modem 100B via the inverse wavelet transform unit 24 and the analog unit 220.

  Next, a case where the process proceeds to step S212 will be described.

  In step S212, the CPU 211 calculates the number of symbols of the communication frame to be transmitted. The calculation here is performed in consideration of the amount of data to be sent, the TM to be used, and the number of pilot symbols to be inserted. When a communication frame to be generated straddles a plurality of phase regions, a plurality of TMs are used.

  In step S213, the CPU 211 determines the configuration of the communication frame from the calculation result of the number of symbols in step S212. That is, the completed form of the communication frame scheduled to be transmitted is determined. For example, the number of symbols of each payload and the TM assigned to each payload are determined here, and transmission is started based on this. Therefore, the CPU 211 also has a function of a communication frame configuration determination unit. The communication frame determined here is assumed to be the same as the communication frame 800 in FIG.

  In step S214, a preamble 801 that is a known signal is transmitted, and then a frame control 802 generated by the FC generation unit 29 is transmitted. The frame control 802 stores control information such as a transmission source address, a transmission destination address, and a payload format. Further, the FC generation unit 29 performs pilot symbol flag (ON), multiple TM flags (ON), the first TM number, the number of symbols in the first payload 803, the number of symbols in the entire communication frame 800 (the symbols of the preamble 801 and the frame control 802). Etc.) are also stored in the frame control 802.

  In step S215, a payload to which a TM corresponding to the phase region to be transmitted is assigned is transmitted, and pilot symbols are transmitted by switching the phase region. That is, payload 803 assigned TM1, pilot symbol 814, payload 813 assigned TM2, pilot symbol 824, payload 823 assigned TM3, pilot symbol 834, payload 833 assigned TM4 are transmitted in this order. The Further, the modulation TM control unit 28 is notified of the timing of switching the phase region from the phase region control unit 26, thereby changing the information regarding the TM notified to the encoding unit 21 and the primary modulation unit 22. As a result, the TMs assigned to the payloads 803, 813, 823, and 833 are different.

  Next, a method for receiving a communication frame 800 by a plurality of TMs generated and transmitted as described above will be described with reference to FIGS. Hereinafter, the case where the receiving PLC modem 100B receives the communication frame 800 will be described.

  As described above, pilot symbols 814, 824, and 834 are inserted into the communication frame 800 of a plurality of TMs at the timing of switching TMs. Also, the timing for switching TM is the timing for switching the phase region. The number of symbols of pilot symbols 814, 824, and 834, which are known signals, is fixed, and the number of symbols of payload 813 to which TM2 is assigned and the number of symbols of payload 823 to which TM3 is assigned are necessarily the same number of symbols. Become. In other words, the number of symbols of payload lengths 813 and 823 is fixed, that is, the number of symbols is known. Thus, the number (length) of symbols obtained by adding pilot symbols 814 and payload 813 is the same as that in phase region B.

  Therefore, the payload at the middle stage (payload 813 when replaced with FIG. 10) other than the head and tail payload (payloads 803 and 833 when replaced with FIG. 10) to which the head and tail TM (TM1 and TM4 when replaced with FIG. 10) are assigned. And 823) have the same number of symbols. This is not limited to the number of TMs used in the communication frame. Needless to say, the number of symbols in the payloads 803 and 833 may be the same as the number of symbols in the payloads 813 and 823.

  The receiving PLC modem 100B calculates the number of symbols in the payload 833 from the information stored in the frame control 802. That is, the preamble 801, the frame control 802, the payloads 803, 813, and 823, and the pilot symbols 814, 824, and 834 can have a known number of symbols. Subtracting the number of symbols of 801 and frame control 802), the number of symbols of payload 833 can be calculated.

  When the transmitting PLC modem 100A transmits the communication frame 800 to the receiving PLC modem 100B, the frame control 802, as described above, determines the number of symbols of the entire communication frame 800 (excluding the preamble 801 and the frame control 802), and TM1. Information on the number of symbols of the used payload 803 and the beginning TM number is included. Further, the number of symbols of the preamble 801, the number of symbols of the frame control 802, and the number of pilot symbols, which are known signals, are known to the receiving PLC modem 100B.

  Therefore, by storing this information in the frame control 802, the receiving-side PLC modem 100B can receive only by matching the timing with the preamble 801. The reason will be described below.

  When the receiving PLC modem 100B receives the communication frame 800, the multiple TM parameter extracting unit 37 of the receiving PLC modem 100B first extracts information of the frame control 802. The multiple TM parameter extraction unit 37 notifies the AC timing control unit 38 of the number of symbols of the payload 803 and the entire communication frame 800 (excluding the number of symbols of the preamble 801 and the frame control 802), and the demodulated TM control unit 39 Notify

  The demodulation TM control unit 39 reads TM1 stored in the main IC or the memory 240 from the first TM number, and notifies the data determination unit 35 and the decoding unit 36 of information related to this TM1, whereby the data determination unit 35 and the decoding unit 36 are decoded. The converting unit 36 demodulates the payload 803.

  On the other hand, the AC timing control unit 38 starts counting from the time when the frame control 802 is received, counts the number of symbols of the payload 803, and controls the time when the payload 803 is received. Further, the AC timing control unit 38 notifies the demodulation TM control unit 39 and the pilot symbol control unit 40 of the end of the payload 803. At this time, the demodulation TM control unit 39 stops its operation. The pilot symbol control unit 40 notifies the data extraction unit 32 of the end of the payload 803, and the data extraction unit 32 stops its operation.

  At this time, the pilot symbol 814 is signal-processed by the wavelet transform unit 31. Therefore, the AC timing control unit 38 notifies the demodulation TM control unit 39 and the pilot symbol control unit 40 of the beginning of the payload 813 (in other words, the end of the pilot symbol 814), and the pilot symbol control unit 40 further extracts this information as data. Notify unit 32. As a result, the data extraction unit 32 starts extracting the payload 813. On the other hand, the demodulation TM control unit 39 reads TM2 and notifies the data determination unit 35 and the decoding unit 36 of information related to TM2. Thereby, the data determination unit 35 and the decoding unit 36 demodulate the payload 813.

  As described above, by repeating this procedure, the receiving side PLC modem 100B can receive the communication frame 800. Note that one TM code (here, a number) is assigned to one phase region. In addition, when the phase region is shifted by one, the TM number is similarly shifted by one. Therefore, by extracting the first TM number, the next TM number can be automatically grasped. In the present embodiment, TM numbers are assigned consecutively, but the order of TM numbers may be determined in advance between the sending PLC modem 100A and the receiving PLC modem 100B. Therefore, the TM number may be assigned like a gray code.

  From the above, the receiving-side PLC modem 100B can grasp the TM switching timing in the communication frame 800 without confirming the phase region of the AC waveform that is the transmission path. Thereby, the receiving side PLC modem 100B can receive the communication frame 800. In addition, the AC zero cross detector 25 is not necessary in the functional block diagram of FIG. 6, and the receiving-side PLC modem 100B can receive the communication frame 800 without confirming the phase region in which the communication frame 800 is transmitted.

(Embodiment 2)
The second embodiment will be described below with reference to the drawings. FIG. 13 is a flowchart illustrating an example of a communication parameter and frame format determination method according to the second embodiment. Here, members and steps having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, different examples of the communication parameter and frame format determination method described in Embodiment 1 will be described. The difference between the present embodiment and the first embodiment is that transmission path estimation is performed by recognizing the phase area a plurality of times after the frame format becomes pilot (ON), and a new TM specific to the plurality of phase areas is obtained. It is a point to do. The plurality of new TMs are phase region specific TMs without training. Hereinafter, this different point will be described in detail. As in the first embodiment, the side that transmits data is the transmitting PLC modem 100A, and the side that receives the data is the receiving PLC modem 100B.

  In step S119, the communication parameter setting unit 11 of the transmitting PLC modem 100A determines the frame format to be a plurality of TMs (ON) and pilots (ON). Unlike the first embodiment, when the current TM pilot (ON) or the new TM pilot (ON) is the winner of training, the communication parameter setting unit 11 sets the frame format to a plurality of TM (ON).

  In step S120, as described above, the transmission-side PLC modem 100A performs transmission path estimation that recognizes the phase region a plurality of times in succession, and acquires a plurality of new TMs. It is desirable that the specific TMs in the phase regions A to P are aligned by performing transmission path estimation multiple times here. If they can be arranged, it is not necessary to use the base TM0 when actually transmitting data, and it is possible to perform communication by always using a TM suitable for the phase region in which data is transmitted.

  As described above, in the present embodiment, when the frame format becomes a plurality of TM (ON), a plurality of TMs peculiar to the phase region are obtained continuously, so immediately after the frame format becomes a plurality of TM (ON). Communication can be performed using a plurality of suitable TMs. Since the specific TMs are easily arranged in the phase areas A to P before repeating the training many times, the transmission rate is improved.

(Embodiment 3)
Hereinafter, Embodiment 3 will be described with reference to the drawings. FIG. 14 is a functional block diagram of the PLC modem according to the third embodiment, and FIG. 15 is a flowchart showing an example of a communication parameter and frame format determination method according to the third embodiment. Here, members and steps having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, different examples of the communication parameter and frame control determination method described in the first and second embodiments will be described. As a difference from Embodiments 1 and 2, in this embodiment, it is determined whether or not to insert a pilot symbol in a communication frame based on the determination of the presence or absence of transmission path fluctuation. Hereinafter, this different point will be described in detail.

  FIG. 14 is obtained by adding a fluctuation detector 15 to the configuration of FIG. The fluctuation detection unit 15 is a block that accumulates the packet retransmission rate in the period of the AC waveform and detects the presence or absence of transmission line fluctuation from the error rate.

  Hereinafter, the communication parameter and frame control determination method of the present embodiment will be described with reference to the flowchart of FIG. As in the first and second embodiments, the side that transmits data is the transmitting PLC modem 100A, and the side that receives the data is the receiving PLC modem 100B.

  In step S121, the transmitting-side PLC modem 100A performs transmission path fluctuation detection. The communication unit 14 performs actual communication using the current TM, and the communication performance acquisition unit 12 acquires an error rate and a retransmission rate in this communication. Based on this error rate or retransmission rate, the fluctuation detector 15 detects the presence or absence of transmission path fluctuations in the transmission path.

  Similarly, in step S122, the transmitting-side PLC modem 100A performs transmission path fluctuation detection. Communication is actually performed using the new TM, and the communication performance acquisition unit 12 acquires an error rate and a retransmission rate in this communication. Based on this error rate or retransmission rate, the fluctuation detector 15 detects the presence or absence of transmission path fluctuations in the transmission path.

  In step S123, the route is changed according to the presence or absence of transmission path fluctuations. Therefore, when the transmission path fluctuation is not detected by the training in step 121 or step S122, the process proceeds to step S112, and when the transmission path fluctuation is detected, the process proceeds to step S111.

  Further, in this embodiment, in order to detect transmission path fluctuation, communication is actually performed in steps S121 and 122. However, transmission path fluctuation detection may be performed during the training in step S104.

  Further, the fluctuation detecting unit 15 has a function of detecting a sudden change in the transmission path environment. The fluctuation detection unit 15 always detects the fluctuation of the transmission path from the error rate acquired by the communication performance acquisition unit 12. For example, when communication is performed using a communication frame based on a single TM, but the error rate suddenly increases, it is estimated that the transmission path environment has changed. Therefore, the fluctuation detection unit 15 issues a command for resetting the current communication parameter and frame format to the communication parameter setting unit 11. As a result, the current communication parameter and frame format are reset, and the transmitting-side PLC modem 100A performs the communication parameter and frame format determination flow again from step S101. Thereby, it is possible to switch from a single TM to a plurality of TMs. The cause of the change in the transmission path environment is that a charger or the like sharing the power line with the PLC modem 100 is disconnected from the connection with the power line.

  Similarly, for example, when communication is performed using a plurality of TMs, when the error rate rapidly decreases, it is presumed that the state of the transmission path has suddenly improved. Therefore, the fluctuation detection unit 15 detects a sudden change in the transmission path, and issues a command to the communication parameter setting unit 11 to reset the current communication parameter and frame format. As a result, the current communication parameter and frame format are reset, and the transmitting PLC modem 100A determines the communication parameter and frame format again from step 101, so that switching from a plurality of TMs to a single TM is possible.

  Note that, regardless of the plurality of frame formats TM (ON / OFF), the fluctuation detection unit 15 may reset the communication parameters and the frame format when detecting a sudden change in the transmission path.

  As described above, also in this embodiment, it is possible to set communication parameters according to the state of the transmission path. Furthermore, if transmission path fluctuations are not detected, it is not necessary to insert unnecessary pilot symbols into a communication frame and transmit, so that more effective data can be transmitted in one communication frame. In addition, since a communication frame is composed of a plurality of TMs even when a change in the transmission path is detected, a TM corresponding to the state of the transmission path in each of the phase regions A to P divided as in the first embodiment should be used. In addition, ACK can be reduced and overhead can be reduced.

  The transmission path of the PLC modem 100 is a power line, and the transmission line environment is likely to change because the power line is shared with other electronic devices. Even after the communication parameter is determined, the fluctuation detection unit 15 constantly monitors the change in the transmission path environment, so that the current communication parameter can be reset once in response to the change in the transmission path environment. Therefore, PLC modem 100 in the present embodiment can cope with a change in the transmission path environment by determining communication parameters again.

  In the first to third embodiments, one period of the AC waveform is divided into 16, but the number need not be limited to 16. If the number of divisions is increased, a TM that is more suitable for the state of the transmission path can be used. However, the amount of TM to be stored increases and more pilot symbols are inserted.

(Embodiment 4)
The fourth embodiment will be described below with reference to FIGS. 19 (a) and 19 (b). 19 (a) and 19 (b) are diagrams showing various configurations of communication frames in the fourth embodiment. Here, members and steps having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, different examples of communication frames using a plurality of TMs described in the first embodiment will be described.

  First, the communication frame shown in FIG. FIG. 19A shows an example of a communication frame in which the pilot symbol insertion position is manipulated according to the acquired TM. The transmitting-side PLC modem 100A selects a TM to which a large number of information bits can be allocated (a large amount of data can be transmitted) from the acquired TM1 to TM4, and manipulates the pilot symbol insertion position. , Make effective use of this TM. FIG. 19A is an example when TM3 is a TM to which the most information bits can be allocated.

  A pilot symbol for notifying the receiving side PLC modem 100B of the switching between TM2 and TM3 is inserted at the tail of the phase region B. A pilot symbol for notifying the receiving side PLC modem 100B of the switching between TM3 and TM4 is inserted at the head of the phase region D. By manipulating the position of the pilot symbol as described above, the payload to which TM3 is assigned is generated with a length corresponding to the phase region C. Thereby, the length of the payload to which TM3 is assigned can be maximized. That is, it is possible to transmit this communication frame by using TM3, which can allocate the most information bits among TM1 to TM4, among the communication frames. As described above, the transmission rate can be improved by effectively using TM3 capable of transmitting a large amount of data.

  Next, the communication frame shown in FIG. 19B will be described. FIG. 19B shows an example of a communication frame in which a payload is generated with a length straddling the phase region. FIG. 19B is an example when TM2 and TM3 are similar TMs.

  Since TM2 and TM3 are similar TMs, in other words, since the state of the transmission path in phase regions B and C is the same, the effect of switching TMs in phase regions B and C is small. For this reason, no pilot symbol is inserted at the boundary between the phase regions B and C (time t2). As a result, the proportion of valid data in the communication frame increases, so that transmission efficiency can be improved. In FIG. 19B, TM3 is assigned to the payload transmitted across the phase regions B and C, but TM2 may be assigned.

  In the communication frames shown in FIGS. 19A and 19B, since the pilot symbol insertion positions are not regular, it is necessary to store information on the lengths of the payloads to which TM1 to TM4 are assigned in the frame control. There is. Alternatively, it is necessary to store information on the length of the entire communication frame and the length of each payload to which TM1 to TM3 are assigned. Furthermore, in the communication frame shown in FIG. 19B, since the TM numbers are not continuous, it is necessary to notify the receiving side PLC modem 100B of the TM number to be used in advance. The transmitting-side PLC modem 100A may notify the receiving-side PLC modem 100B of this TM number alone, or may store it in the frame control and notify it. Similarly, the transmitting PLC modem 100A does not store the leading TM number, the number of symbols in the leading payload, and the number of symbols in the entire communication frame in the frame control before transmitting the leading payload to the receiving PLC modem 100B. You may notify alone.

  Embodiments 1 to 4 can be combined as appropriate.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2010-171630 filed on July 30, 2010, the contents of which are incorporated herein by reference.

  The above-described embodiments are useful as a communication method, a communication device, and a communication frame generation method for performing communication using a plurality of TMs.

DESCRIPTION OF SYMBOLS 11 Communication parameter setting part 12 Communication performance acquisition part 13 Comparison part 14 Communication part 15 Fluctuation detection part 21 Encoding part 22 Primary modulation part 23 Frame generation part 24 Inverse wavelet transformation part 25 AC zero cross detection part 26 Phase area control part 27 Pilot symbol Insertion control unit 28 Modulation TM control unit 29 FC generation unit 31 Wavelet conversion unit 32 Data extraction unit 33 Transmission path estimation unit 34 TM determination unit 35 Data determination unit 36 Decoding unit 37 Multiple TM parameter extraction unit 38 AC timing control unit 39 Demodulation TM control unit 40 Pilot symbol control unit 100 PLC modem 210 Main IC
211 CPU
212 PLC / MAC block 213 PLC / PHY block 220 Analog part (AFE / IC)
240 Memory 800, 840, 850 Communication frame 801, 841, 851 Preamble 802, 842, 852 Frame control 803, 813, 823, 833, 843, 853 Payload 814, 824, 834, 854 Pilot symbol

Claims (17)

A communication method for transmitting a communication frame using a first communication parameter according to a state of a transmission path in a first section and a second communication parameter according to a state of a transmission path in a second section,
Transmitting the first data assigned the first communication parameter in the first section;
Transmitting a pilot symbol at a boundary between the first interval and the second interval;
Transmitting the second data assigned the second communication parameter in the second interval;
A communication method characterized by the above. The communication method according to claim 1,
Before transmitting the first data in the first interval,
Transmitting frame control including pilot symbol information and communication parameter information;
A communication method characterized by the above. The communication method according to claim 2,
Before sending the frame control,
Determining a configuration of the communication frame to be transmitted including the frame control, pilot symbols, first data, and second data;
The communication frame is transmitted based on a configuration of the communication frame;
A communication method characterized by the above. The communication method according to claim 3, wherein
Determining the configuration of the communication frame such that the sum of the length of the second data and the length of the pilot symbol is equal to the length of the second interval;
A communication method characterized by the above. The communication method according to claim 4,
The frame control stores information on the length of the communication frame and information on the length of the first data.
A communication method characterized by the above. The communication method according to any one of claims 1 to 5,
After obtaining at least one communication parameter at a first time,
Obtaining communication parameters in a second time shorter than the first time;
A communication method characterized by the above. The communication method according to any one of claims 1 to 6,
The transmission line is a power line;
The first section and the second section are specific phase regions of an AC waveform on the power line.
A communication method characterized by the above. A communication device that performs communication using a communication frame across a plurality of sections using communication parameters according to the state of the transmission path,
A section control unit for identifying the transmission path into at least a first section and a second section;
A communication parameter acquisition unit that acquires a first communication parameter according to a state of a transmission path in the first section and a second communication parameter according to a state of the transmission path in the second section;
A communication parameter holding unit for storing the first communication parameter and the second communication parameter acquired by the communication parameter acquisition unit;
A configuration determining unit that determines a configuration of a communication frame scheduled to be transmitted using the first communication parameter and the second communication parameter;
A communication parameter control unit that reads out the first communication parameter and the second communication parameter from the communication parameter holding unit;
Based on the configuration of the communication frame, the first communication parameter read by the communication parameter control unit is assigned, the first data to be transmitted to the first section is generated, and the second communication parameter is assigned. A communication frame generation unit that generates second data to be transmitted in a second period and inserts a pilot symbol between the first data and the second data;
And a transmission unit that transmits the first data, the pilot symbol, and the second data. The communication device according to claim 8,
A frame control generator for storing pilot symbol information and communication parameter information in the frame control;
A communication device comprising: The communication device according to claim 9,
The configuration determining unit
Determining the configuration of the communication frame such that the sum of the length of the second data and the length of the pilot symbol is equal to the length of the second interval;
A communication device. The communication device according to claim 10,
The frame control generation unit
Storing the communication frame length information and the first data length information in the frame control;
A communication device. The communication device according to any one of claims 8 to 11,
The communication parameter acquisition unit
After obtaining at least one communication parameter at a first time,
Obtaining communication parameters in a second time shorter than the first time;
A communication device. The communication device according to any one of claims 8 to 12,
The transmission line is a power line;
The first section and the second section are specific phase regions of an AC waveform on the power line.
A communication device. Transmitting the first data assigned the first communication parameter according to the state of the transmission path in the first section in the first section;
Transmitting a pilot symbol at a boundary between the first interval and a second interval adjacent to the first interval;
Transmitting the second data assigned with the second communication parameter according to the state of the transmission path in the second section in the second section;
A communication frame generation method for generating a communication frame by transmitting at least the first data, the pilot symbol, and the second data. The communication frame generation method according to claim 14,
Before sending the first data,
Transmitting frame control including pilot symbol information and communication parameter information;
A communication frame generation method characterized by the above. The communication frame generation method according to claim 15,
The frame control is
Including information on the length of the first data and information on the length of the communication frame,
A communication frame generation method characterized by the above. The communication frame generation method according to any one of claims 14 to 16, comprising:
The second data is:
Generated to be equal to the difference between the length of the second interval and the length of the pilot symbol;
A communication frame generation method characterized by the above.

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