JP4009983B2 - Power line carrier communication equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power line carrier communication device that superimposes a plurality of communication carriers on a power line, and an algorithm for selecting an optimal communication method in accordance with the noise environment and attenuation environment of the power line, and selecting the optimal communication method The present invention relates to a method for realizing stable communication later.
[0002]
[Prior art]
Noise environment and attenuation of power lines such as in buildings, homes, distribution lines, and transmission lines vary depending on devices connected to the power lines. Especially in buildings and homes, the power supply of devices is frequently turned on and off, and the noise and attenuation caused by this are changed from moment to moment.
[0003]
In recent years, household appliances such as fluorescent lamps are often inverter-controlled, and noise generated by the inverter control may be higher than the level of communication signals used for power line conveyance. The communication used requires a communication system that is resistant to noise and attenuation.
[0004]
Therefore, as means for solving this, when a plurality of narrowband modulated signals for power line carrier are generated and transmitted as shown in Japanese Patent Laid-Open No. 11-136203, a plurality of carriers are always output, and the most out of them is output. By selecting and receiving a modulated signal that increases the received signal, it is made stronger against attenuation and noise, but even if multiple carriers are output, if all carriers are buried in noise, It becomes impossible to receive.
[0005]
Further, as means for solving the problem of the above-mentioned Japanese Patent Application Laid-Open No. 11-136203, there is a low-speed frequency hopping method used in a wireless communication system as shown in Japanese Patent Application Laid-Open No. 11-191747. FIG. 19 is a flowchart of the frequency changing process of the conventional low-speed frequency hopping spread spectrum communication system disclosed in Japanese Patent Laid-Open No. 11-191747.
[0006]
As for the operation, as shown in FIG. 19, the number of retries is counted for each frequency constituting the hopping pattern, and the frequency with bad communication state is changed to the spare frequency all at once. When used in a power line carrier communication apparatus, communication can be performed by changing only the carrier to a spare carrier when the communication performance of any of the simultaneously output carriers deteriorates.
[0007]
[Problems to be solved by the invention]
In the conventional power line carrier communication apparatus as described above, as shown in Japanese Patent Application Laid-Open No. 11-191747, even if a carrier whose communication performance is deteriorated is changed to a spare carrier, the same level of noise in the spare carrier frequency band. If there is a large amount of noise or if there is a large amount of noise, the communication quality cannot be improved, and if the noise is large in all frequency bands used for communication or if the attenuation is large, all carriers Since the S / N ratio deteriorates, the communication method has a problem that it is difficult to improve communication quality.
[0008]
The present invention has been made to solve the above-described problems, and can communicate at a transmission rate having an optimum S / N ratio margin adapted to the transmission quality of the power line such as power line noise and signal attenuation. Thus, a power line carrier communication apparatus having a transmission speed changing algorithm capable of quickly improving the communication state regardless of the state of transmission quality of the power line is obtained.
[0009]
[Means for Solving the Problems]
  In the power line carrier communication apparatus according to the present invention, the S / N ratio measuring means for measuring the S / N ratio of the received carrier, and the frame structure of the carrier, the portion indicating the demodulation method of the data part is a fixed modulation method. Modulation / demodulation method changing means for changing the data portion to a variable modulation method, and demodulating the data portion based on a portion indicating the demodulation method of the data portion in the frame at the time of carrier reception, and by the S / N ratio measuring meansAverage the S / N ratio of the received carrier for n times.Based on the S / N ratio, the modulation / demodulation method of the data part can be changed or maintained by the modulation / demodulation method changing means.However, when shifting to a modulation / demodulation method with a low transmission rate, the shift of the modulation / demodulation method is determined with a smaller number of times of averaging than when shifting to a modulation / demodulation method with a high transmission rate.Is.
[0010]
Further, when the carrier portion receives the data portion based on the portion indicating the demodulation method of the data portion and the S / N ratio of the carrier received by the S / N ratio measuring means deteriorates, the modulation / demodulation method changing means The data portion is sequentially shifted to a modulation / demodulation method having a low transmission rate, and when the S / N ratio is improved, the data portion is sequentially shifted to a modulation / demodulation method having a high transmission rate.
[0011]
Further, the data portion is demodulated based on the portion indicating the demodulation method of the data portion in the frame at the time of receiving the carrier, and the data portion is changed by the modulation / demodulation method changing means based on the S / N ratio of the received carrier by the S / N ratio measuring means. This modulation / demodulation method directly shifts to a modulation / demodulation method with the fastest transmission rate that can be communicated.
[0012]
The modulation / demodulation method changing means includes carrier frequency storage means for storing the carrier frequency and carrier frequency changing means for changing the carrier frequency, based on the S / N ratio of the received carrier by the S / N ratio measuring means. Therefore, when shifting the modulation / demodulation method of the data portion, the carrier frequency is changed by the carrier frequency changing means, starting from the carrier frequency before the transfer stored by the carrier frequency storage means.
[0014]
Further, there is provided means for setting an initial modulation / demodulation method used at power-on or reset.
[0015]
In addition, when shifting to a modulation / demodulation method with a low transmission rate, the modulation / demodulation method is directly shifted to a modulation / demodulation method with the fastest transmission rate that can be communicated. It is to be migrated.
[0016]
Further, when the frame configuration is a variable modulation method and the modulation / demodulation method is changed, the modulation / demodulation method to be switched based on the S / N ratio of the carrier received before that is shown in the frame, and all the power lines connected to the power line The power line carrier communication apparatus receives the frame and transmits / receives the next frame by the modulation / demodulation method indicated in the frame.
[0018]
In addition, the frame length is indicated in the portion indicating the demodulation method of the data portion, the end of the frame is detected from the frame length at the time of carrier reception, and the next frame is transmitted / received after a predetermined frame interval from the end of the frame It is.
[0019]
When a default frame is received at the time of carrier reception, a default frame indicating a modulation / demodulation method currently transmitted / received between the communication apparatuses is transmitted to the power line carrier communication apparatus that transmitted the frame.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 is an overall configuration diagram of a power line carrier communication device according to Embodiment 1 of the present invention, FIG. 2 is a diagram showing state transitions when the modulation / demodulation method of the power line carrier communication device is sequentially changed, and FIG. 3 is this power line FIG. 4 is a diagram showing a modulation / demodulation method of the power line carrier communication device, FIG. 5 is a diagram showing a communication method of the power line carrier communication device, and FIG. 6 is a modulation / demodulation of the power line carrier communication device. It is a related figure of a system and transmission rate.
[0021]
In FIG. 1, reference numeral 1 denotes a power line carrier communication apparatus, which includes a coupling circuit 2 with a power line 8, an A / D (analog / digital) converter 3, a D / A (digital / analog) converter 4, and a digital signal processor 5. Yes. The digital signal processor 5 performs modulation / demodulation signal processing and communication control, and includes an S / N ratio measuring means 6 for measuring the S / N ratio of the carrier, and measuring the S / N ratio by the S / N ratio measuring means 6. Modulation / demodulation method changing means 7 for changing the modulation / demodulation method of the power line carrier signal according to the result is provided.
Note that a plurality of terminals having the power line carrier communication apparatus 1 are connected to the power line 8, and FIG. 1 shows one power line carrier communication apparatus among these terminals.
[0022]
Next, the operation will be described.
First, preconditions and the like for implementing this algorithm of the power line carrier communication apparatus will be described with reference to FIGS. 3, 4, and 5.
In the communication frame of FIG. 3, the shaded portion is called a header portion, and the non-shaded portion is called a payload portion. The header modulation method is a fixed modulation method, and is always the same even if the payload modulation method is changed. For example, it is fixed by DBPSK (Differential binary phase shift keying).
[0023]
Therefore, all terminals on the power line 8 can receive and decode the header part of this DBPSK. Further, since the header portion describes in what modulation method the data in the payload portion is modulated, all terminals can determine the demodulation portion of the payload portion in accordance with the instruction of the header portion. .
[0024]
Next, in the modulation scheme shown in FIG. 4, (a) DBPSK can transmit either “0” or “1” in binary code in one unit time.
In addition, (b) DQPSK (Differential Quarant Phase Shift Keying) is a binary code in which two bits of “00”, “01”, “10”, and “11” are converted into one unit time. It can be sent. Therefore, it is possible to realize a speed twice as high as the transmission speed of DBPSK.
[0025]
Furthermore, D8PSK (Differential 8 Phase Shift Keying) of (c) is “000”, “001”, “010”, “011”, “100”, “101” in binary code. , “110” and “111” can be transmitted in one unit time. Therefore, it is possible to realize a speed three times the transmission speed of DBPSK.
[0026]
Next, FIG. 5 shows how the data of FIG. 4 is distributed to the carriers on the frequency axis. There are three carriers on the frequency axis, but all three are as shown in (a). The amount of data that can be transmitted in one unit time differs between the case of superimposing the same data on and the case of superimposing different data in turn on each of the three as shown in (b). For example, as shown in (b), if different data are put on three carriers, a transmission speed of three times can be realized. Accordingly, FIG. 6 summarizes the difference in transmission speed due to the difference in the modulation schemes of DBPSK, DQPSK, and D8PSK, and the difference of the data superposition schemes for the three carriers.
[0027]
Next, the algorithm of the power line carrier communication apparatus will be described with reference to FIG.
First, the modulation / demodulation method is started by the modulation / demodulation method change means 7 in the D8PSK × 3 communication mode (D8PSK change method with different data superimposed on three carriers). In this state, when a frame on the power line 8 which is a transmission path is received (including reception of frames other than the one addressed to itself), the S / N ratio measuring means 6 determines the S / N ratio of each of the three carriers. The signal point is calculated from the deviation value, and the result is stored in a memory (not shown) in the digital signal processor 5. Then, n S / N ratio results are stored and averaged.
[0028]
Looking at this averaged value, all three carriers have a constant bit error rate (for example, 10) in this communication mode.^-FiveIf the S / N ratio satisfies the (bit error rate), the state remains (maintains). However, if even one of the three carriers is less than this, the modulation / demodulation method changing means 7 moves the modulation / demodulation method to the next state, and DQPSK × 3 (DQPSK changing method is different for three carriers). The communication mode of superimposing data is tried ((1) in FIG. 2).
[0029]
Next, in the communication mode of DQPSK × 3, as described above, the average value of the S / N ratio is seen, and a constant bit error rate (for example, 10^-FiveIf the S / N ratio satisfies the (bit error rate), the state remains in this state. However, if even one of the three carriers is less than this, the modulation / demodulation method is moved to the next state, and DBPSK × 3 communication (different data is superimposed on three carriers by the DBPSK changing method) The mode is tried ((2) in FIG. 2).
[0030]
Next, in the DBPSK × 3 communication mode, as described above, the average value of the S / N ratio is seen, and a constant bit error rate (for example, 10) is set for all three carriers.^-FiveIf the S / N ratio satisfies the (bit error rate), the state remains in this state. However, if even one of the three carriers is less than this, the modulation / demodulation method is moved to the next state and D8PSK × 1 (the same data is superimposed on all three carriers by the D8PSK change method). ((3) in FIG. 2).
[0031]
Next, in the D8PSK × 1 communication mode, the received S / N ratio of the three carriers is stored in the memory in the digital signal processor 5 in the same manner as described above. Then, n S / N ratio results are stored and averaged. From this averaged value, among the three carriers, the carrier having the maximum S / N ratio has a constant bit error rate (for example, 10^-FiveIf the S / N ratio satisfies the (bit error rate), the state remains in this state. However, if this is not satisfied, the modulation / demodulation method is moved to the next state, and a DQPSK × 1 communication mode is attempted ((4) in FIG. 2).
[0032]
Next, in the DQPSK × 1 communication mode, the received S / N ratio of the three carriers is stored in the memory in the same manner as described above. Then, n S / N ratio results are stored and averaged. From this averaged value, among the three carriers, the carrier having the maximum S / N ratio has a constant bit error rate (for example, 10^-FiveIf the S / N ratio satisfies the (bit error rate), the state remains in this state. However, if this is not satisfied, the modulation / demodulation method is moved to the next state and moved to the DBPSK × 1 communication mode ((5) in FIG. 2).
The above description is a sequence for lowering the transmission rate when the communication quality of the power line 8 is poor such as large attenuation or large noise.
[0033]
Next, a sequence for increasing the transmission rate when the communication quality of the power line 8 is good, such as low attenuation and low noise, is shown. The sequence for increasing the transmission rate is the reverse of the sequence for decreasing the transmission rate.
For example, in the DQPSK × 1 communication mode, the received S / N ratio of the three carriers is stored in the memory in the same manner as described above. Then, n S / N ratio results are stored and averaged. From this averaged value, among the three carriers, the carrier with the maximum S / N ratio is a constant bit error rate (for example, 10) in D8PSK, which is one higher than DQPSK.^-FiveIf the S / N ratio is equal to or higher than mdB (for example, 3 db) from the lower limit of the S / N ratio that satisfies (the bit error rate), the modulation / demodulation method changing unit 7 sets D8PSK × 1 that is one higher level state. (6 in FIG. 2).
[0034]
Further, for example, in the DQPSK × 3 communication mode, as described above, the S / N ratio results of each of the three received carriers are stored and averaged. By looking at this averaged value, the bit error rate (for example, 10 carriers) for all three carriers to remain in the upper state in this communication mode.^-FiveIf the S / N ratio is greater than or equal to the bit error rate, the modulation / demodulation method changing means 7 moves to the D8PSK × 3 communication mode, which is the next higher state ((7) in FIG. 2). .
[0035]
In the sequence for increasing the transmission speed described above, the case where the communication mode is DQPSK × 1 and DQPSK × 3 has been described. However, in other communication modes, it is determined whether or not movement to the next higher state is possible as described above. If it is possible to move, it moves to a higher state (communication mode).
As described above, in the present embodiment, according to the deterioration of the S / N ratio, the modulation / demodulation method is shifted one by one in the order of the higher transmission speed, so that even when the accuracy of the calculation result of the S / N ratio is low, it is stable. It is possible to provide a transmission rate (modulation / demodulation method) that can be communicated to the network.
Moreover, since D8PSK × 1 and DBPSK × 3 have the same transmission rate, either one of the communication modes may be deleted.
[0036]
Embodiment 2. FIG.
In the first embodiment, the modulation / demodulation method is shifted one by one in descending order of the transmission speed in accordance with the deterioration of the S / N ratio. Therefore, from the initial setting of the power line carrier communication apparatus to the stable modulation / demodulation method. It may take time.
In the second embodiment, the calculation result of the S / N ratio is high in accuracy, and it is possible to immediately shift to a transmission method (modulation / demodulation method) capable of stable communication.
[0037]
FIG. 7 is a diagram showing state transitions when the modulation / demodulation method of the power line carrier communication apparatus according to Embodiment 2 of the present invention is changed directly. The overall configuration diagram of the power line carrier communication device, the configuration diagram of the communication frame, the diagram showing the modulation / demodulation method, the diagram showing the communication method, and the relationship diagram between the modulation / demodulation method and the transmission rate are shown in FIGS. Is used.
[0038]
First, the communication mode starts from D8PSK × 3. In this state, when a frame on the power line 8 as a transmission path is received (including reception of frames other than the one addressed to itself), the S / N ratio measuring means 6 determines the S / N ratio of each of the three carriers. Calculate from the deviation value of the signal point and store the result in the memory. Then, n S / N ratio results are stored and averaged.
[0039]
Looking at this averaged value, all three carriers have a constant bit error rate (for example, 10) in this communication mode.^-FiveIf the S / N ratio satisfies the (bit error rate), the state remains in this state. However, if even one of the three carriers is less than this, the S / N ratio (10^-FiveThe modulation / demodulation method changing means 7 directly shifts to a state that is equal to or higher than the lower limit of the S / N ratio that satisfies the bit error rate of (1) and closest to the lower limit.
[0040]
However, when the state is x3 (with different data superimposed on three carriers), all three carriers need to have a certain S / N ratio or more, and the state is x1 (all three In the case of superimposing the same data on one carrier), an S / N ratio of a certain value or more is sufficient for only one carrier.
When attention is paid to one carrier, the value of the S / N ratio above a certain value for both carriers is, for example, DBPSK × 3 (12.9 Kbps) and D8PSK × 1 (12.9 Kbps) at the same transmission rate. In this case, D8PSK × 1 is larger than DBPSK × 3. It should be noted that the selection criteria are different for each state.
[0041]
Therefore, the S / N ratio of each of the three carriers is stored, and based on the S / N ratios of the carriers necessary for staying in each state (two of the three are above a certain level, or only one is above a certain level). Check in order from the state of the higher transmission rate, and move directly to that state.
[0042]
Also, the value of the S / N ratio of all three carriers (value after the averaging process) or the value of the S / N ratio of one carrier is lower than the lower limit of the S / N ratio in the higher transmission rate state + mdB The S / N ratio required to stay in each state (10^-Five(S / N ratio satisfying the bit error rate) is directly shifted to a state that is larger than the lower limit and closest to the lower limit.
Here, the lower limit + mdB is set to prevent the frequent change of the current state and the upper state from occurring.
[0043]
Embodiment 3 FIG.
Next, a power line carrier communication apparatus that changes the carrier frequency used for communication according to the noise and attenuation of the power line in addition to the change of the communication mode (state) will be described.
FIG. 8 is a diagram showing the change of the modulation / demodulation method and the carrier frequency of the power line carrier communication apparatus according to Embodiment 3 of the present invention, and FIG. 9 is the change of another modulation / demodulation method of the power line carrier communication apparatus and the carrier frequency. It is the figure which showed the change.
[0044]
8 and 9, the communication modes of D8PSK × 3, DQPSK × 3, DBPSK × 3, D8PSK × 1DQPSK × 1, DBPSK × 1 are D8 × 3, DQ × 3, DB × 3, D8 × 1, DQ, respectively. Abbreviated as x1 and DBx1. The overall configuration diagram of the power line carrier communication apparatus uses FIG. 1, and the digital signal processor 5 stores and changes the carrier frequency.
[0045]
Next, the operation will be described.
When changing the carrier used for communication due to the noise of the power line 8, for example, when changing the modulation / demodulation method from the D8PSK × 3 communication mode to the DBPSK × 1 communication mode, the frequency position that has remained for a certain period of time or more To evaluate.
[0046]
That is, as shown in FIG. 8, normally, in the communication mode of D8PSK × 3, starting from a position with a high carrier frequency (hereinafter referred to as H position. For example, the frequency band is 276 Hz to 413 Hz), the power line 8 on the transmission line is used. When a frame is received (including reception of frames other than the one addressed to itself), the S / N ratio measuring means 6 calculates the S / N ratio of each of the three carriers from the deviation value of the signal point, and the result is The data is stored in the memory in the digital signal processor 5, and the results of the S / N ratio are stored for n times, averaged, and the S / N ratio is evaluated.
[0047]
Here, the S / N ratio is below a certain value (for example, 10^-FiveThe carrier frequency is changed to the center position (hereinafter referred to as M position, for example, the frequency band is 207 Hz to 345 Hz). Thereafter, the S / N ratio is evaluated in the same manner as in the H position.
Here, the S / N ratio is below a certain value (for example, 10^-FiveThe carrier frequency is changed to a low position (hereinafter referred to as L position. For example, the frequency band is 138 Hz to 276 Hz). Thereafter, the S / N ratio is evaluated in the same manner as in the H position.
[0048]
Here, the S / N ratio is below a certain value (for example, 10^-FiveBit error rate), the communication mode is changed from D8PSK × 3 to DQPSK × 3, the transmission speed is changed, the carrier frequency is set to the H position in the same manner as described above, and the S / N ratio is evaluated. The ratio is below a certain value (for example, 10^-FiveThe bit error rate), the M position and the L position are changed in this order for evaluation.
[0049]
Similarly, if the S / N ratio is below a certain level, the communication mode is sequentially shifted to DBPSK × 3, D8PSK × 1DQPSK × 1, DBPSK × 1, and the transmission rate is changed. Evaluation is performed in the order of H position, M position, and L position.
As described above, the S / N ratio is evaluated, and a modulation / demodulation method and a carrier frequency capable of communication are selected.
[0050]
In the modulation / demodulation method and the carrier frequency selection described above, for example, even if the carrier frequency was able to communicate at the M position in the previous communication mode, it is moved to the H position after changing the modulation / demodulation method regardless of the past history. Therefore, communication may not be possible due to a difference in carrier frequency.
Therefore, as shown in FIG. 9, in order to change the modulation / demodulation method when communication can be performed at the same position (for example, DBPSK × 3 L position) for a certain period or longer, the position (for example, D8PSK × 1 L) for which communication has been performed for a certain period or longer can be changed. (Position).
[0051]
In addition, when there are a plurality of positions that have been able to communicate for a certain period or longer (for example, DQPSK × 1 H position and M position), the position moves in the longest order (for example, DBPSK × 1 H position to M position) If it is the same period, it moves from the H position.
The reason why the H position is dominant is that noise in the power line 8 is frequently generated in the low frequency side due to the recent increase in inverter devices.
[0052]
Embodiment 4 FIG.
In the third embodiment, when the modulation / demodulation method and the position of the carrier frequency are moved, n frames are received, averaged, and moved based on the result. In many cases, when a system of a power line carrier communication apparatus is newly introduced, a state where communication cannot be performed for a while may be continued in order to select a modulation / demodulation method and a carrier frequency capable of communication.
[0053]
Therefore, the point for judging whether or not the condition for lowering the transmission rate by the modulation / demodulation method is set at the time of receiving the frame for n / 4 times, and the point for judging whether or not the condition for raising the modulation / demodulation method is reached is received for the frame for n times. By setting sometimes, it becomes possible to stabilize at high speed.
[0054]
For example, in a system in which the power line carrier communication device 1 of the master station and the power line carrier communication device of the slave station are one, and the master station polls the slave station every minute, when n = 12 Since the modulation / demodulation method can be changed only at 12-minute intervals, the poor communication state continues for 12 minutes, but the condition for lowering the modulation / demodulation method is n / 4 = 3 minutes. Improvement can be expected and stable at high speed.
[0055]
As described above, when changing to a modulation / demodulation method, when shifting to a modulation / demodulation method with a low transmission rate, the number of averaged data for judging the average value of the S / N ratio is set to a small value, and conversely, By setting a large number of averaged data for judging the average value of the S / N ratio when shifting to a fast modulation / demodulation method, the modulation / demodulation method is not frequently switched, and the communication quality is stabilized.
[0056]
Embodiment 5 FIG.
In the first, second, and third embodiments, when the power line carrier communication device 1 is initially installed and reset, the start point of the initial modulation / demodulation method is set to the modulation / demodulation method (D8PSK × 3) with the fastest transmission speed. However, the digital signal processor 5 has a dip switch (not shown), observes the noise and attenuation state of the power line 8 in advance, and uses the dip switch to start from an appropriate modulation / demodulation method. May be.
If the noise and attenuation amount of the power line 8 are completely unknown, the communication failure state can be more reliably avoided by setting the start point to DBPSK × 1 and increasing the transmission speed.
[0057]
Embodiment 6 FIG.
When the modulation / demodulation schemes shown in the first embodiment and the second embodiment are combined and the state shifts to a modulation / demodulation scheme with a low transmission rate, it is directly based on the averaged data as in the second embodiment. When shifting to another state and shifting to a state of a modulation / demodulation method with a high transmission rate, the average value of the S / N ratio is sequentially seen as in the first embodiment, and the modulation / demodulation rate is incremented one by one. You may move sequentially to a faster state.
[0058]
Embodiment 7 FIG.
First, communication between a plurality of power line carrier communication apparatuses in Embodiments 1 to 6 will be described. FIG. 10 is a diagram showing a communication sequence of the power line carrier communication apparatus according to the first to sixth embodiments of the present invention. 1 and 3 are used as the overall configuration diagram of the power line carrier communication device and the configuration diagram of the communication frame, respectively.
[0059]
As shown in FIG. 3, the configuration of the communication frame (transmission frame) is such that the portion indicating the modulation / demodulation method is fixed and only the data portion is changed to the optimum modulation method. In FIG. 10, the power line carrier communication apparatus A transmits a communication frame to the power line carrier communication apparatus C, the fixed part of this communication frame is modulated by DBPSK, and the demodulation method of the data part that follows thereafter is described. In this case, the data part is described in DQPSK.
[0060]
Next, the power line carrier communication apparatus C that has received the communication frame looks at the fixed part and reads the data part by switching to the modulation / demodulation method “DQPSK” for receiving the subsequent data part during frame reception. Therefore, when the power line carrier communication apparatus C switches the data portion speed to, for example, “D8PSK” based on the S / N ratio of the frame, the data portion demodulation method is described as “D8PSK” in the fixed portion of the communication frame. Then, the subsequent data portion is modulated by D8PSK and transmitted. Then, the power line carrier communication apparatus A that has received the communication frame looks at the fixed portion and reads the data portion by switching the modulation / demodulation method “D8PSK” for receiving the subsequent data portion during frame reception.
[0061]
Next, communication between a plurality of power line carrier communication devices in the seventh embodiment will be described. FIG. 11 is a configuration diagram of a communication frame of the power line carrier communication apparatus according to the seventh embodiment of the present invention, and FIG. 12 is a diagram showing a communication sequence of the power line carrier communication apparatus. Note that FIG. 1 is used as an overall configuration diagram of the power line carrier communication apparatus. In the communication frame of FIG. 11, the modulation method of the header part and the payload part can be changed.
[0062]
Next, the operation will be described.
In the seventh embodiment, one transmission frame is all modulated by the same modulation method. Therefore, first, the fact that it is desired to change the modulation method is described in a frame and transmitted. For example, in the frame transmission in FIG. 11, the modulation / demodulation method currently used for transmission / reception is D8PSK, and an instruction to switch the modulation / demodulation method from the next time to DQPSK is described in the frame.
[0063]
This change instruction is received by all the power line carrier communication apparatuses A, B, and C, and the transmission / reception modulation / demodulation method is switched immediately after reception of this frame. The power line carrier communication apparatus C changes to the DQPSK modulation / demodulation method in accordance with this change instruction, transmits the frame, and the power line carrier communication apparatus B receives the DQPSK.
As described above, communication between a plurality of power line carrier communication devices is performed, and even if the payload portion is a short frame, the modulation / demodulation scheme transmission rate and the frame transmission rate can be made to correspond to each other at 1: 1. The speed of the method can speed up the entire frame.
[0064]
Embodiment 8 FIG.
Next, a method for expressing a modulation / demodulation method using data for a predetermined time at the beginning of the frame, for example, data for two unit times, without describing in the frame that the modulation method is to be changed will be described. FIG. 13 is a diagram showing a modulation / demodulation method for a power line carrier communication apparatus according to Embodiment 8 of the present invention. The double modulation method shown in FIG. 13 is basically the same as the double modulation method shown in FIG. 4, but differs in the arrangement of coordinates shown in (a) to (c).
[0065]
As shown in FIG. 13, the binary codes DBPSK, DQPSK, and D8PSK are determined. Next, “1” is transmitted as data for one unit time at the beginning of the frame by DBPSK, and when the data is received by the DQPSK and D8PSK communication devices, they are read as “11” and “111” data, respectively. Further, when “0” is transmitted as data for one unit time at the beginning of the frame by DBPSK, the data is read as “00” and “000”, respectively.
[0066]
If the data read as “11” and “111” are interpreted as “1”, and the data read as “00” and “000” are interpreted as “0”, the top of the frame is read. Any of the DBPSK, DQPSK, and D8PSK communication devices can obtain two bits of information with two unit time data.
For example, if DBPSK is represented by 2 bits, such as “00”, DQPSK is “01”, and D8PSK is “10”, the data modulation method can be determined by referring to this.
[0067]
Embodiment 9 FIG.
Since the data transmission / reception between the communication devices described above is performed by connecting all the communication devices to the power line, when two or more communication devices transmit at the same frequency position at the same time, the receiving communication device receives the transmission contents. I can't. Therefore, it is necessary to prevent all communication devices transmitting at the same frequency position from transmitting simultaneously. For this purpose, the receiving communication device must correctly detect the end of the transmitted communication frame (transmission frame). A method for correctly detecting the end of the frame will be described below.
[0068]
When the configuration of the communication frame (transmission frame) has a portion that is a fixed modulation method as shown in FIG. 3 and only the data portion is changed to the optimum modulation method, the communication frame (transmission frame) is modulated by DBPSK of this communication frame. In the fixed portion, the double modulation scheme of the data portion following the fixed portion and the length of the data portion are described. In this case, the data part is described in DQPSK.
[0069]
FIG. 14 is a diagram showing a communication sequence of the power line carrier communication apparatus according to the ninth embodiment of the present invention, and FIG. 15 is a time transition diagram of transmission / reception between the power line carrier communication apparatuses according to the ninth embodiment of the present invention. In FIG. 15, a shaded frame indicates a received frame, and a frame not shaded indicates a transmission frame. 14 and 15, the communication devices B and C that have received the communication frame A transmitted from the communication device A switch to the modulation / demodulation method “DQPSK” that receives the subsequent data portion by looking at the fixed portion, and switch data during frame reception. The end of the frame A is accurately detected while reading the portion and looking at the length of the data portion.
[0070]
Accordingly, the communication device B that has received the communication frame A transmits the communication frame B at a certain frame interval from the end of the frame A. After that, the communication device C that has received the communication frame B accurately detects the end of the frame B by looking at the length of the data portion written in the fixed portion, and keeps a certain frame interval from the end of the frame B. The communication frame C is transmitted. Since transmission is performed based on accurate detection of the end of the frame, it is possible to prevent duplicate communication apparatuses that transmit at the same frequency position from being transmitted.
[0071]
At this time, since the communication devices B and C simultaneously detect the end of the frame A after receiving the communication frame A, the communication devices B and C may transmit at the same time. Will overlap. Accordingly, the communication device C transmits after the communication device B transmits the frame so that a difference is generated between the communication device B and the communication device C at a frame interval until the next transmission can be performed after providing a random time. To do.
[0072]
Embodiment 10 FIG.
FIG. 16 is a time transition diagram of transmission / reception between the power line carrier communication apparatuses according to the tenth embodiment of the present invention. In FIG. 16, (1) is a frame transmitted by a normal (existing) communication device, and (2) is a frame transmitted by a communication device newly connected to a power line (hereinafter referred to as “newly entered communication device”) (default). (Frame) and (3) are frames received by a normal (existing) communication device, and (4) are frames received by a newly-entered communication device. Among these, the default frame that can be received by all communication apparatuses is indicated by hatching.
[0073]
The following describes a case where a communication device is newly connected to the power line when data is transmitted / received between the power line carrier communication devices with the initial modulation / demodulation method, the modulation / demodulation method and the frequency position changed from the initial frequency position. To do.
[0074]
A frame A is transmitted from a normal (existing) communication apparatus using the current modulation / demodulation method and frequency position. However, a newly-entered communication device cannot receive the frame A because it does not know the modulation / demodulation method and frequency position that are currently transmitted / received between the communication devices and can only receive the default frame. Therefore, the end of frame A cannot be detected correctly, and frames B and C are arbitrarily transmitted as default frames.
[0075]
On the other hand, since a normal (existing) communication apparatus can receive a default frame, both frames A and B can be received. However, when frames A and B are received in duplicate, that is, from the end of frame A. If a frame B is transmitted from a newly-entered communication device before a predetermined frame interval, the frame B cannot be received because the reception permission has not been issued.
On the other hand, when a frame C is transmitted from a newly entered communication apparatus after a predetermined frame interval from the end of the frame A, the frame C can be received.
[0076]
A normal (existing) communication device receives this frame C to know the presence of a newly entered communication device. At this time, if any of the normal (existing) communication devices is set to transmit the default frame D, the newly-entered communication device can use the modulation / demodulation method currently used between the normal communication devices. And the frequency position can be grasped. After that, the newly-entered communication device can perform the communication in the modulation / demodulation method and the frequency position currently used after the frame E similarly to the normal communication device.
[0077]
In addition, even if a modulation / demodulation method / frequency position frame (frame A) and a default frame (frame B) used by a normal (existing) communication apparatus are simultaneously received, the modulation / demodulation method / frequency position frame is received. If it is set to receive (Frame A), communication can be continued without any failure.
[0078]
In the above, securing of communication means in a newly-entered communication device has been described. However, even in a normal (existing) communication device, due to the influence of noise in a wide range or by temporarily removing the connection of the communication device, etc. In some cases, the modulation / demodulation method and the frequency position used in the system may not be known. In this case, if communication is not performed even after a predetermined time has passed, if the default frame is set to be transmitted, the modulation / demodulation currently used is the same as in the case of a newly entered communication device. Can grasp the system and frequency position.
[0079]
As a specific example, FIG. 17 shows a communication apparatus configured with a relationship between a master (master station) and a slave (slave station). The master performs communication by a communication procedure (polling) for sequentially communicating with slave 1, slave 2, and slave 3. In this case, if the master (master station) does not approve the change even after waiting for a time longer than the polling cycle, the slave (slave station) recognizes that the modulation / demodulation method and frequency position currently used between the communication devices are lost. Then, a default frame is transmitted, and the currently used modulation / demodulation method and frequency position are notified.
[0080]
Embodiment 11 FIG.
Further, the communication method of the communication device may be set not only to transmit a frame only to the modulation / demodulation method and frequency position currently used between the communication devices, but also to transmit a default frame. By doing so, a newly entered communication device and a communication device whose current modulation / demodulation method and frequency position are unknown can quickly return to communication in the modulation / demodulation method and frequency position currently used between the communication devices.
[0081]
In addition, a modulation / demodulation method and a means for confirming and communicating with a modulation / demodulation method currently used between communication apparatuses will be described with reference to FIG. First, a communication apparatus (transmission side) whose modulation / demodulation method / frequency position is to be changed transmits the modulation / demodulation method / frequency position to be changed in a frame ((1) in the figure). Next, the communication device on the receiving side transmits whether the change of the modulation / demodulation method / frequency position is approved or not ((2) in the figure). Only when it is approved, the modulation / demodulation method / frequency position is changed, and transmission is performed using the desired modulation / demodulation method / frequency position ((3) in the figure). If rejected, transmission is performed without changing the modulation / demodulation method and frequency position. In this way, communication stability can be increased.
[0082]
Embodiment 12 FIG.
In the above-described embodiment, the modulation / demodulation method and the change of the frequency position are not distinguished from each other. However, when one of the change processes takes time, for example, the change of the frequency position is performed at a fixed portion of the frame. Even if it is specified, if the change process does not end before the data part is received, or if the modulation / demodulation method and frequency position change instruction are specified in the fixed part of the frame, the data amount of the fixed part will increase. It is conceivable to control both by different methods. That is, the modulation / demodulation method can be changed in the fixed part, and the frequency position can be changed in the data part. Further, it is possible to transmit extra empty data in a fixed part until the process of changing the frequency position is completed.
[0083]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
  At the time of carrier reception, the data part is demodulated based on the part indicating the demodulation method of the data part in the frame, and the S / N ratio measuring meansAverage the S / N ratio of the received carrier for n times.Based on the S / N ratio, the modulation / demodulation method of the data part can be changed or maintained by the modulation / demodulation method changing means.However, when shifting to a modulation / demodulation method with a low transmission rate, the shift of the modulation / demodulation method is determined with a smaller number of times of averaging than when shifting to a modulation / demodulation method with a high transmission rate.Therefore, it is possible to communicate by changing or maintaining the transmission rate according to the situation of the power line.
  In addition, the modulation / demodulation method is not frequently switched, and the communication quality is stabilized.
[0084]
Further, when the carrier is received, the data portion is demodulated based on the portion indicating the demodulation method of the data portion, and when the S / N ratio of the carrier received by the S / N ratio measuring means deteriorates, the modulation / demodulation method changing means changes the data portion. Is gradually shifted to a modulation / demodulation method with a low transmission rate, and when the S / N ratio is improved, a modulation / demodulation method with a high transmission rate is sequentially shifted. Therefore, the modulation / demodulation method is dynamically changed according to the noise and attenuation state of the power line. Switching can be performed sequentially, and communication can be performed at an optimal transmission rate according to the power line conditions.
[0085]
Further, the data portion is demodulated based on the portion indicating the demodulation method of the data portion in the frame at the time of receiving the carrier, and the data portion is changed by the modulation / demodulation method changing means based on the S / N ratio of the received carrier by the S / N ratio measuring means. Since the modulation / demodulation method is directly shifted to the modulation / demodulation method of the fastest transmission speed that can be communicated, when the modulation / demodulation method is switched according to the noise and attenuation state of the power line, It is possible to directly switch to the optimum modulation / demodulation method, and to shift to the optimum modulation / demodulation method at high speed.
[0086]
In addition, when the modulation / demodulation method of the data part is shifted by the modulation / demodulation method changing unit based on the S / N ratio of the received carrier by the S / N ratio measuring unit, it starts from the carrier frequency before the transition stored by the carrier frequency storage unit. Because the carrier frequency is changed by the carrier frequency changing means, when changing the modulation / demodulation method and changing the carrier frequency according to the power line noise and attenuation state, the communication is stably performed once in the modulation / demodulation method before the change. Since the S / N ratio is evaluated using the same frequency as the carrier frequency that has been made, communication can be continued stably at high speed.
[0088]
In addition, since it has means to set the modulation / demodulation method in the initial state used at power-on or reset, the initial modulation / demodulation method is automatically or manually selected at power-on or reset according to the power line noise and attenuation conditions. The modulation / demodulation method of all the power line carrier communication devices can be matched at high speed when the system is started up.
[0089]
In addition, when shifting to a modulation / demodulation method with a low transmission rate, the modulation / demodulation method is directly shifted to a modulation / demodulation method with the fastest transmission rate that can be communicated. Therefore, when shifting to a modulation / demodulation method with a low transmission rate, the state is shifted directly to a state where a S / N ratio margin can be secured, and when shifting to a modulation / demodulation method with a high transmission rate, the transmission rate is sequentially increased. Transitioning to the transmission method enables stable communication.
[0090]
Further, when the frame configuration is a variable modulation method including the header part and the modulation / demodulation method is changed, the modulation / demodulation method to be switched based on the S / N ratio of the carrier received before is shown in the frame, and the power line Since all the power line carrier communication devices connected to the receiver receive this frame and transmit / receive the next frame using the modulation / demodulation method indicated in the frame, the transmission / reception rate and frame of the modulation / demodulation method are used even if the data portion is a short frame. The transmission speed of the entire frame can be increased by increasing the modulation / demodulation method.
[0092]
In addition, since the receiving communication apparatus can correctly detect the end of the transmitted communication frame (transmission frame), communication at the same frequency position can be prevented from overlapping.
[0093]
In addition, even if the modulation / demodulation method and frequency position currently used between communication devices are not known, if the default frame is set to be transmitted, the modulation / demodulation method and frequency position currently used can be understood. Communication can be ensured.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a power line carrier communication apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a state transition diagram when changing the modulation / demodulation method of the power line carrier communication apparatus according to Embodiment 1 of the present invention;
FIG. 3 is a configuration diagram of a communication frame of the power line carrier communication apparatus according to Embodiment 1 of the present invention.
FIG. 4 is a diagram showing a modulation / demodulation method of the power line carrier communication apparatus according to Embodiment 1 of the present invention.
FIG. 5 is a diagram showing a communication method of the power line carrier communication apparatus showing Embodiment 1 of the present invention.
FIG. 6 is a relationship diagram between a modulation / demodulation method and a transmission rate of the power line carrier communication apparatus according to Embodiment 1 of the present invention.
FIG. 7 is a state transition diagram when changing the modulation / demodulation method of the power line carrier communication apparatus according to Embodiment 2 of the present invention;
FIG. 8 is a diagram showing a change in modulation / demodulation method and a change in carrier frequency of a power line carrier communication apparatus according to Embodiment 3 of the present invention.
FIG. 9 is a diagram showing another modulation / demodulation method change and carrier frequency change of the power line carrier communication apparatus according to Embodiment 3 of the present invention;
FIG. 10 is a diagram showing a communication sequence of the power line carrier communication apparatus showing the first to sixth embodiments of the present invention.
FIG. 11 is a configuration diagram of a communication frame of a power line carrier communication apparatus according to Embodiment 7 of the present invention.
FIG. 12 is a diagram showing a communication sequence of a power line carrier communication apparatus showing Embodiment 7 of the present invention.
FIG. 13 is a diagram showing a modulation / demodulation method of a power line carrier communication apparatus according to Embodiment 8 of the present invention.
FIG. 14 is a diagram showing a communication sequence of a power line carrier communication apparatus showing Embodiment 9 of the present invention.
FIG. 15 is a time transition diagram of transmission / reception of the power line carrier communication apparatus according to Embodiment 9 of the present invention.
FIG. 16 is a time transition diagram of transmission / reception of the power line carrier communication apparatus according to Embodiment 10 of the present invention.
FIG. 17 is a relationship diagram between a master and a slave of a power line carrier communication apparatus according to Embodiment 10 of the present invention.
FIG. 18 is a diagram showing a communication sequence of a power line carrier communication apparatus showing Embodiment 11 of the present invention.
FIG. 19 is a flowchart showing frequency change processing of a conventional low-speed frequency hopping spread spectrum communication system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power line carrier communication apparatus, 2 Power line coupling circuit, 5 Digital signal processor, 6 S / N ratio measurement means, 7 Modulation / demodulation system change means, 8 Power line.

Claims (9)

In the power line carrier communication device for allocating and communicating data to be superimposed on the power line to a plurality of carriers on the frequency axis,
S / N ratio measuring means for measuring the S / N ratio of the received carrier;
A modulation / demodulation method changing means for setting a frame structure of the carrier, a portion indicating a demodulation method of the data portion as a fixed modulation method, and a data portion as a variable modulation method;
With
Demodulate the data part based on the part indicating the demodulation method of the data part in the frame at the time of carrier reception,
Wherein the S / N ratio of O Ri receive carrier on the S / N ratio measuring means is n times averaged, on the basis of the S / N ratio, variable or maintaining the modulation and demodulation method of the data portion by the modulation and demodulation method change means,
A power line carrier communication apparatus characterized in that, when shifting to a modulation / demodulation method with a low transmission rate, the shift of the modulation / demodulation method is determined with a smaller number of averaging times than when shifting to a modulation / demodulation method with a high transmission rate .   The data part is demodulated based on the part indicating the demodulation method of the data part at the time of carrier reception, and when the S / N ratio of the carrier received by the S / N ratio measuring means deteriorates, the data part is 2. The power line carrier communication apparatus according to claim 1, wherein when the S / N ratio is improved, the mode is sequentially shifted to a modulation / demodulation method having a higher transmission rate.   The data portion is demodulated based on the portion indicating the demodulation method of the data portion in the frame at the time of carrier reception, and the modulation / demodulation of the data portion is performed by the modulation / demodulation method changing means based on the S / N ratio of the received carrier by the S / N ratio measuring means. 2. The power line carrier communication apparatus according to claim 1, wherein the system is directly shifted to a modulation / demodulation system with the fastest transmission rate capable of communication. Carrier frequency storage means for storing the carrier frequency;
Carrier frequency changing means for changing the carrier frequency;
With
When the modulation / demodulation method of the data part is shifted by the modulation / demodulation method changing unit based on the S / N ratio of the received carrier by the S / N ratio measuring unit, the start is made from the carrier frequency before the transition stored by the carrier frequency storage unit. 3. The power line carrier communication apparatus according to claim 1, wherein the carrier frequency is changed by the carrier frequency changing means. Power-up or power-line carrier communication apparatus according to claim 1 or 2 or 3, wherein further comprising means for setting the modulation and demodulation system in the initial state is used during reset. When shifting to a modulation / demodulation method with a low transmission rate, the modulation / demodulation method is directly shifted to a modulation / demodulation method with the fastest transmission rate that can be communicated. The power line carrier communication device according to claim 1, 2, 3, 4, or 5 . When the frame configuration is a variable modulation scheme and the modulation / demodulation scheme is changed, the modulation / demodulation scheme to be switched based on the S / N ratio of the carrier received before that is shown in the frame, and all the power lines connected to the power line carrier communication apparatus receives this frame, the power line communication apparatus according to claim 1 or 2 or 3 or 4 or 5 or 6, wherein the sending and receiving next frame demodulation scheme shown in the frame. A frame length is indicated in a portion indicating a demodulation method of the data portion, a frame end is detected from the frame length when a carrier is received, and a next frame is transmitted / received after a predetermined frame interval from the frame end. The power line carrier communication apparatus according to any one of claims 1 to 6 . When receiving a default frame at the time of carrier reception, a default frame indicating a modulation / demodulation method currently transmitted / received between communication apparatuses is transmitted to a power line carrier communication apparatus that has transmitted the frame. The power line carrier communication apparatus according to any one of 8 .

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