TW202439789A - Wired communication system for replacing in-vehicle can/lin bus - Google Patents

Abstract

The present invention discloses a wired communication system for replacing in-vehicle CAN/LIN bus. The wired communication system has a power line or a transmission line coupled to a plurality of communication units. The wired communication system includes: a main control communication unit; wherein, in a first time domain, each of the communication units has a transmission frequency band, and the transmission frequency bands between these communication units will not overlap with each other, and the transmission frequency band between the communication units does not overlap with the transmission frequency band or a transmission time of the main control communication unit; and all the transmission frequency bands can be combined into a complete OFDM frequency band, there is no guard band between the transmission frequency bands.

Description

Replace the wired communication system of CAN/LIN bus in the car

The present invention relates to a new wired communication system, which is used to replace the CAN/LIN bus-based architecture in the vehicle to reduce costs and improve the feasibility of automated production. The related method can also be applied to wired communication applications such as power lines or twisted pair or coaxial cables in the vehicle.

At present, the internal IoT network of vehicles is mostly based on "Controller Area Network" (CAN) and "Local Interconnect Network" (LIN) wiring, and then cooperates with other terminal control lines to complete the whole vehicle monitoring and communication; because these wiring harness materials are expensive, the wiring harness will increase the weight of the vehicle, reduce the effective space in the vehicle, and it is not easy to automate assembly and online upgrade. Therefore, if the power wires in the vehicle or fewer wiring harnesses can be used as the transmission lines in the vehicle for in-vehicle communication, it can achieve the advantages of reducing costs, reducing the overall weight of the system, increasing the effective space of the vehicle, and making it easy to upgrade the vehicle software and easy to automate production.

The existing PLC (Power Line Communication) protocols, such as G3-PLC (Generation 3 PLC), HPLC (High speed PLC) or Homplug AV/GreenPhy, all use fixed frequency bands for transmission. Among the many communication units on the same transmission line, only one communication unit can send the signal to the transmission line at the same time, otherwise the so-called signal "collision" will occur, causing signal errors and requiring retransmission. In other words, the existing PLC communication mode cannot guarantee that the signal transmission will be successful at one time. The existing PLC communication mode has the probability of error, and the time for successful completion of the transmission cannot be guaranteed. Since in-vehicle communication usually requires real-time reliability, the existing PLC communication protocol is not suitable for replacing the reliable CAN/LIN to complete the transmission.

In order to avoid collisions, frequency division multiplexing (FDM) was often used in the past to divide the available frequency bands into several frequency bands; and in order to prevent signals on different frequency bands from interfering with each other, a certain guard band must be left between frequency bands to avoid interference between adjacent frequency bands and ensure isolation between frequency bands. However, this method means that some frequency bands must be abandoned and used as guard bands. When we want to further divide the frequency bands into more frequency bands, the proportion of abandoned frequency bands becomes non-negligible, and the precious limited communication frequency bands cannot be fully utilized. In addition, in order to achieve better reception, various analog and digital filters are added to the hardware design of the communication unit for each frequency band, thereby increasing system cost and power consumption.

In order to ensure that each communication unit in the car has sufficient bandwidth, a fixed frequency band can be set for each communication unit. Compared with the common FDM device, the present invention does not need a guard band or an additional filter to complete the frequency band segmentation. The demodulation is also different from the common FDM device that demodulates its own exclusive frequency band. This invention demodulates the frequency band used by all communication units, and the packet length sent by all communication units is the same. The present invention discloses a method for replacing the CAN/LIN in the car. A wired communication system with a bus, the wired communication system has a power line or a transmission line (in one embodiment, for better communication quality, twisted pair cables or coaxial cables can also be used to replace the power line) and coupled with multiple communication units, the wired communication system includes: a main control communication unit, which is used to calibrate a time delay or an attenuation value of the communication units and complete clock calibration; wherein the main control communication unit is time synchronized with the communication units, the main control communication unit allocates multiple transmission frequency bands used by the communication units, and the main control communication unit adjusts the transmission energy of the communication units so that the transmission energy of the communication units corresponding to the attenuation of the transmission frequency bands is appropriately or correspondingly compensated. In some cases, compensation for attenuation can also be accomplished through receiver compensation.

An embodiment of the present invention discloses that the master communication unit allocates the communication units so that the communication units have an uplink time or a downlink time corresponding to the transmission frequency bands.

An embodiment of the present invention discloses that when the time delay and the attenuation value are greater than a critical value, after the master communication unit completes the allocation of the uplink time corresponding to the transmission frequency band to the communication units, the communication units simultaneously transmit the packet to the master communication unit, and the master communication unit forwards the packet to the target communication units. At this time, the master communication unit coordinates the transmission time of each communication unit and corrects the clock, so that the packet synchronization of each communication unit when transmitting the packet to the master communication unit is improved, or a better demodulation effect is obtained by correcting the angle of individual frequency bands at the receiving end in the system.

An embodiment of the present invention discloses that the master control communication unit compensates the signal energy of the communication units in advance before transmitting the packet according to the positions of the communication units on the power line or the attenuation value of the signal, so that when the target communication units receive the packet, the signal energy in all the transmission frequency bands is roughly the same. In addition, the receiving end in the system can also complete part or all of the compensation to demodulate the correct signal content.

An embodiment of the present invention discloses that, for the sake of cost reduction, certain communication units can transmit and receive fewer subcarriers of orthogonal frequency-division multiplexing (OFDM) or can carry fewer bits per frequency point. Through the arrangement of the master communication unit, different communication units can be mixed in the entire system to reduce the cost of the entire system.

The present invention discloses several architectures that can be used for in-vehicle wired communication (wires such as twisted pair or coaxial cable are also applicable, in which case the wire does not bear the role of power supply, is not connected to the battery, and is purely used for communication). This architecture is suitable for short-distance, low-noise, and small line impedance variation transmission line applications.

Please refer to FIG. 1, which shows a schematic diagram of an embodiment of the present invention. The present invention discloses a wired communication system 100 that replaces the CAN/LIN bus in a vehicle. The wired communication system 100 includes a main control communication unit 1, a plurality of application modules 101-10N, wherein each application module 101-10N has a corresponding communication unit 201-20N. The wired communication system 100 has a transmission line and is coupled to the communication units 201-20N. The wired communication system 100 is a non-power line communication system.

In order to avoid signal "collision" in the present invention, the communication units 201-20N can transmit in different frequency bands. In one embodiment, the communication units 201-20N are assigned different transmission frequency bands B1-BN, so the present invention does not have the problem of signal collision.

In one embodiment, assuming that the wired communication system 100 is in the first time domain, if the length of the power line or transmission line is relatively small relative to the wavelength of the transmission signal frequency band, then when the attenuation and delay of the signal received at any position on the power line or transmission line are very close, for example, less than a critical value, the system can be regarded as the same OFDM system; however, the frequency band that each communication unit can send is composed of certain non-repeating specific sub-carriers, and the system only needs to synchronize each The time and packet length of the communication unit sending the signal, then each communication unit can send the signal to its own dedicated frequency band at the same time, and at the same time receive the signals sent by all communication units and perform packet demodulation, that is, the transmission frequency bands between the communication units will not overlap with each other, and the communication units will not overlap with the transmission frequency band of the master communication unit or the transmission time; and all the transmission frequency bands can be combined into a complete OFDM frequency band, and there is no protection band between the transmission frequency bands. In such a system, since each communication module can demodulate the transmission content of other communication units, its communication mode is "many-to-many". As long as the transmission object of the message is specified in the transmission content, the receiver can know that the message is for itself and perform corresponding processing; and since all messages are demodulated, any communication unit will also know the content of the message exchanged between other communication units. This feature is very efficient for a highly intelligent autonomous driving system in the future. Any actuator can instantly grasp the information of other sensors or know the reactions of other actuators. Let's take a simple example to illustrate: suppose an OFDM system with sixty-four subcarriers is used as an example, as shown in FIG3 , there are sixteen communication units 201 to 2016 on the same power line that can communicate with each other, and each communication unit is allocated a dedicated frequency band of four subcarriers to send signals, then each communication unit can simultaneously use its own dedicated frequency band to send signals to other communication units for reception. For example, within a specific packet time, communication units 201, 205, 2010, and 2016 all sent packets. Communication units 201 and 205 both sent packets to communication unit 208, communication unit 2010 sent packets to communication unit 2016, and communication unit 2016 broadcasted to all other communication units. After all communication units received and demodulated the packets, communication unit 208 received packets from communication units 201 and 205, and communication unit 2016 received messages from communication unit 2010. In addition, communication units 201~2015 will receive packets from communication unit 2016. Because each communication unit will demodulate all packets output to the power line, each communication unit can also know all packets between each other. In this case, the master communication unit may be any one of the communication units 201-2016, which is responsible for coordinating the start of communication and for each communication unit 201-2016 to synchronously send and receive signals during the communication process.

In order to maintain a high overall transmission rate on the power line, each communication unit 201~20N can send and receive signals at the same time. However, in order for the signals sent by different communication units 201~20N to not become noise for other communication units 201~20N, the start and end time of the packets sent by each communication unit 201~20N must be synchronized when demodulated at the receiving end, so that the correct packet can be demodulated. That is to say, the system of the present invention must have a synchronization process after startup, and during normal operation, this synchronization must be maintained and reasonably fine-tuned to compensate for the influence of external factors such as temperature and humidity. In other words, the master communication unit must maintain all communication units continuously synchronized with its own clock, and the master communication unit and the communication unit simultaneously send packets of the same length, so that all signals can always be demodulated by each communication unit and the PLC master unit.

If the length of the transmission line corresponding to the wavelength of the communication frequency band is not very small, then the time delay between the signals sent by different communication units to each other may not be negligible, resulting in each communication unit no longer being able to correctly decode all OFDM signals, because the difference in signal arrival time may cause the signal to be distorted or interfered, thereby affecting the demodulation result. In this case, only the second transmission mode can be adopted: that is, all communication units only perform delay and attenuation correction on the master communication unit. Each communication unit still has a dedicated transmission frequency band and sends signals synchronously with the corrected time difference, but the object of all communication units transmitting messages is the master communication unit, which is a "one-to-many" communication mode. In this case, the communication units farther away from the master communication unit will start sending packets earlier, while those closer will start sending packets later. After correction, the OFDM signal received by the master communication unit is as if all transmission frequency bands are sent by a certain communication unit at the same time, and can be demodulated smoothly. In other words, the master communication unit adjusts the sending ends of all communication units in the system to perform time delay correction, so that when the packets sent by each communication unit reach the master communication unit, all packets can be combined into a complete OFDM signal. The transmission of messages will become a period of time when the communication unit sends signals to the master communication unit, and another period of time when the master communication unit sends messages to all communication units. In other words, the communication units separate signals with each other in the FDM method, and the communication units and the master communication unit separate signals with the time-division multiplexing (TDM) method to avoid collision. If communication unit 201 wants to send a message to communication unit 202, communication unit 201 must first send it to master communication unit 1, and then master communication unit 1 will send it to communication unit 202 in the subsequent message transmission period. To further explain, the master communication unit 1 is used to perform a time delay or attenuation correction on the communication units 201~20N to synchronize the time of all the communication units 201~20N; the master communication unit 1 also allocates the transmission frequency bands used by the communication units 201~20N; and the master communication unit 1 adjusts the transmission energy of the communication units 201~20N so that the energy value of the transmission energy of the communication units 201~20N corresponding to the transmission frequency bands B1~BN has been corrected when it reaches the master communication unit 1; or it is compensated by itself at the receiving end of the system, so that the information of all the communication units 201~20N can be demodulated smoothly. When the master communication unit 1 sends a signal, all communication units 201~20N are in receiving mode. At this time, the communication units 201~20N will not send any signal. Therefore, the master communication unit 1 can send signals in the full frequency band. All communication units 201~20N can demodulate all messages sent by the master communication unit 1, so the whole vehicle has an advantage in information sharing and can respond earlier.

In one embodiment, the master communication unit 1 allocates the communication units 201-20N so that the communication units 201-20N have an uplink time corresponding to the transmission frequency bands B1-BN to transmit a packet.

After the master communication unit 1 has allocated the uplink time corresponding to the transmission frequency bands B1-BN of the communication units 201-20N, the communication units 201-20N simultaneously transmit packets to the master communication unit 1, and the master communication unit 1 allocates the downlink time, and the master communication unit 1 transmits packets to the communication units 201-20N during the downlink time. That is, after the master communication unit has allocated the uplink time corresponding to the transmission frequency bands of the communication units, the communication units 201-20N simultaneously transmit their respective packets to the master communication unit 1 during the uplink time, and the master communication unit 1 demodulates the packets sent by all the communication units 201-20N to combine them into a complete OFDM signal, and the master communication unit 1 sends packets to the communication units 201-20N during the downlink time. In addition, when the master communication unit 1 transmits the packet, the communication units 201-20N are in a receiving state; and when the communication units 201-20N transmit the packet, the master communication unit 1 is in a receiving state.

In addition, after the initial startup of the wired communication system 100, the master communication unit 1 adjusts the delay and attenuation correction of each communication unit so that all signals in the transmission frequency bands B1-BN can reach the master communication unit at the same time and the unit energy size is roughly the same. Please refer to FIG. 2 at the same time, which shows a schematic diagram of the initial startup of the wired communication system 100 of the present invention. At this time, each communication unit 201~20N is in a different frequency band and has a different transmission power. Because each communication unit 201~20N is in a different position, the attenuation amount will also be different, so the main control communication unit 1 allows each communication unit 201~20N to perform pre-energy compensation so that when the receiving end of the system receives the signal, the energy level of the entire communication frequency band is consistent. Please refer to FIG. 3 at the same time. Assuming that there are sixteen communication units 201~2016 on the same power line that can communicate with each other, each communication unit is allocated a dedicated frequency band of four sub-carriers to send signals. FIG. 3 shows that the energy level of the communication unit 20N in the entire communication frequency band is consistent. In one embodiment, the attenuation correction can also be compensated by the receiving end of the main control communication unit 1.

In practical applications, the above concepts can be extended to other complex or mixed modes. For example, in order to use the communication channel more effectively, some application modules that are less sensitive to time delays (such as light dimming or window lift control) can use the same frequency band by multiple communication units, but they need to be used in time-sharing. In this way, the system can reserve a larger bandwidth for communication units with large data volumes or high real-time requirements. In addition, in order to enable specific high-rate and low-rate applications to operate at a lower cost, assuming that the wired communication system 100 is in a second time domain, in addition to the main control communication unit, other communication units in the system can also use full-band communication (or all transmission bands). For example, the image transmission of each camera is allocated time in TDM mode to allow data to be transmitted back to the main control communication unit, and the OFDM modulation and demodulation capabilities of low-bandwidth communication units such as connected lighting control or window control can be downgraded, that is, the accuracy and efficiency of OFDM signal processing of the low-bandwidth communication unit can be reduced to reduce the cost of the entire system. In one embodiment, the master communication unit modulates and demodulates 256 OFDM subcarriers, each of which supports 1024 quadrature amplitude modulation (QAM), that is, 1024 different discrete states can be transmitted in each signal cycle. The system connects 4 full-band high-speed communication units and 128 low-speed communication units. Each low-speed communication unit can only modulate and demodulate 16 consecutive subcarriers, and each subcarrier can only decode 64 QAM. The master communication unit can set the first packet time to be sent by the master communication unit, and the second to fifth packets are sent by the four high-speed communication units in turn (256 subcarriers can be sent, and each subcarrier can decode 1024 QAM). The sixth packet is allocated to 16 low-speed communication units, and each low-speed communication unit is assigned to use 16 non-repeating consecutive subcarriers. Similarly, the seventh to 13th packets are all assigned to 16 non-repeating low-speed communication units. That is, 128 low-speed communication units are allocated to 8 packets to send a message in turn. Then the master communication unit takes turns to send the message, and this is repeated; that is, in each signal cycle, the packet time used by the master communication unit and the high-speed communication unit is interspersed with the packet time of the low-speed communication unit, so each communication unit has its own exclusive and fixed transmission frequency band and message volume. For such a system, since the subcarrier modulation capability of the low-speed communication unit is only 64 QAM, its signal-to-noise ratio (SNR) requirement for the transmission signal is lower, that is, the reliability is higher. However, since its demodulation capability is only 16 subcarriers, the master communication unit must place the message in its configured subcarrier and the most significant bit (MSB) 8 bits to send a message to the low-speed communication unit. There is no limit to the messages that the master communication unit can send to the high-speed communication unit.

When the present invention is applied to in-vehicle communication, the communication wire can use better dedicated wires such as twisted pair or coaxial cable to improve the communication quality. However, if the power line connected to the battery and the power supply to each in-vehicle application module 41N is used to reduce costs, in order to ensure the communication quality, each communication unit 201~20N must be equipped with a low-pass filter 401 and a coupler 402 that bypasses the low-pass filter 401 to transmit the signal to the power line trunk. Please refer to Figure 4A, which shows a schematic diagram of an embodiment of the wired communication system 400A of the present invention that replaces the in-vehicle CAN/LIN bus. In addition, a low-pass filter F should also be connected in series between the battery BA and the power line. Its main purpose is to ensure that the signal in the communication frequency band will not be greatly attenuated due to the low impedance of the battery BA and the power unit, and it can also prevent the noise generated by the power unit from entering the power line trunk channel. Among them, the wired communication system 400A is a communication system using power lines.

In addition, since the vehicle's ground wire is generally replaced by the vehicle body, DC power is generally supplied to each application module by the power cord (live wire), and then the DC power flows back to the battery from the vehicle body ground wire. If the network signal also takes the same loop, it is easy to radiate the signal, and the external interference noise is also easily absorbed by the transmission line. Therefore, it is more appropriate to use twisted pair wires for differential signal transmission. In other words, the DC current loop still inherits the original vehicle body loop, but the network signal returns through the twisted pair loop. At this time, the differential signal transmission line can be used as the same set of DC power lines or two sets of power lines (for example, one is 3.3V and the other is 24V), which can also appropriately reduce the demand for power chips on each application module.

In the power line embodiment, the coupler generally uses a resistor in series with a capacitor or a transformer to isolate the voltage on the power line and can transmit and receive full-channel information, as shown in FIG5 .

As mentioned above, in each application module 411~41N of the wired communication system (power line) 400A, each application module 411~41N includes a power unit 301~30N and its corresponding communication unit 201~20N, that is, the vehicle's main control communication unit 1 transmits power energy waves and network signals through the vehicle power line, and the low-pass filter 401 is set at the power end E entrance of each or part of the application modules 411~41N of the device 400A to pass The network signal is filtered to allow the power energy wave to enter the power consumption units 301-30N of the application modules 411-41N; the coupler 402 is used to generate a coupling path P1, and the coupling path P1 is used to provide the network signal without passing through the low-pass filter 401, and enter the transmission end T through the first coupler 402 through the coupling path P1; that is, the network signal enters the communication unit 201-20N in the application module 411-41N through the coupling path P1 generated by the coupler 402. Among them, the power consumption unit 301-30N is the power supply unit corresponding to the communication unit.

Please note that the low-pass filter 401 is disposed at the entrance of each or part of a power terminal E of the wired communication system 400A. The low-pass filter 401 separates the power line into the power terminal E and the transmission terminal T. The power line impedance on the transmission terminal T side will not be affected by the power terminal E side.

Please refer to FIG. 4B, which shows a schematic diagram of an embodiment of the wired communication system 400B that replaces the in-vehicle CAN/LIN bus of the present invention. The difference between the wired communication system 400B that replaces the in-vehicle CAN/LIN bus and 400A is that the present embodiment can use an active isolator 403 to replace the low-pass filter to reduce the requirements for the transformer or inductance value; in other words, the active isolator 403 is set at the entrance of each or part of a power terminal E of the wired communication system. The active isolator 403 separates the power line into the power terminal E and the transmission terminal T, and is used to filter the network signal so that the power energy wave enters the power terminal E. The rest of the principle is the same as above.

Please refer to FIG. 4C , which shows a schematic diagram of an embodiment of an active isolator 403. The isolator of this embodiment includes two transformers K1 and K2, which are respectively connected in series to the power line; and two amplifiers A1 and A2, which are respectively coupled to the starting end of the primary coil and the starting end of the secondary coil of the transformer K1, and the output end of the amplifier A1 is coupled to the inverting input end of the amplifier A1, the output end of the amplifier A2 is coupled to the inverting input end of the amplifier A2, and the output ends of the amplifiers A1 and A2 are coupled between the two transformers K1 and K2; the positive terminals of the amplifiers A1 and A2 are connected to the positive terminals of the amplifiers A1 and A2. The phase input end is respectively coupled to the starting end of the primary coil or the starting end of the secondary coil of the transformer K1; a high-voltage capacitor C is connected in parallel to the power line on the high-voltage side, that is, the high-voltage capacitor C is connected in parallel to the terminal of the primary coil of the transformer K2, the terminal of the secondary coil and the power line; and the capacitor C is connected in parallel between the starting end of the primary coil or the starting end of the secondary coil of the transformer K1, the positive phase input end of the amplifiers A1 and A2 and the power line, and the terminal of the primary coil or the terminal of the secondary coil of the transformer K1, the inverting input end and the output end of the amplifiers A1 and A2 and the power line.

In addition, whether a power line or a better independent transmission line is used as the in-vehicle transmission line, the impedance of the transceiver must be consistent, and a specific structure is required, such as the transceiver circuit of the communication unit 201~20N shown in Figure 5. In this embodiment, the communication unit 201~20N includes two capacitors C; and two matching resistors Rs, which are connected in series with the capacitors C respectively as impedance matching; wherein a line driver LD (line driver) is set between the transmission end Tx of the communication unit and the matching resistor Rs, and a low noise amplifier LNA is set between the receiving end Rx of the communication unit, the capacitor C, and the matching resistor Rs. Among them, the matching resistor RS is connected in series with the capacitor C as impedance matching, and the transmission end Tx is connected in parallel with a switch S. When the transmission end Tx signal is sent, this switch S is open circuit; when the transmission end Tx signal is not sent, this switch S is short circuit. If N communication units are connected to the power line and the low-frequency impedance of the transmission line is much smaller than the matching resistor and the transmission frequency band wavelength is much larger than the length of the transmission line, then the signal sent by the line driver LD on each communication unit will be attenuated to 1/(N+1) of the original after reaching the transmission line. If 99 communication units are set on the power line, the signal received by the receiving end Rx will be 1/100 of the superposition of the signals sent by all communication units, that is, 40dB attenuation.

In addition, since the vehicle's ground wire is generally replaced by the vehicle body, DC power is generally supplied to each application module by the power cord (live wire), and then the DC power flows back to the battery from the vehicle body ground wire. If the network signal also takes the same loop, it is easy to radiate the signal, and the external interference noise is also easily absorbed by the transmission line. Therefore, it is more appropriate to use twisted pair wires for differential signal transmission. In other words, the DC current loop still inherits the original vehicle body loop, but the network signal returns through the twisted pair loop. At this time, the differential signal transmission line can be used as the same set of DC power lines or two sets of power lines (for example, one is 3.3V and the other is 24V), which can also appropriately reduce the demand for power chips on each application module.

When some communication units have lower requirements for real-time performance and speed, multiple communication units can be connected to the same power line using the same frequency band. At this time, a more complex anti-collision mechanism is needed, for example: limiting different communication units using the same frequency band to transmit signals only at specific times.

For groups with the same high-frequency band, communication units can communicate with each other directly through specific protocols; while for groups with different high-frequency bands, communication units must communicate with each other through units equipped with transceivers of different frequency bands, such as the main control communication unit on the vehicle or other regional adapter boards to graft communication (as shown in Figure 6). FIG. 6 shows an approach similar to FIG. 4 , and is applicable to the aforementioned “one-to-many” or “many-to-many” communication mode. The wired communication system is coupled to the main control communication unit through different bandpass filters corresponding to different transmission frequency bands. The bandpass filters can filter signals of different frequency bands to the communication units in the communication unit group. The wired communication system has a plurality of transmission module groups corresponding to different transmission frequency bands B1~BN. Communication units that are not in the same transmission module group cannot communicate directly with each other, and the transmission frequency bands are also different. One embodiment is to use a low frequency band (e.g. 100KHz~2MHz) as a large frequency band (combined frequency band), and each communication unit 201~203 using this frequency band has its own exclusive transmission frequency band, and can directly send signals to each other and demodulate them in real time without forwarding through the main control communication unit. All signals of the communication units 201~203 using this large frequency band will be coupled to the transmission line through the 100KHz~2MHz bandpass filter. The other large frequency band (combined frequency band) is 10MHz~100MHz, and the communication units 204~20N using this large frequency band must communicate with each other through the main control communication unit. The input coupler is a 10MHz~100MHz bandpass filter or a 10MHz high-pass filter. A guard band must be reserved between the two large frequency bands to avoid mutual interference, and the main control communication unit has a transceiver that can send and receive multiple OFDM signals (not shown).

Please refer to FIG7. In some special applications, such as in-car communication, in order to increase the bandwidth, a low-pass filter can be added between different segments of the power line, and then a main control communication unit is added to connect them. The communication of different segments of the power line must be transmitted through this main control communication unit. The simplest way is to divide the main control communication unit into four lines, left, right, top and bottom. The principle is the same as the aforementioned FIG4. The difference is that low-pass filters are used to connect to the power supply Vs, and the main control communication unit has four groups of communication units 20N_1~20N_4 connected to each segment of the power line.

100: Wired communication system (non-power line) 400A: Wired communication system (power line) 400B: Wired communication system (power line) 401, F: Filter 402: Coupler 403: Active isolator P1: Coupling path 201~20N, 20N_1~20N_4: Communication unit 101~10N, 411~41N: Application module 301~30N: Power unit 1: Main control communication unit RS: Matching resistor C: Capacitor LNA: Amplifier LD: Line driver S: Switch TX: Transmitter RX: Receiver Vs: Power supply BA: Battery E: Power terminal T: Transmitter

[FIG. 1] shows a schematic diagram of a transmission line (non-power line) embodiment of the present invention. [FIG. 2] shows a schematic diagram of the initial startup of the wired communication system 100 of the present invention. [FIG. 3] shows the frequency bands to which the communication units 201-2016 are allocated in the entire communication frequency band in the OFDM embodiment of sixty-four subcarriers, and each frequency band has four subcarriers. [FIG. 4A] shows a wired communication system 400A of the present invention that replaces the in-vehicle CAN/LIN bus. [FIG. 4B] shows a wired communication system 400B of the present invention that replaces the in-vehicle CAN/LIN bus. [FIG. 4C] shows a schematic diagram of an active isolator 403. [FIG. 5] shows an embodiment of the transceiver circuit of the communication unit 20N. [Figures 6-7] show an embodiment of the present invention.

100: Wired communication system (non-power line)

101~10N: Application module

201~20N: Communication unit

1: Main control communication unit

Claims (21)

A wired communication system that replaces the CAN/LIN bus in a vehicle, the wired communication system has a power line or a transmission line and is coupled to a plurality of communication units, the wired communication system comprises: A master control communication unit, used to perform clock correction on the communication units to complete synchronization, or to perform correction of time delay or attenuation value; Wherein, in a first time domain, each of the communication units has a dedicated transmission frequency band, and the transmission frequency bands between the communication units do not overlap with each other, and the transmission frequency bands between the communication units do not overlap with the transmission frequency band or a transmission time of the master control unit; and, all the transmission frequency bands can be combined into a complete OFDM frequency band, and there is no guard band between the transmission frequency bands. A wired communication system as described in claim 1, wherein the master communication unit is time synchronized with the communication units so that the packets simultaneously sent by the communication units and the master communication unit can be combined into a complete OFDM signal, and the communication units and the master communication unit can receive and demodulate at the same time; the master communication unit is required to maintain continuous clock synchronization of all the communication units, and the master communication unit and the communication units simultaneously send packets of the same length so that all signals can always be demodulated by each of the communication units and the master communication unit. A wired communication system as described in claim 1, wherein the master communication unit allocates the communication units so that the communication units have corresponding exclusive transmission frequency bands; the master communication unit can use the transmission frequency bands used by all the communication units; the master communication unit allocates an uplink time to the communication units to transmit packets, and the master communication unit also allocates a downlink time to transmit packets to the communication units; the master communication unit adjusts the transmitting ends of all the communication units in the system to perform time delay correction, so that when the packets sent by each of the communication units arrive at the master communication unit, all packets can be combined into a complete OFDM signal. A wired communication system as described in claim 3, wherein, after the master communication unit allocates the uplink time corresponding to the transmission frequency band to the communication units, the communication units simultaneously transmit their respective packets to the master communication unit during the uplink time, and the master communication unit demodulates the packets sent by all the communication units to combine them into a complete OFDM signal, and the master communication unit sends packets to the communication units during the downlink time. A wired communication system as described in claim 4, wherein when the master communication unit transmits the packet, the communication units are in a receiving state; and when the communication units transmit packets, the master communication unit is in a receiving state. A wired communication system as described in claim 1, wherein the master communication unit has a transceiver that can transmit and receive multiple OFDM signals, and the wired communication system is coupled to the master communication unit through a bandpass filter corresponding to different transmission frequency bands, wherein the communication units in the wired communication system cannot communicate directly with each other, but all of the communication units can communicate with the master communication unit simultaneously. A wired communication system as described in claim 2, wherein each of the communication units comprises: two capacitors; and two matching resistors, each of which is connected in series with a capacitor for impedance matching; wherein a line driver is provided between a transmitting end of the communication unit and the matching resistors, and a low noise amplifier (LNA) is provided between a receiving end of the communication unit, the capacitors, and the matching resistors. A wired communication system as described in claim 5, wherein each of the communication units comprises: two capacitors; and two matching resistors, each of which is connected in series with a capacitor for impedance matching; wherein a line driver is provided between a transmitting end of the communication unit and the matching resistors, and a low noise amplifier (LNA) is provided between a receiving end of the communication unit, the capacitors, and the matching resistors. A wired communication system as described in claim 2, wherein the wired communication system has an electric energy wave and a network signal transmitted on the power line, and the wired communication system comprises: A first low-pass filter, disposed at the entrance of each or part of a power-using end of the wired communication system, the first low-pass filter separates the power line into the power-using end and a transmission end, and is used to filter the network signal so that the electric energy wave enters the power-using end; and A first coupler, used to generate a first coupling path, the first coupling path is used to provide the network signal without passing through the first filter, and the network signal enters the transmission end through the first coupling path through the first coupler; Wherein, the power line impedance on the transmission end side will not be affected by the power-using end side. A wired communication system as described in claim 5, wherein the wired communication system has an electric energy wave and a network signal transmitted on the power line, and the wired communication system comprises: A first low-pass filter, disposed at the entrance of each or part of a power-using end of the wired communication system, the first low-pass filter separates the power line into the power-using end and a transmission end, and is used to filter the network signal so that the electric energy wave enters the power-using end; and A first coupler, used to generate a first coupling path, the first coupling path is used to provide the network signal without passing through the first filter, and the network signal enters the transmission end through the first coupling path through the first coupler; Wherein, the power line impedance on the transmission end side will not be affected by the power-using end side. A wired communication system as described in claim 3, wherein the master communication unit adjusts the transmission energy of the communication units so that the signal energy in all the transmission frequency bands is approximately the same. A wired communication system as described in claim 1, wherein a plurality of communication units use the same transmission frequency band, but the communication units need to use the same transmission frequency band in a time-sharing manner. In the wired communication system as described in claim 1, a plurality of communication units may use the same transmission frequency band on the same power line, but different communication units using the same transmission frequency band may only transmit signals at specific times. A wired communication system as described in claim 1, wherein, in a second time domain, at least one of the communication units other than the master communication unit on the same power line uses all of the transmission frequency bands. A wired communication system as described in claim 14, wherein the wired communication system connects a plurality of high-speed communication units and a plurality of low-speed communication units; wherein the OFDM modulation and demodulation capabilities of the low-speed communication units are degraded. A wired communication system as described in claim 15, wherein in each signal cycle, the packet times used alternately by the master communication unit and the high-speed communication units are interspersed with the packet times of the low-speed communication units. A wired communication system as described in claim 16, wherein each low-speed communication unit is assigned to use non-repeating continuous sub-carriers. A wired communication system as described in claim 2, wherein the wired communication system has a power energy wave and a network signal transmitted on the power line, and the wired communication system comprises: an active isolator, arranged at the entrance of each or part of a power-using end of the wired communication system, the active isolator separates the power line into the power-using end and a transmission end, and is used to filter the network signal so that the power energy wave enters the power-using end; and a first coupler, used to generate a first coupling path, the first coupling path is used to provide the network signal without passing through the active isolator, and the network signal enters the transmission end through the first coupling path through the first coupler; wherein the power line impedance on the transmission end side will not be affected by the power-using end side. A wired communication system as described in claim 18, wherein the active isolator comprises: Two transformers, respectively connected in series to the power line; Two amplifiers, respectively coupled to the starting end of the primary coil and the starting end of the secondary coil of the first of the transformers, and the output ends of the amplifiers are respectively coupled to the inverting input ends of the amplifiers and between the two transformers; the non-inverting input ends of the amplifiers are respectively coupled to the starting end of the primary coil or the starting end of the secondary coil of the first of the transformers; A plurality of capacitors are respectively connected in parallel between the starting end of the primary coil or the starting end of the secondary coil of the first transformer, between the non-inverting input end of the amplifiers and the power line, and between the terminal end of the primary coil or the terminal end of the secondary coil of the first transformer, between the inverting input end and the output end of the amplifiers and the power line; and another capacitor is connected in parallel to the power line on the high voltage side. A wired communication system as described in claim 5, wherein the wired communication system has a power energy wave and a network signal transmitted on the power line, and the wired communication system comprises: an active isolator, arranged at the entrance of each or part of a power-using end of the wired communication system, the active isolator separates the power line into the power-using end and a transmission end, and is used to filter the network signal so that the power energy wave enters the power-using end; and a first coupler, used to generate a first coupling path, the first coupling path is used to provide the network signal without passing through the active isolator, and the network signal enters the transmission end through the first coupling path through the first coupler; wherein the power line impedance on the transmission end side will not be affected by the power-using end side. A wired communication system as described in claim 20, wherein the active isolator comprises: Two transformers, respectively connected in series to the power line; and Two amplifiers, respectively coupled to the starting end of the primary coil and the starting end of the secondary coil of the first of the transformers, and the output ends of the amplifiers are respectively coupled to the inverting input ends of the amplifiers and between the two transformers; the non-phase input ends of the amplifiers are respectively coupled to the starting end of the primary coil or the starting end of the secondary coil of the first of the transformers; A plurality of capacitors are respectively connected in parallel between the starting end of the primary coil or the starting end of the secondary coil of the first transformer, between the non-inverting input end of the amplifiers and the power line, and between the terminal end of the primary coil or the terminal end of the secondary coil of the first transformer, between the inverting input end and the output end of the amplifiers and the power line; and another capacitor is connected in parallel to the power line on the high voltage side.