A PLC router and its application in increasing the transmission distance of PLC medium frequency band data

Abstract

The present invention discloses a PLC router and its application in increasing the data transmission distance of the PLC medium frequency band, belonging to the field of power line carrier communication; the PLC router is located between two adjacent PLC networks, and includes: a power conversion circuit, a STA module, a CCO module, a PA circuit and an isolator; the power conversion circuit is connected to the STA module, the CCO module and the PA circuit through positive and negative power lines, and provides a DC regulated power supply, the STA module is connected to the previous PLC network through the power line, the STA module is connected to the CCO module through a serial port, the CCO module and the PA circuit are connected through a linear control line, and the CCO module is connected to the next PLC network through the power line; the isolator is serially connected to the power lines of the two previous and next PLC networks. The PLC router integrates logical units such as STA, CCO and PA, and realizes functions such as transmission signal enhancement and multi-segment signal isolation.

Description

Technical Field

[0001] The invention belongs to the field of power line carrier communication, and in particular relates to a PLC router and an application thereof in increasing the data transmission distance in a PLC medium frequency band. Background Art

[0002] The actual maximum transmission distance of the existing power line communication (PLC) technology in the medium frequency band (0.7M~12M) is about 1000 meters. If long-distance transmission is required, other network technologies are often used as transmission relays, such as Ethernet, optical fiber or wireless. However, in actual applications, due to unfavorable factors such as deployment environment restrictions, complex network construction, and high operation and maintenance costs, these technologies are greatly restricted in the application of PLC long-distance (10~20 kilometers) projects. For this reason, a PLC router is proposed. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a PLC router and its application in increasing the data transmission distance in the PLC mid-frequency band, thereby solving the problems in the prior art.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A PLC router is located between two adjacent PLC networks, comprising: a power conversion circuit, a STA module, a CCO module, a PA circuit and an isolator;

[0006] Among them, the power conversion circuit is connected to the STA module, CCO module, and PA circuit through positive and negative power lines, and provides a DC regulated power supply. The STA module is connected to the previous PLC network through the power line, the STA module and the CCO module are connected through a serial port, the CCO module and the PA circuit are connected through a linear control line, and the CCO module is connected to the next PLC network through the power line; the isolator is connected in series to the power lines of the front and rear PLC networks.

[0007] Furthermore, the power conversion circuit is an AC / DC circuit or a DC / DC circuit.

[0008] Furthermore, the STA module accesses the previous PLC network through the power line, receives the message sent by the previous PLC network, and sends the message that needs to be routed to the CCO module through the serial port for routing and forwarding processing; the STA module can also receive the network layer message sent from the serial port of the CCO module, encapsulate the link layer message header and send it to the previous PLC network.

[0009] Furthermore, the CCO module receives the message sent from the next PLC network, and after routing decision processing, sends the message that needs to be routed to the STA module through the serial port; the CCO module also receives the message sent from the serial port of the STA module, and after routing decision processing, sends the message that needs to be routed to the next PLC network.

[0010] Furthermore, the CCO module, as a network master node, establishes a PLC network and adopts a whitelist mechanism to set the MAC addresses of STA modules allowed to join the local PLC network into the CCO whitelist.

[0011] Furthermore, the PA circuit receives the linear signal control of the CCO module; the CCO module drives the PA circuit to enhance the transmission power of the PLC physical layer signal, improve the signal-to-noise ratio, and extend the communication distance of the PLC network.

[0012] Furthermore, the PA circuit includes a power amplifier chip and a coupler, which is connected to the CCO via a differential signal interface to transmit data signals, and is connected to the CCO via a linear signal interface to receive linear control signaling from the CCO.

[0013] Furthermore, the isolator includes an inductor and a capacitor, which are connected in series to the power lines of the front and rear sections of the PLC network to isolate the carrier signals of the two sections of the power lines and other interference signals from the link.

[0014] The above-mentioned PLC router is used to increase the data transmission distance in the PLC mid-frequency band.

[0015] A PLC networking includes multiple PLC networks, and the above-mentioned PLC router is arranged between two adjacent PLC networks.

[0016] Beneficial effects of the present invention:

[0017] 1. The PLC router of the present invention integrates CCO and STA functions. CCO and STA realize data transparent transmission through the serial port interface of the PLC chip. In addition, CCO adopts PA technology to enhance the CCO signal transmission strength and improve the communication capability of the local PLC network.

[0018] 2. The present invention adds an isolator between CCO and STA to prevent signal interference and communication channel competition between multiple PLC networks.

[0019] 3. The CCO of the present invention adopts a whitelist mechanism to set the MAC address of the STA allowed to join the local PLC network into the whitelist of the CCO, which can accelerate the networking speed of the PLC network and prevent signal crosstalk between multiple PLC networks from the link layer.

[0020] 4. The CCO of the present invention adds a network layer message routing and forwarding mechanism. The IEEE1901.1 international standard only defines the physical layer and the link layer. Messages are forwarded in the local PLC network using the link layer address (i.e., a 6-byte MAC address). In order for messages to be automatically routed and forwarded across multiple PLC networks and eventually reach their destination, it is necessary to define a network layer above the link layer. All PLC nodes participating in PLC network layer communications need to be set with a globally unique network layer address (i.e., a 2-byte network address). Nodes with message routing and forwarding capabilities (PLC routers) need to be configured with a static routing table and be able to query the routing table for message routing and forwarding.

[0021] 5. The present invention applies PLC routers to PLC networking, and increases the transmission distance of the PLC network by adding PLC router nodes on the power lines without introducing new network types or laying new communication lines. This is feasible from both the economic and technical levels, whether it is new construction or renovation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a schematic diagram of the logical framework of the PLC router of the present invention;

[0024] Figure 2 It is a schematic diagram of the PLC networking structure with a PLC router in the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to realize data communication on long-distance power lines (such as 20 kilometers), the power line can be divided into multiple (such as 20) segments of approximately equal length, each segment constructs a PLC network, and a PLC router is set between two adjacent PC networks for connection.

[0027] And because the power line is an extremely unstable transmission channel with high noise and strong attenuation, many complex factors must be solved to achieve reliable and stable long-distance data communication, including various noises and signal attenuation, channel competition and signal crosstalk between multiple PLC networks, data message routing, etc. For this purpose, the following are set up: Figure 1 The PLC router shown.

[0028] like Figure 1 As shown, the PLC router includes: AC / DC circuit, STA (Station) module, CCO (Central Coordinator) module, PA (Power Amplifier) ​​circuit and isolator;

[0029] Among them, the AC / DC circuit is connected to the STA module, CCO module, and PA circuit through the positive pole (3.3v) and the negative pole (ground wire). The STA module is connected to the previous PLC network through the power line, the STA module and the CCO module are connected through the serial port, the CCO module and the PA circuit are connected through the linear control line, and the CCO module is connected to the next PLC network through the power line; the isolator is connected in series to the power lines of the front and rear PLC networks.

[0030] 1) AD / DC circuit

[0031] The AC / DC circuit provides a stable and compliant DC regulated power supply for the STA module, CCO module, and PA circuit; in other embodiments, the DC / DC circuit can also provide a stable and compliant DC regulated power supply for the STA module, CCO module, and PA circuit.

[0032] In this embodiment, the AC / DC circuit includes an input protection circuit, an EMI filter, an input rectifier filter circuit, a transformer, a flyback control circuit, an output rectifier filter circuit, a linear voltage regulator circuit, etc. The 50Hz AC voltage is rectified and filtered to obtain a DC high voltage, and then a stable and efficient high voltage is output after the flyback control circuit and the rectifier filter processing, and finally a stable and compliant DC regulated power supply is obtained after the transformer and the linear voltage regulator processing.

[0033] 2) STA module

[0034] The STA module accesses the previous PLC network through the power line, receives the messages sent by the previous PLC network, and sends the messages that need to be routed to the CCO module through the serial port for further routing and forwarding processing; at the same time, it can also receive the network layer messages sent from the CCO module serial port, encapsulate the link layer message header and send it to the previous PLC network.

[0035] 3) CCO module

[0036] The CCO module accesses the next PLC network through the power line and establishes the PLC network as the main node of the network. The whitelist mechanism is used to control which STAs can join the network. The MAC addresses of the STA modules allowed to join the local PLC network are set to the CCO whitelist. This can speed up the networking speed of the PLC network and prevent signal crosstalk between multiple PLC networks from the link layer.

[0037] The CCO module receives the message sent by the next PLC network, and after the routing decision is processed, the message that needs to be routed is sent to the STA module through the serial port. At the same time, the CCO module also receives the message sent by the STA module serial port, and after the routing decision is processed, the message that needs to be routed is sent to the next PLC network.

[0038] 4) PA circuit

[0039] The PA circuit is connected to the CCO module through a linear control line and accepts the linear signal control of the CCO module; the CCO module drives the PA to enhance the transmission power of the PLC physical layer signal, improve the signal-to-noise ratio, and extend the communication distance of the PLC network.

[0040] In this embodiment, the PA circuit includes a power amplifier chip and a coupler. The power amplifier receives a differential data signal sent from the CCO and enhances the data signal under the control of the CCO linear signal. The enhanced signal is output to the coupler and coupled to the power line.

[0041] 5) Isolator

[0042] The isolator is used to isolate the front and rear PLC networks to reduce signal interference and channel contention between the networks.

[0043] In this embodiment, the isolator includes an inductor and a capacitor, which are connected in series to the power lines of the front and rear PLC networks to isolate the two PLC signals from the link and prevent signal crosstalk.

[0044] PLC networking with PLC router Figure 2 As shown, the message routing forwarding decision of the PLC router of the present invention implements the following network layer technology:

[0045] 1) Network layer message header definition:

[0046] The IEEE1901.1 international standard defines the PLC link layer and physical layer. PLC nodes implement message transmission based on the MAC address of the link layer message header. When messages need to be transmitted remotely across the local network, a higher-level network layer message header format and network address need to be defined.

[0047] The network layer message header format is shown in Table 1 below:

[0048] Table 1 Network layer message header format

[0049]

[0050] Among them, Dst Addr (destination network address): the destination address of the message, which can be a unicast, broadcast or multicast address.

[0051] Src Addr (source network address): the unicast address of the node that sends the message.

[0052] Ver (version number): The current version is 0x01, which is used for protocol version compatibility.

[0053] Ctrl (control field): bit0: 0 indicates normal message; 1 indicates node network address announcement; bit1~bit7: reserved.

[0054] Len (application layer message length): The maximum length of the application layer message is 488.

[0055] Data is the application layer message data.

[0056] The network address must be uniformly coded throughout the network. In the PLC network, the network layer message receiving end point (STA, CCO) needs to be configured with a network address that is unique to the entire network. The PLC router, which serves as a message routing relay, has two PLC link interfaces, so each link interface needs to be configured with a network address. The network address pre-allocation is shown in Table 2:

[0057] Table 2 Network address allocation table

[0058] Network Address definition 0x0000 reserve 0xFFFF Network-wide broadcast address 0xFFFE Local broadcast address 08000~0x80FF Multicast Address 0x4000~6FFF Unicast Address 0x1000~1FFF Local unicast address Other Addresses Reserve

[0059] 2) Routing table definition:

[0060] After the PLC routing node receives the network layer message, it needs to search the routing table according to the destination address in the message header to locate the next node to which the message needs to be delivered.

[0061] The routing table format is shown in Table 3 below:

[0062] Table 3 Routing table format example

[0063]

[0064] Among them, the destination network address: a legal unicast address format that complies with the pre-allocation agreement of the network address space

[0065] Destination network address mask: 2-byte bit value (0 / 1) mask string. When searching for routes, the 2-byte destination network address is compared bit by bit from left to right. If the corresponding bit mask value is 0, it will not be compared (the bit is equal by default). The benefit of introducing the network address mask is: if the PLC network address is allocated from right to left in a planned manner, the left side of the network address of all nodes in the same PLC network is the same, so the routes of all nodes in the network are aggregated into only one routing table entry in the routing table, which greatly simplifies routing table management and routing search.

[0066] Next-hop node MAC address: The 6-byte MAC address of the node closest to the destination network address in the local PLC network.

[0067] The defined longest power line distance is 20 kilometers, so the maximum number of PLC networks is 20. Even if routing table aggregation is not used, the maximum number of routing tables that need to be specified is 20. Since the number is not large, the static routing table of CCO can be manually configured.

[0068] STA with network layer capability does not need to manually configure the routing table, it uses the automatically generated default route. After the STA node with network layer capability is powered on and successfully connected to the PLC network led by CCO, it will actively send network address announcement broadcast messages every second. The destination of the network address announcement message header is filled with 0xFFFF, and the source address is filled with the pre-configured network address. Until the network address announcement message sent by CCO is received, the STA node regards the CCO network address announcement message as a response and automatically generates a default route (the destination network address and the destination network address are both 0x0000). The role of the default route is to use the default route to forward the message to the CCO node of the local PLC network when the corresponding routing table entry is not found during message routing forwarding, and the CCO node will perform further routing forwarding processing.

[0069] In the same PLC network, the application layer can directly use the link layer to transmit messages, or it can use the network layer to transmit messages.

[0070] When CCO receives the network address announcement message actively sent by the STA node after joining the network, it will automatically generate a routing table entry for the STA node. The destination network address mask in the entry is set to 0xFFFF. Subsequent network layer messages sent by CCO to the STA will use this routing table entry for routing forwarding.

[0071] There are no routing entries between STA nodes to each other. When network layer messages are sent, they can only be forwarded by CCO nodes through the default route. This also complies with the definition of link layer message transmission behavior in the IEEE1901.1 international standard.

[0072] 3) Routing and message encapsulation:

[0073] When the network layer of the PLC node receives a message sending request with a network layer message header delivered by the application layer, it uses the destination network address in the message header to search the routing table and obtain the corresponding routing table entry. If the corresponding routing table entry is not found, the default route (if it exists) is used as the routing table entry, and then the MAC address of the next hop node is taken from the routing table entry, and the link layer message header is encapsulated according to the IEEE1901.1 international standard, and delivered to the link layer for further link layer message transmission.

[0074] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0075] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A PLC router, characterized in that: Located between two adjacent PLC networks, including: power conversion circuit, STA module, CCO module, PA circuit and isolator; The power conversion circuit is connected to the STA module, the CCO module, and the PA circuit through positive and negative power lines, and provides a DC regulated power supply. The STA module is connected to the previous PLC network through the power line, the STA module is connected to the CCO module through a serial port, the CCO module and the PA circuit are connected through a linear control line, and the CCO module is connected to the next PLC network through the power line; the isolator is connected in series to the power lines of the front and rear PLC networks; The STA module accesses the previous PLC network through the power line, receives the message sent by the previous PLC network, and sends the message that needs to be routed to the CCO module through the serial port for routing and forwarding processing; the STA module can also receive the network layer message sent from the CCO module serial port, encapsulate the link layer message header and send it to the previous PLC network; The CCO module receives the message sent by the next PLC network, and after the routing decision processing, sends the message that needs to be routed to the STA module through the serial port; the CCO module also receives the message sent by the serial port of the STA module, and after the routing decision processing, sends the message that needs to be routed to the next PLC network; The CCO module, as the main network node, establishes a PLC network and adopts a whitelist mechanism to set the MAC address of the STA module allowed to join the local PLC network into the CCO whitelist; The PA circuit receives the linear signal control of the CCO module; the CCO module drives the PA circuit to enhance the transmission power of the PLC physical layer signal, improve the signal-to-noise ratio, and extend the communication distance of the PLC network; The PA circuit includes a power amplifier chip and a coupler, which is connected to the CCO module through a differential signal interface to transmit data signals, and is connected to the CCO module through a linear signal interface to receive linear control signaling from the CCO module; The isolator includes an inductor and a capacitor, which are connected in series to the power lines of the front and rear sections of the PLC network to isolate the carrier signals of the two sections of the power lines and other interference signals from the link.

2. A PLC router according to claim 1, characterized in that: The power conversion circuit is an AC / DC circuit or a DC / DC circuit.

3. Application of a PLC router as described in claim 1 or 2 in increasing the data transmission distance in the PLC mid-frequency band.

4. A PLC network, comprising a plurality of PLC networks, characterized in that: A PLC router as claimed in claim 1 or 2 is arranged between two adjacent PLC networks.

Images