A communication method of a broadband carrier communication network

Abstract

A communication method of a broadband carrier communication network, a table box relay broadband carrier communication module capable of three-phase communication is arranged at the line entrance of each table box, any two nodes with three-phase communication capability in the multi-phase communication channel are selected, the best phase channel of link quality between the two is selected as the information transmission channel, the signal listening phase of the three-phase relay communication node in the beacon time slot area is the information transmission channel, and the sending phase information of the remaining signals is adjusted; a single-phase communication node selects a three-phase relay communication node with the best communication link quality as a proxy node after entering the network; if there is a three-phase relay communication node with better communication link quality, the single-phase communication node changes the full-power proxy node after selecting a full-power proxy node; when the master node reads the meter, the nodes in the node set with a certain three-phase relay communication node as the full-power proxy node can be read point by point or the business data of the three-phase relay communication node can be directly read.

Description

Technical Field

[0001] This invention belongs to the field of broadband carrier communication technology, and particularly relates to a communication method for a broadband carrier communication network. Background Technology

[0002] Compared to narrowband carrier communication technology, broadband carrier communication technology employs modulation techniques such as spread spectrum and OFDM (Orthogonal Frequency Division Multiplexing), which improves bandwidth utilization, eliminates interference between channels, reduces passive signal absorption and sudden interference, and achieves high-speed and reliable data communication. It also overcomes problems such as significant line noise and signal attenuation in power line communication. With the State Grid Corporation of China and China Southern Power Grid successively releasing broadband carrier communication standards for their power grid electricity consumption information collection systems, related communication equipment has been rapidly and widely used in power grid areas across the country after the standards were promulgated, effectively improving the data communication performance of the electricity consumption information collection systems.

[0003] Although broadband carrier communication technology possesses strong communication capabilities at the physical layer, its link layer protocol has some shortcomings. For example, according to existing communication protocols, apart from the concentrator node which has three-phase communication capabilities, other nodes in the carrier network, whether three-phase meters or single-phase meters, only have single-phase communication capabilities. This results in low utilization efficiency of the physical layer broadband across the entire network. Furthermore, with the rapid increase in the number of devices using broadband carrier communication technology in the distribution network, the probability of mutual interference as these devices transmit carrier signals on the same power lines also increases rapidly. Therefore, the overall communication performance of current broadband carrier communication networks still has room for improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a communication method for a broadband carrier communication network that can improve network communication performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A communication method for a broadband carrier communication network, wherein the nodes in the broadband carrier communication network include master nodes and slave nodes. The master node is a broadband carrier communication module built into a concentrator. The slave nodes include broadband carrier communication modules built into electricity meters or smart switches and meter box relay broadband carrier communication modules set at the line entrance of each meter box. The broadband carrier communication modules built into electricity meters or smart switches are single-phase communication nodes, and the meter box relay broadband carrier communication modules set at the line entrance of each meter box are three-phase relay communication nodes. The three-phase relay communication nodes and the master node have three-phase communication capabilities, and the single-phase communication nodes have unidirectional communication capabilities. The master node uses a beacon period-based superframe time slot structure for network communication. One beacon period includes a beacon time slot area, a TDMA time slot area, and a CSMA time slot area.

[0007] S1. After the nodes in the broadband carrier communication network are powered on, the network begins to form. The master node sends a central beacon signal, and the single-phase communication nodes and the three-phase relay communication nodes join the network. The joining steps of the three-phase relay communication nodes are as follows:

[0008] S1-1. Listen to the signals sent by neighboring nodes in turn on the three phase lines A / B / C;

[0009] S1-2. Select a proxy node from the neighboring nodes that can listen to the signal and join the network;

[0010] S2. For any two nodes with three-phase communication capability that have multi-phase communication channels, select the phase channel with the best link quality between them as the information transmission channel. The signal monitoring phase of the three-phase relay communication node in the beacon time slot area is the information transmission channel. When the three-phase relay communication node correctly receives a beacon signal on the information transmission channel, it adjusts the phase according to the transmission phase information of the remaining beacon signals.

[0011] S3. After the single-phase communication node enters the network, it selects a three-phase relay communication node with the best communication link quality as its proxy node.

[0012] S4. During network operation, for a single-phase communication node M, if the bidirectional link signal reception signal-to-noise ratio between the single-phase communication node M and a three-phase relay communication node N is better than the bidirectional link signal reception signal-to-noise ratio between the single-phase communication node M and other three-phase relay communication nodes, and the bidirectional link signal reception signal-to-noise ratio between the two is greater than a preset threshold, the three-phase relay communication node N sends a full proxy change request message to the master node, and the master node replies to the three-phase relay communication node N with a full proxy confirmation message after receiving it.

[0013] S5. If a node that has already selected a full proxy node listens to a three-phase relay communication node with a better communication link quality, it sends a full proxy change request message to the master node. After receiving the message, the master node replies with a full proxy confirmation message to the node that has already selected a full proxy node.

[0014] S6. For a certain three-phase relay communication node N, the master node performs meter readings on the nodes in the node set that uses the three-phase relay communication node N as the authorized agent node in any of the following ways:

[0015] a) Read the meters point by point from each node in the node set;

[0016] b) Copy the service data of the three-phase relay communication node N.

[0017] Furthermore, when a slave node joins the network, it sends an association request message to the master node. The content of the association request message includes at least the site MAC address, candidate proxy network short address, phase line and device type. The device type includes meter reader, concentrator local communication unit, meter communication unit, repeater, type II collector, type I collector and meter box relay broadband carrier communication module.

[0018] Furthermore, after the three-phase relay communication node joins the network, the network short address range assigned to the three-phase relay communication node by the master node is [3001, 3200].

[0019] Furthermore, after the single-phase communication node selects the full-authority proxy node and receives the full-authority proxy confirmation message from the master node, it will only maintain the route between itself and the full-authority proxy node, and will no longer periodically send discovery list messages or relay service data messages of other nodes. The master node will no longer arrange for the single-phase communication node to send discovery beacons.

[0020] Furthermore, after the three-phase relay communication node joins the network, the master node defaults to the three-phase relay communication node as a proxy beacon transmitting node, and allocates three beacon time slots to it, and transmits the proxy beacon signal once in turn in the three phases A / B / C.

[0021] Furthermore, the master node allocates TDMA time slots on demand based on the service load level of each agent node within the current beacon period.

[0022] Furthermore, for a proxy beacon transmitting node that has been allocated several TDMA time slots, the rules for using these TDMA time slots are as follows:

[0023] a) Several TDMA time slots are arranged consecutively, and the proxy beacon transmitting node can transmit signals across time slots;

[0024] b) The proxy beacon transmitting node can transmit both service data signals and non-service data signals;

[0025] c) If another node receives a signal from the proxy beacon sending node and needs to reply or respond, it immediately sends a reply or response signal;

[0026] d) Nodes allocated TDMA time slot resources shall preferentially transmit service data signals and non-service data signals without contention in the TDMA time slot area. When TDMA time slot resources are insufficient, the CSMA channel contention access mechanism shall be used to transmit signals in the CSMA time slot area. Nodes not allocated TDMA time slot resources shall use the CSMA channel contention access mechanism to transmit signals in the CSMA time slot area.

[0027] As can be seen from the above technical solutions, the method of the present invention utilizes the circuit characteristics of electricity meters being centrally installed in meter boxes. A meter box relay broadband carrier communication module with three-phase communication capability is installed at the line entrance of each meter box. This meter box relay broadband carrier communication module, acting as a three-phase relay communication node, does not generate its own service message data and can perform network topology maintenance. Correspondingly, the single-phase communication nodes within the meter box no longer need to perform network topology maintenance, effectively improving the network topology, significantly reducing the number of non-service data messages sent in the network, achieving a more orderly channel access process, reducing the probability of signal collisions, and increasing the throughput of the broadband carrier communication network, thereby effectively improving the overall network communication performance. Attached Figure Description

[0028] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of the power supply line for a three-phase four-wire distribution area;

[0030] Figure 2 A schematic diagram of the working phase of a node in a broadband carrier communication network in a three-phase four-wire distribution network;

[0031] Figure 3 This is the installation wiring diagram for the three-phase relay communication module in the meter box;

[0032] Figure 4 This is a schematic diagram of a superframe structure in a broadband carrier network.

[0033] Figure 5 A schematic diagram illustrating the content definition of non-central beacon information;

[0034] Figure 6 This is a flowchart of the method of the present invention;

[0035] Figure 7 This is a schematic diagram of a tree network topology for a broadband carrier communication network.

[0036] Figure 8 A schematic diagram illustrating the coexistence of multi-phase communication links between nodes with three-phase communication capabilities;

[0037] Figure 9 This is a schematic diagram of time slot allocation for the TDMA time slot region;

[0038] Figure 10 A diagram illustrating the usage rules for allocating TDMA time slot resources to proxy nodes. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings. In the detailed description of the embodiments of the present invention, for ease of explanation, the drawings illustrating the device structure will be partially enlarged without adhering to the general scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of the present invention. It should be noted that the drawings are in a simplified form and use non-precise scales, solely for the purpose of conveniently and clearly illustrating the embodiments of the present invention. Additionally, in the description of this application, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Terms such as "positive," "negative," "bottom," "upper," and "lower" indicate orientation or positional relationships based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] In low-voltage distribution networks, transmission lines are based on transformer substations and use a three-phase four-wire system, such as... Figure 1 As shown, the three lines represent phases A, B, and C, respectively, and the other line is the neutral line N. In a three-phase power supply, these three currents are used as live wires, connected to different electrical loads, and then connected to a common neutral wire. In a three-phase system, when the three phases are balanced, there is no current in the neutral wire (zero line).

[0042] In terms of equipment form, the broadband carrier communication network of the electricity information collection system has broadband carrier communication modules embedded in three-phase / single-phase smart meters or smart switches. Because the power supply lines in the distribution substation are long and have many branching lines, and the transmission distance of the broadband carrier communication signal is limited, a multi-hop network is formed with the broadband carrier communication module in the concentrator as the network master node and other broadband carrier communication modules as network slave nodes.

[0043] The current broadband carrier communication standard specifies the following hardware requirements for nodes in a broadband carrier communication network: Figure 2 ):

[0044] 1) The broadband carrier communication module embedded in the concentrator is the network master node (CCO), which has three-phase communication capability. The network master node has a single half-duplex physical communication channel and can send or receive signals on the three phase lines A / B / C in turn according to the signaling instructions.

[0045] 2) The remaining broadband carrier communication modules are network slave nodes. Network slave nodes can only send and receive signals on a fixed phase.

[0046] According to the current broadband carrier communication standard, apart from the CCO, all other nodes in the network, whether three-phase communication modules in a three-phase meter or single-phase communication modules in a single-phase meter, are single physical communication channels. This means that the transceivers of broadband carrier communication modules other than the CCO can only transmit or receive signals on one of the three phase lines (A, B, and C) at any given time. In contrast, the CCO can autonomously change its operating phase line by switching, and can transmit or receive signals on all three phase lines in turn.

[0047] To save installation space and provide physical protection for electricity meters, meters are often installed in meter boxes as the basic unit. Meters within a local power supply area are typically housed in a multi-position meter box. Therefore, broadband carrier communication networks based on existing broadband carrier communication standards face the following problems during network operation:

[0048] 1. The standard stipulates that the number of nodes allowed to access a broadband carrier subnet is limited, with an upper limit of about 1,000. This results in a limited number of communication nodes that can be accommodated on a single distribution subnet line. However, the number of devices with broadband carrier communication modules installed in distribution subnets is increasing. Whether it is a large-scale network in a single subnet or a parallel network of multiple different small and medium-sized regular subnets, these nodes transmit signals on the same channel (three-phase power supply line). Although the standard has formulated relevant multi-subnet coordination communication mechanisms and CSMA channel random contention access strategies, each node needs to transmit service data signals and network management signals randomly or periodically. Once there are too many communication nodes on the distribution subnet line, the probability of signal collision will increase rapidly, and the network throughput performance will be severely degraded.

[0049] 2. As the requirements for distribution network management level continue to increase, customers expect to obtain richer and more real-time network operation monitoring data, and the frequency of data acquisition is also increasing. Existing standard channel access protocols perform well in scenarios with light network load, but once the network load level increases, the network throughput performance drops significantly, thus limiting their ability to support high-frequency data acquisition.

[0050] To address the above problems, this invention utilizes the circuit characteristics of electricity meters being centrally installed within meter boxes to propose a communication method for a broadband carrier communication network. The broadband carrier communication network includes a master node and slave nodes. The master node is a broadband carrier communication module built into a concentrator, and the slave nodes include broadband carrier communication modules built into electricity meters or smart switches, as well as meter box relay broadband carrier communication modules located at the line entrance of each meter box. Both the broadband carrier communication modules built into the concentrator and the meter box relay broadband carrier communication modules located at the line entrance of each meter box have three-phase communication capabilities, allowing them to autonomously change the operating phase lines and alternately transmit or receive signals on phase lines A, B, and C. The broadband carrier communication modules built into the electricity meters or smart switches only have single-phase communication capabilities, allowing them to transmit or receive signals only on one of the three phase lines (A, B, and C). For ease of description, the broadband carrier communication module with three-phase alternating communication capability installed at the line entrance of each meter box is defined as a three-phase relay communication node, the broadband carrier communication module with only single-phase communication capability built into the meter or smart switch is defined as a single-phase communication node, and the broadband carrier communication module built into the concentrator is called CCO.

[0051] like Figure 3 As shown, the meter box relay broadband carrier communication module is installed at the line entrance of each meter box. The meter box relay broadband carrier communication module has the same physical layer communication capability as the network master node. It can take turns sending and receiving signals on the three-phase line through switching. Moreover, the meter box relay broadband carrier communication module does not generate its own service message data and is a relay communication node.

[0052] The Central Control Node (CCO), acting as the central control node (master node) for network operation, uses a beacon-period-based superframe time slot structure for network communication, while simultaneously using beacon signals to maintain the synchronization and orderly operation of the entire network. In the State Grid's "Technical Specification for Interoperability of High-Speed ​​Carrier Communication on Low-Voltage Power Lines," the time slot division for superframes is as follows: Figure 4 As shown, a beacon period includes four time slots: beacon time slot area, TDMA time slot area, CSMA time slot area, and bound CSMA time slot area. China Southern Power Grid's "Technical Requirements for Broadband Carrier Communication in Centralized Meter Reading Systems for Low-Voltage Power Users" also uses a similar structure for superframe time slot division, only the order of the four time slots is different: beacon time slot area, CSMA time slot area, TDMA time slot area, and bound CSMA time slot area. Of the four time slots in a beacon period, the TDMA time slot area and the bound CSMA time slot area are generally only used during remote network upgrades. Therefore, during normal network communication, the beacon period generally only includes the beacon time slot area and the CSMA time slot area, meaning the length of the other two time slot areas is set to 0. Figure 4The superframe structure does not show the bound CSMA time slot region.

[0053] The Central Controller (CCO) manages the synchronized and orderly structure of the entire network time slots using beacon signals. There are three types of beacon signals: central beacon, proxy beacon, and discovery beacon. At the start of each beacon cycle, the CCO begins transmitting the central beacon signal. Its signaling content carries the time slot parameters for that beacon cycle and other network management information. The time slot parameters mainly include the duration of the beacon time slot, the number of the three types of beacon time slots (the values ​​of X, Y, and Z), X central beacon time slots (transmitted by the CCO node), Y proxy beacon time slots, and Z discovery beacon time slots, as well as the network short addresses (TEIs) of the Y+Z transmitting nodes corresponding to the non-central beacon time slots, and related parameters for CSMA time slot areas and bound CSMA time slot areas.

[0054] When a node in the network receives a beacon signal from another node, if it discovers through signaling content parsing that it is one of the aforementioned Y+Z sending nodes, and its assigned beacon time slot has not yet arrived on the timeline, it will relay a proxy beacon signal or a discovery beacon signal in its own time slot after the beacon time slot arrives. Based on this mechanism and the selection of appropriate proxy relay nodes, the CCO can utilize these X+Y+Z beacon time slots to achieve downlink network-wide broadcast transmission of its beacon signaling information within a beacon cycle.

[0055] According to the current State Grid broadband carrier communication standard, when a network slave node joins the network, it needs to send an association request message to the CCO (Center for Control and Control). As shown in Table 1, the content of the association request message includes at least the site MAC address, candidate proxy network short address, phase line, and device type. The device types in the association request message of this invention include meter readers, concentrator local communication units, meter communication units, repeaters, Type II collectors, Type I collectors, and meter box relay broadband carrier communication modules, as shown in Table 2. The meter box relay broadband carrier communication module is a new definition added to the association request message in this invention. When sending the association request message, the meter box relay broadband carrier communication module can indicate its device type to the CCO through the newly added device type definition.

[0056] Table 1. Field Definitions for Related Request Messages

[0057]

[0058] New definition of the device type field in Table 2

[0059]

[0060]

[0061] In a single signal transmission, the physical layer of a broadband carrier uses the same signal structure for all types of beacon signals, including the central beacon, proxy beacon, and discovery beacon. These beacon signals all include a preamble, a frame control signal, and a payload signal. The preamble is used for signal acquisition and synchronization; the frame control signal uses a predefined modulation and coding scheme and a fixed 16-byte physical block. In addition to basic information such as network name and network time information, the frame control signal further indicates the physical layer format of the subsequent payload signal, thus helping the receiver to correctly receive and parse the payload signal. The payload signal includes beacon management messages (carrying network time slot parameters and other network management information), payload field check sequences (for verifying payload fields), physical block check sequences (for verifying physical blocks), and other signaling content. The beacon management information field defines the time slot allocation for the superframe.

[0062] Table 3 defines the content of the time slot allocation message field in the State Grid standard (the design concept of the time slot allocation information in the Southern Power Grid standard is basically the same as that of the State Grid, and the State Grid standard is used as an example for explanation here).

[0063] Table 3. Content Definitions of Time Slot Allocation Message Fields

[0064]

[0065]

[0066] The length of the non-central beacon information in the time slot allocation message field is a dynamic value. It carries information indicating the allocation of Y+Z non-central beacon time slots, including the short address of the allocating node and the beacon type for that time slot. Figure 5 As shown.

[0067] Since the present invention installs a meter box relay broadband carrier communication module at the line entrance of each meter box, certain fields in the time slot allocation message are modified. Therefore, compared with Table 3, the modified parts of the time slot allocation message field definitions are shown in Table 4. The modified fields are TDMA time slot length, TDMA time slot link identifier, and non-central beacon information. The contents of other fields not listed in Table 4 are not modified and are the same as the original standard, consistent with Table 3.

[0068] Table 4 New Definitions of Time Slot Allocation Message Fields

[0069]

[0070]

[0071] To fully utilize the advantages of three-phase relay communication nodes, this invention also modifies the content of the management message type in the beacon management message, adding a new message type—the full agency change request message, whose message type identifier is 0x000D. The content of the new message is the same as that of the agency change request message, and the only difference is the message type identifier.

[0072] Based on the above hardware and protocol improvements, including the addition of a broadband carrier communication module for the relay at the line entrance of each meter box, and modifications to certain content in the association request message and beacon signal, such as... Figure 6 As shown, the steps of the method of the present invention are as follows:

[0073] S1. After the node is powered on, network formation begins. The CCO (Network Master Node) runs each beacon cycle sequentially. The CCO sends the central beacon signal in its own time slot. Non-CCO nodes (network slave nodes) in the network include single-phase communication nodes built into the meter and three-phase relay communication nodes set at the line entrance of each meter box. Single-phase communication nodes use the original network access mechanism, which is described in the broadband carrier communication standards of State Grid and China Southern Power Grid. This invention does not improve the network access process of single-phase communication nodes, so it will not be described in detail here. The network access steps of the three-phase relay communication nodes in this invention are as follows:

[0074] S1-1. The three-phase relay communication node takes turns listening to the signals sent by the neighboring node on the three phase lines A / B / C. The listening time of each phase is consistent with the listening time when the single-phase communication node enters the network.

[0075] S1-2. After completing the listening process, the three-phase relay communication node selects a proxy node (parent node) from among its neighboring nodes that can listen to the signal and joins the network. The strategy for selecting a proxy node for the three-phase relay communication node is the same as that for the single-phase communication node. After selecting the proxy node using the same strategy as the single-phase communication node, the three-phase relay communication node uses the same network entry mechanism as the single-phase communication node to complete the subsequent network entry process. The strategy for selecting a proxy node for the single-phase communication node is described in the broadband carrier communication standards of State Grid and China Southern Power Grid. This invention does not improve the process of selecting a proxy node for the single-phase communication node, and will not be elaborated here. After the network node joins the network, a routing layer will be formed as follows: Figure 7 The diagram shows a multi-level hierarchical tree network centered on the CCO, with the Agent Coordinator (PCO) acting as the relay agent, connecting all slave sites (STAs).

[0076] After a network node joins the network, the CCO assigns it a 12-bit network short address (TEI) to uniquely identify it within the network (the CCO's short address is 0 by default, and the network-wide broadcast address is fixed at 4095). The value range of the network short address is 0 to 4095. However, according to the broadband carrier communication standard, the maximum number of network nodes is only 1015 (State Grid) or 1024 (Southern Grid), utilizing only about 1 / 4 of the address space, leaving approximately 3,000 free addresses. To distinguish between single-phase communication nodes and three-phase relay communication nodes in the network, this invention optionally limits the range of network short addresses assigned by the CCO to three-phase relay communication nodes to [3001, 3200]. The remaining available short addresses can be assigned to other types of nodes. Thus, after the network is operational, nodes can identify the device type of a communication node through the value of its network short address (the typical number of meter boxes in a distribution area is several or dozens, and in most cases, it will not exceed 100).

[0077] S2. For any two nodes with three-phase communication capability (the nodes with three-phase communication capability are CCO and three-phase relay communication nodes) that have multi-phase communication channels, select the phase channel with the best link quality from the multiple communication channels between the two nodes with three-phase communication capability as the information transmission channel between the two nodes, and use the signal reception of the phase channel with the best link quality to evaluate the communication link quality between the two nodes. In the beacon time slot area, the signal listening phase of the three-phase relay communication node is first set to the phase channel with the best link quality between itself and its own agent node, that is, the signal listening phase of the three-phase relay communication node is set to the information transmission channel between the two nodes. When a beacon signal is correctly received on the information transmission channel, the transmission phase is adjusted according to the transmission phase information of the remaining beacon signals.

[0078] In traditional applications of broadband carrier communication networks, only the CCO (Content Controller Object) has three-phase communication capability, while other nodes only have single-phase communication capability. Therefore, the communication channel between any two nodes in the network is actually a single-phase channel. However, in this invention, in addition to the CCO having three-phase communication capability, the three-phase relay communication node located at the line entrance of each meter box also has three-phase communication capability. As the number of nodes with three-phase communication capability increases in the network, communication between two nodes with three-phase communication capability may experience issues such as… Figure 8 The problem of coexistence of multi-phase communication channels is illustrated.

[0079] The CCO (Center of Origin) is the source of the beacon signal. The beacon signal carries the address information of all relay nodes. Upon receiving the beacon signal, these relay nodes relay it within a specified time period according to its content. When a relay node receives a beacon signal, the subsequent beacon signals are the remaining beacon signals. The relay node in this invention is a three-phase node with three-phase communication capability. Transmit and receive channels exist on all three phases of the line. A three-phase node can only transmit / receive signals on one phase at a time. If it wants to listen to another three-phase neighbor node... The signal should be monitored on the phase channel with the best link quality. When a three-phase node relays a beacon signal, it will take turns transmitting the beacon signal on each of the three phases. Therefore, the three-phase relay communication node of this invention will definitely receive the beacon signal by first monitoring on the phase channel with the best link quality. The beacon signal will carry the address of the relay node (the order of the address implies the signal relay transmission time). Since a node knows the phase information of its neighboring nodes, it can adjust the phase accordingly based on the transmission phase information of the remaining beacon signals to achieve correct full network coverage of the beacon signal.

[0080] S3. After a single-phase communication node (a broadband carrier communication module embedded in the meter) is connected to the network, it selects a three-phase relay communication node with the best communication link quality as its proxy node. In actual applications, the line distance between the three-phase relay communication node installed at the line entrance of the meter box and the broadband carrier communication module installed in the meter box is less than one meter. Therefore, the communication link quality between each single-phase communication node and the three-phase relay communication node at the line entrance of its own meter box is actually optimal. Therefore, theoretically, each single-phase communication node will select the three-phase relay communication node at the line entrance of its own meter box as its proxy node.

[0081] S4. During network operation, for a single-phase communication node M, if there exists a three-phase relay communication node N, and the bidirectional link signal reception signal-to-noise ratio between the three-phase relay communication node N and the single-phase communication node M is better than the bidirectional link signal reception signal-to-noise ratio between the single-phase communication node N and other three-phase relay communication nodes, and the bidirectional link signal reception signal-to-noise ratio between the two (M and N) is greater than a preset threshold R (the typical value of R is 20dB), then it is considered that the three-phase relay communication node N is installed at the line entrance of the meter box where the single-phase communication node M is located. The three-phase relay communication node N will send a full agency change request message to the CCO. After receiving it, the CCO will reply with a full agency confirmation message to the three-phase relay communication node N.

[0082] According to the routing protocol, both the uplink full proxy change request message and the downlink full proxy confirmation message require relay forwarding by node N. Therefore, node N knows that node M regards it as a full proxy node. Each slave node must select a node as its proxy node when joining the network and during network operation. During the network entry process, the node will carry the short address of its selected proxy node in the association request message. If the slave node needs to change its proxy node during network operation, it must send a proxy change request message to the CCO. After receiving the message, the CCO will reply with a proxy change confirmation message.

[0083] S5. During network operation, if a node that has selected a full proxy node listens to a three-phase relay communication node with a better communication link quality, it sends a full proxy change request message to the CCO, requesting a replacement of the full proxy node. Upon receiving the request, the CCO will reply to the node with a full proxy confirmation message. If the receiving link quality between a node that has selected a full proxy node and its full proxy node is lower than a preset threshold R, and no new full proxy node that meets the requirements can be found, the node sends a proxy change request message to the CCO, and the current full proxy node relationship is canceled by default.

[0084] After a single-phase communication node completes the selection of a full-authority agent node and receives a full-authority agent confirmation message from the CCO, it will only maintain the route between itself and the full-authority agent node, and will no longer perform network topology maintenance work, including no longer periodically sending discovery list messages, nor relaying service data messages of other nodes, and the CCO will no longer arrange for single-phase communication nodes to send discovery beacons; since the three-phase relay communication node is installed at the line entrance of the meter box, although all single-phase communication nodes in the meter box no longer perform network topology maintenance work, the three-phase relay communication node still performs network topology maintenance work, so it will not affect the link connectivity of the entire network topology;

[0085] S6. For a certain three-phase relay communication node N, assuming it is the authorized agent node of a certain node set O, the CCO performs meter readings on the nodes in set O using any of the following methods:

[0086] a) Use the existing meter reading method to read the nodes in set O point by point;

[0087] b) Reading the service data of node N: Since the three-phase relay communication node N itself does not have service data, after the three-phase relay communication node N receives the message to read its own service data, the default is that CCO should read all nodes in set O in batch.

[0088] After step S1, once the three-phase relay communication node joins the network, the CCO will default to it as a proxy beacon transmitting node and allocate three beacon time slots to it, that is, to transmit the proxy beacon signal once in turn in the three phases A / B / C.

[0089] The CCO allocates TDMA time slots on demand based on the service load levels of each agent node within the current beacon period. For example... Figure 9 As shown, the K+1 nodes transmitting beacon signals are Z0, Z1, Z2, ..., Z... K (Z0 is the CCO node, Z1, Z2, ..., Z) K (These are three-phase relay communication nodes acting as proxy beacon transmitting nodes). The number of TDMA time slots allocated to these nodes, in node order, are N0, N1, N2, ..., N. K ,but Figure 5 The total length of the TDMA time slot region is N0+N1+N2+,…,+N K One TDMA time slot.

[0090] For a certain proxy beacon sending node Z k (k = 1, 2, ..., K), assuming the proxy beacon sending node is assigned to N k If there are multiple TDMA time slots, these TDMA time slots will be used according to the following rules:

[0091] a)N k The TDMA time slots are arranged consecutively, that is, these time slots are connected into one block, and the proxy beacon transmitting node Z... k Signals can be transmitted across time slots;

[0092] b) Agent beacon sending node Z k It can send both business data signals and non-business data signals;

[0093] c) If another node receives the proxy beacon sent by node Z k If a signal is received that requires a reply or response, send a reply or response signal immediately.

[0094] d) Nodes allocated TDMA time slot resources prioritize contention-free transmission of service data signals and non-service data signals in the TDMA time slot area. When TDMA time slot resources are insufficient, they perform contention-based random transmission in subsequent CSMA time slot areas. Nodes not allocated TDMA time slot resources perform contention-based random transmission in the CSMA time slot area. Contention-based random transmission in the CSMA time slot area refers to using the conventional CSMA channel contention access mechanism to transmit signals. The CSMA channel contention access mechanism is a mature and conventional technology and is not an innovation of this invention, so it will not be elaborated here.

[0095] According to existing standards, each node entering the network needs to periodically and frequently send discovery list messages and discovery beacon signals. These signals consume a significant amount of channel bandwidth resources. Moreover, when the network node scale is large, collisions are likely to occur between discovery list messages sent by nodes using the CSMA channel contention access mechanism in the CSMA time slot area. This not only increases the link quality assessment error between nodes but also degrades the reception success rate performance of other types of signals sent in the same CSMA time slot area. The method of this invention sets up a three-phase relay communication node at the line entrance of each meter box. Without affecting the network topology connectivity, each meter box only needs one three-phase relay communication node to continue to perform network topology and route maintenance functions. All meters in the meter box no longer need to send discovery list messages and discovery beacon signals, and the amount of non-service data signals sent in the line is greatly reduced, effectively reducing network routing channel overhead.

[0096] Furthermore, according to existing standards, the CCO and other agent nodes can only be allocated TDMA time slot resources of the same length, and these time slots can only support the transmission of the same type of service, which is basically of no application value. In the method of this invention, the CCO can allocate different numbers of TDMA time slot resources to itself and other agent nodes as needed, and remove the restriction on service type. Each node can flexibly use these time slot resources according to its current service situation. Under this mechanism, the collision-free nature of signals transmitted on TDMA time slots can be guaranteed, while the network service load level in the CSMA time slot area can be significantly reduced, thereby reducing the collision probability of signals transmitted in the time slot area.

[0097] To verify the performance of the method of this invention, with the support of Zhuhai Power Grid Company, a large residential substation in Zhuhai City was selected for performance testing. The substation contained 654 meters and 62 meter boxes. Due to the large number of meters and the large scale of the network nodes in this substation, the average meter reading success rate was low, and the transmission delay of the meter reading data was significant.

[0098] The researchers installed a meter box relay broadband carrier communication module in each meter box of the experimental area, and upgraded the software for all network nodes. Then, they conducted a network-wide meter reading performance test with frozen meter data every 15 minutes. The meter reading success rate and average reading latency data for 10 consecutive 15-minute frozen meter readings before and after the upgrade are shown in the table below:

[0099] Table 5. Meter reading performance of the experimental area before and after the upgrade.

[0100]

[0101] The test results show that due to the large number of meter nodes in this distribution area, the network service load is high when executing the existing standard protocol. Meter reading data signals are prone to collisions during transmission in the CSMA time slot, leading to reception failures, multiple retransmissions, or even transmission failures. However, after installing a certain number of three-phase communication modules for the meter boxes in the experimental distribution area, the load of non-service data packets in the network channel was significantly reduced. Combined with the on-demand allocation of TDMA time slots, the probability of collisions in meter reading data signals was greatly reduced, and the single-hop transmission success rate was significantly improved, thus ensuring a high success rate and low latency for meter reading across the entire network.

[0102] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A communication method for a broadband carrier communication network, characterized in that: The nodes in the broadband carrier communication network include master nodes and slave nodes. The master node is a broadband carrier communication module built into the concentrator. The slave nodes include broadband carrier communication modules built into the electricity meter or smart switch and meter box relay broadband carrier communication modules set at the line entrance of each meter box. The broadband carrier communication modules built into the electricity meter or smart switch are single-phase communication nodes, and the meter box relay broadband carrier communication modules set at the line entrance of each meter box are three-phase relay communication nodes. The three-phase relay communication nodes and the master node have three-phase communication capabilities, and the single-phase communication nodes have single-phase communication capabilities. The master node uses a beacon period-based superframe time slot structure for network communication. One beacon period includes a beacon time slot area, a TDMA time slot area, and a CSMA time slot area. S1. After the nodes in the broadband carrier communication network are powered on, the network begins to form. The master node sends a central beacon signal, and the single-phase communication nodes and the three-phase relay communication nodes join the network. The joining steps of the three-phase relay communication nodes are as follows: S1-1. Listen to the signals sent by neighboring nodes in turn on the three phase lines A / B / C; S1-2. Select a proxy node from the neighboring nodes that can listen to the signal and join the network; S2. For any two nodes with three-phase communication capability that have multi-phase communication channels, select the phase channel with the best link quality between them as the information transmission channel. The signal monitoring phase of the three-phase relay communication node in the beacon time slot area is the information transmission channel. When the three-phase relay communication node correctly receives a beacon signal on the information transmission channel, it adjusts the phase according to the transmission phase information of the remaining beacon signals. S3. After the single-phase communication node enters the network, it selects a three-phase relay communication node with the best communication link quality as its proxy node. S4. During network operation, for a single-phase communication node M, if the bidirectional link signal reception signal-to-noise ratio between the single-phase communication node M and a three-phase relay communication node N is better than the bidirectional link signal reception signal-to-noise ratio between the single-phase communication node M and other three-phase relay communication nodes, and the bidirectional link signal reception signal-to-noise ratio between the two is greater than a preset threshold, the three-phase relay communication node N sends a full proxy change request message to the master node, and the master node replies to the three-phase relay communication node N with a full proxy confirmation message after receiving it. S5. If a node that has already selected a full proxy node listens to a three-phase relay communication node with a better communication link quality, it sends a full proxy change request message to the master node. After receiving the message, the master node replies with a full proxy confirmation message to the node that has already selected a full proxy node. S6. For a certain three-phase relay communication node N, the master node performs meter readings on the nodes in the node set that uses the three-phase relay communication node N as the authorized agent node in any of the following ways: a) Read the meters point by point from each node in the node set; b) Copy the service data of the three-phase relay communication node N.

2. The communication method of the broadband carrier communication network as described in claim 1, characterized in that: When a slave node joins the network, it sends an association request message to the master node. The content of the association request message includes at least the site MAC address, candidate proxy network short address, phase line and device type. The device type includes meter reader, concentrator local communication unit, meter communication unit, repeater, type II collector, type I collector and meter box relay broadband carrier communication module.

3. The communication method of the broadband carrier communication network as described in claim 1, characterized in that: After the three-phase relay communication node joins the network, the network short address range assigned to the three-phase relay communication node by the master node is [3001, 3200].

4. The communication method of the broadband carrier communication network as described in claim 1, characterized in that: After the single-phase communication node selects the full-authority proxy node and receives the full-authority proxy confirmation message from the master node, it will only maintain the route between itself and the full-authority proxy node, and will no longer periodically send discovery list messages or relay service data messages of other nodes. The master node will no longer arrange for the single-phase communication node to send discovery beacons.

5. The communication method of the broadband carrier communication network as described in claim 1, characterized in that: After the three-phase relay communication node joins the network, the master node defaults to the three-phase relay communication node as a proxy beacon transmitting node, and allocates three beacon time slots to it, and transmits the proxy beacon signal once in turn in the three phases A / B / C.

6. The communication method of the broadband carrier communication network as described in claim 1, characterized in that: The master node allocates TDMA time slots on demand based on the service load level of each agent node within the current beacon period.

7. The communication method of the broadband carrier communication network as described in claim 6, characterized in that: For a proxy beacon transmitting node that has been allocated several TDMA time slots, the rules for using these TDMA time slots are as follows: a) Several TDMA time slots are arranged consecutively, and the proxy beacon transmitting node can transmit signals across time slots; b) The proxy beacon transmitting node can transmit both service data signals and non-service data signals; c) If another node receives a signal from the proxy beacon sending node and needs to reply or respond, it immediately sends a reply or response signal; d) Nodes allocated TDMA time slot resources shall preferentially transmit service data signals and non-service data signals without contention in the TDMA time slot area. When TDMA time slot resources are insufficient, the CSMA channel contention access mechanism shall be used to transmit signals in the CSMA time slot area. Nodes not allocated TDMA time slot resources shall use the CSMA channel contention access mechanism to transmit signals in the CSMA time slot area.

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