CN1388653A - Bandspread communication network system in low-voltage distribution network and its communication method - Google Patents

Abstract

The low-voltage power distribution network spread-spectrum communication network system and its communication method belong to the field of low-voltage power line communication technology. "Master-slave communication system; its communication method is characterized in that: on the basis of the proposed network nodes and network segments, the routing table in the concentrator and the router is established, the low address of the network node - the phase comparison table, and the centralized Router <=>; network segment router <=>; low address of network node <=>; one-to-one correspondence between the phases of two-way communication. ID (identification) <=>; network node address table, which establishes a unique correspondence between the user ID information sent by the computer and the destination address, and provides a technical basis for meter reading of physical quantities such as user electricity consumption that need to be telemetered by the network. It has the advantages of stable and reliable communication, large communication range, less affected by noise interference and convenient use.

Description

Low-voltage distribution network spread-spectrum communication network system and its communication method

technical field

A low-voltage distribution network spread-spectrum communication network system and a communication method thereof belong to the technical field of low-voltage power line communication.

Background technique

The use of power lines as the signal transmission medium to realize communication is a technology that research and industrial departments such as electric power, communication, and network in various countries have been devoting to research and development. Power line communication is usually divided according to the voltage level of the power network, which can be divided into high voltage power line communication (above 100KV), medium voltage power line communication (1KV~100KV) and low voltage power line communication (below 1kV, 380V/220V). As far as the characteristics of the power line communication channel are concerned, the high-voltage power line communication environment is the best, followed by the medium-voltage power line environment, and the worst is the low-voltage power line communication environment. Low-voltage power line communication is also called low-voltage distribution network communication. Divided from the perspective of applied communication technology, power line communication technology is divided into narrowband modulation technology and broadband (spread spectrum) modulation technology.

In terms of research and development of low-voltage distribution network communication technology, research institutions in the United Kingdom, Germany, the United States, Japan, Belgium, Israel and other countries have conducted research on this technology from different angles.

There are two main types of power line communication technologies for low-voltage distribution networks in the world: European standard and non-European standard.

European standard category: generally refers to the distribution network communication technology that adopts the European CENELEC standard EN50065-1 (working frequency range is 3-148.5kHz, maximum power 25W). Since the frequency range is relatively narrow (the maximum bandwidth is 145.5kHz), it is suitable for data transmission using narrowband modulation techniques (such as ASK, FSK, PSK). In addition to the bandwidth, the transmission rate is also related to the noise of the distribution network in this frequency range. According to the research results published internationally and the industrial test results of the actual distribution network in China by the Department of Electrical Engineering of Tsinghua University, the noise level of the distribution network in this frequency band is -40~-80dBmW/Hz, which is relatively high. So only a lower transfer rate (generally 2.4kbit/s or lower) can be achieved. If spread spectrum technology is used in this frequency band, because the bandwidth is small, the processing gain obtained by spread spectrum is about 18, and the effect of spread spectrum superiority is not obvious.

Non-European standard category: generally refers to the distribution network communication technology that adopts the non-European CENELEC standard EN50065-1. Typical non-European standards include the American FCC standard (100~450kHz, maximum power 25W). The industrial test results of the Department of Electrical Engineering of Tsinghua University in China's actual distribution network show that the noise of the distribution network in this frequency range is white noise, and the noise level is -90dBmW/Hz, which is far lower than the noise level of the European standard frequency band. The bandwidth of the FCC frequency band is more than twice that of CENELEC, so a higher transmission rate (generally above 9.6kbit/s) and greater spread spectrum processing gain (close to 44) can be achieved in the FCC frequency band.

Based on European standards or FCC standards, some companies produce modem chips (or MODEMs) that meet the standards. Such as MODEM chips ST7536 and ST7537 that meet European standards; such as MODEM chips LM1893, AN192, SSCP200 that meet FCC standards;

These commercial modem chips have the function of modulating a standard output digital signal to a continuous-time signal, or demodulating a received modulated signal to a digital signal.

The main problems faced in realizing communication on the low-voltage distribution network are (1) channel change attenuation—different access points and different time ranges are large, and have a large correlation with load switching on the network, and there are often transmission zero points; (2) Random interference and noise - Harmonic pollution and background noise from various users make the peak-peak value of interference and noise on the line up to 20V.

Studies in recent years have shown that the use of broadband power line spread spectrum communication technology can overcome the harsh communication environment of low-voltage power line communication to a certain extent, and has obvious advantages compared with narrowband communication methods or narrowband spread spectrum methods.

When using the spread spectrum communication method to carry out network communication on the low-voltage distribution network, due to the complexity of the channel of the low-voltage distribution network, the direct communication distance between any two points on the network is generally less than 500 meters. In special cases, even if the distance is relatively short, due to For reasons such as the bifurcation of the distribution network, the reliability of communication cannot be guaranteed; thus, it is necessary to plan the distribution network and place routers at key nodes. Under the control and management of the concentrator, these routers together with the user communication terminals constitute a complete distribution network spread spectrum communication network.

Contents of the invention

The purpose of the present invention is to provide a low-voltage power distribution network spread-spectrum communication network system and its communication method with stable and reliable communication, large range, convenient and flexible debugging, maintenance and use.

The low-voltage distribution network spread spectrum communication network system proposed by the present invention is characterized in that it is a "pyramid" master-slave communication system composed of computers, concentrators, routers and user terminals from top to bottom, wherein:

The computer is the apex of the system, it is not only the place where the communication information is sent, but also the end point of the user terminal feedback information;

The concentrator is a device that converts computer data packets into carrier communication packets and then transmits them to the power line. It is also a device that processes and receives carrier data packets from user terminals and feeds them back to the computer. It communicates with the computer through communication lines;

A router is used to exchange data packets between different network segments. The network segment is a collection of abstracted devices called "network nodes" that are relatively close to each other and have specified network addresses. The network address mentioned above is composed of two parts: "high address" and "status address" separated by the symbol ".", and each network node in the same network segment has the same "high address" and a The only router that can directly communicate with all network nodes in this network segment, and at least directly communicate with routers in an adjacent network segment, and through this adjacent direct communication, a router can at least find Create a communication path connecting the concentrator, so that the area covered by the entire communication system is divided into network segments directly connected by routers, which then communicate with the concentrator through the low-voltage distribution network;

The user terminal is the above-mentioned equipment that receives the carrier data of the router or the concentrator and feeds back the local data to them. It is connected to more than one user, and it communicates with the router through the low-voltage distribution network.

Both the high address and the low address are numbers between 0 and 255.

The communication method of the low-voltage distribution network spread spectrum communication network system proposed by the present invention is characterized in that: it is a top-down "pyramid" type master-slave communication mode, and it contains the following steps in turn:

(1) Initialization

(1.1) Each of the concentrator and the router stores a routing table that can be flexibly changed according to needs and has the same content and format for the same network segment. Segment, the low address in the delivery network segment and the phases represented by A, B, and C, so that when the concentrator or router obtains a data packet, it can know which delivery network should be passed by searching the routing table The router where the segment is located delivers to the router of the destination network segment, and each record in the routing table represents a possible delivery path;

(1.2) In the concentrator and the routing table, respectively store a "network segment node low-order address-phase correspondence table" with the same content and format for the same network segment, which is sequentially composed of the user node's low-order address and The phases represented by A, B, and C are respectively used to form, so that when the concentrator or router receives the node whose destination address is the network segment, it will directly send the data packet to the node according to the phase;

(2) The computer sends the information of which node the data packet is to be delivered to the concentrator in the form of the destination address together with the data packet via the communication line;

(3) After the concentrator turns the data packet into a carrier communication packet, it retrieves the routing table to know the delivery network segment of the router that the destination address will pass through and the low address of the router that needs to be delivered, so as to deliver the data packet to the delivery network segment router forwarding;

(4) The router of the delivery network segment retrieves the routing table of the network segment after receiving it, knows the delivery network segment of the router that the destination address will pass through and the low address of the router of the network segment that needs to be delivered, and sends the data packet to the next level The router of the delivery network segment forwards; after receiving the data packet, the router of the final destination network segment retrieves the "network segment node low address - phase correspondence table" of the network segment, and the router delivers the data packet to the destination according to the phase. The network node where the address resides.

In the initialization phase, in a network that strictly distinguishes users, a "user ID (Identification, ie identification)-address comparison table" should be established in the concentrator, which in turn consists of two IDs between 0 and 255 For each user, it is also a unique and long-term invariable identification number ID and the address of the network node where the user is located, so that the concentrator can know the address of the network node where the user is located through the user ID information.

Proof of use: it serves its intended purpose.

Description of drawings

Figure 1. Schematic diagram of the network structure of the low-voltage distribution network spread spectrum communication network system.

Figure 2. A typical network distribution diagram.

Figure 3. The network topology diagram after adjusting Figure 2.

Figure 4. Program flow chart for concentrator and router processing packets.

Specific implementation method

Please see Figure 1. 1 is a computer, using Lenovo Kaitian P41.5G, with an ATEN photoelectric isolation 232-485 converter; 2 is a 485 communication line; 3 is a carrier communication concentrator, 4 is a router, 5 is user terminal.

FIG. 2 is a schematic diagram of a typical network distribution, that is, division of network segments. 61~64 represent the network segment. This unified management of network node address allocation simplifies the "prior knowledge" required by routers for network node allocation. If the arrangement of addresses in the network is messy, the concentrator 3 needs to send a data packet to the address 64.18 , the concentrator 3 (the router of the 61 network segment) needs to know the specific path to reach 64.18, which will be unrealistic when there are many network nodes. Now after the unification, the concentrator 3 can deliver to the network segment 64 via the network segment 63, and then directly send the data packet to 64.18 by the router of the network segment 64; it can also forward the data packet through the router of the 62 network segment to 64 network segment routers can reach the destination address in the next step. The block diagram of the data packet processing by the concentrator and the router is shown in Figure 4, and will not be repeated here.

Tables 1 to 3 are the routing table of the concentrator and the router, the user low address--the phase table, and the user ID--address, which is an example of the comparison table of the network node address. The communication method proposed by the present invention will be described below in conjunction with an example.

At a certain moment, copy the electricity consumption of the user whose user ID is 00.14:

First, the computer sends the user ID information to the concentrator through the 485 line;

The concentrator retrieves the user ID-address comparison table, and obtains the address 64.05 of the network node where the user is located;

The concentrator learns that the data packets of network segment 64 need to be forwarded through router 63 by retrieving the routing table, and hands the user ID and destination address to phase A with the low-order address of router 63 being 2;

Router 63 retrieves the routing table after receiving it, and learns that the data packets of network segment 64 need to be forwarded through router 64, and passes the user ID and destination address to the phase of router 64 whose low-order address is 2 through phase A;

After the 64 router receives it, it first judges that it is the address of this network segment, searches the user low-order address-phase comparison table, knows that the user terminal is in phase C, and transmits the user ID information to the user terminal through phase C;

The user terminal obtains the user ID information, judges that it is a user of the network node, stores the local power consumption information of the user in a data packet whose destination address is the address of the concentrator, and returns it to the 64 router.

Router 64 retrieves the routing table after receiving it, and learns that the data packets of network segment 61 need to be forwarded by router 63, and sends the power consumption information and destination address to the phase of router 63 whose low-order address is 1 through phase B;

Router 63 retrieves the routing table after receiving it, and learns that the data packets of network segment 61 need to be handed over to concentrator 61 (that is, the "router" of network segment 61), and sends the power consumption information and destination address to the low address of concentrator 61 through phase B. is the phase of 1;

The concentrator returns the power consumption information to the computer after receiving it, and completes a copy of the user's power consumption.

Concentrator user ID—address comparison table, concentrator routing table, routing table of 63, 64 routers and user low address of 64 routers—the phase comparison table is listed as follows:

Concentrator user ID-address comparison table is as follows:

The concentrator routing table is as follows:

The routing table of router 63 is as follows:

The routing table of the 64 router is as follows:

64 router user low address - phase comparison table is as follows:

It can be seen that the communication range of the present invention is large and stable and reliable.

Claims (4)

1. low-voltage network spread-spectrum communications system contains computer and distribution line carrier equipment, it is characterized in that: it is a kind of top-down successively by computer, concentrator, and " pyramid " formula master-slave communication system that router and user terminal constitute, wherein:

Computer is the summit of system, it be the communication information place of sending be again the terminal point of terminal feedback information;

Concentrator is that the packet of computer is become the equipment that is delivered to power line behind the carrier communication bag, also is to handle and receive from the carrier data bag of user terminal and feed back to the equipment of computer, and it is communicated by letter with order wire with computer;

Router is used at different segment swapping data bag, the described network segment be a series of relative positions near and be that the equipment with network address of appointment is referred to as the set of " network node " after abstract, the described network address is by using symbol ". " to separate " high address " each other and " status address " is dimerous, and each network node in the same network segment has same " high address " and a unique router is arranged, this router except can with all-network node direct communication in this network segment, also at least can with the router direct communication of an adjacent network segment, and by this adjacent direct communication, a router can be found out the avenues of communication of a connection concentrator at least, make the area dividing of the contained lid of whole communication system become the network segment that directly is communicated with by router one by one, it is communicated by letter with concentrator through low-voltage network again;

User terminal is the carrier data of receiving router or concentrator and feeds back the said equipment of local data to them, and it is connecting more than one user, and it is through low-voltage network and router communication.

2. low-voltage network spread-spectrum communications according to claim 1 system, it is characterized in that: described high address and low order address all are numerals between 0 to 255.

3. low-voltage network spread-spectrum communications system according to claim 1 and the communication means that designs is characterized in that: the master-slave mode communication mode of its " pyramid " formula that is top-down, and it contains the following step successively:

(1) initialization

(1.1) concentrator with respectively deposit one in the router in and can change flexibly as required and the content routing table all identical for the same network segment with form, it is successively respectively by the destination network segment of representing with the high address, deliver the network segment, deliver the A that uses at interior low order address of the network segment and place thereof, B, the place phase place that C represents constitutes, when obtaining a packet with convenient concentrator or router, by the retrieval routing table, recognize which deliver the router delivery of the router at network segment place to destination network segment by, what each bar in the routing table write down expression is possible delivery path;

(1.2) in concentrator and routing table, respectively deposit " network segment node low order address---a place phase place correspondence table " all identical in to same network segment content and form, it is successively by the low order address of user node with use A respectively, B, C represents, and the place phase place constitutes, so that directly packet by place phase place sent to this node when destination address is the node of this network segment at concentrator or router receiving;

(2) the computer information that will be delivered to packet which node is passed to concentrator together with this packet through order wire with the form of destination address;

(3) after concentrator becomes the carrier communication bag to packet, learn the delivery network segment of the router that destination address will pass through and the router low order address of the network segment that needs to deliver by the retrieval routing table, transmit so that give the router of delivering the network segment packet;

(4) routing table of this network segment of retrieval after the router of the delivery network segment is received is learnt the delivery network segment of the router that destination address will pass through and the router low order address of the network segment that needs delivery, packet is given the router of the next stage delivery network segment and is transmitted; After the router of the final purpose network segment is received packet, retrieve " network segment node low order address---the place phase place correspondence table " of this network segment, this router just is delivered to packet by the place phase place network node at destination address place.

4. low-voltage network spread-spectrum communications system according to claim 3 and the method that designs, it is characterized in that: at described initial phase, distinguish in user's the network in strictness, to in concentrator, set up one " user ID (Identification; promptly identify)---address translation table ", it also is that the unique and identification number ID that remains unchanged for a long period of time and the network node address two parts at this user place are formed by what form with the numeral two 0 to 255 for each user successively, so that concentrator is learnt the network node address at user place by user ID information.

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