KR101511500B1 - The quickly and effectively data process and collision avoidance method in Power Line Communication - Google Patents

Abstract

If the number of users is increased and a subcarrier is used in a limited bandwidth in an existing OFDMA communication method in a power line communication, the possibility of a data collision and interference between channels are increased. Due to the problems, the communication quality is reduced and the data processing speed is delayed. Power consumption due to data retransmission is increased. To solve the problems, the present invention prevents the collision between the channels due to the use of the same subcarrier in an adjacent device by sharing and receiving the subcarrier with a low load or allocating different sub carriers in adjacent AP terminals, minimizes a data loss due to the data collision, and prevents the delay problem of the data processing speed due to a lot of loads by connecting a plurality of nodes to the AP terminal by limiting the number of the subcarriers.

Description

Technical Field [0001] The present invention relates to a data processing apparatus and a collision avoidance method in a power line communication,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of quickly and efficiently processing data of an AP in a system using a plurality of subcarriers using an orthogonal frequency division multiple access (OFDMA)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power line communication method, and more particularly, to a method of rapidly and efficiently processing data of an AP in a system using a plurality of sub-carriers in an OFDMA communication method.

Generally, Power Line Communication (PLC) is a method of communicating data by power line using commercial AC signal as a transmission medium. All the power lines in the home, the office, or the factory become communication lines because the communication is carried out with a center frequency (carrier) in a sinusoidal wave of 60 Hz which is a commercial AC power source. Therefore, there is an advantage in that a communication network can be constructed without installing a separate communication line, and a power line communication (PLC) is provided to remotely control a plurality of devices or devices (hereinafter, referred to as peripheral devices) Is widely used. That is, these power line communication (PLC) are applied to automatic meter reading (AMR), home automation (HA), building automation, and factory automation (FA). The AMR is an energy meter that measures the amount of energy used by households and companies, such as electricity, water, hot water, and gas, Is used to refer to a remote management company. In recent years, an automatic meter reading system has been emerging that performs remote meter reading of waterworks, gas, electricity, and the like through a web-based Internet. Home automation (HA) refers to remote monitoring and control of various information appliances such as a home or an apartment. (Heating, Ventilation & Air Conditioning, HVAC) such as security devices such as home lighting, Internet information appliances, gas, fire and security sensors and CCD cameras, air conditioners, / Video (audio / video) devices (hereinafter referred to as peripheral devices for HA) can all be subject to remote monitoring and control. In recent years, home automation server has introduced a technology for integrating, processing, and managing information generated from peripheral devices for home use in the home through the Internet. The user can control the peripheral device for home HA in the home and detect the abnormal state from a remote place by using a general personal computer (PC), a mobile phone, a PDA or the like. In the case of existing houses, it is difficult to additionally install a communication line for communication between information devices. Therefore, there is a need for a technology using various wired / wireless communication methods such as HomePNA communication, radio frequency (RF) . In the building automation system, the power line communication method is used to remotely monitor the elevator operation status and floor lighting status in the building. In factory automation (FA) systems, power line communication systems are used to remotely control NC machine tools, industrial robots, and various sensors (hereinafter referred to as FA peripheral devices) that can automate production lines.

The OFDMA scheme has recently been widely adopted as a high-speed data transmission scheme in wired / wireless communication. This scheme is robust to frequency selective fading channels, has high frequency utilization efficiency, and is resistant to unexpected specific impulse noise. Therefore, it can be said that it is the most suitable communication method for narrowband power line communication in which allocated frequency resources are narrow and exposed to a lot of noisy environments. On the other hand, since the communication is performed in a random access manner, the possibility of data collision increases when the number of users increases in a limited bandwidth and the use of the sub-carrier increases. Therefore, problems such as a decrease in communication quality and a delay in data processing due to such problems occur.

The present invention proposes a solution to solve this problem in power line communication. In the prior art, all nodes and APs share all subcarriers in a given band and perform communication by allocating channels randomly. Since many users use finite frequency resources at the same time, many data collisions occur, interference occurs between channels, and data processing time is delayed and power consumption due to data retransmission also increases.

In the power line communication, different subcarriers are allocated between adjacent APs to restrict the use of the same subcarrier in adjacent devices, thereby preventing interchannel collision and minimizing data loss due to data collision. In addition, since the number of subcarriers is limited, a problem in which a large number of nodes are connected to an AP and a data processing speed due to a large load is delayed can be solved.

Prior art literature

US 2014/0036976 A1

US 2012/0320995 A1

KR 10-2008-0090602 A

KR 10-2005-0098614 A

KR 10-2006-0038564 A

In the conventional OFDMA communication method in the power line communication method, when the number of users increases within a limited bandwidth, the possibility of data collision increases and the interchannel interference increases when the use of the sub-carrier increases. Therefore, the communication quality degradation and data processing speed are delayed due to these problems, and power consumption due to data retransmission also increases.

In order to solve such a problem, the present invention proposes a method of allocating different subcarriers between adjacent APs or allocating subcarriers sharing a small load, thereby preventing a collision between channels due to the use of the same subcarrier in an adjacent device as much as possible, Minimize data loss. In addition, since the number of subcarriers is limited, a problem in which a large number of nodes are connected to an AP and a data processing speed due to a large load is delayed can be solved.

  The OFDMA scheme has recently been widely adopted as a high-speed data transmission scheme in wired / wireless communication. This scheme is robust to frequency selective fading channels, has high frequency utilization efficiency, and is suitable for high-speed data communication. On the other hand, when the number of users is increased in a limited band due to the random access method, the possibility of data collision increases and interchannel interference increases. Therefore, problems such as a decrease in communication quality, a delay in data processing speed, and an increase in power consumption due to data retransmission are caused by these problems.

In order to solve this problem, different subcarriers are allocated between adjacent APs to restrict the use of the same subcarrier in adjacent devices, thereby preventing interchannel collision and minimizing data loss due to data collision. In addition, since the number of subcarriers is limited, a problem in which a large number of nodes are connected to an AP and a data processing speed due to a large load is delayed can be solved.

The present invention also provides an economical aspect such as reduction of maintenance cost due to reduction of power consumption due to improvement of communication quality.

1 is a schematic system block diagram of power line communication configured in the present invention.
2 is a diagram showing frequency distributions of subcarriers SC1 to SC15 in the OFDMA scheme, which is a power line communication scheme proposed by the present invention
FIG. 3 is a diagram illustrating an example in which OFDMA frequency division used in conventional power line communication is allocated for communication.
FIG. 4 is a diagram showing an example of communication by allocating frequency division of the OFDMA scheme proposed in the present invention.
FIG. 5 is a flowchart illustrating a procedure for allocating a channel group to an AP by dividing a sub-carrier in the OFDMA power-line communication proposed in the present invention.

      Disclosed is a method for improving communication quality by minimizing frequency interference between each network based on a network composed of APs and nodes by separating sub-carriers of OFDMA in power line communication and eliminating excessive load on each network. .

 The present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic system block diagram of power line communication configured in the present invention.

  As shown in the figure, the basic configuration includes a server 10 for storing and managing data, a gateway 20 for delivering data received from the AP to the server 10 in accordance with the network network structure, (40 ~ 43) for transmitting sensor data to the gateway (20), node nodes (An ~ Hn) for transmitting the data received from the probe or sensor to the AP, and transformers (30 ~ 37) do.

2 is a diagram showing frequency distributions of subcarriers SC1 to SC15 in the OFDMA scheme, which is a power line communication scheme proposed by the present invention. The subcarriers SC1, SC4, SC5 and SC13 are subcarriers allocated to the AP1. SC2, SC3, SC9 and SC12 are the subcarriers allocated to the AP2 and the subcarriers SC5, SC8, SC11 and SC15 are the subcarriers allocated to the AP3. Is a jointly allocated subcarrier to AP1 and AP3.

The number of subcarriers varies from several tens to several thousand depending on the communication system. In OFDMA, as shown in FIG. 2, frequency overlap between subcarriers (SC1 to SC15) is allowed while maintaining a certain frequency separation distance. This is possible because a plurality of carriers having mutual orthogonality are used, the frequency utilization efficiency can be increased at a limited frequency resource, and is suitable for high-speed data transmission.

FIG. 3 is a diagram illustrating an example in which OFDMA frequency division used in conventional power line communication is allocated for communication. In the figure, the horizontal represents the time and the vertical represents the subcarriers.

In FIG. 3, all APs and all users communicate at random through all sub-carriers. In this case, the possibility of frequency collision becomes very high because all subcarriers share and use it.

FIG. 4 is a diagram showing an example of communication by allocating frequency division of the OFDMA scheme proposed in the present invention. In the figure, the horizontal represents the time and the vertical represents the subcarriers.

As shown in FIG. 4, for example, it is assumed that there are three APs, and subcarriers SC1, SC2, SC3, SC4, SC5, and SC6 exist. At this time, APs are allocated subcarriers from the gateway 20. The subcarrier groups allocated to AP1 are SC2, SC4, SC5 and SC6. The subcarrier groups allocated to AP2 are SC2, SC3, SC4 and SC5. The subcarrier groups allocated to AP3 are SC1, SC2, SC4 and SC5. Each node communicates only with the subcarriers assigned to the accessing AP. The number of APs may be different depending on the load applied to each AP, and redundant use is also possible. A large number of sub-carriers are allocated to a load-intensive AP, and a small number of sub-carriers are allocated to an AP having a low load. Duplicate use of subcarriers is also possible.

FIG. 5 is a flowchart illustrating a procedure for allocating a channel group to an AP by dividing a sub-carrier in the OFDMA power-line communication proposed in the present invention.

Referring to FIG. 5, the AP provides location information using GPS information to the gateway 20 (step 1). The gateway 20 looks up the location information and allocates a subcarrier to the corresponding AP in consideration of the surrounding environment, that is, a subcarrier that can avoid frequency collision (step 2). The AP transmits time synchronization information and channel information to a node which is a subsystem (step 3). The node confirms the signal strength (RSSI) of the AP and requests network connection to the desired AP (step 4). The AP grants the network connection (step 5). Through this procedure, the node confirms the information of the sub-carrier group allocated to the AP and starts communication using the group (step 6). Since the communication is performed through such a procedure, collision due to random access can be reduced.

10 servers
20 gateway

Claims (5)

A data processing apparatus for a power line communication AP, comprising: a server (10) for storing and managing data; A gateway 20 for transmitting the data received from the AP to the server 10 according to the network network structure; APs (40 to 43) for transmitting metering data or sensor data received from the data node to the gateway; Nodes (An-Hn) for transmitting the data received from the probe or sensor to the AP; And a transformer (30 to 37) for switching to a domestic voltage,
In the OFDM communication, subcarriers SC1, SC4, SC5 and SC13 are subcarriers allocated to AP1, subcarriers SC2, SC3, SC9 and SC12 are allocated to AP2, and subcarriers SC5, SC8, SC11 and SC15 are allocated to AP3 And the sub-carriers SC6, SC10, and SC14 are sub-carriers jointly allocated to AP1 and AP3.
delete The method of claim 1, wherein the number of subcarriers is several tens to several thousand according to a communication system, each subcarrier permits frequency overlap while maintaining a constant frequency spacing, And the AP-side data processing unit of the power line communication
A method of processing data in a power line communication AP stage, the sub-carriers SC1, SC2, SC3, SC4, SC5, and SC6 being present and the AP being allocated subcarriers from the gateway 20; The subcarrier groups allocated to AP1 are SC2, SC4, SC5 and SC6, the subcarrier groups allocated to AP2 are SC2, SC3, SC4 and SC5, and the subcarrier groups allocated to AP3 are SC1, SC2, SC4 and SC5; Wherein each node is configured to perform communication only with sub-carriers allocated to the accessing AP,
delete

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