KR101207445B1 - Dynamic Channel Allocation System and Method for Avoiding Frequency Interference - Google Patents

Abstract

The channel dynamic allocation method that avoids frequency interference is performed when the channel dynamic allocation system using the ubiquitous sensor network (USN) and Wi-Fi (Wireless Fidelity, WiFi) is activated when the USN module and the WiFi module are activated. And, the USN module sends a message to the surrounding USN mortgage and determine the USN mortity information according to the response, and analyzes the WiFi frequency channel and the USN frequency channel to analyze the USN frequency channel interfered with the WiFi frequency channel In the detecting step, the WiFi module detects channel scan information of the WiFi access point by searching for nearby WiFi communication channels, and detects the remaining USN frequency channels except for the USN frequency channel that receives interference corresponding to the channel scan information. Transmitting and Changing USN Motes USN Frequencies with USN Frequency Channels Changing the channel to control transmission of data.

Description

Dynamic Channel Allocation System and Method for Avoiding Frequency Interference

The present invention is a channel dynamic allocation method, in particular, when using a ubiquitous sensor network (USN) and Wi-Fi (Wireless Fidelity, WiFi) at the same time, a channel for dynamically allocating channels by searching for frequencies to avoid frequency interference A dynamic allocation system and method.

In the ubiquitous environment, the wired system is replaced by ubiquitous sensor network (USN) communication or Wi-Fi (Wireless Fidelity, WiFi) communication, and a lot of research is being conducted to develop a system using ubiquitous wireless communication.

Compared to the existing wired system, the preference for ubiquitous wireless communication system is increasing due to the reduction of cable installation cost and maintenance cost.

The development and research of such ubiquitous wireless communication system is being activated, and USN and WiFi used for the ubiquitous wireless communication use the same Industrial Scientific and Medical Equipment (ISM) band 2.4Ghz frequency so that each communication system can be used in the same environment. The frequency interference in the construction affects the stability and reliability of the data transmission, making it difficult to communicate smoothly, causing problems in the real-time monitoring system.

In the conventional instrumented wireless communication system, a WiFi communication system using WiFi communication is installed, and a USN communication system is recently introduced.

For example, in the harbor terminal, Y / T, Q / C, T / C operators moving to the terminal yard in the port terminal operating room transmit work orders by using the wireless communication system until 2000. It is built and used.

When a separate USN communication system is introduced in such an environment, the communication of the WiFi communication frequency built into the port affects the reliability and transmission time of data transmission of the USN communication system, thereby preventing smooth communication.

Frequency allocation for each WiFi channel consists of channels 1 to 13 as shown in [Table 1] below, and frequency allocation for each USN channel consists of channels 11 to 26 as shown in [Table 2] below. Doing.

WiFi Channel Center frequency (MHz) Frequency domain (MHz) One 2412 2339.5 ~ 2424.5 2 2417 2404.5 ~ 2429.5 3 2422 2409.5-2434.5 4 2427 2414.5-2439.5 5 2432 2419.5 ~ 2444.5 6 2437 2424.5 ~ 2449.5 7 2442 2429.5 ~ 2454.5 8 2447 2434.5-2459.5 9 2452 2439.5-2464.5 10 2457 2444.5 ~ 2464.5 11 2462 2449.5-2474.5 12 2467 2454.5-2479.5 13 2472 2459.5 ~ 2484.5

USN Channel Center frequency (MHz) Frequency domain (MHz) 11 2405 2403.5 ~ 2406.5 12 2410 2408.5 ~ 2411.5 13 2415 2413.5 ~ 2416.5 14 2420 2418.5 ~ 2421.5 15 2425 2423.5 ~ 2426.5 16 2430 2428.5-2431.5 17 2435 2433.5-2436.5 18 2440 2438.5 ~ 2441.5 19 2445 2443.5 ~ 2446.5 20 2450 2448.5 ~ 2451.5 21 2455 2453.5 ~ 2456.5 22 2460 2458.5 ~ 2461.5 23 2465 2463.5 ~ 2466.5 24 2470 2468.5 ~ 2471.5 25 2475 2473.5 ~ 2476.5 26 2480 2478.5 ~ 2481.5

Referring to Tables 1 and 2, the frequencies of the USN communication system and the WiFi communication system are illustrated in FIG. 1.

Referring to FIG. 1, five to six channels of the USN overlap one WiFi channel, and the results are shown in Table 3 below.

WiFi Channel Interfering USN Channels One 11, 12, 13, 14, 15 2 11, 12, 13, 14, 15, 16 3 12, 13, 14, 15, 16, 17 4 13, 14, 15, 16, 17, 18 5 14, 15, 16, 17, 18, 19 6 15, 16, 17, 18, 19, 20 7 16, 17, 18, 19, 20, 21 8 17, 18, 19, 20, 21, 22 9 18, 19, 20, 21, 22, 23 10 19, 20, 21, 22, 23 11 20, 21, 22, 23, 24, 25 12 21, 22, 23, 24, 25, 26 13 22, 23, 24, 25, 26

Table 3 shows the USN channel interfered with the WiFi channel.

As described above, in the system using the USN and the WiFi communication at the same time, there is a problem that the frequency interference between each other can not process data in real time.

In order to solve this problem, an object of the present invention is to dynamically allocate a channel by searching for a frequency for avoiding frequency interference in a system using USN and WiFi simultaneously.

According to an aspect of the present invention, a channel dynamic allocation method for avoiding frequency interference is applied to a channel dynamic allocation system using ubiquitous sensor network (USN) and Wi-Fi (Wireless Fidelity, WiFi) simultaneously. Activating the USN module and the WiFi module when power is applied; The USN module transmitting a message to neighboring USN mortgages and grasping USN mortise number information according to whether or not a response is made; Analyzing a WiFi frequency channel and a USN frequency channel to detect a USN frequency channel interfering with the WiFi frequency channel; The WiFi module detects channel scan information of a WiFi access point by searching for a nearby WiFi communication channel and detects a remaining USN frequency channel except for an interrupted USN frequency channel corresponding to the channel scan information to detect the surrounding USN mote. Transmitting to the network; And changing the USN channel of the neighboring USN modems to the changed USN frequency channel to transmit data.

According to an aspect of the present invention, a channel dynamic allocation system that avoids frequency interference transmits a message to neighboring ubiquitous sensor network (USN) modems and forms a USN network by identifying USN number count information according to a response. A USN module; A WiFi module for detecting channel scan information of a WiFi access point by searching for a nearby WiFi Fidelity (WiFi) communication channel; And analyzing a WiFi frequency channel and a USN frequency channel to detect a USN frequency channel interfering with the WiFi frequency channel, and detecting a remaining USN frequency channel except for the interfering USN frequency channel corresponding to the channel scan information. And a control unit for transmitting data to the surrounding USN modems and transmitting data by changing the USN channels of the surrounding USN modems to the changed USN frequency channel.

By the above-described configuration, the present invention has an effect that can process data in real time without frequency interference between each other in a system using the WiFi and USN communication at the same time.

According to the present invention, when the real-time monitoring system is wired and replaced by a system using wireless communication, the construction cost and system maintenance cost can be reduced.

According to the present invention, if the frequency interference is detected and the frequency channel is dynamically changed, the wireless communication system can be constructed to secure the safety and reliability of data transmission even when using different communication systems at the same time.

FIG. 1 is a diagram illustrating a USN frequency channel superimposed on a WiFi frequency channel.
2 is a block diagram showing an internal configuration of a channel dynamic allocation system using USN and WiFi communication simultaneously to avoid frequency interference according to an embodiment of the present invention.
3 is a diagram illustrating a channel dynamic allocation method for avoiding frequency using a channel dynamic allocation system according to an embodiment of the present invention.
4 is an algorithm for searching for a nearby WiFi frequency channel and extracting and transmitting a USN frequency channel that is not subjected to interference based on the retrieved WiFi channel information in order to avoid frequency collision in the channel dynamic allocation method according to an embodiment of the present invention. It is a diagram showing.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

2 is a block diagram showing an internal configuration of a channel dynamic allocation system using USN and WiFi communication simultaneously to avoid frequency interference according to an embodiment of the present invention.

The channel dynamic allocation system 100 according to the embodiment of the present invention includes a USN module 110, a WiFi module 120, a controller 130, and a database unit 140.

The USN module 110 forms a USN network by sending a message to the surrounding USN mortgage and grasping the USN mort number information according to the response.

The WiFi module 120 detects channel scan information of the WiFi access point by searching for nearby WiFi communication channels.

The controller 130 analyzes the WiFi frequency channel and the USN frequency channel to detect a USN frequency channel that is interfered with the WiFi frequency channel.

The controller 130 analyzes the WiFi frequency channel and the USN frequency channel to detect a USN frequency channel interfering with the WiFi frequency channel (hereinafter, Tables 4, 5, and 6), and based on the interference, detects the interference with the WiFi frequency channel. Detect unused USN frequency channels.

The controller 130 detects the remaining USN frequency channel except for the USN frequency channel that receives the interference corresponding to the channel scan information of the WiFi access point, and transmits the changed USN frequency channel to the neighboring USN modems. Subsequently, the controller 130 changes the USN frequency channel of the surrounding USN modems to the changed USN frequency channel and transmits the data to the changed USN frequency channel.

The database unit 140 stores a database of USN frequency channels that do not interfere with the WiFi frequency channels detected by the controller 130.

3 is a diagram illustrating a channel dynamic allocation method for avoiding frequency using a channel dynamic allocation system according to an embodiment of the present invention.

In the channel dynamic allocation system 100 in which WiFi and USN communication are used at the same time, when the power is applied, the USN module 110 and the WiFi module 120 are activated (S100 and S102).

The USN module 110 transmits a hello message to the surrounding USN mortgages, receives an Ack message from the surrounding USN mortgage, determines the USN mort information, and then forms a USN network (S104). , S106, S108).

At this time, the USN network formed does not require real-time data transmission, so even if frequency interference occurs, the USN network is formed.

However, if data is transmitted based on the formed USN network, up to 50% of data transmission failure (Loss) occurs.

This is obtained through direct experiments, as shown in the following [Table 4] and [Table 5].

It is known that 26 of the USN frequency channel does not interfere with the WiFi frequency channel, but the results of the experiments of Tables 4 and 5 confirm that the USN 26 channel also interferes with the WiFi frequency channel.

Summarizing the experimental results as described in the following [Table 6] summarizes the interference channel per WiFi frequency channel.

The WiFi module 120 searches for a nearby WiFi communication channel (S110), and an example of the search result is derived as follows.

Cell 01-Address: 00: 30: 0D: 26: D5: 3B

          Protocol: 802.11b / g

          ESSID: "NESPOT

          Mode: Managed

          Channel: 1

     Link Quality: 47/100 Signal level: -71dBm Noise level: -87 dBm

          Encryption key: off

Bit Rates: 18Mb / s

Cell 02-Address: 00: 30: 0D: 26: 6D: 43

          Protocol: 602.11b / q

          ESSID: "NESPOT

          Mode: Managed

          Channel: 1

     Link Quality: 100/100 Signal level: -43dBm Noise level: -87 dBm

          Encryption key: off

          Bit Rates: 18Mb / s

Cell 03, Cell 04 ...

In this way, information of nearby WiFi access points (APs) is detected, and channel scan information used in each WiFi AP can be known.

The controller 130 stores the WiFi channel scan information and sequentially detects uninterrupted USN frequency channels by comparing with the database of previously stored uninterrupted USN frequency channels (S112 and S114).

Before storing the information of the WiFi AP, the controller 130 first excludes the information of the AP whose Link Quality is less than 50 from the information of the WiFi AP.

The reason is that the WiFi AP having a Link Quality of less than 50 does not communicate and is located at a considerable distance from the channel dynamic allocation system 100.

In the experiment results, it was confirmed from the experiment that the farther distance between the WiFi AP and the USN mote, the weaker the frequency interference and the link quality was not affected by the frequency interference in the AP less than 50.

Without this information, it is difficult to detect USN frequency channels that are not exactly interfered. To do this, Link Quality discards the WiFi AP information below 50 without storing it.

Cell 02 has Link Qulity of 100 and Channel 1. The USN frequency channels that are interfering with the WiFi AP are 11, 12, 13, 14, and 16, and 11 to 26 detect and store the remaining channels except the corresponding channel among the channels, and then sequentially USN through the WiFi AP information. The frequency channel is searched and the last detected channel information is stored.

The controller 130 transmits the detected USN channel information to the surrounding USN motes, and the USN motes receiving the USN channel information transmit an Ack message indicating that they have received the channel information to the controller 130 (S116 and S118). .

The controller 130 checks the number of Ack messages and confirms that USN channel information is correctly transmitted. If the number of Ack messages is abnormal, the controller 130 retransmits and retransmits the number of Ack messages until the same number of Ack messages is the same (S120). .

After determining that the USN channel information is normally transmitted, the controller 130 transmits a channel change command to the surrounding USN modems through wireless remote (Over the Air, OTA) technology, and the USN of the channel dynamic allocation system 100. The frequency channel is also changed (S122, S124).

The control unit 130 in which the USN frequency channel has been changed transmits a Hellow message to neighboring USN modems and receives an Ack message to form a USN network (S126 and S128). At this time, the controller 130 checks whether the number of USN mort formed is the same as the number of USN mort formed previously, if not, and transmits a channel change command again to form a USN network (S130, S132).

After the normal formation, the controller 130 controls to transmit data by transmitting a sensing data transmission command to the USN mote (S134, S136).

FIG. 4 shows a channel dynamic allocation system 100 using both USN and WiFi communication at the same time, searching for neighboring WiFi frequency channels and extracting USN frequency channels that are not subject to interference based on the retrieved WiFi channel information. It shows the algorithm to deliver.

The embodiments of the present invention described above are not implemented only by the apparatus and / or method, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (8)

Activating a USN module and a WiFi module when power is applied to a channel dynamic allocation system using a ubiquitous sensor network (USN) and Wi-Fi (Wireless Fidelity, WiFi) at the same time;
The USN module transmitting a message to neighboring USN mortgages and grasping USN mortise number information according to whether or not a response is made;
Analyzing a WiFi frequency channel and a USN frequency channel to detect a USN frequency channel interfering with the WiFi frequency channel;
The WiFi module detects channel scan information of a WiFi access point by searching for a nearby WiFi communication channel and detects a remaining USN frequency channel except for an interrupted USN frequency channel corresponding to the channel scan information to detect the surrounding USN mote. Transmitting to the network; And
Controlling to transmit data by changing the USN frequency channel of the surrounding USN modems to the changed USN frequency channel;
Including;
A method for dynamically assigning a channel to avoid frequency interference, wherein a WiFi access point having a link quality of less than 50 does not detect channel scan information and does not detect a USN frequency channel. The method of claim 1,
Identifying the USN mort number information,
The USN module sending a first hello message to the surrounding USN modems; And
Receiving a first Ack message from the surrounding USN mortise (Ack Message) to determine the USN mort information and to form a USN network
And a channel dynamic allocation method for avoiding frequency interference. The method of claim 2,
The step of transmitting to the surrounding USN Mort,
Whether or not to transmit the changed USN frequency channel is characterized by retransmitting until the number of second Ack messages received from the surrounding USN modems is equal to the first Ack message. How to avoid channel dynamic allocation. delete A USN module configured to transmit a message to surrounding Ubiquitous Sensor Network (USN) modems and determine USN number information according to whether a response is made to form a USN network;
A WiFi module for detecting channel scan information of a WiFi access point by searching for a nearby WiFi Fidelity (WiFi) communication channel; And
Analyzing the WiFi frequency channel and the USN frequency channel to detect the USN frequency channel interfering with the WiFi frequency channel, and detecting the remaining USN frequency channel except for the interfering USN frequency channel corresponding to the channel scan information. A control unit for transmitting data to the USN modems of the USN modems and transmitting data by changing the USN frequency channels of the neighboring USN modems to the changed USN frequency channels;
Including;
And the controller does not detect channel scan information of a WiFi access point having a link quality of less than 50 and does not detect a USN frequency channel. The method of claim 5,
The controller analyzes the WiFi frequency channel and the USN frequency channel to detect a USN frequency channel interfering with the WiFi frequency channel, and stores a database of USN frequency channels that do not interfere with the WiFi frequency channel. And a channel dynamic allocation system for avoiding frequency interference. The method according to claim 6,
The controller detects each channel scan information of each WiFi access point through the WiFi module, and compares each WiFi channel scan information with the USN frequency channel that does not receive the database-based interference, thereby not receiving any interference. A channel dynamic allocation system for avoiding frequency interference, characterized by detecting information sequentially. delete

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