JP2012114652A - Wireless lan system, access point for wireless lan and control program for access point - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless LAN system that can obtain enough power at a periphery of an output end of an LCX cable and improve security even when using the LCX cable.SOLUTION: A wireless LAN system includes a first and a second leaky coaxial cables 41, 42 installed along a longitudinal direction of a straight long communication area; a first access point 11, in which an antenna terminal is connected to one end side of the first leaky coaxial cable 41, which exchanges data with a server 30; and a second access point 12, in which an antenna terminal is connected to the other end side of the second leaky coaxial cable 42, which exchanges data with the server 30. The wireless LAN system enables communication with the server 30 in an overlapping section between the communication area of the first leaky coaxial cable 41 and the communication area of the second leaky coaxial cable 42.

Description

  Embodiments described herein relate generally to a wireless LAN system using a leaky coaxial cable. Furthermore, the present invention relates to a wireless LAN access point and an access point control program used in this system.

  A wireless LAN system using a leaky coaxial cable is considered to have higher security than a general wireless LAN system because radio waves are emitted only in the periphery of the cable.

  The radiation of the radio wave in the leaky coaxial cable is strong near the input end of the leaky coaxial cable, and when it is near the output end, the radiation is weakened due to transmission loss of the cable. As for the transmission loss, as in the case of a general coaxial cable, if it is made thin and soft for the sake of convenience, the transmission loss becomes larger, and the tendency that the difference in radiation between the input end and the output end becomes larger. Further, in the leaky coaxial cable, the directivity of the main radiation beam tends to be inclined by about 20 ° to 25 °. Therefore, in the vicinity of the output end, a phenomenon called a terminal effect occurs in which the other party cannot obtain sufficient power.

  For the above reasons, if the power applied to the input end is increased in order to obtain sufficient power even near the output end of the leaky coaxial cable, the radiation area near the input end becomes wider and the security is lowered. On the other hand, if security is emphasized and radiation near the input end of the leaky coaxial cable is to be suppressed, there is a problem that it is difficult to connect wirelessly near the output end.

JP 2007-135151 A

  One embodiment of the present invention provides a wireless LAN system capable of obtaining sufficient power near the output end of a cable and improving security even when a leaky coaxial cable is used. Also provided are a wireless LAN access point and an access point control program used in the above wireless LAN system.

  According to the embodiment, in a wireless LAN system using a leaky coaxial cable, the first and second leaky coaxial cables arranged in parallel along the longitudinal direction of a communication area that is long in one direction, and the first leaky coaxial cable An antenna terminal is connected to one end of the cable, a first access point that exchanges data with the server, and an antenna terminal is connected to the other end of the second leaky coaxial cable. And a second access point for exchanging data between them. Then, communication with the server is enabled at an overlapping portion of the communication area of the first leaky coaxial cable and the communication area of the second leaky coaxial cable.

1 is a schematic configuration diagram showing a wireless LAN system according to a first embodiment. The figure which shows the communication area at the time of using one leaky coaxial cable. The figure which shows the communication area at the time of using two leaky coaxial cables. 6 is a flowchart for explaining the operation of the wireless LAN system of the first embodiment. 1 is a perspective view illustrating an example in which a wireless LAN system according to a first embodiment is applied to an office desk. The schematic block diagram which shows the wireless LAN system concerning 2nd Embodiment. The block diagram which shows the structure of the access point for wireless LAN used for 2nd Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram showing a wireless LAN system according to the first embodiment.

  Access points 10 (first access point 11 and second access point 12) are installed on one side and the other side across a desired communication area, and each access point 11 and 12 is connected to server 30 via controller 20. It is connected.

  One end of a leaky coaxial cable (hereinafter abbreviated as LCX cable) 41 is connected to the antenna terminal of the first access point 11, and the other end of the LCX cable 41 extends to the vicinity of the second access point 12. . One end of the LCX cable 42 is connected to the antenna terminal of the second access point 12, and the other end of the LCX cable 42 extends to the vicinity of the first access point 11. That is, two LCX cables 41 and 42 are arranged in parallel along a communication area that is long in one direction. Here, the first and second access points 11 and 12 use different channels (different frequencies).

  As shown in FIG. 2, in the wireless LAN system using the LCX cable 40, the communication area is only the peripheral portion of the cable 40, so that the security is higher than that of a general wireless LAN system. However, the communication area between one LCX cable 40 and one access point 10 is large near the input end of the LCX cable 40 and becomes smaller as it approaches the output end. For this reason, in the vicinity of the output end of the LCX cable 40, a phenomenon called a terminal effect occurs in which the other party cannot obtain sufficient power. That is, near the output end of the LCX cable 40, it becomes difficult to connect wireless. This problem does not occur if a sufficiently large amount of power is supplied to the input end of the LCX cable 40, but in this case, the communication area near the input end expands in the horizontal direction, leading to a decrease in security.

  On the other hand, as in the present embodiment, when two LCX cables 41 and 42 and two access points 11 and 12 are installed and the LCX cables 41 and 42 are fed from opposite directions, these communication areas overlap. The region is as shown in FIG. That is, the overlapping area 48 of the communication area 46 by the LCX cable 41 and the communication area 47 by the LCX cable 42 becomes a communication area, and the area expansion near the input end (feeding end) of the LCX cable can be suppressed. Therefore, it is possible to prevent unnecessary expansion of the communication area near the input ends of the LCX cables 41 and 42 by enabling communication only when the client side receives signals from both access points 11 and 12. Can improve communication security.

  Next, the operation of the present embodiment will be described with reference to the flowchart of FIG.

  First, it is determined whether or not the first access point 11 (AP1) is connected to the client (CL) (step S1). When the connection between AP1 and CL is confirmed in step S1, AP1 transmits information on the MAC address of CL to the controller 20 (step S2). Subsequently, the controller 20 transmits information on the MAC address to the second access point 12 (AP2) (step S3).

  Next, the AP 12 compares the MAC address of the connected CL with the MAC address previously sent from the controller 20 (step S4). Then, it is determined whether or not both addresses match (step S5).

  If it is determined in step S5 that both addresses match, communication between the AP 12 and the CL is permitted, and communication between the CL and the server 30 is executed (step S6). On the other hand, if it is determined in step S5 that the two addresses do not match, communication between AP2 and CL is blocked (step S7). Further, since the MAC address from the CL cannot be acquired by the AP 2 in the area that can be received by the AP 1 but cannot be received by the AP 2, the communication is blocked in the same manner as in the step S7. That is, only the CL in the communication area 48 shown in FIG. 3 can be communicated, and security can be improved.

  The above flowchart is an example of the operation, and can be modified as appropriate according to the specifications. In short, it is only necessary to permit communication only when the MAC address obtained at AP1 and the MAC address obtained at AP2 match. Further, regarding communication with the server 30 after confirming the MAC address, communication may be performed using only AP2, but communication speed may be improved by performing communication using both AP1 and AP2. Is possible.

  FIG. 5 is a perspective view showing an example in which the wireless LAN system of this embodiment is applied to an office desk. In the figure, 51 is a table that is long in one direction, 52 is a chair, and 53 is a personal computer equipped with a wireless LAN. LCX cables 41 and 42 are disposed along the longitudinal direction at the center of the table 51, and access points 11 and 12 are connected to one ends of the cables 41 and 42, respectively. The connection positions of the access points 11 and 12 with respect to the LCX cables 41 and 42 are opposite ends. Although not shown in the figure, the access points 1 and 12 are connected to the controller 20 via a LAN cable, and the controller 20 is further connected to the server 30 via a LAN cable.

  With such a configuration, the communication area can be an area along the longitudinal direction of the table 51, and only the personal computer placed on the table 51 can be communicated. For this reason, although it is wireless LAN, the security improvement similar to wired LAN can be aimed at.

  As described above, according to the present embodiment, since communication is enabled only when both signals from the two access points 11 and 12 are detected, security can be improved. In addition, it is possible to suppress an unnecessary expansion of the communication area in the vicinity of the input ends of the LCX cables 41 and 42, and it is possible to improve security.

(Second Embodiment)
FIG. 6 is a schematic configuration diagram showing a wireless LAN system according to the second embodiment. In addition, the same code | symbol is attached | subjected to FIG. 1 and an identical part, and the detailed description is abbreviate | omitted.

  This embodiment is different from the first embodiment described above in that power can be supplied from one access point to two LCX cables and the access point has a controller function.

  First and second LCX cables 41 and 42 are arranged along the longitudinal direction of the communication area that is long in one direction. The access point 100 has two antenna terminals, and each terminal can transmit and receive a radio frequency (RF) signal having a different frequency. One terminal is connected to one end of the LCX cable 41, and the other terminal is connected to the other end of the LCX cable 42. More specifically, for example, one terminal is directly connected to the LCX cable 41, and the other terminal is connected to the LCX cable 42 via a coaxial cable. The access point 100 is connected to the server 30 via a LAN cable.

  As shown in FIG. 7, for example, the access point 100 according to the present embodiment includes a MAC (Media Access Control) unit 110, a physical unit 120, a high frequency unit 130, and a control unit 140.

  The MAC unit 110 performs signal processing on packet data received from the server side and converts the frame data into frame data suitable for wireless communication. The MAC unit 110 performs signal processing, converts the frame data into packet data, and transmits the packet data to the server side. MAC receiving unit 112 is provided.

  The physical unit 120 performs signal processing on the frame data from the MAC transmission unit 111 and performs D / A conversion, and physical processing for analog signal processing and A / D conversion and transmission to the MAC reception unit 112. A receiving unit 122 is provided.

  The high-frequency unit 130 includes two RF transmission / reception units 131 and 132 in order to perform transmission / reception through two channels. The RF transmission / reception unit 131 (RF1) converts the analog signal from the physical transmission unit 121 into an RF signal, transmits the RF signal to the first LCX cable 41, and demodulates the RF signal from the LCX cable 41 to demodulate the physical reception unit 122. Transmit to. The RF transmission / reception unit 132 (RF2) converts the analog signal from the physical transmission unit 121 into an RF signal, transmits the RF signal to the second LCX cable 42, and demodulates the RF signal from the LCX cable 42 to demodulate the physical reception unit 122. Transmit to.

  The control unit 140 controls the MAC unit 110, the physical unit 120, and the high frequency unit 130. For example, the control unit 140 performs control so as to perform substantially the same operation as the flowchart of FIG. Specifically, communication is performed using RF1, and it is determined whether or not CL is connected (communicable) to the LCX cable 41 connected to RF1, and when the connection is confirmed, the MAC address of CL is acquired. Next, communication is performed using RF2, and it is determined whether or not CL is connected (communication is possible) to the LCX cable 42 connected to RF2, and when the connection is confirmed, the MAC address of CL is acquired. Then, the MAC address obtained by RF1 and the MAC address obtained by RF2 are compared, and if it is determined that both addresses match, communication between the access point 100 and CL is permitted, and the CL and server 30 Communicate with the. On the other hand, if it is determined that the two addresses do not match, communication between the access point 100 and the CL is blocked. That is, the CL MAC address obtained by RF1 is compared with the CL MAC address obtained by RF2, and communication is enabled only when both addresses match.

  As described above, according to the present embodiment, there is one access point 100, but power is supplied from one and the other to the two LCX cables 41 and 42 in the same manner as in the first embodiment. Expansion of useless communication areas near the input ends of 41 and 42 can be suppressed. Therefore, the same effects as those of the first embodiment can be obtained, and since the access point can be made one, the system configuration can be simplified.

(Modification)
The present invention is not limited to the above-described embodiments. In the embodiment, the signals supplied to the two LCX cables are different channels (RF signals having different frequencies). However, it is not always necessary to change the frequencies of the two LCX cables. May be performed.

  In the embodiment, power is supplied from two different directions to the two LCX cables. However, power can be supplied from the same direction. In this case, expansion of the communication area near the input end cannot be suppressed, but it is possible to improve security by confirming the MAC address of the client by two communication means.

  Further, the access point control described in the embodiment does not necessarily have to be processed in hardware by the controller or the control unit, and can be processed in software. For example, as a program that allows the CPU to execute control of the access point, for example, it is written in a recording medium such as a magnetic disk (FD, HD, etc.), an optical disk (CD-ROM, DVD, etc.), a semiconductor memory, etc. It is also possible to apply to various devices by transmitting through a communication medium. The CPU that realizes the control of the access point only needs to read the program recorded in the recording medium, the communication medium, etc., and execute the above-described processing by controlling the operation by this program. Furthermore, it is possible to control the access point by such a program on the server side.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 (11, 12), 100 ... access point 20 ... controller 30 ... server 40 (41, 42) ... leaky coaxial cable (LCX cable)
45, 46, 47, 48 ... communication area 51 ... table 52 ... chair 53 ... personal computer 110 ... MAC unit 111 ... MAC transmission unit 112 ... MAC reception unit 120 ... physical unit 121 ... physical transmission unit 122 ... physical reception unit 130 ... high frequency Unit 131, 132 ... RF transceiver 140 ... Control unit

Claims (6)

First and second leaky coaxial cables arranged in parallel along the longitudinal direction of the communication area long in one direction;
An antenna terminal connected to one end of the first leaky coaxial cable, and a first access point for transferring data to and from the server;
An antenna terminal connected to the other end of the second leaky coaxial cable, and a second access point for exchanging data with the server;
Comprising
A wireless LAN system that enables communication with the server at an overlapping portion between a communication area of the first leaky coaxial cable and a communication area of the second leaky coaxial cable.   2. The wireless LAN system according to claim 1, wherein the first and second access points perform signal transmission with respect to the leaky coaxial cable at different frequencies or in a time division manner. The first and second access points are connected to the server via a controller;
The MAC address of the client obtained at the first access point and the MAC address of the client obtained at the second access point are compared by the controller, and when the MAC addresses are the same, the client and the server 3. The wireless LAN system according to claim 1, wherein communication with a wireless LAN is permitted. First and second leaky coaxial cables arranged in parallel along the longitudinal direction of the communication area long in one direction;
A first antenna terminal is connected to one end of the first leaky coaxial cable, and a second antenna terminal is connected to the other end of the second leaky coaxial cable to exchange data with a server. An access point to perform,
Comprising
A wireless LAN system characterized in that communication with the server is enabled at an overlapping portion of a communication area of the first leaky coaxial cable and a communication area of the second leaky coaxial cable. A MAC unit for performing conversion between packet data provided for data communication with the server and frame data provided for wireless communication;
A physical unit that D / A converts the frame data from the MAC unit to generate an analog signal, and supplies frame data obtained by A / D conversion of the analog signal to the MAC unit;
A transmission / reception unit connected to the physical unit for converting the frame data and the high-frequency signal, and for transmitting and receiving two high-frequency signals;
An antenna terminal connected to the transceiver unit for connecting two leaky coaxial cables corresponding to the two systems;
While controlling the MAC unit, the physical unit, and the transmitting / receiving unit, the MAC address of the client input via one of the leaky coaxial cables is the same as the MAC address of the client input via the other of the leaky coaxial cables A control unit that permits communication with the server in a case;
An access point for wireless LAN, comprising: A program for performing control of an access point of the wireless LAN system according to claim 3 by a computer,
A procedure for transmitting the MAC address of the client to the controller after confirming the connection between the first access point and the client;
A procedure for transmitting a MAC address to the second access point by the controller;
After confirming the connection between the second access point and the client, a procedure for comparing the MAC address of the client with the MAC address sent from the controller;
Allowing communication between the client and the server when the MAC addresses match;
A computer-readable control program for an access point for causing a computer to execute the program.

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