JP2004023454A - Radio communication system and radio communication method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system etc., capable of effective use of a radio LAN system having high throughput by avoiding a hidden terminal problem in the radio LAN system. <P>SOLUTION: When a new mobile terminal is added to the radio communication system, an access point and each mobile terminal transmit response packets respectively, and judge a reception state of the newly added packet. Then, the access point and each mobile terminal notify the user about the judgement result. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication system such as a wireless LAN system having a plurality of mobile terminals and an access point wirelessly connected thereto.
[0002]
[Prior art]
A wireless local area network system (wireless LAN system) including a mobile terminal that performs communication using a wireless transmission path, and an access point that controls connection of the mobile terminal and connects between the mobile terminal and a wired network. ) Is conventionally known.
[0003]
This wireless LAN system is used as a highly portable network system that is not restricted by a communication cable. In recent years, in particular, an improvement in transmission speed in a wireless communication section, spread of a notebook computer, and applications suitable for mobile communication have been made. With the emergence of, etc., it is showing a dramatic spread. However, wireless LAN systems are generally wireless communication systems using radio waves, and low confidentiality and low reliability in communication have been pointed out.
[0004]
For example, due to the nature of radio waves, once transmitted from a transmitter into space, it can be intercepted by a third party other than the mobile terminal that is the destination, and communication data as information is transmitted to an external third party. There is a risk of leaking to others. In addition, the wireless LAN system is not logically connected to a wired LAN but physically connected by a wireless communication procedure to a base station that manages communication of mobile terminals. Therefore, there is a possibility that a mobile terminal outside the own organization may be connected to the network by mistake or intentionally.
[0005]
In order to prevent such a problem, various measures are taken in the wireless LAN system in each layer from an upper application layer to a lower MAC (Media Access Control) layer or a physical layer. In particular, it is common practice to deal with information leakage due to interception of wireless signals by encrypting data, etc., and to avoid these problems by adopting an authentication method for unauthorized external connections. is there.
[0006]
Further, the wireless communication path is different from a constantly stable communication method using a wired cable, and a large attenuation of radio waves occurs depending on a distance between a transmitter and a receiver, so that the communication quality of a received wireless signal greatly changes. Normally, in a wireless communication system, an automatic gain adjustment device is provided in a receiver circuit, and a demodulation process is performed after adjusting a received signal strength to an appropriate level even if the distance between the communication devices varies. As a result, it is generally possible to cover a wide geographical service area.
[0007]
However, when the distance between the transmitter and the receiver exceeds a certain limit, there is a section where communication becomes impossible due to a large attenuation of the radio signal strength. In particular, under an operation situation in which a large number of wireless terminals exist in a service area, a combination of terminals that can communicate with each other and terminals that cannot communicate occurs. Such a situation is called a hidden terminal problem.
[0008]
Generally, when a plurality of terminals communicate with each other using a carrier wave of the same frequency, a time division multiple access (TDMA) system in which each terminal performs communication in a time-division manner is used, and is self-owned in a premises or indoors. A similar method is used in a wireless LAN system operated as a communication network. More specifically, in a wireless LAN defined by the IEEE 802.11 standard, a collision-prevention type carrier sense multiple access method (CSMA-CA: A method called Carrier Sense Multiple Access-Collision Aidance is used. The CSMA-CA method is a kind of distributed control type access method, which enables multiple access by a relatively simple protocol, but has a disadvantage that the throughput of the entire network decreases particularly when the number of terminals increases. Have.
[0009]
According to the distributed coordination function defined in IEEE 802.11, a terminal that wants to transmit first transmits a radio signal to determine whether a radio signal from another terminal exists on a radio communication path. Perform reception. In this receiving operation, it is not necessary to perform demodulation of data modulated on the radio signal, and it is sufficient to recognize only the presence of the electromagnetic wave. Therefore, the signal level of the electromagnetic wave is obtained by envelope detection or the like. This operation is generally called carrier sense.
[0010]
FIG. 10 is a diagram illustrating a state of packet transmission according to the CSMA-CA access method.
[0011]
Now, there are three terminals A, B, and C on the network, and a packet is transmitted from the terminal A. At this time, it is assumed that the terminals B and C respectively hold packets to be transmitted. First, the terminals B and C try to detect a signal from another terminal by carrier sense. Here, when detecting the packet from the terminal A, the terminals B and C stand by until the transmission of the current packet ends. When the end of the packet is recognized, the carrier sense is further continued during a period described as DIFS (Distributed InterFrame Space) in the figure.
[0012]
In this distributed control method, each terminal on the network can transmit a packet after the end of the DIFS section. However, in the CSMA-CA method, in order to avoid collision of packets transmitted from a plurality of terminals at the same time, each terminal Continues carrier sense for a certain period of time determined by a random number. The operation of continuing carrier sense during this period is called back-off in this standard.
[0013]
For example, as shown in FIG. 10, when the back-off period of terminal B is shorter than the back-off period of terminal C, terminal B acquires the right to transmit a packet and starts transmitting the next packet. Once the transmission of the packet is started from the terminal B, the terminal C performs carrier sense for this packet, waits for the transmission until the end of the packet, and acquires the right to transmit the packet again in the next back-off period. You have to wait for your packet to be sent.
[0014]
In the distributed control method, the terminal transmitting the packet is determined as described above, and multiple access can be autonomously performed. Here, since the back-off time of each terminal is determined by a random number, the opportunity to transmit a packet is equally given to all terminals. As described above, in a distributed control system such as the CSMA-CA system, it is indispensable to accurately grasp the occupation state of the wireless communication channel by carrier sense. Packet collisions occur due to simultaneous transmission of packets and the like, causing a situation in which the throughput is significantly reduced.
[0015]
The hidden terminal that poses a problem here means that if there is a wireless terminal other than the one that is currently communicating, the carrier must be detected and its own signal transmission must be forgotten. A terminal that sends out a signal. As a conventional technique for preventing a decrease in throughput due to such a hidden terminal problem, there is a technique disclosed in Japanese Patent Laid-Open No. 6-232870. Here, the related art will be described with reference to FIG.
[0016]
First, in (1) in the figure, when the wireless terminal D is not powered on, it is assumed that the other wireless terminals A, B, and C can communicate with each other, and that there is no hidden terminal in the present network. . Here, after turning on the power, the wireless terminal D broadcasts a response request packet to another wireless terminal as shown in FIG. At this time, the wireless terminal A and the wireless terminal B can correctly receive the response request packet, but the wireless terminal C cannot normally receive the response request packet due to a large distance from the wireless terminal D. Here, the wireless terminal D is a hidden terminal for the wireless terminal C.
[0017]
Thereafter, for example, the wireless terminal A performs carrier sense and finds a time slot in which the wireless terminal A can transmit, and sends a direct response packet including the address information of the wireless terminal D to all the wireless terminals as shown in FIG. Broadcast to
[0018]
At this time, the wireless terminal C receives the direct response packet from the wireless terminal A in FIG. 3C, although the wireless terminal C has not received the response request packet in FIG. It recognizes that it cannot directly receive the packet from the wireless terminal D. Accordingly, the wireless terminal C sends an indirect response request packet to the wireless terminal D to the wireless terminal A in FIG.
[0019]
The wireless terminal A that has received the indirect response request packet sends an indirect response packet to the wireless terminal D as shown in FIG. The wireless terminal D that has received the indirect response packet recognizes that it is a hidden terminal when viewed from the wireless terminal C.
[0020]
The above operation is repeated, the number of received direct response packets and the number of received indirect response packets are counted, and if a predetermined relationship is satisfied, the wireless terminal C or the wireless terminal D in this example hides itself on the network. It recognizes that it is a terminal and starts to refrain from sending data packets from itself. In this conventional example, the participation of the hidden terminal in the network is suppressed in this manner, thereby preventing the throughput of the entire network from decreasing.
[0021]
[Problems to be solved by the invention]
However, in the above conventional example, a mobile terminal that has recognized that it is a hidden terminal simply does not perform subsequent communication, and is essential for the purpose of increasing the use efficiency of the entire wireless communication network and performing efficient operation. This is not a practical solution.
[0022]
Furthermore, as a method of determining a hidden terminal, the number of control packets transmitted based on the distributed control method is statistically counted, and it is difficult to accurately grasp the communication status.
[0023]
An object of the present invention is to provide a wireless communication system or the like that avoids the hidden terminal problem in a wireless LAN system and enables efficient and high-throughput operation of a wireless LAN system in view of the above conventional problems.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, a wireless communication system according to the present invention further comprises a mobile communication system including a plurality of mobile terminals performing wireless communication and an access point performing wireless communication with the plurality of mobile terminals. Means for causing a terminal to participate in the wireless communication system, and after the new mobile terminal has joined the wireless communication system, the access point and each of the mobile terminals transmit a control packet, respectively, based on a reception state of the packet. Means for detecting the presence of a hidden terminal on a wireless network in which the mobile terminals cannot communicate with each other, and means for displaying information on the detected hidden terminal.
[0025]
In the wireless communication method of the wireless communication system of the present invention, a wireless communication method of a wireless communication system including a plurality of mobile terminals performing wireless communication, and an access point performing wireless communication with the plurality of mobile terminals, A process in which a new mobile terminal newly joining the wireless communication system performs a connection request / connection permission with the access point; and a first response request packet including an address of the new mobile terminal. A process in which the access point transmits to the mobile terminal, a process in which the new mobile terminal transmits a first response packet in response to the first response request packet, and a process in which mobile terminals other than the new mobile terminal A process of determining whether the first response packet has been received and holding the determination result as a first determination result; A process for sequentially transmitting a second response request packet to mobile terminals other than the new mobile terminal, and after the mobile terminal other than the new mobile terminal receives the second response request packet, A process of transmitting a second response packet including the result of the determination, a process in which the access point receives the second response packet and obtains the first determination result, and And determining whether the response packet has been received, and holding the determination result as a second determination result.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 is a conceptual diagram showing a configuration of a wireless LAN system according to an embodiment of the present invention.
[0028]
In the figure, reference numeral 11 denotes a mobile terminal that performs communication using a wireless transmission path, and is a terminal that has already joined the wireless LAN network. Reference numeral 10 denotes a new mobile terminal that is newly joining the network. An access point 12 controls connection of the mobile terminal and connects the mobile terminal to a wired network. 13 denotes an access point setting personal computer connected to the access point 12, and 14 denotes a wired network.
[0029]
Next, the wireless communication method according to the present embodiment will be described with reference to the flowchart in FIG.
[0030]
It is assumed that there are two mobile terminals participating in the wireless LAN system of the present embodiment, and no hidden terminal problem has occurred between them.
[0031]
<Participation of New Mobile Terminal in Network (Step S11)>
FIGS. 3A and 3B are diagrams illustrating a process of joining a new mobile terminal to a network according to the present embodiment.
[0032]
As shown in FIG. 1A, the new mobile terminal 10 sends out a connection request packet 21 to the access point 12. The connection request packet 21 usually includes information such as the MAC address of the mobile terminal 10 and an ESS-ID (Extended Service Set-ID) for identifying the network. Point 12 performs an authentication process for this connection request.
[0033]
As a result of the authentication, when the new mobile terminal 10 is permitted to join the network, the access point 12 sends a connection permission packet 22 to the new mobile terminal 10 as shown in FIG. As a result, the new mobile terminal 10 newly participates in communication on the network.
[0034]
Regarding the authentication method at this time, it is possible to apply a method generally used for a wireless LAN system such as the IEEE 802.11 standard. In the present embodiment, one authentication request and one authentication permission are used. Although an example in which the processing is completed with a packet has been described, a procedure by exchanging a plurality of packets may be adopted depending on the method of the authentication method or the upper layer protocol.
[0035]
<Hidden terminal detection sequence for new mobile terminal (step S12)>
FIGS. 4A and 4B are diagrams showing a hidden terminal detection sequence for a new mobile terminal.
[0036]
In FIG. 1A, the access point 12 broadcasts a first response request packet 31 to all mobile terminals. Here, the specific field defined in the first response request packet 31 includes an address indicating the new mobile terminal 10 as a mobile terminal to respond to. The new mobile terminal 10 among the mobile terminals that have received the first response request packet 31 recognizes that the response request is addressed to itself, while the other mobile terminals 11a and 11b transmit the first response request packet 31 Only recognizes and stores the fact that the packet has been transmitted from the access point 12 to the new mobile terminal 10, and the other mobile terminals 11a and 11b do not respond to the access point 12 that sent this packet. .
[0037]
The new mobile terminal 10 that has received the first response request packet 31 broadcasts the first response packet 32 to the access point and all other mobile terminals as shown in FIG. 4B. In FIG. 4B, three arrows (32a, 32b, 32c) are given as the first response packet 32, which show the propagation path of the same packet, and are shown on the radio transmission path. Is sent one packet.
[0038]
The first response packet 32 is received by the access point 12 via the path 32c, and is also received by the mobile terminal 11a via the path 32a. On the other hand, it is assumed that the first response packet transmitted to the mobile terminal 11b via the path 32b has a long propagation distance and has not been normally received by the mobile terminal 11b. The path of the packet that has not been received normally is indicated by a broken line as shown in FIG.
[0039]
Here, since the mobile terminal 11a receives both the first response request packet 31 transmitted from the access point 12 and the first response packet 32 transmitted from the new mobile terminal 10, the mobile terminal 11a transmits the first response request packet 31 from the new mobile terminal 10. While knowing that the packet has been successfully received, the mobile terminal 11b receives the first response request packet 31 sent by the access point 12 from the new mobile terminal 10 within a certain period of time despite receiving the first response request packet 31. Since the first response packet 32 cannot be received, it recognizes that the new mobile terminal 10 is a hidden terminal for itself.
[0040]
That is, at the time when this sequence is completed, the first determination result that the new mobile terminal 10 is not a hidden terminal for itself to the mobile terminal 11a, and the new mobile terminal 10 included in the first response request packet Can be held. Also, the mobile terminal 11b can hold the first determination result that the new mobile terminal 10 is a hidden terminal for itself and the MAC address of the new mobile terminal 10 included in the first response request packet. .
[0041]
<Hidden terminal detection sequence regarding other mobile terminals (step S13)>
FIGS. 5A and 5B are diagrams showing hidden terminal detection sequences for other mobile terminals.
[0042]
As shown in FIG. 1A, the access point 12 broadcasts a second response request packet 41 to all the mobile terminals 10, 11a and 11b. Here, the specific field defined in the second response request packet 41 includes, for example, an address indicating the mobile terminal 11a as a mobile terminal to which a response is made.
[0043]
The mobile terminal 11a among the mobile terminals receiving the second response request packet 41 recognizes that it is a response request addressed to itself, while the other mobile terminals 10 and 11b recognize that the second response request packet 41 It merely recognizes and stores the fact that the packet was transmitted from the access point 12 to the mobile terminal 11a, and the other mobile terminals 10 and 11b do not make any response to the access point 12 that sent this packet.
[0044]
The mobile terminal 11a that has received the second response request packet 41 sends the second response packet 42 to the access point 12 and all other mobile terminals 10, 11b, as shown in FIG. Information. In FIG. 5B, three arrows (42a, 42b, 42c) are attached as the second response packet 42, which indicate the propagation path of the same packet, and Is sent one packet. The second response packet 42 is received by the access point 12 via the path 42c, and is simultaneously received by the mobile terminal 10 via the path 42a and further by the mobile terminal 11b via the path 42b.
[0045]
The access point 12 that has received the second response packet 42 analyzes the packet 42 and obtains the first determination result of the mobile terminal 11a included in the packet. Thus, the access point 12 can know the information that the new mobile terminal 10 is not a hidden terminal for the mobile terminal 11a.
[0046]
In addition, since both the mobile terminals 10 and 11b have received both the second response request packet 41 transmitted from the access point 12 and the second response packet 42 transmitted from the mobile terminal 11a, the mobile terminal 11a transmits the packet. Know that the packet was successfully received. Thereby, the mobile terminals 10 and 11b each obtain a second determination result that the mobile terminal 11a is not a hidden terminal when viewed from itself.
[0047]
In the present embodiment, the hidden terminal detection sequence is repeatedly performed for all mobile terminals (step S14).
[0048]
<Hidden terminal detection sequence regarding the last remaining mobile terminal 11b>
FIGS. 6A and 6B are diagrams showing a hidden terminal detection sequence regarding the last remaining mobile terminal 11b.
[0049]
As shown in FIG. 1A, the access point 12 broadcasts a second response request packet 51 to all the mobile terminals 10, 11a and 11b. Here, the specific field defined in the second response request packet 51 includes an address indicating the mobile terminal 11b as the mobile terminal to respond to. The mobile terminal 11b receiving the second response request packet 51 recognizes that the response request is addressed to itself, while the other mobile terminals 10 and 11a transmit the second response request packet 51 from the access point 12 to the mobile terminal 11b. It merely recognizes and stores the fact that the packet has been transmitted to the terminal 11b, and the mobile terminals 10 and 11ab do not make any response to the access point 12 that has transmitted this packet.
[0050]
The mobile terminal 11b that has received the second response request packet 51 broadcasts the second response packet 52 to the access point 12 and all other mobile terminals 10, 11a as shown in FIG. I do. In FIG. 6B, three arrows (52a, 52b, 52c) are attached as the second response packet 52, which indicate the propagation path of the same packet, and Is sent one packet. The second response packet 52 is received by the access point 12 via the route 52c, and is also received by the mobile terminal 11a via the route 52a. On the other hand, it is assumed that the second response packet transmitted to the mobile terminal 10 via the route 32b has a long propagation distance and has not been normally received by the mobile terminal 10.
[0051]
The access point 12 that has received the second response packet 52 analyzes the packet 52 and obtains the first determination result of the mobile terminal 11b included in the packet. Thereby, the access point 12 can know the information that the new mobile terminal 10 is a hidden terminal for the mobile terminal 11b.
[0052]
Further, since the mobile terminal 11a receives both the second response request packet 51 transmitted from the access point 12 and the second response packet 52 transmitted from the mobile terminal 11b, the packet transmitted from the mobile terminal 11b is normally transmitted. On the other hand, the mobile terminal 10 knows that it has been able to receive the second response packet 51 from the mobile terminal 11b within a certain period of time despite receiving the second response request packet 51 transmitted by the access point 12. Since the mobile terminal 11b cannot be received, it recognizes that the mobile terminal 11b is a hidden terminal for itself.
[0053]
At this point, the mobile terminal 10 determines the second determination result that the mobile terminal 11b is a hidden terminal for itself and the MAC address of the terminal 11b, and the mobile terminal 11a determines that the mobile terminal 11a is not a hidden terminal for itself. And the MAC address of the terminal 11b can be recognized.
[0054]
At the stage where all the processes described above are completed, each of the mobile terminals 10, 11a, and 11b has a MAC address of a partner terminal that is a hidden terminal for itself and a MAC of a partner terminal that is not a hidden terminal for itself. While recognizing the address, the access point 12 recognizes the MAC address of the mobile terminal that is hidden from the new mobile terminal 10.
[0055]
<Configuration example of mobile terminal>
FIG. 7 is a diagram illustrating a configuration example of the mobile terminal. Here, the mobile terminal 11a will be described as an example, but the other mobile terminals 10 and 11b may have the same configuration.
[0056]
The mobile terminal 11a is constituted by, for example, a notebook personal computer, and includes a wireless module 65 for performing wireless communication together with a CPU 61, a memory 62, a graphic processor 63, other devices 64, and the like.
[0057]
The wireless module 65 performs communication with a wireless space via an antenna 66. Further, the mobile terminal 11a has a display 67 as a display means. Since the mobile terminal 11a recognizes the MAC address of the mobile terminal that is a hidden terminal for itself by the above-described processing, the mobile terminal 11a can display the MAC address list 68 of the hidden terminal on the display 67.
[0058]
The user can refer to the hidden terminal information shown on the display 67 and change the arrangement of the mobile terminals to an optimal position so that these hidden terminals do not exist.
[0059]
<Example of access point configuration>
FIG. 8 is a diagram illustrating a configuration example of the access point 12 described above.
[0060]
In the figure, the access point 12 includes a CPU 71, a memory 72, an LCD driver 73, an LCD display 74, a wireless module 75, an antenna 76, a wired LAN transceiver 77, and the like, and the wired LAN transceiver 77 is connected to a wired LAN 78. I have.
[0061]
In general, the access point 12 is often housed in a small housing as a network bridge for connecting a wireless LAN and a wired LAN, and as a display means, an LCD display 74 having a relatively small display range is provided. ing. Since the access point 12 recognizes the MAC address of the mobile terminal that is hidden from the new mobile terminal by the processing, the access point 12 can display the MAC address list of the hidden terminal on the LCD display 74. Generally, the LCD display has a drawback such as a small number of display lines. However, it is possible to notify a user of hidden terminal information by a method of sequentially displaying a plurality of MAC addresses.
[0062]
FIG. 9 is a diagram illustrating another configuration example of the access point 12 described above.
[0063]
In the figure, the access point 12 includes a serial port 80 that can be connected to an external personal computer 81, and is configured to be able to communicate with the personal computer 81. Thus, the state of the access point 12 can be set from the personal computer 81, and the internal state of the access point 12 can be displayed on the personal computer 81.
[0064]
The access point 12 has information as to whether the new mobile terminal is a hidden terminal for another mobile terminal, and can display this hidden terminal information on the display of the personal computer 81.
[0065]
As described above, in the present embodiment, when a mobile terminal newly joins the network in the wireless LAN system, the access point 12 and all the mobile terminals are exchanged by exchanging packets between the access point 12 and the mobile terminal. It is possible to detect the MAC address of a mobile terminal that is a hidden terminal. By notifying the user of the hidden terminal information using the display means, the user constructs a network by arranging mobile terminals and access points while taking care not to cause a hidden terminal problem. can do.
[0066]
In the present embodiment, a notebook personal computer is used as a mobile terminal. However, the present invention can be applied to a desktop personal computer and the like. Similarly, the access point 12 has a configuration other than the present embodiment. The present invention is also included in the scope of the present invention as long as it detects a hidden terminal by the processing described in the present invention.
[0067]
In addition, the example of displaying the MAC address on the display was used as a display method of the hidden terminal. However, for example, each terminal device may be displayed using a host name defined by a user, or may be displayed instead of characters. It is also possible to apply such an application that an icon or the like that can specify the device is displayed.
[0068]
【The invention's effect】
As described in detail above, according to the present invention, after a new mobile terminal has joined the wireless communication system, the access point and each mobile terminal transmit a control packet, and based on the packet reception status, Since the presence of hidden terminals on the network is detected and information on the detected hidden terminals is displayed, the user can accurately know the communication status of the network from the displayed information on the hidden terminals, Mobile terminals and access points can be arranged so that terminal problems can be avoided.
[0069]
As a result, a high-throughput wireless communication system can be constructed, and even if the mobile terminal recognizes itself as a hidden terminal, communication becomes possible by considering the arrangement, thereby increasing the use efficiency of the entire wireless communication network and increasing the efficiency. Operation becomes possible.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of a wireless LAN system according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a wireless communication method according to the embodiment.
FIG. 3 is a diagram illustrating a process of joining a new mobile terminal to a network according to the embodiment;
FIG. 4 is a diagram showing a hidden terminal detection sequence for a new mobile terminal.
FIG. 5 is a diagram showing a hidden terminal detection sequence for another mobile terminal.
FIG. 6 is a diagram showing a hidden terminal detection sequence for the last remaining mobile terminal 11b.
FIG. 7 is a diagram illustrating a configuration example of a mobile terminal according to the embodiment.
FIG. 8 is a diagram illustrating a configuration example of an access point according to the embodiment.
FIG. 9 is a diagram illustrating another configuration example of the access point according to the embodiment.
FIG. 10 is a diagram illustrating a state of packet transmission according to a conventional CSMA-CA access method.
FIG. 11 is a diagram showing a conventional hidden terminal problem.
[Explanation of symbols]
10 Mobile terminal
11a, 11b Mobile terminal
12 access points
14 Wired network
21 Connection request packet
22 Connection permission packet
31 First response request packet
32 First response packet
41 Second response request packet
42 Second response packet
51 Second response request packet
52 Second response packet
74 LCD display

Claims (7)

In a wireless communication system including a plurality of mobile terminals performing wireless communication and an access point performing wireless communication with the plurality of mobile terminals,
Means for newly joining a mobile terminal to the wireless communication system,
After the new mobile terminal has joined the wireless communication system, the access point and each mobile terminal transmit control packets, respectively, and based on the reception status of the packet, the mobile terminals cannot communicate with each other. Means for detecting the presence of a hidden terminal on a wireless network,
Means for displaying information on the detected hidden terminal. The wireless communication system according to claim 1, wherein a display unit is connected to the mobile terminal, and the information of the hidden terminal is displayed on the display unit. 3. The wireless communication system according to claim 1, wherein a display unit is connected to the access point, and the information of the hidden terminal is displayed on the display unit. A wireless communication method of a wireless communication system including a plurality of mobile terminals performing wireless communication and an access point performing wireless communication with the plurality of mobile terminals,
A process in which a new mobile terminal newly trying to join the wireless communication system performs a connection request / connection permission with the access point,
A process in which the access point sends a first response request packet including the address of the new mobile terminal to the mobile terminal,
A process in which the new mobile terminal sends out a first response packet to the first response request packet;
A process of determining whether a mobile terminal other than the new mobile terminal has received the first response packet, and holding the determination result as a first determination result,
A process in which the access point sequentially sends a second response request packet to mobile terminals other than the new mobile terminal,
After the mobile terminal other than the new mobile terminal receives the second response request packet, a process of transmitting a second response packet including the first determination result,
A process in which the access point receives the second response packet and obtains the first determination result;
Determining whether or not the mobile terminal has received the second response packet, and storing the determination result as a second determination result. 5. The wireless communication method according to claim 4, wherein a display unit is connected to the mobile terminal, and the display unit displays the first determination result. 6. The wireless communication method according to claim 4, wherein a display unit is connected to the mobile terminal, and the display unit displays the second determination result. 7. The wireless communication method according to claim 4, wherein a display unit is connected to the access point, and the display unit displays the first determination result.

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