JP2007274252A - Terminal, program and access point discovery method for communicating with stealth access point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a terminal and the like preventing transmission of a wasteful probe request from the terminal for detecting a stealth access point. <P>SOLUTION: The terminal can communicate with a normal access point for reporting a network discriminator, and can communicate with a stealth access point which does not report the network discriminator. The terminal comprises an access point information accumulator 103 which accumulates the access point information indicating whether a normal access point or stealth access point for each access point, a beacon signal detector 101 which listens to beacon signals for detection, a probe request transmitter 105 for transmitting a probe request, and an access point finding control unit 102 which controls so that the normal access point detects beacon signals by the beacon signal detector 101 while the stealth access point transmits the probe request through the probe request transmitter 105. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a terminal that communicates with a stealth access point, a program, and an access point discovery method.

  The wireless LAN has a MAC (Medium Access Control) layer technology for controlling packet transmission between an access point and a terminal. The MAC frame exchanged between the wireless stations by the MAC layer is defined by, for example, the IEEE 802.11 standard.

  FIG. 1 is a system configuration diagram showing a sequence between a terminal and an access point in the prior art.

  In the case of the IEEE802.11 infrastructure mode, the access point periodically sends a beacon signal including an ESSID (Extended Service Set Identifier), which is a network identifier, to peripheral terminals (approximately every 100 ms). Send. The terminal that has received the beacon signal can connect to the access point using the ESSID. In this way, the terminal can easily find an access point (network identifier) existing in the vicinity. This, on the other hand, means that all terminals can discover their network identifier.

  In recent years, stealth access points are increasingly used from the viewpoint of ensuring security. A “stealth access point” refers to an access point that does not broadcast a network identifier such as an ESSID. In order not to notify the ESSID, there are a case where the beacon signal is stopped and a case where a beacon signal not including the ESSID is notified. When a stealth access point is used, the presence of a network can be prevented from being easily detected in the surroundings. In order to connect to a stealth access point, the terminal needs to know the ESSID of the stealth access point.

  In order to discover a stealth access point, the terminal transmits a probe request including the ESSID of the stealth access point. When trying to find all access points present in the vicinity, the terminal includes ESSID = any in the probe request.

  The stealth access point determines whether or not the ESSID included in the received probe request matches its own ESSID. If they match, the stealth access point returns a probe response including the ESSID to the terminal. When a probe request with ESSID = any is received, the stealth access point does not return a probe response to the terminal.

  Further, as a conventional technique, there is a technique in which a terminal appropriately changes an access point to be connected according to an application (see, for example, Non-Patent Document 1). According to this technique, a specific base station broadcasts access point information corresponding to the position range. The terminal that has received this access point information can determine the access point to search according to the current position.

WenhuiZhang, Jurgen Juhnert, Klaus Dolzer, `` Design and Evaluation of A Handover DecisionStrategy for 4th Generation Mobile Networks '', IEEE VTC, April 2003, Jeju, Korea

  According to the prior art, the terminal does not recognize whether the access point is a normal access point or a stealth access point. Therefore, the terminal needs to listen to the beacon signal from the access point (network identifier) and periodically notify the probe request to all the access points registered in advance.

  According to the prior art, the terminal is not set for the presence or absence of stealth of the access point. In other words, even when the terminal is present at a position where it cannot communicate with the stealth access point, the terminal periodically notifies probe requests to all previously registered access points and also changes the reception frequency. Such an operation not only wastes radio resources but also leads to waste of power consumption in the terminal. In the future, from the viewpoint of security, when a large number of stealth access points are arranged, many stealth access points must be found, and the number of transmitted packets increases.

  Therefore, an object of the present invention is to provide a terminal, a program, and an access point discovery method that can prevent a terminal from transmitting a useless probe request in order to detect a stealth access point.

According to the present invention, a normal access point that broadcasts a network identifier and a terminal that can communicate with a stealth access point that does not broadcast a network identifier,
For each access point, access point information storage means for storing access point information indicating whether it is a normal access point or a stealth access point;
Beacon signal detecting means for listening and detecting a beacon signal including a network identifier;
Probe request transmitting means for transmitting a probe request including a network identifier;
It has an access point discovery control means for controlling a beacon signal to be detected by a beacon signal detection means for a normal access point, and to transmit a probe request by a probe request transmission means for a stealth access point. And

According to another embodiment of the terminal of the present invention,
It further has a positioning means for measuring the current position,
The access point information storage means includes location range information in the access point information for each access point,
The access point discovery control means preferably controls the probe request transmission means to transmit the probe request only to the stealth access point whose current position of the terminal is included in the position range information.

According to another embodiment of the terminal of the present invention,
It is also preferable that the probe request transmission means continuously transmits a plurality of probe requests at a time interval shorter than a normal probe request transmission interval.

According to the present invention, there is provided a system including the terminal described above and a broadcasting station apparatus capable of transmitting data to the terminal,
The broadcasting station apparatus broadcasts access point information indicating whether it is a normal access point or a stealth access point for each access point,
The terminal stores the received access point information in an access point information storage unit.

According to the present invention, a program for causing a computer installed in a terminal capable of communicating with a normal access point for informing a network identifier and a stealth access point for not informing a network identifier,
For each access point, access point information storage means for storing access point information indicating whether it is a normal access point or a stealth access point;
Beacon signal detecting means for listening and detecting a beacon signal including a network identifier;
Probe request transmitting means for transmitting a probe request including a network identifier;
For normal access points, beacon signal detection means detects the beacon signal, and for stealth access points, the probe request transmission means controls the computer to function as an access point discovery control means. It is characterized by.

According to another embodiment of the terminal program of the present invention,
Further function as a positioning means to measure the current position,
The access point information storage means includes location range information in the access point information for each access point,
The access point discovery control means preferably causes the computer to function so as to control the probe request transmission means to transmit the probe request only to the stealth access point whose current position of the terminal is included in the position range information. .

According to another embodiment of the terminal program of the present invention,
The probe request transmission means preferably causes the computer to function so as to continuously transmit a plurality of probe requests at a time interval shorter than a normal probe request transmission interval.

According to the present invention, an access point discovery method in a terminal capable of communicating with a normal access point that broadcasts a network identifier and a stealth access point that does not broadcast a network identifier,
Each access point has an access point information storage unit that stores access point information indicating whether it is a normal access point or a stealth access point,
For normal access points, listen and detect beacon signals including network identifiers,
A probe request including a network identifier is transmitted to the stealth access point.

According to another embodiment of the access point discovery method of the present invention,
The access point information storage unit includes location range information in the access point information for each access point,
It is also preferable that the probe request is transmitted by the probe request transmitting means only to the stealth access point whose current position of the terminal is included in the position range information.

  According to another embodiment of the access point discovery method of the present invention, it is also preferable that the probe request is continuously transmitted with a plurality of probe requests at a time interval shorter than a normal probe request transmission interval.

  According to the terminal, program, and access point discovery method of the present invention, probe requests are not transmitted to all registered ESSIDs when discovering a stealth access point. Accordingly, the terminal can greatly reduce the number of probe request transmissions for discovering the stealth access point, and can reduce both the wireless resources of the network and the power consumption of the terminal.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a system configuration diagram according to the present invention.

  According to FIG. 2, the terminal 1 exists at a position where it can communicate with the stealth access point 2. The terminal 1 can also receive peripheral access point information broadcast from the broadcast station (or cellular base station) 3.

  The terminal 1 includes a beacon signal detection unit 101, an access point discovery control unit 102, an access point information storage unit 103, a positioning unit 104, a probe request transmission unit 105, an access point connection processing unit 106, a peripheral access point And an information receiving unit 107. These functional units can also be realized by a program executed by a computer mounted on the terminal 1.

The access point information storage unit 103 stores, for each access point, access point information indicating whether it is a normal access point or a stealth access point. The access point information storage unit 103 stores, for example, a table as shown in Table 1 below.

  The ESSID means an access point identifier, that is, a “network identifier”. For each ESSID, “wireless system type”, “frequency”, and “WEP (Wired Equivalent Privacy)” are registered. According to the present invention, each ESSID further includes “stealth presence / absence”, “priority”, and “position range information”.

  “Stealth presence / absence” indicates whether the access point of the ESSID is a normal stealth access point or a stealth access point. The “priority” indicates the priority order to which the terminal should be connected, and the search is performed in order from the ESSID having the highest priority. “Location range information” represents a location range in which communication with the access point of the ESSID is possible. The position range information is represented by, for example, a latitude / longitude serving as a center point and a radius thereof.

  The beacon signal detection unit 101 listens to and detects beacon signals transmitted from normal access points. When receiving the beacon signal, the beacon signal detection unit 101 notifies the access point discovery control unit 102 to that effect.

  The beacon signal is composed of a MAC frame. The MAC frame includes “frame control”, “DurationID”, “destination address”, “source address”, “BSSID (Basic Service Set IDentifier)”, “sequence control”, “frame body”, and “FCS”. The beacon signal is specified by “type” and “subtype” of “frame control”. “Type = 00” means a management frame, and “subtype = 1000” means a beacon signal. “BSSID” represents the MAC address of the access point.

The message body of the beacon signal includes the following “beacon basic information”.
・ Timestamp: Timer TSFTIMER value (μs unit)
・ Beacon Interval: Beacon period (1024μs unit)
-Capability Information: Presence of centralized polling control (PCF) or encryption-SSID (Service Set ID): ESSID or IBSSID
-Supported Rate: List of wireless transmission rates supported by the access point

  The probe request transmission unit 105 transmits a probe request to the stealth access point 2. The probe request includes the ESSID to be discovered. Here, it is also preferable that the probe request transmission unit 105 continuously transmits a plurality of probe requests at a time interval shorter than a normal probe request transmission interval. For example, a probe request is transmitted three times in succession, and then a probe response is waited for a predetermined time. If a probe response is not received, the next access point is found without sending a further probe request. Thereby, the time for discovering a stealth access point can be shortened.

  The access point discovery control unit 102 switches the means for finding the access point based on the “presence / absence of stealth” of the access point information stored in the access point information storage unit 103. A beacon signal is detected by a beacon signal detection unit 101 for a normal access point. On the other hand, the probe request transmission unit 105 controls the stealth access point to transmit a probe request. According to the present invention, a terminal transmits a probe request only to a stealth access point and does not transmit a probe request to a normal access point. Such an operation can reduce power consumption for the terminal to find the access point.

  Here, the access point discovery control unit 102 controls the probe request transmission unit 105 to transmit a probe request only to a stealth access point whose current position of the terminal is included in the position range information. The current position of the terminal is acquired from the positioning unit 104. Further, the location range information of the stealth access point is acquired from the access point information storage unit 103. And the access point discovery control part 102 determines whether the present position of the said terminal exists in the position range of the stealth access point. If it exists, the probe request transmission unit 105 is instructed to transmit a probe request. Thereby, the terminal 1 does not transmit a probe request to a stealth access point whose current position is not included in the position range information. The access point discovery control unit 102 searches for access points in descending order of priority of the access point information.

  The positioning unit 104 measures the current position. For example, latitude and longitude information is acquired by a positioning function such as GPS (Global Positioning System).

  The access point connection processing unit 106 processes the connection sequence for the access point (network identifier) discovered by the access point discovery control unit 102. When a beacon signal or a probe response is received, an association request is transmitted to the access point 2 to process the connection sequence.

  The peripheral access point information receiving unit 107 receives peripheral access point information from the broadcast station 3. The peripheral access point information is stored in the access point information storage unit 103. Accordingly, the terminal can recognize a nearby access point at the current position.

  According to FIG. 2, the stealth access point 2 includes a probe request reception unit 201, an ESSID determination unit 202, a probe response transmission unit 203, and a terminal connection processing unit 204.

  The probe request receiving unit 201 receives a probe request from the terminal 1. The ESSID included in the received probe request is notified to the ESSID determination unit 202.

  The ESSID determination unit 202 determines whether or not the ESSID notified from the probe request reception unit 201 matches the ESSID of the stealth access point itself. If they match, this is notified to the probe response transmission unit 203.

  The probe response transmission unit 203 transmits a probe response to the terminal 1 when receiving a notification that the ESSID matches from the ESSID determination unit 202. The probe response includes the same information elements as the beacon signal.

  The terminal connection processing unit 204 processes a connection sequence with the terminal 1. An association request is received from the terminal 1 and the connection sequence is processed.

  FIG. 3 is a sequence diagram in the present invention.

(S301) Broadcast station (or cellular base station) 3 broadcasts peripheral access point information of neighboring access points. The peripheral access point information particularly includes “stealth presence / absence”, “location range information”, and “priority”.
(S302) The terminal 1 accumulates peripheral access point information received from the broadcast station 3.
(S303) The terminal 1 searches for an access point that can be connected at the current position based on the “position range information” of the access point information.
(S304) The terminal 1 determines the “priority” order for the searched access points.

(S305) When a normal access point is found, the frequency used by the normal access point is set.
(S306) Then, the terminal 1 listens to the beacon signal normally transmitted from the access point 2 for a certain period of time.
(S307) The normal access point 2 periodically transmits a beacon signal including an ESSID. The terminal 1 receives the beacon signal.
(S308) Upon receiving the beacon signal, the terminal 1 processes the connection sequence for the normal access point 2.

(S309) When a stealth access point is found, it is set to the frequency used by the stealth access point, and the ESSID and WEP are specified.
(S310) The terminal 1 transmits a probe request including the ESSID to the stealth access point 2.
(S311) The stealth access point 2 determines whether or not the ESSID included in the probe request matches its own ESSID.
(S312) When they match, the stealth access point 2 returns a probe response to the terminal 1.
(S313) Upon receiving the probe response, the terminal 1 processes the connection sequence for the stealth access point 2.

  As described above, according to the terminal, program, and access point discovery method of the present invention, probe requests are not transmitted to all registered ESSIDs when discovering a stealth access point. Accordingly, the terminal can greatly reduce the number of probe request transmissions for discovering the stealth access point, and can reduce both the wireless resources of the network and the power consumption of the terminal.

  According to the various embodiments of the present invention described above, those skilled in the art can easily make various changes, modifications and omissions within the scope of the technical idea and the viewpoint of the present invention. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

It is a system block diagram showing the sequence between the terminal and access point in a prior art. It is a system configuration diagram in the present invention. It is a sequence diagram in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Terminal 101 Beacon signal detection part 102 Access point discovery control part 103 Access point information storage part 104 Positioning part 105 Probe request transmission part 106 Access point connection processing part 107 Peripheral access point information reception part 2 Access point 201 Probe request reception part 202 ESSID Determination unit 203 Probe response transmission unit 204 Terminal connection processing unit 3 Broadcast station, cellular base station

Claims (10)

A normal access point that broadcasts a network identifier and a terminal that can communicate with a stealth access point that does not broadcast a network identifier,
For each access point, access point information storage means for storing access point information indicating whether it is a normal access point or a stealth access point;
Beacon signal detecting means for listening and detecting a beacon signal including a network identifier;
Probe request transmitting means for transmitting a probe request including a network identifier;
An access point discovery control means for controlling the normal access point to detect a beacon signal by the beacon signal detection means and to transmit a probe request to the stealth access point by the probe request transmission means; A terminal characterized by having. It further has a positioning means for measuring the current position,
The access point information storage means includes location range information in access point information for each access point,
The access point discovery control unit controls the probe request transmission unit to transmit a probe request only to a stealth access point whose current position of the terminal is included in the position range information. The terminal according to claim 1.   The terminal according to claim 1, wherein the probe request transmission unit continuously transmits a plurality of probe requests at a time interval shorter than a normal probe request transmission interval. A system comprising the terminal according to any one of claims 1 to 3 and a broadcasting station device capable of transmitting data to the terminal,
The broadcast station apparatus broadcasts access point information indicating whether it is a normal access point or a stealth access point for each access point,
The terminal stores the received access point information in the access point information storage means. A program that causes a computer installed in a terminal that can communicate with a normal access point that broadcasts a network identifier and a stealth access point that does not broadcast a network identifier,
For each access point, access point information storage means for storing access point information indicating whether it is a normal access point or a stealth access point;
Beacon signal detecting means for listening and detecting a beacon signal including a network identifier;
Probe request transmitting means for transmitting a probe request including a network identifier;
A computer as an access point discovery control unit that controls the beacon signal to be detected by the beacon signal detection unit for the normal access point and the probe request transmission unit to transmit a probe request to the stealth access point. A program for a terminal, characterized by causing the function to function. Further function as a positioning means to measure the current position,
The access point information storage means includes location range information in access point information for each access point,
The access point discovery control means causes the computer to function so as to control the probe request transmission means to transmit a probe request only to a stealth access point whose current position of the terminal is included in the position range information. The terminal program according to claim 5.   The said probe request transmission means makes a computer function so that a several probe request may be continuously transmitted in the time interval shorter than the transmission interval of a normal probe request. A program for terminals. An access point discovery method in a terminal capable of communicating with a normal access point that broadcasts a network identifier and a stealth access point that does not broadcast a network identifier,
Each access point has an access point information storage unit that stores access point information indicating whether it is a normal access point or a stealth access point,
For the normal access point, a beacon signal including a network identifier is detected by listening,
An access point discovery method, comprising: transmitting a probe request including a network identifier to the stealth access point. The access point information storage unit includes location range information in access point information for each access point,
9. The access point discovery method according to claim 8, wherein a probe request is transmitted by the probe request transmission unit only to a stealth access point whose current position of the terminal is included in the position range information. The access point discovery method according to claim 8 or 9, wherein the probe request is continuously transmitted with a plurality of probe requests at a time interval shorter than a normal probe request transmission interval.

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