KR20060075470A - Method for preventing from intercept by converting the access frequency in the mobile communication system - Google Patents

Abstract

The present invention relates to a method for preventing eavesdropping using access frequency selection in a mobile communication system, and in particular, providing an access frequency selection mode so that a subscriber station can select an access frequency when accessing a base station; Selecting an access frequency according to the access frequency selection mode when the subscriber originates or receives an incoming call by a call from the base station; Performing a call setup procedure with a base station through the access frequency; And determining, by the base station, whether to be duplicated through the access frequency of the subscriber station and limiting service.

Mobile communication, access frequency, standby mode, eavesdropping, call message, frequency selection

Description

How to prevent eavesdropping by selecting access frequency in mobile communication system {METHOD FOR PREVENTING FROM INTERCEPT BY CONVERTING THE ACCESS FREQUENCY IN THE MOBILE COMMUNICATION SYSTEM}

1 is a view showing the structure of a general mobile communication system.

2 is a diagram illustrating a connection frequency selection method in a mobile communication system according to the present invention.

3 is a signal flow diagram illustrating a procedure for selecting an access frequency in a mobile communication system according to the present invention.

4 is a flowchart illustrating a base station access procedure through access frequency selection of a terminal according to an embodiment of the present invention.

5 is a flowchart illustrating a duplicated terminal detection and service restriction procedure in a base station according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: mobile communication system 101, 102, 103: base station

111, 112, 113: mobile terminal 121, 122, 123: cell

131, 132: communication relay line 140: wireless network switch

200: wireless network switch 210: base station controller

220, 230: base station 240: normal subscriber

241: replica subscriber

The present invention relates to a mobile communication system, and more particularly to a method for preventing eavesdropping in a mobile communication system.

To date, communication services have been developed into two categories: mobile communication and wired communication services. Mobile communication is a technology that provides voice and wireless data services using mobile phones. Advanced Mobile Phone Service system (AMPS), Global System for Mobile communication (GSM), and CDMA (Code of Interim Standard-95) of IS-95 series. Division Multiple Access (CDMA) system, cdma2000 1x / Ev-Do (Evolution Data only), Wideband CDMA (WCDMA), and the like. Such technologies are rapidly growing despite the high usage fee due to the feature that the mobile communication terminal can be used to provide voice calls and wireless data services anytime and anywhere.

1 is a view showing the structure of a general mobile communication system. Referring to FIG. 1, the mobile communication system 100 includes a plurality of cell sites 121 to 123, each of which includes one of the base stations 101, 102, or 103.

The base stations 101 to 103 communicate with a plurality of mobile stations (MS) 111 to 114, and the communication method between the base station and the mobile station may be implemented in various ways as described above. For example, it may be implemented by a code division multiple access (hereinafter referred to as "CDMA") scheme. The mobile stations 111-114 are any suitable wireless devices, and typically include cellular radiotelephones, PCS handset devices, personal digital assistants (PDAs), portable computers, and metering devices.

The dotted line in FIG. 1 shows an approximate area of the cells 121 to 123 where the base stations 101 to 103 are located. The cells are shown in an approximately circular form by way of example, and the cells form different inconsistent shapes depending on the cell environment being selected and natural and artificial obstacles.

As is well known in the art, the cells 121-123 are composed of a plurality of sectors (not shown), and each sector can be described by a directional antenna coupled to the base station. The implementation of Figure 1 shows that there is a base station in the center of the cell. Modified implementations place the directional antennas in the corners of the sectors.

Meanwhile, the base stations 101 to 103 may include one base station controller (BSC) and one or more base station subsystems (BTSs). Base station controllers (BSCs) and base station subsystems (BTSs) are well known to those skilled in the art. A base station controller is a device for managing wireless communication resources including the base stations for specific cells in a wireless communication network. The device may include an air conditioner, a heater, a power supply, a telephone line connection and an RF transmitter / receiver.

Each of the base stations 101 to 103 transmits voice and data signals between each of the base stations and the public switched telephone network (PSTN) while the first communication relay line 131, the switchboard (MSC) 140, and the second communication relay line ( 132). In addition, the first communication relay line 131 is a voice between the MSC 140 and BSs 101 to 103 and the second communication relay line and the MSC 140 and the Internet or PSTN through the first communication relay line. It provides a connection path for transmitting control signals between the MSC 140 and the BSs 101-103 used to establish a connection via data circuits.

The relay lines 131, 132 consist of one or more suitable connection means, including T1, optical link, network packet backbone connection or some other type of data connection. Those skilled in the art will appreciate that the connections to the transmission lines 131 and 132 are for transmission of analog voice band signals, digital channels for transmission of voice signals transmitted in Pulse code modulated (PCM) format, Internet protocol (IP) Will be understood as a digital pathway for transmission of voice signals in A) format, a digital pathway for transmission of voice signals in Asynchronous Transfer Mode (ATM) format, or a transmission pathway by another suitable connection transmission protocol.

On the other hand, the CDMA mobile communication system has the following two characteristics.

First, terminals having the same Mobile Identification Number (hereinafter referred to as 'MIN') should tune to the same frequency. More specifically, in the CDMA mobile communication system, the base station always broadcasts a list of serviceable frequencies in a cell area, and the mobile terminal has its subscriber number for such service frequency list broadcasted by the base station. The hash operation of the algorithm determines the tuning frequency and sets it to the standby mode frequency. Therefore, two subscribers having the same MIN always have the same frequency as the standby mode frequency.

Second, all the forward data is transmitted using a common channel before the call path is formed. When a mobile terminal connects to a base station to set a call, or a base station calls a mobile terminal to set up a call with a mobile terminal, when setting up a call between a mobile subscriber and a base station, Among the call control messages, all forward messages transmitted from the base station to the mobile terminal are transmitted through the paging channel, which is a common channel, and the messages are distinguished by the mobile terminal identification number. Therefore, a plurality of terminals having the same identification information can receive the same forward control message.

Therefore, in the above-described general CDMA mobile communication system, a plurality of terminals having the same terminal identification information as the MIN and an electronic serial number (hereinafter, referred to as 'ESN') in the same cell area exist in the same cell region. There is a problem that can not be identified. For this reason, when using a duplicate terminal injecting identification information of the normal terminal, there is a problem that it is possible to tap the call of the normal terminal.

On the other hand, the authentication procedure is provided as a function to prevent this, but also the authentication procedure only determines the legitimacy of the terminal connected to establish a call, so that the base station does not attempt to access the base station and the base station does not attempt to access the base station. In the case of processing only the information transmitted by the network, there is a problem that detection and eavesdropping of duplication cannot be detected.

An object of the present invention is to allow a subscriber to select a frequency other than the standby mode when accessing a base station in a mobile communication system using multiple frequencies, thereby preventing eavesdropping due to duplicated terminals. An anti-tapping method using frequency selection is provided.

In addition, an object of the present invention is to provide a duplicated terminal by allowing a base station to recognize this as a duplicated terminal and temporarily limit the service in the corresponding base station area for a terminal requesting simultaneous access through different frequencies in a mobile communication system using multiple frequencies. The present invention provides a method for preventing eavesdropping using access frequency selection in a mobile communication system for preventing eavesdropping caused by eavesdropping.

A method according to the present invention for achieving the above object comprises the steps of providing an access frequency selection mode so that the subscriber station can select the access frequency when accessing the base station; Selecting an access frequency according to the access frequency selection mode when a subscriber originates or an incoming response by a call from a base station; Performing a call setup procedure with a base station through the access frequency; And determining, by the base station, whether to be duplicated through the access frequency of the subscriber station and limiting service.

A first method for achieving the above object is characterized in that it comprises the step of setting the access frequency selection mode by the subscriber using a key button or a combination of buttons in the subscriber terminal.

According to a second method of achieving the above object, when the subscriber sets the access frequency selection mode, the access frequency is randomly selected from a list of other service frequencies of the base station instead of the standby mode frequency to which the subscriber station is tuning. Characterized in that it comprises a.

A third method for achieving the above object comprises the steps of determining whether the base station to replicate using the access frequency obtained the signal of the subscriber station; Transmitting the eavesdropping risk warning and the terminal lock command to the subscriber station determined as the duplicated terminal; And limiting a base station access request generated by the duplicated terminal for a predetermined time.

The present invention, in the standby mode to access the access frequency that the terminal accesses to the base station for call establishment in order to block eavesdropping using a duplicated terminal in a conventional mobile communication system, in particular, a code division multiple access method mobile communication system providing multiple frequencies. The present invention proposes a method in which a duplicated terminal monitoring the standby frequency does not recognize the access of a base station to a normal terminal by arbitrarily selecting and accessing a frequency list from other frequencies.

The method according to the present invention is a call control which may be caused when a mobile terminal having the same mobile subscriber identification number (i.e., a MIN) always tunes to the same frequency in the standby mode, i.e., a call setup may occur when performing the call setup at the same frequency. Information leakage can be prevented. In addition, by selecting randomly from the remaining frequency list except the standby mode frequency in the access frequency selection process, it is possible to bypass the tracking using the duplicated terminal.

Meanwhile, when the same terminal attempts to access the base station at the same time through different access frequencies by the method according to the present invention, the base station recognizes it as a duplicated terminal and stops the service for a certain time for the identification number of the duplicated terminal. By doing so, the subscriber's information is not eavesdropped.

That is, the present invention provides a terminal that provides a method for allowing a subscriber to access a base station using a frequency other than the standby mode frequency, a duplicate terminal that duplicates the identification number of the terminal, and a plurality of terminals having the same identification information. When accessing the base station through different access frequencies at the same time, it is determined that the terminal is a duplicated terminal, so that the service is suspended for this terminal and the duplicated terminal is alerted to the danger of copying, and thus the base station provides a method of informing that the service has been stopped. do.

Hereinafter, a detailed description of a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, detailed descriptions of well-known functions or configurations will be omitted when it is determined that the detailed descriptions of the known functions or configurations may unnecessarily obscure the subject matter of the present invention.

First, a concept according to the present invention in a mobile communication system will be described with reference to FIG. 2, and a procedure of performing the method according to the present invention will be described with reference to FIGS. 3 to 5.

2 is a diagram illustrating a method for selecting a connection frequency in a mobile communication system according to the present invention.

Referring to FIG. 2, in the mobile communication system, a plurality of base station controllers 210a to 210n are connected to one wireless network switch 200 as described above, and a plurality of base stations are connected to the one base station controller 210. The fields 220a to 220n may be connected. In this case, the one base station 220a forms one cell and performs communication through a wireless channel with a plurality of mobile terminals 240 and 241 belonging to the cell.

Meanwhile, as described above in the related art, when two terminals 240 and 241 belonging to the same base station 220a have the same MIN and the same ESN, the base station cannot identify the two terminals. Therefore, when using the duplicate terminal 241 injecting identification information of the normal terminal 240, it is possible to tap the call of the normal terminal.

Therefore, in the present invention, when the normal terminal 240 accesses the base station 220a to set up a call, the access frequency is selected from other frequency lists instead of frequencies in the standby mode. Therefore, even if the frequency of the standby mode is the same as that of the normal terminal 240, the duplicated terminal 241 in the same base station 220a is different from the frequency of the normal terminal 240, so that eavesdropping is impossible. do. In addition, at this time, the base station 220a can distinguish the duplicated terminal 241 using a different access frequency from that of the normal terminal 240.

On the other hand, the change of the access frequency of the normal terminal 240 can be implemented to be set according to the user's selection of the terminal 240. Therefore, when the user of the normal terminal 240 wants to make an important call requiring security, it is possible to prevent eavesdropping by using the function of changing the access frequency according to the present invention. In addition, even when the user of the normal terminal 240 detects the possibility of eavesdropping, the copy terminal 241 can be tracked by the access frequency changing function according to the present invention.

Hereinafter, the procedure for changing the access frequency according to the present invention will be described in detail with reference to FIGS. 3 to 5.

3 is a signal flow diagram illustrating a procedure for selecting an access frequency in a mobile communication system according to the present invention.

Referring to FIG. 3, the normal subscriber 240 in the same base station 220a selects the access frequency as a frequency different from the standby frequency in order to prevent eavesdropping of the duplicate subscriber 241.

For example, it is assumed that the base station 220a has three frequencies A, B, and C as serviceable frequencies. At this time, the base station 220a periodically broadcasts (S301, S302) through a paging channel, which is a common channel, with A, B, and C as service frequency lists.

The normal subscriber station 240 performs a hash operation on its list of service frequencies broadcast by the base station using its subscriber number, and as a result tunes to the second service frequency B obtained from the frequencies of A, B, and C. In operation S303, the standby mode is maintained at the frequency B.

In this case, the duplicated subscriber station 241 also has the same subscriber number as the normal subscriber station 240, so that the duplicated subscriber station 241 synchronizes with the same service frequency B as the normal subscriber station 240 to maintain the standby mode state (S304).

On the other hand, when a call comes to the subscriber stations (240, 241), the base station 220a broadcasts a call message for the subscriber number of the normal subscriber. The call message is simultaneously received (S305, S306) at the normal subscriber station and the duplicated terminal having the same calling party number.

The normal subscriber station 240 checks whether the access frequency selection mode is set according to the present invention and, if the access frequency selection mode is set, performs a hash operation on the subscriber number in the service frequency list of the base station. The access frequency is determined by randomly selecting one of the remaining frequencies (eg, A and C frequencies) except for the obtained B frequency. On the other hand, when the access frequency mode is not set in the normal subscriber station 240, it connects to the base station using the standby mode frequency as the access frequency as in the related art.

In FIG. 3, it is assumed that the normal subscriber station is set to the access frequency selection mode, so that A is determined as a randomly selected access frequency among the A and C frequencies (S307). At this time, the normal subscriber station 240 transmits a response message for the base station call at the A frequency (S308). On the other hand, the replica terminal 241 transmits a response message to the base station call using the standby mode frequency (that is, frequency B) as the access frequency (S309).

On the other hand, the base station 220a determines whether the access frequency is the same for the two call response messages received at the same time, if the access frequency is the same process as a duplicate message and if the access frequency is different (S310) to the standby frequency The terminal 241, which has transmitted the call response message, is treated as a duplicate terminal to perform the procedure accordingly.

At this time, when the duplicated terminal 241 is detected, the base station 220a terminates the normal call setup procedure for the normal subscriber terminal 240 and the duplicated terminal 241, and the normal subscriber 240 or the normal subscriber 240. And the duplicate subscriber 241, the risk of eavesdropping and a certain time due to the access blocking notification (S311, S312) and manages it. In addition, the base station 220a blocks the call service of the normal subscriber station 240 and the replica terminal 2410 during the connection disconnection time (S313).

Hereinafter, a procedure performed by a terminal and a base station according to the present invention will be described with reference to FIGS. 4 and 5. First, the access frequency selection procedure in the terminal will be described with reference to FIG. 4, and the duplicated terminal detection and service restriction procedure in the base station will be described with reference to FIG. 5.

4 is a flowchart illustrating a base station access procedure by selecting an access frequency of a terminal according to an embodiment of the present invention.

Referring to FIG. 4, when accessing a base station, a normal terminal can set an access frequency selection mode according to an embodiment of the present invention for security.

First, when power is applied to the normal terminal (S401), generally proceeds to the standby mode (S402). At this time, if the state is not switched to the connected mode, it is continuously set to the standby mode. On the other hand, when the state is switched to the connected mode (S403) to make a call or a response (S404) to the call from the base station, the access frequency is changed depending on whether the connection mode is set according to the present invention.

That is, when the access frequency selection mode is set in the normal terminal (S405), the access frequency is selected at a frequency other than the frequency in the standby mode (S406) and connected to the base station (S407). On the other hand, when the access frequency selection mode is not set in the normal terminal, the access point is connected to the base station using the frequency in the standby mode as the access frequency as in the prior art (S407).

5 is a flowchart illustrating a duplicated terminal detection and service restriction procedure in a base station according to an embodiment of the present invention.

Referring to FIG. 5, the base station performs a call setup procedure for the access request of the terminal in the reception standby mode (S501). At this time, if the service restriction for the terminal is set (S503), the eavesdropping warning message is transmitted to the corresponding terminal (S506), and the terminal lock command is transmitted (S507).

On the other hand, if the service restriction for the terminal is not set, the terminal with the same MIN number is already connected, it is determined whether the access frequency is the same. As a result of the determination, when the access frequency is the same frequency, it transmits a message reception response (S508) and performs a normal call setup procedure (S509).

On the other hand, if the access frequency is not the same frequency as a result of the determination, the terminal is registered as a service restriction terminal, and the service time limit is set (S505). Then, the eavesdropping warning message is transmitted to the corresponding terminal (S506), and the terminal lock command is transmitted (S507).

On the other hand, in the embodiment of the present invention has been described with respect to specific embodiments, of course, various modifications are possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the appended claims, but also by those equivalent to the claims.

According to the present invention, it is possible to prevent the leakage of the subscriber's privacy and personal information by acquiring the identification information of the normal terminal and protecting the subscriber from the call eavesdropping of the duplicated terminal or precise eavesdropping equipment. In addition, when detecting the duplication, by limiting the call for a predetermined time by limiting the service for the duplicated terminal to the base station for which the duplication is detected, it is possible to minimize the service limitation due to the duplicated terminal.

Claims (11)

Providing an access frequency selection mode to allow a subscriber station to select an access frequency when accessing a base station; Selecting a access frequency according to the access frequency selection mode when a call connection situation occurs between the subscriber station and the base station; Performing a call setup procedure with a base station through the access frequency; And And determining, by the base station, whether to be duplicated through the access frequency of the subscriber station, and limiting a service. The method of claim 1, wherein the call connection situation, In the mobile communication system characterized in that the subscriber station to the base station to the eavesdropping method using the access frequency selection. The method of claim 1, wherein the call connection situation, In the mobile communication system characterized in that the subscriber station is an incoming call response to the call to the base station. The method of claim 1, wherein the method is And setting the access frequency selection mode by the subscriber by using a key button or a combination of buttons in the subscriber terminal. The method of claim 1, wherein the selecting method of the other frequency, When the subscriber sets the access frequency selection mode, accessing a mobile communication system comprising randomly selecting an access frequency from a list of other service frequencies of the base station instead of a standby mode frequency to which the subscriber station is tuning. Eavesdropping prevention method using frequency selection. The method of claim 1, wherein the step of determining whether or not to replicate, Determining, by the base station, whether to replicate by using an access frequency obtained with a signal of a subscriber station; Transmitting the eavesdropping risk warning and the terminal lock command to the subscriber station determined as the duplicated terminal; And And limiting a base station access request generated by the duplicated terminal for a predetermined time. The method of claim 1, wherein the method is Receiving, by the subscriber station, a list of service frequencies broadcast by the base station; Hashing the service frequency list by the subscriber station using its subscriber number; And And tuning to one service frequency obtained from the received service frequency list as a result of the operation. The method of claim 1, further comprising: access frequency selection in a mobile communication system. The method of claim 1, wherein the base station receives two or more response messages, Determining whether access frequencies match for the two received call response messages; And And processing the message as a duplicate message if the access frequency is the same as the result of the determination. The method of claim 1, wherein the base station receives two or more response messages, Determining whether access frequencies match for the two received call response messages; And And detecting the duplicated terminal by processing the terminal which has transmitted the call response message at the standby frequency as a duplicated terminal when the determination result indicates that the connected frequency is different. Prevention method. The method of claim 9, wherein after detecting a duplicate terminal of the base station, The base station notifies the normal terminal of the risk of eavesdropping; characterized in that it further comprises a wiretap prevention method using the access frequency selection in a mobile communication system. The method of claim 9, wherein after detecting a duplicate terminal of the base station, The base station further comprises the step of blocking a call service to the duplicated terminal; in the mobile communication system characterized in that the eavesdrop prevention method using the access frequency selection.

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