JP3136879B2 - Wireless communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system comprising a radio base station and a radio mobile station, and in particular, an illegal access from a radio mobile station causes improper use of CPU resources of the radio base station. The present invention relates to a wireless communication system capable of preventing the problem.

[0002]

2. Description of the Related Art First, a conventional operation for transmitting a signal from a radio mobile station to a radio base station will be described. FIG. 9 is a diagram illustrating an example of a transmission sequence when a wireless mobile station transmits to a wireless base station. In the figure, reference numeral 91 denotes an upstream transmission signal from a wireless mobile station to a wireless base station, which is a signal for requesting the establishment of a wireless link. FIG. 10 shows an example of this uplink transmission signal. In FIG. 10, 101 is a preamble for synchronizing in the wireless transceiver, 102 is an uplink synchronization word, 103 is a broadcast channel, an individual control channel,
This is a channel type indicating a channel type such as an incoming channel, and is displayed as an individual control channel in an outgoing signal. 10
4 is the base station ID of the destination of the uplink signal, 105 is the mobile station ID of the wireless mobile station transmitting the transmission signal, and 106 is the message type, in which case "transmission" is displayed. 107
Is the transmission signal data, and 108 is the CR for detecting bit errors.
This is a C (Cyclic Redundancy Check) code.

[0003] Reference numeral 92 denotes a downlink channel designation signal from a radio base station, which is a signal for designating a channel of a radio link. FIG. 11 shows an example of the downlink channel designation signal. In FIG. 11, 111 is a preamble for synchronizing in a wireless transceiver, 112 is a downlink synchronization word, 113 is a channel type indicating a channel type such as a broadcast channel, an individual control channel, an incoming channel, and the like. Displays as channel. 11
4 is a base station ID of a wireless base station transmitting the downlink signal,
Reference numeral 115 denotes the mobile station ID of the wireless mobile station that is the destination of the downlink signal, and reference numeral 116 denotes a message type, in which case "channel designation" is displayed. Reference numeral 117 denotes data of a channel designation signal, and reference numeral 118 denotes a CRC. Reference numeral 93 denotes a call setting signal for performing end-to-end call setting using a wireless link established by exchanging an upstream transmission signal 91 and a downstream signal 92; 94, a call setting acceptance signal; and 95, authentication of a wireless mobile station. , 96 is an authentication response signal responding to the 95 authentication request signal. Reference numeral 97 denotes the timing at which channel switching is performed from the wireless base station to the designated wireless link channel.

[0004] Normally, a radio mobile station periodically receives a broadcast signal and an incoming signal from a radio base station, and when transmitting a signal to the radio base station, the radio signal is displayed in the signal from the radio base station. The base station ID and the mobile station ID as shown in FIG.
Displayed as 105. The radio base station determines whether or not the base station ID 105 in the transmission signal received from the mobile station is the same as the ID of the own base station, and recognizes that the signal is the transmission signal to the own radio base station only when the ID is the same. Further, when transmitting the channel designation signal to the radio mobile station, the radio base station displays its own radio base station ID and the mobile station ID as the base station ID 114 and the mobile station ID 115 in the channel designation signal as shown in FIG. . As described above, the radio mobile station can make a call to the radio base station and receive a channel designation from the radio base station. That is, in the transmission signal of FIG. 10 and the channel designation signal of FIG.
Since 05 and 115 are the same, signals can be transmitted and received by both the wireless mobile station and the wireless base station. After specifying the channel, the radio base station starts the management of the radio mobile station and the radio resource management. That is, for a radio mobile station having a mobile station ID 105, CPU resources of a radio base station,
Resources such as memory and radios will be allocated. Further, a radio link is established between the radio mobile station and the radio base station, and radio resources are allocated. The wireless base station authenticates the wireless mobile station based on the authentication request 95 and the authentication response 96 to prevent unauthorized wireless mobile station call connection.

[0005]

In the conventional system as described above, if an unauthorized wireless mobile station exists, it is possible to prevent call connection of the unauthorized wireless mobile station by authentication. On the other hand, there is a disadvantage that wireless resources such as a wireless base station resource such as a CPU and a wireless link are wastefully allocated. An object of the present invention is to provide a radio communication system which can solve the above-mentioned drawbacks and can prevent illegal use of base station resources and radio resources by an improper radio mobile station.

[0006]

According to the present invention, in order to achieve the above object, a radio base station (FIG. 2) stores a third identification number for identifying a network of the radio base station (25). -1), means (25-2) for holding a first identification number for identifying the radio base station, and first and third identifications.
Exchange the second identification number encrypted by calculation from another number
A private key and a first identification number
Means for calculating a second identification number from the above, means for holding the obtained second identification number (25-3), and means for periodically transmitting a notification signal including the third identification number. Means for transmitting a signal including a first identification number;
Means for receiving a signal including the identification number of the wireless base station, means for comparing the second identification number with the second identification number held in the radio base station, and only when the comparison result is normal, Means (24) for permitting communication with the radio mobile station, wherein the radio mobile station (FIG. 4) receives the third identification number by a broadcast signal from the radio base station; Means (45-1) for storing the third identification number, means for receiving a signal including the first identification number transmitted from the wireless base station, and means for storing the first and third identification numbers.
A second identification number encrypted by calculation is obtained by calculation.
And a means for transmitting a signal including the second identification number obtained by calculation. The means for calculating the second identification number in the wireless base station and the wireless mobile station may be obtained from the third identification number and the first identification number by calculation, or
The secret key corresponding to the third identification number is stored in advance (25-1 in FIG. 2, 45-1 in FIG. 4), and the secret key and the first
It is a means to obtain by calculation from the identification number of. Further, the exchange (FIG. 3) is characterized in that it has means (35-1) for changing the first identification number with time.

[0007]

According to the present invention, the first to third identification numbers are used,
Further, by keeping the means for calculating the second identification number from the third identification number and the first identification number secret, and by making the calculation method different for each third identification number,
This makes it impossible for an unauthorized wireless mobile station to make the wireless base station receive a transmission signal. Even if the call is forcibly transmitted with an arbitrary second identification number, the radio base station does not receive the signal and cannot receive the channel designation. When the radio base station receives a signal from a radio mobile station, the conventional configuration performs reception of a signal including its own radio base station ID, whereas the configuration of the present invention employs a radio base station ID. Instead, only the signal including the encrypted identification number (second identification number) is received, and the signal processing amount does not increase at all for signal reception. As means for calculating the second identification number, a secret key corresponding to the third identification number is stored in advance, and a second key is calculated from the secret key and the first identification number.
By calculating the identification number, the encryption strength can be further increased. Further, by having means for changing the identification number in time, unauthorized access from an unauthorized wireless mobile station can be more strongly prevented. With this configuration, the radio base station can easily encrypt the identification number for radio access transmitted from the radio mobile station to the radio base station without increasing the amount of processing for signal reception, and as a result, an unauthorized radio It is possible to eliminate unnecessary allocation of radio base station resources and radio resources to mobile stations.

[0008]

FIG. 1 is a diagram showing an embodiment of a system configuration to which the present invention is applied. In the figure, 11-a
And 11-b are radio base stations, 12-a and 12-b
Denotes a radio zone of the radio base stations 11-a and 11-b, 13 denotes an exchange, 14 denotes a radio mobile station, and 15 denotes a local line connecting the exchange and the radio base station. In the figure, the wireless zones of the wireless base stations 11-a and 11-b are 12-a and 12-b, respectively. It is assumed that the wireless base station 14 is in the overlapping portion of the wireless zones 12-a and 12-b and can receive signals from both the wireless base stations 11-a and 11-b . In this embodiment, the wireless base station 11
-A and 11-b, the radio mobile station 14, the switching station 13, the broadcast signal transmitted periodically by the radio base station, and the uplink transmission signal from the radio mobile station to the radio base station, are used for illegal radio movement. Prevents the bureau from using improper resources. Hereinafter, configurations and operations of the radio base station, the radio mobile station, and the exchange in the embodiment of the present invention will be described in detail.

First, a broadcast signal, an upstream transmission signal, and a downstream channel designation signal used in this embodiment will be described. The wireless base station 11 to the wireless mobile station 1 in this embodiment
4 is configured, for example, as shown in FIG. In the figure, 51 is a preamble for synchronizing in the wireless transceiver, 52 is a downlink synchronization word, 53 is a channel type indicating a type of a channel such as a broadcast channel, an individual control channel, an incoming channel, and 54 is a downlink signal. Base station I of the wireless base station 11-a that has transmitted
D and 55 are signals indicating the type of the message, and here indicate, for example, that the notification of the network ID is being performed. Reference numeral 56 denotes a network ID, 57 denotes an annunciation signal data, and 58 denotes a code for detecting a bit error. For example, it is assumed that the radio base station 11 periodically transmits the notification signal in FIG.

[0010] Also, the radio base station 11
The upstream transmission signal to -a is configured, for example, as shown in FIG. In the figure, 61 is a preamble for synchronizing in a wireless transceiver, 62 is an uplink synchronization word, 63 is a channel type indicating a type of a channel such as a broadcast channel, an individual control channel, an incoming channel, etc. Show as channel. 64 is the encryption I of the radio base station 11-a, which is the destination of the upstream signal.
D and 65 are the radio mobile stations 1 that are the transmission sources of the up signal.
A mobile station ID of 66, 66, is a signal indicating the type of message, and here, for example, indicates that transmission is being performed. 67 indicates transmission signal data, and 68 indicates a CRC for bit error detection.

A downlink channel designation signal from the radio base station 11-a to the radio mobile station 14 is configured, for example, as shown in FIG. In the figure, 71 is a preamble for synchronizing in the radio transceiver, 72 is a downlink synchronization word, 73 is a broadcast channel, an individual control channel,
A channel type indicating a type of a channel such as an incoming channel is indicated as an individual control channel in a channel designation signal. 74 is the radio base station 11-
The base station ID 75a is the mobile station ID of the wireless mobile station 14 which is the destination of the signal, and the signal 76 is a signal indicating the type of the message. Here, for example, it indicates that the channel is specified. . 77 is data of a channel designation signal, and 78 is a CRC code for detecting a bit error.

FIG. 2 is a diagram showing a configuration example of a radio base station in this embodiment, for example, the radio base station 11-a. In the figure, reference numeral 21 denotes a wired interface device for connecting to the exchange 13 by wire, 22 denotes a wireless transceiver, 2
3 is a signal reception determining device for determining whether or not the signal received by the wireless transceiver 22 is addressed to the own wireless base station;
Denotes a CPU (central processing unit) for controlling the entire wireless base station, and 25-1 to 25-6 denote memories. When the radio base station 11-a receives the transmission signal (FIG. 6) from the radio mobile station 14, the CPU 24
3, the encrypted ID calculated from the own wireless base station ID is set. The signal reception determination device 23 monitors all the signals received by the wireless transceiver 22, and sends the signal to the CPU 24 when the encryption ID 64 in the received signal matches the encryption ID specified by the CPU 24. Work. For example, when the radio mobile station 14 is the radio base station 11-a
When the signal is transmitted to the wireless base station 11-a, the encrypted ID 64 is the encrypted ID corresponding to the wireless base station 11-a. Will not receive.

The memory 25 (25-1 to 25-6) is, for example, a memory as described below. 25-1 is, for example, the network ID of the own base station (third identification number)
Is stored in the memory. Network I
The secret key paired with D is also stored in this memory,
And the corresponding secret key. As a method of setting the network ID and the secret key, for example,
A method is conceivable in which the same network ID and secret key are written from the exchange 13 to all subordinate radio base stations 11 (here, 11-a and 11-b) when the system is started. The network ID is displayed as a network ID 56 in a broadcast signal shown in FIG. 5 to be described later, and indicates whether or not connection to a wireless mobile station is possible, and specifies a method of calculating an encryption ID. is there. 25-2 is a wireless base station ID (first identification number) indicating the ID of the wireless base station
Is stored in the memory. As a method of writing the present wireless base station ID, for example, there is a method of writing from the exchange 13 as described later. Reference numeral 25-3 denotes a memory for storing an encryption ID (second identification number) used to determine whether a rising signal has been received. As a method of storing this encrypted ID,
For example, a method of loading from the exchange 13 at the time of initial startup, an encryption program memory 25-5 described later,
There is a method of calculating at the time of initial startup using the encryption program described in the above section and storing the result. When the upstream transmission signal shown in FIG. 6 is received, the CPU 24 sets the actual encryption ID in the signal reception determination device 23 in order to perform signal reception.

Reference numeral 25-4 denotes a memory for storing the mobile station ID of the wireless mobile station 14 currently being controlled by the wireless base station. As this mobile station ID, the mobile station ID in the signal is stored as it is when the signal is received. When transmitting a downlink signal to the radio mobile station 14 under control, the mobile station ID is displayed in the transmission signal (for example, the mobile station ID 75 in FIG. 7). A memory 25-5 stores an encryption program for calculating an encryption ID at the time of initial startup. This memory is unnecessary when the calculation of the encryption ID is not performed in the wireless base station. The present encryption program has a one-to-one correspondence with the network ID. For example, it is assumed here that the encryption program is the same for all the radio base stations 11 (11-a, 11-b) under the exchange 13. As a specific example of the encryption program using the secret key, for example, an algorithm according to a known encryption standard DES (Data Encryption Standard) standardized in the United States can be used.
Is used as an original text, a cipher text is calculated by the DES algorithm using the secret key in the memory 25-1 as a key, and this cipher text is used as an encryption ID. Also, for example, an encryption ID
There is also a simple method of calculating the exclusive OR of the base station ID and the network ID. A memory 25-6 stores a control program for controlling the radio base station.

FIG. 3 is a diagram showing a configuration example of the exchange 13 in the present embodiment. In the figure, 31 is a switch circuit, 32 is a radio base station interface for interfacing with the radio base station 11, and 33 is a PSTN or ISDN.
Office line interface for connecting to public networks such as
Reference numeral 4 denotes a CPU for controlling the exchange 13 and 35 (35-1, 35-1, 3
5-2) is a memory. There are the following types of memories. A memory 35-1 stores a base station ID resetting program for resetting a base station ID and the like. The identification number can be changed over time. An example of using this program as an example of the method will be described.
Here, it is assumed that all the radio base stations 11 under the exchange 13 have different numbers. In order to assign a different number to the wireless base station 11 and change the number over time, for example, a different number is assigned to each wireless base station interface 62, an offset value is added to this number, and the modulo is added. A means for calculating is provided. For example, once a day, the offset value is changed and designation is performed for all the radio base stations 11. At the same time, it instructs all wireless base stations 11 to recalculate the encrypted ID. When the calculation of the encrypted ID is not performed by the wireless base station 11, a method of directly transmitting the encrypted ID from the exchange 13 to the wireless base station 11 is also conceivable. 35-2 is the exchange 1
3 is a memory of a control program for controlling the entire system.

FIG. 4 is a diagram showing a configuration example of the radio mobile station 14 in the present embodiment. In the figure, 41 is a handset, 42 is a wireless transceiver, 43 is a signal reception determining device for determining whether a signal received by the wireless transceiver 42 is addressed to the own mobile station, and 44 is a wireless mobile station. A CPU for overall control, 45 is a memory, and 46 is a dial key switch. When the wireless mobile station 14 receives a channel designation signal (FIG. 7) from the wireless base station, the CPU 44 sets the own mobile station ID to the signal reception determination device 43. The signal reception determining device 43 monitors all the signals received by the wireless transceiver 42 and determines whether or not the mobile station ID 105 portion of the received signal matches the mobile station ID set by the CPU 44, and Only when this is done, it serves to send the received signal to the CPU 44. Further, for example,
When receiving a signal from the wireless base station 11-a, the CPU
Reference numeral 44 designates not only the designation of the mobile station ID to the signal reception determination device 43 but also the designation of the base station ID of the wireless base station 11-a, thereby receiving only the signal addressed to the wireless mobile station from the wireless base station Enable.

The memories 45 (45-1 to 45-4) are of, for example, the following types. 45-1
Is a memory for storing the network ID (third identification number) of the receiving wireless base station 11. If the wireless mobile station 14 is a connectable wireless base station, the network ID notified from the wireless base station is stored in the memory 45-1. As a method of determining whether or not the wireless mobile station 14 can be connected to the wireless base station, for example, all connectable network IDs are stored, compared with the network ID in the broadcast signal, There is a method that only allows connection. The secret key and the encryption program to be paired with the network ID are stored in the memory in advance. When the wireless mobile station 14 stores a plurality of network IDs, the same number of secret keys and encryption programs need to be stored in advance. As a method of setting the network ID, secret key, and encryption program stored in advance, for example, a method of writing all network IDs, secret keys, and encryption programs that can be connected at the time of factory shipment can be considered. The encryption program can be realized by a method similar to the method described for the base station.

Reference numeral 45-2 denotes a memory for storing a wireless base station ID (first identification number) indicating the ID of the wireless base station 11. The wireless mobile station 14 stores the base station ID of the wireless base station 11-a to be connected in the memory. Wireless mobile station 14
When searching for a notification signal, for example, the signal reception determination device 43
A broadcast channel, a broadcast message as a message type, and a network ID can be searched for by setting one of IDs that can be received by the mobile station. Upon receiving the broadcast signal from the wireless base station 11-a, the wireless mobile station 14 stores the base station ID 54 in the base station ID memory 45-2 and waits for a signal from the wireless base station. 45-3 is the mobile station ID of the wireless mobile station 14.
Is stored in the memory. As a setting method, for example,
A method of writing at the time of shipment from the factory may be considered. 45-4
Is a memory for storing a control program for controlling the wireless mobile station 14.

FIG. 8 shows an example of transmission when the present invention is applied. With reference to the figure, the radio mobile station 14 and the radio base station 11
The transmission / reception operation performed between -a will be described. Wireless base station 1
The radio mobile station 14 that makes a call to 1-a is, for example, the network ID of the radio base station 11-a in the memory 45-1.
Is calculated from the base station ID in the base station ID memory 45-2 by using an encryption program corresponding to.
Next, in order to transmit the transmission signal shown in FIG. 6, the individual control channel is used as the channel type 63, the encryption ID calculated previously as the encryption ID 64, and the mobile station ID 65 in the mobile station ID memory 65-3. A mobile station ID is set and a call is made. Since the radio base station 11-a performs signal reception,
In advance, the signal reception determination device 23 transmits the encrypted ID
The encryption ID in 5-3 is set. In the signal reception determination device 23, the encrypted ID in the signal from the radio mobile station 14
If 64 matches the set ID, the received signal is sent to CPU 24. The CPU 24 is the signal reception determination device 2
The message type 66 and the data 67 are analyzed for the signal from No. 3 and the mobile station ID 65 is stored in the mobile station ID memory 25-4. Next, in order to transmit the channel designation signal shown in FIG.
, The base station ID in the base station ID memory 45-2 as the base station ID 74, and the mobile station ID7.
5 as the mobile station ID in the mobile station ID memory 45-3;
Channel designation is set as the message type 76, and channel data designated as the data 107 is set, and a channel designation signal is transmitted. As described above, the transmission of the valid wireless mobile station 14 and the channel designation can be performed.

Next, the effectiveness of the present invention will be described by taking an example of an operation when a call is transmitted from an unauthorized radio mobile station.
For example, the radio base station 1 is stored in the memory 45-1 in the radio mobile station.
1-a from an unauthorized wireless mobile station having no encryption program corresponding to the network ID to the wireless base station 11-
Consider a case where an unauthorized wireless mobile station makes a call to a. In this case, the encrypted ID cannot be calculated. In this case, for example, an individual control channel as the channel type 63, arbitrary data as the encryption ID 64, and the mobile station ID
It is assumed that the mobile station ID in the mobile station ID memory 45-3 is set as 65, and the transmission signal shown in FIG. In order to perform signal reception, the wireless base station 11-a sets an encryption ID in the encryption ID memory 25-3 to the signal reception determination device 23 in advance. The signal reception determination device 23 checks the encrypted ID 64 in the signal from the unauthorized wireless mobile station with the set ID, but the CPU 2
No signal is sent to 4. Therefore, a signal from an unauthorized mobile station is not received, and the base station resources and wireless resources of the wireless base station 11-a can be prevented from being wastefully used by the unauthorized wireless mobile station. The method of the present embodiment is particularly effective in the case of the second generation cordless telephone system (digital cordless telephone system) because it occupies a wideband control channel for wireless access until the mobile station is authenticated.

[0021]

According to the present invention, the radio base station can easily encrypt the number for radio access transmitted from the radio mobile station to the radio base station without increasing the amount of processing for signal reception, As a result, it is possible to prevent the useless allocation of the radio base station resources and the radio resources to the unauthorized mobile station, and it is possible to effectively use the resources.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a system configuration when the present invention is applied.

FIG. 2 is a diagram illustrating a configuration example of a wireless base station according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration example of an exchange in one embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration example of a wireless mobile station according to an embodiment of the present invention.

FIG. 5 is a diagram showing a downlink notification signal from a wireless base station to a wireless mobile station in one embodiment of the present invention.

FIG. 6 is a diagram showing an uplink transmission signal from a wireless mobile station to a wireless base station in one embodiment of the present invention.

FIG. 7 is a diagram showing a downlink channel designation signal from a wireless base station to a wireless mobile station in one embodiment of the present invention.

FIG. 8 is a diagram showing a transmission / reception sequence of a transmission signal and a channel designation signal between a wireless mobile station and a wireless base station according to the present invention.

FIG. 9 is a diagram showing a transmission sequence when a radio mobile station transmits a signal to a radio base station in a conventional example.

FIG. 10 is a diagram showing an uplink transmission signal from a wireless mobile station to a wireless base station in a conventional example.

FIG. 11 is a diagram showing a downlink channel designation signal from a wireless base station to a wireless mobile station in a conventional example.

[Explanation of symbols]

 11-a, 11-b Wireless base station 12-a, 12-b Wireless zone 13 Switching station 14 Wireless mobile station 21 Wired interface device 22 Wireless transceiver 23, 43 Signal reception determination device 24, 34, 44 CPU 25, 35 , 45 memory 31 switch circuit 32 wireless base station interface 33 local line interface 41 handset 42 wireless transceiver 46 dial key switch

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-5937 (JP, A) JP-A-7-62950 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 7/24-7/26 H04Q 7/04-7/38 H04L 9/08

Claims (3)

(57) [Claims] 1. A radio communication system having a radio base station, a radio mobile station and an exchange, wherein the radio base station holds a third identification number for identifying a network of the radio base station; means for holding the first identification number identifying the base station, the first and
A second identification encrypted by calculation from the third identification number
Receiving the number from the exchange, or
Means for calculating a second identification number from the identification number, means for holding the obtained second identification number,
Means for periodically transmitting a notification signal including the identification number of
Means for transmitting a signal including the first identification number; means for receiving a signal including the second identification number;
Means for comparing the identification number of the wireless base station with the second identification number held by the wireless base station; and means for permitting communication with the wireless mobile station only when the comparison result is normal. A mobile station for receiving a third identification number based on the broadcast signal from the wireless base station; a storage unit for storing the received third identification number; Means for receiving a signal including the identification number of the first and third identification numbers, and
A wireless communication system comprising: means for calculating the calculated second identification number; and means for transmitting a signal including the calculated second identification number. 2. The wireless communication system according to claim 1, wherein said means for calculating a second identification number in said wireless base station and said wireless mobile station comprises: calculating said second identification number from said third identification number and said first identification number. A wireless communication system which is a means for obtaining by calculation or storing in advance a secret key corresponding to a third identification number, and obtaining from the secret key and the first identification number by calculation. 3. The wireless communication system according to claim 1, wherein the exchange has means for changing the first identification number with time.