JP2008017302A - Short-range wireless communication terminal and transmission power control method - Google Patents

Abstract

To realize P2P short-range wireless communication that reduces power consumption and minimizes radio wave interference to the surroundings.
When performing P2P short-range wireless communication between a terminal A and a terminal B, a connection request is transmitted from the terminal A to the terminal B, and the distance measurement unit 16 uses the response signal from the terminal B to cause the inter-terminal distance Measure. The transmission power control unit 10 performs transmission power control according to the measured distance between terminals, and the channel control unit 20 performs frequency channel control according to the measured distance between terminals. The security level determination unit 17 determines a security level according to the distance between terminals. Communication is performed under the transmission power and frequency channel control at the security level.
[Selection] Figure 1

Description

  The present invention relates to a short-range wireless communication terminal that performs short-range wireless communication by peer-to-peer (hereinafter referred to as “P2P”) and a transmission power control method in peer-to-peer short-range wireless communication.

  In communication using a general wireless LAN network, a wireless communication terminal connects to an access point (AP) via air, and the access point inquires an authentication server installed on the wireless LAN network to perform user authentication. When the authentication of the wireless communication terminal is successful, a session is established between the wireless communication terminal and the connection partner so that IP communication can be performed.

  There is also a P2P short-range wireless communication system in which terminals directly communicate with each other without using a wireless LAN network access point (AP). As P2P short-range wireless communication, for example, infrared communication using IrDA or the like and Bluetooth (registered trademark) communication using weak radio waves are known. Conventional P2P short-range wireless communication is mainly limited to communication with a very short distance of about several centimeters between terminals and a small amount of information, and the connection time is also short.

  Recently, there is an increasing need for high-speed data communication even in P2P short-range wireless communication, and there is also an increasing need for extending the communication distance in order to realize high mobility communication. For example, OFDM can be used as a digital modulation method for speeding up data communication. In multi-carrier communication such as OFDM, high-speed data communication is realized by using a large number of frequency channels as carrier waves. Further, in order to realize communication with high mobility, it is conceivable to increase transmission power and extend a communication distance and reduce transmission errors.

  In a wireless communication system, it has been proposed to reduce power consumption of a wireless communication device while maintaining a suitable state without being affected by reception characteristics due to radio wave environment (see, for example, Patent Document 1). In the wireless communication system described in Patent Literature 1, when wireless communication is performed between the first wireless communication device and the second wireless communication device, the received power received by the first wireless communication device is determined. In addition, the reception signal quality is determined, a transmission power control request for controlling the transmission power of the second wireless communication device is created based on these determination results, and the first wireless communication device transmits to the second wireless communication device. The transmission power control request is superimposed on the signal to be transmitted and transmitted to the second wireless communication apparatus.

Further, in order to cope with the change in communication quality according to the distance between terminals, a wireless LAN communication technique is proposed in which the system is switched according to the communication quality (see, for example, Patent Document 2).
JP 2005-191762 A JP 2003-324443 A

  However, in P2P short-range wireless communication, in order to achieve high-speed data communication and high-mobility communication, increasing the transmission power and performing data communication using all frequency channels increases the power consumption at the terminal. There is a problem such as. Further, when the transmission distance is increased by increasing the transmission power, the radio wave interference range to other terminals other than the communication partner is widened, which causes a problem that the number of frequency channels that can be used in other terminals is limited. On the other hand, if the number of frequency channels to be used is reduced, the communication speed decreases, so the connection time with the counterpart terminal becomes longer and the power consumption increases.

  The present invention has been made in view of such a point, and by performing transmission power control and / or frequency channel selection adapted to the communication distance, it is possible to reduce power consumption and minimize radio wave interference to the surroundings. An object of the present invention is to provide a short-range wireless communication terminal and a transmission power control method for realizing suppressed P2P short-range wireless communication.

  The present invention is a wireless communication terminal that performs near field communication on a peer-to-peer basis, a distance measuring unit that measures a distance to a partner terminal, and a transmission power that is adapted according to the distance between the terminals measured by the distance measuring unit Transmission power control means for controlling the transmission power, and communication control means for connecting to the counterpart terminal with the transmission power controlled by the transmission power control means.

  According to this configuration, since transmission power is adaptively controlled according to the distance between terminals, the transmission power can be reduced and the power consumption can be suppressed as the distance between terminals is closer.

  Further, the present invention is a wireless communication terminal for performing near field communication on a peer-to-peer basis, a distance measuring unit for measuring a distance to the partner terminal, and a partner terminal according to the distance between the terminals measured by the distance measuring unit. Channel control means for adaptively controlling the frequency channel used for the connection, and communication control means for connecting to the partner terminal using the frequency channel controlled by the channel control means.

  According to this configuration, since frequency channels are adaptively controlled according to the distance between terminals, the number of frequency channels can be increased and the connection time can be shortened as the distance between terminals approaches. Electric power can be suppressed.

  Further, the present invention is a wireless communication terminal that performs peer-to-peer short-range wireless communication, a distance measuring unit that measures a distance to a partner terminal, and a transmission power according to a distance between terminals measured by the distance measuring unit. Transmission power control means for adaptively controlling, channel control means for adaptively controlling a frequency channel used for connection with a counterpart terminal according to the distance between terminals measured by the distance measuring means, and the channel control means And a communication control means for connecting to the counterpart terminal using the transmission power controlled by the transmission power control means.

  According to this configuration, since the transmission power and frequency channel are adaptively controlled according to the distance between terminals, the transmission power can be lowered as the distance between terminals is closer, and the number of frequency channels can be increased. Connection time can be shortened, thereby reducing power consumption.

  The short-range wireless communication terminal further includes a security level determining unit that automatically selects a security level according to the distance between the terminals measured by the distance measuring unit, and the communication control unit includes: It is characterized by connecting to a partner terminal based on the selected security level.

  According to this configuration, the security condition can be adaptively changed according to the distance between terminals, and security communication adapted to the communication distance can be performed.

  In the short-range wireless communication terminal, the distance measuring means is configured to measure a distance between terminals from a response signal indicating a terminal position returned from the counterpart terminal in response to a request signal transmitted from the own terminal.

  In the short-range wireless communication terminal, the distance measuring means is configured to measure the distance between the terminals from the time until the response signal returned from the counterpart terminal is received in response to the request signal transmitted from the own terminal.

  The transmission power control method in peer-to-peer short-range wireless communication according to the present invention measures the distance between terminals when a communication terminal performs near-field wireless communication in peer-to-peer, and transmits the transmission power according to the measured distance between terminals. And the terminals are connected with transmission power corresponding to the distance between the terminals.

  The frequency channel control method for peer-to-peer short-range wireless communication according to the present invention measures a distance between terminals when a communication terminal performs short-range wireless communication by peer-to-peer, and connects to a partner terminal according to the measured distance between terminals. The frequency channel to be used is controlled adaptively, and the terminals connect using the frequency channel according to the distance between the terminals.

  According to the present invention, by performing transmission power control and / or frequency channel number selection adapted to the communication distance, P2P short-range wireless communication with less power consumption and minimizing radio wave interference to the surroundings is realized. can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The wireless communication apparatus according to the present embodiment is a portable wireless communication terminal on which a near field wireless communication function based on P2P is installed. Hereinafter, a case will be described as an example in which a mobile phone device or a portable personal computer as a wireless communication device having a short-range wireless communication function performs P2P communication. In this embodiment, as P2P short-range wireless communication, infrared communication or Bluetooth (registered trademark) communication using IrDA or the like capable of realizing a communication distance of several centimeters to several tens of meters is used. Can also be applied.

  FIG. 1 is a sequence showing a procedure for performing multi-carrier P2P wireless communication in which wireless communication terminals (hereinafter abbreviated as terminals) A and B according to the present embodiment selectively use a plurality of frequency channels as carriers. FIG. Assume that one terminal A transmits a connection request signal. The other terminal B is arranged within a range where the maximum transmission power of the terminal A can reach and can receive a connection request signal.

  When one terminal A transmits a connection request signal, the other terminal B that has received the connection request signal returns a response signal. If the time taken from when the other terminal B receives the connection request signal to when the response signal is transmitted is known, one terminal A can measure the distance from the reception time of the response signal to the terminal B. . That is, since the time at which the connection request signal is transmitted and the time at which the response signal is received at the terminal A is known, the radio wave transmission time is obtained by removing the time loss at the terminal B, and the radio wave propagation speed and transmission time From this relationship, the distance between the terminal A and the terminal B is found.

  Note that the distance from the terminal A to the terminal B can be obtained without using the above method. For example, the terminal B that has received the connection request signal may return its position information to the terminal A.

  Terminal A selects a security level corresponding to the distance to terminal B, and selects transmission power and the number of frequency channels to be used. If the distance between terminals is several centimeters or less, a highly secure space can be secured, so neither authentication nor encryption is required. However, if the distance between terminals is several meters or more, there may be terminals other than the communication partner. Authentication and encryption are required. Furthermore, since it becomes difficult to secure a secure space when the distance between terminals is several tens of meters or more, advanced authentication and encryption are necessary. In the present embodiment, the security level is selected based on the relationship between the inter-terminal distance and the security level as described above.

  If the distance between terminals is several cm or less, it is possible to connect to the partner terminal even with low transmission power. However, if the distance between terminals is several meters or more, it is impossible to connect to the partner terminal unless the transmission power is somewhat large. Furthermore, when the distance between terminals is several tens of meters or more, it is difficult to connect to the partner terminal unless communication is performed with a larger transmission power. In the present embodiment, the necessary minimum transmission power corresponding to the distance is selected based on the relationship between the terminal-to-terminal distance and the connectable transmission power as described above.

  Also, if the distance between terminals is several centimeters or less, even if the number of frequency channels used for data communication with the other terminal is maximized, if the transmission power is reduced, it will not be an interference wave to other terminals other than the other terminal, When the distance between terminals is several meters or more, a certain amount of transmission power is required, so it is necessary to reduce the number of frequency channels. Furthermore, when the distance between terminals is several tens of meters or more, a larger transmission power is required, so it is necessary to perform communication using a small number of frequency channels. In the present embodiment, the maximum number of frequency channels that can suppress radio wave interference with surrounding terminals is selected based on the above-described relationship between the distance between terminals and the number of usable frequency channels.

  For example, as shown in FIG. 2, a correspondence table of inter-terminal distance (communication distance), security level, transmission power, and number of frequency channels is prepared, and the corresponding security is based on the acquired inter-terminal distance information. Automatically select the level, transmission power and number of frequency channels. In FIG. 2, the inter-terminal distances a, b, and c have a magnitude relationship of a <b <c. User authentication corresponding to the selected security level is performed, and P2P wireless communication is performed with the selected transmission power and the number of frequency channels.

FIG. 3 is an explanatory diagram showing specific examples of security conditions and optimum transmission power corresponding to the distances between terminals.
When the distance between the terminal A and the terminal B is about 2 cm, a highly secure space can be secured, so the security level is set to the “minimum level”. The security content at the “minimum level” is that authentication confirmation and encryption are not performed. A specific IP number that can be received by all terminals is used for calling the other terminal. Since the terminals are very close to each other, interference control such as CSMA / CA is not performed. In addition, any transmission power that realizes a radio wave reach slightly longer than 2 cm may be used, and the transmission power to be set is “very low transmission power”. Although the number of frequency channels is not shown in FIG. 3, since the transmission power is extremely low, the possibility of radio wave interference with surrounding terminals is low, so data communication can be performed using all available frequency channels. .

  When the distance between the terminal A and the terminal B is about 10 cm, a secure space can be secured, so the security level is set to the “minimum level”. Authentication confirmation and encryption are not performed, and a specific IP number that can be received by all terminals is used for calling to the other terminal. However, interference control such as CSMA / CA is performed. In addition, since transmission power that realizes a radio wave reach slightly longer than 10 cm may be used, the transmission power to be set is “low transmission power”. Since the transmission power is low, the possibility of radio wave interference with surrounding terminals is low, and therefore data communication can be performed using a number of frequency channels close to the total number of usable frequency channels.

  When the distance between the terminal A and the terminal B is within about 1 m (excluding the extremely short distance up to around 10 cm), a somewhat secure space can be secured, so the security level is set to “low level”. The security content at “low level” is such that simple authentication is performed but encryption is not performed. Since there is a possibility that there is a terminal other than the communication partner in the communication range (range of about 1 m radius), the call to the partner terminal is performed using the IP number of the communication partner. As a simple authentication, the communication partner is confirmed by checking the IP number. Interference control is performed because there is a sufficient possibility of interference with other terminals. In addition, since transmission power for realizing a radio wave reach of about 1 m is required, the transmission power to be set is “medium transmission power”. Since there is a possibility that a terminal other than the communication partner exists in the communication range (a range of about 1 m in radius), it is desirable that the frequency channel to be used is slightly reduced from the maximum frequency channel number.

  When the distance between the terminal A and the terminal B is about 5 m or less (except for the distance of 1 m or less), a secure space cannot be secured, so the security level is set to “medium level”. The security content at the “medium level” is such that high-level authentication and simple encryption are performed. The call to the partner terminal is made using the IP number of the communication partner. As advanced authentication, authentication using an SSID (Service Set Identifier) which is an identifier of an access point can be mentioned. In addition, since transmission power that realizes a radio wave reach of up to about 5 m is required, the transmission power to be set becomes “large transmission power”. In addition, since there is a higher possibility that there is a terminal other than the communication partner in the communication range (a radius of about 5 m), it is desirable to further reduce the frequency channels to be used.

  If the distance between the terminal A and the terminal B is about 5 m or more (excluding distances less than 5 m), a secure space cannot be secured and there is a possibility that another terminal exists, so the security level is set to “high level”. To do. The security content at “high level” is such that high-level authentication and high-level encryption are performed. Since there is a possibility that a terminal other than the communication partner exists, MAC authentication using a MAC address that is an ID number unique to the terminal is performed as advanced authentication. Further, since transmission power that realizes a radio wave reach distance of about 5 m or more is necessary, the transmission power to be set is the maximum “maximum transmission power”. Since there is a higher possibility that there is a terminal other than the communication partner in the communication range (range of radius 5 m or more), it is desirable to reduce the frequency channels to be used as much as possible.

  In the example shown in FIG. 3, the transmission power (and the number of frequency channels and the security level) are divided into five levels according to the distance between terminals. However, it is not limited to the above setting, and the number of divisions can be changed as appropriate It is. In the following description, it is assumed that it is divided into three stages as shown in FIG.

  Next, the configuration of the terminal A will be described. Terminal B also has the same functional blocks as terminal A.

  FIG. 4 is a functional block diagram of the terminal A, and mainly shows a portion related to a function for adaptively changing the transmission power, frequency channel, and security level at the time of connection. The transmission power control unit 10 is a part that adaptively controls the transmission power at the time of partner connection according to the distance between terminals, and determines the transmission power based on the table data shown in FIG. The channel control unit 20 is a part that adaptively controls the used frequency channels at the time of partner connection according to the distance between terminals, and determines the number of used frequency channels based on the table data shown in FIG.

  The IP control unit 11 is a part that controls connection (authentication and data communication) with the counterpart terminal based on the determined security level. The wireless IP signal transmission unit 12 and the wireless transmission unit 13 convert the transmission packet into a wireless signal and send it out, and the wireless reception unit 14 and the wireless IP signal reception unit 15 convert the reception signal into a reception packet. These components constitute a communication control means.

  The distance measuring unit 16 is a part that calculates the inter-terminal distance from the signal indicating the position of the counterpart terminal returned at the time of connection. It is assumed that the current position information is supplied from position detection means (not shown). The distance between terminals is calculated from the position information of the partner terminal and the position information of the own terminal. As described above, the distance between terminals may be calculated from the transmission time of the connection request signal and the reception time of the response signal.

  The security level determination unit 17 constitutes a security level determination unit that automatically selects a security level to be applied to communication with the terminal B based on the distance between terminals calculated by the distance measurement unit 16. The security level data table 18 stores a correspondence table between the distance between terminals and the security level. The security level determination unit 17 notifies the security unit 19 of the security level determined based on the distance between terminals.

  The security unit 19 is a part that manages the connection with the partner terminal at the determined security level. The security unit 19 instructs the IP control unit 11 to perform authentication and encryption according to the security level. The IP control unit 11 performs user authentication from the IP number, SSID, or MAC address of the counterpart terminal according to the security level, while executing transmission data encryption and reception data decryption.

  The application control unit 21 is a part that executes application processing related to security. The application control unit 21 outputs to the output unit 22 a screen for requesting an operation input from the user in the process from the activation of the P2P mode to the start of communication. The output unit 22 includes a display unit and a microphone speaker.

  The storage unit 23 stores information related to security. For example, the IP number used for calling all terminals, its own IP number, SSID, and MAC address are stored, and the IP number and SSID of the other terminal acquired by communication with other terminals or user input , MAC address is stored. In addition, information regarding the encryption method is stored.

  Next, an operation for adaptively changing the transmission power, the frequency channel, and the security level according to the distance between terminals at the time of connection when performing short-range wireless communication between the terminal A and the terminal B will be described in detail.

  FIG. 5 is a sequence showing the connection procedure according to the security level, the transmission power at the time of connection, and the number of frequency channels.

  In terminal A, the P2P mode is activated to search for surrounding terminals. For searching for peripheral terminals, a specific IP number for calling all terminals is read from the storage unit 23 and used. If the IP number of the communication partner has already been acquired, searching for peripheral terminals is not necessary. At this time, the transmission power is set to a large transmission power that can reach 5 m or more, and the use frequency channel has a small data amount and a small number is selected from the viewpoint of preventing interference.

  Next, the terminal A transmits a connection request specifying a bearer and an application to the communication partner. For example, the wireless LAN is designated as the bearer, and the SIP connection is designated as the application.

  Terminal B determines whether it can respond by receiving the connection request transmitted by terminal A. For example, if the terminal B does not support the SIP designated for the application, a response signal indicating that connection is impossible is returned. When the terminal B determines that a response to the connection request is possible, the terminal B returns a response signal indicating that the connection is possible. In this embodiment, the position information of terminal B is added to the response signal indicating that connection is possible and transmitted.

  When the terminal A receives the response signal indicating that the connection is possible in response to the connection request, the distance measuring unit 16 calculates the distance from the terminal A to the terminal B from the position information added to the response signal. If the terminal does not have a function of adding its own location information to the response signal, the distance between the terminals may be calculated from the connection request signal transmission time and the connection response signal reception time. .

  The transmission power control unit 10 of the terminal A takes in the inter-terminal distance from the distance measurement unit 16 and refers to the correspondence table between the inter-terminal distance and the transmission power shown in FIG. The transmission power suitable for is determined. In connection with the terminal B, the transmission power control unit 10 controls the wireless transmission unit 13 so that the transmission power of the transmission signal transmitted from the wireless transmission unit 13 becomes the determined transmission power. Further, the channel control unit 20 takes in the inter-terminal distance from the distance measuring unit 16 and refers to the correspondence table between the inter-terminal distance and the frequency channel shown in FIG. 2 and is suitable for the current distance between the terminal A and the terminal B. Determine the frequency channel. In connection with the terminal B, the radio transmission unit 13 is controlled from the channel control unit 20 so that the frequency channel used for the carrier in the multi-carrier modulation in the radio transmission unit 13 becomes the determined frequency channel. Further, the security level determination unit 17 takes in the distance between terminals from the distance measurement unit 16 and refers to the correspondence table between the distance between terminals and the security level shown in FIG. Determine the appropriate security level. A correspondence table between the distance between terminals and the security level is stored in advance in the security level data table 18. The security level determined by the security level determination unit 17 is notified to the security unit 19. The security unit 19 performs security management based on the determined security level. If the security level is 1, the IP control unit 11 is instructed to perform security contents such that authentication and encryption are not performed. The IP control unit 11 switches the connection procedure according to the notified security level.

  In the case of security level 1, the IP control unit 11 immediately starts communication with the terminal B without performing authentication and encryption. When the security level determination unit 17 determines the security level 1, the inter-terminal distance x is a or less. Therefore, the transmission power control unit 10 refers to the correspondence table between the distance between terminals and the transmission power shown in FIG. 2 and instructs the wireless transmission unit 13 to set “low” as the transmission power. Further, the channel control unit 20 refers to the correspondence table between the distance between terminals and the frequency channel shown in FIG. 2 and instructs the radio transmission unit 13 to “many” as the frequency channel. FIG. 6A is a diagram illustrating frequency channels when the frequency channels are controlled to be “multiple”. As a result, when the inter-terminal distance x is less than or equal to “a”, the transmission power is controlled to a small value and the use frequency channel is controlled to the maximum number of channels. The effect of reducing power consumption by (high-speed data communication) can be expected.

  On the other hand, if the security level notified from the security level determination unit 17 is 2, the security unit 19 proceeds to an authentication process corresponding to the security level. That is, the terminal A sends an authentication request for the partner terminal (terminal B) and transmits the identification information of the terminal (terminal A). When the security level determination unit 17 determines the security level as “2”, the inter-terminal distance x is a <x <b. Accordingly, the transmission power control unit 10 controls the radio transmission unit 13 to “medium” with reference to the correspondence table between the distance between terminals and the transmission power shown in FIG. Further, the channel control unit 20 refers to the correspondence table between the distance between terminals and the frequency channel shown in FIG. 2 and controls the frequency channel used by the wireless transmission unit 13 to “medium”. FIG. 6B is a diagram illustrating a frequency channel when the frequency channel is controlled to “medium”. As a result, when the inter-terminal distance x is a <x <b, the transmission power is controlled to a value that can reach the distance b, and the used frequency channel can secure a certain communication speed, and the surroundings Since the number of channels is controlled so as to prevent interference with other terminals, the transmission power can be suppressed and the connection time can be suppressed to some extent, so that an effect of reducing power consumption can be expected.

  As shown in FIG. 5, in the case of security level 2, the authentication request and the identification information of the own terminal are transmitted to the counterpart terminal for authentication and then communication is started. Connection data for establishing a communication link with the partner terminal at the start of communication with the partner terminal (data necessary for connection between terminals according to the security level such as authentication method and authentication information, encryption method and encryption information) Is required. If connection data related to the counterpart terminal is not held, the connection data is requested from the counterpart terminal, and communication is started after the connection data is acquired. As a method for easily obtaining connection data from a partner terminal, there is a method for exchanging data by bringing the terminals close to security level 1.

  Terminal B determines whether it can respond to the authentication request received from terminal A. If the authentication is not successful from the identification information of the terminal A, it is determined that the response is impossible. However, it is determined that the response is not possible even when the necessary authentication method is not supported. If it is determined that the response is not possible, a response signal indicating that the authentication is not possible is returned. If the terminal A can be authenticated, a response indicating that authentication is possible and the identification information of the own terminal (terminal B) are returned.

  When the terminal A receives the identification information of the terminal B together with the information that can be authenticated from the terminal B, the terminal A identifies the partner terminal using the identification information, compares the necessary authentication level with the received data, and connects. Determine if you can. In security level 2, the other terminal is specified by the IP number as the authentication level, and authentication using the SSID is performed. As a result, if authentication fails, a response signal indicating that connection is impossible is returned. If the authentication is successful, communication with the terminal B is started. At this time, the wireless transmission unit 13 is controlled to transmit power “medium” and a use frequency channel “medium”.

  In the case of the security level 3, the terminal A requests connection data (encrypted data such as an encryption method and a key) necessary for the encrypted connection from the terminal B. When the security level determination unit 17 determines the security level as “3”, the inter-terminal distance x is x> b. Therefore, the transmission power control unit 10 refers to the correspondence table between the distance between terminals and the transmission power shown in FIG. Further, the channel control unit 20 refers to the correspondence table between the terminal-to-terminal distances and the frequency channels shown in FIG. 2 and controls the use frequency channel of the wireless transmission unit 13 to “low”. FIG. 6C is a diagram showing the frequency channel when the frequency channel is controlled to “low”. As a result, when the inter-terminal distance x is x> b, the transmission power is controlled to the maximum value that can reach farther than the distance b, and the used frequency channel prevents interference with surrounding terminals. It is controlled to a limited number of channels. Therefore, although the effect of reducing power consumption is reduced, interference with surrounding terminals can be prevented as much as possible.

  When the terminal B is requested by the terminal A for the encrypted data required for the encrypted connection, the terminal B determines whether or not it can respond to the request. Encrypted data cannot be passed unless advanced authentication is imposed. In addition, the terminal B may not support advanced encryption communication. In such a case, a connection impossible response signal indicating that encrypted connection cannot be made is returned. Further, when the advanced authentication is successful and the terminal B supports the encrypted communication, a response indicating that the encrypted connection is possible and the information of the own terminal (encrypted data, etc.) are returned. As will be described later, the terminals can be brought close to the security level 1 and data necessary for encryption can be exchanged so that encrypted communication is possible.

  When the terminal A receives a response signal indicating that encrypted connection is possible from the terminal B, the terminal A verifies the required encryption level and the received data. When the encryption level of the terminal B does not satisfy the encryption level required by the security level 3, a response signal indicating that connection is impossible is transmitted to the terminal B. Further, when the encryption level of the terminal B satisfies the encryption level required by the security level 3, communication is performed using the encryption method. At this time, the wireless transmission unit 13 is controlled to have a transmission power “high” and a use frequency channel “low”.

  Thus, by determining the distance between terminals when connecting terminal A and terminal B and adaptively changing the security level, transmission power, and frequency channel according to the distance between terminals, a secure space can be secured. When the terminals are close to each other, communication can be started without performing authentication and encryption, and high-speed data communication can be performed with small transmission power to save power. Further, it is possible to solve the problem that the time until the start of communication becomes long due to a complicated authentication procedure or the like. In addition, if the terminals are so far apart that secure space cannot be secured, authentication and encryption are performed according to the required security level, so that appropriate security can be secured and the number of frequency channels is limited to the surrounding terminals. Can be prevented.

  FIG. 7 is a flowchart showing how the transmission power, frequency channel, and security level follow when the distance between terminals changes.

  When terminal A starts connection control for terminal B and receives a response signal from terminal B, terminal A measures the distance between terminals using the response signal (step S40). If the inter-terminal distance x is less than the distance a (step S41), the security level is determined as “1” (step S42-1), the transmission power is controlled to be “small”, and the frequency channel is controlled to be “many” (step). S42-2). Then, data communication is enabled without authenticating the partner terminal (step S43).

  If there is no instruction to increase the distance between terminals (step S44), data communication is continued (step S45). If the distance between the terminals is reduced in order to obtain connection data (authentication / encryption data) corresponding to a high security level, the process proceeds to step S46 to satisfy the security level corresponding to an arbitrary distance. Data for authentication / encryption is transmitted and received to exchange data (step S46). Then, the distance between the terminals is increased to an arbitrary distance (step S47), and from the state in which data communication is possible (step S48), the connection request credit and the response signal are transmitted and received between the terminal A and the terminal B.

  When the terminal distance x is between the distance a and the distance b as a result of measuring the terminal distance x (step S49), the terminal A changes to “2”, which is a security level for authentication (step S50). -1). Further, the transmission power is controlled to “medium” and the frequency channel is controlled to “medium” (step S50-2). Then, it is determined whether or not authentication data is stored (step S51). If the data is stored, the data communication is enabled (step S52). If there is a communication instruction, the communication is started after authentication (step S53).

  On the other hand, if it is determined in step S51 that the authentication data is not stored, it is determined whether the terminal distance can be reduced (step S54). Transition is made to return to step S40 (step S55). If the inter-terminal distance x is less than a after step S55, the process proceeds to step S46 in the determination of step S44. When an instruction indicating that the terminal distance cannot be reduced is input in the process of step S54, a response signal indicating that connection is impossible is transmitted (step S56).

  If the terminal distance x is greater than the distance b as a result of measuring the terminal distance x (step S49), the terminal A changes the security level to “3” for encryption (step S57-1). . Further, the transmission power is controlled to be “large” and the frequency channel is controlled to be “low” (step S57-2). It is determined whether or not the data for encryption is stored (step S58). If the data is held, the data communication is enabled (step S59). If there is a communication instruction, encrypted communication is started (step S60). If the data for encryption is not held (step S58), the process proceeds to step S54. In order to acquire the encryption data at the security data level 3, the distance between the terminals is reduced, and the encryption data is exchanged and acquired in the process of step S46.

  In this way, since the security level is changed according to the distance between the terminals, when there is no connection data when connecting to the other terminal, the connection data is automatically exchanged by reducing the distance between the terminals, It is possible to easily shift to connection with a terminal having no connection data.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, not only the combination of transmission power and frequency channel, but also the effect of reducing power consumption can be achieved only by transmission power control according to the distance between terminals, and control of the frequency channel according to the distance between terminals Even if it is only, the effect of reducing power consumption can be expected by shortening the connection time. Also, the transmission power and frequency channel may be controlled so as to change smoothly instead of stepwise according to the distance between terminals.

  The present invention is applicable to a wireless communication terminal that performs P2P short-range wireless communication in which the distance between terminals changes.

The sequence diagram which shows the procedure for the wireless communication terminal which concerns on one embodiment to perform P2P short-distance wireless communication The figure which shows the correspondence of distance between terminals and security level, transmission power and frequency channel Explanatory diagram showing specific examples of security conditions and transmission power corresponding to the distance between terminals Functional block diagram of the wireless communication terminal according to the above embodiment Sequence diagram showing the connection procedure according to the security level, and the transmission power and frequency channel control contents together (A) The figure which shows the frequency channel used when the distance between terminals is very near, (b) The figure which shows the frequency channel used when the distance between terminals is an intermediate distance, (c) The distance between terminals is a long distance Diagram showing frequency channels used for Flow diagram showing how the security level, transmission power and frequency channel change when the distance between terminals changes

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transmission power control part 11 IP control part 12 Wireless IP signal transmission part 13 Wireless transmission part 14 Wireless reception part 15 Wireless IP signal reception part 16 Distance measurement part 17 Security level determination part 18 Security level data table 19 Security part 20 Channel control part 21 Application Control Unit 22 Output Unit 23 Storage Unit

Claims (8)

A wireless communication terminal that performs near field communication on a peer-to-peer basis,
Controlled by the distance measuring means for measuring the distance to the counterpart terminal, the transmission power control means for adaptively controlling the transmission power according to the distance between the terminals measured by the distance measuring means, and the transmission power control means A short-distance wireless communication terminal comprising: a communication control means for connecting to a partner terminal with transmission power. A wireless communication terminal that performs near field communication on a peer-to-peer basis,
Distance measuring means for measuring the distance to the partner terminal, channel control means for adaptively controlling a frequency channel used for connection with the partner terminal according to the distance between the terminals measured by the distance measuring means, and the channel A short-range wireless communication terminal comprising: a communication control unit that connects to a partner terminal using a frequency channel controlled by the control unit. A wireless communication terminal that performs near field communication on a peer-to-peer basis,
Distance measuring means for measuring the distance to the partner terminal, transmission power control means for adaptively controlling transmission power according to the distance between the terminals measured by the distance measuring means, and the terminal measured by the distance measuring means Channel control means for adaptively controlling the frequency channel used for connection with the partner terminal according to the distance, and the transmission power controlled by the transmission power control means using the frequency channel controlled by the channel control means And a communication control means for connecting to the other terminal. Security level determination means for automatically selecting a security level according to the distance between the terminals measured by the distance measurement means;
The short-range wireless communication terminal according to any one of claims 1 to 3, wherein the communication control means connects to a counterpart terminal based on a security level selected by the security level determination means.   5. The distance measurement unit measures an inter-terminal distance from a response signal indicating a terminal position returned by a counterpart terminal in response to a request signal transmitted from the terminal itself. 6. The short-range wireless communication terminal described.   5. The distance measurement unit measures the distance between terminals based on a time until receiving a response signal returned from the counterpart terminal in response to the request signal transmitted from the terminal itself. A short-range wireless communication terminal according to claim 1.   When communication terminals perform short-range wireless communication on a peer-to-peer basis, the distance between terminals is measured, and the transmission power is adaptively controlled in the communication terminals according to the measured distance between terminals. A transmission power control method in peer-to-peer short-range wireless communication, wherein connection is performed with transmission power.   When a communication terminal performs short-range wireless communication on a peer-to-peer basis, the distance between terminals is measured, and the frequency channel used for connection with a partner terminal is adaptively controlled according to the measured distance between terminals. A frequency channel control method in peer-to-peer short-range wireless communication, characterized in that connection is performed using a frequency channel corresponding to the distance between the two.

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