Mobile communication system, mobile terminal, and mobile communication method

The present invention relates to a mobile communication system, a mobile terminal, and a mobile communication method, and in particular, mobile communication capable of communicating even with a mobile terminal (hereinafter, may be simply referred to as a terminal) located outside the communication range. Regarding systems, mobile terminals, and mobile communication methods.

Usually, in a mobile communication system such as a mobile phone system, each mobile terminal communicates directly with a base station. Therefore, if a mobile terminal is located outside the communication range of any base station, the mobile terminal cannot communicate.

For example, the mobile terminal is physically far from any base station and is outside the communication area. Although the area coverage of typical mobile phone systems in Japan is relatively high and is gradually increasing, many areas in rural areas and mountainous areas are still outside the communication area. This is shown in Fig. 7. For simplicity, FIG. 7 shows two base stations (base station A (71) and base station B (74)) and their communicable areas 72 and 75, respectively. The mobile phones 73 and 76 are located in the communicable area of either base station, but the mobile phones 77 and 78 are far from any base station, and the place where both mobile phones are located is outside the communicative area.

Further, even if the mobile terminal is close to the base station but is locally in a place where the electric field strength is weak due to the influence of obstacles (buildings, etc.), the mobile terminal cannot communicate. Furthermore, even if there is sufficient electric field strength at the start of communication and communication is possible without problems, if the terminal moves during communication and approaches a place where the electric field strength is weak, communication will be interrupted in the middle. There is also.

In order to improve these problems, some proposals have been made to establish a connection with an appropriate base station and substantially expand the communication area by using another mobile terminal as a relay station. .. For example, in Patent Document 1, a mobile communication terminal device outside the service area of a wireless base station relays communication to another mobile communication terminal device within the communication range and within the service area of the wireless base station, and the wireless base station and the wireless base station. The technology of communicating is disclosed. Similar techniques are also disclosed in Patent Document 2, Patent Document 3, and Patent Document 4.

On the other hand, some proposals have been made to adopt radio wave arrival direction estimation technology in mobile terminals in order to improve the reliability of communication between each terminal and each base station. For example, Patent Document 5 discloses a technique in which a plurality of chip antennas are mounted on a PHS (Personal Handy-phone System) terminal and the direction of a base station is displayed on a liquid crystal screen. Further, Patent Document 6 discloses a technique of mounting an array antenna on a wireless communication device for mobile communication and estimating the direction of incoming radio waves. However, these are technologies that estimate the direction of arrival of radio waves when a mobile terminal communicates with a base station, and although the certainty of communication between each terminal and the base station is improved to some extent, other special qualities are obtained. No improvement will occur.

<patcit num="1"><text>JP-A-7-162935</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2000-049690</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2001-186076</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 2003-179536</text></patcit><patcit num="5"><text>Japanese Unexamined Patent Publication No. 2002-016975</text></patcit><patcit num="6"><text>Japanese Unexamined Patent Publication No. 2003-348004</text></patcit>

<p> In the prior art as described in Patent Documents 1 to 4, communication is performed by an extension antenna possessed by a normal mobile terminal, an antenna existing inside the terminal, or the like. However, since these antennas do not have remarkable directivity, it is not possible for the terminal to grasp the direction in which the radio wave arrives, that is, the direction in which another terminal that should request the relay of communication exists. Therefore, the terminal must extract the target signal from innumerable unnecessary waves and noise, and there is a problem that the connection established between the terminal and the base station after being relayed by another terminal is easily disconnected. It was. This challenge has prevented the adoption of this technology in real-world mobile communication systems. In addition, this tendency of being easily disconnected becomes exponentially remarkable as the number of terminals involved in relay increases, and even if this technology is adopted in an actual mobile communication system, it is about one step. There was a problem that it was limited to relaying and the actual communication area did not expand so much.</p><p> In addition, the above-mentioned conventional technology has an advantage that the terminal requesting the relay of communication can communicate from outside the communication area, but there is a risk that the communication content is leaked from the terminal that accepts the relay of the communication. There is a demerit that there is. On the other hand, for a terminal that accepts relay of communication, there is a demerit that hardware resources such as electric power and CPU power must be provided for communication that has nothing to do with the own terminal. In addition, as a whole communication system, if each terminal searches for other terminals in the vicinity one after another and establishes a connection, and if the connection is disconnected against the intention of the user for some reason, the terminal is searched again. Since the connection is repeatedly established, there is a problem that the communication traffic increases and a great load is applied to the entire communication system.</p><p> The present invention has been made to solve such a problem. That is, an object of the present invention is to make it difficult to disconnect a connection once established in a communication using another mobile terminal as a relay station. In particular, an object of the present invention is to make it difficult to disconnect an established connection even when the number of terminals involved in relaying is large. This makes it possible to adopt this relay technology in an actual mobile communication system.</p><p> In addition, the present invention also balances the right to communicate from outside the communication area and the obligation to provide resources for other terminals, reduces the risk of leakage of communication contents due to relay, and communication. It also aims to suppress traffic and reduce the load on the entire communication system as much as possible.</p>

<p> In the present invention, a mobile terminal equipped with a directional antenna estimates the direction in which radio waves arrive from a nearby terminal, directs the direction in which the sensitivity of the antenna is maximized in a desired direction, and connects to the desired terminal. It features a relay request function to establish.</p><p> It is desirable that the antenna is an adaptive array antenna. Each element constituting the array antenna is preferably a small chip antenna. In particular, the number of elements is preferably four. Further, it is preferable that the array antenna is removable like the attached kit.</p><p> The present invention is characterized in that, when a mobile terminal discovers a plurality of nearby terminals, an appropriate one is selected from them, a connection is established, and communication relay is requested.</p><p> In the present invention, it is preferable to start searching for another terminal that can request relay only when the user tries to start communication. Alternatively, the present invention always searches for another terminal that can request relay and establishes a connection when it is determined that the own terminal is outside the communication area regardless of the presence or absence of the user's communication start request. You can also.</p><p> In the present invention, when a plurality of nearby terminals are found, a terminal that delivers radio waves to its own terminal with the strongest electric field strength is selected as a criterion for selecting an appropriate one from them. Furthermore, even if you select the terminal that delivers radio waves to your terminal with the strongest electric field strength, if you can reach the base station, the terminal that delivers radio waves to your terminal with the second or third strongest electric field strength will be selected. It is desirable to select sequentially.</p><p> Alternatively, as the criterion, a terminal that receives radio waves from the base station with the strongest electric field strength is selected. Furthermore, even if the terminal that receives the radio waves from the base station with the strongest electric field strength is selected, if the terminal can reach the base station, the radio waves from the base station are received with the second and third strongest electric field strengths. It is desirable to select the terminals that are installed in sequence.</p><p> The present invention is characterized in that the maximum number of terminals involved in relay is set in advance. It is desirable that this value can be changed by user setting. It is advisable to set an upper limit on the value that can be set by the user.</p><p> The present invention is characterized in that the number of terminals to be tried to have the strongest electric field strength is set in advance. It is desirable that this value can be changed by user setting. It is advisable to set an upper limit on the value that can be set by the user.</p><p> Alternatively, in the present invention, a terminal in the communication area searches for a terminal in the vicinity and outside the communication area in advance, offers relay, establishes a connection, and the terminal outside the communication area starts communication. The feature is that the communication between the terminal outside the communication area and the base station is relayed.</p><p> In the present invention, a beamforming method or a super-resolution method can be preferably used as an algorithm for estimating the direction in which radio waves arrive. The beamforming method is the most basic and traditional method of estimating the direction of arrival of radio waves based on the Fourier transform method, in which the main lobe (main beam) of a uniform array antenna is scanned in all directions. A method for finding a direction in which the output power of an array increases (for example, Nobuyoshi Kikuma, "Adaptive Signal Processing by Array Antenna", Science and Technology Publishing Co., Ltd., 1999). The super-resolution method is a method based on the conventional beamforming method or Fourier transform, in which the direction of arrival of radio waves is estimated based on eigenvalue analysis in the estimation of the direction of arrival of signals using an array antenna and the identification of radar targets. It is a general term for methods that achieve high resolution beyond the limits. For example, Multiple Signal Classification (MUSIC) method, Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) method, MODE method, etc. can be mentioned. In the present invention, the MUSIC method can be preferably used among the super-resolution methods. The MUSIC method is a method that realizes high-resolution analysis that does not depend on the array length by using the eigenvalues of the correlation matrix of the received data and the orthogonality of the eigenvectors. The analysis is performed based on the analysis.</p><p> It is desirable that the present invention be applied to communication using a spread spectrum method. The spread spectrum method is a method in which a digital signal is spread over a wider band than the original signal by a signal called a spreading code and then transmitted, and the original digital signal is restored by the same spreading code on the receiving side. For example, communication by the Code Division Multiple Access (CDMA) system, the Wideband CDMA (W-CDMA) system, or the CDMA2000 system can be mentioned. The CDMA system is one of the systems used for wireless communication such as mobile phones. It multiplies the audio signals of multiple callers by different codes, synthesizes all the audio signals, and uses one frequency. It refers to the method of sending. As a result, the receiver can extract only the voice signal of the other party by multiplying the composite signal by the code of the other party who is talking with himself / herself. The W-CDMA system is a communication system for third-generation (3G) mobile phones developed by NTT DoCoMo, Inc. and Ericsson. The CDMA2000 system is an international industry group CDMA of telecommunications carriers centered on QUALCOMM. This is a next-generation mobile phone communication method developed by the Development Group (CDG).</p><p> In the present invention, it is desirable that the communication content is encrypted.</p><p> In the present invention, it is desirable that the function of requesting relay from another terminal can be enabled / disabled by the setting of the user or by the contract between the user and the communication carrier. Further, in the present invention, it is desirable that it is possible to switch whether or not to allow the acceptance of the relay requested from another terminal by the setting of the user or by the contract between the user and the communication carrier. Further, it is desirable that the present invention can enable the relay request function to another terminal only when the acceptance of the relay request from another terminal is permitted. Further, the present invention should be configured so that the function of requesting relay from another terminal is effective regardless of the setting for an emergency call such as 110 or in the event of a disaster. Further, in the case of an emergency call or a disaster, the present invention should be configured to always accept a relay request from another terminal regardless of the setting.</p>

<p> According to the present invention, even when the terminal is outside the communication area, it is possible to establish a connection with the base station and perform communication by having another terminal relay the terminal. That is, even if the number of base stations is not increased, the effect is substantially the same as the expansion of the communication area.</p><p> In particular, in the present invention, the mobile terminal is equipped with an antenna that has directivity and can perform adaptive control of the directivity, so that the directivity of the antenna is directed toward the terminal of the relay request destination in the vicinity. By directing the antenna to the null point of the antenna for unnecessary waves, the reception sensitivity from the relay requesting terminal can be optimized. As a result, the terminal of the relay request source can easily establish a connection with the terminal of the relay request destination even in the innumerable unnecessary waves and noise. Moreover, there is an advantage that the connection finally established with the base station is not easily disconnected. This advantage makes it possible for the first time to adopt this technology in a real-life mobile communication system. Since the connection is not easily disconnected, communication traffic increases when trying to establish the connection many times, and the entire communication system is not overloaded.</p><p> The present invention becomes more effective as the number of terminals involved in relaying one connection between a terminal outside the communication area and the base station increases. That is, according to the present invention, it is possible to reliably establish and maintain a connection even when the base station cannot be reached unless a large number of terminals relay. Therefore, the actual communication area can be dramatically expanded without adding a base station at a large cost. For example, even when a base station is damaged by a disaster or the like and a wide area is out of the communication area, the present invention can extend a substantial communication area to the area.</p><p> In addition, with this antenna, the terminal of the relay request destination (as described later, the electric field strength of the radio wave from this terminal is not always sufficiently strong) is selected from among a plurality of nearby terminals based on a certain selection criterion. It is easily possible to select and establish a connection.</p><p> According to the present invention, even if the radio wave arrival direction estimation algorithm is changed, the antenna configuration is not changed, so that the algorithm can be appropriately changed only by changing the software without changing the hardware. There are also advantages.</p><p> According to the present invention, by collecting and analyzing the established connection status on the base station side, the number of terminals existing outside the communication area, their distribution, the quality of radio waves emitted from the base station, their distribution, etc. It is also possible to investigate. Therefore, based on these, an effective database for installing a base station can be constructed.</p>

Embodiments of the present invention will be described with reference to the drawings. &lt;&lt; Example 1 &gt;&gt; FIG. 2 is a schematic view showing the back surface of a mobile phone according to an embodiment of the present invention. FIG. 1 is a conceptual diagram showing the internal configuration of such a mobile phone. This mobile phone includes a radio wave receiving unit 1 (11), an electric field strength monitoring unit 12, a radio wave receiving unit 2 (13), a radio wave arrival direction estimation function unit 14, a terminal search unit 15, and a connection establishment unit 16. , Consists of. The radio wave arrival direction estimation function unit 14 and the terminal search unit 15 cooperate to act as a relay terminal determination unit 17. The radio wave receiving unit 1 (11) is connected to a normal antenna 23 and receives radio waves from a base station. The electric field strength monitoring unit 12 constantly monitors the strength of the electric field input from the radio wave receiving unit 1 (11) at predetermined time intervals. The radio wave receiving unit 2 (13) receives data from a nearby mobile phone by the array antenna 24 composed of the small chip antenna 21. The radio wave arrival direction estimation function unit 14 performs an operation for estimating the radio wave arrival direction on the signal input from the radio wave reception unit 2 (13), and determines the radio wave arrival direction, that is, the direction in which the nearby mobile phone exists. presume. The terminal search unit 15 selects the optimum direction calculated by the radio wave arrival direction estimation function unit 14, and searches for the mobile phone ahead. The connection establishment unit 16 establishes a connection with the mobile phone.

The array antenna 24 in the first embodiment takes the form of a square array in which small chip antennas 21 are arranged in a square shape. Although not shown in FIG. 2, the array antenna 24 is removable like the attached kit.

In the first embodiment, the super-resolution method is used as an algorithm for estimating the radio wave arrival direction by the radio wave arrival direction estimation function unit 14. The super-resolution method is a general term for methods that use eigenvalue analysis for estimating the arrival direction of signals using an array antenna and identifying radar targets. When this method is used, the conventional beamforming method and Fourier transform method are used. High resolution beyond the limit is realized. In particular, in Example 1, the MUSIC method, which is one of the most common super-resolution methods, was used. In this method, a correlation matrix is created from signals incident on each element of the array antenna with a phase shift, and eigenvalue analysis is performed to obtain a signal component and a noise component. Since the eigenvector of the eigenvalue has the property of being orthogonal to the noise vector of the signal, specifically, for example, when the angle is swept from -180 degrees to +180 degrees in 0.1 degree increments, the angle at which the value of the evaluation formula diverges. Is estimated as the direction in which the radio waves arrive. For more information on this, see, for example, Ralph. O. Schmidt), Multiple Emitter Location and Signal Parameter Estimation, I Triple Emitter Location and Signal Parameter Estimation, IEEE Transactions on Antennas and Propagation) (United States), March 1986, vol. AP-34, No. 3, p. 276-280, etc. As a result, in the first embodiment, it is possible to estimate the direction in which the mobile phone in the vicinity exists.

FIG. 3 is a flowchart showing details of the processing performed by the mobile phone of the first embodiment. When the user performs the operation to start communication (S101), the radio wave from the base station is received by the normal antenna 23 owned by the mobile phone (S102), and then the electric field strength at the location of the mobile phone is monitored (S101). S103). Whether or not the radio wave is weak and communication may be interrupted is determined by comparing the electric field strength k (i) with the predetermined threshold value D (S104). When the radio wave is strong and k (i) D, normal communication is possible (S105). When the radio wave is weak and k (i) &lt;D, the arrival direction of the radio wave is estimated by the array antenna 24 in order to search for another mobile phone that relays the communication (S106). It is determined whether or not another mobile phone can be found (S107), and if the other mobile phone cannot be found, communication is disabled (S108). If another mobile phone can be found, since the array antenna of the first embodiment has an adaptive function, select the mobile phone that delivers radio waves to the own terminal with the strongest electric field strength and direct the directivity of the array antenna. , Establish a connection with the mobile phone (S109) and request the mobile phone to relay the communication (S110). At this time, the order i (i = 1 in this case) indicating the number of the mobile phone of the relay request destination counting from the own terminal that is the source of the relay request and the maximum number of terminals n involved in the relay are calculated. , Notify the relay request destination (S110). If the relay request destination responds that communication is possible (S111), communication is possible (S112). If a reply indicating that communication is not possible is obtained (S113), communication is not possible (S114). If no answer is obtained, it is determined whether or not the predetermined time has passed (S115), and if the time-out has occurred, communication is disabled (S116). If it has not timed out yet, it returns to the judgment of whether or not the answer that communication is possible or impossible is obtained again (S111 and S113).

FIG. 4 is a flowchart showing the details of the processing when the mobile phone of the first embodiment is requested to relay the communication from another terminal. When it receives a signal from another mobile phone requesting relay of communication (S201), it receives radio waves through the normal antenna 23 owned by its own terminal (S202), and then the electric field strength at the location of that mobile phone. (S203). Whether or not the radio wave is weak and communication may be interrupted is determined by comparing the electric field strength k (i) with the predetermined threshold value D (S204). If the radio wave is strong and k (i) D, a reply indicating that communication is possible is returned to the relay requester (S205). The radio wave is weak, k (i) &lt; In the case of D, in order to determine whether or not the maximum number of terminals involved in relaying has been reached on the own terminal, the number of the own terminal received from the relay requester is counted from the original mobile phone. The order i and the maximum number of terminals n involved in relay are compared (S206). When the maximum number of terminals has been reached, a reply to the effect that communication is not possible is returned to the relay requester (S207). If the maximum number of terminals has not been reached yet, the direction of arrival of radio waves is estimated by the array antenna 24 in order to search for other mobile phones that further relay communication (S208). It is determined whether or not another mobile phone can be found (S209), and if the other mobile phone cannot be found, a reply to the effect that communication is not possible is returned to the relay requester (S210). If another mobile phone can be found, since the array antenna of Example 1 has an adaptive function, select the mobile phone that delivers radio waves to the own terminal with the strongest electric field strength and direct the directivity of the array antenna. , Establish a connection with the mobile phone (S211) and request processing from the mobile phone (S212). At this time, the number of the order i received from the relay requester, which is the number of the terminal from the original mobile phone, plus 1 (i + 1) (the mobile phone of the relay request destination is large. The order of the number from the original mobile phone) and the maximum number of terminals n involved in the relay are notified to the relay request destination (S212). When a reply indicating that communication is possible is obtained from the relay request destination (S213), a reply indicating that communication is possible is returned to the relay request source (S214). If a reply indicating that communication is not possible is obtained (S215), a reply indicating that communication is not possible is returned to the relay requester (S216). If no answer is obtained, it is determined whether or not a predetermined time has passed (S217), and if a timeout has occurred, a reply indicating that communication is not possible is returned to the relay requester (S218). If it has not timed out yet, it returns to the judgment of whether or not the answer that communication is possible or impossible is obtained again (S213 and S215). Returns (S214). If a reply indicating that communication is not possible is obtained (S215), a reply indicating that communication is not possible is returned to the relay requester (S216). If no answer is obtained, it is determined whether or not a predetermined time has passed (S217), and if a timeout has occurred, a reply indicating that communication is not possible is returned to the relay requester (S218). If it has not timed out yet, it returns to the judgment of whether or not the answer that communication is possible or impossible is obtained again (S213 and S215). Returns (S214). If a reply indicating that communication is not possible is obtained (S215), a reply indicating that communication is not possible is returned to the relay requester (S216). If no answer is obtained, it is determined whether or not a predetermined time has passed (S217), and if a timeout has occurred, a reply indicating that communication is not possible is returned to the relay requester (S218). If it has not timed out yet, it returns to the judgment of whether or not the answer that communication is possible or impossible is obtained again (S213 and S215).

By the above operation, when the user tries to communicate with a mobile phone outside the communication area, the route with the strongest electric field strength is searched from the nearby mobile phone group, the connection is established, and finally eventually. The same processing is performed one after another by the searched mobile phones until communication with the base station can be established via the mobile phones in the communication area of the base station. In this way, communication is possible even with a mobile phone outside the communication area.

FIG. 5 shows a conceptual diagram in the case where a mobile phone outside the communication area tries to communicate in the first embodiment and the base station can be reached by only one mobile phone relaying. In this case, since the primary relay terminal 53 requested to be relayed by the mobile phone 54 outside the communication area is within the communication area 52 of a certain base station 51, the primary relay terminal 53 cannot search for another mobile phone any more. Without having to establish a connection with the base station 51, the mobile phone 54 outside the communication area can start communication.

In addition, Fig. 6 shows a conceptual diagram when two mobile phones can relay and reach the base station. In this case, since the primary relay terminal 64 requested to be relayed by the mobile phone 65 outside the communication area is not in the communication area of any base station, it searches for another mobile phone and finds the secondary relay terminal 63. In this case, since the secondary relay terminal 63 is within the communication area 62 of a certain base station 61, the secondary relay terminal 63 connects with the base station 61 without searching for another mobile phone anymore. The mobile phone 65 outside the communication area can start communication.

In the first embodiment, by adopting the array antenna 24 as the antenna as described above, it is possible to adopt the radio wave arrival direction estimation theory that is still developing.

In the first embodiment, by configuring the array antenna 24 with a small chip antenna 21, the array antenna 24 can be adopted even for the mobile phone 22 which has severe restrictions in terms of mass and size. The background to this is that the frequencies used for communication have become extremely high in recent years. For this reason, it has become possible to adopt a small antenna, and it has become a reality to implement the array antenna 24 even in a portable device called a mobile terminal.

Further, in the first embodiment, by setting the number of elements of the small chip antenna 21 constituting the array antenna 24 to four, the estimation accuracy of the radio wave arrival direction (the larger the number of elements, the better) and the mass of the mobile phone 22. It balances the size, size (generally, smaller ones are better), and cost (lower ones are better). Behind this, the theory of estimating the direction of arrival of radio waves has been greatly developed in recent years, so that even with a relatively small number of elements (for example, four elements as in Example 1), highly accurate estimation can be performed. It can be mentioned that it became.

Further, in the first embodiment, since the array antenna 24 can be attached and detached, the array antenna 24 can be attached in an area where the radio wave is weak, and communication that would otherwise be interrupted can be performed without interruption. In areas where radio waves are strong, the array antenna 24 can be removed to reduce the weight and size of the terminal.

In the first embodiment, the search for another terminal that can request the relay of communication is started only when the user tries to start the communication, thereby suppressing unnecessary search and connection, and the own terminal and the other terminal. We are trying to save power consumption and make effective use of hardware resources.

In the first embodiment, the electric field strength reaching the own terminal is used as a judgment criterion for selecting an appropriate one from a plurality of nearby terminals so that the connection can be reliably established. It is configured.

In the first embodiment, by setting the maximum number n of terminals involved in relaying in advance, the search is repeated infinitely, and the power and hardware resources of other terminals and own terminals are not wasted. It is configured as follows. Furthermore, if this value can be changed by user settings, even if (1) it takes some time to establish a connection, if you really want to communicate, and (2) even if a connection is established. If it takes a long time, the user can use it properly according to the setting depending on whether he / she wants to give up. Furthermore, by setting an upper limit on the value that can be set by the user, it is possible to avoid consuming a large amount of power and hardware resources of another mobile phone for communication of a specific user.

In the first embodiment, a super-resolution method called the MUSIC method is used to realize highly accurate estimation of the direction of arrival of radio waves. If the beamforming method is used as the radio wave arrival direction estimation algorithm, there is an advantage that the amount of calculation is small.

In the first embodiment, communication is performed based on the CDMA system. Since communication based on the spread spectrum system represented by the CDMA system is highly confidential, there is no concern that the communication content will be leaked from the relay terminal, and there is an effect that high security can be maintained. Even if it is not a spread spectrum method, high security can be maintained by encrypting the communication.

In the first embodiment, if the function of requesting the relay of communication from another terminal can be enabled / disabled, the advantage of being able to communicate from outside the communication area and the communication from the terminal that accepts the relay request of communication There is an advantage that the user can measure and select the disadvantage that there is a risk of content leakage. Furthermore, if it is possible to select whether or not to accept the request when the relay is requested from another terminal, the terminal that is requested to relay the communication can use the communication that has nothing to do with the own terminal. Therefore, it is possible to avoid the disadvantage of having to provide hardware resources such as own power and CPU power. Furthermore, if the relay request function for communication to another terminal and the relay request acceptance function from another terminal can only be selected as "both valid" or "both invalid", the specific terminal can communicate with the other terminal. It is possible to avoid enjoying only the right to relay one's own communication to another terminal without fulfilling the obligation of relaying.

Further, in the first embodiment, regardless of the user setting, the relay function is always enabled only in the event of a disaster and for emergency calls such as 110, thereby ensuring the public nature of radio waves and communication systems. can do.

&lt;&lt; Example 2 &gt;&gt; In the first embodiment, after the user performs the operation to start communication (S101 in FIG. 3), it is determined whether or not the user is in the communication area (S104), and only when the user is out of the communication area. , Has started searching for other mobile phones that relay the communication of its own terminal (S106). This method has an advantage that the power consumed by the arrival direction estimation function unit 14 and the like can be saved in that the relay function is used only when necessary. However, on the other hand, in this method, even if the connection with the base station can be finally established, there is a risk that it will take a long time from the time when the user tries to start the communication until the connection is established.

Therefore, unlike the first embodiment, the mobile phone of the second embodiment, which is another embodiment of the present invention, constantly monitors whether or not the own terminal is in the communication area and determines that the terminal is outside the communication area. In the world, even if the user does not try to start the communication, the communication with the base station is established by searching for another mobile phone that relays the communication in advance. As a result, in the second embodiment, when the user tries to start the communication, the communication can be started immediately.

This embodiment will be described with reference to FIGS. 1, 2, and 6. The mobile phone 65 (Fig. 6) constantly monitors the radio waves from the base station 61 (Fig. 6) received by the normal antenna 23 (Fig. 2) using the electric field strength monitoring unit 12 (Fig. 1). When the electric field strength is weakened or when it is completely out of the communication area (for example, mobile phone 61 (Fig. 6)), a small chip type embedded in the back of mobile phone 22 (Fig. 2) The arrival direction of the signal radio wave received from the nearby mobile phone 64 (Fig. 6) by the array antenna 24 (Fig. 2) consisting of the antenna 21 (Fig. 2) using the radio wave arrival direction estimation function unit 14 (Fig. 1). And estimate the direction of nearby mobile phones 64 (Fig. 6). Then, the connection establishment unit 16 (Fig. 1) is used to establish a connection with the mobile phone 64 (Fig. 6), and when the terminal is also outside the communication area, the mobile phone 64 (Fig. 6) is established. Perform the same process in 6). Finally, if the mobile phone 63 (Fig. 6) in the communication area 62 (Fig. 6) of the base station 61 (Fig. 6) can be reached, even the mobile phone 65 (Fig. 6) outside the communication area can reach the communication area. A connection with the base station 61 (Fig. 6) can be established via the mobile phone 63 (Fig. 6) in 62 (Fig. 6), and communication becomes possible.

The process performed by the mobile phone of the second embodiment differs from the process performed by the mobile phone of the first embodiment (FIG. 3) not only when the user performs a communication start operation, but is always shown in FIG. It is to carry out the processed processing.

In the second embodiment, if it is determined that the own terminal is outside the communication area regardless of whether or not the user has requested to start communication, another terminal that can request relay is searched for and a connection is established. Therefore, when the user tries to start the communication, the communication can be started immediately without waiting for the user.

&lt;&lt; Example 3 &gt;&gt; In the mobile phone of Example 1, either the case where the own terminal is the base (Fig. 3) or the case where the relay is requested from another mobile phone (Fig. 4). However, when multiple mobile phones can be found in the vicinity, select the mobile phone that delivers radio waves to your terminal with the strongest electric field strength and establish a connection with that mobile phone (S109 and S211). ), Requesting relay from the mobile phone (S110 and S212). However, when such a relay terminal search algorithm is used, the mobile phone that delivers the radio wave to the own terminal with the strongest electric field strength is not always physically close to the base station. Therefore, even if communication is finally possible, there is a fear that the processes shown in Fig. 3 and Fig. 4 will not converge easily and it will take time to start communication, and power and hardware resources will be wasted. There is. Also, although it depends on the value of the maximum number of terminals n involved in relaying, although it should be possible to reach a base station if the route is selected properly, in reality it is not possible to reach any base station and communication is not possible. There is a fear of becoming.

Therefore, when the mobile phone of the third embodiment, which is another embodiment of the present invention, can find a plurality of mobile phones in the vicinity, the array antenna of the present embodiment has an adaptive function, and therefore, from the base station. Select the mobile phone that receives the radio waves of the strongest electric field strength, direct the array antenna, establish a connection with the mobile phone (S109 and S211), and request the mobile phone to relay (S110 and S212).

The processing performed by the mobile phone of the third embodiment differs from the processing performed by the mobile phone of the first embodiment, which is a mobile phone that establishes a connection to request a relay when a plurality of mobile phones can be found. (S109 and S211), select a mobile phone that receives radio waves from a base station with the strongest electric wave strength, not a mobile phone that delivers radio waves to its own terminal with the strongest electric wave strength. To do this, first establish a connection with some or all of the multiple mobile phones found in the vicinity, and then ask each mobile phone how strong each is receiving radio waves from the base station. .. By referring to the answers from each mobile phone to this inquiry, the mobile phone that receives the radio waves from the base station with the strongest electric field strength may be selected.

A mobile phone that receives radio waves from a base station with the strongest electric field strength is likely to be physically close to the base station. By repeating with, it is possible to gradually approach the base station, and there is a high probability that the base station will be reached in the end.

&lt;&lt; Example 4 &gt;&gt; In Example 1, if the base station cannot be reached within the range of the maximum number of terminals n involved in relaying, communication is disabled there. On the other hand, in the mobile phone of Example 4, which is another embodiment of the present invention, when a plurality of mobile phones can be found in the vicinity, communication is not disabled there, and the second of them is the own terminal. -Select the mobile phones that deliver radio waves with the third strongest electric field strength in sequence, establish a connection with the mobile phones (S109 and S211), and request the mobile phones to relay (S110 and S212). As a result, even if the tip of the mobile phone that delivers the radio wave to the own terminal with the strongest electric field strength is a dead end, there is a possibility that the base station can be finally reached.

Here, it is desirable that the number of mobile phones with the strongest electric field strength to be tried is set in advance. As a result, it is possible to prevent the search from being repeated indefinitely when there are innumerable mobile phones in the vicinity such as during congestion. It is desirable that the limit of the number of trials for the mobile phone with the strongest electric field strength can be changed by the user setting.

In the fourth embodiment, when the base station is reached by selecting the terminal having the strongest electric field strength reaching the own terminal, a relay request is made to the terminal having the second or third electric field strength reaching the own terminal. By trying, we are avoiding the situation where we should be able to reach the base station if we choose the route well, but we cannot actually reach any base station and communication is not possible. In this embodiment, since the adaptive array antenna is adopted, it is certain that not only the relay terminal having the strongest electric field strength reaching the own terminal but also the second and third strongest terminals are selected. You can establish a connection to.

&lt;&lt; Example 5 &gt;&gt; In the first embodiment, the mobile phone 54 (Fig. 5) outside the communication area requests relay from the nearby mobile phone 53 (Fig. 5), and finally the base station 51 (Fig. 5). ) Has been established. On the other hand, in the fifth embodiment, the mobile phone 53 (FIG. 5) in the communication area searches for the mobile phone 54 (FIG. 5) in the vicinity and outside the communication area in advance, and becomes the base station 51 (FIG. 5). By offering to relay the above, a connection with the mobile phone 54 (Fig. 5) and the base station 51 (Fig. 5) outside the communication area is established. Therefore, when a user of the mobile phone 54 (FIG. 5) outside the communication area tries to start the communication, the communication can be performed immediately.

In this way, in the fifth embodiment, it is possible to efficiently find a terminal on which the mobile phone 54 (FIG. 5) outside the communication area relays its own communication. Further, when the mobile phone 54 (Fig. 5) outside the communication area tries to start the communication, the communication can be performed immediately.

In the embodiments described so far, examples in which the present invention is applied to a mobile phone have been described, but the application of the present invention is not limited to this. The present invention is applicable not only to mobile phones but also to any mobile communication system including mobile phones, car phones, mobile terminals, mobile terminals, mobile terminals, etc., regardless of the name and form. can do.

When multiple terminals in the vicinity are found, the criteria for selecting an appropriate one from them are the two types described in the above embodiment (the terminal that delivers radio waves to its own terminal with the strongest electric field strength). It is not limited to selecting and selecting the terminal that receives the radio waves from the base station with the strongest electric field strength). For example, the number of terminals involved in relaying based on a certain evaluation function based on the electric field strength of radio waves reaching the own terminal from each nearby terminal and the electric field strength of radio waves from a base station received by each nearby terminal. It is also possible to select a device that has a relatively small number of radio waves and is presumed to have a relatively reliable connection with the base station.

Although each element constituting the array antenna is arranged in a square shape in the first embodiment (Fig. 2), various other arrangements such as a circular shape and a linear shape are possible.

In the first embodiment, the MUSIC method is adopted as an algorithm for estimating the direction of arrival of radio waves, but various other methods can be used. For example, an algorithm that adds calibration processing to the MUSIC method is currently being developed (for example, Takahiro Arai and three others, "Super Resolution Array Calibration Method Using Known Wave Sources", Institute of Electronics, Information and Communication Engineers. Journal (B), March 2003, vol. J86-B, no. 3, p. 527-535). By using such a method, it is possible to perform more accurate and reliable estimation even in an actual antenna in which couplings and characteristic errors exist between each element of the array antenna.

In the first embodiment, the CDMA system is adopted as the spread spectrum system, but other W-CDMA system, CDMA2000 system, etc. can be adopted without any trouble.

<figref num="1">It is a figure which shows the structure of the mobile terminal which is an example which carried out this invention.</figref><figref num="2">It is a figure which shows the array antenna of the mobile terminal which is an example which carried out this invention. Small chip antennas are arranged in a circle.</figref><figref num="3">It is a flowchart which shows the process which performs when the mobile terminal which is the example of carrying out this invention starts communication.</figref><figref num="4">It is a flowchart which shows the process to perform when the mobile terminal which is the example which carried out this invention is requested to relay.</figref><figref num="5">It is a conceptual diagram which shows the state of communication of a mobile terminal and a base station when one terminal can reach a base station only by relaying in the mobile communication system which is an example of carrying out this invention.</figref><figref num="6">It is a conceptual diagram which shows the state of communication of a mobile terminal and a base station when two terminals can relay and reach a base station in the mobile communication system which is an example of carrying out this invention.</figref><figref num="7">It is a conceptual diagram which shows the state of communication of the mobile communication system by a prior art.</figref>

Code description

11 Radio receiver 1 (normal antenna) 12 Electric field strength monitoring unit 13 Radio receiver 2 (array antenna) 14 Arrival direction estimation function 15 Terminal search 16 Connection establishment 17 Relay terminal determination 21 Small chip antenna 22 Mobile phone (Viewed from the back) 23 Normal antenna 24 Array antenna 51 Base station 52 Base station communication area 53 Mobile phone inside the base station communication area 54 Mobile phone outside the communication area 61 Base station 62 Base station communication area 63 Mobile phones in the communication area of the base station 64 Mobile phones outside the communication area 65 Mobile phones outside the communication area 71 Base station A 72 Communication area of base station A 73 Mobile phones in the communication area of base station A 74 Base station B 75 Communication area of base station B 76 Mobile phone in communication area of base station B 77 Mobile phone outside communication area 78 Mobile phone outside communication area