JP2006013811A - Information terminal equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information terminal device capable of efficiently broadcasting and receiving contents by efficiently switching communication modes.
SOLUTION: The present invention measures the moving speed of an information terminal device, and determines whether to use one communication mode of an ad hoc mode using an ad hoc network or an infrastructure mode using a public network based on the measured moving speed. By receiving or transmitting information using the determined communication mode, it is possible to efficiently broadcast and receive content.
[Selection] Figure 1

Description

  The present invention relates to an information terminal device that can efficiently broadcast and receive content.

  A network that is dynamically formed between wireless terminals without using an infrastructure such as a base station is called a wireless ad hoc network (hereinafter simply referred to as an ad hoc network). In an ad hoc network, when a wireless terminal cannot communicate directly, a wide range of networks can be handled by relaying other terminals. Ad hoc networks can be built even when the existing infrastructure cannot be used, so applications for conferences and disasters are being considered.

  In order to distribute content from a specific server or to collect information from a terminal efficiently using an ad hoc network, the ad hoc mode using the ad hoc network and the infrastructure mode using the public network are used for content distribution. A smooth switching function of the communication mode to be switched is required. As a method for automatically switching communication modes and realizing wireless communication, for example, there is a method described in Patent Document 1.

In the method of Patent Document 1, communication is attempted in the infrastructure mode. When the infrastructure mode is usable, the terminal is set so that the infrastructure mode can be used. When the infrastructure mode cannot be used, the ad hoc mode is selected. Build a network.
Japanese Patent Application No. 2001-131335, wireless communication device

  However, in the conventional method, once the communication mode is determined, the communication mode is not changed. For this reason, when a terminal moves during communication in infrastructure mode and communication becomes impossible in infrastructure mode, the problem that content distribution cannot be performed arises.

  Also, in order to follow changes in the network (areas where communication is possible in infrastructure mode and areas where communication is not possible), there is a method of always checking the communication mode that can be used. In order to investigate, it is necessary to always detect available communication modes. The detection of the communication mode has a problem that a great processing load is applied and power consumption and communication of the terminal are affected.

  The present invention has been made in view of this point, and an object of the present invention is to provide an information terminal device that can efficiently broadcast and receive content by switching communication modes efficiently.

  The present invention measures the moving speed of the information terminal device, determines whether to use one of the communication modes of the ad hoc mode using the ad hoc network or the infrastructure mode using the public network based on the measured moving speed. Information was received or transmitted using the communication mode.

  According to the present invention, by using a trigger that can be easily measured, that is, a moving speed, the communication mode can be switched efficiently, and content broadcasting and reception can be performed efficiently.

  The information terminal device according to the first aspect of the present invention includes a moving speed measuring means for measuring a moving speed and one communication in an ad hoc mode using an ad hoc network or an infrastructure mode using a public network based on the measured moving speed. A communication mode determination unit that determines whether to use a mode and a communication control unit that communicates information using the determined communication mode are employed.

  Thus, by using the movement speed as a trigger for switching the communication mode, the communication mode can be appropriately switched by a light process of detecting the movement speed. This eliminates the need for heavy processing to constantly check available communication modes in order to switch communication modes following changes in the network.

  According to a second aspect of the present invention, in the information terminal device according to the first aspect, the information terminal device further includes a movement direction detection unit that detects a movement direction, and the communication mode determination unit selects a communication mode based on a change in the movement direction. Switch.

  If a large change occurs in the moving direction, the moving speed is greatly reduced. Therefore, the communication mode can be changed according to the moving speed by changing the communication mode by changing the moving direction.

  According to a third aspect of the present invention, in the information terminal device according to the first aspect, the processing load of the information terminal device of the communication partner, the remaining power of the information terminal device, the link delay with the information terminal device, The information terminal device according to claim 1, wherein the communication mode is switched based on at least one of a connection time with the information terminal device, importance of the information, and electric field strength in the information terminal device.

  Thereby, the processing load of the information terminal device of the communication partner, the remaining power of the information terminal device, the link delay with the information terminal device, the connection time with the information terminal device, the importance of the information, the information terminal device The communication mode to be selected can be determined in consideration of the electric field strength at.

  According to a fourth aspect of the present invention, in the information terminal device according to any one of the first to third aspects, the information is index information indicating the content.

  As a result, since the ad hoc mode has a slower communication speed than the infrastructure mode, it is possible to prevent the processing load of the ad hoc network from becoming too large by distributing information with a relatively small amount of data such as index information.

  According to a fifth aspect of the present invention, in the information terminal device according to any one of the first to fourth aspects, the transmission for calculating the transmission interval of the information based on at least one of the transmission time or version of the information An interval calculation unit is provided, and the communication control unit transmits information at the transmission interval.

  Thereby, transmission of redundant information can be suppressed.

  According to a sixth aspect of the present invention, in the information terminal device according to any one of the first to fifth aspects, at least one of the movement speed, the processing load, the remaining power, and the importance of the information to be transmitted. Transmission interval calculation means for calculating the transmission interval of the information based on one or more information is provided, and the communication control means transmits information at the transmission interval.

  As a result, it is possible to estimate the long-term stability of communication and distribute necessary content at an appropriate timing.

  A seventh aspect of the present invention includes a service device that manages and distributes information, a terminal device that relays the information, an information reception device according to the first aspect, an ad hoc network, and a public network. The information receiving device receives the information distributed from the service device via the public network, and receives the information relayed from the terminal device via the ad hoc network. It is a network system.

  According to an eighth aspect of the present invention, in the ad hoc network system according to the seventh aspect, when the information is changed, the service device distributes only the changed difference.

  As a result, only the updated difference information needs to be transmitted, so that it is not necessary to transmit the index information portion that is not necessary for updating to the terminal device, and the index information can be updated efficiently.

  The information terminal device of the present invention focuses on the fact that it is not preferable to use the ad hoc mode when the moving speed is high, and it is preferable to use the infrastructure mode when the moving speed is low. The moving speed is used as a trigger for performing the above. As a result, the communication mode can be appropriately switched by a light process of measuring the moving speed.

(Embodiment 1)
Hereinafter, an information terminal device according to Embodiment 1 of the present invention will be described in detail with reference to the accompanying drawings. First, an ad hoc network system including the information terminal device according to the first embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of an ad hoc network system according to the first embodiment.

  The ad hoc network system 100 according to the first embodiment includes a terminal device 101 that is a mobile terminal that has a communication control function and functions as an information transmission / reception device, and a terminal device 102a that is a mobile terminal having a communication function using ad hoc. , 102b are connected via an ad hoc network 103. The terminal device 101 is connected to a service device 104 having a server 105 having contents and index information via a public network 106. As described above, the terminal device 101, which is a feature of the first embodiment, has two communication modes, an ad hoc mode that is communication using the ad hoc network 103 and an infrastructure mode that is communication using the public network 106.

  Next, the configuration of the terminal device 101 will be described in detail.

  The terminal device 101 is provided with a terminal control unit 114 that controls each processing unit. The terminal control unit 114 is a control unit such as a CPU.

  The terminal device 101 also includes a terminal density measuring unit 107, a moving speed measuring unit 108, a communication mode determining unit 109, a transmission interval calculating unit 110, and a communication control unit 111 that controls and manages these as communication means. And are provided.

  The terminal density measuring unit 107 identifies transmission packets from the other terminal apparatuses 102a and 102b and determines whether the other terminal apparatuses 102a and 102b are present in a large or small amount.

  The moving speed measurement unit 108 measures the moving speed and the moving direction of the terminal device 101 using a sensor such as a GPS or a gyro.

  The communication mode determination unit 109 employs either an infrastructure mode that realizes connection with a public network or a wired network such as a wireless LAN, or an ad hoc mode that realizes ad hoc communication between terminals without using a base station. To determine.

  The transmission interval calculation unit 110 calculates the transmission interval of index information indicating the content and the location of the content.

  Further, the terminal device 101 is provided with a storage management unit 112 that performs storage management of index information and content, and an index information management unit 113 that manages index information. The accumulation management unit 112 is assumed to be an SD memory card, a hard disk, or the like.

  With this configuration, the terminal device 101 can acquire index information indicating content, content type (genre, audience, etc.) and location from the service device 104. In the present invention, the content includes multimedia information such as video, audio, still image, and text, and control information such as layout.

  The terminal device 101 can simultaneously use a plurality of communication / broadcast media such as a wireless network such as a wireless LAN, Bluetooth, and a mobile phone, a wired network such as ADSL and ISDN, digital broadcasting, and satellite broadcasting as a communication means. It is good. In addition, in the wireless network, the terminal device 101 can configure the ad hoc network 103 on at least one wireless medium.

  Next, the index information will be described with reference to FIG. FIG. 2 is a diagram for explaining index information according to the first embodiment.

  In the index information 200, a creator name 201, a creation date 202, and a version 203 are described as information for identifying the index information. The index information 200 includes content name 204, title 205, summary 206, latitude / longitude 207, which is position information corresponding to the content, URL 208 indicating the location of the content, and content as information indicating the content. A plurality of sets of size 209 are described.

  The terminal device 101 can acquire the index information 200 from a communication network, a broadcast network, and a storage medium. The terminal device 101 manages the acquired index information by the index information management unit 113 and is mainly used for acquiring content in advance from the service device 104 based on the index information.

  Next, an operation in which the terminal device 101 acquires content from the service device 104 based on the index information will be described with reference to FIG. FIG. 3 is a diagram illustrating an operation in which the terminal device 101 according to the first embodiment acquires content in advance.

  3 indicates the current position of the terminal device 101, and ○ (302) indicates the position corresponding to the latitude / longitude 207 of the content, which is an area surrounded by a dotted line. Reference numeral 303 denotes a target area from which the terminal device 101 acquires content.

  The size and shape of the pre-acquisition area are determined based on the amount of movement of the terminal device 101. In the example of FIG. 3, the terminal device 101 has an area for pre-acquisition of content as an ellipse having the moving direction as a major axis.

  The content acquisition area determination processing method is described in detail in Sato et al. “Broadcasting / communication-linked mobile content distribution method”, Information Processing Society of Japan MBL Study Group (2003).

  First, the terminal device 101 measures the current location 301 and the moving direction in the moving speed measuring unit 108. Next, the communication control unit 111 of the terminal device 101 determines the region 303 in consideration of the location 301 of the terminal device 101 and the moving direction, that is, the region where the terminal device 101 may move from now on. Next, the communication control unit 111 of the terminal device 101 acquires content having the location 302 in the area 303 via the communication network.

  In this way, the terminal device 101 acquires and displays the content in advance before passing the vicinity of the location 302 of the content.

  Next, the communication mode switching process of the terminal device 101 will be described with reference to FIG. FIG. 4 is a flowchart regarding the communication mode switching process of the terminal device 101 according to the first embodiment.

  First, the terminal device 101 acquires the moving speed of the terminal device 101 in the moving speed measuring unit 108. Next, the communication mode determination unit 109 of the terminal device 101 acquires the movement speed from the movement speed measurement unit 108 via the communication control unit 111 (step 401).

  Next, the communication mode determination unit 109 determines whether or not the traveling speed acquired in step 401 is equal to or higher than the specified speed and is continuously running for a predetermined time (step 402).

  If it is determined in step 402 that the vehicle is continuously traveling at a specified speed or lower, the communication mode determination unit 109 determines that communication is possible in the infrastructure mode because the moving speed is low and communication with the base station is possible in this state. . Then, the communication control unit 111 starts communication by switching the communication mode to the infrastructure mode (step 403).

  On the other hand, if it is determined in step 402 that the vehicle is continuously traveling at the specified speed or higher, the communication mode determination unit 109 determines that this state is high in movement speed and difficult to communicate with the base station, and is in ad hoc mode. Is determined to be preferable. And the communication control part 111 switches communication mode to ad hoc mode, and starts communication (step 404).

  By introducing this communication mode switching method, an appropriate communication mode can be appropriately selected in accordance with the moving speed of the terminal device 101. As a result, it is possible to avoid a situation in which the communication mode is not changed once the communication mode is determined as in the prior art.

  Further, by using the movement speed as a trigger for switching the communication mode, the communication mode can be switched by a light process of detecting the movement speed. This eliminates the need for heavy processing to constantly check available communication modes in order to switch communication modes following changes in the network.

  Note that switching from the infrastructure mode to the ad hoc mode may also be performed when the line quality deteriorates during communication in the infrastructure mode or when another terminal device capable of communicating in the ad hoc mode is found.

  Furthermore, not only the moving speed of the terminal device 101 but also the moving direction may be taken into account as a trigger for switching the communication mode. This is because, generally, if a large change occurs in the moving direction of the terminal device 101, the moving speed of the terminal device 101 is greatly reduced. Therefore, the communication mode can be changed according to the moving speed by changing the communication mode by changing the moving direction. Note that the movement direction of the terminal device 101 can be detected by using a gyro.

  In addition, by limiting the detection of usable communication modes (ad hoc mode or infrastructure mode) to the timing when the moving direction has changed significantly, the power consumption of the terminal can be reduced or Less communication is possible.

  In addition to the moving speed of the other terminal device 102, the terminal device 101 has a processing load of the other terminal device 102, a remaining power of the other terminal device 102, a link delay with the other terminal device 102, another terminal The communication mode to be selected may be determined in consideration of parameters such as the connection time with the device 102, the importance of information to be transmitted, and the electric field strength in other terminal devices 102.

  For example, when the processing load of the other terminal apparatus 102 is heavy, the communication mode is set so that the public network is used in order to avoid deterioration of transmission quality (loss, delay, jitter) due to a delay of relay processing due to the processing load of the other terminal. Select. Conversely, when the processing load is small, an ad hoc communication mode with a low communication cost is selected. Note that when the storage capacity is small or the number of connections from other terminals is large, the processing load on the terminal increases, so the communication mode is selected so that the public network is used in the same manner. These two parameters may be used alone or in combination.

  In addition, when the remaining power of the other terminal apparatus 102 is small, it is necessary to secure a highly reliable communication path, so the communication mode is selected to use the public network. Conversely, when the remaining power is large, an ad hoc communication mode with a low communication cost is selected. Similarly, a terminal with a short total processing time or start-up time has a small track record as a relay terminal in an ad hoc network, so it is necessary to secure a highly reliable communication path, and a communication mode is set to use a public network. select.

  If the link delay with the other terminal apparatus 102 is large, it is determined that the traffic of the ad hoc network is increasing / doing, and the communication mode is selected to use the public network. Conversely, when the link delay is small, an ad hoc communication mode with a low communication cost is selected. Similarly, instead of link delay, the transmission band is a quality characteristic of the transmission path (the traffic is judged to increase / decrease if the available transmission band is small), and the loss rate (the traffic increases if the loss rate is high). ) And hop count (determined that traffic is increased / decreased if the hop count is high) may be used singly or in combination.

  If the connection time with the other terminal apparatus 102 is long, it is determined that the communication path of ad hoc communication is stable, and an ad hoc communication mode with a low communication cost is selected. Conversely, when the connection time is short, a public network with a stable communication path is used.

  If the information you want to send is of high importance, ad hoc communication is worse in data reachability, quality (delay, jitter), and security than the public network, so select the public network mode for information of high importance. To send. Information with low importance is transmitted by selecting an ad hoc mode with a low communication cost.

  Further, when the electric field strength in the other terminal apparatus 102 is strong, it is estimated that there is a terminal capable of performing inter-terminal communication in the vicinity of the own terminal, and it is determined that ad hoc communication between the terminals is possible. Select the communication mode by. On the other hand, when the electric field strength in the other terminal apparatus 102 is weak, it is determined that there is no terminal that can communicate between the terminals in the vicinity of the own terminal, and communication is performed via the public network. An error rate of the transmission line may be used instead of the electric field strength. If the error rate is high, it is determined that communication between terminals is difficult, and a public network is selected. Note that the electric field strength and the error rate may be used in combination.

  The effect of using ad hoc communication is described in terms of low communication costs. However, when the ad hoc network communication band is secured, information can be transmitted with a lower delay than the public network. There is.

  Next, relay processing of the ad hoc network system 100 according to the first embodiment will be described.

  In the ad hoc network system 100, each terminal device 101, 102a, 102b can be a transmission terminal or a reception terminal. For this reason, there is a possibility that each terminal device 101, 102a, 102b may send information without permission and cause a traffic failure.

  Therefore, in the ad hoc network system 100, it is possible to suppress a traffic failure by specifying terminal devices that can be transmitted by the terminal devices 101, 102a, and 102b. Here, the identified terminal device is called a relay terminal. As a method for specifying a relay terminal, the following two methods are roughly considered.

  Relay terminal determination method 1: a method in which the terminal device 101 that has received the index information or content received from the service device 104 becomes the first relay terminal and selects the second relay terminal (the current relay terminal is the next relay terminal) A method for nominating a relay terminal).

  Relay terminal determination method 2: A method in which the terminal devices 101 and 102 themselves apply to become relay terminals and become relay terminals.

  For example, when none of the terminal devices 101 and 102 has applied for a relay terminal within a predetermined time, the terminal devices 101 and 102 that have applied for a relay terminal become a relay terminal. Note that if any of the terminal devices 101 and 102 is calling that it is a relay terminal, the terminal devices 101 and 102 that have applied to become a relay terminal later cannot be a relay terminal.

  Next, the relay terminal determination method 1 of the ad hoc network system 100 will be described with reference to FIG. FIG. 5 is a flowchart of the relay terminal selection process of the terminal device 101 according to the first embodiment.

  In the ad hoc network system 100, each terminal device 101, 102 broadcasts or multicasts the state parameters of each terminal device 101, 102 to other terminal devices 101, 102 periodically or based on a transmission interval described below. is doing. The state parameters include latitude / longitude indicating the current positions of the terminal devices 101 and 102, the moving speed of the terminal, the moving direction, the load, and the remaining power.

  First, the terminal device 101, which is the first relay terminal that has obtained the index information from the server and that wants to distribute index information and content, determines the other terminal in the communication control unit 111 from the state parameter transmitted by the other terminal device 102. The moving speed of the apparatus 102 is observed (step 501).

  Next, in the terminal device 101, the communication control unit 111 proceeds to the relay terminal extraction process (step 502). In this example, the moving speed is a selection condition. This is because the terminal device 102 having a high moving speed may move far in the middle of communication, and communication may be interrupted.

  And the communication control part 111 judges whether the moving speed of the other terminal device 102 is more than a threshold value (step 503). As for the threshold, for example, the moving speed of the terminal is set to 30 km / h.

  Next, in Step 503, the communication control unit 111 selects one of the other terminal devices 102 whose moving speed is lower than the threshold as a relay terminal (Step 504). On the other hand, the communication control unit 111 does not select the terminal device 102 whose moving speed is higher than the threshold as a relay terminal (step 505).

  As described above, the terminal device 101 can extract the terminal device 102 that can be relayed safely by detecting the moving speed of the other terminal device 102 and relay information.

  In addition to the moving speed of the other terminal device 102, the terminal device 101 moves in the other terminal device 102 moving direction, the processing load of the other terminal device 102, the remaining power of the other terminal device 102, and the other terminal device 102. The terminal to be relayed is determined in consideration of parameters such as link delay with the other terminal device 102, connection time with the other terminal device 102, importance of information to be transmitted, electric field strength in the other terminal device 102 and error rate of the transmission path. May be.

  For example, when the terminal device 101 selects a relay terminal, index information and content can be distributed further by taking into account the current position of the other terminal device 102.

  In addition, when the terminal device 101 selects a relay terminal, the terminal device 102 that is far from itself without considering the terminal device 102 that is approaching itself as a relay terminal candidate, considering the moving speed and the moving direction. 102 may be a relay terminal candidate. Thereby, it can be expected that the index information can be distributed over a wide range from the terminal device 101.

  In addition, the terminal device 101 may be preferentially selected as a relay terminal on the assumption that the terminal device 102 having a low moving speed, a low terminal load, and a long connection time has high stability when performing communication. .

  In addition, regarding relaying information with high importance, the terminal device 101 may prioritize quick relaying of information, and may select the terminal device 102 whose moving speed is higher than a threshold as a relay terminal. Here, information with high importance can include information with high urgency, information with high update degree, difference information, and the like.

  Further, when the terminal device 101 selects a relay terminal, for example, taking into account the total processing time such as the connection time with the other terminal device 102 and the elapsed time since the other terminal device 102 started to start. Also good. For example, when the other terminal device 102 is a portable terminal, if the above-described elapsed time is short, it indicates that the user is turning on / off the terminal power. For this reason, the terminal device 101 determines that the terminal device 102 whose elapsed time is shorter than the predetermined time is not a terminal device that can stably relay, and removes it from the relay device candidates. Note that the connection time with the other terminal device 102 is calculated as the total connection time from the actual number of times the packet has been received from the other terminal device 102 in the past and the generation time and period.

  The terminal device 101 can measure the link delay with the other terminal devices 102 by the transmission delay of packets exchanged by routing and the transmission delay of the status information of each terminal that is periodically transmitted. is there. Similarly, it is determined that the transmission band, which is the quality characteristic of the transmission path (the traffic is increased / decreased if the available transmission band is small), and the loss rate (the traffic is increased / increased if the loss rate is high). ), The number of hops (when the number of hops is high, it is determined that traffic increases / is) can be observed in the same manner, and as with link delay, it can be used as a guideline when selecting a relay terminal, May be used in combination.

  Next, the relay terminal determination method 2 of the ad hoc network system 100 will be described.

  The terminal device 101 determines whether the communication control unit 111 is a terminal to be relayed based on at least one or more information among the moving speed, load, remaining power, and importance of information to be transmitted. decide.

  For example, the communication control unit 111 of the terminal device 101 refrains from becoming a relay terminal because it may move out of the relay range during the relay process when its own moving speed is high. Further, the communication control unit 111 of the terminal device 101 refrains from becoming a relay terminal because the relay processing is hindered if the terminal load is large. Further, the communication control unit 111 of the terminal device 101 refrains from becoming a relay terminal because there is a possibility that the power may be lost during the information relay process even when the remaining power of the terminal is small.

  However, the terminal device 101 may transmit the index information and the content even if these conditions are satisfied when it is desired to transmit information with high importance.

  In this way, by performing relay processing in consideration of the moving speed, moving direction, content type, and the like of the terminal devices 101 and 102, the terminal devices 101 and 102 suitable for distributing content over a wide area are used as relay terminals. You can choose.

  Next, when the terminal device 101 distributes index information or content, or when the terminal device 101 is in a state of another terminal device 102 (latitude / longitude indicating the current position of the terminal, moving speed of the terminal, moving direction, load, The transmission interval when transmitting the (remaining power) parameter will be described. By adjusting the transmission interval, it is possible to suppress the transmission of a large amount of traffic, and thus it is possible to suppress a traffic failure.

  Next, the transmission interval determination process of the terminal device 101 will be described in detail with reference to FIG. FIG. 6 is a flowchart of the transmission interval determination process of the terminal device 101 according to the first embodiment.

  The terminal device 101 receives the transmission time and version of the index information transmitted from the other terminal device 102 in the communication control unit 111, and observes the transmission time and version of the index information in the terminal density measurement unit 107 (step) 601).

  Specifically, in the index information, the type that can identify the genre of information and the transmission time and version at which transmission of index information is first started are described, and the terminal density measuring unit 107 observes the index information. Thus, the type, transmission time, and version that can identify the genre of information are observed.

  In addition, the terminal density measuring unit 107 compares the index information held by the other terminal device 102 with the index information held by the own terminal device 101 and estimates how much the information overlaps. Also, the terminal density measuring unit 107 arranges the received index information for each type that can identify the genre of information in time series in the order received.

  In addition, the attribute (gender, age, etc.) regarding the genre of the provided information and the recipient is added to the index information, and the terminal device 101 stores the attribute based on the genre and the recipient's attribute given on the terminal side. Index information to be managed may be selected.

  Next, the transmission interval calculation unit 110 determines a transmission interval when index information and content are transmitted by the terminal itself from the observation result of the terminal density measurement unit 107 (step 602).

  Specifically, the transmission interval calculation unit 110, when many pieces of index information with old transmission times or old versions are transmitted from other terminals, the other terminals 102 already hold similar index information. And increase the transmission interval. On the other hand, when a transmission time or a new version is transmitted without much overlap, the transmission interval calculation unit 110 determines that the index information is not distributed to other terminals 102. In order to speed up distribution to other terminals 102, the transmission interval is shortened. With this method, transmission of redundant index information can be suppressed.

  The terminal device 101 calculates an information transmission interval based on at least one or more information among the moving speed of the own terminal, the load of the own terminal, the remaining power of the own terminal, and the importance of the information to be transmitted. You may go.

  For example, when the moving speed of the terminal device 101 is fast, it can be expected that distribution to a wide range can be realized in a short time by shortening the transmission interval. Further, when the load on the terminal device 101 is high and the remaining power is small, the transmission interval is lengthened.

  Note that information with high importance is information with high urgency, information with high degree of update, difference information, and the like. For example, the terminal device 101 increases the transmission interval for highly urgent information. Specifically, the terminal device 101 determines the reference for calculating the transmission interval based on the reception time of the received index information, and the received index information is 1 second and 1 minute after the reception time.

  In this way, the terminal device 101 estimates the long-term stability of communication by considering various parameters such as load, link delay, terminal power, and terminal electric field strength, and obtains necessary content at an appropriate timing. Can be delivered and received.

  As described above, according to the first embodiment, the total processing time in the terminal device, the moving speed of the terminal device, the moving direction, and the type of content to be distributed are parameters that are not particularly considered in the moving object. In consideration of this, it is possible to appropriately determine the switching between the public network and the ad hoc, the determination method of the relay terminal, and the determination method of the transmission interval.

  In addition, by limiting the detection of available communication modes (ad hoc mode or public network) to the timing at which the movement speed has greatly changed, the power consumption of the terminal can be reduced or Less communication is possible.

  In the present invention, the switching method between the public network and the ad hoc, the determination method of the relay terminal, the determination method of the transmission interval, and the like have been described. In any processing, the state of the transmission path (bandwidth, loss rate, transmission delay, hops) Number, electric field strength, transmission path error rate), terminal status (terminal load, remaining power, storage capacity, number of connections from other terminals, total processing time, startup time), terminal location (terminal location ( Parameters such as latitude / longitude), moving speed, moving direction), and preference (genre or keyword preferred by an individual) may be used. The startup time refers to the time from when the terminal starts operating until the present time. In the case of a portable terminal, since it is assumed that the user turns on or off the terminal as necessary, the activation time is considered to be an effective factor. Also, when the storage capacity is low or the number of connections from other terminals is large, it can be expressed as a factor that increases the processing load on the terminal, so it can be used as a method for specifically measuring the load on the terminal. it can. In addition, generally, if the electric field strength is weak, transmission errors increase. Therefore, transmission errors can be used as a specific measurement method instead of electric field strength.

  For example, as a method for determining an appropriate content distribution server, parameters of a transmission path state and a terminal state may be used. In addition, in a content distribution processing system that does not use a server, content is comfortably distributed among members who have the same hobby preference by adding preference parameters in addition to parameters of the transmission path and terminal status. May be.

  Moreover, the form which applied this invention to the delivery form of P2P may be sufficient.

  In the first embodiment, when the terminal device 101 uses the ad hoc mode, the index information 200 is transmitted or received, and when the infrastructure mode can be used, the content is transmitted or received. Also good. This is because the ad hoc mode has a lower communication speed than the infrastructure mode, and is therefore suitable for distributing information having a relatively small amount of data such as the index information 200. This can prevent the processing load of the ad hoc network 103 from becoming too large.

(Embodiment 2)
Next, an ad hoc network system according to the second exemplary embodiment of the present invention will be described. In the second embodiment, the service device manages the index information, and the communication load is reduced by efficiently distributing only the updated part of the frequently updated index information to the terminal device. is there.

  The ad hoc network system according to the second embodiment will be specifically described below. First, the configuration of the ad hoc network system according to the second exemplary embodiment will be described with reference to FIG. In addition, the same code | symbol is provided to the part same as the already demonstrated part, and detailed description is abbreviate | omitted.

  A location information management unit 702 that receives and records current location information (latitude / longitude) periodically sent from the terminal devices 705 and 706 to the service device 701 of the ad hoc network system 700 according to the second exemplary embodiment. Is provided.

  In addition, the service device 701 is provided with an index information management unit 703 that prepares index information for each type of content to be provided and manages the entire index information including the update status of the prepared index information. Also, the index information management unit 703 checks new index information that is periodically updated in the server 105 of the service device 701 and transmits an edit command that is updated difference information to the terminal devices 705 and 706.

  Also, the terminal devices 705, 706a, and 706b according to the second embodiment receive the editing command sent from the service device 701, and update the index information 200 that has already been stored using the received editing command. . The terminal information 705 will be described as an example. The index information management unit 704 updates the index information 200 using an editing command.

  Next, editing commands that are differences in index information will be described with reference to FIG. FIG. 8 is a configuration diagram of an edit command according to the second embodiment. In addition, the same code | symbol is provided to the part same as the already demonstrated part, and detailed description is abbreviate | omitted.

  The edit command 800 is based on the original index information 200 shown in FIG. In addition to the information of the index information 200, the editing command 800 is provided with an editing method 210 such as addition, correction, and deletion for the content name 204.

  As shown in the figure, if the edit command 800 is described as content F, title name, summary, latitude / longitude F, URL, size, and addition, it indicates that the field of content F is newly added to the index information. ing. Further, if the editing method 210 is a correction command, it indicates that a part of the item is updated with new contents. If the editing method 210 is deletion, it indicates that the matching item is deleted.

  As described above, the editing command 800 is provided with editing information for each content.

  Next, index information update processing of the ad hoc network system 700 according to the second embodiment will be described with reference to FIG. FIG. 9 is a sequence diagram of index information update processing of the ad hoc network system 700 according to the second embodiment.

  First, the communication control unit 111 of the terminal devices 705 and 706 periodically notifies the current position information (latitude / longitude) to the service device 701 (ST901).

  On the other hand, the service device 701 records the location information sent from the terminal devices 705 and 706 in the location information management unit 702 (ST902).

  Next, index information management section 703 of service apparatus 701 periodically identifies an area where a large number of terminal apparatuses 705 and 706 exist based on the position information managed by position information management section 702 (ST903).

  Next, based on the identified area, index information management section 703 transmits edit command 800, which is an updated portion of index information, to terminal devices 705 and 706 (ST904). Also, the index information management unit 703 shortens the transmission interval at which the editing command 800 is transmitted in areas where the terminal devices 705 and 706 are denser.

  In this way, by sending an edit command that is update information to an area where the terminal devices 705 and 706 are densely packed, adjacent terminal devices can easily and quickly send and receive edit commands. In 706, the latest editing command can be distributed in a short time. In addition, the editing command 800 can be transmitted to many terminal devices 705 and 706 efficiently by transmitting the editing command 800 to an area where the density of the terminal devices 705 and 706 is high, and the editing command 800 can be distributed. You can expedite.

  In addition, the index information management unit 703 suppresses the frequency of transmitting the editing command 800 by stopping the transmission of the editing command to an area where the terminal devices 705 and 706 do not exist or an area where the terminal devices 705 and 706 are few. Can save bandwidth. As a result, the index information can be updated efficiently.

  Next, the terminal devices 705 and 706 receive the editing command 800 at the communication control unit 111. Then, the index information management unit 703 extracts the editing method 210 described in the received editing command 800 and uses the extracted editing method 210 for the original index information 200 stored in the storage management unit 112. The original index information 200 is updated by performing any one of addition, correction, and deletion processing (ST905).

  As described above, according to the second embodiment, by transmitting only the editing command that is the updated difference information to the terminal device, even if a part of the index information is changed, only the information on the changed part is transmitted. Often, there is no need to transmit an index information portion that is not necessary for updating to the terminal device. Further, since the changing method can be performed by various methods, the index information can be updated easily and efficiently.

  In addition, taking into account temporal factors, temporal changes in the location information of the terminal device may be measured, and editing commands may be distributed according to user behavior patterns such as daytime or nighttime.

  The information terminal device according to the present invention is capable of efficiently broadcasting and receiving content by itself, and is useful for realizing a broadcasting terminal and the like. It can also be applied to applications such as communication terminals.

Configuration diagram of an ad hoc network system according to a first exemplary embodiment of the present invention. The figure explaining the index information concerning Embodiment 1. The figure explaining the operation | movement in which the terminal device concerning Embodiment 1 acquires content beforehand. The flowchart regarding the communication mode switching process of the terminal device concerning Embodiment 1. FIG. Flowchart of relay terminal selection processing of the terminal device according to the first embodiment. Flowchart of the transmission interval determination process of the terminal device according to the first embodiment. Configuration diagram of an ad hoc network system according to a second exemplary embodiment of the present invention. Configuration diagram of edit command according to the second embodiment Sequence diagram of index information update processing of ad hoc network according to the second embodiment

Explanation of symbols

100, 700 Ad hoc network system 101, 102a, 102b, 705, 706a, 706b Terminal device 103 Ad hoc network 104, 701 Service device 105 Server 106 Public network 107 Terminal density measurement unit 108 Moving speed measurement unit 109 Communication mode determination unit 110 Transmission interval Calculation unit 111 Communication control unit 112 Storage management unit 113, 703 Index information management unit 702 Location information management unit

Claims (8)

  A moving speed measuring means for measuring a moving speed, and a communication mode determining means for determining whether to use one of a communication mode of an ad hoc mode using an ad hoc network or an infrastructure mode using a public network based on the measured moving speed; A communication control means for communicating information using the determined communication mode.   The information terminal device according to claim 1, further comprising a moving direction detecting unit that detects a moving direction, wherein the communication mode determining unit switches a communication mode based on a change in the moving direction.   Processing load of information terminal device of communication partner, remaining power of information terminal device, link delay with information terminal device, connection time with information terminal device, importance of information, electric field strength in information terminal device The information terminal device according to claim 1, wherein the communication mode is switched based on at least one of the above.   The information terminal device according to claim 1, wherein the information is index information indicating a content content.   2. The transmission interval calculation unit that calculates the transmission interval of the information based on at least one of the transmission time or version of the information, and the communication control unit transmits information at the transmission interval. The information terminal device according to claim 4.   The communication control means comprises a transmission interval calculation means for calculating a transmission interval of the information based on at least one information among the moving speed, processing load, remaining power, and importance of the information to be transmitted. The information terminal apparatus according to claim 1, wherein information is transmitted at the transmission interval. A service device that manages and distributes information, a relay terminal that relays the information, the information terminal device according to claim 1, an ad hoc network, and a public network,
The information terminal device receives the information distributed from the service device via the public network, and receives the information relayed from the relay terminal via the ad hoc network. system.   8. The ad hoc network system according to claim 7, wherein when the information is changed, the service device distributes only the changed difference.

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