Terminals that enable information sharing through inter-terminal communication

Abstract

To provide terminal-to-terminal communication capable of reducing redundant relay more efficiently than before without requiring overhead and information collection processes, and thereby to achieve a more efficient information sharing method.SOLUTION: A terminal apparatus used for terminal-to-terminal communication includes a wireless communication unit that communicates with another terminal apparatus, a data management unit that manages information packets to be communicated, and a storage unit that stores the information packets. The data management unit refers to the storage unit to select a transmittable information packet, creates an index packet corresponding to the selected information packet, and sends the created index packet to the wireless communication unit. The wireless communication unit transmits the index packet sent.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to communication between terminals without using central control. In particular, it relates to a method for sharing information in communication between terminals (such as smartphones, tablets, game machines, sensors, etc.) for the purpose of sharing information between terminals. Furthermore, it relates to a terminal device that realizes the information sharing method.

Background Art

[0002] Communication between terminals without using central control (device-to-device communication) has excellent characteristics in terms of cost and convenience because it does not require other communication infrastructures. The international standard IEEE802.15.8 that defines PHY (physical layer (so-called layer 1)) and MAC (logical layer (so-called) layer 2) specifications without using central control has been issued. As a suitable example of communication between terminals, direct communication between mobile terminals (such as smartphones, tablets, game machines, etc.), between moving objects (cars, drones, ships), and between sensor-equipped terminals can be considered. As applications, sharing of position information between moving objects, sharing of information within a region, sharing of sensor information, emergency transmission, etc. are assumed.

[0003] The use of communication between terminals is expected even in cases where it is not suitable for constructing a central control type network or in regions where the communication infrastructure is not developed. The present invention targets communication between terminals without using central control. A moving terminal and a non-moving terminal may coexist at the same time. The terminal accesses the wireless channel using CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). Also, the information transmitted and received between terminals is divided into general information and information with a high degree of urgency (important information). In particular, it relates to a method for sharing information in communication between terminals that can improve the utilization efficiency of the wireless frequency resources to be used.

[0004] Conventional technology When sharing information using terminal-to-terminal communication, terminals within the communication range of the transmitting terminal receive the information directly, but terminals outside the transmitting terminal's communication range need to receive the information via a relay from another terminal. If mobile terminals are included, the relay range is expanded by the movement of these mobile terminals. On the other hand, because there is no central control terminal, each terminal may relay the same information packets redundantly (hereinafter referred to as redundant relaying). By relaying information packets, the arrival of the information packets is ensured. However, redundant relaying of information packets leads to problems such as a decrease in the efficiency of wireless resource utilization and an increase in the probability of collisions between transmitted packets.

[0005] Prior art addressing such problems can be found in Patent Documents 1 and 2, which will be discussed later. Patent Document 1 attempts to solve the above problem using scheduling. Patent Document 2 shows an example of improvement achieved by limiting the number of relays through inter-terminal cooperation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-115666 [Patent Document 2] Japanese Patent Publication No. 2019-122032 [Overview of the project] [Problems that the invention aims to solve]

[0007] While the scheduling method described in Patent Document 1 is effective in reducing unnecessary duplicate relaying of information packets, it has the problem of incurring heavy communication overhead for scheduling in inter-terminal communication that does not use central control. Patent Document 2 reduces overhead by using cooperation between terminals, but this has the problem that it requires processes such as information gathering and coordination to achieve that cooperation.

[0008] The present invention relates to a technology for reducing redundant relaying and improving the utilization efficiency of radio frequency resources in terminal-to-terminal communication that does not use central control. The present invention aims to realize an information sharing method for inter-terminal communication that can reduce redundant relaying more efficiently than conventional methods, without requiring overhead for scheduling or inter-terminal coordination, or information gathering processes. [Means for solving the problem]

[0009] This invention is characterized by its ability to differentiate the priority of important information and general information in information sharing via terminal-to-terminal communication without central control, while maintaining a predetermined information packet delivery rate and reducing unnecessary packet duplication. The specific method is as follows.

[0010] (1) In order to solve the above problems, the present invention provides a terminal device used for terminal-to-terminal communication, comprising: a wireless communication unit that communicates with other terminal devices; a data management unit that manages information packets to be communicated; and a storage unit that stores the information packets, wherein the data management unit selects information packets that can be transmitted by referring to the storage unit, creates an index packet corresponding to the selected information packet, sends the created index packet to the wireless communication unit, and the wireless communication unit transmits the received index packet.

[0011] (2) The present invention also relates to the terminal described in (1), wherein the wireless communication unit receives an information request packet transmitted from the other terminal, sends the information request packet to the data management unit, the data management unit retrieves an information packet corresponding to the transmitted information request packet from the storage unit, sends the retrieved information packet to the wireless communication unit, and the wireless communication unit transmits the transmitted information packet.

[0012] (3) The present invention relates to a terminal device used for terminal-to-terminal communication, comprising: a wireless communication unit that communicates with other terminal devices; and a frame management unit that manages frames for terminal-to-terminal communication, wherein the wireless communication unit receives an information request packet transmitted from the other terminal device, sends the information request packet to the frame management unit, the frame management unit calculates the time required to transmit an information packet corresponding to the transmitted information request packet, instructs the wireless communication unit not to access the channel during the calculated time, and the wireless communication unit refrains from accessing the channel based on the instruction.

[0013] (4) The present invention also relates to a terminal as described in (1), further comprising a frame management unit for managing frames of inter-terminal communication, wherein the frame includes a priority access section, and the frame management unit instructs the wireless communication unit to transmit the index packet in all frame sections including the priority access section.

[0014] (5) The present invention also relates to a general terminal as described in (1), further comprising a frame management unit for managing frames of inter-terminal communication, wherein the frames include a priority access section, and the frame management unit instructs the wireless communication unit to transmit the index packet only in sections other than the priority access section.

[0015] (6) In order to solve the above problems, the present invention provides a terminal device used for terminal-to-terminal communication, comprising: a wireless communication unit that communicates with other terminal devices; a data management unit that manages information packets that are the target of communication; and a storage unit that stores the information packets, wherein the wireless communication unit receives an index packet transmitted by another terminal device, sends the received index packet to the data management unit, the data management unit selects an element from the transmitted index packet that corresponds to an information packet not possessed by its own terminal, creates an information request packet corresponding to the selected element, sends the information request packet to the wireless communication unit, and the wireless communication unit transmits the received information request packet to the other terminal device that transmitted the index packet.

[0016] (7) The present invention also relates to the terminal described in (6), wherein the wireless communication unit broadcasts the received information request packet to the other terminal that sent the index packet.

[0017] (8) The present invention also relates to the terminal described in (6), wherein the wireless communication unit receives the information packet that has been sent, and sends the received information packet to the data management unit, The data management unit is a terminal device characterized by analyzing the received information packets and storing their contents in the storage unit.

[0018] (9) The present invention also relates to a terminal as described in (6), further comprising a frame management unit for managing frames of inter-terminal communication, wherein the frames include priority access sections, and the frame management unit instructs the wireless communication unit to transmit the information request packets in all frame sections including the priority access sections.

[0019] (10) Further, the present invention is the terminal device according to (6), further comprising a frame management unit that manages frames for inter-terminal communication, wherein the frame includes a priority access section, and the frame management unit is characterized in that it instructs the wireless communication unit to transmit the information request packet only in a section other than the priority access section.

Advantages of the Invention

[0020] According to the present invention, in a method of sharing information by inter-terminal communication without using central control, it is possible to improve the utilization efficiency of radio frequency resources.

Brief Description of the Drawings

[0021] [Figure 1] It is a configuration diagram of a terminal device used for inter-terminal communication according to this embodiment. [Figure 2] It is a configuration diagram of a terminal device provided with a sensor device and a camera. [Figure 3] It is an explanatory diagram of a frame configuration used in the communication in this embodiment. [Figure 4] It is an example of a sequence diagram of an information packet distribution sequence in this embodiment. [Figure 5] It is an example of a sequence diagram of an information packet distribution sequence in this embodiment, which is a continuation of FIG. 4. [Figure 6] It is a configuration diagram showing a configuration example of Specific Example 1 in this embodiment. [Figure 7] It is a configuration diagram showing a configuration example of Specific Example 2 in this embodiment.

Modes for Carrying Out the Invention

[0022] Hereinafter, a terminal device according to a preferred embodiment of the present invention and an inter-terminal communication system using the terminal device will be described based on the drawings. Further, the operation of an information sharing method for inter-terminal communication on the terminal device and the inter-terminal communication system will be described based on the drawings. In this embodiment, the term "terminal" is used, but this refers to a device generally called a "wireless terminal" or simply a "terminal." The terminal may consist of various computers equipped with a wireless communication unit that performs wireless communication. The terminal may also be constructed as a dedicated device. However, for example, a smartphone, tablet, laptop, etc., may be operated as a terminal by installing a predetermined application program on it.

[0023] A.Configuration (A-1) Basic configuration of the terminal First, terminals that hold important information are called priority terminals, and terminals that hold general information are called general terminals. Priority terminals and general terminals may be fixedly designated, for example, terminals with public use (priority terminals) and general user terminals (general terminals). Furthermore, instead of fixing the distinction between priority terminals and general terminals, the status of a terminal may be changed ad hoc based on the attributes of information transmitted from the application layer, etc. Figure 1 shows the configuration of a terminal 10 according to a preferred embodiment of the present invention. The terminal 10 includes a wireless communication unit 14 that communicates with other terminals 10 via an antenna 12, a data management unit 16 that stores, manages, and processes data, a storage unit 17 that stores data such as information packets, and a frame management unit 18 that manages the synchronization of wireless communication frames and the transmission timing of various packets. Here, various packets include index packets, information request packets, information packets, etc.

[0024] The wireless communication unit 14 communicates with other terminals (general terminals, priority terminals) 10. The wireless communication unit 14 is a communication device equipped with the function of sending and receiving wireless signals based on a predetermined communication standard. It sends and receives predetermined packets according to instructions from the data management unit 16 and the frame management unit 18. The predetermined communication standard executed by this wireless communication unit may be one of various communication standards. For example, it may be a wireless LAN such as Wi-Fi (IEEE802.11) or a long-range wireless communication standard such as LPWA (Low Power Wide Area) such as LoRa.

[0025] The data management unit 16 is a computer comprising a CPU / MPU equipped with general-purpose memory, etc., and performs the management of data to be communicated. This data management unit 16 performs predetermined operations by the CPU / MPU executing predetermined application programs stored in memory, etc. In other words, the operation of this data management unit 16 is described by predetermined application programs.

[0026] The storage unit 17 stores information packets and the like managed by the data management unit 16. Information packets and the like held by the terminal device 10 are stored in this storage unit 17. In this embodiment, an example in which the terminal device 10 includes the storage unit 17 is described, but the storage unit 17 may be located anywhere. For example, the storage unit 17 may be provided outside the terminal device 10 in a form connected as an external storage device. Furthermore, the memory unit 17 may be used as a storage location for various application programs controlled by the terminal device 10.

[0027] The frame management unit 18, like the data management unit 16, is a computer comprising a CPU / MPU equipped with general-purpose memory, etc., and manages the timing of frame operation and the transmission timing of various packets based on the synchronization process specified in the standard IEEE 802.15.8 and GPS 1PPS, etc. This frame management unit 18 operates when the CPU / MPU executes a predetermined application program stored in predetermined memory, etc. (which may also be the storage unit 17 mentioned above). In other words, the operation of this frame management unit 18 is described by a predetermined application program.

[0028] The data management unit 16 and the frame management unit 18 may both be configured on the same computer. The CPU / MPU of this computer executes an application program that implements the functions of the data management unit 16 to realize the functions of the data management unit 16. Alternatively, the CPU / MPU of this computer may be configured to execute an application program that implements the functions of the frame management unit 18 to realize the functions of the frame management unit 18.

[0029] Priority terminals and regular terminals As explained above, terminal 10 can be divided into two types: priority terminals and general terminals. The configurations of priority terminals and general terminals are basically the same as shown in Figure 1. However, the operation of the frame management unit 18 (frame management function) is different, and they differ in that they determine the priority of important information and process it accordingly. In a preferred embodiment, there is one application program that implements the frame management unit 18, and it may be configured to determine whether the terminal operates as a priority terminal or a general terminal via a GUI. The terminal 10 may be fixed as either a priority terminal or a general terminal by fixing a switch. Alternatively, the user may switch the switch according to the application to set the terminal 10 as either a priority terminal or a general terminal.

[0030] In another preferred embodiment, the application program implementing the frame management unit 18 may be a single type, and the terminal may be configured to operate as a priority terminal or a general terminal depending on the attributes of the transmitted information. As a result, one terminal can be made to operate as a priority terminal in some cases and as a general terminal in other cases. Terminal 10 may also be used by fixing it as either a priority terminal or a general terminal.

[0031] (A-2) Connection with sensors, etc. Figure 2 shows an example configuration when sensors and other devices are connected to the terminal device 10. In this example, various sensor devices 20 and a camera 22 are connected to the data management unit 16. With this configuration, the data management unit 16 can create information packets containing sensor data from the sensor devices 20 and image data captured by the camera 22, and transmit the created information packets to other terminal devices 10 via the wireless communication unit 14. The created information packets may be stored in the storage unit 17.

[0032] B. Operation (i-1) Index packet, information request packet Figure 3 shows an explanatory diagram of the frame configuration used in communication in this embodiment. In this embodiment, in order to reduce unnecessary packet relaying, an index packet 44 corresponding to a series of information packets 46 is first constructed (see Figure 3). The index packet 44 is composed of multiple elements, and each element contains data for identifying the information packet 46 (transmitter ID, information packet ID, transmission time, etc.). This data for identification is called identification data. Furthermore, there is a one-to-one correspondence between the elements in the index packet 44 and the information packets. Furthermore, the size of the index packet 44 and the number of information packets 46 that can be delivered at one time are limited. As a result, there is a maximum number of elements that make up the index packet 44.

[0033] (i-2) Information Request Packet Furthermore, an information request packet 50 is constructed (see Figure 3). The information request packet 50 is composed of elements selected from the index packet 44. The sizes of the index packet 44, the information request packet 50, and the information packet 46 may be predetermined. Alternatively, they may be of variable length, varying depending on the amount of data and the amount of identification data. Generally, the sizes of the index packet 44 and the information request packet 50 can be set to be smaller than the size of the information packet 46. Each terminal 10 stores its own information packets 46 in its storage unit. The storage unit of the terminal 10 may also store the application program described above.

[0034] (c) CSMA / CA Generally, terminal 10 transmits an index packet 44, an information request packet 50, or an information packet 46 via CSMA / CA. When terminal 10 (the transmitting side) attempts to send an index packet 44, for example, it first obtains channel access rights via CSMA / CA before sending the index packet 44. Specifically, the data management unit 16 creates an index packet 44 based on the contents of the storage unit 17. The wireless communication unit 14 also acquires channel access rights via CSMA / CA. Furthermore, the terminal 10 (receiving side), upon receiving the index packet 44, first obtains channel access rights via CSMA / CA before sending the information request packet 50, for example, before sending the information request packet 50. The data management unit 16 also creates the information request packet 50, similar to the index packet 44. Furthermore, the wireless communication unit 14 acquires channel access rights via CSMA / CA before transmitting the information request packet 50.

[0035] (e) Frame configuration to be adopted (Figure 3) All terminal devices 10 communicate using the frame configuration shown in Figure 3. 40 sync slots As shown in Figure 3, a synchronization slot 40 is provided at the beginning of the frame configuration. In the synchronization slot 40, the synchronization process specified in the standard IEEE 802.15.8 may be performed. Alternatively, synchronization based on GPS (Global Positioning System) 1PPS (Pulse Per Second) or other synchronization operations may be performed.

[0036] Priority access period 42 A priority access section 42 is provided in the section following the synchronization slot 40 (see Figure 3). Only the priority terminal 10a, as explained in (A-1) "Priority terminals and general terminals" above, is configured to be able to use this priority access section 42.

[0037] Index Packet 44 (Index Slot) Figure 3 shows how an index packet 44 is transmitted within the priority access section 42. The time required to transmit this index packet 44 is called an index slot. Here, the length (time) of the priority access section 42 can be freely configured to range from the length of one index slot to the length equivalent to multiple index slots. Furthermore, the length of this priority access section 42 may include the length of the contention period required for the terminal 10 to access the channel based on CSMA / CA. The use of frames from the priority access section 42 onward can be utilized not only by the priority terminal 10a but also by any terminal 10.

[0038] (e) Specific examples of processing operations As shown in Figure 3, each frame starts from synchronization slot 40. In Figure 3, time progresses from left to right. That is, a frame starts on the left and completes on the right. In actual communication, this frame communication is repeatedly executed. Following the synchronization slot 40, the priority access section 42 begins. As described above, only the priority terminal 10a can use this priority section 42. The priority terminal 10a selects up to the single transmission limit of information packets 46 from the information packets 46 it possesses, and broadcasts the corresponding index packets 44 in the priority access section 42. Specifically, the data management unit 16 refers to the storage unit 17, selects up to the maximum number of information packets 46 that can be transmitted at once, and creates corresponding index packets 44. The data management unit 16 sends the created index packets 44 to the wireless communication unit 14 and instructs it to broadcast them. Based on this instruction, the wireless communication unit 14 broadcasts the index packets 44. Note that the single-transmission limit here refers to the maximum number of information packets 46 that can be sent at one time.

[0039] If there are multiple priority terminals 10a If there are multiple priority terminals 10a, priority terminals 10a may access the priority access section 42 via CSMA / CA. The frame management unit 18 of the priority terminal 10a instructs the wireless communication unit 14 to acquire access rights in any section within the frame. The wireless communication unit 14 acquires access rights via CSMA / CA based on the instruction and then broadcasts an index packet 44. This acquisition of access rights and broadcasting operation may be performed in the priority access section 42 or in other sections within the frame. Furthermore, if there are multiple priority terminals 10a, the priority access section 42 may be fixedly assigned to the priority terminals 10a. For example, if there are two priority terminals 10a, the first half of the priority access section 42 may be fixedly assigned to one priority terminal 10a, and the second half of the priority access section 42 may be fixedly assigned to the other priority terminal 10a. For example, if the number of priority terminals 10a is fixed, such a fixed assignment may be applied instead of CSMA / CA. The following describes the process after priority terminal 10a broadcasts index packet 44.

[0040] (a) The broadcasted index packet 44 is received by another terminal 10 (priority terminal 10a or general terminal 10b). The wireless communication unit 14 of the other terminal 10 performs the reception and sends the index packet 44 to the data management unit 18. Of the (one or more) terminals 10 that receive the index packet 44, only one terminal 10 acquires access rights to the channel via CSMA / CA. When the wireless communication unit 14 receives the index packet 44, it sends the index packet 44 to the data management unit 16 and sends a reception completion signal to the frame management unit 18. Alternatively, instead of sending a reception completion signal, the index packet 44 itself may be sent to the frame management unit 18.

[0041] The frame management unit 18 then instructs the wireless communication unit 14 to acquire channel access rights. Based on these instructions, the wireless communication unit 14 acquires channel access rights via CSMA / CA. However, in the priority access section 42, this acquisition of access rights is only possible for the priority terminal 10a that received the index packet 44. That is, in the priority access section 42, the frame management unit 18 of the priority terminal 10a can instruct the wireless communication unit 14 to acquire channel access rights. Outside of the priority access section 42, any terminal 10 that receives the index packet 44 can acquire access rights. In other words, in sections other than the priority access section 42, either the frame management unit 18 of the priority terminal 10a or the general terminal 10b can instruct the wireless communication unit 14 to acquire channel access rights. In other words, the frame management unit 18 of the priority terminal 10a can instruct the wireless communication unit 14 to acquire channel access rights in all frame segments, including the priority access segment 42. In contrast, the frame management unit 18 of the general terminal 10b can instruct the wireless communication unit 14 to acquire channel access rights only in segments other than the priority access segment 42.

[0042] Thus, in this embodiment, in the priority access section 42, only the priority terminal 10a can acquire access rights, and as a result, it can transmit various packets preferentially. In sections other than the priority access section 42, both the priority terminal 10a and the general terminal 10b can acquire access rights, and both can transmit various packets.

[0043] The terminal 10 that has acquired access rights in this way is referred to here as the authorized terminal 10c. The authorized terminal 10c extracts the element corresponding to the information packet 46 that it does not possess from the received index packet 44 and generates an information request packet 50 corresponding to this element. Specifically, the data management unit 16 of the authorized terminal 10c selects information packets 46 (corresponding to elements) that the terminal does not possess from among the elements of the received index packet 44, and creates an information request packet 50 corresponding only to the selected elements. Here, there is one or more information packets 46 (corresponding to elements) to be selected. If there are no information packets 46 to select, no information request packet 50 is created. Since the information packets 46 that the terminal possesses are stored in the storage unit 17, the data management unit 16 can select information packets 46 (corresponding to elements) that the terminal does not possess by referring to the storage unit 17. The specific information packet 46 to be selected may vary depending on the application. The information packet 46 to be selected can be arbitrarily determined depending on the purpose. The data management unit 16 sends the created information request packet 50 to the wireless communication unit 14. As described above, after acquiring channel access rights, the wireless communication unit 14 broadcasts the information request packet 50 sent from the data management unit 16 to the terminal 10 that broadcast the index packet 44. In the example described here, the priority terminal 10a broadcast the index packet 44, so the wireless communication unit 14 broadcasts the information request packet 50 to that priority terminal 10a.

[0044] Timing of sending information request packets Here, if the authorized terminal 10c is a different priority terminal 10a from the transmitting priority terminal 10a, the information request packet 50 can be broadcast even within the priority access section 42. However, if the authorized terminal 10c is a general terminal 10b, channel access becomes possible after the priority access section ends, so the information request packet 50 can be broadcast after the priority access section ends.

[0045] (b) The priority terminal 10a that broadcast the index packet 44 receives the information request packet 50 that was broadcast as described in (a). The wireless communication unit 14 of the priority terminal 10a receives this information request packet 50 and sends it to the data management unit 16. The data management unit 16 retrieves the information packet 46 corresponding to the element described in the information request packet 50 from the storage unit 17 and sends the retrieved information packet 46 to the wireless communication unit 14. The wireless communication unit 14 broadcasts the information packet 46. The broadcasted information packet 46 is received by the authorized terminal 10c and all receivable terminals 10. The operation of the receiving terminals 10 will be described later in (c).

[0046] Meanwhile, other terminals 10 besides the priority terminal 10a that broadcast the index packet 44 also receive the broadcasted information request packet 50. Specifically, the wireless communication unit 14 of the other terminals 10 receives the information request packet 50 and sends it to the frame management unit 18. The frame management unit 18 calculates the time (= number of information packets) required for (the priority terminal 10a) to transmit the information packets 46 corresponding to the elements of the broadcasted information request packet 50, and refrains from accessing the channel during that calculated time. Specifically, the frame management unit 18 instructs the wireless communication unit 14 not to access the channel until that time has elapsed. Based on this instruction, the wireless communication unit 14 does not access the channel.

[0047] One of the distinctive features of this embodiment is that the frame management unit 18 inspects the contents of the information request packet 50 transmitted by the other terminal 10 and suspends access to the channel from the wireless communication unit 14 for a predetermined period of time. In this way, by using "broadcast" to send the information request packet 50, a suppressive effect against interference from "hidden terminals" (described in detail in the next paragraph) can be obtained. Here, suppression means refraining from accessing the channel or prohibiting transmission.

[0048] Hidden terminal When the priority terminal 10a is transmitting, other terminals 10 cannot transmit due to CSMA / CA. For example, if the priority terminal 10a and other general terminals 10e are outside each other's communication range, they can transmit simultaneously regardless of CSMA / CA. On the other hand, when authorized terminal 10c is within communication range of both priority terminal 10a and general terminal 10e, a so-called collision occurs when both priority terminal 10a and general terminal 10e transmit to authorized terminal 10c simultaneously. In this case, priority terminal 10a and general terminal 10e are said to be "hidden terminals" of each other. When authorized terminal 10c sends an information request packet 50 to priority terminal 10a, general terminal 10e can eavesdrop on it and refrain from sending its own packet. As a result, collisions can be avoided.

[0049] (c) All terminals 10 that received the broadcasted information packet 46 as described above, including the authorized terminal 10c that broadcast the information request packet 50, update the information packets 46 that each terminal possesses using the received information packet 46. That is, they store the contents of the received information packet 46 in the storage unit 17. Specifically, in the terminal device 10 that receives the information packet, the wireless communication unit 14 receives the information packet 46 and sends it to the data management unit 16. The data management unit 16 analyzes the received information packet 46 and stores its contents in the storage unit 17. Depending on the contents of the information packet, the information packet may be stored in the storage unit 17 as is, or the contents of the information packet may be reflected in the storage unit 17 to update the data (such as updating to the latest data). Also, if an information packet 46 similar to an information packet 46 already in the storage unit 17 is received, the received information packet 46 may be discarded. The specific operations may vary depending on the contents and type of the information packet 46. These various operations are collectively referred to as "update" or "update information" in this embodiment.

[0050] (k) Processing sequence Here, the terminal 10 that sends the information packet is referred to as the transmitting terminal 10d. (C-1) The transmitting terminal 10d broadcasts the index packet 44. (C-2) The terminal device 10 that receives the information packet receives the index packet 44 and broadcasts the information request packet 50. (C-3) The transmitting terminal 10d broadcasts the information packet requested in the information request packet 50. (C-4) A step in which the terminal 10 that has received the broadcasted information packet updates the contents of the memory unit 17 of its own terminal. This series of steps is called a "processing sequence." In other words, a processing sequence consists of the four types of steps described above.

[0051] (k) Processing after the end of the priority access section 42 After the priority access section 42 ends, general terminals 40b will be able to access the channel. This access will be based on CSMA / CA. Furthermore, if a general terminal 10b has received an index packet 44 from a priority terminal 10a during the priority access section 42, and the general terminal 10b desires the information packets related to the index packet 44, the general terminal 10b will begin processing by broadcasting an information request packet 50. Figure 3 illustrates this situation, showing that an information request packet 50 is sent immediately after the priority access section 42 ends. This information request packet 50 is sent by a general terminal 10b that acquired channel access rights after the priority access section 42 ended.

[0052] Processing sequence after the end of priority access section 42 When the above-described "processing sequence," which begins with the step in which the priority terminal 10a broadcasts the index packet 44 (as described in step K-1 above), is completed, or when the priority terminal 10a does not send the index packet 44 (in the priority access section 42), the general terminal 10b, which has acquired channel access rights, can perform the following processing. In short, the general terminal 10b becomes the transmitting terminal 10d and starts the processing sequence as described above.

[0053] (a) First, a general terminal 10b that has acquired channel access rights can select up to the number of information packets it has stored in its storage unit 17 that can be transmitted at one time, and broadcast an index packet 44 corresponding to the selected information packets. Specifically, the data management unit 16 inspects the storage unit 17 to check for the presence of information packets up to the single transmission limit. If information packets up to the single transmission limit exist, it instructs the frame management unit 18 to acquire channel access rights. The frame management unit 18 acquires channel access rights based on CSMA / CA. After acquiring channel access rights, the data management unit 16 selects information packets up to the single transmission limit from the storage unit 17, creates an index packet 44 corresponding to the selected information packets, sends the index packet 44 to the wireless communication unit 14, and instructs the wireless communication unit 14 to broadcast it. As a result, the wireless communication unit 14 broadcasts the index packet 44.

[0054] (b) Another terminal 10 that receives the broadcasted index packet 44 acquires access rights to the channel via CSMA / CA. The other terminal 10 then extracts elements from the index packet 44 that correspond to information packets not held by its own terminal and generates an information request packet 50 corresponding to those elements. The other terminal 10 then broadcasts the generated information request packet 50 to the terminal that broadcast the index packet 44 (transmitting terminal 10d). Specifically, when the wireless communication unit 14 of another terminal 10 receives the index packet 44, it sends the index packet 44 to the data management unit 16 and the frame management unit 18.

[0055] First, when the frame management unit 18 detects the reception of the index packet 44, it instructs the wireless communication unit 14 to acquire access rights to the channel via CSMA / CA. The wireless communication unit 14 acquires access rights via CSMA / CA and notifies the data management unit 16 and the frame management unit 18 of this. Meanwhile, the data management unit 16 examines the elements of the index packet 44 and the storage unit 17, and extracts elements corresponding to information packets that the terminal does not possess. Based on these extracted elements, the data management unit 16 generates an information request packet 50. After receiving notification from the wireless communication unit 14 that it has acquired access rights, the data management unit 16 sends the generated information request packet 50 to the wireless communication unit 14, instructing it to broadcast it to the transmitting terminal 10d. The wireless communication unit 14 then broadcasts the information request packet 50 to the transmitting terminal 10d in accordance with this instruction.

[0056] (c) Next, the terminal (transmitting terminal 10d) that is the destination of the broadcasted information request packet broadcasts an information packet corresponding to the element described in the broadcasted information request packet 50. In addition, another terminal 10 that has intercepted the broadcasted information request packet calculates the time (number of information packets) required to transmit the information packets corresponding to the element contained in the broadcasted information request packet 50, and refrains from accessing the channel for the amount of time calculated.

[0057] Specifically, the wireless communication unit 14 of the transmitting terminal 10d receives the broadcasted information request packet 50 and sends the information request packet 50 to the data management unit 16. The data management unit 16 examines the information request packet 50 and sends the information packet 46 corresponding to the element within it to the wireless communication unit 14, instructing it to broadcast it. Upon receiving this instruction, the wireless communication unit 14 broadcasts the information packet 46. Here, the data management unit 16 may retrieve the information packet 46 corresponding to the above element from, for example, the storage unit 17 and send it to the wireless communication unit 14. The information packet 46 may be stored in the storage unit 17 in this way, but it may also be configured to be located in another location, for example, on the cloud. The wireless communication unit 14 broadcasts the received information packet 46 upon instruction from the data management unit 16.

[0058] In this embodiment, the wireless communication unit 14 of the other terminal 10 receives (intercepts) the broadcasted information request packet 50 and sends the received information request packet 50 to the frame management unit 18. The frame management unit 18 calculates the time (number of information packets) required to transmit information packets corresponding to the elements of the broadcasted information request packet, and instructs the wireless communication unit 14 to refrain from accessing the channel for the calculated time. As a result, the wireless communication unit 14 refrains from accessing the channel for the instructed time. This type of operation allows for efficient access to channels, enabling more efficient use of those channels.

[0059] (d) Next, all terminals 10 that have received the broadcasted information packet update their own stored information packets using the received information packet. Here, "all terminals 10 that have received the information packet" of course includes the terminal 10 that broadcast the information request packet 50 (the terminal 10 that requested the information packet from the transmitting terminal 10d).

[0060] Specifically, the wireless communication unit 14 of the terminal device 10 on the channel receives the information packet broadcast by the transmitting terminal 10d. The wireless communication unit 14 sends the received information packet to the data management unit 16. The data management unit 16 updates the information packets held by its own terminal using the received information packet. For example, the data management unit 16 may store the received information packet in the storage unit 17 within its own terminal. Alternatively, the data management unit 16 may update the contents of the information packets held by its own terminal based on the received information packet. This operation is performed by terminal 10, which receives the broadcasted information packet.

[0061] (Ke) Example of a distribution sequence Figures 4 and 5 show an example of a sequence diagram of an information packet distribution sequence using the method of this embodiment (the present invention). In Figures 4 and 5, time is depicted as progressing from top to bottom. Figure 4 shows the communication of a predetermined frame and the following frame. Figure 5 shows the communication of another frame that follows. Furthermore, the example shown in Figures 4 and 5 shows the communication between priority terminal P1, general terminal U1, and general terminal U2.

[0062] In Figure 4, one frame starts at time t1, and the synchronization slot 40a is from time t2 to time t2. The priority access section 42a is from time t2 to time t3. In Figure 4, the sequence that follows is first depicted when the priority terminal P1 sends an index packet 44a during the priority access period 42a. Following this sequence, Figure 4 also depicts another sequence that begins after the priority access period 42a has ended, when the general terminal U1 sends an index packet 44c. The following describes each sequence.

[0063] The index packet 44a transmitted by priority terminal P1 and the sequence initiated thereby In the example shown in Figure 4, an index packet 44a is transmitted from the priority terminal P1 during the priority access section 42a. This index packet can be received by the general terminal U1. The priority access section 42a ends at time t3. Therefore, general terminals U1 and U2 become able to send index packets 44b. During the priority access section 42a, priority terminal P1 sends index packet 44a, which general terminal U1 receives. Subsequently, general terminal U2 sends index packet 44b, which general terminal U1 receives, but since priority terminal P1 has already received index packet 44a, the later received index packet 44b is discarded. This is indicated by an "x" mark and "Discard (P1 priority)".

[0064] Next, among the other terminals 10 that received the index packet 44a, general terminal U1 finds the information packet it wants to obtain based on the contents of the index packet 44a. As a result, general terminal U1 sends an information request packet 50a containing the elements of the desired information packet. This information request packet 50a is addressed to priority terminal P1, which sent the index packet 44a. Priority terminal P1, upon receiving the information request packet 50a, sends n information packets 46-1, 46-2, ..., 46-n based on the contents of the information request packet 50a (see Figure 4). Here, n is a natural number. Note that in Figure 4, intermediate information packets 46-3 to n-1 are omitted and not shown.

[0065] Meanwhile, the information request packet 50a is also received by a general terminal U2, which is one of the other terminals 10. The general terminal U2 can find out what kind of information packets are being requested from the received information request packet 50a. Based on the information it has learned, the general terminal U2 can understand that information packets 46-1 to 46-n, as described above, will be transmitted, and can calculate the transmission time from the amount of data. This calculation is performed by the frame management unit 18 as described above, and determines the time during which there is no channel access as shown in Figure 4. The frame management unit 18 issues an instruction to the wireless communication unit 14 not to access the channel during that time (see Figure 4).

[0066] Index packet 44c transmitted by general terminal U1 and the sequence initiated thereby After the general terminal U1 has finished receiving the desired information packets 46-1, 46-2, ..., 46-n, the data management unit 16 of the general terminal U1 stores the received information packets in the storage unit 17. The general terminal U1 determines that new information has been stored in the memory unit 17 and therefore it is necessary to transmit it further. While such determinations vary depending on the application, in this embodiment, we will continue the explanation assuming that the general terminal U1 has determined that it is necessary to transmit new information. General terminal U1 first acquires channel access rights in order to send a new index packet 44c. After acquiring these channel access rights, general terminal U1 sends the index packet 44c as shown in Figure 4. The data management unit 16 of general terminal U1 creates an index packet 44c to distribute the data in the storage unit 17 to other terminals 10 and sends it to the wireless communication unit 14. After acquiring channel access rights, the wireless communication unit 14 sends the index packet 44c.

[0067] Next, priority terminal P1 receives index packet 44c. The wireless communication unit 14 of priority terminal P1 receives index packet 44c and sends it to data management unit 16. Based on the contents of this index packet 44c, the data management unit 16 creates an information request packet 50b as needed and sends it to wireless communication unit 14. Wireless communication unit 14 transmits the information request packet 50b (see Figure 4). Then, general terminal U1 receives it (see Figure 4). Furthermore, the same processing as that performed in the priority terminal P1 is carried out in the general terminal U2, and an information request packet 50c is sent as needed. However, the general terminal U1 discards this request packet 50c even if it receives it. This is because the wireless communication unit 14 of the general terminal U1 has already received an information request packet 50b from the priority terminal P1, and the data management unit 16 has already started processing the information request packet 50b. In other words, even if the wireless communication unit 14 receives another information request packet 50c while the data management unit 16 is processing the information request packet 50b, it is ignored and discarded.

[0068] The data management unit 16 creates information packets 46-#1 and 46-#2 in response to the information request packet 50b and sends them to the wireless communication unit 14. The wireless communication unit 14 transmits these information packets 46-#1 and 46-#2 (see Figure 4). Furthermore, "processing" of the information request packet 50b by the data management unit 16 refers to the period from when the processing begins until information packets 46-#1 and 46-#2 are created and sent to the wireless communication unit 14. Any other information request packets 50 received during this "processing" period are discarded as described above. This discarding is indicated by an "x" in Figure 4.

[0069] Processing the next frame Figure 5 shows an example of the processing for the next frame, following the completion of the processing shown in Figure 4. Figure 5 is a continuation of the time chart shown in Figure 4, that is, an example of the processing in the next frame. In the frame shown in Figure 5, after the synchronization slot 40b and priority access period 42b have ended, the general terminal U2 sends the index packet 44d. In the example shown in Figure 5, there is no transmission from priority terminal P1 during the priority access period, and after the priority access period is completed, the general terminal U2 sends the index packet 44d. This operation is basically the same as the process in Figure 4 where the general terminal U1 sends the index packet 44c.

[0070] Next, the general terminal U1 receives the index packet 44d and sends an information request packet 50d accordingly. This processing operation is the same as described in Figure 4 (information packet 50b). General terminal U2 receives this information request packet 50d and, in response, sends information packets 46-n1 and 46-n2. General terminal U1 receives these information packets 46-n1 and 46-n2 and stores them in its internal storage unit 17. These processes are the same as those described in Figure 4.

[0071] Furthermore, when the priority terminal P1 receives the information request packet 50d, it calculates the transmission time of the information packets 46-n1 and 46-n2 to be transmitted based on its contents. Then, it refrains from accessing the channel for the calculated period. Specifically, based on the information request packet received by the wireless communication unit 14, the frame management unit 18 calculates the transmission time of the information packets 46-n1 and 46-n2, and during that time, the wireless communication unit does not access the channel. This process is the same as the process explained in Figure 4, and in Figure 5, it is represented as "Do not access the channel during other transmission periods."

[0072] C. Specific Examples (C) Specific example 1 Figure 6 shows a concrete example of an actual implemented configuration, where multiple general terminals 100a, 100b, 100c, and 100d are deployed over a wide area. The operation of this configuration will be explained below. General terminals 100a and 100b are positioned at a distance from each other that allows them to communicate. On the other hand, general terminal 100d is positioned at a distance from which it cannot communicate with either general terminal 100a or general terminal 100b. General terminal 100c is moving, and when it is close to general terminals 100a and 100b, it can only communicate with general terminals 100a and 100b. Also, when general terminal 100c is close to general terminal 100d, it can only communicate with general terminal 100d.

[0073] In this specific example 1, only the general terminal 100c is shown to be movable, but generally, all general terminals 100 can be assumed to be movable. General terminal 100 performs packet communication according to the frame configuration shown in Figure 3, and transmits general information (information packet 46) from general terminal 100a to general terminal 100b. The specific packet communication procedure has already been explained in Figures 3, 4, 5, (E), (O), (Ka), (Ki), (Ku), (Ke), etc. Furthermore, when general terminal 100c enters the communication range, general terminal 100b similarly performs packet communication with general terminal 100c, transmitting the general information it had stored. General terminal 100c stores the general information received from general terminal 100b internally (storage unit 17).

[0074] Subsequently, general terminal 100c moves and, after entering the communication range with general terminal 100d, transmits general information to general terminal 100d (see Figure 6). In this way, when the terminal device 100 moves, the information packet 6 can be relayed over a wide area.

[0075] (S) Specific example 2 Figure 7 shows another concrete example of an actual implemented configuration (Example 2), in which one priority terminal 100e holds important information, and multiple general terminals 100a, 100b, and 100c are deployed over a wide area. The operation of this configuration will be explained below. General terminals 100a and 100b are located within a distance from each other that allows them to communicate. On the other hand, general terminal 100c is located at a distance that prevents it from communicating with either general terminal 100a or general terminal 100b. Priority terminal 100e is moving, and if it is in a position close to general terminals 100a and 100b, it can only communicate with general terminals 100a and 100b. Also, if priority terminal 100e is in a position close to general terminal 100c, it can only communicate with general terminal 100c.

[0076] Thus, in this specific example 2, we describe an example in which only the priority terminal 100e moves. However, the mobility of the general terminals 100a, 100b, 100c and the priority terminal 100e is specific to this specific example 2, and in reality, it is possible to configure all terminals 100 to be mobile. In this specific example 2, the priority terminal 100e first acquires priority channel access rights in the priority access section 42 described in the frame configuration explained in Figure 3. Next, the priority terminal 100e can preferentially transmit important information (shown as (1) in Figure 7) to the general terminals 100a and 100b (see Figure 7). Meanwhile, the general terminal 100b receives the index packet 44 in the priority access section of the priority terminal 100e according to the frame configuration in Figure 3, and then receives important information (information packet 46). Furthermore, the general terminal 100b then transmits general information (information packet 46) to the priority terminal 100e. The general information is indicated as general information (2) in Figure 7.

[0077] Next, the priority terminal 100e moves to a range where it can communicate with the general terminal 100c. The device enters the communication range (Figure 7). When the priority terminal 100e detects that it has entered the communication range with the general terminal 100c, it transmits the important information stored in the priority terminal 100e and the general information received from the general terminal 100b to the general terminal 100c via packet communication. The general terminal 100c stores the received important information and general information internally. The information stored in the priority terminal 100e (important information, general information) refers to the information (important information, general information) stored in the memory unit 17 of the priority terminal 100e. Here, general information may be, for example, general information received from the general terminal 100b.

[0078] Furthermore, the operation by which the priority terminal 100e transmits information to the general terminal 100c is the same as the operation described above: it transmits an index packet 44, and in response, the general terminal 100c transmits an information request packet 50 containing the information it wants. The priority terminal 100e then transmits an information packet 46 containing the desired information (important information or general information), which the general terminal 100c receives. The general terminal 100c receives these information packets 46 and stores the desired information (important information, general information) in its internal storage unit 17. Thus, in this specific example 2, the priority terminal (100e) holding important information is configured to have preferential access to the priority access section 42, so to speak, important information can be assigned to the priority access section 42. Therefore, information transmitted by the priority terminal 100e can be given priority, and the arrival of important information can be achieved with priority (over general information).

[0079] D. Summary (1) Action and Effects A distinctive feature of the method described in this embodiment is the inclusion of an index packet 44 and an information request packet 50, in addition to the information packet 46 for transmitting information. By providing such an index packet 44 and an information request packet 50, it is possible to reduce the unnecessary redundant relaying of large information packets. Another distinctive feature of this embodiment is the provision of a priority access period. By providing this priority access period, it becomes possible to relay highly important information preferentially. Furthermore, it is expected to improve the efficiency of information sharing through terminal-to-terminal communication without the use of central control.

[0080] (2) An example of use in which the effects of the present invention can be demonstrated In areas with underdeveloped infrastructure, this system can be effectively used to collect necessary management data and to disseminate market data and advice from agricultural cooperatives by communicating between sensor-equipped terminals that monitor crops and pesticides, terminals mounted on agricultural vehicles, and terminals mounted on agricultural cooperative vehicles. In such uses, the information disseminated by agricultural cooperatives is considered to be of public importance and therefore highly important, making this embodiment of the system highly effective. Furthermore, it can be effectively used for information sharing and advertising within a region, including in moving vehicles. Among the shared information, public information or emergency information is considered highly important and can be treated as important information.

[0081] (3) Furthermore, the embodiments described above are merely examples of means for realizing the present invention, and should be modified or changed as appropriate depending on the configuration of the apparatus to which the present invention is applied and various conditions, and the present invention is not limited to the embodiments described above. [Explanation of symbols]

[0082] 10 terminals 10a, 100e priority terminals 10b, 100a, 100b, 100c, 100d General terminals 10c Authorized Terminal 12 antennas 14. Wireless Communication Section 16. Data Management Department 17 Memory section 18 Frame Management Department 20 Sensor device 22 cameras 24 Smartphones 40, 40a, 40b sync slots 42, 42a, 42b Priority access sections 44, 44a, 44b, 44c, 44d Index Packets 46, 46-1, 46-2, 46-n, 46-#1, 46-#2, 46-n1, 46-n2 information packets 48 Information packet distribution section 50, 50a, 50b, 50c, 50d Information Request Packets P1 Priority Terminal t1, t2, t3 time U1, U2 General Terminals

Claims

1. A terminal device used for inter-terminal communication, A wireless communication unit that communicates with other terminals, The data management unit manages the information packets that are the target of communication, A storage unit for storing the aforementioned information packets, A frame management unit that manages the frames for inter-terminal communication, Equipped with, The aforementioned frame includes a priority access section, The data management unit selects a transmittable information packet by referring to the storage unit, creates an index packet corresponding to the selected information packet, and sends the created index packet to the wireless communication unit. If designated as a priority terminal by the application layer, the frame management unit instructs the wireless communication unit to transmit the index packet in the entire frame section, including the priority access section. When designated as a general terminal from the application layer, the frame management unit instructs the wireless communication unit to transmit the index packet only in sections other than the priority access section. The terminal device is characterized in that the wireless communication unit transmits the received index packet.

2. A terminal according to claim 1, The wireless communication unit receives an information request packet transmitted from the other terminal and sends the information request packet to the data management unit. The data management unit retrieves an information packet corresponding to the transmitted information request packet from the storage unit, and sends the retrieved information packet to the wireless communication unit. The aforementioned wireless communication unit is characterized by transmitting the received information packet by broadcast.

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