JP2007006437A - Communication system, communication control method, communication control apparatus, and communication control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system which can ensure throughput among terminals by reducing influences of a hidden terminal while sharing a communication medium among terminals in a communication network in which no control station is present. <P>SOLUTION: Each terminal is provided with a time sync unit for performing a process of establishing time sync with a destination terminal, using time sync information for establishing time synchronization relating to access timing to a communication medium, and a communication monitor unit for monitoring time sync information in communication between other terminals, wherein the time sync information in communication between other terminals, which is obtained by the communication monitor unit, is transmitted to a terminal which is different from the other terminals and establishes no time synchronization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication system, a communication control method, a communication control apparatus, and a communication control program, and in particular, a plurality of communication networks in a communication network in which no control station exists or access control to a communication medium is not performed even if it exists. The present invention relates to establishment of time synchronization between terminals and communication control of synchronization data.

  In general, when performing data communication while sharing a communication medium among a plurality of terminal stations, each terminal station senses the communication medium prior to data packet transmission, and the communication medium is in use (channel busy). If it is confirmed, data packet transmission is refrained, and if the communication medium is unused (channel idle), the access control method for transmitting the data packet is called CSMA (Carrier Sense Multiple Access). . This method is used in a wireless LAN (Local Area Network) or a power line communication method.

  Among the plurality of terminal stations that perform data communication, the two terminal stations exist so far apart that the signals cannot reach each other directly, or the signals are blocked between the two terminal stations. There may be a situation where the other terminal station cannot directly receive the signal transmitted by one terminal station, such as the presence of an obstacle to be transmitted. The two terminal stations in such a situation are considered to be hidden terminals from each other. Call.

  Since the carrier sense described above does not function effectively between hidden terminals, when one terminal station is transmitting a data packet, the other terminal station may start transmitting the data packet. However, there is a problem that data packets collide with each other at an intermediate position between the terminal stations, and normal reception cannot be performed.

In order to solve the above problems, conventionally, before transmitting a data packet, a transmission request packet (hereinafter referred to as “RTS”) / transmission path release request packet (hereinafter referred to as “CTS”) is established between communicating terminal stations. And a method for securing a communication medium is defined (see Non-Patent Document 1).
This method of securing a communication medium using RTS and CTS is effective as a solution to the problem that occurs between hidden terminals.

  However, since the RTS / CTS is a command that prohibits transmission of terminal stations other than the transmission destination in the first place, depending on the network configuration, a terminal pole that cannot be communicated in a chain is generated, and data transmission efficiency is reduced. Sometimes.

  In order to solve this problem, some conventional communication systems relay RTS and CTS to other terminals prior to data packet communication (see Patent Document 1). More specifically, when each wireless station is in a network configuration as shown in FIG. 1, when performing communication using RTS / CTS as shown in FIG. Each terminal station relays and controls the RTS including the issued source and destination addresses as RTSR (RTS Repeat), and simultaneously performs a plurality of communications in a relationship in which no data packet collision occurs in the communication network. It can be established.

  Further, in general, an access control method in which each terminal station shares one frequency while being exchanged for a short time and transmits data is referred to as TDMA (Time Division Multiple Access). This method is used in PDC (Personal Digital Cellular) and PHS (Personal Handyphone System), which are second-generation mobile phone systems.

  In this TDMA system, the time assigned to each terminal station, called a slot, and the access timing to the communication medium are controlled by the base station, so that the terminal station communicates within the slot assigned to each terminal station. The medium can be occupied and the throughput can be guaranteed. Therefore, in the TDMA system, unlike the CSMA system described above, there is no problem that the throughput decreases due to the hidden terminal.

  However, the TDMA system requires a control station for controlling the access time and timing to the communication medium. Since the installation of the control station leads to a complicated system and high cost, there is a problem that it is difficult to use the TDMA system as described above for communications that occur temporarily.

  As a conventional communication method for solving this problem, a slot that is the communication occupation time is constructed by dividing the access to the communication medium among a plurality of terminal stations, and then the reception slot corresponding to the amount of received data is surrounded. (See, for example, Patent Document 2), this method allows the base station to transmit synchronous data. Even if there is nothing, it can be performed only by an arbitrary terminal station.

  Hereinafter, the communication method of Patent Document 2 will be described in detail. In Patent Document 2, each terminal receives a beacon packet at a specific timing from other terminals in the vicinity, and constructs a transmission timing of the beacon packet and a slot included in the beacon packet. Based on necessary information, synchronize autonomously between terminals. FIG. 18 is a diagram illustrating the configuration of the frame period in the conventional communication method, and FIG. 19 is a diagram illustrating the position of the reception slot of each terminal in the conventional communication method.

  As shown in FIG. 18, in the frame period, a beacon slot (S0: BSLT) for transmitting a beacon at a predetermined timing and a data slot (S1 to S47: DSLT) for receiving data are arranged. A total of 48 pieces constitute a frame period (FLMP). The beacon slot (S0) in the frame period (FLMP) is provided as a position where each terminal transmits its beacon signal, and the data slots (S1 to S47) in the frame period (FLMP) When at least one reception slot (RSLT) is set so that the terminal does not collide with other terminals around the terminal, as shown in FIG. 19, the set reception slot (RSLT) It is provided to clearly indicate the position corresponding to the timing from the position where the beacon signal (BCN) is transmitted.

Each terminal adjusts the transmission position of the beacon packet and the position of the reception slot (RSLT) so as not to overlap with other terminals, and when data reception occurs in the reception slot of its own terminal, the received data By increasing / decreasing the receiving slot according to the amount, a slot is constructed without a base station, and synchronous data communication is performed. That is, each terminal discloses the reception slot (RSLT) of its own terminal in the beacon packet in advance, and when data communication is performed between terminals, the terminal that holds the data wants to transmit the communication partner. The terminal transmits the data using the reception slot (RSLT) disclosed by the terminal.
JP 2002-353975 A JP 2004-215073 A Wireless LAN Medium Access Control and Physical Layer Specifications, IEEE Std 802.11, Aug. 1999

  However, since the RTS and CTS relay procedures in each terminal station are unclear in the communication system shown in Patent Document 1 described above, it is difficult to use in a network in which the network configuration is dynamically changed. Further, since the communication medium secured by the RTS and CTS is temporary, there is a problem that it is impossible to guarantee the throughput of each terminal station throughout the network.

  Further, in the communication method of Patent Document 2 described above, each terminal station discloses only a reception slot (RSLT) that is a timing at which the terminal station wants to receive data. Since data transmission is performed using (RSLT), when there is a hidden terminal in the network, the reception slot (RSLT) is used by an unspecified terminal and data collision occurs. there is a possibility. Specifically, for example, when data communication is performed from the second terminal to the first terminal, the second terminal starts data transmission in a reception slot (RSLT) disclosed by the first terminal. However, at the same time, when the third terminal that is a hidden terminal with respect to the second terminal starts to transmit data to the first terminal in the same reception slot (RSLT), the second terminal And data from the third terminal will collide with each other. In other words, the communication method of Patent Document 2 has a problem that it cannot reliably and efficiently cope with communication from a plurality of terminals when there are hidden terminals.

  As a method for solving this problem, for example, the above-described RTS / CTS may be applied to the communication method of Patent Document 2. However, in this case, it is necessary to repeat the RTS and CTS procedures for each packet, which causes a reduction in throughput.

  Therefore, it is conceivable that the RTS / CTS procedure described above is performed not only for each packet but only for the start of data that is continuously transmitted. However, in this case, a bandwidth reservation procedure is eventually required. The feature of patent document 2 that data communication can be performed only by managing only the reception slot of the own terminal is lost.

  The present invention has been made in order to solve the above-described problem. In a communication network in which a control station does not exist or access control to the communication medium is not performed even if the control station exists, the communication medium is shared between terminals. Another object of the present invention is to provide a communication system, a communication control method, a communication control apparatus, and a communication control program that can guarantee throughput between terminals without being affected by hidden terminals.

  The communication system of the present invention is composed of a plurality of terminals and shares a communication medium for peer communication between terminals in a communication network that does not have a control station or does not control access to the communication medium even if it exists. In the communication system for performing data communication, each terminal performs processing for establishing time synchronization with a terminal that performs communication using time synchronization information for establishing time synchronization regarding access timing to the communication medium. A time synchronization unit that performs the communication, and a communication monitoring unit that monitors the time synchronization information transmitted and received in the communication between other terminals, and the time synchronization information in the communication between other terminals obtained by the communication monitoring unit It is to be transmitted to a terminal that is not time-synchronized.

  Accordingly, there is an effect that the influence of the hidden terminal can be reduced and the throughput can be guaranteed while the communication medium is shared between the terminals in the communication network in which the control station does not exist.

  Furthermore, in the communication system of the present invention, each terminal establishes time synchronization of its own terminal based on the time synchronization information obtained by the communication monitoring unit.

  Thereby, time synchronization can be easily established between terminals capable of direct communication.

  Furthermore, in the communication system according to the present invention, when the time synchronization information transmitted / received in communication between other terminals cannot be obtained, each terminal transmits the time synchronization information to start time synchronization. It is assumed that the establishment request is made.

  Thereby, even if a hidden terminal exists, time synchronization with the terminal can be established.

  Furthermore, in the communication system of the present invention, when each of the terminals has established time synchronization with a terminal different from the transmission source terminal of the time synchronization information at the time when the time synchronization information is received from another terminal. The time synchronization information corresponding to the time synchronization is returned to the transmission source terminal of the time synchronization information.

  Furthermore, in the communication system of the present invention, when each terminal receives synchronization time information established with another terminal as a response to the request for establishment of time synchronization, according to the received synchronization time information, The time synchronization of the own terminal is established.

  Thereby, time synchronization can be easily established in all terminals existing in the communication network.

  Furthermore, in the communication system of the present invention, the time synchronization information is at least one of communication time information, communication cycle information, time information that a terminal can transmit per one period of time synchronization, and transmission start time information. Included.

  Furthermore, in the communication system of the present invention, each terminal sets the time synchronization of the terminal on the basis of the time when the terminal receives the time synchronization information.

  The communication control method of the present invention is a time division multiple access method between arbitrary terminals in a communication network that includes a plurality of terminals and does not control the access to the communication medium even when there is no control station. In the communication control method of performing data communication using each terminal, each terminal uses its own terminal use slot representing a slot used by its own terminal, which indicates the use status of a slot as a communication time unit at an arbitrary timing during normal operation. And a slot notification step of notifying all other terminals existing in a position where the terminal can communicate directly with slot information composed of slots used by other terminals indicating slots used by terminals different from the own terminal Each time the slot information is notified from the other terminal, the slot information of all the plurality of terminals including the notified slot information is managed. Terminal information management step, and when performing data communication between the arbitrary terminals, using the slot information of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side , An empty slot detecting step for detecting unused empty slots, and a data communication step for performing data communication using the empty slots detected in the empty slot detecting step.

  As a result, in a communication network composed of multiple terminals, when performing data communication using the time division multiple access method, the communication bandwidth can be guaranteed without being affected by the hidden terminal, and the throughput can be more reliably guaranteed. Can do.

  Furthermore, in the communication control method of the present invention, the empty slot detection step is managed in the terminal information management step in the terminal on the data communication start side, and is all present at positions where direct communication with the communication start side terminal is possible. The terminal-use slot of the terminal is excluded from all slots, and the remaining slots are set as empty slots.

  Accordingly, the empty slot can be quickly detected based on the slot information of all of the plurality of terminals managed by the terminal, and the plurality of terminals can be prevented from using the same slot repeatedly.

  Further, in the communication control method of the present invention, when the empty slot detection step determines that there is a hidden terminal that the terminal on the data communication start side cannot directly communicate with, the terminal information management in the communication start side terminal The other terminal use slot of the terminal on the data communication response side managed in the step is excluded from the remaining slots, and the remaining slots are used as empty slots.

  Thereby, even if a hidden terminal exists, an empty slot can be detected based on slot information of all of the plurality of terminals managed by the terminal. As a result, the plurality of terminals can use the same slot repeatedly. Can be avoided.

  Furthermore, in the communication control method of the present invention, the empty slot detection step is managed in the terminal information management step in the terminal on the data communication start side, and is all present at positions where direct communication with the communication start side terminal is possible. The own terminal use slot and the other terminal use slot of this terminal are excluded from all slots, and the remaining slots are made empty slots.

  Accordingly, it is possible to reliably detect an empty slot with a simple procedure based on slot information of all the plurality of terminals managed by the terminal without determining whether or not there is a hidden terminal.

Also, the communication control method of the present invention comprises a plurality of terminals, and there is no control station, or even if it exists, access control to the communication medium is not performed. In the communication control method for performing data communication using the method, each terminal represents a slot that is not used by the own terminal, indicating the usage status of the slot that is a communication time unit at an arbitrary timing when operating at all times. Slot information composed of unused slots and slots not used by other terminals representing slots that are not used by terminals other than the own terminal are transferred to all other terminals that are present at positions where the terminal can directly communicate. A slot notifying step to be notified, and each time the slot information is notified from the other terminal, the plurality of terminals including the notified slot information A terminal information management step for managing lot information, and when performing data communication between the arbitrary terminals, the slots of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side This includes an empty slot detecting step for detecting unused empty slots using information, and a data communication step for performing data communication using the empty slots detected in the empty slot detecting step.
Thereby, in a communication network composed of a plurality of terminals, when performing data communication using the time division multiple access method, the communication band can be guaranteed without being affected by the hidden terminal.

  Furthermore, in the communication control method of the present invention, the terminal information management step associates and manages the unique IDs of the plurality of terminals and the slot information notified by each terminal.

  As a result, when a part of the communication network area overlaps with another communication network, or when a plurality of terminals in the communication network constitute a plurality of logical networks, between the terminals of the other communication networks Bandwidth guaranteed communication can be easily realized in data communication.

  Also, the communication control apparatus of the present invention comprises a plurality of terminals, and there is no control station, or even if it exists, access control to the communication medium is not performed. In the communication control device of each terminal that performs data communication using the method, the terminal that represents the slot used by the own terminal, representing the usage status of the slot, which is a unit of communication time, at any timing during normal operation Notifying all other terminals existing in a position where the terminal can directly communicate the slot information composed of the slot used and the slot used by another terminal representing a slot used by a terminal different from the terminal itself When the data communication performed between the arbitrary terminals is performed, the communication control unit that controls the data communication and the slot information are notified each time the slot information is notified from the other terminal. A terminal information management unit that manages the slot information of all of the plurality of terminals including the slot information, and the terminal information management unit of the terminal on the data communication start side when performing data communication between the arbitrary terminals. And an empty slot detecting unit that detects unused empty slots using the slot information of all of the plurality of terminals managed in (1).

  As a result, it is possible to reliably detect an empty slot, and in a communication network composed of a plurality of terminals, when performing data communication using the time division multiple access method, the communication band is not affected by the hidden terminal. Can be guaranteed.

Furthermore, in the communication control apparatus of the present invention, the empty slot detection unit is managed by the terminal information management unit of the terminal on the data communication start side, and is present at all positions where communication with the communication start side terminal is possible. The own terminal use slot of the terminal is excluded from all slots, and the remaining slots are vacant slots.
Thus, an empty slot can be quickly detected by a simple procedure based on slot information of all the plurality of terminals managed by the terminal, and the plurality of terminals are identical when performing data communication between the arbitrary terminals. It is possible to avoid redundant use of slots.

  In the communication control apparatus of the present invention, the empty slot detection unit determines that there is a hidden terminal that is a terminal that cannot be directly communicated with by the communication terminal that is a terminal with which the terminal performs data communication. In this case, the other terminal use slot in the communication terminal is excluded, and the remaining slot is set as an empty slot.

  Thereby, even if a hidden terminal exists, an empty slot can be detected by a simple procedure based on slot information of all the plurality of terminals managed by the terminal. As a result, when performing the data communication, The plurality of terminals can avoid using the same slot repeatedly.

  Furthermore, in the communication control apparatus of the present invention, the empty slot detection unit is managed by the terminal information management unit of the terminal on the data communication start side, and is present at all positions where communication with the communication start side terminal is possible. The own terminal use slot and the other terminal use slot of this terminal are excluded from all slots, and the remaining slots are made empty slots.

  Thereby, without determining whether there is a hidden terminal, based on the slot information of all of the plurality of terminals managed by the terminal, it is possible to reliably detect an empty slot in a simple procedure, As a result, it is possible to avoid a plurality of terminals from using the same slot repeatedly.

  Also, the communication control apparatus of the present invention comprises a plurality of terminals, and there is no control station, or even if it exists, access control to the communication medium is not performed. In the communication control device of each terminal that performs data communication using the method, the own terminal representing a slot that is not used by the own terminal, indicating the usage status of the slot, which is a communication time unit, at an arbitrary timing during normal operation Notifying all other terminals that are present in a position where the terminal can communicate directly with slot information composed of unused slots and slots not used by other terminals indicating slots that are not used by terminals other than the terminal itself In addition, when performing data communication between the arbitrary terminals, a communication control unit that controls the data communication and each time the slot information is notified from the other terminal The terminal information of the terminal on the data communication start side when performing data communication between the terminal information management unit that manages the slot information of all the plurality of terminals including the notified slot information and the arbitrary terminal An empty slot detection unit that detects an unused slot using the slot information of all the plurality of terminals managed by the management unit.

  Thereby, in a communication network composed of a plurality of terminals, when performing data communication using the time division multiple access method, the communication band can be guaranteed without being affected by the hidden terminal.

  Furthermore, in the communication control apparatus according to the present invention, the terminal information management unit manages the unique ID of the terminal in association with the slot information notified by each terminal.

  As a result, when a part of the communication network area overlaps with another communication network, or when a plurality of terminals in the communication network constitute a plurality of logical networks, between the terminals of the other communication networks Bandwidth guaranteed communication can be easily realized in data communication.

  The communication control program of the present invention comprises a plurality of terminals, and there is no control station, or even if it exists, access control to the communication medium is not performed. A communication control program included in each terminal for causing a computer to execute a communication control process for performing a data communication process using a method, and in a constant operation, the usage status of a slot, which is a unit of communication time, at an arbitrary timing The terminal directly communicates slot information including a slot used by the terminal representing a slot used by the terminal and a slot used by another terminal representing a slot used by a terminal different from the terminal. A slot notification step for notifying all other terminals existing in a possible position, and whenever the slot information is notified from the other terminal, A terminal information management step for managing the slot information of all of the plurality of terminals including known slot information, and when performing data communication between the arbitrary terminals, the terminal in the terminal on the data communication start side Using the slot information of all of the plurality of terminals managed in the information management step, an empty slot detection step for detecting an unused slot, and using the empty slot detected in the empty slot detection step And a data communication step for performing data communication.

  As a result, in a communication network composed of a plurality of terminals, when performing data communication using the time division multiple access method, the communication band can be guaranteed without being affected by the hidden terminal, so that the throughput is more reliably guaranteed. be able to.

  The communication control program of the present invention comprises a plurality of terminals, and there is no control station, or even if it exists, access control to the communication medium is not performed. A communication control program included in each terminal for causing a computer to execute a communication control process for performing a data communication process using a method, and in a constant operation, the usage status of a slot, which is a unit of communication time, at an arbitrary timing Slot information composed of an unused slot representing a slot not used by the own terminal and an unused slot representing another terminal not used by a terminal different from the own terminal. A slot notification step for notifying all other terminals existing in a position where direct communication is possible, and the slot information is notified from the other terminals. Each of the plurality of terminals including the notified slot information, and a terminal information management step for managing the slot information, and when performing data communication between the arbitrary terminals, An empty slot detection step for detecting an unused slot using the slot information of all the plurality of terminals managed in the terminal information management step in the terminal, and an empty space detected in the empty slot detection step And a data communication step of performing data communication using the slot.

  As a result, in a communication network composed of a plurality of terminals, when performing data communication using the time division multiple access method, the communication band can be guaranteed without being affected by the hidden terminal, so that the throughput is more reliably guaranteed. Can do.

  According to the communication system of the present invention, a communication medium for performing peer communication between terminals in a communication network that includes a plurality of terminals and does not have a control station or does not control access to the communication medium even if it exists. In a communication system that shares data and communicates data, each terminal establishes time synchronization with a synchronous communication destination terminal using time synchronization information for establishing time synchronization regarding access timing to a communication medium A time synchronization unit for performing the processing to perform, and a communication monitoring unit for monitoring the time synchronization information in communication between other terminals, and the time synchronization information in communication between other terminals obtained by the communication monitoring unit Since it is transmitted to terminals that are not time-synchronized, a communication medium between terminals is used in a communication network that does not have a control station. Also hidden to reduce the influence of the terminal while having an effect that can be guaranteed throughput.

  Further, according to the communication control method, communication control apparatus, and communication control program of the present invention, when each terminal is always in operation, the terminal can directly communicate slot information indicating the usage status of the slot as a communication time unit. A slot notifying step for notifying all other terminals existing at the location, and a terminal information managing step for managing the slot information for all of the plurality of terminals including the slot information notified in the slot notifying step. Including the slot information of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side when performing data communication between the arbitrary terminals, An empty slot detection step to be detected and an empty slot detected in the empty slot detection step Data communication step for performing data communication, and when communicating data between arbitrary terminals, it is possible to reliably detect unused slots with a simple procedure, and to reduce the communication bandwidth without being affected by hidden terminals. As a result, there is an effect that the throughput can be reliably guaranteed.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In this case, the synchronous data is a digitized signal that requires real-time property and isochronous property such as a moving image signal or an audio signal, or an accumulated data thereof. Commands other than data that occur asynchronously such as command notifications and inquiries. Further, the communication system composed of a plurality of terminals may be wired or wireless, but here it is assumed to be a wireless communication system, and data communication is performed using the same frequency band for connection to a communication medium. However, the description here assumes that IEEE802.11b having a transmission rate of 11 Mbps is used.

(Embodiment 1)
In the first embodiment, in a communication system that includes a plurality of terminals and communicates data by sharing a communication medium in order to perform peer-to-peer communication between terminals in a communication network in which no control station exists, Including the time synchronization information for establishing the time synchronization regarding the access timing to the communication medium in the packet transmitted and received between the terminals, and establishing the time synchronization according to the time synchronization information between the terminals, By forming pseudo slots for synchronous communication between terminals, throughput between terminals is guaranteed.

FIG. 1 is a network configuration diagram of a radio communication system according to Embodiment 1 of the present invention.
In FIG. 1, reference numerals 101 to 104 denote communication terminals having unique IDs, terminal A, terminal B, terminal C, and terminal D, respectively. Here, each terminal 101-104 is distributed on the same space which is a communication medium. And the broken lines 105-108 in FIG. 1 represent the communication ranges of the terminals A101, B102, C103, and D104, respectively. In FIG. 1, each terminal cannot directly communicate with all other terminals, which means that a hidden terminal exists for each terminal. Specifically, the signal transmitted by the terminal A101 cannot be directly received by the terminal C103 and the terminal D104, the signal transmitted by the terminal B102 cannot be directly received by the terminal D104, and the signal transmitted by the terminal C103 is the terminal A101. The signal transmitted by the terminal D104 cannot be received by the terminal A101 and the terminal B102.

Next, an internal configuration in each of the terminals A to D will be described with reference to FIG.
FIG. 2 is a block diagram showing a configuration of a part related to data communication of each terminal of the wireless communication system according to the first embodiment of the present invention.

  2, each of the terminals A to D includes an upper layer interface 201, a time synchronization unit 202, a lower layer interface 203, a transmission processing unit 204, a communication monitoring unit 205, and a reception processing unit 206.

  The upper interface 201 is an interface to an upper layer of a communication terminal (not shown), and is connected to, for example, a block that handles image and audio data such as a PC and AV equipment. The time synchronization unit 202 handles time synchronization information for establishing time synchronization related to access timing to the communication medium, and includes a time synchronization period timer 202a therein. The lower layer interface 203 is an interface to a lower layer in each of the terminals A to D, and is connected to, for example, a block that transmits / receives data according to the IEEE 802.11b system.

  The transmission processing unit 204 generates a transmission request from an upper layer received via the upper layer interface 201 or a transmission request generated inside the terminal as a packet, and notifies the lower layer via the lower layer interface 203. Is. The detailed configuration of the generated packet will be described later.

  The communication monitoring unit 205 monitors the time synchronization information in communication between other terminals included in data received via the lower layer interface 203. Details of the time synchronization information will be described later.

  The reception processing unit 206 notifies the packet received from the lower layer via the lower layer interface 203 to the upper layer via the upper layer interface 201 or processes the packet inside the terminal. Receive and process. A detailed configuration of a packet processed inside the terminal will be described later.

  Next, referring to FIG. 3, a synchronous communication request packet (FIG. (A)) and a synchronous communication response exchanged to establish time synchronization between a plurality of terminals in the wireless communication system according to the first embodiment. The configuration of the packet (FIG. (B)) will be described.

  As shown in FIG. 3, the fields of the structure of the synchronous communication request packet 310 and the synchronous communication response packet 320 are divided according to the contents, and time synchronization related to the access timing to the communication medium is established in each packet. Time synchronization information necessary for this is included.

  As shown in FIG. 3A, the synchronous communication request packet 310 includes a transmission destination terminal ID field 301, a transmission source terminal ID field 302, a time synchronization period field 303, a slot time field 304, an offset field 305, and a slot number. The synchronous communication response packet 320 includes a transmission destination terminal ID field 301, a transmission source terminal ID field 302, a time synchronization, as shown in FIG. 3B, and is composed of a field 306, a reservation field 307, and a packet type field 309. It consists of a period field 303, a slot time field 304, an offset field 305, a slot number field 306, a status field 308, and a packet type field 309. The fields 301 to 306 and 309 are common fields common to both the synchronous communication request packet 310 and the synchronous communication response packet 320.

  Hereinafter, each field will be described in detail. The transmission destination terminal ID field 301 is an address field indicating a transmission destination terminal, and the transmission source terminal ID field 302 is an address field indicating a transmission source terminal. The time synchronization period field 303 is a field indicating information of a time synchronization period for establishing time synchronization, and the slot time field 304 further partitions the period specified in the time synchronization period field 303. The offset field 305 is a field indicating an elapsed time from a time synchronization period set when the synchronous communication request packet 310 or the synchronous communication response packet 320 is transmitted, and the slot number A field 306 indicates information on a slot number to be used in the synchronous communication request packet 310, and information on a slot number requested to be used in the synchronous communication request packet 310 or information on a slot number currently used in the synchronous communication response packet 320. Field showing A. In the first embodiment, the slot number is notified by mapping the slot number to each bit of the field 306. For example, when the synchronization slot to be communicated is slot 1, “1” is set to bit number 0 in the slot number field 306 (“00000000 00000001”), and when the synchronization slot to be communicated is slot 2, “1” is set to bit number 1 of the slot number field 306 (“00000000 00000010”). Note that the method of notifying the slot number is not limited to that described above, and any method may be used as long as each terminal can recognize the slot number.

  The packet type field 309 is a packet ID field indicating a packet type, and the value of this field identifies whether the packet is a synchronous communication request packet 310 or a synchronous communication response packet 320.

  The reserved field 307 is a field that exists only in the synchronous communication request packet 310 and is a field that exists in order to match the packet configuration with the synchronous communication response packet 320, and therefore does not include information. The status field 308 is a field that indicates a response result to a synchronization establishment request issued from a certain terminal between communication terminals. Examples of the response result include “success”, “failure”, “already A status code having a meaning such as “used slot” or “synchronization already established” is set.

  The time synchronization information described above is composed of the time synchronization period field 303, the slot time field 304, the offset field 305, and the slot number field 306 in the packets 310 and 320. This is used to form a pseudo slot shown in FIG.

  In FIG. 3, for convenience, the lengths of the fields included in the synchronous communication request packet 310 and the synchronous communication response packet 320 are displayed. Here, the communication destination terminal ID field 301 and the transmission source terminal ID field 302 are 6 bytes, the time synchronization period field 303, the slot time field 304, the offset field 305, the slot number field 306, the reservation field 307, the status. The field 308 and the packet type field 309 are each 2 bytes. Note that the length of each field displayed here is set for convenience and is not limited to this.

  Next, in order to guarantee the throughput of each terminal A to D in the wireless communication system of the first embodiment, it is established based on the time synchronization information included in the synchronous communication request packet and the synchronous communication response packet described above. The pseudo slot will be described.

  FIG. 4 is a conceptual diagram of slots established by time synchronization information in the wireless communication system according to the first embodiment. It is assumed that time elapses in the direction of the arrow in the figure.

  As shown in FIG. 4, in the first embodiment, there are three slots for communicating synchronous data (hereinafter simply referred to as “synchronous slots”), and slots for transmitting asynchronous data (hereinafter referred to as “synchronous slots”). This is simply referred to as an “asynchronous slot”), and one is arranged, and this arrangement is periodically repeated to form a slot.

  Here, the time synchronization period in FIG. 4 is based on the period information set in the time synchronization period field 303 in the synchronous communication request packet 310 or the synchronous communication response packet 320 described above, and the slot in FIG. The time is based on time information set in the slot time field 304 of the packets 310 and 320. The offset in FIG. 4 is based on the elapsed time information from the time synchronization period set in the offset field 305 of the packets 310 and 320. With this offset value, the time synchronization information is set at an arbitrary time. Each terminal that has received the packet including it can determine the start of the time synchronization period.

  In the first embodiment, the slot time is smaller than the value of the time synchronization period, and the slot time that can be secured within the time synchronization period is smaller than the synchronization slot and the slot synchronization time. This time is defined as an asynchronous slot. Each slot is assigned a conceptual number. The first slot in the cycle is slot 1, and the next slot is the time axis direction regardless of whether the slot is a synchronous slot or an asynchronous slot. Set serial numbers incremented by 1. Then, the number of the slot next to the last slot, that is, the first slot of the next period is set as slot 1 again, and the serial number incremented by 1 in the time axis direction is set again from the slot after the slot 1 again. To do. Note that the configuration of the slot shown in FIG. 4 is an example, and the present invention is not limited to this.

  Next, in the wireless communication system according to the first embodiment, a procedure for establishing time synchronization by terminals A to D will be described with reference to FIG.

  FIG. 5 is an explanatory diagram showing a procedure for establishing time synchronization regarding access timing to a communication medium in the wireless communication system according to the first embodiment of the present invention. In FIG. 5, a horizontal arrow indicates time. It is assumed that time elapses in the right direction. In FIG. 5, when communication is performed by each unit of each of the terminals A to D, a transmission source and a transmission destination are represented by up and down arrows, and packet types to be transmitted and received are shown along with up and down arrows.

  First, when a request for synchronous communication with the terminal B102 occurs in the terminal A101, the time synchronization unit 202 of the terminal A101 transmits time synchronization information for establishing time synchronization between the terminals A and B. The transmission processing unit 204 creates a synchronous communication request packet A including the time synchronization information, and transmits it to the terminal B102. Here, the synchronous communication request packet A created by the terminal A 101 is, for example, “terminal B” in the transmission destination terminal ID field 301, “terminal A” in the transmission destination terminal ID field 302, and “ 1000 milliseconds, “200 milliseconds” in the slot time field 304, “0” in the offset field 305, “slot 1” in the slot number field 306, and “synchronous communication request packet” in the packet type field 309. Set each. Note that the time synchronization information (corresponding to the fields 303 to 306) shown here is a value set for convenience, and is not limited to this.

  The terminal B102 that has received the synchronous communication request packet A as described above processes the packet received by the reception processing unit 206, and then outputs it to the communication monitoring unit 205. When the communication monitoring unit 205 receives the synchronous communication request packet B, the communication monitoring unit 205 outputs the time synchronization information included in the packet B to the time synchronization unit 202. When receiving the time synchronization information, the time synchronization unit 202 determines that the terminal B itself has not yet established time synchronization and may operate according to the time synchronization information included in the synchronous communication request packet A. A time synchronization information indicating permission of synchronous communication between A is output to the transmission processing unit 204, and the transmission processing unit 204 returns a synchronous communication response packet B including time synchronization information indicating permission of synchronous communication. Create and send to terminal A101. Here, the “time synchronization information meaning permission of synchronous communication” means the same time synchronization information as the time synchronization information included in the received synchronous communication request packet A. That is, the synchronous communication response packet B created by the terminal B102 indicates “terminal A” in the transmission destination terminal ID field 301, “terminal B” in the transmission source ID field 302, and “successful establishment of synchronization” in the status field 308. "Information" is set in the packet type field 309, and "synchronous communication response packet" is set. In the fields 303 to 306 indicating time synchronization information, the same information as the synchronous communication request packet A received from the terminal A101 is set. . On the other hand, when the time synchronization unit 202 that has received the time synchronization information determines that the terminal B itself has already established time synchronization and should not operate according to the time synchronization information included in the synchronous communication request packet A, A synchronous communication response packet not permitting synchronous communication is output to terminal A101. Details of the synchronous communication response packet not permitting synchronous communication will be described later.

  Here, it is assumed that the terminal B determines that the terminal B itself may operate according to the time synchronization information included in the synchronous communication request packet 303.

  In the terminal B that has transmitted the synchronous communication response packet B described above, the time synchronization unit 202 sets the time synchronization period timer 202a simultaneously with the completion of the transmission. As a result, the terminal B establishes time synchronization with the time t1 as the time synchronization period start position.

  Also, in the terminal A101 that has received the time synchronization response packet B, the time synchronization unit 202 sets the time synchronization period timer 202a immediately after the reception processing unit 206 completes reception of the packet. As a result, the terminal A101 establishes time synchronization with the time point t1 as the period start position of the time synchronization, and the terminal A101 can perform synchronous communication with the terminal B102 using the slot 1.

  By the way, the terminal C103 exists in addition to the terminal A101 in the radio wave reachable range of the terminal B102. Accordingly, the terminal C103 can receive the synchronous communication response packet B transmitted from the terminal B102 to the terminal A101.

  In the terminal C that has received the packet B, the communication monitoring unit 205 checks the address set in the transmission destination terminal ID field 301 of the received packet B, and transmits it to its own terminal (here, the terminal C). Judge whether it was done. At this time, normally, in the case of a packet transmitted to a specific terminal other than its own terminal, the packet addressed to the other terminal is discarded, but the time synchronization information is included in the packet addressed to the other terminal. In this case, the time synchronization information is extracted and output to the time synchronization unit 202, and then the packet is discarded.

  The time synchronization unit 202 that has received the time synchronization information from the communication monitoring unit 205 determines whether or not the terminal C itself has already established time synchronization. If the synchronization has not yet been established, the received time Establish time synchronization using the synchronization information. That is, the terminal C itself calculates the start time of the next time synchronization period based on the timing at which the packet B including the time synchronization information is received, the time synchronization period in the time synchronization information, and the offset value. The time synchronization period timer 202a inside the terminal C is set at the obtained timing. Here, since the offset value is 0, the terminal C is set when the packet B is received. As a result, the terminal C103 can establish time synchronization with the time point t1 as the time synchronization period start position.

  By the above procedure, not only the terminals A101 and B102 that perform synchronous communication, but also the terminal C103 that has received the synchronous communication response packet B establishes time synchronization. When the terminal C103 communicates with other terminals after the time synchronization is established, the terminal C103 recognizes the slot that is currently used, and therefore does not transmit during the period of the slot that is being used. There is no interference.

  On the other hand, the terminal D104 is a hidden terminal of the terminal A101 and the terminal B102, and is present at a position where neither the time synchronization request packet A nor the time synchronization response packet B can be received. Cannot establish time synchronization as a time synchronization period start position, and at that time, the terminal D104 does not establish time synchronization with other terminals, and the time synchronization unit 202 of the terminal D104 We recognize that there is no synchronous communication between terminals.

  Here, when the terminal D104 tries to start synchronous communication addressed to the terminal C103, the time synchronization unit 202 of the terminal D104 creates the synchronous communication request packet D and transmits it to the terminal C103. At this time, in the synchronous communication request packet D transmitted from the terminal D to the terminal C, the destination terminal ID field 301 is “terminal C”, the transmission source terminal ID field is “terminal D”, and the packet type field 309 is “synchronous communication”. The time synchronization information included in the packet D is different from that established between the terminals A, B, and C. For example, the time synchronization period field 303 is “500 milliseconds”. ”, The slot time field 304 is set to“ 50 milliseconds ”, the offset field 305 is set to“ 0 ”, and the slot number field 306 is set to“ slot 1 ”. Note that the value of the time synchronization information shown here is set for convenience and is not limited thereto.

  When the communication monitoring unit 205 of the terminal C103 receives the communication synchronization request packet D as described above, the time synchronization unit 202 of the terminal C103 has already established time synchronization. The time synchronization information held by the unit 202 (that is, the time synchronization period is “100 milliseconds”, the slot time is “200 milliseconds”, the slot number is “slot 1 currently used”, and the offset is “terminal C”. Is set to “terminal D” in the destination terminal ID field 301 and “terminal C in the source terminal ID field 302”. “, A value indicating that the terminal C has already established time synchronization” is set in the status field 308. The communication response packet C, and back to the terminal D104 addressed.

  When the communication monitoring unit 205 of the terminal D104 receives the synchronous communication response packet C, the communication monitoring unit 205 recognizes from the status field 308 that synchronous communication cannot be performed and is included in the packet C. The time synchronization information is notified to the time synchronization unit 202 of the terminal D. Then, the time synchronization unit 202 performs an operation of establishing time synchronization based on the time synchronization information notified from the communication monitoring unit 205. That is, terminal D104 calculates the start time of the next time synchronization period based on the timing at which synchronous communication response packet C is received, the time synchronization period in the time synchronization information included in the packet, and the offset value. The time synchronization period timer 202a inside the terminal D is set at the obtained timing. As a result, the terminal D104 can establish time synchronization with the time point t1 as the time synchronization period start position.

  Accordingly, the time synchronization established by the terminal D104 is the same as the time synchronization established between the terminals A101, B102, and C103, and the terminal D104 recognizes that the slot 1 is currently used. As a result, when the terminal D104 communicates with another terminal after establishing time synchronization, the terminal D104 avoids the currently used slot number, and thus interferes with the synchronous communication performed by the other terminal. There is nothing.

  The wireless communication system establishes time synchronization between the terminals A to D according to the above procedure, and each of the terminals A to D including the hidden terminal secures a slot when communicating to transmit data between the terminals. To do.

  As described above, in the wireless communication system according to the first embodiment, each terminal transmits time synchronization information included in a synchronous communication response packet transmitted / received in communication between other terminals, or a synchronous communication request packet transmitted by each terminal. Based on the time synchronization information set in (2), time synchronization between terminals is established, and when each terminal performs communication between terminals, a pseudo slot is formed based on the shared time synchronization information. Since the allocated slot is secured and communication between terminals is performed, even if the network configuration is dynamically changed in a wireless network without a control station, it is hidden while sharing a communication medium between terminals. The influence of the terminal can be reduced and the throughput can be guaranteed.

  In the first embodiment, the procedure for establishing time synchronization on the basis of the synchronous communication request packet and the synchronous communication response packet is shown. However, by including the time synchronous information in the synchronous communication data, the synchronous communication request Time synchronization can be established with a terminal that has not received the packet and the synchronous communication response packet.

(Embodiment 2)
By the way, in the first embodiment, when performing synchronous communication, each terminal cannot know the slot currently used by all the terminals existing in the network. Collisions can occur. In the second embodiment shown below, when performing synchronous communication between terminals in the wireless network, a collision of synchronous communication due to overlapping use of slots is prevented in the network, and throughput between terminals is further increased. A communication control method that can be reliably guaranteed will be described.

  FIG. 6 is a diagram illustrating an arrangement example of terminals including a communication control device in Embodiment 2 of the present invention. In FIG. 6, 601 to 604 are terminals having unique IDs of terminal E, terminal F, terminal G, and terminal H, respectively, and the terminals E601 to H604 are distributed in the same space as a communication medium. Show. And the broken line 605 in FIG. 6 has shown the common communication range of each terminal 601-604, and since each terminal E601-H604 can communicate directly with all the other terminals, a hidden terminal is It means not existing.

  In the communication control method according to the second embodiment, an access method to a communication medium is adopted in which each terminal communicates with other surrounding terminals while considering the influence of each other.

  FIG. 7 is a diagram illustrating a configuration example of a period of access control by the time division multiplexing method in the communication control method according to the second embodiment of the present invention. As shown in FIG. 7, in the second embodiment, four synchronous slots and one asynchronous slot are arranged, and the time division multiplexing method is realized by periodically repeating this arrangement. Here, the asynchronous slot is the last slot in the cycle.

  In the second embodiment, as in the first embodiment, a conceptual number is set for each slot, and the first slot in the cycle is defined as slot 1. Then, a serial number that is sequentially increased by 1 in the time axis direction is set for the next slot regardless of whether the slot is a synchronous slot or an asynchronous slot. Then, the number of the slot next to slot 5 at the end of the period, that is, the first slot of the next period is again set as slot 1, and the serial number incremented by 1 in the time axis direction again from the slot after the slot 1 again. Set.

  Note that the access methods or parameters related to the time division multiplex method shown here are set for convenience and are not limited to these. Furthermore, in the above description, the configuration of the synchronous slot and the asynchronous slot in the cycle is determined in advance, but the configuration in the cycle can be dynamically changed by negotiation with other terminals. Also good.

Next, the configuration of a packet transmitted and received by each terminal E601 to H604 will be described.
In the second embodiment, each of the terminals E601 to H604 is directly connected at an arbitrary timing at an arbitrary timing in order to realize access control by a time division multiplexing method of an arbitrary terminal existing in the communication network. A slot information communication packet including slot information indicating a slot usage status, which is a communication time unit, is distributed to all other terminals existing in a communicable position. And at the time of synchronous communication of data, the data packet containing data is delivered.

  Each time each terminal of the second embodiment receives the slot information from another terminal, the slot usage of all the plurality of terminals existing in the network including the received slot information is included in the terminal. The situation is managed in association with the ID of each terminal.

  When each terminal performs synchronous communication of data, an empty slot that can be used for synchronous communication is detected based on the slot usage status of all the terminals managed by the terminal on the communication start side.

  As a result, in the second embodiment, even if there is no control station, it is possible to prevent another terminal from using the same slot as that used when performing data communication between arbitrary terminals. The communication band for data communication can always be guaranteed.

  First, the slot information notification packet will be described. FIG. 8 is a diagram illustrating a configuration example of a slot information notification packet including slot information according to the second embodiment. In FIG. 8, a slot information notification packet 800 includes slot information necessary for realizing access control by the time division multiplexing method.

  The packet structure is divided into fields depending on the contents. For example, the packet type field 801, the transmission destination terminal ID field 802, the transmission source terminal ID field 803, the slot number field 804, the period field 805, the slot number field 806, and the own terminal A usage field 807 and an other terminal usage field 809 are included.

  The packet type field 801 is a field for identifying a packet type, that is, a slot information packet, the transmission destination terminal ID field 802 is an address field indicating a transmission destination terminal, and a transmission source terminal ID field 803 Is an address field indicating a transmission source terminal, and a slot number field 804 is a field indicating a slot number in which the slot information notification packet is transmitted from the transmission source terminal. A period field 805 is a field representing period information in time division multiplexing, and a slot number field 806 is a field representing the number of slots in time division multiplexing. The own terminal use slot field 807 is a field indicating the slot number used by each terminal, and the other terminal use slot field 808 is a slot used by a terminal different from the own terminal in each terminal. It is a field indicating a number. The self terminal use slot field 807 and the other terminal use slot field 808 described above will be described later. The slot information includes the period 305, the slot number 306, the own terminal use slot 307, and the other terminal use slot 308.

  In FIG. 8, the length of each piece of information included in the slot information notification packet 800 is displayed for convenience. Here, the packet type field 801 is 2 bytes, the destination terminal ID field 802 is 6 bytes, the source terminal ID field 803 is 6 bytes, the slot number field 804, the period field 805, and the slot number field 806. The own terminal use slot field 807 and the other terminal use slot field 808 are each 2 bytes.

  Note that the length of each field related to slot information such as the period field 805, the slot number field 806, the own terminal use slot field 807, and the other terminal use slot field 808 is changed according to the parameter of the access control by the time division multiplexing method. You may be made to do. The length of each field displayed here is set for convenience, and is not limited to the displayed value.

  Here, the own terminal use slot field 807 and the other terminal use slot field 808 will be described in detail. The own terminal use slot field 807 and the other terminal use slot field 808 set the slot used by each terminal.

  That is, the slot number used by the own terminal is set in the own terminal use slot field 807, and the slot number used by another terminal other than the own terminal is set in the other terminal use slot field 808.

  Here, the slot number used is mapped to each bit of 2 bytes indicating the own terminal use slot field 807 and the other terminal use slot field 808 to notify the use slot of each terminal. To.

  For example, when the own terminal uses the slot number 1, the bit number 0 of the own terminal use slot field 807 is set to “1” (“00000000 00000001”) and is located around the own terminal. When another terminal uses slot number 2, bit number 1 of other terminal use slot field 808 is set to “1” (“00000000 00000010”). Note that the method of expressing the own terminal use slot field or other terminal use slot field may be any method as long as the use status of each terminal and each slot is known, and is not limited to the method shown here. .

Next, the configuration of a data packet that performs synchronous communication between terminals will be described.
FIG. 9 is a diagram illustrating a configuration example of a data packet 900 including data according to the second embodiment. In FIG. 9, a data packet 900 includes a packet type field 901, a transmission destination terminal ID field 902, a transmission source terminal ID field 903, a slot number field 904, and a payload 905.

  The packet type field 901 is a field for identifying a packet type, that is, a data packet, the transmission destination terminal ID field 902 is an address field indicating the transmission destination terminal, and the transmission source terminal ID field 903 is It is an address field representing a transmission source terminal. A slot number field 904 is a field indicating a slot number for transmitting the data packet by the transmission source terminal, and a data body for transmission / reception is set in the payload 905.

  In FIG. 9, the length of each piece of information included in the data packet 900 is displayed for convenience. Here, the packet type field 901 is 2 bytes, the destination terminal ID field 902 is 6 bytes, the source terminal ID field 903 is 6 bytes, the slot number field 904 is 2 bytes, and the payload 905 is 0. It has an arbitrary length of bytes or more. Note that the length of each field displayed here is set for convenience and is not limited to the displayed value.

  Furthermore, in the second embodiment, as a procedure for acquiring a synchronization slot used when performing the data communication, a slot communication confirmation request packet and slot communication are performed between the data communication start terminal and the data communication response terminal. It is assumed that after exchanging the acknowledgment packet, data communication is performed using the synchronization slot. Also, in order to release the acquired slot, such as when data communication by synchronous communication is completed, the data communication start terminal transmits a slot release packet to the data communication response terminal, thereby releasing the acquired slot. To do.

  The slot communication confirmation request packet, the slot communication confirmation response packet, and the slot release packet are packets that are neither the slot information notification packet 800 nor the data packet 900, and the configuration of each packet is the packet type field, the transmission In addition to the destination terminal ID field and the source terminal ID field, it has slot information necessary for communication. Further, in addition to the information, the slot communication confirmation request packet has information indicating a slot number to be acquired, and the slot communication confirmation response packet has information indicating a result of the acquisition request.

  The slot acquisition procedure and the release procedure may be any procedure and packet configuration as long as they can be recognized between the terminals of the data communication start terminal and the data communication response terminal or at terminals located around the terminals. The method is not limited.

Next, a configuration example of the communication control device included in each terminal in Embodiment 2 of the present invention will be described.
FIG. 10 is a block diagram showing the configuration of the communication control apparatus according to Embodiment 1 of the present invention. A communication control apparatus 1001 shown in FIG. 10 shows a configuration of a part that controls packet communication included in each of the terminals E601 to H604 in FIG. 6. The communication control apparatus 1001 includes an interface 1002, a transmission / reception buffer 1003, A central control unit 1004, a packet generation unit 1005, a packet analysis unit 1006, a communication unit 1007, a slot management unit 1008, and a terminal information management unit 1009 are provided.

  The interface 1002 exchanges various types of information between a device (not shown) connected to the communication control apparatus 1001 and the transmission / reception buffer 1003. Devices connected to the communication control apparatus 1001 include, for example, PCs and AV devices, and the exchanged information includes, for example, digitized synchronization data such as moving image signals or audio signals. is there.

  The communication unit 1007 is connected to a space that is a communication medium, and performs data transmission and reception processing. The communication unit 1007 includes a transmission unit 1007a and a reception unit 1007b physically or logically, and transmits and receives data, respectively. Examples of the communication unit 1007 include IEEE802.11b and Bluetooth.

  In the transmission / reception buffer 1003, data received from a device (not shown) connected to the communication control apparatus 1001 via the interface 1002, transmission data generated in the communication control apparatus 1001, and data received from the communication unit 1007 are stored. Used for temporary storage.

  The terminal information management unit 1009 manages the slot information of all the plurality of terminals in the network including slot information received from other terminals at an arbitrary timing in association with the terminal ID of each terminal. As a result, it is possible to manage the slot usage status in all the terminals existing in the communication network while updating the latest information. The terminal information management unit 509 may manage not only the slot information but also information related to packet communication status such as the number of packet transmission / reception and the number of packet errors.

  The packet generation unit 1005 performs a process of adding additional information for the communication control device 1001 to data transmitted via the transmission unit 1007a in the communication unit 1007. For example, when transmitting the data packet 900, the packet type field 901, the transmission destination terminal ID field 902, the transmission source terminal ID field 903, the slot number field 904, and the payload 905 shown in FIG. Perform packetization processing.

  The packet analysis unit 1006 analyzes the contents of the packet received via the reception unit 1007b in the communication unit 1007, and performs processing for extracting necessary information from the packet. For example, when the packet analysis unit 1006 receives the slot information notification packet 800 shown in FIG. 8, first, it is confirmed from the packet type field 801 that the received packet is a slot information notification packet. The destination terminal ID field 802, the source terminal ID field 803, the slot number field 804, the period field 805, the slot number field 806, the own terminal use slot 807, and the other terminal use slot 308 are extracted and passed through the central control unit 1004. Then, slot information (period field 805, slot number field 806, own terminal use slot field 807, and other terminal use slot field 808) is set in terminal information management section 1009 and slot management section 1008. When the data packet 900 shown in FIG. 9 is received, first, similarly, it is confirmed from the packet type field 901 that the received packet is a data packet, and the destination terminal ID field 902 in the packet is confirmed. The information is extracted from each of the transmission source terminal ID field 903, the slot number field 904, and the payload 905, and the data is set in the transmission / reception buffer 1003 via the central control unit 1004.

  The slot management unit 1008 has a slot information notification timer 1008a, a slot timer 1008b, and a slot number management counter 1008c, and autonomously updates the current slot number. Specifically, when the slot timer 1008b expires, the slot number management counter 508c is incremented, and the slot number at the current time is updated. After incrementing to the last slot number (here, slot 5), the slot number is updated again from the first value (slot 1). The length of the slot timer 1008b is a value obtained by dividing the value of the period field 805 by the value of the slot number field 1006 in the slot information.

  When the slot number indicated in the slot number management counter 1008c indicates a communicable slot number acquired by the terminal itself, the central control unit 1004 is prompted to transmit data, while the central control unit 504 receives slot information. When a packet including slot information such as the notification packet 800 is received, processing for correcting the expiration timing of the slot timer 1008b is performed.

  Further, when this timer expires, the slot information notification timer 1008a sets the slot information of its own terminal in the slot information notification packet 800 to the central control unit 1004, and performs a process to work to start transmission. The length of the slot information notification timer 1008a is arbitrarily set.

  The central control unit 1004 includes a communication control unit 1004a that performs a series of processing in data communication of the entire apparatus 1001 and a series of processing in time division multiplexing, and an empty slot detection unit 1004b that detects an empty slot.

  Note that each of an interface 1002, a transmission / reception buffer 1003, a central control unit 1004, a packet generation unit 1005, a packet analysis unit 1006, a communication unit 1007, a slot management unit 1008, and a terminal information management unit 1009 constituting the communication control apparatus 1001 is provided. The configuration function may be connected to the central control unit 1004 as hardware, or may be realized as a program that can be read and executed by the central control unit 1004.

  Next, the operation of the communication control apparatus 1001 described above will be described. In the second embodiment, it is assumed that slot information notification packet 800 is transmitted immediately after the slot number is switched (that is, the start timing of each slot). In this way, the receiving terminal side determines the timing at which the slot information notification packet 800 is received as the slot start position, and determines the current slot number based on the information held in the slot number field 804 in the slot information notification packet 800. It is possible to obtain access control between terminals by time division multiplexing. If the slot information notification packet 800 is provided with a time offset from the start position of the slot, the time division multiplexing method can be used between terminals even if the packet 800 is transmitted / received at a timing other than the slot start timing. It is possible to realize the access control by. Note that any method can be used as a method for realizing access control by the time division multiplexing method between terminals as long as the start timing of the slot can be shared between terminals, and is limited to the method shown here. Is not to be done.

  Also, here, it is assumed that the slot information notification packet 800 transmission interval, slot period, and slot number held in the slot management unit 1008 are 3000 milliseconds, 100 milliseconds, and five, respectively. As shown in FIG. 8, slots 1 to 4 are synchronous slots and slot 5 is an asynchronous slot.

  It should be noted that the transmission interval of the slot information notification packet, the slot period, the value of the number of slots, etc., which are parameters for realizing the above-described time division multiplexing method, are the communication status of the packet, the transmission within the communication control device 1001, Since this parameter depends on the reception processing time and the timer accuracy required for the communication control apparatus 1001, the present invention is not limited to this.

  Further, since the asynchronously generated packet transmitted to each terminal is transmitted using an arbitrary asynchronous slot, the slot information notification packet 800 is transmitted using slot 5 in the second embodiment. Although it is assumed that the slot information notification packet 800 can be regarded as periodically transmitted synchronization data, the slot information notification packet 800 is transmitted in an unused synchronization slot or a synchronization slot acquired by the terminal itself. Also good.

  First, the operation of the terminal for realizing the time division multiple access method will be described using the flowchart of FIG. This operation is controlled by the communication control unit 1004a of the central control unit 1004. In addition, FIG. (A) shows the initial operation of the terminal immediately after power-on or reset, and FIG. (B) shows the steady operation other than the initial state.

  As shown in FIG. 11A, the terminal in the initial state immediately after power-on or immediately after resetting performs a scanning operation (step S101) and collects information on other terminals around the terminal. The scan operation is an operation of collecting packets transmitted by other terminals in the vicinity and acquiring information on the communication network (for example, slot information for realizing the time division multiplexing method) from the collected packets.

  If slot information can be acquired as a result of the scanning operation (step S102), various parameters included in the acquired slot information are extracted, and the terminal information management unit 1009 and the slot management unit 1008 of the terminal itself are extracted. After the information is updated and managed (step S103), the slot information notification timer 1008a in the slot management unit 1008 is started to start time division multiplexing access control (step S105).

  If the slot information could not be acquired in step S102, it is determined that there is no other terminal around at the present time, and the slot information of the own terminal is notified to the other terminal (step S104). Then, the access control of the time division multiplexing method is started by starting the slot information notification timer 1008a in the slot management unit 1008 (step S105). Note that the slot information acquisition operation after the scan operation described above should be performed for a slot information notification packet transmission interval (in this case, 3000 msec) which is held in the slot management unit 1008.

  If the terminal in steady operation other than the initial state expires in the slot information notification timer 1008a in the slot management unit 1008 as shown in FIG. 11B (step S201), the slot management unit of its own terminal Information regarding time division multiplexing is set in the slot information notification packet 800 from 1008 and transmitted immediately after the start of the next asynchronous slot (slot 5) (step S202). If the timing of switching to a slot number that can be used by the terminal is the same as the timing of expiration of the slot information notification timer 1008a, the slot information notification packet 800 is transmitted immediately after the expiration of the slot information notification timer 1008a. Also good.

  On the other hand, when the terminal receives slot information from another terminal during the steady operation (step S203), various parameters are extracted from the slot information, and the terminal information management unit 1009 and the slot management unit 1008 in the own terminal Information is updated and managed (step S204). In this way, every time slot information from another terminal is acquired, the information held in the terminal information management unit 1009 and the slot management unit 1009 is updated and managed again, so that the communication between terminals autonomously. The mismatch of slot information can be prevented.

  In the above description, the scan operation is performed in the initial state immediately after power-on or immediately after reset. However, the scan operation described above may be periodically repeated even in a steady operation other than the initial state. In this way, since each terminal can regularly exchange slot information, it is possible to prevent mismatch of slot information between terminals. Conversely, in the above description, when the slot information notification timer 1008a expires during normal operation, the slot information of its own terminal is always notified. However, in a certain terminal, the slot information notification packet 800 is received from another terminal. Even if the slot information notification timer 1008a expires within the same period of the slot, the slot information notification packet 800 may not be transmitted from the own terminal. In this way, it is possible to limit an increase in traffic between terminals.

  Next, the operation of the terminal for detecting an empty slot in the communication control method will be described using the flowchart of FIG. This operation is performed by a terminal on the data communication start side before performing data communication, and the control is performed by an empty slot detection unit 1004b in the central control unit 1004 of the terminal.

  First, based on the information of a plurality of terminals managed by the terminal information management unit 1009 of the terminal on the data communication start side, all terminals that can directly communicate with the terminal from all slots 1 to 5 use themselves. Slot, that is, the own terminal use slot is excluded (step S301).

  Next, a hidden terminal is detected (step S302), and if there is no hidden terminal, the slot remaining at this point is determined as an empty slot (step S303).

  On the other hand, if the communication network has a hidden terminal in step S303, the other terminal use slot of the terminal on the data communication response side is further excluded (step S304). At this time, if there is a remaining slot (step S305), the slot is set as an empty slot (step S306). If there is no remaining slot (step S305), it is determined that there is no empty slot (step S307).

  Here, the hidden terminal detection method in step S302 includes a method of detecting that there is a hidden terminal when only one of the packets can be received in a series of packet exchange sequences, and a slot information notification transmitted by another terminal. A well-known method such as a method of detecting that there is a hidden terminal when a packet other than a slot number directly used by another terminal use slot is notified is used, and will not be described in detail here.

  In the above-described empty slot detection method, it is determined whether or not there is a hidden terminal in the communication network, but data communication is performed from all slots 1 to 5 without determining whether or not there is a hidden terminal. Exclude all slots used by the terminal and other terminals from all terminals that can be directly communicated by the initiating terminal. If there are any remaining slots, the slot is designated as an empty slot. You may make it judge that it is not.

Hereinafter, an operation sequence between terminals will be described with reference to FIGS. 13 and 14.
FIG. 13 is a sequence diagram showing a communication procedure of synchronous data in the second embodiment. In FIG. 13, it is assumed that time elapses downward, and when communication is performed by each terminal, the transmission source and the transmission destination are represented by left and right arrows, and are transmitted and received together with the left and right arrows. Indicates the packet name or event name. FIG. 14 is a diagram showing slot information managed by the terminal information management unit in the terminal at a certain point of time in the synchronization data communication procedure shown in FIG.

  (Step S400) The terminal that started the operation first (for example, the terminal that is first turned on) performs the scanning operation, but the other terminal is not operating yet, so the slot information of the other terminal cannot be acquired, As shown in FIG. 11A, a slot information notification packet 800 is transmitted to notify the slot information of the terminal itself. Thereafter, the other terminals that have started the operation sequentially set the terminal information of the terminal information management unit 1009 and the slot management unit 1008 in its own terminal, as shown in FIG. To do.

  The terminal that started the operation first and the other terminals that started the operation after that start the slot information notification timer 1008a in the slot management unit 1008 in each terminal, and start the time division multiplexing access control. Thereafter, each terminal performs a steady operation as shown in FIG. In FIG. 13, the slot information notification packet 800 is illustrated as being transmitted and received between adjacent terminals. However, in the network configuration shown in FIG. 6, there is no hidden terminal, so a certain terminal transmits it. It is assumed that the slot information notification packet 800 has been received by all other terminals.

  It is assumed that the synchronous communication is started between the terminal E and the terminal F using the synchronous slot from the state where each terminal is not performing the synchronous communication. Hereinafter, an operation sequence between the terminals E and F will be described.

  There is no hidden terminal in the slot information of all the terminals managed by the terminal information management unit 1009 in both terminals E and F at this time, and all the terminals including the terminals E and F are synchronized slots. No slot number is displayed because no is used. FIG. 14A is a diagram showing information managed by the terminal information management unit 1009 in both terminals E and F at this time.

  (Step S401) In order to reserve a synchronization slot to be used when data communication is performed with the terminal F, the terminal E detects an empty slot.

  As shown in FIG. 14, the empty slots are detected by removing the own terminal use slots of all the terminals F to H existing at positions where the terminal E can directly communicate from all the slots 1 to 5, and then the hidden terminal Determine if it exists. At this time, since each terminal is in a state of not performing synchronous communication, no synchronization slot is removed, and since there is no hidden terminal in the first embodiment, all slots are free. It is judged.

  (Step S402) Next, the terminal E transmits a slot communication confirmation request packet for requesting synchronous communication to the terminal F using the slot. Here, it is assumed that a slot having a smaller slot number is selected from the available slots and used for communication. Accordingly, the terminal E transmits a slot 1 communication confirmation request packet requesting synchronous communication using the slot 1 to the terminal F.

  (Step S403) The terminal F that has received the slot 1 communication confirmation request packet confirms the slot information of all the terminals held in the terminal information management unit 1009 in the terminal F, and determines whether or not the slot 1 is free. judge. In the slot information of all the terminals managed by the terminal information management unit 1009 in the terminal F at this time, as shown in FIG. 14A, the slot number is displayed for both the own terminal use slot and the other terminal use slot. Therefore, it is determined that slot 1 is free, and a slot 1 communication confirmation response packet is sent back as a response that synchronous communication using slot 1 is possible, and is managed by terminal information management unit 1009 in terminal F. Of the slot information of all the plurality of terminals, the slot 1 is displayed in the own terminal use slot of each of the terminals E and F. FIG. 14B is a diagram showing information managed by the terminal information management unit 1009 in the terminal F described above.

  (Step S404) The terminal E that has received the slot 1 communication confirmation response packet selects the slot used by the terminal E of the terminal E among the slot information of all the terminals managed by the terminal information management unit 1009 in the terminal E. After performing update management for displaying slot 1, data communication is performed with terminal F using slot 1.

  (Steps S405 to S406) After that, for example, if the slot information notification timer 1008a of the terminal F expires before other terminals, the terminal F transmits the slot information notification packet 800 shown in FIG. , G, H. At this time, in the slot information notification packet 800 transmitted from the terminal F, the packet type field 801 has “ID indicating slot notification packet”, the destination terminal ID field 802 is “broadcast terminal ID” indicating all terminals, The terminal ID field 803 is “terminal F ID”, the slot number field 804 is “slot 5” indicating an asynchronous slot, the period field 805 is “100” indicating 100 msec, the slot number field 306 is “5”, In the terminal use slot field 807, bit 0 is “1”, the other bits 1 to 15 are “0” (“00000000 00000001”), and the other terminal use slot field 808 is all bits 0 to 15 are “0” ( “00000000 00000000”).

  (Step S407) Since the slot information notification packet 800 transmitted by the terminal F is received by all the other terminals E, G, and H, each terminal E, G, H receives the above-described slot information notification packet 800. Various information is extracted, and the information managed by the slot management unit 1008 and the terminal information management unit 1009 in each terminal E, G, H is updated and managed. Note that the terminal E that is performing synchronous data communication with the terminal F using the slot 1 has already been updated and managed in the terminal information management unit 1009 in step S404. Don't do it. On the other hand, the terminals H and G extract information from the slot information notification packet 800 received from the terminal F, and of the slot information of all the terminals managed by the terminal information management unit 1009 of each terminal G and H, the terminal The slot number 1 is displayed in the F own terminal slot. FIG. 14C is a diagram showing information managed by the terminal information management unit 1009 of each of the terminals G and H at this time.

  (Steps S408 to S410) Thereafter, for example, if the slot information notification timer 1008a of the terminal E has expired, the terminal A transmits the slot information notification packet 800 similar to the terminal F described above to all the other terminals F to H. Of the terminals F, G, and H that have received the slot information notification packet 800 from the terminal E and are terminals other than the terminal F that is performing synchronous communication with the terminal E using the slot 1 G and H set slot number 1 in the own terminal use slot of terminal E in terminal information management section 1009 inside each terminal. FIG. 14D is a diagram showing slot information managed by the terminal information management unit 1009 of each of the terminals G and H at this time.

  (Steps S411 to S413) After that, if the slot information notification timer 1008a of a terminal that is not performing synchronous communication, for example, the terminal G, has expired, the terminal G transmits the slot information notification packet 800 to all other terminals E, Send to F, H. At this time, the slot information notification packet 800 transmitted from the terminal G has a packet type field 801 “ID indicating slot information notification packet”, a destination terminal ID field 802 “broadcast terminal ID” indicating all terminals, and transmission. The original terminal ID field 803 is “terminal G ID”, the slot number field 804 is “slot 5” indicating an asynchronous slot, the period field 805 is “100” indicating 100 msec, the slot number field 806 is “5”, In the own terminal use slot field 807, all bits 0 to 15 are “0” (“00000000 00000000”), in the other terminal use slot field 808, bit 0 is “1”, and other bits 1 to 15 are “0”. "(" 00000000 00000001 ") The

  Of the other terminals E, F, and H that have received the slot information notification packet 800 from the terminal G, the terminal H that is a terminal other than the terminals E and F that are performing synchronous communication using the slot 1 Of the slot information of all the plurality of terminals managed by the internal terminal information management unit 1009, the slot number 1 is displayed in the other terminal use slot of the terminal G. FIG. 14E is a diagram illustrating information managed by the terminal information management unit 1009 of the terminal H at this time. Since this display shows that terminals other than the terminal G are using the slot 1, when there is a terminal that starts communication using the synchronization slot with the terminal G (for example, the terminal H), at least the slot 1 is used. It is possible to avoid and select another slot.

  As described above, according to the second embodiment, the communication control apparatus 1001 included in each terminal has the slot management unit 1008 and the terminal information management unit 1009, and each terminal has an arbitrary timing set in advance. Then, the slot information including the own terminal use slot used by the own terminal and the other terminal use slot used by another terminal different from the own terminal is transmitted, and the slot information is transmitted from the other terminal. When received, the information of the terminal information management unit in its own terminal is updated and managed including the received slot information, so that multiple terminals in the network where the control station does not exist duplicately use the same slot Thus, data communication can be prevented, and time division multiplex connection between a plurality of terminals can be efficiently realized.

  In the second embodiment, each time each terminal acquires the slot information notification packet 800 transmitted from another terminal, the terminal information management unit 1009 information in each terminal including the acquired slot information is acquired. For example, every time a packet including slot information such as a slot communication confirmation request packet or a slot communication confirmation response packet is received, the terminal information management including information included in the request or response packet is received. The information in the unit 1009 may be updated and managed.

  In the second embodiment, when there are a plurality of unused unused slots, the slot having the smallest slot number is selected and used for synchronous communication. Select a slot with a large slot number, randomly select it to avoid duplicate selection between terminals, select a slot that has been used less frequently, The selection method may be any method, such as selecting a slot with less communication error due to the selection of the communication status.

  Further, in the second embodiment, the slot information is included in the slot information notification packet 800 and transmitted to each terminal. However, the slot information is reported to the slot information notification such as a data packet 900, for example. It is also possible to set a packet other than the packet 800 and transmit it to each terminal. In this way, when the terminal that has not received the slot information notification packet 800 receives another packet that is frequently transmitted / received to / from the terminal other than the slot information notification packet 800, Since slot information can be collected, it is possible to reliably prevent the mismatch of slot information between terminals.

  Furthermore, packet configurations such as the data packet 900 and the slot information notification packet 800 transmitted and received in the communication control method according to the second embodiment are not limited to the above-described components. For example, every time data is transmitted. Number, a sequence number for performing packet dropout and order control on the data communication response side, a fragment number necessary for dividing and combining the data packet 900, and a data communication response side for detecting data errors An ECC code (Error Correcting C) for correcting an error such as an EDC code (Error Detection Code) such as a CRC code (Cyclic Redundancy Check), which is an error detection code, or a Hamming code (Hamming Code). de, etc. and communication status error correction code), according to the transmission accuracy of the data request to the communication control apparatus of the second embodiment may be added as additional information.

  In the second embodiment, the information on the slot used in the terminal is distributed as the slot information indicating the slot usage status. However, the slot information is not used as the slot information instead of the slot used. The information on the used slots may be distributed. In this way, since either slot information or unused slot information may be described as slot information in the slot information notification packet 800, it is necessary for the terminal receiving this notification packet to distinguish between these. is there. For example, a method for determining in advance which one to use in the communication network, a method for preparing another area by increasing the packet length of the packet including the slot information, or a local terminal use slot 807, another terminal use slot There is a method of setting information for identification in the slot information notification packet 800 such as using each unused bit (for example, most significant bit) of 808.

(Embodiment 3)
Hereinafter, in Embodiment 3, a case will be described in which unused slots that are not used by each terminal are displayed and distributed as slot information in the slot information notification packet 800. Moreover, in this Embodiment 3, it demonstrates as what has a hidden terminal.

  FIG. 15 is a diagram illustrating an arrangement example of terminals that mean the communication control device according to the third embodiment of the present invention. In FIG. 15, reference numerals 1501 to 1504 denote terminals having unique IDs of terminal I, terminal J, terminal K, and terminal L, respectively. The terminals I1501 to L1504 are distributed in the same space as a communication medium. Show. 15 indicate the communicable ranges of the terminal I1501, the terminal J1502, the terminal K1503, and the terminal L1504, respectively. Unlike the second embodiment described above, each terminal is different from the other in this embodiment. This means that it is not possible to communicate directly with all terminals, and there are hidden terminals for each terminal. Specifically, the terminal I1501 cannot directly communicate with the terminal K1503 and the terminal L1504, the terminal J1502 cannot directly communicate with the terminal L1504, and the terminal K1503 can directly communicate with the terminal I1501. The terminal L1504 cannot directly communicate with the terminal I1501 and the terminal J1502.

  In each terminal of the third embodiment, a method for controlling access to the communication medium, parameters related to synchronization slots, configurations of packets to be transmitted and received (slot information notification packet 800, data packet 900, etc.), The configuration of the communication control device provided is the same as that of the second embodiment described above.

  However, in Embodiment 3, it is assumed that unused slots of the own and other terminals are displayed in the slot information notification packet 800. Therefore, the slot information notification packet 800 ′ transmitted / received in the third embodiment is not used in its own terminal use slot field 807 and other terminal use slot field 808 in FIG. A terminal unused slot field 808 'is displayed.

  In the third embodiment, in order to indicate that an unused slot is displayed in the slot information notification packet 800, the terminal slot of the own terminal unused slot field 807 ′ and the other terminal unused slot field 808 ′ are displayed. The upper bit is set to “1”. Note that the method of expressing the unused slots of the own terminal or other terminals may be any method as long as the unused status of each terminal and each slot is known, and is not limited to the method shown here.

  However, the terminal information management unit 1009 does not manage the unused slots of the own and other terminals in each terminal, but manages the used slots of the own and other terminals in each terminal as in the second embodiment. . As described above, even if the display method of the slot information on the packet is changed, the empty slot detection method described in the second embodiment can be used as long as the information display method managed in the apparatus 1001 is matched. effective.

  Hereinafter, an operation sequence between terminals according to the third embodiment will be described with reference to FIG. In FIG. 16, it is assumed that time elapses downward, and when communication is performed by each terminal, the transmission source and the transmission destination are represented by left and right arrows, and are transmitted and received together with the left and right arrows. Indicates the packet name or event name.

  (Step S500) Each terminal starts time-division multiplexing access control by transmitting and receiving slot information notification packets to and from each other as in step S400 of FIG.

  Assume that synchronous communication is started between the terminal I and the terminal J using a synchronization slot from a state in which each terminal does not perform synchronous communication. Hereinafter, an operation sequence between the terminals I and J will be described.

  Since all terminals including the terminals I and J do not use the synchronization slot in the slot information of all the terminals managed by the terminal information management unit 1009 in both terminals I and J at this time, the slot No number is displayed.

  (Step S501) In order to reserve a synchronization slot to be used when data communication is performed with the terminal J, the terminal I detects an empty slot.

  In the detection of the empty slot, it is determined whether or not there is a hidden terminal after removing the own terminal use slots of all terminals with which the terminal I can communicate directly from all slots. In the third embodiment, although there are hidden terminals, it is determined that all slots are empty because other peripheral terminals including the own terminal do not use the synchronization slot.

  (Step S502) Next, the terminal I transmits a slot communication confirmation request packet for requesting synchronous communication to the terminal J. Here, as in the second embodiment, it is assumed that a slot having a smaller slot number is selected from the available slots and used for synchronous communication. Accordingly, the terminal I transmits a slot 1 communication confirmation request packet for requesting synchronous communication using the slot 1 to the terminal J.

  (Step S503) The terminal J that has received the slot 1 communication confirmation request packet confirms the slot information of all the plurality of terminals held in the terminal information management unit 1009 in the terminal J, and determines whether or not the slot 1 is free. judge. At this time, no slot number is displayed in the slot information of all the terminals managed by the terminal information management unit 1009 in the terminal J. Therefore, the terminal J determines that the slot 1 is free, returns a slot 1 communication confirmation response packet that responds that the synchronous communication using the slot 1 is possible, and the terminal information management unit in the terminal J Of the slot information of all the plurality of terminals managed in 1009, slot 1 is displayed in the own terminal use slot of each of terminals I and J.

  (Step S 504) The terminal I that has received the slot 1 communication confirmation response packet sets the terminal I's own terminal use slot in the slot information of all the terminals managed by the terminal information management unit 1009 in the terminal I. After performing update management for displaying slot 1, data communication is performed with terminal J using slot 1.

  (Steps S505 to S506) After that, for example, if the slot information notification timer 1008a of the terminal J has expired, the terminal J transmits the slot information notification packet 800 ′ to all terminals existing in the communication range 1506 of the terminal J (here Then, the data is transmitted to terminals I and K). At this time, in the slot information notification packet 800 ′ transmitted from the terminal J, the packet type field 801 indicates “slot notification packet ID”, the transmission destination terminal ID field 802 indicates “broadcast terminal ID” indicating all terminals, and transmission. The original terminal ID field 803 is “terminal J ID”, the slot number field 804 is “slot 5” indicating an asynchronous slot, the period field 805 is “100” indicating 100 msec, and the slot number field 806 is “5”. , The terminal unused slot 307 ′ is bits 1, 2, and 3 and the most significant bit 15 is “1”, the other bits are “0” (“10000000 000011010”), and the other terminal unused slot 308 ′ is Bits 0, 1, 2, 3, and 15 are "1", and other bits are "0" ("100 Is a 0000 00001111 ").

  (Step S507) Since the slot information notification packet 800 ′ transmitted from the terminal J is received by the terminals I and K which are terminals capable of directly communicating with the terminal J, the terminals I and K transmit the above-described slot information notification. Information is extracted from the packet 800 ′, and information managed by the slot management unit 1008 and the terminal information management unit 1009 in each of the terminals I and K is updated and managed. Note that since the terminal I that is performing synchronous communication with the terminal J using the slot 1 has already updated and managed new information in the terminal information management unit 509 in step S504, the information is not managed here. The terminal K extracts information from the slot information notification packet 800 ′ received from the terminal J, and uses the terminal J's own terminal among the slot information of all the multiple terminals managed by the terminal information management unit 1009 in the terminal K. Slot number 1 is displayed in the slot.

  (Steps S508 to S509) After that, for example, if the slot information notification timer 1008a of the terminal I has expired, the terminal I transmits a slot information notification packet 800 'similar to the above to all terminals. Here, only terminal J, which is a terminal that can communicate with terminal I, receives slot information notification packet 800 ′ from terminal I. However, since the terminal J is performing synchronous communication with the terminal I using the slot 1, the terminal information management unit 1009 in the terminal J is not updated.

  (Steps S <b> 510 to S <b> 512) Further, after this, for example, when the slot information notification timer 1008 a of the terminal not performing synchronous communication, for example, the terminal K expires, the terminal K transmits the slot information notification packet 800 ′ within the communication range 1507 of the terminal K. Are transmitted to all terminals (terminals J and L in this case). At this time, the slot information notification packet 800 ′ transmitted from the terminal K has a packet type field 801 “ID indicating a slot information notification packet”, a destination terminal ID field 802 “broadcast terminal ID” indicating all terminals, The source terminal ID field 803 is “terminal K ID”, the slot number field 804 is “slot 5” indicating an asynchronous slot, the period field 805 is “100” indicating 100 msec, and the slot number field 806 is “5”. , The own terminal unused slot field 807 ′ is “0” for bits 0, 1, 2, 3, 15 and “0” (“10000000 000011111”) for other bits, and the unused slot 308 ′ for other terminals is Bits 1, 2, 3, and 15 are “1”, and other bits are “0” (“10” A 00000 00001110 ").

  Of the terminals J and L that have received the slot information notification packet 800 ′ from the terminal K, terminals other than the terminal J using the slot 1 (here, the terminal L) are the terminal information management unit 1009 inside the terminal J. The slot number 1 is displayed in the other terminal use slot of the terminal K among the slot information of all the plurality of terminals managed in the above. Since this display shows that terminals other than the terminal K are using the slot 1, if there is a terminal in which the terminal L starts communication using the synchronization slot with the terminal K, avoid at least the slot 1, Other slots can be selected.

  As described above, according to the third embodiment, the communication control apparatus 1001 included in each terminal has the slot management unit 1008 and the terminal information management unit 1009, and each terminal is set at an arbitrary timing set in advance. Then, the slot information including the own terminal slot used by the own terminal and the other terminal use slot used by another terminal different from the own terminal is transmitted and the slot information is received from the other terminal. In this case, since the information of the terminal information management unit 1009 in each terminal is updated and managed, in a network where there is no control station, there is no influence of hidden terminals, and a plurality of terminals in the network Data communication using the same slot in duplicate can be prevented, and time division multiplex connection between a plurality of terminals can be efficiently realized.

  In the third embodiment, the slot information notification packet 800 ′ displays the unused slot of its own and other terminals as slot information, and the terminal information management unit 1009 in the communication control apparatus 1001 displays the own and others in each terminal. Although the used slot of the terminal is managed, when the terminal information management unit 1009 manages the unused slot of its own other terminal in each terminal, the detection of an empty slot using the information of the terminal information management unit is performed. It becomes as follows.

  First, based on the slot information managed by the terminal information management unit 1009, it is described in common for slots not used by all terminals present at positions where direct communication is possible, that is, slots not used by the own terminal. Detect slot.

  Next, a hidden terminal is detected. If the network does not have a hidden terminal, the slot detected at this point is set as an empty slot. On the other hand, if the communication network has a hidden terminal, the slot described in the unused slot of the other terminal of the terminal on the data communication response side is set as an empty slot, and the empty slot is not described in the unused slot of the other terminal. Judge that there is no.

  Further, it is possible to directly communicate with the data communication start side terminal based on the slot information of all the plural terminals managed by the terminal information management unit 1009 on the data communication start side without determining whether or not there is a hidden terminal. Slots that are not used by all terminals in the location, that is, the common slots displayed in all unused slots of other terminal and unused slots of other terminals are detected, and the detected slots are detected as empty slots. Otherwise, it may be determined that there is no empty slot.

  The above-described communication control method according to the second or third embodiment can be realized by a program, and the communication control apparatus can be used as a recording medium in which the central control unit 1004 can record the program. It can also be configured to be separable from 1001. Further, the program recorded in the recording medium is read by a program reading device that is mounted on the communication control device 1001 or connected via the interface of the communication control device 1001 so that the central control unit 1004 can directly read the program. It may be configured as follows. Examples of the recording medium include magnetic tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks and hard disks, CD-ROMs (Compact Disk Read Only Memory), MO (Magneto Optical), DVD ( Disc system including optical disc such as Digital Versatile Disk (CD-R), Compact Disc Recordable (CD-R), IC card, card system of memory card, mask ROM (Read-Only Memory), EPROM (Erasable Programmable ROM), UV-EP (Ultra-Violet EPROM), EEPROM (Electrically Erasable P) ogrammable ROM), or the like can be used semiconductor memory system such as a flash ROM.

  Furthermore, according to the communication control method according to the second or third embodiment, even if the same communication network is used, the same slot can be used when the synchronous communication is performed at a sufficiently distant position, and the slot is effective. Can be used. However, it is determined that the slot used by the own terminal is being used by the other terminal by the scanning operation of each terminal or the reception of the slot information notification packets 800 and 800 ′ distributed from the other terminal. In such a case (for example, when the terminal moves), another empty slot is immediately detected so that the same slot is not used repeatedly.

  Furthermore, according to the communication control method according to the second or third embodiment of the present invention, the slot used by the directly communicable terminal is set as the slot used by the other terminal in the slot information notification packets 800 and 800 ′. Although the method of notifying the surroundings has been adopted, the slot used by the other terminal in the slot information notification packet notified by the surrounding terminal is set as the slot used by the other terminal of the other terminal in the slot information notification packet of FIG. You may make it add. This makes it possible to notify a wide range of slot numbers that are being used, so that the possibility of using the same slot within a range that does not affect communication can be reduced.

  Furthermore, according to the communication control method, the communication control device, and the communication control program according to the second or third embodiment, when a part of the communication network area overlaps with another communication network or hidden by the control station. Even if a communication network has no terminal, it is common to configure multiple logical networks by introducing network IDs (for example, network IDs are provided in packets and values are shared by the same logical network). In addition, the terminal is not involved in communication other than the communication network in which the terminal is participating, but even in such a case, the communication control method, the communication control apparatus, and the communication control program according to the present invention can be used. As a result, bandwidth-guaranteed communication between other communication networks can be easily realized. .

  A communication system, a communication control method, a communication control apparatus, and a communication control program according to the present invention guarantee throughput in a wireless network that does not have a control station or does not control access to a communication medium even if it exists. Since synchronous communication between terminals can be performed reliably, it is useful as a home network, an office network, or the like.

It is a network block diagram of the radio | wireless communications system by Embodiment 1 of this invention. It is a block diagram which shows the internal structure of each terminal of the radio | wireless communications system by Embodiment 1 of this invention. It is a figure which shows the structure of the synchronous communication request packet and synchronous communication response packet in the radio | wireless communications system by Embodiment 1 of this invention. It is a conceptual diagram of the slot established by the time synchronization information in the radio | wireless communications system by Embodiment 1 of this invention. It is explanatory drawing which shows the procedure until the time synchronization regarding the access timing to a communication medium is established in the radio | wireless communications system by Embodiment 1 of this invention. It is a figure showing the example of arrangement | positioning of the terminal which is a communication control apparatus by Embodiment 2 of this invention. It is a figure showing the structure of the period of the access control by the time division multiplex system by Embodiment 2 of this invention. It is a figure showing the structure of the slot information notification packet which concerns on Embodiment 2 of this invention. It is a figure showing the example of a structure of the data packet by Embodiment 2 of this invention. It is a block diagram which shows the structure of the communication control apparatus by Embodiment 2 of this invention. FIG. 5 is a flowchart for realizing a time division multiple access method of a communication control method according to Embodiment 2 of the present invention, and FIG. (A) is a flowchart showing an initial operation of a terminal immediately after power-on or reset, FIG. 5B is a flowchart showing the steady operation of the terminal other than the initial state. It is a flowchart which shows the empty slot detection operation | movement of the communication control method by Embodiment 2 of this invention. It is a figure showing the synchronization slot acquisition procedure by Embodiment 2 of this invention. It is a figure showing the slot information managed by the terminal information management part by Embodiment 2 of this invention, and Fig.9 (a) is a terminal information management part of each terminal when not all terminals are performing synchronous communication. FIG. 4B shows slot information managed by the terminal information management unit of the terminal F when the terminal F transmits the slot communication confirmation response packet, and FIG. F is slot information managed by the terminal information management unit of the terminals G and H when the slot notification operation is performed, and FIG. 4D is a terminal information management of the terminals G and H when the terminal E performs the slot notification operation. (E) shows the slot information managed by the terminal information management unit of the terminal H when the terminal G performs the slot notification operation. The figure showing the example of arrangement | positioning of the terminal which is a communication control apparatus by Embodiment 3 of this invention. It is a figure showing the synchronization slot acquisition procedure by Embodiment 3 of this invention. It is a figure which shows the data transmission sequence using RTS and CTS in the conventional radio | wireless communications system. It is a figure which shows the structure of the frame period which showed arrangement | positioning of the beacon slot in the conventional communication method, and the data slot which receives data. It is a figure which shows the position of the receiving slot of each terminal in the conventional communication method.

Explanation of symbols

101 Terminal A
102 Terminal B
103 Terminal C
104 Terminal D
105 Communication range of terminal A 106 Communication range of terminal B 107 Communication range of terminal C 108 Communication range of terminal D 201 Upper layer interface 202 Time synchronization unit 202a Time synchronization period timer 203 Lower layer interface 204 Transmission processing unit 205 Communication monitoring unit 206 Reception processing unit 301 Transmission destination terminal ID field 302 Transmission source terminal ID field 303 Time synchronization period field 304 Slot time field 305 Offset field 306 Slot number field 307 Reserved field 308 Status field 309 Packet type field 310 Synchronous communication request packet 320 Synchronous communication response Packet 601 terminal E
602 Terminal F
603 terminal G
604 terminal H
605 Communication range 800 Slot information notification packet 801 Packet type field 802 Transmission destination terminal ID field 803 Transmission source terminal ID field 804 Slot number notification field 805 Period field 806 Slot number field 807 Self terminal use slot field 808 Other terminal use slot field 900 Data Packet 901 Packet type field 902 Transmission destination terminal ID field 903 Transmission source terminal ID field 904 Slot number field 905 Payload 1001 Communication control device 1002 Interface 1003 Transmission / reception buffer 1004 Central control unit 1004a Communication control unit 1004b Free slot detection unit 1005 Packet generation unit 1006 Packet analysis unit 1007 Communication unit 1007a Send Parts 1007b receiver 1008 slot management unit 1008a slot information notification timer 1008b slot timer 1008c slot number management counter 1009 terminal information managing unit 1501 terminal I
1502 Terminal J
1503 Terminal K
1504 terminal L
1505 Communication range of terminal I 1506 Communication range of terminal J 1507 Communication range of terminal K 1508 Communication range of terminal L

Claims (29)

A communication network consisting of a plurality of terminals that does not have a control station or does not control access to the communication medium even if it exists, and communicates data by sharing the communication medium for peer communication between terminals. In a communication system,
Each terminal is
A time synchronization unit that performs processing for establishing time synchronization with a terminal that performs communication, using time synchronization information for establishing time synchronization regarding access timing to a communication medium;
A communication monitoring unit that monitors the time synchronization information transmitted and received in communication between other terminals,
The time synchronization information in the communication between other terminals obtained by the communication monitoring unit is transmitted to a terminal that is different from the other terminal and for which time synchronization is not established.
A communication system characterized by the above. The communication system according to claim 1,
Each terminal is
Based on the time synchronization information obtained by the communication monitoring unit, establish time synchronization of the terminal itself,
A communication system characterized by the above. The communication system according to claim 2,
Each terminal is
When the time synchronization information transmitted / received in communication between other terminals cannot be obtained, when the transmission is started, the time synchronization information is transmitted to request establishment of time synchronization.
A communication system characterized by the above. The communication system according to claim 3,
Each terminal is
When time synchronization is established with a terminal other than the transmission source terminal of the time synchronization information when the time synchronization information is received from another terminal, the time synchronization information corresponding to the time synchronization is set to the time synchronization information. Reply to the source terminal of the synchronization information,
A communication system characterized by the above. The communication system according to claim 4,
Each terminal is
As a response to the time synchronization establishment request, when receiving synchronization time information established with another terminal, according to the received synchronization time information, establish time synchronization of the own terminal,
A communication system characterized by the above. The communication system according to claim 1,
The time synchronization information is:
Including at least one of communication time information, communication cycle information, time information that a terminal can transmit per one cycle of time synchronization, and transmission start time information,
A communication system characterized by the above. The communication system according to claim 1,
Each terminal is
Set the time synchronization of the terminal based on the time when the terminal receives the time synchronization information,
A communication system characterized by the above. Communication control consisting of a plurality of terminals and performing data communication using a time division multiple access method between arbitrary terminals in a communication network that does not have a control station or does not control access to a communication medium even if it exists In the method
Each terminal is always in operation
Other terminal representing a slot used by a terminal different from the own terminal and a slot used by a terminal different from the own terminal, which represents a use status of a slot which is a communication time unit at an arbitrary timing. A slot notification step of notifying slot information composed of used slots to all other terminals existing in a position where the terminal can communicate directly;
A terminal information management step for managing the slot information of all the plurality of terminals including the notified slot information,
When performing data communication between the arbitrary terminals,
An empty slot detection step for detecting an unused slot using the slot information of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side;
A data communication step of performing data communication using the empty slot detected in the empty slot detection step,
A communication control method characterized by the above. The communication control method according to claim 8, wherein
The empty slot detection step includes:
Excluded from all slots the own terminal use slots of all the terminals that are managed in the terminal information management step in the terminal on the data communication start side and are directly communicable with the communication start side terminal, and remained Make the slot an empty slot,
A communication control method characterized by the above. The communication control method according to claim 9, wherein
The empty slot detection step includes:
When it is determined that there is a hidden terminal that cannot be directly communicated with the terminal on the data communication start side, use of the other terminal of the terminal on the data communication response side managed in the terminal information management step on the communication start side terminal A slot is excluded from the remaining slots, and the remaining slots are defined as empty slots.
A communication control method characterized by the above. The communication control method according to claim 8, wherein
The empty slot detection step includes:
The own terminal use slots and the other terminal use slots of all terminals that are managed in the terminal information management step in the data communication start terminal and that exist at positions where direct communication with the communication start terminal can be performed are all slots. And leave the remaining slots as empty slots.
A communication control method characterized by the above. The communication control method according to claim 8, wherein
The terminal information management step associates and manages the unique IDs of the plurality of terminals and the slot information notified by each terminal;
A communication control method characterized by the above. Communication control consisting of a plurality of terminals and performing data communication using a time division multiple access method between arbitrary terminals in a communication network that does not have a control station or does not control access to a communication medium even if it exists In the method
Each terminal is always in operation
Other than a slot that is not used by the own terminal and a slot that is not used by a terminal other than the own terminal, which represents the usage status of a slot that is a communication time unit at an arbitrary timing A slot notifying step for notifying all other terminals existing in a position where the terminal can communicate directly with slot information composed of terminal unused slots;
Each time the slot information is notified from the other terminal, a terminal information management step for managing the slot information of all the plurality of terminals including the notified slot information,
When performing data communication between the arbitrary terminals,
An empty slot detection step for detecting an unused slot using the slot information of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side;
A data communication step of performing data communication using the empty slot detected in the empty slot detection step,
A communication control method characterized by the above. The communication control method according to claim 13,
The empty slot detection step includes:
A common slot among the unused slots of the own terminal of all the terminals that are managed in the terminal information management step in the terminal on the data communication start side and that can be directly communicated with the terminal on the communication start side is vacant A slot,
A communication control method characterized by the above. The communication control method according to claim 14, wherein
The empty slot detection step includes:
When it is determined that there is a hidden terminal that cannot be directly communicated with the terminal on the data communication start side, use of the other terminal of the terminal on the data communication response side managed in the terminal information management step on the communication start side terminal Make the slot an empty slot,
A communication control method characterized by the above. The communication control method according to claim 13,
The empty slot detection step includes:
Of the own terminal use slot and the other terminal use slot of all terminals that are managed in the terminal information management step in the data communication start side terminal and are located at a position where direct communication with the communication start side terminal is possible Let the common slot be an empty slot,
A communication control method characterized by the above. The communication control method according to claim 13,
The terminal information management step associates and manages the unique IDs of the plurality of terminals and the slot information notified by each terminal;
A communication control method characterized by the above. It consists of a plurality of terminals, and there is no control station, or even if it exists, it does not control access to the communication medium. In the communication control device of the terminal,
A slot used by a terminal other than the own terminal and a slot used by the terminal representing the slot used by the own terminal, which indicates the usage status of a slot as a communication time unit at an arbitrary timing during normal operation When notifying all other terminals present in a position where the terminal can communicate directly, and performing data communication between the arbitrary terminals, the slot information configured by other terminal use slots representing A communication control unit for controlling
Each time the slot information is notified from the other terminal, a terminal information management unit that manages the slot information of all the plurality of terminals including the notified slot information;
When performing data communication between the arbitrary terminals, an unused slot is detected using the slot information of all the plurality of terminals managed by the terminal information management unit of the terminal on the data communication start side An empty slot detector to
A communication control device. The communication control device according to claim 18, wherein
The empty slot detector
Exclude the slot used by all terminals of all terminals that are managed by the terminal information management unit of the terminal on the data communication start side and in a position capable of directly communicating with the terminal on the communication start side from all slots, and remain Set the slot as an empty slot,
A communication control device. The communication control device according to claim 19,
The empty slot detector
When it is determined that there is a hidden terminal that the terminal on the data communication start side cannot directly communicate with, the other terminal use of the terminal on the data communication response side managed by the terminal information management unit of the communication start side terminal A slot is excluded from the remaining slots, and the remaining slots are defined as empty slots.
A communication control device. The communication control device according to claim 18, wherein
The empty slot detector
The own terminal use slots and the other terminal use slots of all the terminals that are managed by the terminal information management unit of the data communication start side terminal and are directly communicable with the communication start side terminal are all slots And leave the remaining slots as empty slots.
A communication control device. The communication control device according to claim 18, wherein
The terminal information management unit manages the unique ID of the terminal in association with the slot information notified by the terminal,
A communication control device. It consists of a plurality of terminals, and there is no control station, or even if it exists, it does not control access to the communication medium. In the communication control device of the terminal,
During normal operation, it shows the usage status of slots, which are communication time units, at any timing, and is not used by its own terminal unused slot that represents a slot that is not used by its own terminal, or by a terminal other than the own terminal. Notifying all other terminals that are located in a position where the terminal can communicate directly with the slot information composed of slots not used by other terminals representing the slot, and when performing data communication between the arbitrary terminals, A communication control unit for controlling data communication;
Each time the slot information is notified from the other terminal, a terminal information management unit that manages the slot information of all the plurality of terminals including the notified slot information;
When performing data communication between the arbitrary terminals, an unused slot is detected using the slot information of all the plurality of terminals managed by the terminal information management unit of the terminal on the data communication start side An empty slot detector to
A communication control device. The communication control device according to claim 23,
The empty slot detector
A common slot among the unused slots of the own terminal of all the terminals that are managed by the terminal information management unit of the terminal on the data communication start side and that can be directly communicated with the transmitting terminal is defined as an empty slot. To
A communication control device. The communication control device according to claim 24,
The empty slot detector
When it is determined that there is a hidden terminal that the terminal on the data communication start side cannot directly communicate with, the other terminal use of the terminal on the data communication response side managed by the terminal information management unit of the communication start side terminal Make the slot an empty slot,
A communication control device. The communication control device according to claim 23,
The empty slot detector
Of the own terminal use slot and the other terminal use slot of all the terminals that are managed by the terminal information management unit of the data communication start side terminal and are directly communicable with the communication start side terminal Let the common slot be an empty slot,
A communication control device. The communication control device according to claim 23,
The terminal information management unit manages the unique ID of the terminal in association with the slot information notified by the terminal;
A communication control device. Communication that consists of multiple terminals and that performs data communication processing using a time division multiple access method between any terminals in a communication network that does not have a control station or does not control access to the communication medium even if it exists A communication control program included in each terminal for causing a computer to execute control processing,
During normal operation,
Other terminal representing a slot used by a terminal different from the own terminal and a slot used by a terminal different from the own terminal, which represents a use status of a slot which is a communication time unit at an arbitrary timing. A slot notification step of notifying slot information composed of used slots to all other terminals existing in a position where the terminal can communicate directly;
Each time the slot information is notified from the other terminal, a terminal information management step for managing the slot information of all the plurality of terminals including the notified slot information,
When performing data communication between the arbitrary terminals,
An empty slot detection step for detecting an unused slot using the slot information of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side;
A data communication step of performing data communication using the empty slot detected in the empty slot detection step,
A communication control program characterized by the above. Communication that consists of multiple terminals and that performs data communication processing using a time division multiple access method between any terminals in a communication network that does not have a control station or does not control access to the communication medium even if it exists A communication control program included in each terminal for causing a computer to execute control processing,
During normal operation,
Other than a slot that is not used by the own terminal and a slot that is not used by a terminal other than the own terminal, which represents the usage status of a slot that is a communication time unit at an arbitrary timing A slot notifying step for notifying all other terminals existing in a position where the terminal can communicate directly with slot information composed of terminal unused slots;
Each time the slot information is notified from the other terminal, a terminal information management step for managing the slot information of all the plurality of terminals including the notified slot information,
When performing data communication between the arbitrary terminals,
An empty slot detection step for detecting an unused slot using the slot information of all the plurality of terminals managed in the terminal information management step in the terminal on the data communication start side;
A data communication step of performing data communication using the empty slot detected in the empty slot detection step,
A communication control program characterized by the above.

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