JP4627231B2 - One-to-many communication method and apparatus - Google Patents

Description

  The present invention relates to a one-to-many communication method and apparatus, and more particularly, to a one-to-many communication method and apparatus that realizes a one-to-many communication broadcast or multicast using unicast communication.

  Broadcast and multicast are known as transmission modes in which messages and data are received by a plurality of nodes on a network in a single transmission. In order to realize one-to-many communication such as broadcast on the network, it is necessary that a broadcast or multicast protocol is previously installed in each node.

On the other hand, Bluetooth (registered trademark) is known as a communication standard for wirelessly connecting mobile devices such as mobile phones and PDAs and other various electronic devices. Bluetooth is a method of short-range wireless data communication technology, and performs wireless transmission and reception by spread spectrum using the ISM band (2.4 GHz charged wave). In Bluetooth, specifications for software or devices to use wireless communication are defined as profiles (protocol stacks). Patent Document 1 discloses a communication system using a Bluetooth device.
JP 2002-77185 A

  A number of profiles are prepared for Bluetooth, and SPP (Serial Port Profile) is prepared as a profile for realizing wireless communication. However, since SPP only supports unicast and not broadcast or multicast, Bluetooth cannot implement one-to-many communication such as broadcast or multicast. Such a technical problem is not limited to Bluetooth, but is a technical problem common to all networks that support only one-to-one communication as a transmission form and do not support one-to-many communication.

  Note that even with Bluetooth, piconet allows one-to-many communication from a master to multiple slaves, but piconet requires negotiation to determine master / slave attributes and limits the number of connectable slaves. Generality is not high due to restrictions such as

  An object of the present invention is to solve the above-described problems of the prior art and perform one-to-many broadcast communication and multicast communication in a pseudo manner by using unicast communication in a communication environment that supports only unicast communication. It is to provide a method and apparatus.

In order to achieve the above-described object, the present invention provides the following procedure in a one-to-many communication method and apparatus for realizing one-to-many broadcast communication or multicast communication in a unicast communication environment. Features.
(1) A procedure in which each wireless node on the network identifies the address of each adjacent node adjacent to the own node, a procedure in which each wireless node sequentially transmits data to each adjacent node in a predetermined order by unicast, Each wireless node receiving the data sequentially transmits the data in a predetermined order to each adjacent node by unicast.
(2) Each wireless node stores the address of the adjacent node that transmitted the data to its own node, and then receives the same data from another adjacent node, and then transmits the data to the adjacent node that transmitted the data to the own node. Is not transmitted.
(3) Each wireless node randomly determines the order in which data is transmitted to each adjacent node by unicast.
(4) Each wireless node has a plurality of transmission rules that define the order in which data is transmitted to each adjacent node by unicast, a procedure for determining the attributes of received data, and a transmission rule according to the determination result And a procedure of sequentially transmitting received data to each adjacent node in an order according to the selected transmission rule.
(5) The plurality of rules include a first rule for transmitting data in descending order of destination addresses and a second rule for transmitting data in ascending order of destination addresses.
(6) Each wireless node includes a procedure for registering an address of an adjacent node in transmission data and a procedure for prohibiting transmission to an adjacent node whose address is registered in reception data.

According to the present invention, the following effects are achieved.
According to the above feature (1), broadcast communication and multicast communication can be realized in a pseudo manner even in a unicast communication environment.
According to the above feature (2), it is possible to prevent redundant data transmission to an upper adjacent node that does not require data transfer.
According to the above feature (3), since the destination address of data in each wireless node is selected at random, it is possible to prevent data transfer from concentrating on a specific wireless node.
According to the above features (4) and (5), the data destination address is selected in ascending or descending order according to the attribute of the data in each wireless node, so that data transfer is concentrated on a specific wireless node. Can be prevented.
According to the above feature (6), it is possible to prevent redundant data transfer to an adjacent node to which data has already been transferred or is scheduled to be transferred by an upper adjacent node.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a wireless node to which the present invention is applied, and illustrations of components unnecessary for the description of the present invention are omitted. Here, a case where broadcast communication is realized in a pseudo manner in a unicast communication environment will be described as an example.

  The wireless node 1 includes a Bluetooth module (hereinafter referred to as “BM”) 11 that performs short-range wireless communication compliant with the Bluetooth communication standard via the antenna 10, and a main control unit 12 that controls the entire wireless node 1. A ROM 13 storing a plurality of profiles including at least SPP, and rules for transmitting data to a plurality of adjacent links in order, a RAM 14 providing a work area to the main control unit 12, and various data Is stored in a nonvolatile manner, and an I / O interface 16 that accepts an operation of the operation unit 15 is provided. The BM 11 includes an RF chip 11a for frequency hopping spread spectrum communication supporting the 2.4 GHz band, a BB chip 11b as a link controller for controlling transmission / reception of baseband (BB) signals, and the like. .

  FIG. 2 is a functional block diagram of the wireless node 1 and shows the processing executed by the main control unit 12 and the BM 11 according to programs or data stored in the ROM 13 or the SRAM 17 by function.

  The adjacent node identification unit 21 recognizes the address of each adjacent node located within the communication effective range of the own node and accumulates it in the adjacent node list 27. The data attribute identification unit 22 identifies the number of hops reaching the node registered in the data as the attribute of the data to be transmitted. In the transmission rule storage unit 23, a plurality of rules relating to the transmission order when the own node transmits data to each adjacent node in order by unicast are registered. In the present embodiment, a first rule that is transmitted in order from an adjacent node with a small address, that is, an ascending order, and a second rule that is transmitted in order from an adjacent node with a large address, that is, in descending order, are registered.

  The transmission rule selection unit 24 selects the first or second rule based on the identification result by the data attribute identification unit 22. In the transfer prohibition list 26, the addresses of adjacent nodes for which data transfer is prohibited are registered. The destination selection unit 25 sequentially selects destination addresses from the adjacent node list 27 according to the selected transmission rule. The BM 11 transmits data to the selected destination according to SPP by unicast.

  Next, functions of the data attribute identification unit 22, the transmission rule storage unit 23, and the transmission rule selection unit 28 will be described.

  In this embodiment, as will be described in detail below, unicast communication is realized in a pseudo manner by sequentially repeating unicast communication with each adjacent node. However, each wireless node includes a plurality of adjacent nodes. If destinations are selected in order from among them, if the selection is made based on the same rule, data transmission may be concentrated on some adjacent nodes.

  FIG. 10 is a diagram schematically showing how data transfer destinations are concentrated on some adjacent nodes, and FIG. 11 is a sequence diagram thereof. In FIG. 10, each circle indicates a wireless node, and a number in the circle indicates an address assigned to each wireless node.

  Here, consider the case where the wireless node with address “3” transmits data to all wireless nodes on the network by broadcast, and each wireless node is prohibited from transferring data to the adjacent node that transmitted the data to its own node. It shall be.

  If the rule regarding the transmission order in each wireless node is “ascending order of addresses”, the wireless node at address “3” is included in the adjacent nodes in the first transmission cycle (turn) as shown in FIG. The address is transmitted to the wireless node having the minimum value “1”. In the next second period, as shown in FIG. 4B, the wireless node with address “3” transmits to the wireless node with address “2”, and the wireless node with address “1” is also among the adjacent nodes. The address is transmitted to the wireless node having the minimum value “2”.

  Similarly, in the next third period, as shown in FIG. 5C, all the wireless nodes with addresses “3”, “1”, and “2” transmit to the wireless node with address “4”. The data transfer is concentrated on the wireless node having the address “4”. In the next fourth period, as shown in FIG. 4D, all the wireless nodes with addresses “1”, “2”, “3”, and “4” transmit to the wireless node with address “5”. Therefore, the data transfer is concentrated on the wireless node having the address “5”.

  In order to cope with such a technical problem, in this embodiment, a data attribute identification unit 22, a transmission rule storage unit 23, and a transmission rule selection unit 28 are provided, and the transmission order of data is determined according to different rules in each wireless node. I am doing so.

  Next, the operation of the present embodiment will be described along the flowchart of FIG. If it is detected in step S1 that data having a broadcast address as a destination is generated by the own node, the process proceeds to step S4, and otherwise, the process proceeds to step S2. In step S2, it is determined whether or not data having a broadcast address is received. If reception is detected, the process proceeds to step S3. In step S3, the address of the adjacent node that transferred the data to the own node is registered in the transfer prohibition list 26 together with an identifier that can uniquely identify the data. In step S4, the number of hops stored in the data is newly registered or updated (incremented).

  In step S5, the data attribute identification unit 22 identifies the number of newly registered or updated hops as attribute information, and the transmission rule selection unit 24 performs even / odd determination. If there is, the process proceeds to step S6 and the first rule is selected. On the other hand, if the identification result of the number of hops is an even number, the process proceeds to step S7 and the second rule is selected. In the present embodiment, a rule for transmitting in order (ascending order) from an adjacent node having a small address as the first rule is a rule for transmitting in order (descending order) from an adjacent node having a large address as the second rule. 23.

  In step S8, only one destination address is selected from the adjacent node list 27 by the destination selection unit 25 in accordance with the selected transmission rule. In step S9, it is determined whether or not the selected destination address is registered in the transfer prohibition list 26. If it is not registered in the transfer prohibition list 26, the process proceeds to step S10, and a unique communication channel is secured between the destination and the destination. In step S11, data is transmitted by unicast using the reserved communication channel.

  In step S12, it is determined whether or not the data transfer to all the adjacent nodes (excluding the adjacent nodes registered in the transfer prohibition list) is completed. The next destination address is selected from the adjacent node list 27 in accordance with the transmission rule. The above process is repeated until data transfer by unicast to all adjacent links (same as above) registered in the adjacent node list 27 is completed.

  FIG. 8 is a diagram schematically showing the effect of this embodiment, and FIG. 9 is a sequence diagram thereof. In FIG. 8, each circle indicates a wireless node, and a number in the circle indicates an address assigned to each wireless node. Here, a case is considered in which the wireless node with the address “3” transmits data to all wireless nodes on the network by broadcast.

  In the wireless node with the address “3”, the hop count of the transmission data is the initial value “1”, and “ascending order” is selected as the transmission rule. Therefore, in the first transmission cycle, as shown in FIG. 8A, data is transmitted from the wireless node at address “3” to the wireless node at address “1” by unicast. In the wireless node with the address “1”, the number of hops of data to be transmitted is updated to “2”, so “descending order” is selected as the transmission rule. Accordingly, in the next second period, as shown in FIG. 5B, the wireless node with address “3” transmits to the wireless node with address “2”, and the wireless node with address “1” transmits the address “ 5 ”is transmitted to the wireless node.

  In the wireless nodes of the addresses “2” and “5”, the hop count of the transmission data is updated to “3”, so “ascending order” is selected as the transmission rule. Therefore, in the next third period, as shown in FIG. 5C, the wireless node with address “3” transmits to the wireless node with address “4”, and the wireless node with address “1” transmits the address “ The wireless node at address “2” is transmitted to the wireless node at address “5”, and the wireless node at address “5” is transmitted to the wireless node at address “3”.

  Thus, according to the present embodiment, broadcast communication can be realized in a pseudo manner even in a unicast communication environment. Further, in this embodiment, the destination address of data in each wireless node is selected in ascending or descending order according to the attribute of the data, so that data transfer can be prevented from concentrating on a specific wireless node.

  In the first embodiment described above, one transmission rule is selected for each radio node according to the data attribute from the two transmission rules. However, three or more transmission rules are prepared, Any one transmission rule may be selected according to the attribute.

  FIG. 4 is a functional block diagram of a second embodiment of a wireless node having a one-to-many communication function according to the present invention. The same reference numerals as those described above represent the same or equivalent parts. In this embodiment, a random number generation unit 28 is provided instead of the data attribute identification unit 22, the transmission rule storage unit 23, and the transmission rule selection unit 28, and the destination selection unit 25 randomly selects a destination address from the adjacent node list 27. There is a feature in the point made to do.

  FIG. 5 is a flowchart showing the operation of the present embodiment, in which the same reference numerals are written in the procedures in which the same or equivalent processes are executed.

  In step S21, when it is detected that data having a broadcast address as a destination is generated in the own node, the process proceeds to step S24, and otherwise, the process proceeds to step S22. In step S22, it is determined whether or not data having a broadcast address is received. If reception is detected, the process proceeds to step S23. In step S23, the address of the adjacent node that transferred the data to its own node is registered in the transfer prohibition list 26. In step S24, the number of hops stored in the data is newly registered or updated (incremented).

  In step S25, the destination selection unit 25 selects only one destination address from the adjacent node list 27 based on the random number generated by the random number generation unit 28. In step S26, it is determined whether or not the selected destination address is registered in the transfer prohibition list 26. If it is not registered in the transfer prohibition list 26, the process proceeds to step S27, and a unique communication channel is secured with the destination. In step S28, data is transmitted by unicast using the reserved communication channel.

  In step S29, it is determined whether or not the data transfer to all adjacent nodes (excluding the adjacent nodes registered in the transfer prohibition list) is completed. If not completed, the process returns to step S25, and the adjacent node list 27, the next destination address is selected at random. The above process is repeated until data transfer by unicast to all adjacent links (same as above) registered in the adjacent node list 27 is completed.

  According to this embodiment, since the destination address is randomly selected in each wireless node, it is possible to prevent data transfer from being concentrated on a specific wireless node.

  Tables 1 to 4 show a first arrangement pattern (Table 1 and Table 2) in which 10 terminals are randomly arranged in a 400 m × 400 m square field, and 120 terminals in a 1000 m × 250 m rectangular field. It is the result of measuring the number of transmission turns until the completion of flooding for each transmission rule with respect to the second arrangement pattern (Tables 3 and 4) randomly arranged. Here, when the transmission rule of the first embodiment (“ascending order” or “descending order” is selected according to the even number of hops for each terminal) is adopted, and the transmission rule of the second embodiment (for each terminal) The transmission order is determined at random) and the case where the transmission order is fixed in ascending order of the number of hops in all terminals, two patterns of terminal arrangements in each field were prepared and measured. . The radio wave propagation distance of each terminal is 250 meters.

  It can be seen that under any condition, by adopting the transmission rules of the first and second embodiments, the flooding can be completed with a smaller number of turns than when the transmission order is fixed in all terminals.

  FIG. 6 is a functional block diagram of a third embodiment of a wireless node having a one-to-many communication function according to the present invention. The same reference numerals as those described above represent the same or equivalent parts. In the present embodiment, in addition to the configuration of the first embodiment, the adjacent node list registration unit 30 that registers the adjacent node list of the own node in the transmission data and the adjacent node list registered in the received data are extracted. And an adjacent node list extraction unit 29 registered in the transfer prohibition list 26.

  FIG. 7 is a flowchart showing the operation of the present embodiment, and the same reference numerals are written together in the procedures in which the same or equivalent processes are executed.

  In step S41, when it is detected that the data having the destination broadcast address is generated in the own node, the process proceeds to step S45, and the address of the adjacent node registered in the adjacent node list 27 is stored in the adjacent node list registration unit. 30, the data is registered in the data, and then the process proceeds to step S46. On the other hand, if it is detected in step S42 that the data having the destination broadcast address is received, the process proceeds to step S43, and the adjacent node address registered in the data is extracted by the adjacent node list extraction unit 29. . In step S44, the address of the adjacent node that transferred the data to its own node and the adjacent node address of the upper node extracted from the received data are registered in the transfer prohibition list 26. In step S46, the number of hops stored in the data is newly registered or updated (incremented).

  In step S47, the data attribute identification unit 22 identifies the number of newly registered or updated hops as attribute information, and the transmission rule selection unit 24 performs even / odd determination. If the identification result of the number of hops is an odd number, the process proceeds to step S48 and the first rule is selected. On the other hand, if the identification result of the number of hops is an even number, the process proceeds to step S49 and the second rule is selected.

  In step S50, according to the selected transmission rule, only one destination address is selected from the adjacent node list 27 by the destination selection unit 25. In step S51, it is determined whether or not the selected destination address is registered in the transfer prohibition list 26. If it is not registered in the transfer prohibition list 26, the process proceeds to step S52, and a unique communication channel is secured with the destination. In step S53, data is transmitted by unicast using the reserved communication channel.

  In step S54, it is determined whether or not the data transfer to all adjacent nodes (excluding the adjacent nodes registered in the transfer prohibition list) is completed. If not completed, the process returns to step S50 and the selection is made. The next destination address is selected from the adjacent node list 27 in accordance with the transmission rule. The above process is repeated until data transfer by unicast to all adjacent links (same as above) registered in the adjacent node list 27 is completed.

  According to the present embodiment, each wireless node that transfers data to an adjacent node registers and transmits the adjacent node list of its own node in the data, and each adjacent node that receives this transmits the adjacent node registered in the received data. Since the node list is registered in the transfer prohibition list, redundant data transfer to an adjacent node to which data has already been transferred or is scheduled to be transferred can be prevented.

  In each of the above-described embodiments, the present invention has been described using pseudo broadcast communication as an example. However, the present invention is not limited to this, and can be similarly applied to pseudo multicast communication.

It is a block diagram of the radio | wireless node to which this invention is applied. It is a functional block diagram of 1st Embodiment of the radio | wireless node which concerns on this invention. It is the flowchart which showed operation | movement of 1st Embodiment. It is a functional block diagram of 2nd Embodiment of the radio | wireless node which concerns on this invention. It is the flowchart which showed the operation | movement of 2nd Embodiment. It is a functional block diagram of 3rd Embodiment of the radio | wireless node which concerns on this invention. It is the flowchart which showed the operation | movement of 3rd Embodiment. It is the figure which showed typically the effect of 1st Embodiment of this invention. It is the sequence diagram which showed the effect of 1st Embodiment of this invention. It is the figure which showed typically the technical subject peculiar to the pseudo broadcast communication using unicast communication. It is the sequence diagram which showed the technical subject peculiar to the pseudo broadcast communication using unicast communication.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Bluetooth module, 21 ... Adjacent node identification part, 22 ... Data attribute identification part, 23 ... Transmission rule memory | storage part, 24 ... Transmission rule selection part, 25 ... Destination selection part, 26 ... Transfer prohibition list, 27 ... Adjacent node list

Claims (6)

In the one-to-many communication method for realizing one-to-many broadcast communication or multicast communication in a unicast communication environment,
Each wireless node on the network,
A procedure for identifying the address of each adjacent node connected to the own node via a radio link ;
A procedure for receiving data transmitted by unicast from an adjacent node;
A procedure for determining a value according to the number of hops until the received data reaches the node;
A procedure for selecting one of a first rule for transmitting data in ascending order of destination addresses and a second rule for transmitting data in descending order based on the determination result;
A one-to-many communication method comprising: sequentially transmitting the received data to each adjacent node by unicast in an order according to the selected transmission rule .   Each wireless node stores the address of an adjacent node that has transmitted data to its own node, and thereafter, when the same data is received from another adjacent node, the data is transmitted to the adjacent node that has transmitted data to the own node. The one-to-many communication method according to claim 1, wherein the one-to-many communication method is not performed. Each wireless node is
Registering the address of the adjacent node in the transmission data;
3. The one-to-many communication method according to claim 1, further comprising a procedure for prohibiting transmission to an adjacent node whose address is registered in received data. In a communication device that realizes one-to-many broadcast communication or multicast communication in a unicast communication environment,
Each wireless node
Means for identifying an address of each adjacent node connected to the own node through a radio link;
Means for storing a first rule for transmitting data in ascending order of destination addresses and a second rule for transmitting in descending order as transmission rules for determining the order in which data is transmitted in unicast to each adjacent node;
Means for receiving data transmitted by unicast from an adjacent node;
Means for determining a value according to the number of hops until the received data reaches its own node;
Means for selecting one of the first and second rules based on the determination result;
Means for sequentially transmitting the received data in a sequence according to the selected transmission rule to each adjacent node by unicast. Comprising means for storing the address of an adjacent node that has transmitted data to the own node;
5. The one-to-many communication apparatus according to claim 4 , wherein when the same data is received from another adjacent node, the data is not transmitted to the adjacent node that has transmitted the data to the own node. Means for registering the address of the adjacent node in the transmission data;
6. The one-to-many communication apparatus according to claim 4 , further comprising means for prohibiting transmission to an adjacent node whose address is registered in received data.

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