JP2009188924A - Radio communication apparatus, method and program, and radio network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make power consumption of a radio terminal reduced by reducing the starting time of a radio, while considering to make small the communication delay between radio terminals configuring a radio network. <P>SOLUTION: In a radio communication apparatus which a plurality of radio terminals configuring the radio network equips respectively, the radio communication apparatus includes a receiving slot information communication means which transmits receiving slot information which shows the receiving period of a self terminal to surrounding radio terminals, a destination terminal determination means which determines a destination terminal of the self terminal among the surrounding radio terminals based on the receiving slot information from the surrounding radio terminals, a receiving slot determination means which determines the receiving slot of the self terminal before the receiving slot of the destination terminal based on the receiving slot information of the destination terminal determined by the destination terminal determination means, and a transfer processing means which carries out the transfer processing of a data signal in the receiving slot of the self terminal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus, method and program, and a wireless network. For example, in a multi-hop wireless network used for a sensor network, a wireless that performs power supply control to reduce power consumption of a wireless terminal that performs relay processing. The present invention can be applied to communication apparatuses, methods and programs, and wireless networks.

  2. Description of the Related Art Conventionally, various systems have been developed that realize communication between terminals that are not directly connected by configuring a network with a plurality of terminals and repeating packet transmission / reception between adjacent terminals.

  As a technique for realizing such communication, for example, a method of allowing a receiving terminal that receives a packet to always turn on the receiver and perform communication at an arbitrary time, or synchronization between transmitting and receiving terminals. There is a method in which transmission is permitted only at a specific time designated by the receiving terminal (so-called TDMA method). These systems assume that one of the terminals that performs transmission / reception is a fixed base station and that power is supplied.

  For example, in a sensor network or an ad hoc network, a terminal that performs reception processing also functions as a terminal that transmits packets to other terminals, and both terminals that perform transmission and reception are generally in a state where there is no power supply. is there.

  In such a state, synchronization between transmitter / receiver terminals is performed, the receiver is turned on for communication only during a part of the time, and communication is performed at other times. Various methods have been developed for this as well.

  However, in order to reduce the power consumption of the wireless terminal, it is necessary to increase the rate of time for turning off the power of the transceiver. Since the time required for a certain amount of communication is constant as long as the communication method is not changed, in order to increase the ratio of the time to turn off the power of the transceiver, a long pause time is taken. Accordingly, the time during which communication is possible within a certain period of time decreases, and the time required for communication increases. That is, the problem that communication delay increases occurs. In multi-hop communication in which wireless communication is repeated a plurality of times, the delay time increases in proportion to the number of relays, which is a more serious problem.

  In the existing method that enables communication while taking into account the downtime, the transmission time is specified for each terminal so that a plurality of terminals do not transmit packets to the same terminal at the same time. . However, in such a system, a terminal that needs to receive packets from a plurality of terminals increases the time to turn on the radio.

  In order to solve this problem, for example, Patent Document 1 describes a technique for adjusting the transmission timings of all terminals from a terminal where a packet is generated to the final destination in advance in order to reduce delay due to relaying. Yes.

JP 2007-43435 A

  By the way, for example, in a wireless network used for a sensor network or the like, there are many situations where the amount of communication is small, and most of the time when the wireless device is turned on only waits for reception. Therefore, in such a communication situation, there is a problem that the existing method for managing the transmission time has a lot of power consumption. In addition, communication is rarely performed in both directions, and unilateral communication to a specific terminal (a special terminal having a function of connecting to an external network or a management function of the entire sensor network) is often the main subject.

  Therefore, a wireless communication apparatus, method, and program capable of reducing the start-up time of the wireless device and reducing the power consumption of the wireless terminal while considering reducing the communication delay between the wireless terminals constituting the wireless network There is also a need for a wireless network.

  In order to solve this problem, a wireless communication device according to a first aspect of the present invention is a wireless communication device provided in each of a plurality of wireless terminals constituting a wireless network. (2) a transmission destination terminal that determines a transmission destination terminal of its own terminal from the peripheral wireless terminals based on reception slot information from the peripheral wireless terminals (3) a receiving slot determining means for determining the receiving slot of the terminal before the receiving slot of the destination terminal based on the receiving slot information of the destination terminal determined by the destination terminal determining means; (4) It is characterized by comprising transfer processing means for performing a data signal transfer process in the reception slot of the terminal itself.

  According to a second aspect of the present invention, there is provided a wireless communication method of a wireless communication device provided in each of a plurality of wireless terminals constituting a wireless network, wherein the wireless communication device includes a reception slot information communication unit, a transmission destination terminal determination unit, (1) a reception slot information communication step in which the reception slot information communication means transmits / receives reception slot information indicating a reception period of the own terminal to / from neighboring wireless terminals; 2) a transmission destination terminal determination step in which the transmission destination terminal determination means determines a transmission destination terminal of the own terminal from the peripheral wireless terminals based on reception slot information from the peripheral wireless terminals; and (3) a reception slot. Based on the reception slot information of the transmission destination terminal determined by the transmission destination terminal determination unit, the determination unit sets the reception slot of the own terminal before the reception slot of the transmission destination terminal. A reception slot decision step constant to, (4) transfer processing means, and having a transfer processing step for performing transfer processing of the data signal at the receiving slot of the terminal.

  According to a third aspect of the present invention, there is provided a wireless communication program of a wireless communication device provided in each of a plurality of wireless terminals constituting a wireless network. (2) a transmission destination for determining a transmission destination terminal of the own terminal from the peripheral wireless terminals based on the reception slot information from the peripheral wireless terminals; (3) receiving slot determining means for determining the receiving slot of the own terminal before the receiving slot of the destination terminal based on the receiving slot information of the destination terminal determined by the destination terminal determining means; 4) It functions as a transfer processing means for performing a data signal transfer process in the reception slot of its own terminal.

  A wireless network according to a fourth aspect of the present invention includes a wireless communication apparatus according to the first aspect of the present invention in which each wireless terminal exchanges information between wireless terminals in a wireless network configured with a plurality of wireless terminals. It is characterized by being.

  According to the present invention, by creating a plurality of transfer paths in a wireless network, avoiding interference / collision of wireless signals, equalizing power consumption between terminals or reducing total power consumption, failure of terminals, or between terminals It is possible to avoid communication interruption due to disconnection of the wireless link.

(A) First Embodiment A wireless communication device, method and program, and a wireless network according to a first embodiment of the present invention will be described below with reference to the drawings.

  In the first embodiment, an embodiment in which the present invention is applied to a wireless terminal constituting a wireless network adopting a wireless multi-hop method will be described as an example.

  In the first embodiment, the problem of increasing the operating time of a radio device is solved by managing the reception time of each radio terminal instead of managing the transmission time. Regarding reduction of communication delay, an increase in communication delay is suppressed not by the transmission timing of each wireless terminal but by the reception timing of each wireless terminal after considering the communication path in the wireless network.

(A-1) Configuration of First Embodiment FIG. 1 is a configuration diagram illustrating a configuration example of a wireless multi-hop network according to the first embodiment.

  In FIG. 1, a wireless multi-hop network 10 according to the first embodiment includes a plurality of wireless terminals 101 to 111. The wireless terminal 101 is a wireless terminal (hereinafter also referred to as a coordinator) having a management function for managing the entire network.

  In FIG. 1A, a straight line connecting two wireless terminals indicates that the two wireless terminals can directly communicate with each other. The network configuration shown in FIG. 1B corresponds to that of FIG. 1A, and the numbers in the circles are time slot numbers, which correspond to the time slot numbers of FIG. 2 described later.

  Here, FIG. 2 is an explanatory diagram for explaining the time slots of the wireless terminals 101 to 111. In FIG. 2, only 100 time slots of a predetermined time are arranged in time series, and time slot numbers 1 to 100 for identifying the time slots are assigned to the respective time slots. Further, for convenience of explanation, a case where the time slot numbers are increased and the time is arranged later is shown. Of course, the time slot time, the number of time slots, the way of assigning the time slot number, etc. are not particularly limited.

  FIG. 3 is an internal configuration diagram illustrating an internal configuration of the wireless terminals 101 to 111 according to the first embodiment. In FIG. 3, the wireless terminals 101 to 111 according to the first embodiment include an antenna unit 301, a reception circuit unit 302, a transmission circuit unit 303, a reception data processing unit 304, a transmission data generation unit 305, and a state management unit 306. Configured.

  The antenna unit 301 is an antenna unit for transmitting or receiving a radio signal. When receiving the radio signal, the antenna unit 301 provides the reception signal to the reception circuit unit 302 and transmits the transmission signal from the transmission circuit unit 303 as a radio signal. is there. Note that although a case where a transmission / reception antenna unit is applied is described as the antenna unit 301, a transmission antenna unit and a reception antenna unit may be applied as the antenna unit 301, respectively.

  The reception circuit unit 302 converts the received signal from the antenna unit 301 into a digital signal by demodulation processing and gives the digital data to the received data processing unit 304 as received data.

  The reception data processing unit 304 performs predetermined processing on the reception data addressed to the terminal received from the reception circuit unit 302 and supplies necessary data to the state management unit 306. When the reception data processing unit 304 receives a data signal addressed to a terminal other than the terminal itself, the reception data processing unit 304 determines a transfer destination based on information obtained from the state management unit 306, and transmits transmission data as a data signal addressed to the transfer destination. This is given to the generation unit 305.

  The transmission circuit unit 303 receives the transmission data generated by the transmission data generation unit 305 from the transmission data generation unit 305, modulates the transmission data, and gives it to the antenna unit 301.

  The transmission data generation unit 305 generates transmission data addressed to the transfer destination using the peripheral terminal information obtained from the state management unit 306 and supplies the transmission data to the transmission circuit unit 303. The transmission data generation unit 305 uses the peripheral terminal information of the state management unit 306 to transfer data signals addressed to other terminals.

  The state management unit 306 collects information from surrounding wireless terminals via the reception data processing unit 304, determines a transmission destination terminal based on this information, and determines a reception period of the terminal itself. is there. As described above, the state management unit 306 determines the reception period of its own terminal, thereby controlling the power of the wireless device to be ON only during the reception period, and controlling the power of the wireless device to be OFF during other periods. , Power consumption can be reduced. For such control, for example, a known method such as a power management unit (not shown) can be used.

  FIG. 4 is a functional block diagram illustrating main internal functions of the state management unit 306. As illustrated in FIG. 4, the state management unit 306 includes at least a peripheral terminal information management unit 31, a reception slot notification reception period adjustment unit 32, a transmission destination terminal determination unit 33, and a reception slot determination unit 34.

  The peripheral terminal information management unit 31 manages peripheral wireless terminal information based on signals collected from the peripheral terminals. The signal from the peripheral terminal includes at least information indicating the reception slot of the peripheral terminal itself (for example, a time slot number assigned to the local terminal), and the notification indicating the reception slot is referred to as reception slot notification. . The communication signal may include terminal identification information for identifying the peripheral terminal itself, transmission timing, and the like.

  The reception slot notification reception period adjustment unit 32 determines the time for receiving the reception slot notification transmitted by the peripheral terminal.

  As a method for determining the reception period of the reception slot notification, any of the following methods can be applied.

  (1-1) A method of receiving a reception slot notification for a predetermined time after the own terminal is activated. In this case, the reception slot notification reception period adjustment unit 32 can be realized by not accepting reception of the reception slot notification when a predetermined time has elapsed since the start of the own terminal. Thereby, when all the wireless terminals are time-synchronized, the reception period of the reception slot notification can be matched between all the wireless terminals.

  (1-2) A method of receiving a reception slot notification for a predetermined time after receiving a reception slot notification for the first time. In this case, the reception slot notification reception period adjustment unit 32 receives the reception slot notification from the peripheral terminal until a predetermined time elapses after the reception slot notification is first received from the peripheral terminal after the own terminal is activated. . As a result, when the network scale becomes large, it is possible to cope with a situation in which information on peripheral terminals cannot be received and a reception slot of the own terminal cannot be determined.

  (1-3) A method of receiving a reception slot notification until the time derived from the time slot number indicated by the reception slot notification after receiving the reception slot notification for the first time. In this case, the reception slot notification reception period adjustment unit 32 determines the reception slot of the peripheral terminal from the time slot number of the reception slot notification first received from the peripheral terminal after starting up the own terminal, and the time when the reception slot becomes the reception slot Until now, the reception slot notification of the peripheral terminal is accepted. As a result, the reception time (that is, the waiting time) can be changed according to the reception slot of the peripheral terminal received first. For example, as the time slot number is smaller, the delay of the entire network can be reduced by reducing the waiting time.

  (1-4) A method of continuing reception of a reception slot notification until no reception slot notification is received for a predetermined time. In this case, the reception slot notification reception period adjustment unit 32 does not accept the reception slot notification when the reception slot notification cannot be received from the peripheral terminal even after a predetermined time has elapsed since the reception of the latest reception slot notification. As a result, the reception slot of the own terminal can be allocated after the situation of the peripheral terminal is sufficiently recognized.

  (1-5) A method of receiving a reception slot notification by a predetermined number of times. In this case, the reception slot notification reception period adjustment unit 32 counts the number of receptions of the reception slot notification, and accepts reception slot notifications of peripheral terminals until the number of receptions reaches a predetermined number.

  It should be noted that the method for determining the reception period of the reception slot notification is preferably unified in advance for the entire network. However, a determination method to be applied in each wireless terminal may be selected as necessary.

  The transmission destination terminal determination unit 33 determines the transmission destination terminal of the own terminal based on the reception slot notification from the peripheral terminal.

  As a method of determining the transmission destination terminal by the transmission destination terminal determination unit 33, any of the following methods can be applied.

  (2-1) A method of determining, as a transmission destination terminal, a terminal that has notified a reception slot with the earliest reception timing among reception slot notifications received by the terminal itself. In this case, the transmission destination terminal determination unit 33 determines the time slot number of each peripheral terminal based on the received reception slot notification of the peripheral terminal. Then, the terminal having the time slot with the smallest time slot number is determined as the transmission destination terminal.

  (2-2) A method of randomly selecting from the terminal that has transmitted the reception slot notification received by the terminal itself. In this case, when receiving the reception slot notification of the peripheral terminal, the transmission destination terminal determining unit 33 sets a terminal randomly selected from the peripheral terminals as the transmission destination terminal.

  (2-3) A method of including a transmission destination terminal (parent) in a reception slot notification and selecting a terminal having a small number of child terminals among transmission destination terminal candidates.

  The reception slot determination unit 34 assigns a time slot as a reception slot of the own terminal based on the reception slot notification from the peripheral terminal.

  As a receiving slot allocation method by the receiving slot determination unit 34, any of the following methods can be applied.

  (3-1) A method of allocating the reception slot of the own terminal immediately before the reception slot of the transmission destination terminal. In this case, the reception slot determination unit 33 confirms the time slot number indicating the reception slot of the transmission destination terminal determined by the transmission destination terminal determination unit 33, and immediately before the reception slot of the transmission destination terminal. To be assigned.

  (3-2) A method of assigning a time slot separated from the reception slot of the transmission destination terminal by a predetermined time (random time or fixed time) as the reception slot of the own terminal. In this case, the reception slot determination unit 33 assigns a time slot located at a time before a predetermined time as a reception slot based on the reception slot of the transmission destination terminal determined by the transmission destination terminal determination unit 33.

  (3-3) A method of assigning as a reception slot of the own terminal between the reception slot of the transmission destination terminal and the first slot (the time slot of number “1” in FIG. 2). In this case, the reception slot determination unit 34 determines the time slot number of the reception slot of the transmission destination terminal determined by the transmission destination terminal determination unit 33, and the time slot between the reception slot and the head slot of the transmission destination terminal. Is selected as the reception slot of the own terminal. At this time, the reception slot determination unit 34 may select a reception slot at random.

  (3-4) A method of selecting the reception slot of the terminal using a probability density function that increases the probability of selecting a slot closer to the reception slot of the transmission destination terminal.

  (3-5) In addition to any of the above methods (3-1) to (3-4), the time slot number of the peripheral terminal is excluded based on the reception slot notification from the peripheral terminal, and the result A method of assigning the receiving slot of the terminal itself.

  (3-6) In addition to any of the above methods (3-1) to (3-5), if there is a shortage of slots, the slowest slot (for example, the number “100” in FIG. 2) is set. A method that adds a function to go back and reuse slots.

(A-2) Operation of First Embodiment Next, processing in the wireless multi-hop network 10 of the first embodiment will be described with reference to the drawings. FIG. 5 is a flowchart illustrating processing in each wireless terminal according to the first embodiment.

  Hereinafter, the configuration of the wireless multi-hop network 10 illustrated in FIG. 1 will be described as an example. In FIG. 1B, a straight line in the drawing indicates a set of each wireless terminal and a transmission destination terminal, and an arrow direction indicates a data communication direction from each wireless terminal to the transmission destination terminal.

  Note that the wireless terminals 101 to 111 are assumed to be time-synchronized by some method and share a common time slot. Various methods can be used as a method of time synchronization, for example, a method of time synchronization between wireless terminals in advance, or information indicating the current time in reception slot notifications exchanged between neighboring wireless terminals. By performing the above, time synchronization can be performed at the same time as the network configuration.

  First, the coordinator 101 assigns the latest time slot (number “100” in FIG. 2) to the own terminal as a receiving slot, and notifies the peripheral terminals. This operation is a special operation performed only by the coordinator 101.

  The wireless terminals 102 and 103 that have received the reception slot notification transmitted by the coordinator 101 determine the transmission destination terminal and the reception slot of the local terminal based on the time slot number that is the reception slot of the coordinator 101. And a reception slot notification including the reception slot of the terminal itself is transmitted to the peripheral terminals.

  Further, in the wireless terminals 104 to 107 that have received the reception slots transmitted by the wireless terminals 102 and 103, similarly, the transmission destination terminal of the local terminal and the reception slot of the local terminal are determined and the reception slot notification is transmitted to the peripheral terminals. To do. By giving and receiving between such wireless terminals, processing can be performed on the entire wireless network.

  Next, processing in each of the wireless terminals 102 to 111 will be described in detail using a flowchart.

  In each of the wireless terminals 102 to 111, the reception period of the reception slot notification is adjusted (step S100), and if a reception slot notification is received from a peripheral terminal for a predetermined number or a predetermined time, based on the received reception slot notification A transmission destination terminal is determined (step S200). Next, a reception slot of the own terminal is determined (step S300), and a reception slot notification is transmitted to the peripheral terminals.

  Here, various methods as described above can be applied as a reception time determination method of the reception slot notification in each of the wireless terminals 102 to 111.

  The method (1-1) described above is effective in that the control of each wireless terminal is simplified. Further, in the method (1-2), when the method (1-1) is applied, there is a possibility that the reception slot of the own terminal may be determined without receiving the information of the peripheral terminal if the network scale becomes large. However, it is effective in that this can be solved. The method (1-3) is effective in that the waiting time can be converted by the reception slot of a terminal that can be a transmission destination terminal. For example, the delay of the entire network can be reduced by reducing the waiting time as the reception slot number is smaller. With the method (1-4), slot allocation can be performed after sufficiently recognizing surrounding conditions.

  Next, a method for determining a transmission destination terminal in each of the wireless terminals 102 to 111 will be described. Various methods as described above can be applied as a method of determining the destination terminal in each of the wireless terminals 102 to 111.

  In the description of the operation of the first embodiment, a case where (2-1) described above is used will be exemplified with reference to FIG.

  First, the reception slot of each peripheral terminal is confirmed based on the time slot number of the reception slot notification received from the peripheral terminal (step S201).

  Each of the wireless terminals 102 to 111 confirms the wireless terminal with the earliest reception timing (that is, the smallest time slot number) among the confirmed reception slots of each peripheral terminal (step S202), and transmits the wireless terminal to the transmission destination. The terminal is determined (step S203).

  According to the determination method of (2-1) described above, even when communication with the transmission destination terminal fails, a terminal having a reception slot later than that of the transmission destination terminal (that is, with a larger time slot number) exists in the vicinity. Can be transmitted to the terminal, which is effective in that an alternative route can be secured. This point will be described with reference to FIG.

  FIG. 7A shows a network configuration when the method (2-1) is not used. In FIG. 7A, for example, the wireless terminal 105 uses the wireless terminals 102 and 103 as peripheral terminals, but has determined that the wireless terminal 103 is a transmission destination terminal, and therefore performs transmission using the time slot number “97”. Shall. If communication with the slot number “97” fails for some reason, there is no wireless terminal that performs reception in the time slots of “98” and “99” around the wireless terminal 105. Cannot be transmitted, and will wait until the next “97” time slot.

  On the other hand, the wireless terminal 109 uses the wireless terminals 104 and 105 as peripheral terminals and the wireless terminal 104 as a transmission destination terminal among them, and therefore performs transmission using the time slot number “90”. Even if the communication with the time slot number “90” fails, the wireless terminal 105 that receives the time slot with the time slot “92” exists, so that communication can be performed with the wireless terminal 105. As described above, since transmission can be made to a terminal having a slow reception slot other than the transmission destination terminal, it is possible to secure an alternative route while minimizing an increase in delay. The method (2-3) described above is effective in avoiding the concentration of communication load on a specific terminal.

  Next, each of the wireless terminals 102 to 111 will be described with respect to a method for determining the reception slot of its own terminal. Various methods as described above can be applied as the reception slot determination method of each terminal by the wireless terminals 102 to 111.

  In the description of the operation of the first embodiment, a case where a method combining (3-2) and (3-5) described above is applied will be exemplified with reference to FIG.

  First, in each of the wireless terminals 102 to 111, the reception slot of the transmission destination terminal is confirmed (step S301), and the reception slot of the peripheral terminal is confirmed (step S302). Then, out of the slots separated from the receiving slot of the transmission destination terminal by a predetermined time, the receiving slots of the peripheral terminals are excluded (step S303), and the time slot to be the receiving slot of the own terminal is selected from the remaining time slots. (Step S304).

  FIG. 7A illustrates a network configuration when each wireless terminal 102 to 111 configures a network using a method in which (3-2) and (3-5) are combined.

  FIG. 1B illustrates a network configuration when each of the wireless terminals 102 to 111 configures a network using the method (3-2), and is compared with FIG. 7B. explain.

  For example, when the coordinator 101 transmits a reception slot notification, the wireless terminals 102 and 102 located around the coordinator 101 receive the reception slot notification of the coordinator 101.

  At this time, in the case of FIG. 1B, since the wireless terminals 102 and 103 apply the method (3-2), the same time slot number “97” is set as the reception slot of the own terminal. As a result, the communication timing from the wireless terminal 104 to the wireless terminal 102 and the communication timing from the wireless terminal 105 to the wireless terminal 103 are performed at the same time, and an interference signal is simultaneously generated on the dotted path in the drawing, so that communication is performed. It may be difficult to succeed.

  On the other hand, FIG. 7A shows an example in which (3-5) is used in addition to the above (3-2) as a method of determining the reception slot of the terminal itself. The dotted line in the figure indicates transmission / reception of the reception slot notification. First, after the coordinator 101 transmits the reception slot notification, the wireless terminal 103 secures the time slot number “97”, and the wireless terminal 103 transmits a reception slot notification with the number “97” to the peripheral terminals. Therefore, the wireless terminal 102 selects the reception slot of the own terminal from the time slot number other than the time slot number “97” and the time slot number “100” or less. By doing so, it is possible to avoid contention of reception slots as occurred in FIG.

  FIG. 7B shows a network configuration when the method (2-1) is applied as a method of selecting a transmission destination terminal. The number of relays from the wireless terminal 110 to the wireless terminal 101 is 3 times in FIG. 7B compared to 2 times in FIG. 7A, but the route is redundant. Many routes are secured. For example, the wireless terminal 110 can attempt to communicate with the wireless terminals 106 and 105 even if transmission to the wireless terminal 111 fails.

  The method (3-1) described above is effective in that the delay time until the reception slot of the own terminal is determined can be minimized. Further, the method (3-1) has a problem that packet collision is likely to occur as shown in FIG. 1B, for example, but in contrast to this, (3-2), (3- The method 3) can partially solve the problem (3-1). In addition, the methods (3-2) and (3-3) have a problem that the utilization efficiency of slots close to the reception slot of the coordinator 101 is lowered. However, the method (3-4) has this problem. Can be solved. The method (3-5) can reduce packet collision. The method (3-6) is effective when the network scale becomes large.

  Note that, as described above, various methods can be applied to the reception slot notification reception period determination method, the transmission destination terminal determination method, and the reception slot determination method. Various combination patterns can be applied to combination patterns used in the determination method, the transmission destination terminal determination method, and the reception slot determination method.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, the receiver is turned on at a terminal that relays packets, as compared with the conventional multi-hop network. Time can be limited to a specific slot, and power consumption can be greatly reduced. Since the conventional TDMA scheme determines the transmission timing of each terminal, the reception waiting time of a wireless terminal that can receive packets from a plurality of terminals has increased. This method can suppress an increase in power consumption.

  In addition, according to the first embodiment, there is a problem that communication delay generally increases when the TDMA method is used. However, in the first embodiment, the reception timing of each wireless terminal is the direction in which data flows (each terminal To the coordinator), it is possible to suppress an increase in power consumption and an increase in delay at the same time. Further, an increase in delay caused when communication fails can be significantly reduced by securing an alternative route.

(B) Second Embodiment Next, a wireless communication apparatus, method and program, and a wireless network according to a second embodiment of the present invention will be described with reference to the drawings.

  In the second embodiment, an embodiment in which the present invention is applied to a wireless terminal constituting a wireless network adopting a wireless multi-hop method will be described as an example.

(B-1) Configuration of Second Embodiment The second embodiment basically includes the functional configuration of the wireless terminal of the first embodiment shown in FIG. 3 and FIG. The detailed processing of the configuration requirements is different from that of the first embodiment. Therefore, in the second embodiment, processing of each component requirement different from that in the first embodiment will be described in detail with reference to FIGS. 3 and 4.

  Each wireless terminal 101 to 111 of the second embodiment exchanges terminal information with surrounding wireless terminals before assigning the receiving slot of the own terminal, and uses the terminal information obtained thereby, The reception slot is allocated.

  As with the first embodiment, each of the wireless terminals 101 to 111 according to the second embodiment has the configuration illustrated in FIG. 3, and as a functional unit included in the state management unit 306 as illustrated in FIG. A terminal information management unit 31, a reception slot notification reception period adjustment unit 32, a transmission destination terminal determination unit 33, and a reception slot determination unit 34 are provided.

  The peripheral terminal information management unit 31 exchanges terminal information with the peripheral terminal, and notifies the peripheral terminal of information related to the own terminal and manages information related to the peripheral terminal.

  Here, as a method of exchanging terminal information with peripheral terminals, the following method can be applied.

  In the first method, when the peripheral terminal information management unit 31 receives terminal information (first terminal information) from the peripheral terminal, the peripheral terminal information management unit 31 transmits the first terminal information including the terminal identification information of the own terminal to the peripheral terminal. It is.

  The second method is a method in which the peripheral terminal information management unit 31 transmits the first terminal information, and the first terminal information includes the number of relays from the coordinator 101. In this case, the coordinator 101 transmits “0” as the value of the number of relays included in the terminal information, and then the wireless terminal that has received the terminal information has the smallest number of relays among the received terminal information. This can be realized by adding “1” to the terminal and further transmitting terminal information.

  In the third method, the peripheral terminal information management unit 31 obtains the terminal identification information of the own terminal and the first terminal information obtained after transmission / reception of the first terminal information after transmission / reception of the first terminal information by the first or second method. This is a method for transmitting second terminal information including terminal identification information of a terminal.

  In the fourth method, the peripheral terminal information management unit 31 waits for a certain time after the transmission and reception of the first terminal information by the second method. When the terminal information is not received from the terminal having a higher number of relays than the own terminal during standby (that is, when the own terminal is located at the end of the network), and the second terminal information is once The second terminal information is transmitted only when it is not received.

  The terminal that has received the second terminal information transmits the second terminal information after waiting for a predetermined time. As a result, all the wireless terminals transmit the second terminal information once. The second terminal information can include information on peripheral terminals and terminal identification information of the transmission destination terminal of the own terminal. A terminal that has received the second terminal information can obtain the number of terminals (number of children) having each wireless terminal as a transmission destination terminal by accumulating the second terminal information.

  Similarly to the first embodiment, the reception slot notification reception period adjustment unit 32 determines the reception period of the reception slot notification, and applies the method described in the first embodiment.

  Furthermore, in the second embodiment, a method is applied in which the reception slot notification reception period adjustment unit 32 further determines the reception time of the following reception slot notification based on the first terminal information and / or the second terminal information. can do. The numbers in parentheses below are serial numbers of the numbers shown in the first embodiment.

  (1-6) A method of setting the standby time to be shorter as the number of peripheral terminals of the own terminal is larger (applicable to the first method to the fourth method as terminal information transmission / reception methods). In this case, the reception slot notification reception time adjustment unit 32 determines a set value in advance, calculates the number of peripheral terminals based on the first terminal information and / or the second terminal information, and the number of peripheral terminals sets the set value. If it exceeds, the waiting time is shortened, and if it is less than the set value, the waiting time is lengthened. Note that a plurality of setting values may be set and standby times corresponding to the respective setting values may be set, and the standby time may be determined according to the number of peripheral terminals.

  (1-7) A method of setting a waiting time to be shorter as the total number of peripheral terminals of the own terminal and the number of terminals adjacent to each peripheral terminal increases (in the case of the third and fourth methods as terminal information transmission / reception methods) Applicable). In this case, the reception slot notification reception period adjustment unit 32 calculates the number of peripheral terminals and the number of terminals adjacent to each peripheral terminal based on the second terminal information. If the total number of peripheral terminals and the number of adjacent terminals of each peripheral terminal exceeds a predetermined set value, the standby time is shortened, and if the total is less than the set value, the standby time is increased. To do. A plurality of setting values may be set.

  (1-8) A method in which the standby time is set shorter as the number of terminals that are children of the own terminal is larger (applicable to the case of the fourth method as a terminal information transmission / reception method). In this case, the reception slot notification reception period adjustment unit 32 calculates the number of terminals whose own terminal is the transmission destination terminal (that is, the number of child terminals) based on the second terminal information, and the number of child terminals of the own terminal However, when the preset value is exceeded, the standby time is shortened, and when the preset value is less than the preset value, the standby time is lengthened. A plurality of setting values may be set.

  (1-9) A method of arbitrarily combining the above methods (1-1) to (1-8).

  Similarly to the first embodiment, the transmission destination terminal determination unit 33 determines a transmission destination terminal, and applies the method described in the first embodiment.

  Furthermore, in the second embodiment, the transmission destination terminal determination unit 33 may further apply a method of determining a transmission destination terminal by the following method based on the first terminal information and / or the second terminal information. it can. The numbers in parentheses below are serial numbers of the numbers shown in the first embodiment.

  (2-7) A method of preferentially selecting a terminal having a small number of peripheral terminals (applicable to the case of the first method to the third method as the terminal information transmission / reception method). The transmission destination terminal determination unit 33 obtains the number of terminals adjacent to each peripheral terminal for each peripheral terminal based on the first terminal information and / or the second terminal information. Then, the peripheral terminal having the smallest number of terminals adjacent to each peripheral terminal is determined as the transmission destination terminal.

  (2-8) A method of selecting from terminals with the smallest number of transfers (number of hops) from the coordinator 101 (applicable to the second and third methods as terminal information transmission / reception methods). In this case, the destination terminal determination unit 33 obtains the number of transfers from the coordinator 101 to each peripheral terminal based on the first and second terminal information, and determines the terminal with the smallest number of transfers as the destination terminal. To do.

  (2-9) A method of arbitrarily combining the methods (2-1) to (2-8) above.

  Similarly to the first embodiment, the reception slot determination unit 34 determines the reception slot of its own terminal, and applies the method described in the first embodiment.

  Further, in the second embodiment, the reception slot determination unit 34 applies a method of determining the reception slot of the own terminal by the following method based on the first terminal information and / or the second terminal information. Can do. The numbers in parentheses below are serial numbers of the numbers shown in the first embodiment.

  (3-7) A method of determining by a probability density function in which a slot closer to a reception slot of a transmission destination terminal has a higher probability of being selected and a probability of selecting a slot closer to the reception slot is higher as the number of peripheral terminals is larger ( The terminal information transmission / reception method can be applied to the first method to the third method).

  (3-8) A method of selecting a slot that is distant from the reception slot of the transmission destination terminal by the number of terminals that are children of its own terminal (when the number of children is “0”, it is “1”) And can be applied to the case of the fourth method). In this case, the reception slot determination unit 34 calculates the number of child terminals of the own terminal based on the first terminal information and the second terminal information, and is separated from the reception slot of the transmission destination terminal by an amount corresponding to the number of child terminals. To determine the slot.

  (3-9) The number of terminals that are children of the own terminal from the slot that receives the earliest in the reception slot notification of the destination terminal or the reception slot from the peripheral terminal (when the child number is “0”, it is “1” ) A method of selecting slots separated by a distance (applicable to the case of the fourth method as a terminal information transmission / reception method). In this case, the reception slot determination unit 34 calculates the number of child terminals of the terminal based on the first terminal information and / or the second terminal information, and the earliest reception among the reception slots of the transmission destination terminal or each peripheral terminal. A slot separated from the slot by an amount corresponding to the number of child terminals is determined.

(B-2) Operation of Second Embodiment Next, processing in the wireless multi-hop network of the second embodiment will be described with reference to the drawings.

  FIG. 10 is a flowchart illustrating processing in each wireless terminal according to the second embodiment.

  First, before transmitting / receiving a reception slot notification, each of the wireless terminals 101 to 111 transmits / receives terminal information to collect information on peripheral terminals (step S400).

  When each of the wireless terminals 101 to 111 transmits / receives terminal information to / from the peripheral terminals by applying any of the first to fourth methods described above, the wireless terminals 101 to 111 receive the reception slots. A notification reception time determination process (step S100), a transmission destination terminal determination process (step S200), and a reception slot determination process of the own terminal (step S300) are performed.

  However, in the case where terminal information is transmitted and received by the fourth method, it is assumed that in each of the wireless terminals 101 to 111, the destination terminal selection process is completed when the second terminal information is transmitted.

  FIG. 9 is a configuration diagram illustrating a configuration of the wireless multi-hop network 20 according to the second embodiment. FIG. 9 shows an example in which terminal information is transmitted and received between wireless terminals by the fourth method, and the reception slot determination method according to (3-8) is performed.

  In FIG. 9, a straight line indicates a set of each wireless terminal and transmission destination terminal. The numbers in the circles shown in FIG. 9A indicate the number of transfers from the coordinator 101, and the numbers in the circles shown in FIG. 9B indicate the time slot numbers. Also, the dotted line in FIG. 9B indicates the reception slot notification.

  In this example, since the wireless terminal 103 has three child terminals (wireless terminals 105, 106, 107), the time slot number “97” separated from the reception slot of the parent coordinator 101 by “4” is set. Secure. Then, if there is reception at the time slot number “97”, the wireless terminal 103 also performs reception at the time slot number “98”.

  On the other hand, the reception slot notification transmitted by the wireless terminal 103 can include the presence of three child terminals. As a result, the child terminal recognizes that the wireless terminal 103 has secured three time slots of time slot numbers “97” to “99”, and even when communication using the time slot number “97” fails. Retransmission can be performed.

  However, when performing the above method, there are situations in which packet collision cannot be avoided. In FIG. 9B, the dotted line indicates the path where packet collision occurs.

  In FIG. 9B, the wireless terminal 110 and the wireless terminal 111 transmit data to the wireless terminal 105 and the wireless terminal 106 with the same time slot number “96”. These two transmission signals can be received by both the wireless terminals 105 and 106, and packet collision occurs.

  FIG. 11A shows an example in which terminal information is transmitted and received by the fourth method, and the reception slot determination method by the method (3-9) is performed. In FIG. 11A, a dotted line indicates a transmission / reception relationship of a reception slot notification that affects slot allocation.

  Upon receiving the reception slot notification from the wireless terminal 102, the wireless terminal 103 avoids the time slot number “99” and uses the time slot numbers “96”, “97”, and “98”. By using the slot allocation result of the peripheral terminal, it can be seen that the adjacent terminals can avoid using the same slot and packet collision can be avoided.

  In FIG. 11B, terminal information is transmitted and received by the fourth method, a reception slot determination method by the method (3-9) is performed, and the waiting time of each wireless terminal is determined by the method (1-8) An example in the case of setting using is shown.

  Comparing the case of FIG. 11B and the case of FIG. 11A, the order of securing the reception slots of the wireless terminal 102 and the wireless terminal 103 is reversed. That is, in FIG. 11B, the wireless terminal 103 with a large number of children secures the reception slot first.

  As a result, the delay of the entire network can be reduced. That is, in FIG. 11 (a), time slots of time slot numbers “100” to “89” are assigned to the entire network, whereas in FIG. 11 (b), time slot numbers “100” to “89” are assigned. The allocation up to “91” is good, and the network delay can be reduced.

(B-3) Effects of Second Embodiment As described above, according to the second embodiment, the following effects can be obtained in addition to the effects described in the first embodiment.

  According to the second embodiment, packet collisions can be further reduced as compared with the first embodiment by assigning reception slots after collecting information on peripheral terminals in advance. In particular, by establishing the parent-child relationship of each terminal in advance, it is possible to secure the number of reception slots corresponding to the number of child terminals, and to minimize packet collisions even in networks with high communication frequencies. It becomes possible.

(C) Other Embodiments (C-1) In the first embodiment, the number of transfers from the coordinator 101 may be added to the reception slot notification transmitted by each wireless terminal. Specifically, the number obtained by adding “1” to the smallest number of transfers included in the received slot notification received until the reception slot notification is transmitted is set as the number of transfers of the own terminal. Also, for example, the number of transfers added by “1” to the number of transfers included in the reception slot notification of the terminal selected as the destination terminal is set as the number of times of transfer. This can be realized.

(C-2) As described above, the following processing may be performed as a transmission destination terminal determination method by including the number of transfers in the reception slot notification.

(2-5) A method of selecting from the wireless terminals with the smallest number of transfers in the reception slot notification received by the wireless terminal.

(2-6) A method in which the method (2-5) is added to the methods (2-1) to (2-4).

  By adopting the configuration as described above, it is possible to avoid redundant transfer paths.

It is a block diagram which shows the structure of the network of 1st Embodiment. It is explanatory drawing explaining the time slot of 1st Embodiment. It is an internal block diagram which shows the internal structure of the radio | wireless terminal of 1st Embodiment. It is a functional block diagram which shows the function structure of the state management part of 1st Embodiment. It is a flowchart which shows the process in each radio | wireless terminal of 1st Embodiment. It is a flowchart which shows the determination process of the transmission destination terminal of 1st Embodiment. It is a network block diagram for demonstrating the determination process of the transmission destination terminal of 1st Embodiment. It is a flowchart which shows the determination process of the reception slot notification of the own terminal of 1st Embodiment. It is a block diagram which shows the structure of the network of 2nd Embodiment. It is a flowchart which shows the process in each radio | wireless terminal of 2nd Embodiment. It is a network block diagram which shows the determination process of the receiving slot of 2nd Embodiment.

Explanation of symbols

  101 to 111: wireless terminal, 301: antenna unit, 302 ... receiving circuit unit, 303 ... transmitting circuit unit, 304 ... received data processing unit, 305 ... transmission data generating unit, 306 ... state management unit, 31 ... peripheral terminal information management 32, reception slot notification reception time adjustment unit, 33 ... transmission destination terminal determination unit, 34 ... reception slot determination unit, 10 and 20 ... wireless multi-hop network.

Claims (15)

In a wireless communication device provided in each of a plurality of wireless terminals constituting a wireless network,
A reception slot information communication means for transmitting reception slot information indicating a reception period of the own terminal to surrounding wireless terminals;
Based on the reception slot information from the peripheral wireless terminal, a transmission destination terminal determining means for determining the transmission destination terminal of the local terminal from the peripheral wireless terminals;
Based on the receiving slot information of the destination terminal determined by the destination terminal determining means, receiving slot determining means for determining the receiving slot of the own terminal before the receiving slot of the destination terminal;
A wireless communication device comprising: transfer processing means for performing a data signal transfer process in a reception slot of the terminal itself.   2. The wireless communication apparatus according to claim 1, wherein the reception slot determining means probabilistically selects a reception slot prior to the reception slot of the transmission destination terminal.   3. The radio communication apparatus according to claim 2, wherein the reception slot determining means uses a probability function for selecting a slot that reduces a time difference from the reception slot of the destination terminal.   2. The radio communication apparatus according to claim 1, wherein the reception slot determining means selects a slot that is separated from a reception slot of the destination terminal by a predetermined time. Terminal information communication means for transferring terminal information to and from surrounding wireless terminals;
Terminal information management means for determining the presence status of wireless terminals existing in the vicinity based on the terminal information from the peripheral wireless terminals, and
5. The wireless communication apparatus according to claim 1, wherein the reception slot determining means determines a reception slot of the terminal according to a situation of wireless terminals existing in the vicinity.   The reception slot determining means uses a function for selecting a slot whose time difference from the reception slot of the destination terminal becomes smaller as the number of wireless terminals that can directly communicate with the own terminal increases. Item 6. The wireless communication device according to Item 5.   The reception slot determining means changes the delay time from the determination of the transmission destination terminal to the reception slot of the own terminal according to the number of wireless terminals that can directly communicate with the own terminal. The wireless communication device according to 5 or 6. The terminal information management means determines the number of child terminals whose destination is the own terminal based on the received terminal information,
6. The radio according to claim 5, wherein the reception slot determining means uses a function for selecting a slot whose time difference from the reception slot of the destination terminal becomes smaller as the number of child terminals increases. Communication device.   6. The radio communication apparatus according to claim 5, wherein the reception slot determining means selects a slot that is separated from the reception slot of the transmission destination terminal by the number of slots corresponding to the number of child terminals.   10. The transmission destination terminal determining means determines a transmission destination terminal that has the reception slot that is set at the earliest position among the received reception slot information. Any one of the radio | wireless communication apparatuses.   10. The destination terminal determining means determines a destination terminal based on the terminal information from neighboring wireless terminals before determining a receiving slot. A wireless communication device according to 1.   The reception slot determining means also determines the reception slot of the peripheral wireless terminal based on the reception slot information of the peripheral wireless terminal, and determines the reception slot of the own terminal using the determination result. The wireless communication apparatus according to claim 1. In a wireless communication method of a wireless communication device provided in each of a plurality of wireless terminals constituting a wireless network,
The wireless communication apparatus includes a reception slot information communication unit, a transmission destination terminal determination unit, a reception slot determination unit, and a transfer processing unit.
A receiving slot information communication step in which the receiving slot information communication means exchanges receiving slot information indicating a receiving period of the own terminal with surrounding wireless terminals;
The destination terminal determining means, based on the reception slot information from the surrounding wireless terminal, a destination terminal determining step of determining the destination terminal of the own terminal from the surrounding wireless terminals;
The receiving slot determining means determines the receiving slot of its own terminal before the receiving slot of the destination terminal based on the receiving slot information of the destination terminal determined by the destination terminal determining means. Process,
A wireless communication method, wherein the transfer processing means includes a transfer processing step of performing a data signal transfer process in a reception slot of the terminal itself. In a wireless communication program of a wireless communication device provided in each of a plurality of wireless terminals constituting a wireless network,
Computer
A receiving slot information communication means for transmitting / receiving receiving slot information indicating a receiving period of the own terminal to / from peripheral wireless terminals;
A destination terminal determining means for determining a destination terminal of the own terminal from among the peripheral wireless terminals based on the reception slot information from the peripheral wireless terminals;
A receiving slot determining means for determining a receiving slot of its own terminal before a receiving slot of the destination terminal based on the receiving slot information of the destination terminal determined by the destination terminal determining means;
A wireless communication program that functions as transfer processing means for performing a transfer process of a data signal in a reception slot of its own terminal.   In a wireless network configured with a plurality of wireless terminals, each of the wireless terminals includes the wireless communication device according to any one of claims 1 to 12 that exchanges information between the wireless terminals. A wireless network characterized by that.

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