JP2010177842A - Radio communication method and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication method and a radio communication system that can enhance efficiency of radio communication. <P>SOLUTION: The radio communication system 1 includes at least one control station 6 and a plurality of radio terminals (devices) 10 and 20. In the radio communication system 1, the pair of the devices 10 and 20 perform radio communication using a directional beam under the control of the control station 5. Respective procedures of the radio communication method are so set that when radio communication is established, a time slot common to both of the pair of the devices is allocated to the respective devices. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication method for a pair of wireless terminals to perform wireless communication in a wireless communication system including a plurality of wireless terminals (hereinafter also referred to as “devices”).

  A time division multiple access (TDMA) scheme has been proposed for wireless communication performed in a wireless communication system including a plurality of wireless terminals. In order to perform wireless communication (for example, piconet communication) by the TDMA system, for example, one control station (for example, piconet coordinator (PNC)) is arranged in the wireless communication system (for example, refer to Patent Document 1). .

  In such a wireless communication system, the control station transmits a beacon as a control signal to a plurality of wireless terminals. Then, the wireless terminal that has successfully received the transmitted beacon performs an association with the control station. As a result, a piconet star topology is formed. Thereafter, as shown in FIG. 10, the control station assigns a time slot to each wireless terminal so that wireless communication is established between a pair of wireless terminals among the associated wireless terminals.

  By the way, some wireless terminals use directional beams (radio waves) having directivity in a plurality of directions. When such a wireless terminal is handled in the wireless communication system as described above, in order for wireless terminals (a pair of wireless terminals) to perform wireless communication, the directivity of the directional beam is previously set between the wireless terminals. In order to make it consistent, it is necessary to control the adjustment of directivity.

  As described above, when a time slot is assigned to each wireless terminal even though directivity control is performed in this way, the assigned time slot matches between a pair of wireless terminals. Will result in a time that is not. Then, wireless communication cannot be performed by this amount of time, and the efficiency of wireless communication is deteriorated. In the wireless communication system as described above, a time slot is assigned to each wireless terminal even when there is no interference in the beam in the communication channel between a pair of wireless terminals. As a result, there is a time during which wireless communication cannot be performed even though the beam is not interfering, and the efficiency of wireless communication is poor.

  Furthermore, in the wireless communication system as described above, since the control station needs to assign time slots to wireless terminals, the processing load on the control station is large.

JP 2008-219554 A

  Therefore, the main object of the present invention is to provide a wireless communication method and a wireless communication system that can increase the efficiency of wireless communication. Another object of the present invention is to provide a control station, a wireless terminal, a wireless communication control program, and a wireless communication program suitable for such a wireless communication method and a wireless communication system.

  Another object of the present invention is to provide a wireless communication method, a wireless communication system, and the like that can reduce the processing load on a control station included in the wireless communication system.

  The present invention basically relates to a wireless communication method and the like. According to the wireless communication method of the present invention, wireless communication using a directional beam is performed between a pair of wireless terminals under the control of the control station in a wireless communication system having at least one control station and a plurality of wireless terminals. Done.

  In this wireless communication method, when wireless communication is established between a pair of wireless terminals, a time slot common to both the pair of wireless terminals is assigned under the control of the control station. It has become. A plurality of methods can be considered as a method for assigning time time slots, and these methods can be obtained by appropriately setting each procedure of the wireless communication method. Thus, by assigning a common time slot to a pair of wireless terminals, it is not necessary to individually assign a time slot to each wireless terminal. As a result, the efficiency of wireless communication using a directional beam can be increased.

  In another aspect of the present invention, in wireless communication, the control station sequentially executes a time division step and a transmission step. Specifically, in the time division step, the control station assigns a time slot necessary for a pair of wireless terminals to perform wireless communication so as to be common to both the pair of wireless terminals. In the subsequent transmission step, the control station transmits, to each of the pair of wireless terminals, a common control signal including information on time slots assigned so as to be common to both of the pair of wireless terminals. The pair of wireless terminals that have received the common control signal perform wireless communication using radio waves having directivity in a plurality of directions with each other in the time slot assigned in the time division step.

  Thus, according to this aspect, it is possible to assign time slots so that they are common to both of a pair of wireless terminals. As a result, a pair of wireless terminals can perform wireless communication in the same time slot. As a result, the communication efficiency can be improved as compared with the case where time slots are individually assigned to the respective wireless terminals.

  In another aspect of the present invention, the wireless communication method further includes a request step in which each of the plurality of wireless terminals transmits a communication request for performing wireless communication to the control station. In this case, in the time division step, the control station selects a pair of wireless terminals that should perform wireless communication in the communication step from the plurality of wireless terminals based on the requests transmitted from the plurality of wireless terminals in the request step. , Grasp. As a result, the control station can easily grasp a pair of wireless terminals, and the processing load on the control station can be reduced.

  Further, in a more preferred aspect of the present invention, the communication request is a request for requesting allocation of a time slot common to a wireless terminal that requests wireless communication. As a result, the control station can easily grasp a pair of wireless terminals as well as a time slot. That is, the processing load on the control station is reduced.

  Alternatively, in another aspect of the present invention, in the time division step, a time slot necessary for a pair of wireless terminals to perform wireless communication is only assigned so as to be common to both the pair of wireless terminals. Instead, a time slot required for wireless communication by a wireless terminal pair different from the pair of wireless terminals is assigned in common with the assigned time slot. In this case, the common control signal is transmitted to each of the pair of wireless terminals and another pair of wireless terminals in the transmission step. Thus, another wireless terminal pair can perform wireless communication in the same time slot. As a result, the efficiency of wireless communication can be further increased.

  In still another aspect of the present invention, each of a plurality of wireless terminals constituting a wireless communication system has directivity indicating directivity of a directional beam with a wireless terminal capable of performing wireless communication. It is configured to be able to perform control to adjust. In this case, in the wireless communication method as described above, the directivity control step is executed. This directivity control step is a step for performing directivity control so that a pair of wireless terminals can perform wireless communication with each other. In this aspect, the directivity control step is executed after the transmission step. That is, in this aspect, directivity control is performed after a device pair is determined based on the control signal. Therefore, each device can easily control the directivity of the directional beam. As a result, the processing load on each device can be reduced.

  Alternatively, in still another aspect of the present invention, the directivity control step is executed before the transmission step. In this case, when the control station uses information on directivity in the directivity control step, the device pair can be easily grasped, and the processing load on the control station can be reduced.

  In another aspect of the present invention, the control station is configured to be able to transmit a control signal for controlling wireless communication to a plurality of wireless terminals. In addition, each of the plurality of wireless terminals is configured to be able to perform control for adjusting the directivity indicating the directionality of the beam with a wireless terminal capable of performing wireless communication. In this case, in the wireless communication method as described above, a directivity control step, a step of acquiring consistency information, and a determination step are executed.

  Here, the directivity control step is a step of performing directivity control so that a pair of wireless terminals can perform wireless communication with each other. The step of acquiring directivity information is a step in which the control station acquires directivity information related to directivity control by a pair of wireless terminals in the directivity control step. The determination step is a step in which the control station determines whether or not the directivity is matched between the pair of wireless terminals based on the directivity information.

  When it is determined in the above determination step that the directivity is matched between the pair of wireless terminals, the control station omits transmission of the control signal. Thereby, the wireless communication performed by the pair of wireless terminals is substantially permitted by the control station. Furthermore, the time required for the wireless communication is substantially allocated as a time slot common to both the pair of wireless terminals. Therefore, in this aspect, the processing load on the control station can be greatly reduced.

  Alternatively, in another aspect of the present invention, in the wireless communication method as described above, a directivity control step similar to the above, a step of acquiring directivity information similar to the above, and a determination step similar to the above are executed. . However, in this aspect, when it is determined in the determination step that the directivity is matched between the pair of wireless terminals, the control station performs wireless communication performed by the pair of wireless terminals as information on the time slot. In the transmission step, transmission of a control signal including information indicating that communication is permitted is performed. This also substantially assigns the time required for wireless communication as a time slot common to both of the pair of wireless terminals. In addition, since the control signal includes information indicating acceptance, the wireless terminal can easily determine whether or not to continue the wireless communication.

  In another aspect of the present invention, the wireless communication as described above is piconet communication. In this case, the control station is a coordinator that coordinates piconet communication by transmitting a control signal as a beacon to a plurality of wireless terminals. As a result, it can be easily implemented in a wireless communication system.

  Another aspect of the present invention is a wireless communication system. The wireless communication system of the present invention includes a plurality of wireless terminals. And in this radio | wireless communications system, the process equivalent to the process (step) which concerns on any one of the radio | wireless communication methods mentioned above is performed. Therefore, an effect equivalent to the effect described above can be achieved.

  Yet another aspect of the present invention is a wireless terminal. When the wireless communication system includes a control station, the wireless terminal according to the present invention performs part of the processing (steps) related to any of the wireless communication methods described above according to the control of the control station. Therefore, the wireless terminal of the present invention contributes to the effects described above. In the case where the wireless communication system includes a control station, even when the control station is not substantially involved in the wireless terminal of the present invention, the control station can perform wireless communication between the wireless terminal of the present invention and another wireless terminal. As long as this is accepted, a time slot common to both wireless terminals can be substantially allocated to the wireless terminal of the present invention.

  Still another aspect of the present invention is a wireless communication control program readable by the control station or a wireless communication program readable by the wireless terminal. The processes corresponding to these programs correspond to a part of the processes (steps) related to any one of the above-described wireless communication methods. Therefore, these programs also contribute to the effects described above.

  According to the present invention, in a wireless communication system that performs wireless communication using a directional beam, the same time slot can be assigned to a pair of wireless terminals under the control of the control station. . By doing in this way, compared with the case where a control station allocates a time slot individually with respect to each radio | wireless terminal, the efficiency of radio | wireless communication can be improved.

  Further, according to the present invention, it is possible to share information by appropriately setting each procedure of the wireless communication method. By sharing information, it is possible to reduce the processing load on the control station and the devices that constitute the wireless communication system.

  Also, in the present invention, the same time slot can be assigned to another wireless terminal, and in this way, the efficiency of wireless communication can be further increased.

It is a figure which shows the structural example of the radio | wireless communications system 1 which concerns on the form (1st aspect) for implementing this invention. FIG. 2 is a diagram useful in explaining the directivity of the directional beam of the device (wireless terminal) shown in FIG. FIG. 3 is a diagram (flow chart) showing a procedure of wireless communication executed in the wireless communication system 1 of FIG. FIG. 4 is a diagram (flow chart) showing in detail the procedure of the association process executed in step S10 of FIG. FIG. 5 is a diagram for explaining the process of FIG. 3 in detail. FIG. 5A is a diagram schematically showing the structure of the superframe in the process of FIG. 3, and FIG. FIG. 5 is a diagram for explaining an example in which no interference occurs in a directional beam in a plurality of devices. FIG. 6 is a diagram (flow chart) for explaining the second aspect of the present invention. FIG. 7 is a diagram (flow chart) for explaining the third aspect of the present invention. FIG. 8 is a diagram (flow chart) for explaining the fourth aspect of the present invention. FIG. 9 is a diagram for explaining the sixth aspect of the present invention, FIG. 9 (a) is a diagram showing the flow of data in the radio communication system 1 ′, and FIG. It is a figure which shows typically the structure of the super frame in the process of a 6th aspect. FIG. 10 is a diagram schematically showing a superframe structure when time slots are assigned to each device.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the form described below is an example, and can be appropriately modified within a range obvious to those skilled in the art.

  FIG. 1 is a diagram illustrating a configuration example of a wireless communication system 1 according to an embodiment (first aspect) for carrying out the present invention. As shown in FIG. 1, the wireless communication system 1 includes one control station 5 and a first device 10 and a second device 20 that are wireless terminals. The system 1 includes two devices 10 and 20 as wireless terminals, but may further include another wireless terminal (a third device or a fourth device). In the wireless communication system 1, wireless communication using a directional beam is performed between a pair of devices. Such wireless communication can be based on, for example, IEEE 802.15.3c (millimeter wave WPAN standard) which is a communication standard. Therefore, the wireless communication system 1 is configured to perform, for example, piconet communication using the TDMA system.

  The control station 5 is for controlling wireless communication between devices. The control station 5 is configured to be able to send a control signal for controlling wireless communication to a plurality of devices in the wireless communication system 1. As the control station 5, a piconet coordinator (PNC) can be used. Therefore, in this first aspect, a piconet coordinator will be described as an example.

  The first device 10 and the second device 20 are wireless terminals configured to transmit radio waves (beams) necessary for wireless communication in a predetermined direction. An example of the beam transmitted by each device is shown in FIG. As shown in FIG. 2, the beam transmitted by each device is a directional beam having directivity in a plurality of directions. The directivity indicates the directionality of the transmitted beam. In this first mode, the directional beam has directivity in four directions (a direction, b direction, c direction, d direction) as shown in FIG. And such a radio | wireless terminal can perform the radio | wireless communication between other radio | wireless terminals using a directional beam, or can receive the control signal from the control station 5 now. . Each wireless terminal is configured to operate according to the control signal when it receives the control signal. Each device is configured to be able to perform control to adjust the directivity of the directional beam so that wireless communication can be performed with other devices.

  Next, the procedure of wireless communication executed in the wireless communication system 1 as shown in FIG. 1 will be described with reference to FIG. S in FIG. 3 indicates a step number.

  In FIG. 3, first, in step S10, association processing is performed between the control station 5 (PNC) and each wireless terminal (each device). If this association is successful, each device enters the control of the control station. Thereby, at least synchronization between the control station 5 and each device and synchronization between devices are achieved.

  Details of the association process are shown in FIG. As shown in FIG. 4, first, the control station 5 transmits a beacon as a control signal toward a plurality of devices (step S110). Here, a beacon is a beam transmitted at the initial stage of a superframe (beacon time slot) shown in FIG. 5A, and is a beam that can be transmitted only by the control station 5. This beacon contains various information. The control station 5 is configured to send out this beacon every time a predetermined period elapses, and FIGS. 3 to 5 (a) show one beacon transmission.

  Each device in the wireless communication system 1 receives a beacon from the control station 5 (step S120). However, there may be a device that fails to receive the control signal. The device that has successfully received the beacon transmits an association request to the control station 5 (step S130). This association request includes information about the device.

  Subsequently, the control station 5 receives an association request from each device (step S140). When the control station 5 approves the association request from a certain device, the control station 5 transmits an association approval message to the device as an association response (step S150). When the corresponding device receives the association response (step S160), the association is completed between the control station 5 and the device.

  When the wireless communication (data communication) is performed between the pair of devices after the association is completed as described above, the processing after step S20 in FIG. 3 is performed.

  Therefore, when it is necessary for each associated device to perform data communication with another device (communication partner), it is determined whether a communication channel can be formed with that device. To grasp. Each device transmits a communication request to the control station 5 (PNC) in order to perform wireless communication with the communication partner (step S20).

  This communication request includes information on a device (communication partner) that needs to perform data communication. As information on the communication partner, information on the reception intensity when receiving the directional beam of the communication partner, or the directivity of the own directional beam when receiving (for example, a direction to d as shown in FIG. 2) Information on the direction) is preferably included. Thereby, each device and the control station 5 can obtain information (distance and direction) regarding the relative position of the device pair. The communication request preferably includes information on a directional beam pattern (direction indicating directivity) of each device.

  Then, the control station 5 receives a communication request from each associated device (step S22). As a result, communication requests from a plurality of devices are collected in the control station 5. Then, the control station 5 grasps which device and which device are going to perform wireless communication with each other from the information regarding the communication partner included in the communication request (step S24). That is, the control station 5 grasps the communication target device pair. If the communication request includes information on the pattern of the directional beam, the control station 5 uses the information to determine how the directional beam pattern overlaps between the device pairs, that is, how the communication channel is formed. Can be guessed.

  Here, in the first mode, the control station 5 grasps whether or not interference occurs in the directional beam in the communication channel formed by each device pair. In the example shown in FIG. 5B, there is no interference between the pair of directional beams of the first device 10 and the second device 20 and the pair of directional beams of the third device and the fourth device. I understand.

  Subsequently, the control station 5 assigns a time slot (communication time slot) as a time during which wireless communication is possible for each pair of communication target devices (step S26). For this reason, the same time slot is assigned to the two devices constituting the device pair. Here, to give an example, as shown in FIG. 5A, the first device 10 and the second device 20 are assigned the same time slot. By the way, the time slot divides the time corresponding to one superframe (time division). Therefore, allocating the same time slot corresponds to sharing the time slot of the first device 10 and the time slot of the second device 20 in one superframe.

  Further, the control station 5 is configured to assign the same time slot to a device pair in which no interference occurs in the directional beam. An example of such allocation is also shown in FIG. 5A. Specifically, the time slot of the third device and the time slot of the fourth device are the first device 10 and the second device 20. The same is true for the time slots.

  As described above, when the time slot assignment is completed, the control station 5 includes information on the time slot in the control signal and transmits the information to each device (step S28). Here, as described above, since the same time slot is assigned to the first device 10 and the second device 20, the same control signal (common control signal) is transmitted. In addition, it is preferable that the information regarding a communicating party is contained in the control signal. As a result, the device that has received the control signal can easily identify the communication partner. In other words, the control station 5 has declared approval for a request to request allocation of the same time slot related to a communication request by transmitting a common control signal to both device pairs. I can say. In other words, when the control station 5 does not declare approval, it corresponds to a case where the communication request is rejected as a result of judging that the same time slot cannot be used.

  When each device receives a control signal from the control station 5, it operates according to the control signal. Specifically, wireless communication with another device is attempted during the time slot included in the control signal. If the control signal contains information about the communication partner, data communication with the communication partner is attempted.

  Subsequently, each device controls the directivity of the directional beam as necessary (step S30). For example, when a communication partner is determined, each device adjusts or changes the direction of the directional beam so that the overlap between the communication partner and the directional beam becomes large. In addition, each device adjusts or changes the direction of the directional beam so that the degree of the interference is reduced when interference occurs in the overlap of the directional beam with the communication partner. Note that this processing is omitted when the directional beam overlap is sufficiently large. If the direction of the directional beam is not adjusted so as to increase the overlap of the directional beams even if the direction of the directional beam is adjusted, the process is terminated without performing the subsequent data communication process. In this first aspect, directivity control is performed after the device pair is determined based on the control signal, so that each device only has to direct the directional beam toward the communication partner. Control can be easily performed. As a result, the processing load on each device can be reduced.

  Each device performs data communication with the communication partner device using a directional beam (step S40). Data communication is performed over a time corresponding to the time slot of the control signal. In the example described above, since the first device 10 and the second device 20 have a common time slot, bidirectional data communication is performed between them for the time corresponding to this time slot. Further, in the above-described example, data communication between the third device and the fourth device is also performed in parallel at the time corresponding to the same time slot as the data communication between the first device 10 and the second device 20 (FIG. 5). (See (b)).

  As described above, wireless communication is performed for each device pair in each time slot. As described above, since the same time slot is assigned to the first device 10 and the second device 20, wireless communication between the two devices proceeds smoothly. In particular, as shown in FIG. 5A, when there is no interference in the directional beam, wireless communication between devices proceeds very smoothly. For this reason, according to the first aspect, communication efficiency between devices is high. In the first mode, the control station 5 can reduce the processing load by utilizing information included in the communication request from each device.

  Here, the case where interference from other sources does not occur in the directional beam will be examined in more detail. For example, as shown in FIG. 10, when the time slot assigned to the first device 10 and the time slot assigned to the second device 20 are different, wireless communication is performed only in one direction in each time slot. Can not do. For this reason, in order for both devices to perform data communication with each other, two time slots are required. On the other hand, as shown in FIG. 5B, when a time slot common to the first device 10 and the second device 20 is assigned, both the time slots (that is, one time slot) Wireless communication can be performed. That is, according to this aspect, the communication efficiency between devices is increased to about twice. In addition, in this aspect, two time slots are not required, so that wireless communication between both parties is blocked until the communication partner's time slot arrives or within the time corresponding to the communication partner's time slot. The possibility of being done can be eliminated. Furthermore, in this aspect, since two time slots are not required, the time corresponding to one superframe can be shortened, or the time corresponding to each time slot in one superframe can be reduced. Can be long.

  In step S30 of FIG. 3, it is preferable to confirm the communication quality between the device pairs before performing directivity control. Thereby, it is possible to easily determine how much directivity control should be performed or whether directivity control may be performed. Moreover, it is preferable to confirm the communication quality between device pairs after performing directivity control. As a result, it is possible to easily determine whether or not the directivity control is successful. If directivity control is not successful, wireless communication in step S40 may not be performed, and directivity control may be attempted again. For the same purpose, the communication quality may be confirmed before performing wireless communication in step S50 of FIG. It is also possible to arbitrarily combine the above-described communication quality confirmation before directivity control, directivity control confirmation after directivity control, and directivity control confirmation before wireless communication.

  In the first mode described above, among the processes shown in FIG. 3, the processes in steps S120, S130, 160, S20, S30, and S40 are performed by each device, but are executed by at least one device of the device pair. do it. Even in this case, the above-described effects can be obtained.

  Further, in the first aspect described above, in order to acquire information necessary for the control station 5 to grasp the device pair to be communicated, the communication request transmitted from each device includes information on the communication partner, directivity. Information such as information on beam patterns is included. Instead, the control station 5 monitors the communication between devices and the directivity control of each device, so that information on the communication partner, information on the directivity of the directional beam (directivity information), etc. Information necessary for grasping the communication target device pair may be acquired. In this case, since it is not necessary to include such information in the communication request, the processing load on each device is reduced.

  Next, another mode (second mode) for carrying out the present invention will be described. In the first aspect, the directivity control process (S30) is performed after the communication request process (S20). On the other hand, this 2nd aspect performs a directivity control process before a communication request process. A flowchart corresponding to the wireless communication method according to the second aspect is shown in FIG. In the second mode (and third to sixth modes described later), the description of the same parts as those in the first mode is omitted because it is redundant.

  As shown in FIG. 6, in the second mode, each device performs control for adjusting directivity in the directivity control step (S20), so that the directional beam overlaps with other devices. After reaching a large state, a communication request is transmitted to the control station 5 in step S30. Then, the control station 5 can grasp the device pair based on the communication request in step S34, and only needs to ensure that a common time slot is assigned to the device pair (step S36). . As a result, the processing load on the control station 5 is reduced.

  In the second mode, the control station 5 uses the time slot even when the device pair in which the overlapping of the directional beams is large is not controlled by the control signal, that is, wireless communication between the device pair is performed. To tolerate. In this approval, the control station 5 first performs the time slot allocation process (S36) only to the extent necessary for the “acceptance”. Thereby, the processing load of the control station 5 is reduced. Subsequently, in step S38, the control station 5 includes information indicating acceptance as information related to the time slot in the control signal, and transmits the control signal to both of the device pairs. As described above, the fact that the control station 5 can accept the wireless communication between the device pair means that the communication request from each device (S30) requires that a time slot common to the wireless terminal that requests the wireless communication is allocated. It is nothing but a request.

  On the other hand, on the device side, the operation necessary for the wireless communication is continued even while waiting for the wireless communication to be accepted by the control station 5. In the meantime, a control signal including acceptance is received from the control station 5. By the way, also in the second mode as described above, a period in which a device pair having a large overlap of directional beams uses a time slot is a time slot allocated (accepted) by the control station 5. It can be said that it is equivalent. That is, it can be said that each device is under the control of the control station 5.

  In the second mode, each device stops wireless communication with another device if it does not receive a control signal including information indicating acceptance from the control station 5 even after a predetermined period. It is preferable that it is comprised. Thus, each device can easily determine whether or not to continue wireless communication with the device.

  Next, another mode (third mode) for carrying out the present invention will be described. In the second aspect, the control station 5 accepts wireless communication between a device pair based on a communication request from the device. Also in this third mode, the control station 5 accepts wireless communication between the device pair. However, in this aspect, even if the control station 5 accepts the wireless communication between the device pair, the control station 5 is configured to omit the transmission of a control signal including the approval notice. FIG. 7 shows a flowchart of the wireless communication method according to the third aspect.

  As shown in FIG. 7, in the third mode, the control station 5 accepts wireless communication between the device pair based on the information about the communication partner included in the communication request from the device (step S34). Then, the control station 5 omits the transmission of the control signal including the approval. Thereby, the processing load of the control station 5 is greatly reduced. In addition, since the control signal is not transmitted from the control station 5 to both of the corresponding device pairs, it is not necessary to wait for reception of the control signal, and processing when the control signal is received is eliminated. This reduces the processing load on the device.

  In the third mode, when the control station 5 receives a communication request from a device whose directional beam overlap is not large, for example, the control station 5 performs processing in the procedure as shown in FIG.

  In the third mode, the control station 5 does not need to transmit a control signal other than the beacon when accepting wireless communication between the device pair. Therefore, it is possible to omit installing the control station 5 in the wireless communication system 1 by providing a function for synchronizing each device. Also in this case, the time during which the device pair performs wireless communication substantially corresponds to the time slot assigned in common to them.

  Next, another embodiment (fourth embodiment) for carrying out the present invention will be described with reference to FIG. In the second aspect, the control station 5 uses a communication request from the device when accepting the wireless communication between the device pair. On the other hand, in the fourth mode, as shown in FIG. 8, while the device pair is performing the directivity control (S20), the control station 5 actively acquires information on these devices ( Step S22). Examples of device information include information on communication partners and directivity information. In this aspect, the control station 5 uses at least directivity information among these pieces of information. For this reason, in this aspect, the device pair does not need to transmit a communication request to the control station 5. This reduces the processing load on each device.

  Then, the control station 5 determines whether or not there is a match between the device pairs based on the acquired device information (for example, directivity information), and when the determination result shows that the match is achieved, The device pair to be communicated is grasped (step S24). When the device information is directivity information, the control station 5 determines whether the directivity of the directional beam is controlled between the device pair to such an extent that wireless communication can be established. , Grasp device pair.

  In the fourth mode, as in the third mode, the control station 5 recognizes the device pair and then accepts the wireless communication of the device pair. However, in order to indicate the acceptance, the control station 5 omits the transmission of the control signal (step S26). Thereby, there can exist an effect equivalent to a 3rd aspect. That is, in this fourth aspect, although the control signal indicating acceptance is not transmitted, the wireless communication performed by the device pair is substantially permitted by the control station 5 (that is, each device is controlled by the control station 5). Below.) Furthermore, the time required for the wireless communication is substantially assigned as a time slot common to both device pairs. For this reason, in this 4th aspect, the processing load of the control station 5 can be reduced significantly.

  In the fourth aspect, transmission of a communication request by each device and transmission of a control signal by the control station 5 are omitted. In the fifth mode instead of this, although the transmission of the communication request by each device is omitted, the transmission of the control signal by the control station 5 is not omitted. In this case, as in the second mode, the control station 5 transmits a control signal including information indicating acceptance to the device pair. Thereby, there can exist an effect equivalent to a 2nd aspect. That is, since the information indicating that the control signal is accepted is included in the control signal, each device can easily determine whether or not to continue wireless communication with other devices.

  Next, another embodiment (sixth embodiment) for carrying out the present invention will be described with reference to FIGS. 9 (a) and 9 (b). In the first mode and the like, the control station 5 assigns a time slot to each device. However, in this mode, the time slot is not explicitly assigned to each device. However, also in this mode, the time slots assigned to the device pairs are the same time slot.

  The radio communication system 1 ′ according to the sixth aspect includes a control station 5 ′ (PNC), a first device 10, and a second device 20 as shown in FIG. 9A. In the wireless communication system 1 ′, wireless communication is performed between the control station 5 ′ and the first device 10, between the control station 5 ′ and the second device 20, and between the first device 10 and the second device 20. A channel is formed, and wireless communication (data communication) is performed via the wireless channel.

  In this case, as shown in FIG. 9B, the control station 5 'assigns a time slot (one time slot) common to all devices included in the wireless communication system 1'. Therefore, the time corresponding to this time slot is longer than the time slot assigned in the above-described manner. For this reason, depending on the device pair and depending on the time, the overlapping state of the directional beams may be bad or may be excellent. Therefore, in the sixth aspect, each device performs data communication with its communication partner only when it is confirmed that the overlapping state of the directional beams is sufficiently high, while the overlapping state of the directional beams is sufficient. If it is not confirmed that the data communication is too high, data communication with the communication partner is omitted or stopped, and data communication with another communication partner is attempted. Thereby, communication efficiency can be maintained.

  Therefore, according to the sixth aspect, data communication is performed when the overlapping state of the directional beams in the device pair is sufficiently high, so that the time slot can be fully utilized. Therefore, communication efficiency is high. On the other hand, when the overlapping state of the directional beams in the device pair is not high, one device tries data communication with another communication partner. For this reason, it is possible to reliably find a communication partner using a long time slot, and the communication efficiency is high. In this aspect, when the device pair attempts data communication, the control station 5 'does not need to grasp the device pair. By using this, when a plurality of devices try to perform wireless communication with respect to one device, wireless communication may be performed intermittently (intermittently) with each device that has attempted the wireless communication. This also makes it possible to utilize a long time slot.

  In the sixth mode as well, the control station 5 ′ may grasp in advance the device pair that attempts data communication. In this case, the control station 5 ′ grasps (recognizes) the device pair that attempts data communication. A time slot is assigned to a device, and a time slot is not assigned to a device that has not been recognized (recognized) as such a device pair. As a result, it is excluded that a device whose directivity of the directional beam is not appropriate attempts data communication. Therefore, communication efficiency can be further improved.

  In the six aspects described above, the control station is separate from the device (wireless terminal), but may be configured integrally. For example, the control station may be built in a certain device. In this case, the device also serves as a control station. Similarly, a device may be built in the control station.

  In each of the six modes described above, each device is configured to transmit a directional beam. Alternatively, the device may be configured to transmit an omnidirectional beam. In this case, the same effect as described above can be obtained. However, when a device pair performs wireless communication using an omnidirectional beam, wireless communication is less likely to be blocked than when a directional beam is used. Therefore, it can be said that the present invention is very effective when a directional beam is used. Furthermore, in wireless communication using a directional beam, it is difficult to properly determine the procedure for controlling the directivity and the procedure for assigning the time slot, in order to obtain the effects described above. According to the first to sixth aspects described above, it becomes easy. Therefore, according to the present invention, it is easy to appropriately set each procedure of the wireless communication method.

  Further, each aspect described above mainly relates to a wireless communication system and a wireless communication method. However, each device constituting the wireless communication system, each process in the wireless communication method, and the superframe structure also constitute the present invention or a part of the present invention. Needless to say, a program (algorithm) corresponding to part or all of the above-described processing and an information storage medium storing the program also constitute the present invention or a part of the present invention.

  The present invention can be used in all fields of wireless communication. The example of wireless communication is not limited to piconet communication. The present invention can also be applied to topologies with a plurality of terminals such as indoor wireless communication networks, computer networks, sensor networks, and the like.

1,1 'wireless communication system 5,5' control station (PNC)
10 first device 20 second device

Claims (11)

A wireless communication method for performing wireless communication using a directional beam between a pair of wireless terminals under the control of the control station in a wireless communication system having at least one control station and a plurality of wireless terminals. There,
When the wireless communication is established between a pair of wireless terminals, a time slot common to both the pair of wireless terminals is allocated under the control of the control station.
Wireless communication method. A time division step in which the control station assigns a time slot necessary for the pair of wireless terminals to perform the wireless communication to be common to both the pair of wireless terminals;
A transmitting step in which the control station transmits, to each of the pair of wireless terminals, a common control signal including information on time slots assigned so as to be common to both of the pair of wireless terminals;
A communication step in which the pair of wireless terminals perform the wireless communication in the time slot allocated in the time division step;
Further including
The wireless communication method according to claim 1. Each of the plurality of wireless terminals further includes a requesting step of transmitting a communication request for performing the wireless communication to the control station,
The time division step includes:
The control station grasps a pair of wireless terminals that should perform the wireless communication in the communication step from the plurality of wireless terminals based on requests transmitted from the plurality of wireless terminals in the request step. Including grasp steps,
The wireless communication method according to claim 2. The communication request is
It is a request for requesting to allocate a time slot common to the wireless terminal that requests the wireless communication.
The wireless communication method according to claim 3. In the time division step,
A time slot necessary for the pair of wireless terminals to perform the wireless communication is assigned to be common to both the pair of wireless terminals, and
Allocation is performed such that a time slot necessary for wireless communication with a wireless terminal pair different from the pair of wireless terminals is common with a time slot required for wireless communication with the pair of wireless terminals. And
The common control signal is:
In the transmission step, the data is transmitted to each of the pair of wireless terminals and the other wireless terminal pair.
The wireless communication method according to claim 2. Each of the plurality of wireless terminals is
It is configured to be able to perform control to adjust the directivity indicating the directivity of the directional beam with a wireless terminal capable of performing the wireless communication,
The wireless communication method is:
A directivity control step for controlling the directivity so that the pair of wireless terminals can perform the wireless communication with each other;
The directivity control step is
Executed after the sending step,
The wireless communication method according to any one of claims 2 to 5. Each of the plurality of wireless terminals is
It is configured to be able to perform control to adjust the directivity indicating the directivity of the directional beam with a wireless terminal capable of performing the wireless communication,
The wireless communication method is:
A directivity control step for controlling the directivity so that the pair of wireless terminals can perform the wireless communication with each other;
The directivity control step is
Executed before the sending step,
The wireless communication method according to any one of claims 2 to 5. The control station
A control signal for controlling the wireless communication is configured to be transmitted to the plurality of wireless terminals;
Each of the plurality of wireless terminals is
It is configured to be able to perform control to adjust the directivity indicating the directivity of the directional beam with a wireless terminal capable of performing the wireless communication,
The wireless communication method is:
A directivity control step for controlling the directivity so that the pair of wireless terminals can perform the wireless communication with each other;
The control station obtaining directivity information related to the directivity control by the pair of wireless terminals in the directivity control step;
A step of determining whether the directivity is matched between the pair of wireless terminals based on the directivity information;
In the determination step, when it is determined that the directivity is matched between the pair of wireless terminals, the control station omits transmission of the control signal,
Thereby, the wireless communication performed by the pair of wireless terminals is substantially permitted by the control station, and the time required for the wireless communication is substantially set as a time slot common to both the pair of wireless terminals. Assigned,
The wireless communication method according to claim 1. Each of the plurality of wireless terminals is
It is configured to be able to perform control to adjust the directivity indicating the directivity of the directional beam with a wireless terminal capable of performing the wireless communication,
The wireless communication method is:
A directivity control step for controlling the directivity so that the pair of wireless terminals can perform the wireless communication with each other;
The control station obtaining directivity information related to the directivity control by the pair of wireless terminals in the directivity control step;
A step of determining whether the directivity is matched between the pair of wireless terminals based on the directivity information;
In the determination step, when it is determined that the directivity is matched between the pair of wireless terminals, the control station performs wireless communication performed by the pair of wireless terminals as information on the time slot. Transmitting the control signal including information indicating that communication is permitted in the transmission step;
Thereby, the time required for the wireless communication is substantially allocated as a time slot common to both of the pair of wireless terminals.
The wireless communication method according to claim 2. The wireless communication is
Piconet communication,
The control station
A coordinator that coordinates the piconet communication by transmitting the control signal as a beacon to the plurality of wireless terminals.
The wireless communication method according to claim 1. A wireless communication system having at least one control station and a plurality of wireless terminals,
When wireless communication is established between a pair of wireless terminals, a time slot common to both of the pair of wireless terminals is allocated under the control of the control station,
The pair of wireless terminals are:
A wireless communication system that performs the wireless communication in the assigned time slot.

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