JP5322006B2 - Time allocation method for radio communication, time allocation device, and radio communication system - Google Patents

Description

  The present invention relates to a time allocation method for radio communication, a time allocation device, and a radio communication system, and relates to a time allocation method and a time allocation device for allocating radio communication time in a radio communication system including a plurality of radio communication devices. And a wireless communication system to which the time allocation method is applied.

  In a wireless communication system, time division is performed to form a segment called a superframe (see Non-Patent Document 1). This super frame is used for time reference for scheduling of frame transmission.

  The super frame has a structure shown in FIG. As shown in FIG. 7, the superframe includes a beacon period (BP), a contention access period (CAP), and a channel time allocation period (CTAP). . In the beacon period (BP), a beacon is transmitted by the network controller (NC). In the contention access period (CAP), CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) type wireless communication is performed. Also, in the channel time allocation period (CTAP), TDMA (time division multiple access) type wireless communication is performed.

  In a wireless communication system, when a pair of a wireless transmitter and a wireless receiver wants to set up a communication link, the wireless transmitter first detects the beacon being transmitted during the beacon period, An association request is sent to the network controller (NC) that sent the beacon. Subsequently, when receiving an association request from the wireless transmitter, the network controller (NC) distributes time slots to the communication link. As a result, a new communication link is established, and the communication link performs wireless communication using the assigned time slot in the CTAP.

  Here, when the number of communication links is large, the network controller (NC) can assign one time slot to each communication link. However, in that case, it is necessary to set the time of each time slot short. In order to avoid this and secure sufficient time slots, the network controller (NC) needs to respond negatively to the association request when the number of communication links exceeds the predetermined number. is there. In that case, as the number of new communication links requiring association increases, the throughput of the wireless communication system decreases significantly.

IEEE, “IEEE 802.15 WPAN Task Group 3c (TG3c) Millimeter Wave Alternative PHY”, [online], April 19, 2009, IEEE, (April 19, 2009 search), Internet, <URL: http://www.ieee802.org/15/pub/TG3c.html>

  Therefore, a main object of the present invention is to provide a time allocation method and a time allocation device that can increase the throughput of a wireless communication system. Another object of the present invention is to provide a radio communication system to which the time allocation method is applied.

  The present invention basically relates to a time allocation method for wireless communication. The time allocation method of the present invention is used in a wireless communication system. In particular, it is preferably used when the wireless communication system includes a wireless communication device including an omni-directional antenna or when wireless communication using a millimeter wave band is performed.

  The object of the present invention described above is achieved by effectively using (reusing) the space between two communication links. Therefore, in the time allocation method of the present invention, an acquisition step, a determination step, and an allocation step are executed. In the acquisition step, information regarding the physical distance between the two communication links is acquired for the communication link. In the determination step, it is determined whether the distance between the two communication links is sufficiently large based on the information regarding the distance. In the assignment step, one time slot is assigned to two communication links that are sufficiently separated from each other. Thereby, two communication links to which one time slot is assigned share one time slot.

  According to the present invention, by effectively using (reusing) the space between two communication links, specifically, the two communication links share one time slot, so that the throughput of the wireless communication system is increased. Can be increased. Even if the throughput of the wireless communication system is increased, the distance between the two communication links is sufficiently large, so that the degree of interference such as CCI can be kept small.

  In another aspect of the present invention, the acquisition step includes a collection step of collecting information related to interference of a plurality of communication links. The determination step includes a determination step of determining two wireless communication devices having the smallest interference with each other from a plurality of wireless communication devices based on the information collected in the collecting step. . Furthermore, the assigning step includes a step of performing scheduling so that one time slot is assigned to the two communication links determined in the determining step. Thereby, interference such as CCI can be surely minimized.

  Furthermore, in a preferred aspect of the invention, the wireless communication system includes a time allocation scheduler. The time allocation scheduler is configured to collect information on interference from all of the plurality of wireless communication devices by transmitting a probing signal to all of the plurality of wireless communication devices in the collecting step. . Thereby, the information regarding interference can be collected more reliably.

  Further, in a further preferred aspect of the present invention, the time allocation scheduler distributes one time slot to two communication links with low mutual interference based on the information collected in the collecting step. Thereby, interference such as CCI can be further minimized.

  In another aspect of the present invention, the wireless communication system is a wireless communication system using a millimeter wave band. Here, when the millimeter wave band is used, the path loss is large. Therefore, the space can be used reliably.

  Furthermore, in another aspect of the present invention, the wireless communication device includes a directional antenna. As described above, even in a wireless communication system including a wireless communication device including an antenna having directivity, according to the present invention, the throughput of wireless communication can be increased.

  Another aspect of the present invention relates to a time allocation device. This time allocation device is a device that allocates time for wireless communication in a wireless communication system including a plurality of wireless communication devices. The time allocation device includes: an acquisition unit configured to acquire information related to a physical distance between two communication links for a communication link including a pair of wireless communication devices among a plurality of wireless communication devices; Determining means for determining whether the distance between the two communication links is sufficiently large based on the information about the distance obtained by the means, and a time division multiple access (TDMA) time slot for each communication link; And assigning means for assigning. If the distance between the two communication links is sufficiently large as a result of the determination in the determination step, the allocating means uses time division multiple access (TDMA) 1 for the two communication links. Means for assigning one time slot. According to such a time allocation device, one time slot can be allocated to two communication links, and one time slot can be shared. Therefore, an effect equivalent to the time allocation method described above can be achieved.

  Still another aspect of the present invention relates to a wireless communication system including a plurality of wireless communication devices. The wireless communication system includes a time allocation device that allocates time for wireless communication. The time allocation device includes an acquisition unit that acquires information about a physical distance between two communication links for a communication link configured by a pair of wireless communication devices among a plurality of wireless communication devices, and an acquisition unit. Judgment means for judging whether the distance between the two communication links is sufficiently large based on the acquired distance information, and allocation for assigning a time division multiple access (TDMA) time slot to each communication link Means. If the distance between the two communication links is sufficiently large as a result of the determination in the determination step, the allocating means uses time division multiple access (TDMA) 1 for the two communication links. Means for assigning one time slot. According to such a wireless communication system, one time slot is allocated to two communication links, and one time slot is shared. Therefore, an effect equivalent to the time allocation method described above can be achieved.

  ADVANTAGE OF THE INVENTION According to this invention, the throughput of a communication link radio | wireless communications system can be raised by using effectively the space between two communication links (reuse). Further, even if the throughput of the wireless communication system is increased, interference such as CCI can be minimized.

FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to the present invention. FIG. 2 is a flowchart showing the procedure of the time slot allocation method executed by the network controller (NC) in FIG. FIG. 3 is a schematic view for explaining the structure of the super frame according to the present invention. FIG. 4 is a diagram for explaining the relationship between the time slots assigned in accordance with the processing shown in FIG. 2 and the communication links 1 to 4. FIG. 5 is a diagram for explaining the relationship between assigned time slots and communication links 1 to 4 in another aspect of the present invention. FIG. 6 is a diagram for explaining the relationship between the time slots assigned by the prior art and the communication links 1 to 4. FIG. 7 is a schematic diagram for explaining the structure of a conventional superframe.

  Hereinafter, the best mode 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 of a wireless communication system according to the present invention.

  A wireless communication system 1 shown in FIG. 1 includes an NC-equipped device and a plurality of wireless communication devices. In the wireless communication system 1, wireless communication (data communication) using a millimeter wave band (for example, 60 GHz band) is performed between a plurality of wireless communication devices. Data communication is performed between one pair of wireless communication devices using one of the available channels.

  The wireless communication device is configured to be able to transmit / receive data to / from other wireless communication devices. Accordingly, during wireless communication, one wireless communication device functions as a wireless transmitter that transmits data, and the other wireless communication device functions as a wireless receiver that receives transmitted data. Note that the wireless communication device may be capable of only transmitting data or only capable of receiving data. In this case, at least between the device and the NC-equipped device. It is configured to be able to perform association.

  The NC-equipped device is equipped with a network controller (NC), and is configured to be able to transmit and receive data in the same manner as a wireless communication device. An example of a network controller (NC) is a piconet coordinator (PNC).

  The network controller (NC) performs access control for a plurality of wireless communication devices belonging to the wireless communication device 1. The network controller (NC) is configured to determine a pair of wireless communication devices (hereinafter also referred to as a communication link) to establish wireless communication after performing access control. In the example shown in FIG. 1, since the number of wireless communication devices is 8, four communication links (communication links 1, 2, 3, 4) are formed. Therefore, the network controller (NC) is surrounded by four communication links.

  The network controller (NC) is provided with a time allocation scheduler (not shown). This time allocation scheduler may be formed by software, or a part thereof may be configured by hardware. The time allocation scheduler is for allocating time slots to communication links determined by the network controller (NC). The time slot is a time for wireless communication in the wireless communication system 1 and corresponds to a time required for establishing a wireless communication for the communication link.

  By the way, in the wireless communication system 1 according to this aspect, at least one of the plurality of channels can be used. Therefore, the time allocation scheduler is configured to allocate a time slot capable of wireless communication using one available channel to each communication link. Here, the number of time slots that can be assigned to one channel is set in advance so as to be sufficient for wireless communication in CTAP, for example, three. Therefore, the time allocation scheduler is configured to allocate a plurality of communication links to one time slot when the number of communication links is larger than the number of available time slots. As a result, in the wireless communication system 1, a plurality of communication links can share one time slot and perform wireless communication. That is, TDMA type wireless communication can be performed. As a result, the throughput of the wireless communication system 1 can be increased.

  By the way, when the time allocation scheduler allocates a plurality of communication links to one time slot, a plurality of wireless transmitters transmit data at the same timing using one channel. As a result, interference occurs in the channel. Such interference is called common channel interference (CCI: co-channel interference). If there is such interference, the performance of the wireless communication system 1 will be significantly reduced. Therefore, in this aspect, in consideration of CCI (specifically, to minimize CCI), a plurality of communication links are assigned to time slots. This allocation method will be described with reference to FIG.

  FIG. 2 is a flowchart showing the procedure of the time slot allocation method executed by the network controller (NC) in FIG. The process of FIG. 2 is executed in the CTAP of the super frame. Therefore, the association has already been completed in the CAP before the processing of FIG. 2 is executed. In this aspect, in the wireless communication system 1 shown in FIG. 1, one channel is usable, the number N of usable time slots is three, and the number L of communication links is four. Will be described as an example. Further, in this aspect, a case where the transmission output of each communication link is the same as the transmission output of other communication links will be described as an example.

  In FIG. 2, first, in step S10, the time allocation scheduler of the network controller (NC) performs monitoring in the probing signal transmission period (PSBP) after the association is completed in the CAP. The object of monitoring is the instantaneous value of any interference that can occur in the wireless communication system. This monitoring is preferably performed periodically.

  In order to realize this monitoring, all communication links are obliged to periodically send probing signals within the superframe CTAP. For this purpose, a probing signal transmission period (PSBP: probing signal broadcasting period) is set in the CTAP of the superframe as shown in FIG. In the probing signal transmission period (PSBP), each wireless communication device (particularly a wireless transmitter) transmits a probing signal. In this embodiment, the network controller (NC) also receives (collects) the probing signal. As a result, the network controller (NC) collects information from all wireless communication devices.

  Subsequently, the time allocation scheduler uses the information included in the probing signal collected from the wireless transmitter to obtain information on the transmission output when transmitting a signal such as a probing signal, and other information coexisting in the wireless communication system 1. Information on the degree of CCI that can be given to the communication link is acquired. As information on the degree of CCI, in this embodiment, information on a distance from a communication link including a wireless transmitter that transmits a probing signal to another communication link is used. Here, as the distance between the communication links is longer, the interference such as CCI is reduced due to the path loss due to the free space between them. Therefore, it can be said that the information regarding distance is an example of information regarding the degree of CCI. Note that the above path loss becomes significant in the millimeter wave band. That is, when the wireless communication system 1 is a wireless communication system using the millimeter wave band, the degree of CCI can be reduced as the distance between communication links increases. In this embodiment, this property is used.

  Here, in the example shown in FIG. 1, the distance-related information includes the distance a between the communication link 1 and the communication link 4, the distance b between the communication link 2 and the communication link 4, and the distance between the communication link 3 and the communication link 4. corresponding to c. As shown in FIG. 1, the relationship between the distance a, the distance b, and the distance c is such that a is the largest and c is the smallest (a> b> c). That is, the communication links 1 to 3 are close to each other, and the communication link 4 is away from the communication links 1 to 3, and is most distant from the communication link 1.

Then, the time allocation scheduler creates a signal strength table based on the information acquired from the probing signal. In the signal strength table, CCI from each communication link to other communication links is recorded as an interference value, and the interference value is recorded over all combinations of communication links. In this aspect, since the signal strength value (information regarding the transmission output) of the communication link is the same, the interference value is reduced according to the distance (for example, in proportion to the distance). Therefore, the network controller (NC) first refers to this signal strength table in order to assign the available three time slots to a plurality of communication links, so that the CCI for each other can be selected from among the plurality of communication links. Two communication links having a small interference value (that is, two farthest communication links) are determined.

  In subsequent step S20, the network controller (NC) selects one communication link (for example, communication link 1) from the plurality of communication links. Here, the selected communication link is a communication link other than the two communication links having a small CCI interference value among the plurality of communication links. In the example shown in FIG. 1, since the communication link 1 and the communication link 4 are farthest away, one of the communication link 2 and the communication link 3 (for example, the communication link 3) is selected. Then, for example, an arbitrary time slot or a predetermined time slot among a plurality of available time slots is assigned to the channel selected in this way (scheduling).

  In subsequent step S30, the network controller (NC) determines whether or not the number of communication links is greater than the number of available time slots. In this aspect, since the number of communication links is one more than the number of available time slots, it is determined that the number is larger.

  If the number of communication links is greater than the number of time slots (YES in step S30), the network controller (NC) selects the communication link (other communication link) having the largest CCI with respect to the selected communication link. (Step S40). Also in this case, a communication link other than the two communication links having a small CCI interference value is selected from the plurality of communication links. Here, the communication link having the largest CCI selected in step S20 is selected by referring to (evaluating) the signal strength table.

  In step S50, it is determined whether there is a time slot (empty slot) to which no communication link is assigned. If there is an empty slot (YES in step S50), a time slot different from the time slot assigned to the communication link selected in step S20 is assigned to the communication link selected in step S40 (step S60). ). As a result, two communication links close to each other (that is, two communication links having high interference with each other) do not share one time slot. In the example shown in FIG. 1, when the communication link 3 is selected, the communication link 2 having the largest interference value is selected. This coincides with the fact that the communication links 1, 2, and 3 are close to each other and the communication link 4 is separated as shown in FIG.

  Subsequently, in step S70, it is determined whether or not there is a communication link (other communication link) to which no time slot is assigned. If there is a communication link to which no time slot is assigned as a result of this determination (YES in step S70), the process returns to step S20 to assign a time slot to these communication links. If no time slot is assigned to only the two communication links with the smallest interference, one communication link is selected in step S20.

  On the other hand, if the result of determination in step S70 is that there is no communication link to which a time slot should be assigned, this process (time slot assignment process) is terminated. If it is determined in step S30 that the number of communication links is the same as or smaller than the number of time slots, the process proceeds to step S70. Thereby, it returns to step S20 and a time slot can be allocated with respect to another communication link. In this case, one time slot is assigned to each communication link as in the conventional TDMA type wireless communication system.

As a result of the determination in step S50, if there is no empty slot, that is, when assigning the one communication link for all time slots, the communication link selected in step S 10, the time slot sharing Setting is performed (step S80). In the example shown in FIG. 1, the communication link 4 is set (scheduled) so as to share the time slot assigned to the communication link 1. Thereafter, the process of step S70 is performed. If there is no communication link to which a time slot should be assigned, this process (time slot assignment process) is terminated.

  FIG. 4 shows the relationship between the time slots assigned according to the time slot assignment process and the communication links 1 to 4. As can be seen from FIG. 4, first, the communication link 3 is assigned to the time slot 1. Second, the communication link 2 is assigned to the time slot 2. Third, the communication link 1 is assigned to the time slot 3. Furthermore, the time slot 3 is assigned so that the communication link 4 having the smallest CCI for the communication link 1 is shared. These assignments were made in response to communication links 1 to 3 being close to each other, communication link 4 being remote from communication links 1 to 3 and being most remote from communication link 1. Is.

  As described above in detail, according to the above-described aspect, first, when two communication links are allocated so as to share a time slot, when the interference value of CCI with respect to each other becomes large, it differs. A time slot is assigned. Second, when there are more communication links than available time slots, the time slots are allocated so that the two communication links share the time slots. Thirdly, as two communication links sharing a time slot, two communication links having a smaller CCI interference value are selected from among a plurality of communication links. Note that three or more communication links may share time slots. In this way, when a plurality of (two or three or more) communication links share one time slot, the total CCI generated by the communication links is set so as not to exceed a preset threshold.

  Thus, according to the above aspect, the network controller (NC) can allocate time slots to a large number of communication links. As a result, the throughput of the wireless communication system 1 is increased. Further, two (or more) communication links sharing a time slot have a small CCI interference value with respect to each other, so that the performance of the wireless communication system 1 can be prevented from deteriorating. That is, according to this aspect, it is possible to realize both an increase in throughput of the wireless communication system 1 and a reduction in CCI. Note that according to this aspect, path loss in free space is used in order to share a time slot among a plurality of communication links. This can be said to be using (reusing) space. On the other hand, in the conventional technology that does not consider the use (reuse) of such a space, as shown in FIG. 6, for a communication link (eg, communication link 4) exceeding the number of timeslots (eg, 3). Cannot be assigned. Therefore, in the prior art, the communication link 4 needs to wait at least for the arrival of the next super frame, resulting in a reduction in throughput.

In the process of FIG. 2, with respect to interference is the largest two communication links, previously assigned time slots (unshared timeslot), subsequently, the time slot to interference is the smallest two communication links (Shared time slot) is assigned. Another alternative is to assign an arbitrary number of time slots to the same number of communication links as the number of time slots, and then to other communication links that exceed the number of time slots. A time slot may be assigned to be shared with the communication link. As a specific example, time slots are assigned to the communication links 1, 2, and 3, and the time slot assigned to the communication link 1 with the smallest interference is assigned to the communication link 4 (see FIG. 5). The effect equivalent to the said aspect can be show | played also by such another aspect. In this alternative embodiment, instead of creating a signal strength table for all communication links, a signal strength table may be created only for communication links exceeding the number of time slots and related communication links. . As a result, the processing load can be reduced.

  In addition, it is not restricted to the aspect mentioned above and another aspect, What is necessary is just to be able to allocate a time slot so that two communication links with the smallest interference share a time slot.

  In the above aspect and the above another aspect, the signal strength of the probing signal is the same. However, the signal strength of the probing signal may be different. In this case, the network controller (NC) obtains information regarding interference from information regarding the signal strength of the probing signal and information regarding the distance between the communication links. Specifically, the network controller (NC) first calculates the ratio of the signal strength of the probing signal to the reference value, and then changes the distance between communication links according to the ratio of the signal strength. The value is recorded in the signal strength table as information on interference. The reason why information about interference is obtained in this way is that the signal strength and the interference occurring in the signal are alleviated according to the distance.

  Moreover, in the said aspect and said another aspect, since a path | route loss is utilized, it is effective especially when a communication link is a radio | wireless communications system using a millimeter wave band. Furthermore, in the above aspect and the above-mentioned another aspect, path loss is used. Therefore, it is particularly effective when the wireless communication device constituting the wireless communication system includes a directional antenna (for example, an omni directional antenna). It is. Since such an antenna has a high directivity, it is easy to estimate the degree of CCI. Therefore, accurate information can be recorded by the signal strength table, and as a result, a plurality of communication links that should share one time slot can be accurately determined. Further, when the antenna of the wireless communication device has directivity and the wireless communication device moves, it is usually difficult to assign a time slot. However, according to the above aspect and the other aspect, it is possible to assign a time slot to a communication link including such a wireless communication device, and it is possible to reliably increase the throughput of the wireless communication system.

In the above aspect or the above other aspect, the communication link to which the time slot is initially assigned is the communication link 3 or the communication link 1, but is the communication link (communication link 4) having the smallest interference value in the signal strength table. There may be. In this case, a shared time slot is determined first, and a non-shared time slot is allocated later.

Moreover, in the said aspect and said another aspect, although the communication link was allocated in an order from the time slot 1 among the three available time slots 1-3, you may allocate a communication link from another time slot. In this case, it is preferable that a priority order for allocation is determined in advance for each time slot.

  Moreover, in the said aspect or said another aspect, it is preferable to perform monitoring in multiple times. Thereby, the signal strength table can be periodically updated. More preferably, channel distribution processing is performed each time the interference monitoring table is updated. As a result, even if the wireless communication device moves, channel distribution processing can be performed using the latest interference value. The monitoring is preferably performed every time a super frame arrives, but may be performed every time a time corresponding to a plurality of super frames elapses.

  In the above and other aspects, the shared channel setting is performed when the number of channels is smaller than the number of communication links. However, when the traffic is not congested, the shared channel setting is not performed. In addition, it is possible to wait until the traffic is alleviated, or to set adjacent channels in steps S70 to S80. In this case, the network controller (NC) determines whether the traffic is congested.

  Moreover, the said aspect and said another aspect were mainly related with the radio | wireless communications system 1 and the radio | wireless communication method (time slot allocation method). However, the format and frame structure of data including the fields described in the above aspects also constitute the present invention or a part of the present invention. Further, a wireless communication device and a network controller (NC) constituting the wireless communication system 1 described above, a program (algorithm) corresponding to a part or all of the processing described above, and an information storage medium storing the program, It goes without saying that the present invention or a part of the present invention is constituted.

  The present invention can be suitably used in the field of wireless communication. In particular, the present invention can be applied to a network controller (NC) or a wireless communication device (wireless receiver or wireless transmitter) of a wireless communication system. As a wireless communication system, for example, there is a WPAN system (wireless personal area network) using a millimeter wave band.

1 Wireless communication system NC Network controller

Claims (5)

A time allocation method for allocating time for wireless communication in a wireless communication system including a plurality of wireless communication devices and a time allocation scheduler ,
The time allocation scheduler is
By transmitting a probing signal from all of the plurality of wireless communication devices, among the plurality of wireless communication devices, information on interference of a plurality of communication links configured with a pair of wireless communication devices is collected and each communication is performed. A collection step for creating a signal strength table in which interference values from the link to other communication links are recorded ;
A determination step of referring to the signal strength table to determine two communication links having the smallest interference with each other (hereinafter referred to as “two minimum interference communication links”) from among the plurality of communication links; ,
When one communication link (hereinafter referred to as “reference communication link”) other than the two minimum interference communication links is selected from the plurality of communication links, a plurality of times when the reference communication link can be used. A first allocation step of allocating one time slot among division multiple access (TDMA) time slots;
A slot number determination step for determining whether the number of the plurality of communication links is greater than the number of available time division multiple access (TDMA) timeslots;
Communication having the largest interference with respect to the reference communication link among the communication links other than the two interference minimum communication links when it is determined in the determination step that the number of communication links is larger than the number of time slots. A second allocation step of selecting a link (hereinafter referred to as a “reference maximum interference communication link”) and allocating a time slot different from the reference communication link to the reference maximum interference communication link;
Repeated,
Shared allocation step of allocating one time slot to the two minimum interference communication links when the communication link to which the time throttle is not allocated is only the two minimum interference communication links among the plurality of communication links. By doing
The two interference minimum communication links to which the one time slot is assigned share one time slot;
Time allocation method. The wireless communication system is a wireless communication system using a millimeter wave band.
The time allocation method according to claim 1 . The wireless communication device includes a directional antenna;
The time allocation method according to claim 1 or 2 . In a wireless communication system including a plurality of wireless communication devices, a time allocation device for allocating time for wireless communication,
The time allocation device is :
By transmitting a probing signal from all of the plurality of wireless communication devices, among the plurality of wireless communication devices, information on interference of a plurality of communication links configured with a pair of wireless communication devices is collected and each communication is performed. A collection step for creating a signal strength table in which interference values from the link to other communication links are recorded ;
A determination step of referring to the signal strength table to determine two communication links having the smallest interference with each other (hereinafter referred to as “two minimum interference communication links”) from among the plurality of communication links; ,
When one communication link (hereinafter referred to as “reference communication link”) other than the two minimum interference communication links is selected from the plurality of communication links, a plurality of times when the reference communication link can be used. A first allocation step of allocating one time slot among division multiple access (TDMA) time slots;
A slot number determination step for determining whether the number of the plurality of communication links is greater than the number of available time division multiple access (TDMA) timeslots;
Communication having the largest interference with respect to the reference communication link among the communication links other than the two interference minimum communication links when it is determined in the determination step that the number of communication links is larger than the number of time slots. A second allocation step of selecting a link (hereinafter referred to as a “reference maximum interference communication link”) and allocating a time slot different from the reference communication link to the reference maximum interference communication link;
Repeated,
A shared assignment step of assigning the one time slot to the two communication links when the communication link to which the time throttle is not assigned is only the two interference minimum communication links among the plurality of communication links; By doing
The two interference minimum communication links to which the one time slot is assigned share one time slot;
Time allocation device. A wireless communication system including a plurality of wireless communication devices,
Including a time allocation device for allocating time for wireless communication;
The time allocation device is:
By transmitting a probing signal from all of the plurality of wireless communication devices, among the plurality of wireless communication devices, information on interference of a plurality of communication links configured with a pair of wireless communication devices is collected and each communication is performed. A collection step for creating a signal strength table in which interference values from the link to other communication links are recorded ;
A determination step of referring to the signal strength table to determine two communication links having the smallest interference with each other (hereinafter referred to as “two minimum interference communication links”) from among the plurality of communication links; ,
When one communication link (hereinafter referred to as “reference communication link”) other than the two minimum interference communication links is selected from the plurality of communication links, a plurality of times when the reference communication link can be used. A first allocation step of allocating one time slot among division multiple access (TDMA) time slots;
A slot number determination step for determining whether the number of the plurality of communication links is greater than the number of available time division multiple access (TDMA) timeslots;
Communication having the largest interference with respect to the reference communication link among the communication links other than the two interference minimum communication links when it is determined in the determination step that the number of communication links is larger than the number of time slots. A second allocation step of selecting a link (hereinafter referred to as a “reference maximum interference communication link”) and allocating a time slot different from the reference communication link to the reference maximum interference communication link;
Repeated,
A shared assignment step of assigning the one time slot to the two communication links when the communication link to which the time throttle is not assigned is only the two interference minimum communication links among the plurality of communication links; By doing
The two interference minimum communication links to which the one time slot is assigned share one time slot;
Wireless communication system.

Images