Wireless communication monitoring method, wireless communication monitoring system, and wireless communication monitoring device

Abstract

The present invention manages wireless communication in a network that has a first link for wireless communication between a first station (first STA) functioning as a repeater and a first access point (first AP) functioning as a parent unit, and has a second link for wireless communication between a second station (second STA) functioning as a child unit and the first STA. The present invention sets, on the basis of a first transmission amount to be communicated using the first link, a first transmission time at which the first link is permitted to carry out transmission. The present invention sets, on the basis of a second transmission amount to be communicated using the second link, a second transmission time at which the second link is permitted to carry out transmission. The present invention derives a whole transmission cycle on the basis of the first and second transmission times, and derives first and second transmission periods so as not to overlap each other in the whole transmission cycle. The present invention controls wireless apparatuses in the network such that the wireless communication to be carried out using the first link is limited to the first transmission period and the wireless communication to be carried out using the second link is limited to the second transmission period.

Description

Technical Field

[0001] This disclosure relates to a wireless communication monitoring method, a wireless communication monitoring system, and a wireless communication monitoring device, and particularly relates to a wireless communication monitoring method, a wireless communication monitoring system, and a wireless communication monitoring device that are suitable for improving the efficiency of communication via a relay device.

Background Art

[0002] As a configuration of wireless communication, a configuration in which a relay device is interposed between a parent device AP (Access Point) and a child device STA (Station) of wireless communication is known. In such a configuration, data communication is performed on both a wireless path between the parent device AP and the relay device (hereinafter referred to as "first link") and a wireless path between the relay device and the child device STA (hereinafter referred to as "second link"). Therefore, it is necessary to avoid interference between the first link and the second link.

[0003] Non-Patent Document 1 below discloses a CSMA / CA (Carrier-Sense Multiple Access with Collision Avoidance) method as a technique for avoiding interference between a plurality of wireless communication devices arranged adjacent to each other. In the CSMA / CA method, a device that desires to transmit data transmits a data frame when it performs carrier sense and determines that there is no interference wave around. According to this method, a device that detects a wireless signal transmitted from another device stops wireless transmission. Therefore, each device can avoid a collision with the detected wireless signal and transmit its own wireless signal.

[0004] In addition, as a wireless communication standard, there is known one that imposes a restriction on the transmission time of each device. For example, Non-Patent Document 2 below discloses a technique for imposing a restriction on each device that the transmission time per hour (3600 seconds) is 360 seconds (10% of one hour) regarding the use of the 920 MHz band. According to such a technique, it is possible to suppress the occurrence of an imbalance in communication volume as a whole by unevenly allocating the transmission time only to some devices.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a configuration where a relay device is interposed between the parent device AP and the child device STA, a situation may occur where a wireless signal emitted from the parent device AP reaches the relay device but does not reach the child device STA. Similarly, a situation may occur where a wireless signal emitted from the child device STA reaches the relay device but does not reach the parent device AP.

[0007] In such an environment, even if a wireless signal is emitted from the parent device AP towards the relay device, the child device STA cannot detect the signal. Also, even if a wireless signal is emitted from the child device STA towards the relay device, the parent device AP cannot detect the signal.

[0008] As a result, the so-called hidden terminal problem occurs, and around the relay device, a collision occurs between the wireless signal from the parent device AP and the wireless signal from the child device STA. For this reason, when using a configuration in which a relay device is interposed between the parent device AP and the child device STA, in the conventional CSMA / CA method, a situation where the transmission time cannot be efficiently utilized easily occurs.

[0009] Also, in a configuration using a relay device, if the amount of data provided from the child device STA to the relay device becomes larger than the amount of data sent from the relay device to the parent device AP, packet loss occurs in the relay device. For example, when the relay device is placed in an environment where it is difficult to obtain access rights to the parent device AP, if data from the child device STA is continuously uploaded to the relay device, packet loss occurs after the data accumulation amount of the relay device reaches the upper limit. Also, under rules where a transmission time limit is imposed on each device, after the transmission time of the relay device reaches the upper limit, a state will continue where data is continuously provided from the child device STA to the relay device, and again packet loss occurs. Also in this case, the efficiency of wireless communication deteriorates as a whole.

[0010] The present disclosure has been made in view of the above problems, and a first object is to provide a wireless communication monitoring method capable of continuing efficient wireless communication in a wireless communication configuration using a relay device.

[0011] Also, a second object of the present disclosure is to provide a wireless communication monitoring system capable of continuing efficient wireless communication in a wireless communication configuration using a relay device.

[0012] Also, a third object of the present disclosure is to provide a wireless communication monitoring device capable of continuing efficient wireless communication in a wireless communication configuration using a relay device.

Means for Solving the Problems

[0013] A first aspect is a wireless communication monitoring method for managing wireless communication in a network having a first link for wireless communication between a relay device and a master device and a second link for wireless communication between the relay device and a slave device, in order to achieve the above object, setting a first transmission time for permitting transmission on the first link based on a first transmission amount to be communicated on the first link; setting a second transmission time for permitting transmission on the second link based on a second transmission amount to be communicated on the second link; determining an overall transmission cycle based on the first transmission time and the second transmission time, and within the overall transmission cycle, determining a first transmission period corresponding to the first transmission time and a second transmission period corresponding to the second transmission time so as not to overlap with each other; controlling wireless devices included in the network such that wireless transmission to be performed on the first link is restricted to the first transmission period and wireless communication to be performed on the second link is restricted to the second transmission period; and desirably includes.

[0014] A second aspect is a wireless communication monitoring system including a network having a first link for wireless communication between a relay device and a master device and a second link for wireless communication between the relay device and a slave device, by at least one or both of the relay device and the master device, a process of setting a first transmission time for permitting transmission on the first link based on a first transmission amount to be communicated on the first link; a process of setting a second transmission time for permitting transmission on the second link based on a second transmission amount to be communicated on the second link; a process of determining an overall transmission cycle based on the first transmission time and the second transmission time, and within the overall transmission cycle, determining a first transmission period corresponding to the first transmission time and a second transmission period corresponding to the second transmission time so as not to overlap with each other; processing for controlling wireless devices included in the network so that wireless transmission to be performed on the first link is restricted to the first transmission period and wireless communication to be performed on the second link is restricted to the second transmission period is preferably configured to be executed.

[0015] A third aspect is a wireless communication monitoring apparatus for managing wireless communication in a network having a first link for wireless communication between a relay device and a master device and a second link for wireless communication between the relay device and a slave device, processing for setting a first transmission time for permitting transmission on the first link based on a first transmission amount to be communicated on the first link; processing for setting a second transmission time for permitting transmission on the second link based on a second transmission amount to be communicated on the second link; processing for determining an overall transmission cycle based on the first transmission time and the second transmission time, and determining a first transmission period corresponding to the first transmission time and a second transmission period corresponding to the second transmission time so as not to overlap with each other within the overall transmission cycle; processing for controlling wireless devices included in the network so that wireless transmission to be performed on the first link is restricted to the first transmission period and wireless communication to be performed on the second link is restricted to the second transmission period; is preferably configured to execute.

Advantages of the Invention

[0016] According to the first to third aspects, in a configuration of wireless communication using a relay device, by preventing frame collisions and preventing the occurrence of packet loss, efficient wireless communication can be continued.

Brief Description of the Drawings

[0017]

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Embodiments for Carrying Out the Invention

[0018] Embodiment 1. [Configuration of Embodiment 1] FIG. 1 shows an example of a network including the wireless communication monitoring system according to Embodiment 1 of the present disclosure. The system shown in FIG. 1 includes a first master device (first AP) 10. The first AP 10 functions as a route AP that communicates with a higher-level communication system via a communication path (not shown).

[0019] A first slave device (first STA) and relay device 12 is communicably connected to the first AP 10 via a wireless section. The first slave device and relay device 12 is equipped with the function of a slave device for enabling wireless communication with the first AP 10 and the function of a relay device. Hereinafter, the first slave device and relay device 12 is referred to as "first STA 12" for convenience.

[0020] A second master device (second AP) 14 is connected to the first STA 12. The first STA 12 and the second AP 14 may be physically separate devices. In this case, the two are assumed to be connected by wire. Also, the first STA 12 and the second AP 14 may be an integrated device. In this case, the two are assumed to be connected by an internal connection. The first STA 12 can relay data sent from the first AP 10 toward the second AP 14 and can also relay data sent from the second AP 14 toward the first AP 10.

[0021] A second slave device (second STA) 16 is communicably connected to the second AP 14 via a wireless section. That is, in the wireless communication monitoring system shown in FIG. 1, wireless links are respectively formed between the first AP 10 and the first STA 12 and between the second AP 14 and the second STA 16. Hereinafter, the former is referred to as "first link 18" and the latter is referred to as "second link 20".

[0022] FIG. 2 shows a block diagram for explaining the configuration of the first AP 10. As shown in FIG. 2, the first AP 10 includes a control unit 22. The control unit 22 includes an arithmetic processing unit and a memory (not shown). The function of the control unit 22 is realized by the arithmetic processing unit executing processing according to a program stored in the memory.

[0023] The first AP 10 also includes a transmission unit 24 and a reception unit 26. The transmission unit 24 and the reception unit 26 send and receive data frames according to commands from the control unit 22. The transmission unit 24 has functions for enabling wired transmission 28 and wireless transmission 30. Similarly, the reception unit 26 has functions for enabling wired reception 32 and wireless reception 34. In this embodiment, among them, the wireless transmission 30 and reception 34 are performed via the first link 18.

[0024] Both the first STA 12 and the second AP 14 have the same hardware configuration as the first AP 10 shown in FIG. 2. The first STA 12 realizes communication for relaying through a function of transmission and reception via wire (corresponding to 28 and 32), and realizes communication with the first AP 10 through a function of transmission and reception via wireless (corresponding to 30 and 34). Also, the second AP 14 realizes communication for relaying through a function of transmission and reception via wire (corresponding to 28 and 32), and realizes communication with the second STA 16 through a function of transmission and reception via wireless (corresponding to 30 and 34).

[0025] FIG. 3 shows a block diagram for explaining the configuration of the second STA 16. The second STA 16 includes a control unit 36, a transmission unit 38, and a reception unit 40. These have substantially the same functions as the elements shown in FIG. 2, except that the transmission unit 38 and the reception unit 40 only have functions of wireless transmission 42 and reception 44. The second STA 16 realizes communication via the second link 20 through those functions of wireless transmission 42 and reception 44.

[0026] [Problems of Embodiment 1] FIG. 4 is a diagram for explaining problems that occur when the CSMA / CA method is applied to the network shown in FIG. 1. In the CSMA / CA method, a device that desires to send data wirelessly performs carrier sense, that is, confirms that no wireless signal is being emitted from other devices, and sends a data frame when such confirmation is obtained.

[0027] In the network shown in FIG. 1, it is assumed that the first STA 12 and the second AP 14 are arranged at substantially the same position or in the same housing. On the other hand, since it is sufficient for the first AP 10 to be able to communicate with the first STA 12 via the first link 18, there may be a situation where the radio signal emitted by the first AP 10 is not detected by the second STA 16. Similarly, there may also be a situation where the radio signal emitted by the second STA 16 is not detected by the first AP 10. Thus, in the network shown in FIG. 1, the first AP 10 and the second STA 16 may each become a "hidden terminal" that is not visible to the other party.

[0028] In FIG. 4, a series of events starting at time t1 shows a state where data frame collisions occurred after time t2 because the first AP 10 and the second STA 16 are hidden terminals. Also, a series of events starting at time t3 shows a state where the second AP 14 is affected by frame collisions because the first STA 12 and the second STA 16 simultaneously started uploading data frames. Furthermore, a series of events starting at time t4 shows a state where both the receiving first AP 10 and the second STA 16 are affected by data collisions because the first STA 12 and the second AP 14 started transmitting data frames simultaneously.

[0029] In the CSMA / CA method, regardless of each other's transmission states, each terminal accesses the channel based on the result of carrier sense. Therefore, frame collisions as described above can occur. Even if the first STA 12 and the second AP 14 responsible for relaying divide the channel, if the channels are adjacent, the frame error rate will become extremely high due to each other's leakage power. For this reason, in the network assumed in this embodiment, it is difficult to achieve efficient communication by the CSMA / CA method.

[0030] FIG. 5 illustrates a state where packet loss occurs due to an imbalance in data transmission volume. In the network configuration of the present embodiment, the first STA 12 may be placed in an environment where it is difficult to acquire access rights to the first AP 10. Further, this network is also assumed to be used in an environment where transmission time constraints are imposed on individual terminals, such as in the 920 MHz band in Japan.

[0031] In the example shown in FIG. 5, at time t1, data is being uploaded from the second STA 16 to the second AP 14. Further, the data uploaded to the second AP 14 is provided to the first STA 12 through a wired or internal connection path. Since the data transfer is successful, an Ack signal is generated at the second AP 14. Then, the second STA 16 recognizes the success of data transmission by the Ack signal and subsequently requests data uploads at times t3, t4, and t5 in the same manner.

[0032] On the other hand, at time t2, the first STA 12 acquires access rights to the first AP 10 and transfers the received data, but thereafter, the transfer of the received data is not successful. Such a situation can occur sufficiently when the first STA 12 is placed in an environment where it is difficult to acquire access rights to the first AP 10. Also, taking the 920 MHz band in Japan as an example, the time during which an individual terminal can transmit data is limited to 360 seconds per hour (3600 seconds). And if the first STA 12 uses up the 360 seconds of time for the transmission at time t2, then from time t3 onwards, data will be provided to the first STA 12 on the one hand. Since the packet accumulation capacity of the first STA 12 is limited, if the situation shown in FIG. 5 continues, packet loss will occur where the packets sent from the second STA 16 disappear without reaching the first AP 10.

[0033] [Features of Embodiment 1] FIG. 6 is a timing chart for explaining the outline of the communication rules adopted in the present embodiment to solve the above problems. In the technology of the present embodiment, the allocation of the transmission period is determined for each of the first link 18 between the first AP 10 and the first STA 12 and the second link 20 between the second AP 14 and the second STA 16. Then, the transmission on each of the first link 18 and the second link 20 is permitted only during the determined transmission period.

[0034] FIG. 6 shows an example in which the time periods t1 to t2 and t3 to t4 are determined as the transmission periods of the first link 18, and the time period t2 to t3 is set as the transmission period of the second link 20. Each transmission period is determined based on the number of packets that can tolerate reception, communication quality, etc. Also, when there is a limit on the transmission time, each device performs transmission within a range not exceeding the transmission time limit during each transmission period.

[0035] In the present embodiment, the transmission period of each link is determined by the first STA 12 having a relay function. Then, the actual transmission restriction is performed using the TWT (Target Wake Time) method, the RAW (Restricted Access Window) method, or the like. In addition, a function of temporarily stopping the transmission from the module, such as the sleep mode, may be used to suppress the transmission outside the transmission period. However, beacon frames and the like may be permitted to be transmitted outside the transmission period for synchronization and connection of new terminals, except when the law cannot be observed if a plurality of terminals transmit simultaneously.

[0036] The network of the present embodiment can be used for IoT (Internet of Things) applications. For example, the first STA 12 and the second STA 16 can be mounted on electrical appliances or the like and upload data representing the state of the device to the first AP 10 and the second AP 14, respectively. Also, the first STA 12 and the second STA 16 can download data for update from the first AP 10 and the second AP 14, respectively.

[0037] In the network of this embodiment, the data uploaded from the second STA 16 to the second AP 14 is relayed by the first STA 12 and transmitted to the first AP 10 via the first link 18. Also, the data downloaded by the second STA 16 is provided from the first AP 10 via the relay of the first STA 12. That is, the second link 20 transmits only the data exchanged by the second STA 16, while the first link 18 transmits the data for two devices, namely the first STA 12 and the second STA 16. Therefore, it is desirable to use as high a transmission rate as possible for the first link 18.

[0038] In particular, in an environment where there is a limit on the transmission time, such as the 920 MHz band in Japan, it is more advantageous for capacity expansion to be able to transmit a large number of packets within the same time. For this reason, for the first link 18, it is desirable to use, for example, a wide bandwidth (4 MHz band in the case of IEEE. 11ah). Also, for the second link, it is desirable to use a bandwidth that does not interfere with this (such as a 1 MHz band that does not overlap with the 4 MHz band in the case of IEEE. 11ah). Thus, in this embodiment, in principle, a wider bandwidth than that of the second link 20 is given to the first link 18. And the transmission period of the first link 18 and the transmission period of the second link 20 are calculated based on the transmission rate considering their bandwidths.

[0039] [Example of calculation of transmission period (Part 1)] FIG. 7 is a timing chart for explaining an example of the transmission period set based on the transmission rate by the system of this embodiment. In the network of this embodiment, as described above, packet congestion is likely to occur in the first STA 12 responsible for the relay process. Therefore, the setting of the transmission period is first performed for the first STA 12, that is, for the first link 18. And the transmission periods related to other terminals and the parent device are determined in accordance with the transmission period of the first link 18.

[0040] The packet received by the first STA12 from the first AP10 for relaying becomes the transmission packet addressed to the second STA16 as it is. Also, the packet received by the first STA12 from the second STA16 becomes the transmission packet addressed to the first AP10. Therefore, by calculating the ratio of the packet transmission time to the packet reception time as the transmission period, the balance between transmission and reception can be achieved.

[0041] For example, if the optimal transmission rate for the first link 18 is determined as M1 from the propagation path loss and noise power, the frame time length Ta1 can be calculated as Ta1 = f(M1) as a function of M1. On the other hand, for the second link 20 as well, if the optimal transmission rate is determined as M2, the frame time length Ta2 can be calculated as Ta2 = f(M2) as a function of M2. However, when there are multiple terminals functioning as the second STA16, the minimum value, average value, or median value of those transmission rates is selected as a representative value, and the frame time length Ta2 is calculated based on that representative value. Also, if there are transmission rates or traffic rates set in the application being used, those values are referred to.

[0042] Once the packet time length Ta1 of the first link 18 and the packet time length Ta2 of the second link 20 can be calculated, next, the transmission period in the overall cycle is set by the following calculation formula. Transmission period of the first link 18 = Ta1 / (Ta1 + Ta2) ···(1) Transmission period of the second link 20 = Ta2 / (Ta1 + Ta2) ···(2)

[0043] Figure 8 is a flowchart for explaining the processing flow performed by the first STA12 to set the transmission period by the above method. According to the routine shown in Figure 8, first, the first STA12 acquires the optimal transmission rate M1 for the first link 18 (step 100). Next, the packet time length Ta1 = f(M1) required for transmission at the acquired transmission rate M1 is calculated (step 102).

[0044] Similarly, an optimal transmission rate M2 is obtained for the second link 20 (step 104). Further, based on M2, the packet time length Ta2 = f(M2) of the second link 20 is calculated (step 106). Subsequently, the overall period is set according to the above equations (1) and (2) (step 108).

[0045] When the above processing is completed, processing for sharing the transmission period of the first link 18 and the transmission period of the second link 20 among devices belonging to the network is performed (step 110). Specifically, by an access control method compliant with wireless system standards such as the above-described TWT and RAW, wireless transmission by the first AP 10 and the first STA 12 is prohibited outside the transmission period of the first link 18, and wireless transmission by the second AP 14 and the second STA 16 is prohibited outside the transmission period of the second link 20. However, the method of prohibiting wireless transmission is not limited to this. For example, the function may be realized by control from an upper layer, software inspected for the firmware of a wireless device, or the like.

[0046] According to the above processing, it is possible to set a transmission period suitable for transmitting data at the optimal transmission rate M1 or M2 for each of the first link 18 and the second link 20. Therefore, packets do not get stuck in the first STA 12 responsible for relaying, and the above-described packet loss problem can be solved.

[0047] Also, according to the above processing, it is possible to avoid the wireless signal transmitted on the first link 18 and the wireless signal to be transmitted on the second link 20 from being sent out overlappingly. Therefore, different from the case of using the CSMA / CA method, it is possible to appropriately avoid the collision of data frames as described with reference to FIGS. 4 or 5.

[0048] [Calculation Example of Transmission Period (Part 2)] FIG. 9 is a timing chart for explaining an example of a transmission period set by the system of the present embodiment based on the time limit of the transmission time. In the network of the present embodiment, as described above, packet congestion is likely to occur in the first STA12 responsible for the relay process. And when a time limit for transmission time is imposed on the terminal at the relay point, if the first STA12 accepts relay traffic exceeding the limit, packet loss will occur in the first STA12. For this reason, in the present embodiment, the number of packets Np accepted by the first STA12 is set according to the time limit.

[0049] For example, when the network of the present embodiment is used in the normal environment of IoT, it is considered that a large amount of upstream traffic occurs. In this case, in order to relay the traffic, the number of packets Np that can be received by the first STA12 is calculated from the transmission time limit (for example, 360 sec per hour), the transmission rate, and the retransmission rate. And the transmission time Tb1 required to transmit the number of packets Np is calculated. Specifically, the time obtained by adding the time required for one transmission based on the access frequency calculated from the surrounding OBSS (Overlapping Basic Service Set) to the time during which the wireless signal of the number of packets Np can be transmitted is calculated as Tb1.

[0050] Next, the transmission time Tb2 required to transmit the above number of packets Np to the second AP14 is calculated. This transmission time Tb2 is calculated based on the transmission rate assumed in the second link 20 (when there are a plurality of terminals, a representative rate such as the average value of the rates for each terminal) and the access frequency calculated from the number of surrounding OBSSs.

[0051] When the transmission time Tb1 for transmitting the number of packets Np in the first link 18 and the time Tb2 required for the second AP14 to receive the number of packets Np via the second link 20 can be calculated, next, the transmission period in the entire cycle is set by the following calculation formula. Transmission period of the first link 18 = Tb1 / (Tb1 + Tb2) ···(3) Transmission period of the second link 20 = Tb2 / (Tb1 + Tb2) ···(4)

[0052] FIG. 10 is a flowchart for explaining the flow of processing performed by the first STA 12 to set the transmission period by the above-described method. According to the routine shown in FIG. 10, first, on the premise of transmitting on the first link 18, the number of packets Np that the first STA 12 can receive is calculated (step 120). Next, the transmission time Tb1 of the number of packets Np is calculated by the above-described method (step 122).

[0053] Next, the time Tb2 required for the second AP 14 to receive the number of packets Np via the second link 20 is calculated (step 124). Subsequently, the overall period is set according to the above equations (3) and (4) (step 126).

[0054] When the above processing is completed, processing for sharing the transmission period of the first link 18 and the transmission period of the second link 20 among the devices of the network is performed (step 128). Specifically, wireless transmission by the first AP 10 and the first STA 12 is prohibited outside the transmission period of the first link 18, and processing for prohibiting wireless transmission by the second AP 14 and the second STA 16 outside the transmission period of the second link 20 is executed. The processing of this step 128 is realized by access control such as TWT and RAW, control from the upper layer, control by software with firmware, etc., in the same manner as in the case of step 110 above.

[0055] According to the above processing, it is possible to prevent packets exceeding the number of packets Np that can be received from being sent to the first STA 12. Therefore, packets do not get stuck in the first STA 12 responsible for relaying, and it is possible to prevent packet loss from occurring in the first STA 12.

[0056] Also, according to the above processing, similar to the case of the processing shown in FIG. 8, it is possible to avoid the situation where the radio signal transmitted on the first link 18 and the radio signal to be transmitted on the second link 20 are transmitted redundantly. Therefore, also by the processing shown in FIG. 10, it is possible to appropriately avoid the collision of data frames as described with reference to FIG. 4 or FIG. 5.

[0057] [Modification Example of Embodiment 1] By the way, in the above-described Embodiment 1, the procedure of "Calculation Example of Transmission Period (Part 2)" is described assuming a case where a large amount of upstream traffic occurs, but the calculation in the case where a large amount of downstream traffic occurs can be performed in the same manner. For example, in an IoT system, when providing an update program for updating each device, assuming that a large amount of downstream traffic occurs, the calculation method may be switched to the following method.

[0058] That is, when a large amount of downstream traffic occurs, even if the first AP 10 transmits within the time limit for transmitting a radio signal, the transmission rate of the second AP 14 that relays the transmission may be low, or the second AP 14 may not be able to sufficiently transmit packets due to interference from OBSS. In such a case, it is conceivable to take a balance for the purpose of restricting the transmission period of the first link 18. Specifically, the number of packets Np2 that can be transmitted on the second link 20 may be calculated first, and based on the Np2, the transmission periods of each link may be set.

[0059] Also, in the above-described Embodiment 1, the process of calculating the transmission period of each link and making the result known in the network is executed by the first STA 12 having the relay function. However, the device that executes the process is not limited to the first STA 12. For example, the above process may be executed by the first AP 10.

[0060] Embodiment 2. [Configuration of Embodiment 2] Next, Embodiment 2 of the present disclosure will be described with reference to FIGS. 11 to 13. FIG. 11 shows an example of a network including the wireless communication monitoring system according to Embodiment 2 of the present disclosure. In FIG. 11, elements corresponding to the elements shown in FIG. 1 above are denoted by common reference numerals, and the description thereof will be omitted or simplified.

[0061] As shown in FIG. 11, in the network of the present embodiment, a plurality of tree configurations are formed below the first AP 10. Specifically, in addition to a plurality of second STAs 16 that directly communicate with the first AP 10, a first tree 46 and a second tree 48 are connected.

[0062] The first tree 46 and the second tree 48 each have a first STA 12 that performs a relay function and a second STA 16 that communicates with the first AP 10 via the first STA 12. Thus, in the present embodiment, a first link 18 and a second link 20, which are paths for wireless communication, are formed in each of the first tree 46 and the second tree 48.

[0063] [Features of Embodiment 2] FIG. 12 is a timing chart for explaining the outline of the communication rules adopted in the present embodiment. More specifically, the upper part of FIG. 12 shows the transmission period (hatched period) of the first link 18 and the transmission period (blank period) of the second link 20 set for the first tree 46. Also, the lower part of FIG. 12 shows the transmission period (hatched period) of the first link 18 and the transmission period (blank period) of the second link 20 set for the second tree 48.

[0064] The transmission period of the first tree 46 and the transmission period of the second tree 48 are set in the same manner as in the case of Embodiment 1. Therefore, in any of the trees, the transmission period of the first link 18 and the transmission period of the second link 20 are set so as not to overlap within each tree. Also, their transmission periods are set so as to maintain a balance so that packet congestion does not occur at the relay point.

[0065] When a Mesh configuration or a tree configuration with multiple branches is used as in the network in this embodiment, if the transmission period of the first link 18 in one tree configuration overlaps with the transmission period of the first link 18 in another tree configuration, frame collisions are likely to occur. For this reason, in this embodiment, after synchronizing the wireless LAN repeaters with each other, information on the transmission cycle in each tree configuration is exchanged between them. Then, each repeater (first STA 12) of each individual tree is made to select its own transmission cycle so as not to overlap with the transmission cycles of the surrounding repeaters (first STA 12).

[0066] Synchronization between repeaters can be achieved by the Time Sync method. Alternatively, a method of calculating the relative time from the Time Stamp in each wireless LAN frame to indicate the transmission cycle may be adopted. Also, timing control based on TBTT (Target Beacon Transfer Time) may be performed so that the first AP 10 does not become an exposed terminal. Furthermore, frame collisions can be suppressed by making the transmission periods in the network known to all.

[0067] FIG. 13 is a flowchart for explaining the flow of processing executed by the first STA 12 arranged in each tree in order to realize the above functions. According to the routine shown in FIG. 13, the first STA 12 first acquires information on the transmission period or transmission cycle set in other trees (step 130).

[0068] Next, processing for minimizing the overlap of the transmission periods is executed (step 132). If a plurality of trees set the transmission periods of the first link 18 and the second link 20 aiming for optimization in each tree, a certain degree of overlap of the transmission periods will occur between adjacent trees. Here, for a plurality of trees, its own transmission cycle is determined with respect to the transmission cycles of other trees so that the overlap of the transmission periods between the first links 18 and the overlap of the transmission periods between the second links 20 are minimized.

[0069] Thereafter, a process for sharing the set transmission period among each device in the network is executed (step 134). As a result, in each individual tree, each device performs transmission processing according to the transmission period set for each tree and the transmission period. Thereby, collisions between a plurality of tree configurations are minimized, and efficient communication is realized throughout the network.

Explanation of Signs

[0070] 10 First parent device (first AP) 12 First child device and relay device (first STA) 14 Second parent device (second AP) 16 Second child device (second STA) 18 First link 20 Second link 22, 36 Control unit 24, 38 Transmission unit 26, 40 Reception unit

Claims

1. A wireless communication monitoring method for managing wireless communication in a network having a first link of wireless communication between a relay device and a master device and a second link of wireless communication between the relay device and a slave device, comprising: setting a first transmission time for permitting transmission on the first link based on a first transmission amount to be communicated on the first link; setting a second transmission time for permitting transmission on the second link based on a second transmission amount to be communicated on the second link; determining an overall transmission cycle based on the first transmission time and the second transmission time, and determining a first transmission period corresponding to the first transmission time and a second transmission period corresponding to the second transmission time so as not to overlap with each other within the overall transmission cycle; controlling wireless devices included in the network such that wireless transmission to be performed on the first link is restricted to the first transmission period and wireless communication to be performed on the second link is restricted to the second transmission period; A wireless communication monitoring method including the above steps.

2. obtaining a first transmission rate M1 to be achieved on the first link; obtaining a second transmission rate M2 to be achieved on the second link, and the first transmission time is set based on the first transmission rate M1, the wireless communication monitoring method according to claim 1, wherein the second transmission time is set based on the second transmission rate M2.

3. When it is assumed that the network is used in an environment where more uplink traffic occurs than downlink traffic, further comprising calculating a number of packets Np that the relay device can receive on the premise of transmitting to the first link, the first transmission time is set based on the time required to transmit the number of packets Np on the first link, the wireless communication monitoring method according to claim 1, wherein the second transmission time is set based on the time required to upload the number of packets Np to the relay device through the second link.

4. When it is assumed that the network is used in an environment where more downlink traffic occurs than uplink traffic, further comprising calculating a number of packets Np that the relay device can receive on the premise of transmitting to the second link, the second transmission time is set based on the time required to transmit the number of packets Np on the second link, The wireless communication monitoring method according to claim 1, wherein the first transmission time is set based on the time required to download the number of packets Np to the relay device through the first link.

5. The wireless communication monitoring method according to any one of claims 1 to 4, wherein a bandwidth wider than the bandwidth used by the second link is allocated to the first link.

6. The network includes a plurality of relay devices that each relay the first link and the second link, The wireless communication monitoring method according to any one of claims 1 to 5, further comprising the step of setting the entire transmission cycle so that the overlap between the first transmission periods and the overlap between the second transmission periods between at least one of the plurality of relay devices and other relay devices are minimized.

7. A wireless communication monitoring system including a network having a first link for wireless communication between a relay device and a parent device and a second link for wireless communication between the relay device and a child device, by at least one or both of the relay device and the parent device, a process of setting a first transmission time for permitting transmission to the first link based on a first transmission amount to be communicated on the first link; a process of setting a second transmission time for permitting transmission to the second link based on a second transmission amount to be communicated on the second link; a process of determining an entire transmission cycle based on the first transmission time and the second transmission time, and determining a first transmission period corresponding to the first transmission time and a second transmission period corresponding to the second transmission time so as not to overlap with each other within the entire transmission cycle; a process of controlling wireless devices included in the network so that wireless transmission to be performed on the first link is restricted to the first transmission period and wireless communication to be performed on the second link is restricted to the second transmission period; A wireless communication monitoring system configured to be executed.

8. A wireless communication monitoring device for managing wireless communication in a network having a first link for wireless communication between a relay device and a parent device and a second link for wireless communication between the relay device and a child device, a process of setting a first transmission time for permitting transmission to the first link based on a first transmission amount to be communicated on the first link; a process of setting a second transmission time for permitting transmission to the second link based on a second transmission amount to be communicated on the second link; Determine an overall transmission period based on the first transmission time and the second transmission time, and in the overall transmission period, determine a first transmission period corresponding to the first transmission time and a second transmission period corresponding to the second transmission time so as not to overlap with each other. Control the wireless devices included in the network so that the wireless transmission to be performed on the first link is restricted to the first transmission period, and the wireless communication to be performed on the second link is restricted to the second transmission period. A wireless communication monitoring device configured to execute the above.

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