JP4767062B2 - Wireless access point and control device for managing the wireless access point - Google Patents

Wireless access point and control device for managing the wireless access point Download PDF

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JP4767062B2
JP4767062B2 JP2006092444A JP2006092444A JP4767062B2 JP 4767062 B2 JP4767062 B2 JP 4767062B2 JP 2006092444 A JP2006092444 A JP 2006092444A JP 2006092444 A JP2006092444 A JP 2006092444A JP 4767062 B2 JP4767062 B2 JP 4767062B2
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map
link
wireless
capacity
access point
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JP2007267281A (en
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ジャトゥロン サギャムウォン
藤原  淳
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株式会社エヌ・ティ・ティ・ドコモ
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Description

  The present invention relates to a wireless access point constituting a wireless mesh network and a control device that manages the wireless access point.

  In recent years, in a wireless mesh network including a plurality of wireless access points, attention has been focused on using a directional antenna capable of improving the utilization efficiency and gain of spatial frequency instead of an omni antenna having no directivity. Yes.

  Further, in a wireless mesh network using a directional antenna, it is possible to improve the use efficiency of spatial frequency instead of the MAC protocol based on CSMA (Carrier Sense Multiple Access) adopted in IEEE802.11 or the like. Therefore, a MAC protocol for dynamically controlling the directivity of a directional antenna has been proposed.

  On the other hand, in the MAC protocol that dynamically controls the directivity of the directional antenna, new problems such as “new hidden terminal problem” and “deafness problem” occur, In some cases, the capacity decreased.

  Therefore, in a wireless mesh network, a technique has been proposed in which a MAC protocol based on CSMA is used and an omni antenna is used as a receiving antenna while a directional antenna is used as a transmitting antenna (for example, Patent Document 1).

  According to this technology, it is possible to improve the capacity of the wireless mesh network while suppressing the occurrence of the “new hidden terminal problem” and the “deafness problem”.

In general, in the above-described technique, when selecting a combination of wireless access points for establishing a wireless link and performing route selection, the load of the wireless access points is distributed to improve the capacity of the wireless mesh network. Is planned.
JP 2000-115171 A (Claim 7, Claim 8, etc.)

  However, just by distributing the load of the wireless access point as in the above-described technique, the radio wave transmitted by one wireless access point to establish one wireless link is transmitted to the wireless access point that establishes another wireless link. May cause interference.

  Therefore, the capacity of the wireless mesh network may be reduced only by distributing the load of the wireless access points.

  Accordingly, the present invention has been made to solve the above-described problems, and provides a wireless access point capable of improving the capacity of a wireless mesh network and a control device that manages the wireless access point. With the goal.

  One feature of the present invention is that a control device (control device 30) that manages a plurality of wireless access points (MAP 10a to MAP 10f) that establish a wireless link in a wireless mesh network in which a plurality of wireless links is established includes the wireless link. An interfering link information acquisition unit (communication unit 31) that acquires interfering link information indicating that an interfering link that is one of the interference links interferes with an interfered link that is one of the radio links; Based on the interference link information acquired by the link information acquisition unit, a setting determination unit (parameter determination unit 33) that determines the setting of the radio link, and the setting of the radio link determined by the setting determination unit. , A setting notification part (message And summarized in that it comprises a generation unit 35) and.

  According to this feature, the setting determination unit determines the radio link setting based on the interfering link information acquired by the interfering link information acquisition unit. In consideration of the above, the setting of the radio link is determined.

  Therefore, the capacity of the wireless mesh network can be improved as compared with the case where the route selection is performed in consideration of only the transmission rate.

  According to one aspect of the present invention, in the one aspect described above of the present invention, the setting determination unit includes a directivity of a radio wave transmitted by the interfering access point and the wireless that the interfering access point establishes the radio link. The gist is to determine an access point as the setting of the wireless link.

  One aspect of the present invention is that, in the above-described one aspect of the present invention, the setting determination unit determines transmission power of a radio wave transmitted by the interfering access point as a setting of the wireless link. .

  One feature of the present invention is the wireless mesh network corresponding to the setting of the wireless link that has been set before the setting of the wireless link is determined by the setting determination unit in the one feature of the present invention described above. A network capacity comparison unit (capacity comparison unit 34) that compares the pre-determination capacity that is the capacity of the wireless mesh network and the post-determination capacity that is the capacity of the wireless mesh network corresponding to the setting of the wireless link determined by the setting determination unit And the setting notification unit notifies the interference access point of the setting of the radio link determined by the setting determination unit when the post-determination capacity is larger than the pre-determination capacity. This is the gist.

  According to one aspect of the present invention, in the one aspect of the present invention, the network capacity comparison unit considers an influence of a hidden terminal problem according to a configuration of the wireless mesh network, and determines the capacity of the wireless mesh network. The gist is to calculate.

  One feature of the present invention is that a wireless access point (MAP 10) constituting a wireless mesh network has received interference from an interference link that is a wireless link extended by another wireless access point constituting the wireless mesh network. When the interference detection unit (interference detection unit 18) to detect and the interference detection unit detect that the interference by the interfering link is detected, the interference suppression by the interfering link is suppressed to the other radio access point. And an interference suppression requesting unit (message generating unit 19) that requests the above.

  According to such a feature, the interference suppression request unit requests that other wireless access points that have the interfering link interfere with the interfering link, thereby receiving interference from the interfering link. The wireless access point is notified.

  Accordingly, the other wireless access point can determine the setting of the wireless link in consideration of the influence of the interference given by the interfering link in response to a request from one wireless access point.

  In addition, the wireless access point can autonomously determine the setting of the wireless link without providing a control device that centrally manages each wireless access point, and selects a route by considering only the transmission rate. The capacity of the wireless mesh network can be improved as compared with the case where it is performed.

  One feature of the present invention is that, in the above-described feature of the present invention, the interference suppression request unit requests the other wireless access point to suppress transmission power of a radio wave transmitted by the other wireless access point. This is the gist.

  One feature of the present invention is that in the one feature described above of the present invention, the interference suppression requesting unit requests the other wireless access point to change the directivity of the radio wave transmitted by the other wireless access point. This is the gist.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus which manages the wireless access point which can aim at the improvement of the capacity | capacitance of a wireless mesh network, and this wireless access point can be provided.

[First Embodiment]
(Network configuration)
Hereinafter, the configuration of the network according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a network configuration according to the first embodiment of the present invention.

  As illustrated in FIG. 1, the network includes a plurality of mesh access points 10 (MAP 10 a to MAP 10 f), a plurality of gateways 20 (GW 20 a to GW 20 b), and a control device 30. In the following description, the mesh access point 10 is simply referred to as MAP10, and the gateway 20 is referred to as unit GW20.

  The MAP 10 establishes a wireless link with another MAP 10 and configures a wireless mesh network. Each MAP 10 functions as a directional antenna having directivity when transmitting a signal to another MAP 10, and is not directional when receiving a signal from another MAP 10. It has a transmission / reception antenna that functions as a directional antenna (omni antenna). The MAP 10 may have a directional antenna used for signal transmission and an omnidirectional antenna used for signal reception separately.

  The GW 20 has a wireless link with some of the MAPs 10 (MAP 10a and MAP 10d), and is connected to the control device 30 by a wired LAN 40. The LAN 40 is, for example, Ethernet (registered trademark).

  The control device 30 is connected to each GW 20 via the LAN 40 and manages a plurality of MAPs 10 via the GW 20. Specifically, the control device 30 manages combinations (routes) of MAPs 10 that establish wireless links, and selects (routes selection) combinations of MAPs 10 that establish wireless links so that the load on the MAPs 10 is distributed. I do.

(Concept of control by control device)
The concept of control by the control device according to the first embodiment of the present invention will be described below with reference to the drawings. 2-4 is a figure which shows the concept of control by the control apparatus 30 which concerns on 1st Embodiment of this invention.

  2 to 4, a range a is a range where radio waves transmitted by the MAP 10 reach, and is a range in which a wireless link can be established at a first transmission rate (for example, 54 Mbps). The range b is a range in which the radio wave transmitted by the MAP 10 reaches, and is a range in which a wireless link can be established at a second transmission rate (for example, 24 Mbps). Furthermore, the range c is a range where radio waves transmitted by the MAP 10 reach and is a range that interferes with other MAPs 10.

  First, the case where the control device 30 performs route selection considering only the transmission rate will be described with reference to FIG.

  As illustrated in FIG. 2, the control device 30 performs route selection so that the transmission rate of each wireless link is the fastest, and distributes the load of the MAP 10. Specifically, each wireless link is extended between one MAP 10 and another MAP 10 located within a range a within which radio waves transmitted by one MAP 10 reach, and has a first transmission rate. is doing.

  In the first embodiment, as a result of performing route selection considering only the transmission rate, the MAP 10a to MAP 10c are connected to the LAN 40 via the GW 20a, so the GW 20a and the MAP 10a to MAP 10c constitute the domain 1. . On the other hand, since the MAPs 10d to 10f are connected to the LAN 40 via the GW 20b, the GW 20b and the MAPs 10d to MAP 10f constitute the domain 2.

  As described above, when the control device 30 selects a route in consideration of only the transmission rate, one wireless link may interfere with another wireless link.

  In the following, one radio link that interferes with another radio link is referred to as an interfering link, and another radio link that is interfered with by one radio link is referred to as an interfered link. In addition, the MAP 10 that transmits a radio wave that interferes with the interfered link is referred to as an interfered access point, and the MAP 10 that receives interference by the interfered link is referred to as an interfered access point.

  Specifically, the radio link that the MAP 10c extends to the MAP 10b is an interfering link that interferes with the radio link that the MAP 10e extends to the MAP 10d. That is, since the MAP 10d is located within the range c where the radio wave transmitted by the MAP 10c reaches, the radio wave transmitted by the MAP 10c interferes with the radio wave received by the MAP 10d from the MAP 10e.

  As described above, when the control device 30 performs route selection considering only the transmission rate, the interfering link may interfere with the interfered link, and the capacity of the wireless mesh network may be reduced.

  Next, a case where the control device 30 controls the directivity of the radio wave transmitted by the MAP 10 in consideration of the interference state will be described with reference to FIG. FIG. 3 is a diagram showing a state in which the directivity of radio waves is controlled from the state shown in FIG.

  As illustrated in FIG. 3, the control device 30 controls the directivity of the radio wave transmitted by the MAP 10 in consideration of the interference state. Specifically, in the state shown in FIG. 2, the control device 30 interferes with the radio link that the MAP 10c extends to the MAP 10b and the radio link that the MAP 10e extends to the MAP 10d, so that the directivity of the radio wave transmitted by the MAP 10c and the MAP 10e is increased. By controlling, the MAP 10c and the MAP 10e change the MAP 10 that establishes a radio link.

  That is, the control device 30 changes the MAP 10 with which the MAP 10c establishes a radio link from MAP 10b to MAP 10a, and the MAP 10e changes the MAP 10 with which the radio link is established from MAP 10d to GW 20b.

  Here, if the MAP 10c and the MAP 10e change the MAP 10 that establishes the radio link, the path length of the radio link that the MAP 10c and the MAP 10e establishes becomes longer. Therefore, although the transmission rate of the radio link spanned by the MAP 10c and the MAP 10e is reduced from the first transmission rate to the second transmission rate, the interference state is eliminated.

  As described above, when the control device 30 controls the directivity of the radio wave transmitted by the MAP 10 in consideration of the interference state, the transmission rate of the wireless link may be reduced. Network capacity can be improved.

  Finally, a case where the control device 30 controls the transmission power of the radio wave transmitted by the MAP 10 in consideration of the interference state will be described with reference to FIG. FIG. 4 is a diagram illustrating a state in which radio wave transmission power is controlled from the state illustrated in FIG. 2.

  As illustrated in FIG. 4, the control device 30 controls the transmission power of the radio wave transmitted by the MAP 10 in consideration of the interference state. Specifically, in the state shown in FIG. 2, the control device 30 reduces the transmission power of the radio wave transmitted by the MAP 10c because the radio link established by the MAP 10c and the MAP 10b interferes with the radio link established by the MAP 10e. Further, in the state shown in FIG. 2, the control device 30 reduces the transmission power of the radio wave transmitted by the MAP 10e because the radio link established by the MAP 10e and the MAP 10d interferes with the radio link established by the MAP 10a and the GW 20a.

  Thus, when the transmission power of the radio waves transmitted by the MAP 10c and the MAP 10e is reduced, the reach range of the radio waves transmitted by the MAP 10c and the MAP 10e is reduced. Therefore, although the transmission rate of the radio link spanned by the MAP 10c and the MAP 10e is reduced from the first transmission rate to the second transmission rate, the interference state is eliminated.

  In this way, when the control device 30 controls the transmission power of the radio wave transmitted by the MAP 10 in consideration of the interference state, the transmission rate of the wireless link may be reduced. Network capacity can be improved.

(Configuration of control device)
The configuration of the control device according to the first embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a block diagram showing a configuration of the control device 30 according to the first embodiment of the present invention.

  As illustrated in FIG. 5, the control device 30 includes a communication unit 31, a network information management unit 32, a parameter determination unit 33, a capacity comparison unit 34, and a message generation unit 35.

  The communication unit 31 communicates with each MAP 10 via the GW 20. Specifically, the communication unit 31 receives from the one MAP 10 a message indicating that the radio link established by one MAP 10 has received interference from the radio link established by another MAP 10. In addition, the communication unit 31 receives a message indicating the traffic amount of the radio link established by the MAP 10 and the number of retransmissions.

  In addition, the communication unit 31 transmits a message instructing a change of the parameter set in the MAP 10 to the MAP 10 (interfering access point). The parameters include the directivity of the radio wave transmitted by the MAP 10, the combination (route information) of the MAP 10 that establishes the radio link, the transmission power of the radio wave that the MAP 10 transmits, the transmission rate of the radio link that the MAP 10 extends, and the like.

  The network information management unit 32 manages the topology of the wireless mesh network (identifier and position of the MAP 10 constituting the wireless mesh network) as network information.

  In addition, the network information management unit 32 determines the traffic volume and the wireless mesh network of communication (wireless link) performed by the MAP 10 configuring the wireless mesh network according to the message received by the communication unit 31 from the MAP 10 configuring the wireless mesh network. The amount of interference received by the configured MAP 10 is managed as network information.

  Furthermore, the network information management unit 32 manages not only the network information corresponding to the wireless link currently extended by the MAP 10 but also the network information corresponding to the wireless link extended by the MAP 10 in the past.

  The parameter determination unit 33 determines a parameter set in the MAP 10. Specifically, the parameter determination unit 33 is configured such that the directivity of the radio wave transmitted by the MAP 10, the combination (route information) of the MAP 10 that establishes the radio link, the transmission power of the radio wave that the MAP 10 transmits, the transmission rate of the radio link that the MAP 10 extends, etc. To decide.

  The parameter determination unit 33 also determines the capacity (predicted network capacity) of the wireless mesh network corresponding to the newly determined parameter rather than the capacity (current network capacity) of the wireless mesh network corresponding to the parameter currently set in the MAP 10. Is large, the newly determined parameter is input to the message generator 35.

Here, the capacity of the wireless mesh network is the total capacity of each flow. The capacity of each flow is expressed as L f / T f when the average number of successful reception bits (L f ) of the flow is taken and the required time for the flow is (T f ). The flow is a flow of a radio link up to the GW 20.

  The capacity comparison unit 34 refers to the network information managed by the network information management unit 32 and compares the current network capacity with the predicted network capacity. A method for calculating the capacity of the wireless mesh network will be described later (FIGS. 7 to 12).

  The message generation unit 35 generates a message instructing to change the parameter set in the MAP 10 (interfering access point) to the parameter acquired from the parameter determination unit 33. In addition, the message generator 35 inputs the generated message to the communication unit 31.

(Mesh access point configuration)
Hereinafter, the configuration of the mesh access point according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram showing a configuration of the MAP 10 according to the first embodiment of the present invention.

  As shown in FIG. 6, the MAP 10 includes an antenna 11, a communication unit 12, a message processing unit 13, a directivity control unit 14, a transmission power control unit 15, a transmission rate control unit 16, and a routing information storage unit. 17, an interference detection unit 18, and a message generation unit 19.

  The antenna 11 functions as a receiving antenna that receives radio waves from other MAPs 10 constituting the wireless mesh network and a transmission antenna that transmits radio waves to other MAPs 10 constituting the wireless mesh network. Here, when the antenna 11 functions as a receiving antenna, the antenna 11 is a non-directional antenna (omni antenna) having no directivity. On the other hand, when the antenna 11 functions as a transmission antenna, it is a directional antenna having directivity. In addition, the directivity of the radio wave transmitted by the antenna 11 is controlled by a directivity control unit 14 described later, and the transmission power of the radio wave transmitted by the antenna 11 is controlled by a transmission power control unit 15 described later.

  The antenna 11 may be configured to have a receiving antenna and a transmitting antenna separately.

  The communication unit 12 communicates with other MAPs 10 constituting the wireless mesh network, and has a packet retransmission control function and the like. Specifically, the communication unit 12 communicates with another MAP 10 at a transmission rate controlled by a transmission rate control unit 16 described later, and uses routing information (route information) stored in a routing information storage unit 17 described later. It communicates with other determined MAPs 10.

  The communication unit 12 communicates with the control device 30 via the GW 20. Specifically, the communication unit 12 receives from the control device 30 a message for instructing change of parameters set in the MAP 10. In addition, the communication unit 12 transmits a message indicating that interference is received from the radio link established by another MAP 10 to the control device 30.

  The message processing unit 13 processes a message received from the control device 30. Specifically, the message processing unit 13 instructs the directivity control unit 14, the transmission power control unit 15, and the transmission rate control unit 16 to change each parameter according to the message received from the control device 30. Further, the message processing unit 13 rewrites the routing information stored in the routing information storage unit 17 in accordance with the message received from the control device 30.

  The directivity control unit 14 controls the directivity of the radio wave transmitted by the antenna 11 in accordance with an instruction from the message processing unit 13.

  The transmission power control unit 15 controls the transmission power of the radio wave transmitted by the antenna 11 in accordance with an instruction from the message processing unit 13.

  The transmission rate control unit 16 controls the transmission rate of communication (wireless link) performed by the communication unit 12 in accordance with an instruction from the message processing unit 13.

  The routing information storage unit 17 stores routing information (route information) indicating a combination of MAPs 10 that establish a wireless link. That is, the routing information storage unit 17 stores the MAP 10 that is a counterpart with which the communication unit 12 communicates.

  The interference detection unit 18 detects that interference is received from a radio link provided by another MAP 10. Specifically, the interference detection unit 18 detects the amount of interference received from a radio link provided by another MAP 10 and the packet loss caused by the interference. In addition, the interference detection unit 18 inputs the detected interference amount and packet loss to the message generation unit 19.

  In response to the interference amount and packet loss acquired from the interference detection unit 18, the message generation unit 19 sends a message including the interference amount and packet loss (message indicating that interference is received from the radio link established by another MAP 10). Generate. The message generator 19 inputs the generated message to the communication unit 12.

(Calculation method for wireless mesh network capacity)
Hereinafter, a method for calculating the capacity of the wireless mesh network according to the first embodiment of the present invention will be described with reference to the drawings. 7 to 8 are diagrams illustrating a method of calculating the capacity of the wireless mesh network according to the first embodiment of the present invention.

  First, the case where the number of hops is one and the packet is successfully received at the first time will be described with reference to FIG.

  As shown in FIG. 7A, the packet includes a DIFS (Distributed Interframe Space), a backoff, a data frame, a SIFS (Short Interframe Space), and reception confirmation data (ACK).

  When one MAP 10 transmits a packet to another MAP 10, the other MAP 10 does not return the reception confirmation data (ACK) to the one MAP 10 if the packet cannot be received correctly. On the other hand, if one MAP 10 does not receive the acknowledgment data (ACK) from the other MAP 10, it retransmits the packet to the other MAP 10.

Accordingly, the required time (T f ) for transmitting a packet with a data frame length of L is the total time of “DIFS + backoff + data frame + SIFS + reception confirmation data” in IEEE 802.11. The time required for transmission of DIFS and SIFS is standardized by IEEE 802.11, and the time required for transmission of data frames and reception confirmation data depends on the transmission rate of the radio link.

  Next, a case will be described with reference to FIG. 7B where the number of hops is one, the packet reception fails at the first time, and the packet reception is successful at the second time.

As shown in FIG. 7B, since the packet reception failed at the first time, the required time (T f ) for transmitting the packet with the data frame length L is “DIFS + backoff + data frame. + SIFS + reception confirmation data ".

  The average required time for the first backoff transmission is represented by “0.5 × slot time × CWmin”, and the average required time for the second backoff transmission is “0.5 × slot. Time × (2 × CWmin + 1) ”. CWmin is the minimum value of the contention window.

  Next, a case where the number of hops is 3 and packet reception has failed at the first time of the second hop will be described with reference to FIG.

As shown in FIG. 8, since the number of hops is 3, and the packet reception has failed once, the required time (T f ) for transmitting the packet with the data frame length L is “DIFS + back It is four times "off + data frame + SIFS + reception confirmation data".

  As described above, the time required for transmission of a packet having a data frame length L depends on the transmission rate of the radio link, the number of hops, and the number of packet reception failures (number of retransmissions).

  Here, in the first embodiment, the average number of successful reception bits and the required time of each flow are calculated to calculate the total capacity of the domain, and the total capacity of each domain is totaled to calculate the capacity of the wireless mesh network. Is calculated. As shown in FIG. 1, in the first embodiment, the wireless mesh network includes a domain 1 having a GW 20a and MAPs 10a to MAP 10c, and a domain 2 having a GW 20b and MAPs 10d to MAP 10f.

Here, when the number of hops (the number of radio links) is N and the maximum number of retransmissions is R, the number of flow patterns in which a packet is transmitted is expressed by the following equation.

In the following, the communication success probability of hop i (radio link i) is p i , the number of retransmissions in hop i (radio link i) is r, and the time required for communication of hop i (radio link i) is t Let i, r . Further, the time required for the communication of the pattern j is T j, and the occurrence probability of the pattern j is P j . In this case, the average number of successful reception bits (L f ) of the flow f and the time required for the flow f (T f ) are expressed by the following equations. J is the number of flow patterns.

The total capacity of the domain including the flow f is expressed by the following formula. Α is an adjustment coefficient for adjusting the influence of the “hidden terminal problem” and the “exposed terminal problem”, and F is the number of flows.

  Furthermore, the capacity of the wireless mesh network is the total of the total capacity of the domains calculated by the above-described formula.

  Finally, taking as an example a flow in which the number of hops is 2 and the maximum number of retransmissions R is 1, a method for calculating the capacity of this flow will be illustrated.

  Specifically, since the number of hops is 2 and the maximum number of retransmissions R is 1, the pattern of this flow is 7 patterns in total. FIG. 9A, FIG. 9B, FIG. 10A, FIG. 10B, FIG. 11A, FIG. 11B, and FIG. 12 are diagrams showing respective patterns. Here, FIG. 9A, FIG. 9B, FIG. 10A, and FIG. 10B are diagrams showing a case where the packet is finally successfully received, and FIG. FIG. 11B and FIG. 12 are diagrams showing a case where reception of a packet finally fails.

Here, p 1 is the probability of successful packet reception at hop 1, and p 2 is the probability of successful packet reception at hop 2.

As described above, the capacity of this flow is expressed by the following equation.

(Operation of control device)
Hereinafter, the operation of the control device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 13 is a flowchart showing the operation of the control device 30 according to the first embodiment of the present invention.

  As illustrated in FIG. 13, in step 10, the control device 30 selects a combination (path) of MAPs 10 that establish a radio link in consideration of only the fastest mode. Specifically, the control device 30 performs route selection so that the transmission rate of the radio link established by each MAP 10 is the fastest.

  In step 11, the control device 30 analyzes the state of interference occurring in the wireless mesh network according to the message received from the MAP 10 configuring the wireless mesh network. Specifically, the control device 30 determines the status of interference occurring in the wireless mesh network in response to a message received from the MAP 10 (interfered access point) that is receiving interference from a radio link established by another MAP 10. analyse.

  In step 12, the control device 30 determines whether there is a radio link (interfering link) that interferes with another radio link, according to the analysis result of step 11. Specifically, the control device 30 determines whether there is an interfering link that has not been examined as to whether or not the predicted network capacity becomes larger than the current network capacity. Further, when there is an uninterested interference link, the control device 30 proceeds to the process of step 13, and when there is no uninterested interference link, this series of processing ends.

  In step 13, the control device 30 selects an interference link according to the analysis result in step 11. The control device 30 may select the interfering links in descending order of the interference due to the interfering link.

  In step 14, the control device 30 determines parameters to be set in the MAP 10 (interfering access point) that has established the interfering link. Specifically, the control device 30 determines the directivity of the radio wave transmitted by the interfering access point and the MAP 10 (route information) on which the interfering access point establishes a radio link. The control device 30 determines radio wave directivity and route information so that the interfered access point does not receive interference.

  Also, the control device 30 determines the transmission power of the radio wave transmitted by the interfering access point. Note that the control device 30 determines the radio wave transmission power so that the radio wave transmission power is reduced to a level at which the interfered access point does not receive interference.

  Furthermore, the control device 30 determines the transmission rate of the radio link according to the determined radio wave directivity and path information, or the radio wave transmission power.

  In step 15, the control device 30 predicts the capacity of the wireless mesh network corresponding to the parameter determined in step 14.

  In step 16, the control device 30 determines the wireless mesh network capacity (predicted network capacity) predicted in step 15 and the wireless mesh network capacity (current network capacity) corresponding to the parameters currently set in each MAP 10. Compare. In addition, when the predicted network capacity is larger than the current network capacity, the control device 30 proceeds to the process of step 17, and when the predicted network capacity is equal to or less than the current network capacity, the control apparatus 30 returns to the process of step 11.

  In step 17, the control device 30 transmits a message to the MAP 10 (interfering access point) instructing to change the parameter set in the MAP 10 to the parameter determined in step 14.

(Function and effect)
According to the control device 30 according to the first embodiment of the present invention, the parameter determination unit 33 extends the interfering link when one MAP 10 (interfered access point) is interfered by the interfering link. A parameter (radio wave directivity or radio wave transmission power) set in the MAP 10 (interfering access point) is determined. That is, the parameter set in the MAP 10 is determined in consideration of the influence of the interference that the interfering link has on the interfered link.

  Therefore, the capacity of the wireless mesh network can be improved as compared with the case where the route selection is performed in consideration of only the transmission rate.

  In addition, according to the control device 30 according to the first embodiment of the present invention, the capacity comparison unit 34 newly determines the wireless mesh network capacity (current network capacity) corresponding to the parameters currently set in the MAP 10. The wireless mesh network capacity (predicted network capacity) corresponding to the selected parameter is compared. The parameter determination unit 33 inputs the newly determined parameter to the message generation unit 35 when the predicted network capacity is larger than the current network capacity.

  Therefore, the control device 30 can reliably improve the capacity of the wireless mesh network while taking into account the interference generated in the wireless mesh network.

  Furthermore, according to the control device 30 according to the first embodiment of the present invention, the capacity comparison unit 34 uses the adjustment coefficient α that adjusts the influence of the “hidden terminal problem” and the “exposed terminal problem”, and uses the wireless mesh network. By calculating the capacity of the wireless mesh network, the capacity of the wireless mesh network can be accurately calculated.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In the following, differences between the above-described first embodiment and the second embodiment will be mainly described.

  Specifically, in the first embodiment described above, the control device 30 determines the parameters set in the MAP 10 constituting the wireless mesh network. On the other hand, in the second embodiment, each MAP 10 configuring the wireless mesh network autonomously determines a parameter set in the own MAP 10 without depending on the control device 30. Therefore, in the second embodiment, the control device 30 is not provided.

(Mesh access point configuration)
The configuration of the mesh access point according to the second embodiment of the present invention will be described below with reference to the drawings. FIG. 14 is a block diagram showing a configuration of the MAP 10 according to the second embodiment of the present invention. In FIG. 14, the same components as those in FIG. 6 are denoted by the same reference numerals.

  As shown in FIG. 14, the MAP 10 includes an antenna 11, a communication unit 12a, a message processing unit 13a, a parameter determination unit 13b, a directivity control unit 14, a transmission power control unit 15, and a routing information storage unit 17. And an interference detection unit 18 and a message generation unit 19a.

  When the communication unit 12a interferes with another MAP 10 (interfered access point) by a radio link (interfering link) established by the own MAP 10, the communication unit 12a sends a parameter change message for requesting suppression of interference to the interfered access point. Receive from. On the other hand, when the own MAP 10 is interfered by a radio link (interfering link) established by another MAP 10 (interfering access point), the communication unit 12a transmits a parameter change message for requesting suppression of interference. Send to the access point.

  Here, the parameter change message includes the directivity of the radio wave transmitted by the antenna 11, the MAP 10 (path information) to which the own MAP 10 establishes a radio link, the transmission power of the radio wave transmitted by the antenna 11, and the radio link established by the own MAP 10. This message requests a change in the transmission rate. Further, the parameter change message includes an interference access point identifier, received power strength of the interference link, and the like.

  In addition, when the routing information (route information) stored in the routing information storage unit 17 is rewritten, the communication unit 12a transmits a notification message for informing the rewritten routing information to the other MAP 10. Note that the communication unit 12a may transmit the notification message only to surrounding MAPs 10 whose distance from the local MAP 10 is equal to or less than a certain distance.

  The message processing unit 13a inputs the parameter change message received from the MAP 10 that is the interfered access point to the parameter determination unit 13b.

  The parameter determination unit 13b determines each parameter to be set in the own MAP 10 according to the parameter change message acquired from the message processing unit 13a. Specifically, the parameter determination unit 13b determines the directivity of the radio wave transmitted by the antenna 11, the MAP 10 (route information) with which the own MAP 10 establishes a wireless link, the transmission power of the radio wave transmitted by the antenna 11, and the own MAP 10 Determine the transmission rate of the wireless link to be established.

  Further, the parameter determination unit 13b inputs the determined parameters to the directivity control unit 14, the transmission power control unit 15, and the transmission rate control unit 16. The directivity control unit 14, the transmission power control unit 15, and the transmission rate control unit 16 are based on the directivity of the radio wave transmitted by the antenna 11 and the radio wave transmitted by the antenna 11 according to the parameter determined by the parameter determination unit 13b. And the transmission rate of communication (wireless link) performed by the communication unit 12a.

  Furthermore, the parameter determination unit 13b rewrites the routing information storage unit 17 in accordance with the parameter determined by the parameter determination unit 13b. Specifically, the parameter determination unit 13b controls the directivity of the radio wave transmitted by the antenna 11 and determines the parameter for changing the MAP 10 to which the own MAP 10 establishes a wireless link, and stores the routing information. The routing information (route information) stored in the unit 17 is rewritten.

  When the directivity control unit 14 controls the directivity of the radio wave transmitted by the antenna 11 and the parameter determination unit 13b rewrites the routing information storage unit 17, the message generation unit 19a newly rewrites the routing information. A notification message for notifying (route information) to other MAPs 10 is generated. Also, the message generator 19a generates a parameter change message for requesting suppression of interference when the own MAP 10 is interfered by a radio link (interfering link) established by another MAP 10 (interfering access point). To do.

(Mesh access point operation)
The operation of the mesh access point according to the second embodiment of the present invention will be described below with reference to the drawings. 15 and 16 are flowcharts showing the operation of the MAP 10 according to the second embodiment of the present invention.

  First, the case where the MAP 10 is an interfered access point will be described with reference to FIG.

  As shown in FIG. 15, in step 20, the MAP 10 causes the packet loss caused by the interference received by the MAP 10 by the radio link (interfering link) established by another MAP 10 (interfering access point) exceeds a predetermined threshold. It is determined whether or not. If the packet loss exceeds a predetermined threshold, the MAP 10 moves to the process of step 21. If the packet loss is equal to or smaller than the predetermined threshold, the MAP 10 ends this series of processes.

  In step 21, the MAP 10 specifies the interfering access point according to the arrival direction of the radio wave transmitted by the interfering access point.

  In step 22, the MAP 10 transmits a parameter change message requesting interference suppression to the interfering access point. For example, the MAP 10 transmits a parameter change message including an identifier of an interfering access point, reception power of a radio wave transmitted by the interfering access point, and the like.

  Next, a case where the MAP 10 is an interfering access point will be described with reference to FIG.

  As shown in FIG. 16, in step 30, the MAP 10 receives a parameter change message from another MAP 10 (interfered access point) that is interfered by a radio link (interfering link) established by the own MAP 10.

  In step 31, the MAP 10 determines each parameter to be set in the self MAP 10. Specifically, the MAP 10 is the directivity of the radio wave transmitted by the own MAP 10, the MAP 10 (route information) to which the own MAP 10 establishes a radio link, the transmission power of the radio wave transmitted by the own MAP 10, and the radio link established by the own MAP 10 Determine the transmission rate.

  When the MAP 10 changes the directivity of the radio wave transmitted by the MAP 10 and determines a parameter for changing the MAP 10 to which the MAP 10 is to establish a wireless link, routing information (route information) of the MAP 10 is determined. Rewrite.

  In step 32, the MAP 10 determines whether or not the routing information has been rewritten. Further, when the routing information is rewritten, the MAP 10 proceeds to the process of Step 33, and when the routing information is not rewritten, the MAP 10 proceeds to the process of Step 34.

  In step 33, the MAP 10 transmits a notification message for informing the routing information rewritten in step 31 to the other MAP 10. Here, the MAP 10 may transmit the notification message only to surrounding MAPs 10 whose distance from the MAP 10 is equal to or less than a certain distance.

  In step 34, the MAP 10 determines the directivity of the radio wave transmitted by the own MAP 10, the MAP 10 (path information) to which the self MAP 10 establishes a wireless link, and the radio wave transmitted by the own MAP 10 according to the parameters determined in the step 31. Transmission power, the transmission rate of the wireless link established by the own MAP 10 and the like are controlled.

(Function and effect)
According to the MAP 10 according to the second embodiment of the present invention, the message generation unit 19 requests a parameter change message for requesting another MAP 10 (interfering access point) that has an interfering link to suppress interference due to the interfering link. Is generated. Further, the communication unit 12 transmits the parameter change message generated by the message generation unit 19 to the interfering access point.

  On the other hand, the interfering access point takes into account the influence of interference given by the interfering link according to the parameter change message received from the interfered access point, and sets the parameter (radio wave directivity or radio wave Transmission power).

  Therefore, the MAP 10 can autonomously determine parameters to be set in the MAP 10 without providing a control device that centrally manages each MAP 10 and simply selects a route in consideration of only the transmission rate. Compared to the case, the capacity of the wireless mesh network can be improved.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In the following, differences between the first embodiment and the third embodiment described above will be mainly described.

  Specifically, in the first embodiment described above, there are a plurality of GWs 20, but in the third embodiment, a single GW 20 is provided.

(Network configuration)
Hereinafter, the configuration of the network according to the third embodiment of the present invention will be described with reference to the drawings. FIG. 17 is a diagram showing a network configuration according to the third embodiment of the present invention. In FIG. 17, the same components as those in FIG.

  As illustrated in FIG. 17, the network includes a plurality of mesh access points 10 (MAPs 10a to 10f), a single GW 20c, and a control device 30. The GW 20c has a function corresponding to SDM / SDMA, and can establish a radio link different from the MAP 10a and the MAP 10d and can perform communication simultaneously with the MAP 10a and the MAP 10d.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. In the following, differences between the first embodiment and the fourth embodiment described above will be mainly described.

  Specifically, in the first embodiment described above, the description after changing the combination of the MAPs 10 that establish a wireless link and rewriting the routing information (route information) has not been mentioned. On the other hand, in the fourth embodiment, when a plurality of terminals communicate without going through the GW 20, the MAP 10 is changed after rewriting the routing information (route information) by changing the combination of the MAPs 10 that establish a wireless link. The route between the terminals that establish a wireless link is also changed.

(Example of route selection)
Hereinafter, an example of route selection according to the fourth embodiment of the present invention will be described with reference to the drawings. FIG. 18 is a diagram showing an example of route selection according to the fourth embodiment of the present invention.

  As shown in FIG. 18A, the path between the terminal 50a and the terminal 50b is a path via the MAP 10c and the MAP 10b. In this state, if the radio link extending from the MAP 10c to the MAP 10b interferes with other radio links, as shown in the first embodiment, the MAP 10c controls the directivity of the radio wave transmitted by the MAP 10c. There is a case where the MAP 10 that is the link partner is changed to the MAP 10a.

  Here, when the routing information of the MAP 10c is rewritten so that the MAP 10c establishes a radio link with the MAP 10a, the route between the terminal 50a and the terminal 50b is changed to a route via the MAP 10c, the MAP 10a, and the MAP 10b. That is, when the terminal 50a and the terminal 50b perform communication without going through the GW 20, if the routing information of the MAP 10c is rewritten, interference occurring in the wireless mesh network is reduced, but between the terminal 50a and the terminal 50b. The number of hops increases.

  Accordingly, as shown in FIG. 18, in order to reduce the number of hops between the terminal 50a and the terminal 50b, the MAP 10 with which the terminal 50b is to establish a wireless link is changed. Specifically, the MAP 10 with which the terminal 50b establishes a wireless link is changed from the MAP 10b to the MAP 10a.

(Function and effect)
According to the terminal 50 according to the fourth embodiment of the present invention, when the terminal 50a and the terminal 50b communicate with each other without going through the GW 20, each terminal 50 has changed after the combination of the MAPs 10 that establish the radio link is changed. The route between the terminals 50 is also changed. Therefore, it is possible to effectively reduce interference occurring in the wireless mesh network while suppressing an increase in the number of hops between the terminals 50.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the first embodiment described above, the control device 30 controls the directivity of the radio wave transmitted by the MAP 10, the combination (route information) of the MAP 10 that establishes a radio link, the transmission power of the radio wave that the MAP 10 transmits, and the radio link that the MAP 10 extends. However, the present invention is not limited to this.

  Specifically, the control device 30 may determine parameters only for the directivity of the radio wave transmitted by the MAP 10 and the combination (route information) of the MAP 10 that establishes a wireless link, and only for the transmission power of the radio wave transmitted by the MAP 10. The parameter may be determined.

  Similarly, in the second embodiment described above, the MAP 10 transmits the directivity of the radio wave transmitted by the own MAP 10, the other MAP 10 (route information) with which the MAP 10 establishes a wireless link, and the transmission of the radio wave transmitted by the own MAP 10. The parameters are determined for the power and the transmission rate of the wireless link established by the own MAP 10, but the present invention is not limited to this.

  Specifically, the MAP 10 may determine parameters only for the directivity of the radio wave transmitted by the own MAP 10 and the other MAP 10 (route information) to which the own MAP 10 establishes a wireless link. The parameter may be determined only for the transmission power of the radio wave.

  In the first embodiment described above, the network information management unit 32 of the control device 30 preliminarily manages the topology of the wireless mesh network (identifier and position of the MAP 10 configuring the wireless mesh network) as network information. However, the present invention is not limited to this. For example, the network information management unit 32 of the control device 30 may construct the topology of the wireless mesh network based on information indicating the arrival direction of the radio wave received by each MAP 10 from another MAP 10.

  Furthermore, in the first embodiment and the second embodiment described above, the MAP 10 gives a packet when a packet loss caused by interference received from a radio link (interfering link) extended by another MAP 10 exceeds a predetermined threshold. Although a message indicating that interference has been received by the interference link (a parameter change message for requesting suppression of interference by the interfering link) is transmitted, the present invention is not limited to this.

  Specifically, when the interference power of a radio link (interfering link) extended by another MAP 10 exceeds a predetermined threshold, the MAP 10 indicates a message indicating that the interference from the interfering link has been received (by the interfering link). A parameter change message for requesting interference suppression may be transmitted.

  In the second embodiment described above, the MAP 10 that is an interfering access point determines a parameter to be set in the own MAP 10, but the present invention is not limited to this.

  Specifically, the MAP 10 that is the interfered access point may determine a parameter to be set in the MAP 10 that is the interfering access point, and notify the determined parameter to the MAP 10 that is the interfering access point. For example, the MAP 10 that is the interfered access point determines the parameter of the transmission power of the radio wave transmitted by the MAP 10 that is the interfered access point so that the received power of the interfered link is equal to or less than a predetermined threshold.

It is a figure which shows the structure of the network which concerns on 1st Embodiment of this invention. It is a figure which shows the concept of the control by the control apparatus 30 which concerns on 1st Embodiment of this invention (the 1). It is a figure which shows the concept of the control by the control apparatus 30 which concerns on 1st Embodiment of this invention (the 2). It is a figure which shows the concept of the control by the control apparatus 30 which concerns on 1st Embodiment of this invention (the 3). It is a block diagram which shows the structure of the control apparatus 30 which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of MAP10 which concerns on 1st Embodiment of this invention. It is a figure which shows the calculation method of the capacity | capacitance of the wireless mesh network which concerns on 1st Embodiment of this invention (the 1). It is a figure which shows the calculation method of the capacity | capacitance of the wireless mesh network which concerns on 1st Embodiment of this invention (the 2). It is a figure which shows the calculation method of the capacity | capacitance of the wireless mesh network which concerns on 1st Embodiment of this invention (the 3). It is a figure which shows the calculation method of the capacity | capacitance of the wireless mesh network which concerns on 1st Embodiment of this invention (the 4). It is a figure which shows the calculation method of the capacity | capacitance of the wireless mesh network which concerns on 1st Embodiment of this invention (the 5). It is a figure which shows the calculation method of the capacity | capacitance of the wireless mesh network which concerns on 1st Embodiment of this invention (the 6). It is a flowchart which shows operation | movement of the control apparatus 30 which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of MAP10 which concerns on 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of MAP10 which concerns on 2nd Embodiment of this invention (the 1). It is a flowchart which shows operation | movement of MAP10 which concerns on 2nd Embodiment of this invention (the 2). It is a figure which shows the structure of the network which concerns on 3rd Embodiment of this invention. It is a figure which shows an example of the route selection which concerns on 4th Embodiment of this invention.

Explanation of symbols

  MAP 10, antenna 11, communication unit 12, message processing unit 13, parameter determination unit 13b, directivity control unit 14, transmission power control unit 15, transmission rate control unit 16, routing information storage unit 17, interference detection unit 18, message generation Unit 19, GW 20, control device 30, communication unit 31, network information management unit 32, parameter determination unit 33, capacity comparison unit 34, message generation unit 35, LAN 40, terminal 50

Claims (7)

  1. A control device that manages a plurality of wireless access points that establish a wireless link in a wireless mesh network that includes a plurality of wireless links,
    An interfering link information acquisition unit that acquires interfering link information indicating that an interfering link that is one of the radio links interferes with an interfered link that is one of the radio links;
    A setting determination unit that determines the setting of the radio link based on the interference link information acquired by the interference link information acquisition unit;
    A setting notification unit that notifies the interference access point that is the wireless access point that establishes the interference link, the setting of the wireless link determined by the setting determination unit;
    The pre-determination capacity that is the capacity of the wireless mesh network corresponding to the radio link setting that has been set before the setting of the radio link is determined by the setting determination unit, and the determination that has been determined by the setting determination unit A network capacity comparison unit that compares a determined capacity that is a capacity of the wireless mesh network corresponding to a wireless link setting ;
    The network capacity comparison unit calculates an average reception success bit number and required time of each flow in which a packet is transmitted, calculates a total capacity of a domain including the plurality of wireless access points, and a plurality of the domains To calculate the post-determined capacity of the wireless mesh network,
    The setting notification unit notifies the interfering access point of the setting of the radio link determined by the setting determination unit when the determined capacity is larger than the pre-determination capacity. .
  2.   The setting determination unit determines directivity of a radio wave transmitted by the interfering access point and the wireless access point at which the interfering access point extends the wireless link as a setting of the wireless link. The control apparatus according to 1.
  3.   The control apparatus according to claim 1, wherein the setting determination unit determines transmission power of a radio wave transmitted by the interfering access point as a setting of the wireless link.
  4. The control apparatus according to claim 1 , wherein the network capacity comparison unit calculates the capacity of the wireless mesh network in consideration of an influence of a hidden terminal problem according to a configuration of the wireless mesh network.
  5.   2. The control apparatus according to claim 1, wherein when the number of the radio links is N and the maximum number of retransmissions is R, the number of patterns of the flow is represented by the following expression.
  6.   P is the communication success probability of wireless link i. i And r is the number of retransmissions in the radio link i, and t is the time required for communication in the radio link i. i, r And the time required for the communication of the flow pattern j is T j And the occurrence probability of the pattern j is P j If
      6. The average number of successful reception bits (Lf) of the flow f and the required time (Tf) relating to the flow f are expressed by the following formula, and J is the number of patterns of the flow: The control device described in 1.
  7.   The total capacity of the domain including the flow f is expressed by the following equation, where α is an adjustment factor that adjusts the influence of the hidden terminal problem or the exposed terminal problem, and F is the number of the flows. The control device according to claim 6.
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