JP4808202B2 - Wireless communication system control method and wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system control method and a wireless communication system, and more particularly to a technique for setting a routing table for multihop communication.

  For example, Patent Document 1 includes a plurality of wireless terminals that perform wireless data communication, and each of the wireless terminals communicates with all other wireless terminals directly or through one or more other wireless terminals. A hop wireless communication network is described.

  In Patent Document 2, in a multi-hop wireless network used for a wireless sensor network or the like that transfers data from a wireless terminal to a wireless terminal in a bucket-relay manner, traffic change due to increase or decrease in data amount or change in data type, wireless A technique is described in which the intermittent reception cycle and the preamble length of data between wireless terminals are changed in accordance with changes in network topology due to addition / deletion of terminals.

In Patent Document 3, in order to grasp the positional relationship between nodes in a wireless multi-hop network, each node needs to hold a route information table having a size proportional to the total number of nodes in the network. In order to prevent the need for storage capacity, when data is transmitted from one node to all nodes, it is clearly duplicated reception using the routing information table held by each node and the routing control information of the received packet It is described that data is relayed and transmitted to an adjacent node by autonomously judging.
JP 2005-229445 A JP 2005-217548 A JP 2007-104320 A

  By the way, in the multi-hop communication, there is no particular limitation on the number of stages of node stations to be relayed. However, since there is a transmission delay and a reduction in transmission capacity, it is actually possible to hop only up to about five stages.

  Here, in order to expand the communication range while suppressing the number of hops, for example, it is conceivable to adopt a multicast system for multi-hop communication, but it is not possible to communicate with a terminal at a long distance. Also, in the multicast method, destination information must be added to data, and the header size increases and the data transmission capacity (payload) decreases.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a wireless communication system control method and a wireless communication system capable of expanding the range in which multi-hop communication is possible.

In order to achieve the above object, one aspect of the present invention is a control method of a wireless communication system including a plurality of node stations that perform multi-hop communication, wherein the node stations are connected to other node stations. The node station transmits the result of the RSSI test to a control station that is one of the node stations, and the control station performs the other of the result of the RSSI test performed by itself. The RSSI test result received from the node station is stored, the control station groups the node stations other than the control station into a plurality of groups based on the RSSI test result, and the control station Based on the result of the RSSI test, a first node station capable of directly communicating with the control station is detected for each group, and the first node station cannot be directly communicated with the control station. Detecting a second node station capable of indirect communication, and generating a routing table for setting a route for communication between the control station and the first or second node station based on the detected results, The control station transmits the routing table to another node station, and the other node station receives and stores the routing table.

Further , one aspect of the present invention is a control method of the wireless communication system, wherein the control station selects a plurality of node stations in descending order of received electric field strength with the control station based on the result of the RSSI test. The grouping is performed based on the routing information held by the selected node station.

Also , one aspect of the present invention is a method of controlling a wireless communication system including a plurality of node stations that perform multi-hop communication, and the node station performs an RSSI test with another node station. The node station transmits the result of the RSSI test to the control station that is one of the node stations, and the control station receives the result of the RSSI test performed by itself and the other node station. The RSSI test result is stored, the node station performs a direction detection test on the other node stations, and the node station controls the result of the direction detection test as one of the node stations. The control station stores the result of the direction detection test performed by itself and the result of the direction detection test received from another node station, and the control station stores the result of the RSSI test and the direction detection. Based on test results , Grouping node stations other than the control station into a plurality of groups, and the control station determines a first node station that can directly communicate with the control station for each group based on the result of the RSSI test. And detecting a second node station that cannot directly communicate with the control station but is capable of indirect communication via the first node station, and based on the detected results, the control station and the first node are detected. Alternatively, a routing table for setting a route for communication with the second node station is generated, the control station transmits the routing table to another node station, and the other node station receives the routing table. And memorize it.
Also , one aspect of the present invention is a control method of the wireless communication system, wherein the control station groups the other node stations according to an angle range viewed from the control station based on a result of the direction detection test. And

One aspect of the present invention is a wireless communication system including a plurality of node stations that perform multi-hop communication, wherein the node station performs an RSSI test with another node station. The node station transmits the result of the RSSI test to a control station that is one of the node stations, and the control station receives the result of the RSSI test performed by itself and the other node stations. Means for storing the received RSSI test results, means for the control station to group the node stations other than the control station into a plurality of groups based on the results of the RSSI test, and the control station comprises the RSSI Based on the result of the test, for each group, the first node station that can directly communicate with the control station is detected, and the first node station cannot be directly communicated with the control station. And detecting a second node station capable of indirect communication, and generating a routing table for setting a route for communication between the control station and the first or second node station based on the detected results And the control station comprises means for transmitting the routing table to another node station, and means for receiving and storing the routing table by the other node station.

One aspect of the present invention is a wireless communication system including a plurality of node stations that perform multi-hop communication, wherein the node station performs an RSSI test with another node station. The node station transmits the result of the RSSI test to a control station that is one of the node stations, and the control station receives the result of the RSSI test performed by itself and the other node stations. Means for storing the received RSSI test results; means for the node station to perform a direction detection test on the other node stations; and Means for transmitting to one control station, and the control station stores a result of a direction detection test performed by itself and a result of a direction detection test received from another node station, and the control station stores the RSSI Test results and previous Based on the result of the direction detection test, a means for grouping node stations other than the control station into a plurality of groups, and the control station, for each group based on the result of the RSSI test, Detect a first node station capable of direct communication and detect a second node station that cannot communicate directly with the control station but is capable of indirect communication via the first node station. Means for generating a routing table for setting a route for communication between the control station and the first or second node station based on the result, and the control station transmits the routing table to another node station. Means and means for receiving and storing the routing table in the other node station.

  According to the present invention, the range in which multi-hop communication is possible can be expanded.

  FIG. 1 shows a configuration of a wireless communication system 1 described as an embodiment of the present invention. As shown in the figure, the wireless communication system 1 includes a plurality of node stations 200. One of the node stations 200 is a node station 200 (hereinafter referred to as a node station 200A) that functions as a control station that manages routing information of the wireless communication system 1, and the other is managed by the node station 200A. Node station 200 (hereinafter referred to as node station 200B). In this wireless communication system 1, each node station 200 forms an ad hoc network that is an autonomous distributed network.

  The hardware configuration of the node station 200 is shown in FIG. The node station 200 includes a CPU 211, a memory 212, a wireless communication interface 213, an RSSI circuit 214 (RSSI: Radio Signal Strength Indicator), an antenna group 215, and an antenna selector switch 216. Among these, the CPU 211 executes programs stored in the memory 212 to realize various functions provided in the node station 200.

  The wireless communication interface 213 is a wireless communication module (RF unit (Radio Frequency)) compliant with, for example, a wireless LAN (Local Area Network) communication standard (CSMA / CA) or a ZigBee (registered trademark) communication standard. Wireless communication is performed with another node station 200 according to a wireless communication protocol such as (Wireless Access Protocol).

  The wireless communication interface 213 configures an ad hoc network by exchanging routing information with other node stations 200. As a communication protocol of an ad hoc network, for example, Hi-TORA (Hierarchy-Temporally Ordered Routing Algorithm), Hi-AODV (Hierarchy-Ad Hoc On-Demand Distance Vector Routing), Hi-DSR (Hierarchy-Dynamic Source Routing), etc. are used. It is done. These communication protocols are described in, for example, “Yoshiaki Kakuda, 1 other person,“ Autonomous distributed clustering and hierarchical routing of ad hoc networks ”, April 26, 2004, 17th Circuit and System, Karuizawa Workshop”. Has been.

  The RSSI circuit 214 measures the received electric field strength of communication performed by the wireless communication interface 214 and transmits the measured value to the CPU 211. The antenna group 215 includes a plurality of circularly polarized directional antennas (hereinafter referred to as antennas). The antenna changeover switch 216 selects any one of the antennas constituting the antenna group 215 and connects to the wireless communication interface 213.

  The bus 220 connects the CPU 211, the memory 212, the wireless communication interface 213, the RSSI circuit 214, the antenna group 215, and the antenna selector switch 216 described above so that they can communicate with each other.

  FIG. 3A shows functions of the node station 200A. The wireless communication unit 261 performs processing related to communication with other node stations 200. The RSSI test execution unit 262 performs an RSSI test with another node station 200. The direction detection test execution unit 263 transmits a radio signal (hereinafter referred to as an orientation signal) for locating the position, moving direction, and the like of the node station 200B. Details of orientation and orientation signals will be described later. The grouping processing unit 264 performs grouping of node stations 200 described later. The routing processing unit 265 performs setting of a routing table in ad hoc communication and transmission / reception of the routing table with other node stations 200.

  FIG. 3B shows a schematic function of the node station 200B. The wireless communication unit 271 performs processing related to communication performed with another node station 200. The RSSI test execution unit 272 performs an RSSI test with another node station 200. The routing processing unit 275 transmits and receives a routing table in ad hoc communication with the other node stations 200.

  Next, the direction detection function provided in the wireless communication system 1 will be described. The radio communication interface 213 of the node station 200A transmits the orientation signal while periodically switching a plurality of antennas constituting the antenna group 215. In addition, the direction detection test execution unit 273 of the node station 200B receives the orientation signal transmitted from the node station 200A. The node station 200 </ b> A transmits a synchronization signal to other node stations 200 in order to avoid radio wave interference of the orientation signals transmitted from each node station 200, so that the orientation signals transmitted from each node station 200 are transmitted. To prevent interference.

  FIG. 4 shows the data format of the orientation signal. In the figure, the synchronization signal 411 is composed of a total of 48 bits including a 32-bit preamble signal and a 16-bit synchronization signal. The location code 412 (UCODE) is information for specifying the installation location of the control station 200, and is composed of a 128-bit code assigned to each location according to the unified standard. The antenna information 413 includes 16-bit data including information indicating the antenna height, the antenna identifier, and the antenna directivity direction. The measurement signal 414 includes signals for detecting the direction of the other node station 200B with respect to the node station 200A and the relative distance between the node station 200A and the node station 200B, and sequentially switches the four antennas constituting the antenna group 215. The 2048 chip spreading code is transmitted.

  Next, the positional relationship between the two node stations 200 (1) and 200 (2) will be described with reference to FIG. As shown in the figure, the antenna group 215 of the node station 200 (1) has a substantially square shape with an interval of 3 cm (this interval corresponds to a quarter wavelength when a radio wave in the 2.4 GHz band is used as the orientation signal). And four circularly polarized directional antennas 2151 arranged adjacent to each other.

In the figure, the angle α formed between the horizontal direction at the height of the antenna group 215 and the direction of the node station 200 (2) with respect to the antenna group 215 is
α = arcTan (D (m) / L (m)) = arcSin (ΔL (cm) / 3 (cm))
It is.

  In the figure, ΔL (cm) is a propagation path length difference between two specific antennas 2151 constituting the antenna group 215 and the node station 200B.

  Here, if the phase difference between the orientation signals transmitted from two specific antennas 2151 constituting the antenna group 215 is Δθ, there is a relationship of ΔL (cm) = Δθ / 2π / λ (cm). For example, when a 2.4 GHz band radio wave is used as the orientation signal, since λ≈12 (cm), α = arcSin (2Δθ / π). Therefore, in the measurable range (−π / 2 <Δθ <π / 2), α = Δθ (radian), thereby detecting the direction of the node station (2) with respect to the node station 200 (1).

  The direction detection mechanism described above is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2004-184078, 2005-351877, 2005-351878, and 2006-23261.

  Next, update processing of a routing table held in each node station 200, which is performed when the node station 200 moves, when a node station 200 is newly added to or removed from the wireless communication system 1, etc. Will be described.

  FIG. 6A and FIG. 6B are flowcharts for explaining processing related to the update of the routing table performed in the wireless communication system 1.

  As shown in FIG. 6A, first, the node station 200A transmits an instruction to perform an RSSI test for all the node stations 200 to each node station 200B (S611). Each node station 200 (200A and 200B) performs an RSSI test on all the opposing node stations 200 (S612). Note that the communication at this time is performed by direct communication between the node stations 200, and this execution instruction is performed, for example, by broadcast transmission of a hello packet from the node station 200A to the node station 200B.

  Next, each node station 200 (200A and 200B) saves (stores) the RSSI test result, and each node station 200B transmits the RSSI test result to the node station 200A (S613). Note that the communication at this time is performed by direct communication between the node stations 200.

  Upon receiving the RSSI test result sent from each node station 200B, the node station 200A stores this (S614). An example of the RSSI test result stored in the node station 200A at this time is shown in FIG.

  Next, the node station 200A sorts the node stations 200 facing each node station 200 in descending order of the received electric field strength for each node station 200 (S615).

  Next, the node station 200A extracts, for each node station 200, another node station 200 having a received electric field strength that can communicate with the node station 200 (S616). Then, the node station 200A transmits information indicating the n node nodes 200 having the highest received electric field strength to each node station 200B, and instructs each node station 200B to execute a direction detection test for the other node stations 200. Transmit (S617). Note that the communication at this time is performed by direct communication between the node stations 200.

  Next, the node station 200A and each node station 200B perform a direction detection test on the top n other node stations 200 (S618). Each node station 200 stores the result of the direction detection test. Each node station 200B transmits the result of the direction detection test to the node station 200A (S619). Note that the communication at this time is performed by direct communication between the node stations 200.

  The node station 200A receives and stores the result of the direction detection test transmitted from the node station 200B (S620). An example of the direction detection test result stored by the node station 200A at this time is shown in FIG. In this example, the north direction from the node station 200A is 0 degree, the east direction is 90 degrees, the south is 180 degrees, and the west direction is 270 degrees.

  Next, based on the result of the direction detection test, the node station 200A performs grouping for each node station 200B existing in a direction within a predetermined angle with the node station 200A as a reference (S621). For example, when the number of groups to be divided is two and the predetermined angle is 180 degrees, in the example of FIG. 8, the groups of the node stations 200B (1) to (5) and the node stations 200B (6) to (9) Grouped into two groups.

  In S651 of FIG. 6B, the node station 200A determines, for each group, whether there are a plurality of node stations 200B that can communicate with the node station 200A in each group. Whether or not communication is possible is determined by comparing the received electric field strength of the RSSI test result with a predetermined threshold (for example, −85 dBm). If there are a plurality (S651: YES), the process proceeds to S652. If it does not exist (S651: NO), the process proceeds to S654. In S654, 1 is set in the variable a, and then the process proceeds to S655.

  In S652, the node station 200A counts the group in which there are a plurality of node stations 200B capable of communicating with the node station 200A from the node station 200B having the largest received electric field strength with the node station 200A in descending order of strength a + 1 ( a = 1, 2, 3, 4, 5) It is determined whether or not multihop communication is possible with the 200th node station 200B.

  If communication is possible (S653: YES), the variable a is incremented in S653, and the process returns to S652. On the other hand, if communication is not possible (S653: NO), the process proceeds to S655.

  In S655, the node station 200A communicates with the a-th node station 200B in each group that can communicate with the node station 200A (that is, a route that skips the a-1 node stations 200B). Create (or update) its own routing table (as set).

  For example, in the example of the RSSI test result of FIG. 7, for the group of node stations 200B (1) to (5), the node station B (1) to node station 200B (4) (first node station) is the node station 200A. However, the node station 200B (5) cannot communicate directly. On the other hand, the node station 200B (5) (second node station) can indirectly communicate with the node station 200A via the node station 200B (1) which is the first node station.

  As described above, in this case, the node station 200A is configured such that the node station 200A → the node station 200B (1) → the node station 200B (5), the node station 200A → the node station 200B (2), and the node station 200A → the node station 200B (3). Then, a routing table to be set for the route of the node station 200A → the node station 200B (4) is generated (or updated to the contents).

  The node station 200A transmits the updated routing table (or update difference) to the node station 200B (S656). Note that the communication at this time is performed by direct communication between the node stations 200.

  When the node station 200B receives the routing table (or update difference), the node station 200B updates the routing table held by itself (S657).

  An example of the routing table generated in S655 is shown in FIG. This routing table communicates directly between the node station 200A and the node stations 200B (1) to (9) other than the node station 200B (5), and the node station 200A and the node station 200B (5) It defines that communication is performed via the station 200B (1).

  In the above description, the node stations 200B are grouped according to the angle range as viewed from the node station 200A. However, the grouping method is not limited to this method. For example, a plurality of representative node stations 200B may be selected in descending order of the received electric field strength with the node station 200A, and grouping may be performed based on the routing information held by each selected node station 200B ( For example, routing partners with a predetermined received electric field strength or higher are classified into the same group).

  According to the above, the node station 200A determines whether or not multihop communication is possible with the node station 200B having the maximum received electric field strength with the node station 200A, and sets a route determined to be capable of multihop communication. Generate a routing table. Then, routing is performed using this routing table.

  Therefore, the node station 200A skips the node station 200B adjacent to the node station 200A and establishes a route for communicating with the other node station 200B, and communicates with the node station 200B with a smaller number of hops than before. The node station 200 </ b> A can communicate with the node station 200 </ b> B that exists at a farther position, and the communicable range can be expanded compared to the conventional case.

  Further, the node station 200A selects a plurality of representative node stations 200B in descending order of the received electric field strength with the node station 200A, and the other node stations 200B based on the routing information held by each selected node station 200B. Therefore, the above grouping can be performed easily and appropriately.

  Further, since the node station 200A groups the other node stations 200B according to the angle range viewed from the node station 200A, the grouping can be performed easily and appropriately.

  In addition, the description of the above embodiment is for facilitating understanding of the present invention, and does not limit the present invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

It is a figure which shows the structure of the radio | wireless communications system 1 demonstrated as one Embodiment of this invention. It is the hardware constitutions of the node station 200 demonstrated as one Embodiment of this invention. This is a function of the node station 200A described as an embodiment of the present invention. This is a function of the slave station 200B described as an embodiment of the present invention. It is a figure which shows the data format of the orientation signal transmitted from the control station 200 demonstrated as one Embodiment of this invention. FIG. 3 is a diagram for explaining a positional relationship between two node stations 200. It is a flowchart explaining the update process of a routing table. It is a flowchart explaining the update process of a routing table. It is an example of a RSSI test result. It is an example of a direction detection test result. It is an example of a routing table.

Explanation of symbols

1 wireless communication system 200 node station 211 CPU
212 memory 213 wireless communication interface 215 antenna group 2151 antenna 2152 changeover switch 261 wireless communication unit 262 RSSI test execution unit 263 direction detection test execution unit 264 grouping processing unit 265 routing processing unit

Claims (3)

A method for controlling a wireless communication system including a plurality of node stations that perform multi-hop communication,
The node station performs an RSSI test with the other node stations,
The node station transmits the result of the RSSI test to a control station that is one of the node stations,
The control station stores the results of the RSSI test performed by itself and the RSSI test results received from the other node stations,
The node station performs a direction detection test on the other node stations,
The node station transmits a result of the direction detection test to a control station that is one of the node stations,
The control station stores the result of the direction detection test performed by itself and the result of the direction detection test received from another node station,
The control station groups node stations other than the control station into a plurality of groups based on the result of the RSSI test and the result of the direction detection test,
The control station detects a first node station capable of directly communicating with the control station for each group based on the RSSI test result, and cannot directly communicate with the control station. Routing for detecting a second node station capable of indirect communication via one node station and setting a route for communication between the control station and the first or second node station based on the detected result Generate a table,
The control station transmits the routing table to another node station;
The said other node station receives and memorize | stores the said routing table. The control method of the radio | wireless communications system characterized by the above-mentioned. A control method for a wireless communication system according to claim 1 ,
A control method for a radio communication system, wherein the control station groups the other node stations according to an angle range viewed from the control station based on a result of the direction detection test. A wireless communication system including a plurality of node stations that perform multi-hop communication,
Means for said node station to perform an RSSI test with another said node station;
Means for the node station to transmit the result of the RSSI test to a control station which is one of the node stations;
Means for storing the result of the RSSI test performed by the control station and the RSSI test result received from the other node station;
Means for the node station to perform a direction detection test on the other node stations;
Means for the node station to transmit a result of a direction detection test to a control station which is one of the node stations;
The control station stores the result of the direction detection test performed by itself and the result of the direction detection test received from another node station,
Means for grouping node stations other than the control station into a plurality of groups based on the result of the RSSI test and the result of the direction detection test;
Based on the result of the RSSI test, the control station detects a first node station capable of directly communicating with the control station for each group and cannot directly communicate with the control station. Routing for detecting a second node station capable of indirect communication via one node station and setting a route for communication between the control station and the first or second node station based on the detected result Means for generating a table;
Means for the control station to transmit the routing table to another node station;
The other node station comprises means for receiving and storing the routing table.

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