JP5976234B1 - Frequency allocation apparatus, management apparatus, radio master station, radio terminal, communication system, and frequency allocation method - Google Patents

Abstract

The frequency allocation device 1 according to the present invention allocates different radio frequency bands to an interference relationship determination unit 11 that determines the presence or absence of an interference relationship between cells, and to cells that are determined to have an interference relationship by the interference relationship determination unit 11. And a channel allocating unit 13 that allocates radio frequency bands for each cell so that the number of radio frequency bands used for allocation is minimized and the number of cells to which a specific radio frequency band is allocated is increased.

Description

  The present invention relates to a frequency assignment device, a management device, a wireless master station, a wireless terminal, a communication system, and a frequency assignment method for assigning frequencies to a wireless master station and a wireless terminal.

  In recent years, interest in diversified use of renewable energy and energy-saving society has increased, and the introduction of smart meter systems that enable visualization of power consumption by automatic meter reading and supply and demand control has been promoted. In such a smart meter system, for example, a wireless communication network is configured by adding a wireless terminal having a wireless communication means to an electric power meter arranged in a consumer unit, and an organic communication network such as an electric power company and the like. By connecting them electrically, it is configured to enable automatic metering of power consumption, centralized management and control by an operator, and the like.

  Here, since the wireless terminals are deployed in units of consumers as described above, the installation positions are predetermined and the quantity is enormous. These huge number of fixed wireless terminals are wirelessly connected directly or via other wireless terminals to a wireless master station connected to a backbone communication network such as an electric power company. The wireless master station collects measurement results from the power measurement meter from the subordinate wireless terminals. A smaller number of wireless master stations is desirable from the viewpoints of low resources, low energy, and low cost.

  On the other hand, in wireless communication, mutual interference occurs between devices that perform communication using the same wireless channel, that is, the same frequency band. In a conventional radio channel arrangement method in a radio communication system, the same radio channel is reused in geographically distant cells where interference interference does not occur between cells that are communication areas covered by a radio base station that is a radio master station. To do. The distance that can be reused is called the repeat distance. In general, the minimum basic group capable of repeating the same frequency is called a repetitive pattern, and the number of cells belonging to the repetitive pattern is called a repetitive cell number. The smaller the number of repeated cells, the better the frequency utilization efficiency. For this reason, in the conventional radio channel arrangement method, a repetitive pattern is selected so that the number of repetitive cells can be ensured to be a repetitive distance (see, for example, Non-Patent Documents 1 and 2).

IEICE "Knowledge Base", Group 4, Chapter 3, Chapter 2 <ver.1 / 2011.09.12> (http://www.ieice-hbkb.org/files/04/04gun_03hen_02.pdf) Mobile Communications “Chapter 7 Zone Configuration and Access Control” Nobuo Shinji Maruzen Co., Ltd., issued September 30, 1989

  As described above, in the conventional radio channel arrangement method, the radio master station is arranged based on the selected repetition pattern in order to realize the radio channel arrangement by selecting the repetition pattern on the premise of cell repetition. On the other hand, for example, when configuring a wireless network with a group of wireless terminals that are fixedly disposed as in the smart meter system described above, the number of wireless master stations that constitute a cell is minimized based on the layout of the wireless terminal group. It is desirable to do.

  However, the above-described conventional radio channel arrangement method has a problem that the radio master station must be arranged based on the repetition pattern, and the degree of freedom of arrangement of the radio master station and channel assignment is small. Also in mobile communication, it is desirable to increase the degree of freedom of base station placement and channel assignment, compared to the conventional radio channel placement method based on a repetitive pattern, for example, when it is desired to make use of the existing base station placement.

  The present invention has been made in view of the above, and an object of the present invention is to provide a frequency allocation device that can perform channel allocation without depending on a repetitive pattern.

In order to solve the above-described problems and achieve the object, the frequency allocation device of the present invention includes an interference relationship determination unit that determines the presence or absence of an interference relationship between cells. In addition, the frequency allocation device of the present invention allocates different radio frequency bands to cells determined to be in an interference relationship by the interference relationship determination unit, minimizes the number of radio frequency bands used for allocation, and performs a specific radio A frequency allocation unit that allocates a radio frequency band for each cell so that the number of cells to which the frequency band is allocated increases, and the interference relationship determination unit compares the inter-cell distance with the interference determination threshold It determines the presence of interference relationship between the interference determination threshold value, Ru is calculated based on the traffic volume.

  The frequency allocation device according to the present invention has an effect that channel allocation can be performed without depending on a repetition pattern. For this reason, compared with the conventional radio channel arrangement method based on a repetitive pattern, it is possible to increase the degree of freedom of arrangement of radio master stations and channel assignment. Further, since the radio master stations can be arranged so as to reduce the number of radio master stations as compared with the radio channel arrangement method based on the repetitive pattern, it is possible to reduce resources, energy, and cost.

The figure which shows the structural example of the communication system concerning Embodiment 1. FIG. The figure which shows the structural example of the radio | wireless master station of Embodiment 1. FIG. 3 illustrates a configuration example of a wireless terminal according to the first embodiment. FIG. 10 is a diagram illustrating another configuration example of the wireless terminal according to the first embodiment. The figure which shows the structural example of the smart meter of Embodiment 1. FIG. The figure which shows the structural example of the frequency allocation apparatus of Embodiment 1. FIG. The figure which shows the structural example of the computer system by which the frequency allocation apparatus of Embodiment 1 is mounted. The figure which shows the structural example of the management server of Embodiment 1. FIG. The figure which shows an example of the cell which the radio | wireless terminal of the radio | wireless master station of Embodiment 1 and the radio | wireless master station directly or indirectly radio-connects comprises The figure which shows the traffic density in the cell of Embodiment 1 typically The figure which shows the traffic density of the two cells of Embodiment 1 typically The figure which shows an example of the determination result of the presence or absence of the interference relationship between the cells of Embodiment 1. The flowchart which shows an example of the determination processing procedure of the presence or absence of interference relation in the frequency allocation apparatus of Embodiment 1. The figure which shows the structural example of the interference related information of Embodiment 1. FIG. Flowchart illustrating an example of a radio channel arrangement procedure in the interference-related cell group according to the first embodiment The figure which shows an example of the radio | wireless channel arrangement | positioning result of Embodiment 1. Flowchart illustrating an example of radio channel arrangement and setting processing procedure according to the second embodiment The figure which shows the structural example of the communication system concerning Embodiment 3. FIG. The figure which shows the definition of the cell in Embodiment 3.

  Hereinafter, a frequency allocation device, a management device, a wireless master station, a wireless terminal, a communication system, and a frequency allocation method according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of a communication system according to the first embodiment of the present invention. The communication system according to the present embodiment includes wireless terminals 5-1 to 5-M that perform wireless communication with the wireless master station 4-1 directly or via other wireless terminals, and directly or with the wireless parent station 4-2. A wireless terminal 5-101 to 5-L that performs wireless communication via the wireless terminal; a management server 2 that is a management device connected to the wireless master stations 4-1 and 4-2 via the backbone communication network 3; And a frequency allocation device 1 that is connected to the management server 2 and determines radio channels to be allocated to the radio master stations 4-1 and 4-2, that is, radio frequency bands. Note that M is an integer greater than or equal to 1 and less than or equal to 100, and L is an integer greater than or equal to 101. The wireless master station 4-1 and the wireless terminals 5-1 to 5 -M that perform wireless communication with the wireless master station 4-1 directly or via other wireless terminals constitute the cell 6-1 and wirelessly The radio terminals 5-101 to 5-L that perform radio communication with the master station 4-2 and the radio master station 4-2 directly or via other radio terminals constitute a cell 6-2. The definition of the cell according to the present embodiment will be described later.

  In FIG. 1, for simplification, the number of wireless terminals directly or indirectly connected to the wireless master station 4-1 is 100 or less, and the wireless terminals 5-101 and later are directly or Although an example of indirect connection is shown, the number of wireless terminals is not limited to 100 or less. Further, FIG. 1 shows an example in which both a wireless terminal that is indirectly wirelessly connected to the wireless master station and a wireless terminal that is directly wirelessly connected to the wireless master station are shown. There may be no wireless terminal to be connected. The correspondence between the wireless master stations 4-1 and 4-2 and the wireless terminals that are directly or indirectly wirelessly connected can be changed.

  Although FIG. 1 shows an example in which the management server 2 and the frequency allocation device 1 are connected, the frequency allocation device 1 may not be connected to the management server 2. The backbone communication network 3 may be a wired network or a wireless network. In FIG. 1, two wireless master stations are shown, but the number of wireless master stations is not limited to two and may be any number.

  When the frequency allocation device 1 determines the radio channel to be allocated to the radio master stations 4-1 and 4-2, the frequency allocation device 1 transmits the determination result to the management server 2 as channel arrangement information. Alternatively, the channel arrangement information may be input to the management server 2 using an electronic medium, a paper medium, or the like by the administrator or operator of the communication system. That is, it may be transferred from the frequency allocation device 1 to the management server 2 offline. Based on the channel arrangement information, the management server 2 notifies the radio master stations 4-1 and 4-2 of the channels used by the radio master stations 4-1 and 4-2, that is, assigned channels. At this time, the change timing for changing the radio channel operated together with the assigned channel to the assigned channel may be notified.

  FIG. 2 is a diagram illustrating a configuration example of the wireless master station 4 which is the master station apparatus according to the present embodiment. The configurations of the wireless master stations 4-1 and 4-2 of the present embodiment are common. Hereinafter, when the wireless master stations 4-1 and 4-2 are shown without being distinguished, they are appropriately referred to as the wireless master station 4. The wireless master station 4 includes an antenna 40, a wireless communication processing unit 41 that performs a reception process on a signal received by the antenna 40 and a transmission process on a signal transmitted from the antenna 40, and a path construction process and a wireless communication processing unit described later. A control unit 42 that performs control processing including processing for setting 41 wireless channels, a backbone NW (Network) communication processing unit 43 that performs communication processing for connecting to the backbone communication network 3, and a storage unit 44. Prepare.

  The control unit 42 is, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like. The storage unit 44 is used for storing data and the like used by the control unit 42 for processing. When each function performed by the control unit 42 is provided as software, the storage unit 44 stores a program for the control unit 42 to execute each function, and this program is executed by the control unit 42. Accordingly, the control unit 42 may realize each function.

  The wireless communication processing unit 41 is configured to be able to operate with a plurality of wireless channels, and the operating wireless channel is instructed from the control unit 42. Based on the assigned channel notified from the management server 2, the control unit 42 instructs the wireless communication processing unit 41 to operate the wireless channel. In the initial state, that is, the state in which the allocation channel is not notified from the management server 2, the wireless communication processing unit 41 operates on a predetermined wireless channel. In addition, the storage unit 44 is configured to be able to hold a radio channel number of a radio channel operated in the own station, a radio channel change timing, and the like.

  In addition, the control unit 42 generates a channel setting instruction storing the assigned channel to the wireless terminal, and outputs the channel setting instruction to the wireless communication processing unit 41. The wireless communication processing unit 41 notifies a channel setting instruction to a wireless terminal connected directly or indirectly to the local station. At this time, the channel setting instruction is notified of the change timing for changing the radio channel operated together with the assigned channel to the assigned channel.

  FIG. 3 is a diagram illustrating a configuration example of the wireless terminal 5 according to the present embodiment. The configuration of radio terminals 5-1 to 5-M and 5-101 to 5-L in the present embodiment is common. Hereinafter, when the wireless terminals 5-1 to 5-M and 5-101 to 5-L are shown without being distinguished, they are appropriately referred to as wireless terminals 5. The wireless terminal 5 includes an antenna 50, a wireless communication processing unit 51 that performs a reception process for a signal received by the antenna 50 and a transmission process for a signal transmitted from the antenna 50, and a path construction process and a wireless communication processing unit 51 described later. The control part 52 which performs the control process including the process which sets the wireless channel of this, and the memory | storage part 53 are provided.

  The control unit 52 is, for example, a CPU or MPU. The storage unit 53 is used to store data used by the control unit 52 for processing. When each function performed by the control unit 52 is provided as software, the storage unit 53 stores a program for the control unit 52 to execute each function, and the program is executed by the control unit 52. Accordingly, the control unit 52 may realize each function.

  The wireless communication processing unit 51 is configured to be able to operate on a plurality of wireless channels, and the control unit 52 instructs the operating wireless channel. The control unit 52 instructs the radio communication processing unit 51 on the radio channel to operate based on the radio channel setting instruction notified from the radio master station 4. In the initial state, that is, in the state where the wireless channel setting instruction is not notified from the wireless master station 4, the wireless communication processing unit 51 operates on the same wireless channel as the wireless master station 4. In addition, the storage unit 53 is configured to be able to hold a radio channel number of a radio channel operated in the own terminal, a radio channel change timing, and the like.

  Further, when the wireless terminal 5 is connected to another device such as a personal computer, a power meter, a water meter, and a gas meter, the configuration shown in FIG. 4 may be used. In the configuration example illustrated in FIG. 4, the wireless terminal 5 performs connected device communication that performs communication processing with a connected device in addition to the antenna 50, the wireless communication processing unit 51, the control unit 52, and the storage unit 53 illustrated in FIG. 3. A processing unit 54 is provided.

  Any method may be used as a method of notifying the radio channel setting instruction from the radio master station 4 to the radio terminal 5, but the radio master station 4 may change the operation channel of its own station, for example, Then, the information including the signal indicating the radio channel to be changed is notified to the notification signal for notifying the address information of the own station. The control unit 52 of the wireless terminal 5 that has received the notification signal can set the same wireless channel as the wireless channel that the wireless master station 4 changes the operation channel. Thereby, the radio terminal 5 under the radio master station 4 can communicate using the same radio channel as the operation channel set in the radio master station 4.

  In the present embodiment, it is assumed that the wireless master station 4 and the wireless terminal 5 perform transmission avoiding collision of wireless signals by a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method. However, the multiple radio access scheme of the radio master station 4 and the radio terminal 5 is not limited to the CSMA / CA scheme, and may be a TDMA (Time Division Multiple Access) scheme or the like. In the case of the TDMA system, for example, the radio master station 4 may assign a transmission time zone to the subordinate radio terminal 5 or the management server 2 may assign the transmission time zone to the radio master station 4 and the radio terminal 5 at once. Good.

  The communication system of the present embodiment is applied to, for example, a smart meter system. When applied to a smart meter system, the wireless terminal 5 constitutes a device called a smart meter together with a power measurement meter. FIG. 5 is a diagram illustrating a configuration example of a smart meter. As illustrated in FIG. 5, the smart meter 7 includes a wireless communication unit 8 that is the wireless terminal 5 illustrated in FIG. 4 and a power measurement meter 9 that is a power meter. For example, the power measurement meter 9 transmits the measurement result of the electric energy to the wireless communication unit 8 at regular intervals. The wireless communication unit 8, that is, the connected device communication processing unit 54 of the wireless terminal 5 passes the received measurement result to the control unit 52, and the control unit 52 stores the measurement result in a signal of a predetermined format, and the measurement result is stored. The signal is passed to the wireless communication processing unit 51. The wireless communication processing unit 51 transmits the signal received from the control unit 52 from the antenna 50 as a wireless signal. A smart meter is installed for every consumer, for example.

  The radio communication system according to the present embodiment includes radio master stations 4-1 and 4-2 and radio terminals 5-1 to 5 -M, through a management server 2 by an operator and an administrator who use the radio communication system. Centralized management and control of 5-101 to 5-L is performed.

  In the present embodiment, as described above, the frequency allocation device 1 shown in FIG. 1 determines a radio channel, that is, a radio frequency band, to be allocated to the radio master stations 4-1 and 4-2. FIG. 6 is a diagram illustrating a configuration example of the frequency allocation device 1 according to the present embodiment. As shown in FIG. 6, the frequency allocation device 1 compares the inter-cell distance and the interference determination threshold value to determine the presence / absence of an inter-cell interference relationship, and the presence / absence of the interference relationship. A group generation unit 12 that groups cells based on the cell, and a radio frequency band that is different from each other is allocated to the cell that is determined to be in an interference relationship by the interference relationship determination unit 11, and the number of radio frequency bands that are used for allocation is minimized, A communication unit 14 that performs communication processing between the channel allocation unit 13 that is a frequency allocation unit that allocates a radio frequency band for each cell and a management server 2 so that the number of cells to which a specific radio frequency band is allocated increases. And a storage unit 15. The storage unit 15 stores cell information, interference relation information, and channel arrangement information. The channel arrangement information is information indicating a result of radio channel assignment to each cell. The cell information and interference relation information will be described later. The storage unit 15 is also used to temporarily store a “radio channel arrangement candidate cell list” in a radio channel arrangement process, that is, a radio channel allocation process described later.

  Specifically, the frequency allocation device 1 is a computer system, that is, a computer. When the frequency allocation program is executed on this computer system, the computer system functions as the frequency allocation device 1. FIG. 7 is a diagram illustrating a configuration example of a computer system in which the frequency allocation device 1 according to the present embodiment is mounted. As shown in FIG. 7, the computer system includes a control unit 101, an input unit 102 that is a receiving unit, a storage unit 103, a display unit 104, a communication unit 105, and an output unit 106, which are connected via a system bus 107. Connected.

  In FIG. 7, the control unit 101 is, for example, a CPU or the like, and executes the frequency allocation program of the present embodiment. The input unit 102 includes, for example, a keyboard and a mouse, and is used by a computer system operator or the like to input various types of information. The storage unit 103 includes various memories such as a RAM (Random Access Memory) and a ROM (Read Only Memory) and a storage device such as a hard disk. The storage unit 103 is a program to be executed by the control unit 101 and necessary information obtained in the process. Memorize data, etc. The storage unit 103 is also used as a temporary storage area for programs. The display unit 104 is configured by an LCD (liquid crystal display panel) or the like, and displays various screens for the computer system user. The communication unit 105 performs communication processing. The output unit 106 is an output interface for connecting to a device such as a printer. FIG. 7 is an example, and the configuration of the computer system is not limited to the example of FIG.

  Here, an example of the operation of the computer system until the frequency allocation program of the present embodiment becomes executable will be described. In the computer system having the above-described configuration, for example, a frequency allocation program is stored in a storage unit from a CD-ROM or DVD-ROM set in a CD (Compact Disc) -ROM or DVD (Digital Versatile Disc) -ROM drive (not shown). 103 is installed. When the frequency allocation program is executed, the frequency allocation program read from the storage unit 103 is stored in a predetermined location in the storage unit 103. In this state, the control unit 101 executes the frequency allocation process according to the present embodiment in accordance with the program stored in the storage unit 103.

  In this embodiment, a program describing frequency allocation processing is provided using a CD-ROM or DVD-ROM as a recording medium. However, the present invention is not limited to this, and the configuration of the computer system and the capacity of the provided program are provided. For example, a program provided by a transmission medium such as the Internet via the communication unit 105 may be used.

  The interference relationship determination unit 11, the group generation unit 12, and the channel allocation unit 13 illustrated in FIG. 6 are included in the control unit 101 illustrated in FIG. The storage unit 15 illustrated in FIG. 6 is a part of the storage unit 103 illustrated in FIG. The communication unit 14 illustrated in FIG. 6 is included in the communication unit 105 illustrated in FIG.

  FIG. 8 is a diagram illustrating a configuration example of the management server 2 according to the present embodiment. As shown in FIG. 8, the management server 2 communicates between the management unit 21 and the frequency allocation device 1 and communication between the wireless master stations 4-1 and 4-2 via the backbone communication network 3. A communication unit 22 that performs processing and a storage unit 23 are provided. The storage unit 23 stores channel arrangement information received from the frequency allocation device 1.

  When receiving a signal from the frequency allocation device 1, the communication unit 22 passes the received signal to the management unit 21. The management unit 21 extracts channel arrangement information from the received signal and stores it in the storage unit 23. The management unit 21 reads the channel allocation information from the storage unit 23, extracts the assigned channel corresponding to each of the radio master stations 4-1 and 4-2 from the channel allocation information, and the radio master stations 4-1 and 4- A signal indicating the assigned channel corresponding to each of the wireless master stations 4-1 and 4-2 is generated every two and passed to the communication unit 22. The communication unit 22 transmits a signal to each of the wireless master stations 4-1 and 4-2 via the backbone communication network 3.

  As described above, the channel arrangement information may be input to the management server 2 by an administrator or operator of the communication system using an electronic medium, a paper medium, or the like. In this case, the management server 2 stores the input channel arrangement information in the storage unit 23.

  Specifically, the management server 2 is a computer system, that is, a computer. When the management program is executed on this computer system, the computer system functions as the management server 2. The configuration of the computer system on which the management server 2 of this embodiment is mounted is the same as the configuration illustrated in FIG. Similar to the operation described for the frequency allocation device 1, a management program is installed in the computer system, and the computer system operates as the management server 2.

  The management unit 21 illustrated in FIG. 8 is included in the control unit 101 illustrated in FIG. The storage unit 23 illustrated in FIG. 8 is a part of the storage unit 103 illustrated in FIG. The communication unit 22 illustrated in FIG. 8 is included in the communication unit 105 illustrated in FIG.

  In the above description, the frequency allocation device 1 and the management server 2 are configured as separate devices. However, the management server 2 may have a function as the frequency allocation device 1. In this case, the configuration of the management server is a configuration in which the interference relationship determination unit 11, the group generation unit 12, and the channel allocation unit 13 illustrated in FIG. 6 are added to the configuration of the management server 2 illustrated in FIG. The storage unit 23 stores cell information and interference relationship information in addition to channel arrangement information.

  Next, a radio channel assignment method according to this embodiment will be described. In the following, the channel is abbreviated as CH as appropriate. In the communication system of the present embodiment, it is assumed that a plurality of radio channels can be used, and radio channel numbers such as radio CH-1, radio CH-2, radio CH-3,. Shall be.

  Here, the definition of the cell of this Embodiment is demonstrated. FIG. 9 is a diagram illustrating an example of a cell 6-1 configured by the wireless terminals 5-1 to 5-12 that are directly or indirectly wirelessly connected to the wireless parent station 4-1 and the wireless parent station 4-1. The wireless link 201 is a wireless link with the wireless master station 4-1, and the wireless link 202 is a wireless link between wireless terminals. In FIG. 9, reference numerals 201 and 202 are assigned one by one, but a wireless link having the same shape as the wireless link 201 indicates a wireless link with the wireless master station 4-1 and has the same shape as the wireless link 202. The wireless link indicates a wireless link between wireless terminals. In this embodiment, as shown in FIG. 9, not only the direct communicable range with the wireless master station 4-1 but also each of the wireless master station 4-1 and the wireless terminals 5-1 to 5-12 under its control. The envelope of the communicable range is defined as cell 6-1. The same applies to other wireless master stations. In the present embodiment, a cell configured by each communicable range of the wireless master station 4 and the subordinate wireless terminal 5 is defined as a cell configured by the wireless master station. Define.

  The wireless master station 4-1 and the wireless terminals 5-1 to 5-12 constitute a wireless network called a so-called wireless multi-hop network or wireless mesh network. The wireless terminals 5-1 to 5-12 and the wireless master station 4-1 perform route construction processing for constructing a wireless communication route between the wireless terminals 5-1 to 5-12 and the wireless master station 4-1. . The specific contents of the route construction process, that is, the route construction procedure may be any procedure. For example, the route is constructed by the following procedure. Each of the wireless terminals 5-1 to 5-12 is on a route toward the wireless master station 4-1, and stores the address information of the terminal having the smallest number of hops from the own terminal, that is, the wireless terminal of the next hop as route information. 53. Here, a communication path between the wireless master station 4-1 and one wireless terminal 5 or between one wireless terminal 5 and another wireless terminal 5 is called a link. The wireless master station 4-1 and the wireless terminals 5-1 to 5-12 measure the link cost between the adjacent wireless master station 4-1 or the wireless terminals 5-1 to 5-12, that is, the communication line quality, etc. Obtained and held by. The cost becomes lower as the communication line quality is better.

  The wireless master station 4-1 periodically generates and transmits a control packet including address information of the terminal itself. The wireless terminal adjacent to the wireless master station 4-1 among the wireless terminals 5-1 to 5-12 stores the cost of the link with the wireless parent station 4-1 as the route cost in the received control packet, and the route A control packet storing the cost and its address information is transmitted. Thereafter, the wireless terminals 5-1 to 5-12 that have received the control packet have the link cost between the wireless terminals 5-1 to 5-12 that have transferred the control packet immediately before, in the route cost of the received control packet. The cost is added, and a control packet in which the value after the addition is stored as the route cost is transmitted. By repeating this, the radio terminals 5-1 to 5-12 can acquire the address information of the radio master station 4-1 and the route cost to the radio master station 4-1. The wireless terminals 5-1 to 5-12 may receive a plurality of control packets transmitted from the wireless master station 4-1 via a plurality of routes. In this case, the wireless terminals 5-1 to 5-12 select the control packet with the lowest route cost from the received control packets, and the wireless terminal that has transferred the selected control packet immediately before is transmitted to the wireless master station 4-1. And the address information of the wireless terminal of the determined next hop is stored as route information in association with the address information of the wireless master station 4-1.

  Thereafter, when transmitting a signal to the wireless master station 4-1, the wireless terminals 5-1 to 5-12 store the address information of the own terminal in the signal to be transmitted and hold it in the storage unit 53 of the own terminal. The signal is transmitted to the wireless terminals 5-1 to 5-12 or the wireless master station 4-1 that are the next hop based on the route information. When this signal is received by the wireless terminal, the received wireless terminal is the wireless terminal 5-1 to 5-12 or the wireless master station that is the next hop based on the path information held in its storage unit 53. The signal is transferred to 4-1. By repeating this, signals transmitted from the wireless terminals 5-1 to 5-12 arrive at the wireless master station 4-1. The wireless master station 4-1 holds the address information of the wireless terminals under its control as terminal information in the storage unit 44, and the address information of the wireless terminals 5-1 to 5-12 that are the transmission sources of the received signals. Is not included in the terminal information, the address information is added to the terminal information. When the direction from each radio terminal 5-1 to 5-12 toward the radio master station 4-1 is up, and the direction from the radio master station 4-1 to each radio terminal 5-1 to 5-12 is down, When the signals in the direction are transferred, the wireless terminals 5-1 to 5-12 hold the address information of the wireless terminals 5-1 to 5-12 that are the transfer sources immediately before the signal, so that the downlink direction is the same as the uplink direction. A signal can be transferred along a route. Alternatively, the route may be constructed in the same way as the upstream direction in the downstream direction.

  With the above procedure, a route between the wireless terminals 5-1 to 5-12 and the wireless master station 4-1 can be set. The wireless terminals 5-1 to 5-12 for which a route is set with the wireless master station 4-1 by the above procedure are referred to as wireless terminals under the wireless master station 4-1. The wireless terminals 5-1 to 5-12 may receive a plurality of control packets having different wireless master stations as transmission sources. In this case, the wireless terminal selects the control packet with the lowest route cost among the received control packets, and routes the address information of the source wireless master station included in the selected control packet and the next-hop wireless terminal. Store as information.

  Note that the above route construction procedure is an example, and the route construction method between the wireless master station 4-1 and the wireless terminals 5-1 to 5-12 is not limited to the above example. A procedure such as explicitly notifying the route to each wireless terminal from the station 4-1 may be used. Further, a plurality of routes such as a different route to the wireless master station 4-1 and a route to the wireless master station 4 other than the wireless master station 4-1 are held, and priority is given to the plurality of routes. A route to be used may be determined.

  When the route between the radio master station 4-1 and the radio terminals 5-1 to 5-12 is established, the radio master station 4-1 is connected to the radio terminals 5-1 to 5-12, that is, subordinates. Wireless communication with other wireless terminals can be performed.

  In the present embodiment, on the premise that the wireless terminals 5-1 to 5-12 communicate with each other through one wireless channel, the wireless master station 4-1 and the wireless terminals 5-1 to 5-5 constituting one cell are used. 12 communicates with the same wireless channel. In the channel assignment method according to the present embodiment, a radio channel is assigned to each cell so as to suppress interference based on the distance between the cells without using a repetitive pattern. When the repetitive pattern is used, restrictions are imposed on the arrangement of radio master stations and channel assignment. On the other hand, in the present embodiment, it is possible to increase the arrangement of the wireless master station and the degree of freedom of channel assignment as compared with the method of performing channel assignment using a repetitive pattern while suppressing interference. As a result, it is possible to reduce the number of installed wireless master stations, improve the frequency utilization efficiency, and the like.

  In the following description, a method is described in which different radio channels are always used in cells having an interference relationship. However, n (n is an integer of 1 or more) cells having an interference relationship are assigned to the same radio channel. In such a case, the n cells in the interference relationship are grouped, the group is regarded as one cell, and in the channel allocation method according to the present embodiment as described later, the group is replaced by a unit. A wireless channel may be assigned to each group.

  Next, a method for determining the presence or absence of an interference relationship between cells used in radio channel assignment according to the present embodiment will be described. For example, without using a repetitive pattern, the radio master station 4 is arranged so that the number of radio terminals 5 accommodated in the radio master station 4 is maximized, and the same radio channel is assigned to all cells. In this case, interference between cells occurs, and a desired system throughput may not be obtained. For example, in the CSMA / CA system, it is known that the system throughput decreases if the amount of traffic generated simultaneously becomes excessive. Therefore, in the present embodiment, an interference determination threshold value that is a threshold value of the inter-cell distance that can obtain a desired system throughput is set, and the actual inter-cell distance is compared with the interference determination threshold value. The presence or absence of interference relationship is determined.

[Specific example of interference judgment threshold]
As described above, in the present embodiment, a cell is configured by the communicable ranges of the wireless master station 4 and the subordinate wireless terminals 5. When the wireless terminals 5 subordinate to the wireless master station 4 transmit data to the wireless master station 4 as in the smart meter system, all communication from the wireless terminal 5 group is performed via the wireless terminal 5 relay. Collected in station 4. Further, communication from the wireless master station 4 to the subordinate radio terminals 5 group is transmitted from the radio master station 4 and distributed to the subordinate radio terminals 5 group via the relay of the radio terminals 5. For this reason, in the cell, the traffic volume increases as the area is closer to the wireless master station 4, and the traffic volume decreases as the distance from the wireless master station 4 increases.

  FIG. 10 is a diagram schematically illustrating the traffic density in the cell 60-1. Although the actual cell shape is not circular as described with reference to FIG. 9, in FIG. 10, there are a large number of wireless terminals 5 subordinate to the wireless master station 40-1 with the wireless master station 40-1 being almost equally centered. Assuming a model that exists, the cells are shown approximately circularly. The radio master station 40-1 is the same radio master station as the radio master station 4-1. The hop interval shown in FIG. 10 indicates an interval for one hop. In FIG. 10, the area from the wireless master station 40-1 to the distance where the number of hops from the master station 40-1 is 1 is the first hop. The first hop indicates a range in which the wireless master station 40-1 and the wireless terminal 5 can communicate directly.

  The second and subsequent hops are determined based on the distance that can be communicated between the wireless terminals 5. That is, in FIG. 10, the hop count indicates a virtual hop count calculated based on the distance at which direct communication is possible between the wireless terminals 5. FIG. 10 shows the traffic density for each number of hops. As shown in FIG. 10, since all the traffic is concentrated on the radio master station 40-1 at the center of the cell 60-1, the closer to the radio master station 40-1, the higher the traffic density.

  FIG. 11 is a diagram schematically illustrating the traffic density of two cells. The cell 60-1 is the same as the cell 60-1 shown in FIG. The radio master station 40-2 is the same radio master station as the radio master station 4-1. Here, it is assumed that the cell 60-2 adjacent to the cell 60-1 has the same traffic density as the cell 60-1. As shown in FIG. 11, the cell 60-1 and the cell 60-2 overlap, but the overlapping portion is a region having a relatively low traffic density. In this way, when adjacent traffic density regions overlap each other between adjacent cells, the influence of interference between adjacent cells is relatively small.

  Therefore, for example, if a desired throughput can be obtained if n (n is an integer of 1 or more) hops can be secured for a portion that does not overlap with an adjacent cell, n or more portions that do not overlap with an adjacent cell are secured. Whether or not it is possible can be used to determine the presence or absence of interference. Specifically, when n hops or more are secured in a portion that does not overlap with an adjacent cell, it is determined that there is no interference when the inter-cell distance is “n hop distance × 2” or more, and the inter-cell distance is “ If it is less than “n hop distance × 2”, it is determined that there is an interference relationship. The n-hop distance is a distance from the wireless master station at a point where the number of hops from the wireless master station is n hops, and indicates a distance calculated based on a distance that can be directly communicated as described above. . The inter-cell distance is the distance between the wireless master station 40-1 and the wireless master station 40-2 in the example of FIG. As described above, the distance between the wireless master stations can be used as the inter-cell distance. For example, the distance between the centers of the cells may be used. The above-described n-hop distance × 2 is an interference determination threshold value for determining whether or not two cells are in an interference relationship.

  The example of FIG. 11 shows an example in which the inter-cell distance matches the interference determination threshold value. Therefore, when the distance between the wireless master station 40-1 and the wireless master station 40-2 is shorter than the state shown in FIG. 11, it is determined that the cells 60-1 and 60-2 are in an interference relationship. When the distance between the wireless master station 40-1 and the wireless master station 40-2 is longer than that shown in FIG. 11, it is determined that the cell 60-1 and the cell 60-2 are not in an interference relationship.

  Note that the value of the directly communicable distance used for calculating the n-hop distance may vary depending on the region. For example, buildings are densely located in urban areas, and the range in which direct communication between the wireless master station 4 and the wireless terminal 5 or the wireless terminal 5 is reduced, but direct communication is performed in areas where the density of buildings is low. The possible range is widened. Therefore, even with the same n-hop distance, it varies depending on the region. For this reason, you may change the value of n hop distance by area.

  In the above description, the example in which the interference determination threshold value is obtained by calculation using the virtual hop number has been shown. However, the calculation method for obtaining the interference determination threshold value by calculation uses the virtual hop number. It is not limited to the above example. Further, the interference determination threshold value may be determined based on an actual measurement value. For example, a cell may be actually constructed by a multi-hop network, a distance at which a desired throughput is obtained may be measured, and the above-described interference determination threshold may be determined based on the measurement result.

  The interference determination threshold value may be determined according to the traffic amount. As the traffic volume, for example, the reciprocal of the number of wireless terminals 5 under the control of the wireless master station 4, that is, the inverse of the number of wireless terminals 5 accommodated by the wireless master station 4 can be used. For example, the above “n hop distance × 2” may be multiplied by a weight W corresponding to the traffic amount. The weight W is a value having a positive correlation with the reciprocal of the number of wireless terminals 5 accommodated by the wireless master station 4. For example, this weight is set to a value that is directly proportional to the reciprocal of the number of wireless terminals 5 accommodated in the wireless master station 4. Further, the interference determination threshold value may be calculated by “an arbitrary distance as a reference × weight W” without using “n hop distance × 2”.

[Determination of interference relationship between cells]
FIG. 12 is a diagram illustrating an example of a determination result of presence / absence of an interference relationship between cells. FIG. 12 illustrates the result of determining the presence or absence of an inter-cell interference relationship for 14 cells 6-1 to 6-14. In FIG. 12, each cell is indicated by a circle for simplification of the drawing. However, as described above, the cell according to the present embodiment is a cell configured by the wireless master station 4 and the subordinate wireless terminal 5. . The location where the straight line connecting the cells in FIG. 12 is described indicates that the cells are in an interference relationship. For example, the cell 6-5 has an interference relationship with the cells 6-6, 6-7, and 6-8. On the other hand, the cell 6-1 has no interference relationship with any cell.

  FIG. 13 is a flowchart showing an example of a procedure for determining whether or not there is an interference relationship in the frequency allocation device 1 according to the present embodiment. As shown in FIG. 13, the interference relationship determination unit 11 of the frequency allocation device 1 first initializes interference relationship information, which is information indicating the presence or absence of an interference relationship for each cell (step S1). In this initialization, a value indicating that there is no inter-cell interference for all cell combinations is stored as interference relation information.

  The interference relation information is held as a table having the format shown in FIG. 14, for example. FIG. 14 is a diagram illustrating a configuration example of interference relation information. In the example of FIG. 14, the cell numbers are shown in the vertical direction and the horizontal direction, and the column where the cell numbers in the vertical direction and the horizontal direction intersect indicates the presence or absence of interference between the cells of the corresponding cell numbers. FIG. 14 shows that a combination of cells with a mark “◯” is in an interference relationship, and that a combination of cells that are blank is not in an interference relationship. FIG. 14 stores information corresponding to the presence or absence of the interference relationship shown in FIG. In FIG. 14, the presence / absence of interference is indicated by the presence / absence of ◯. Actually, the interference relationship information stores, for example, 1 when there is an interference relationship and 0 when there is no interference relationship. For example, the presence or absence of an interference relationship may be indicated by a numerical value. The rightmost column in FIG. 14 shows the number of cells having an interference relationship with the cell for the cell corresponding to each cell number described in the vertical direction. In the leftmost column of FIG. 14, group numbers of interference related cell groups that are grouped based on interference relationship information described later are described. The number of cells in the interference relationship in the rightmost column of FIG. 14 and the group number of the interference cell group in the leftmost column of FIG. 14 are used in grouping described later or are the result of grouping, and are included in the interference relationship information. These may not be provided, and these may be managed by another table.

  Returning to the description of FIG. 13, the interference relationship determination unit 11 sets i as a counter to 1 (step S <b> 2), and sets j as a counter to 1 (step S <b> 3). Next, the interference relationship determination unit 11 determines whether i = j (step S4). If i = j is not satisfied (No in step S4), it is determined whether the cell 6-i and the cell 6-j are in an interference relationship (step S5). Specifically, the interference relationship determination unit 11 acquires the installation positions of the wireless master stations 4 corresponding to the cells 6-i and 6-j from the cell information stored in the storage unit 15, and acquires the acquired wireless parent. Based on the installation position of the station 4, the inter-cell distance between the cell 6-i and the cell 6-j is calculated. Then, the interference relationship determination unit 11 determines whether or not the inter-cell distance is equal to or greater than the above-described interference determination threshold value, and determines that there is no interference when the inter-cell distance is equal to or greater than the interference determination threshold value. If the inter-cell distance is less than the interference determination threshold, it is determined that there is interference. It is assumed that the cell information stores the position of the wireless master station 4 constituting each cell.

When it is determined that the cell 6-i and the cell 6-j are in an interference relationship (Yes in step S6), the interference relationship determination unit 11 determines the interference relationship between the cell 6-i and the cell 6-j in the interference relationship information. The information indicating the presence or absence of is updated to a value indicating that there is an interference relationship (step S7). Then, the interference relationship determination unit 11 determines whether j is equal to N _max that is the number of cells. If j is not equal to N _max (step S8 No), j = j + 1 is set (step S9). Return to step S4.

If it is determined in step S8 that j is equal to N _max (step S8 Yes), it is determined whether i is equal to N _max (step S10). If i is not equal to N _max (No in step S10), i = i + 1 is set (step S11), and the process returns to step S3. If it is determined in step S10 that i is equal to N _max (step S10 Yes), the process ends. If it is determined in step S4 that i is equal to j (Yes in step S4) and if it is determined in step S6 that there is no interference relationship (No in step S6), the process proceeds to step S8.

[Creation of interference cell group]
In order to avoid mutual interference, it is necessary to arrange different radio channels in the cells that are determined to have the interference relationship by the above-described determination of the presence or absence of the interference relationship. In the present embodiment, an interference-related cell group that is a group of cells having an interference relationship is generated as an arrangement unit for arranging radio channels.

  Here, the interference-related cell group includes cell groups that have an interference relationship with one or more cells in the group. However, a cell having no interference relationship with all cells forms an interference relationship cell group only with the cell concerned.

  The group generation unit 12 counts the number of cells having an interference relationship with the cell for each cell based on the interference relationship information. The counting result is the numerical value shown in the rightmost column of FIG. Next, the group generation unit 12 searches for a cell having no interference relationship with all the cells based on the above counting result, and if there is a corresponding cell, generates an interference cell group composed of this cell. To do. Next, the group generation unit 12 selects one of the cells in which one or more cells having the interference relationship exist based on the interference relationship information, and the interference relationship between the selected cell and the cell having the interference relationship is selected. Create a cell group. And the group production | generation part 12 extracts the cell which has an interference relationship with this cell for every cell which comprises this interference related cell group based on interference relationship information, and adds the extracted cell to this interference related cell group. . By repeating the above operation, an interference related cell group is generated.

  The leftmost column in FIG. 14 shows a group generated by the group generation unit 12, that is, a grouping result. Interference-related cell group # 1 includes only cells 6-1 that have no interference relationship with other cells. Interference-related cell group # 2 includes cells 6-2 to 6-4 that are cell groups that have an interference relationship with one or more cells in the group. Interference-related cell group # 3 includes cells 6-5 to 6-14 that are cell groups that have an interference relationship with one or more cells in the group.

[Radio channel arrangement for each interference cell group]
Next, a method for arranging a radio channel for each cell in the interference related cell group in units of the interference related cell group described above will be described. FIG. 15 is a flowchart illustrating an example of a radio channel arrangement procedure within an interference related cell group. The channel assignment unit 13 performs the process shown in FIG. 15 for each interference related cell group.

  As illustrated in FIG. 15, the channel allocation unit 13 selects a cell having the maximum number of cells having an interference relationship among the interference-related cell groups that are targets of channel arrangement (step S <b> 21). When there are a plurality of cells having the maximum number of cells having an interference relationship, the channel assignment unit 13 selects an arbitrary cell among the cells having the maximum number of cells having an interference relationship. For example, the cell with the youngest cell number is selected.

  The channel assignment unit 13 arranges, that is, assigns the youngest radio channel to the selected cell (step S22). Next, all the cells in which the radio channel having an interference relationship with the selected cell is not arranged are registered in the “radio channel arrangement candidate cell list” (step S23). Specifically, the channel allocating unit 13 stores, as a “radio channel arrangement candidate cell list”, all cells in which radio channels that have an interference relationship with the selected cell are not arranged.

  Next, the channel allocation unit 13 determines whether or not radio channels are allocated to all the cells constituting the interference related cell group (step S24). When there is a cell in which the radio channel is not arranged among the cells constituting the interference related cell group (No in step S24), the channel allocation unit 13 sets the interference relationship among the cells in the “radio channel arrangement candidate cell list”. A cell having the largest number of cells is selected (step S25). When there are a plurality of cells having the maximum number of cells having an interference relationship, the channel assignment unit 13 selects an arbitrary cell among the cells having the maximum number of cells having an interference relationship. For example, the cell with the youngest cell number is selected.

  Next, for the cell selected in step S25, the youngest radio channel is arranged except for the radio channel set in the cell having an interference relationship with the selected cell, and the cell selected in step S25 is changed to “ It deletes from a radio | wireless channel arrangement | positioning candidate cell list "(step S26), and returns to step S23. In the second and subsequent steps S23, the cell selected in step S25 is used as the selected cell.

  If it is determined in step S24 that radio channels are allocated to all the cells constituting the interference cell group (Yes in step S24), the channel allocation unit 13 calculates the allocation number for each radio channel number, The radio channel numbers arranged in order from the youngest radio channel are replaced in descending order (step S27), and the process ends. That is, in step S27, the radio frequency band to be allocated is changed so that a radio channel having a lower radio channel number as an identification number is allocated as the number of arrangements, which is the number of cells to which the radio channel is allocated, increases for each radio channel. In step S27, when there are a plurality of radio channels with the same number of arrangements, the channel assignment unit 13 preferentially replaces the youngest radio channel among the radio channels with the same number of arrangements.

  When the radio channel assignment process is performed on the interference related cell group # 1 shown in FIG. 14 according to the flowchart shown in FIG. 15, the following operation is performed. In step S21, the cell 6-1 is selected, and in step S22, the youngest radio CH-1 is arranged in the cell 6-1. In step S23, since there is no cell having an interference relationship with the cell 6-1, nothing is stored in the “wireless channel arrangement candidate cell list”. In step S24, it is determined that radio channels are arranged in all the cells constituting the interference related cell group # 1, and the process proceeds to step S27. In step S27, since the youngest radio CH-1 is arranged in the cell 6-1, there is no radio channel change due to radio channel replacement, and the process is terminated. In this way, the radio channel arranged in each cell becomes the assigned channel assigned to each cell.

  Further, when the radio channel assignment processing is performed on the interference related cell group # 2 shown in FIG. 14 according to the flowchart shown in FIG. 15, the following operation is performed. In step S21, the cell 6-3 having the largest number of cells having an interference relationship is selected, and in step S22, the youngest radio CH-1 is arranged in the cell 6-3. In step S23, cells 6-2 and 6-4 that have an interference relationship with the cell 6-3 and have not been set with a radio channel are registered in the “radio channel arrangement candidate cell list”. In the determination in step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, among the cells registered in the “wireless channel arrangement candidate cell list”, there are two cells 6-2 and 6-4 with the largest number of cells having the interference relationship, and of these, the cell Cell 6-2 with a lower number is selected. In step S26, since the wireless CH-1 is already arranged in the cell 6-3 that has an interference relationship with the cell 6-2, the youngest wireless channel excluding the wireless CH-1 is included in the cell 6-2. Wireless CH-2 is placed, and cell 6-2 is deleted from the “wireless channel placement candidate cell list”.

  Then, the process returns to step S23. In step S23, since the radio channel is already allocated to the cell 6-3 that has an interference relationship with the cell 6-2 selected in step S25, the radio channel allocation candidate cell list is displayed. Will not be registered. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell 6-4 registered in the “wireless channel arrangement candidate cell list” is selected. In Step S26, since the wireless CH-1 is allocated to the cell 6-3 that has an interference relationship with the cell 6-4, the wireless CH-2 is allocated to the cell 6-4, and “radio channel allocation” is performed. The cell 6-4 is deleted from the “candidate cell list”.

  Then, the process returns to step S23. In step S23, since the radio channel is already allocated to the cell 6-3 that is in an interference relationship with the cell 6-4 selected in step S25, the radio channel allocation candidate cell list is displayed. Will not be registered. In step S24, it is determined that radio channels are arranged in all the cells constituting the interference related cell group # 2, and the process proceeds to step S27. In step S27, since the number of wireless CH-1 is 1, and the number of wireless CH-2 is 2, wireless CH-2 with a large number of arrangements is replaced with wireless CH-1, and a wireless CH with a small number of arrangements is replaced. -1 is replaced with wireless CH-2, and the process is terminated. Thereby, the radio CH-2 is arranged in the cell 6-3, and the radio CH-1 is arranged in the cells 6-2 and 6-4.

  Further, when the radio channel assignment process is performed on the interference-related cell group # 3 shown in FIG. 14 according to the flowchart shown in FIG. 15, the following operation is performed. In step S21, the cell 6-8 having the smallest cell number is selected from the cells 6-8 and 6-11 having the largest number of cells having an interference relationship. In step S22, the cell 6-8 is assigned to the radio CH-. 1 is arranged. In step S23, cells 6-5, 6-6, 6-7, 6-9, 6-11 having an interference relationship with the cell 6-8 are registered in the “wireless channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell 6-11 having the largest number of cells in the interference relationship among the cells registered in the “wireless channel arrangement candidate cell list” is selected. In Step S26, since the wireless CH-1 is allocated to the cell 6-8 that has an interference relationship with the cell 6-11, the wireless CH-2 is allocated to the cell 6-11, and the "radio channel allocation" The cell 6-11 is deleted from the “candidate cell list”.

  Then, returning to step S23, in step S23, the cells 6-7, 6-10, 6-12, and 6-13 in which the radio channel in the interference relationship with the cell 6-11 selected in step S25 is not set are “ It is registered in the “wireless channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, among the cells registered in the “wireless channel arrangement candidate cell list”, the cell 6-7 having the largest number of cells having an interference relationship and the cell 6-7 having the smallest cell number among the cells 6-12. Is selected. In step S26, the wireless CH-1 is allocated to the cell 6-8 that has an interference relationship with the cell 6-7, and the wireless CH-2 is allocated to the cell 6-11 that has an interference relationship with the cell 6-7. Therefore, the wireless CH-3 is placed in the cell 6-7, and the cell 6-7 is deleted from the “wireless channel placement candidate cell list”.

  Then, returning to step S23, in step S23, the cells 6-5 and 6-10 in which the radio channel having the interference relationship with the cell 6-7 selected in step S25 is not set are added to the “radio channel arrangement candidate cell list”. be registered. Therefore, at this time, cells 6-5, 6-6, 6-9, 6-10, 6-12, and 6-13 are registered in the “wireless channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell 6-12 having the largest number of cells having an interference relationship among the cells registered in the “wireless channel arrangement candidate cell list” is selected. In step S26, since the wireless CH-2 is allocated to the cell 6-11 that has an interference relationship with the cell 6-12, the wireless CH-1 is allocated to the cell 6-12, and the "radio channel allocation" The cell 6-12 is deleted from the “candidate cell list”.

  Then, returning to step S23, in step S23, the cells 6-9, 6-13, and 6-14 in which the radio channel in the interference relationship with the cell 6-12 selected in step S25 is not set are “radio channel arrangement candidates”. It is registered in the “cell list”. Therefore, at this time, cells 6-5, 6-6, 6-9, 6-10, 6-12, 6-13, and 6-14 are registered in the “wireless channel arrangement candidate cell list”. . In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, among the cells 6-5, 6-6, 6-9, and 6-13 having the largest number of cells in the interference relationship among the cells registered in the “wireless channel arrangement candidate cell list”. The cell 6-5 with the smallest cell number is selected. In step S26, the wireless CH-3 is allocated to the cell 6-7 that has an interference relationship with the cell 6-5, and the wireless CH-1 is allocated to the cell 6-8 that has an interference relationship with the cell 6-5. Therefore, the wireless CH-2 is placed in the cell 6-5, and the cell 6-5 is deleted from the “wireless channel placement candidate cell list”.

  Then, returning to step S23, in step S23, the cell 6-6 in which the radio channel having the interference relationship with the cell 6-5 selected in step S25 is not set is registered in the “radio channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell number is the highest among the cells 6-6, 6-9, and 6-13 having the largest number of cells having an interference relationship among the cells registered in the “wireless channel arrangement candidate cell list”. Young cell 6-6 is selected. In step S26, the wireless CH-2 is allocated to the cell 6-5 that has an interference relationship with the cell 6-6, and the wireless CH-1 is allocated to the cell 6-8 that has an interference relationship with the cell 6-6. Therefore, the wireless CH-3 is placed in the cell 6-6, and the cell 6-6 is deleted from the “wireless channel placement candidate cell list”.

  Then, returning to step S23, in step S23, the cell 6-9 in which the radio channel having the interference relationship with the cell 6-6 selected in step S25 is not set is registered in the “radio channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell 6-9, 6-13 with the smallest cell number among the cells 6-9 and 6-13 having the largest number of cells in the interference relationship among the cells registered in the “wireless channel arrangement candidate cell list”. 9 is selected. In step S26, the wireless CH-3 is allocated to the cell 6-6 that has an interference relationship with the cell 6-9, and the wireless CH-1 is allocated to the cell 6-8 that has an interference relationship with the cell 6-9. Then, since the radio CH-1 is arranged for the cell 6-12 that has an interference relationship with the cell 6-9, the radio CH-2 is arranged for the cell 6-9. Cells 6-9 are deleted from the “list”.

  Then, returning to step S23, in step S23, since there is no cell in which the radio channel having an interference relationship with the cell 6-9 selected in step S25 is not set, the cell is not registered in the “radio channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell 6-13 having the largest number of cells in the interference relationship among the cells registered in the “wireless channel arrangement candidate cell list” is selected. In step S26, the wireless CH-2 is allocated to the cell 6-11 that has an interference relationship with the cell 6-13, and the wireless CH-1 is allocated to the cell 6-12 that has an interference relationship with the cell 6-13. Therefore, the wireless CH-3 is placed in the cell 6-13, and the cell 6-13 is deleted from the “wireless channel placement candidate cell list”.

  Then, returning to step S23, in step S23, the cell 6-14 in which the radio channel having the interference relationship with the cell 6-13 selected in step S25 is not set is registered in the “radio channel arrangement candidate cell list”. In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, among the cells 6-10 and 6-14 having the largest number of cells having an interference relationship among the cells registered in the “wireless channel arrangement candidate cell list”, the cell 6-10 having the smallest cell number is selected. Selected. In step S26, the wireless CH-3 is allocated to the cell 6-7 that has an interference relationship with the cell 6-10, and the wireless CH-2 is allocated to the cell 6-11 that has an interference relationship with the cell 6-10. Therefore, the wireless CH-1 is placed in the cell 6-10, and the cell 6-10 is deleted from the “wireless channel placement candidate cell list”.

  Then, returning to step S23, in step S23, since there is no cell in which the radio channel having the interference relationship with the cell 6-10 selected in step S25 is not set, the cell is not registered in the “radio channel arrangement candidate cell list”. . In step S24, it is determined that there is a cell in which no radio channel is arranged, and the process proceeds to step S25. In step S25, the cell 6-14 registered in the “wireless channel arrangement candidate cell list” is selected. In step S26, the wireless CH-1 is allocated to the cell 6-12 that has an interference relationship with the cell 6-14, and the wireless CH-3 is allocated to the cell 6-13 that has an interference relationship with the cell 6-14. Therefore, the wireless CH-2 is placed in the cell 6-14, and the cell 6-14 is deleted from the “wireless channel placement candidate cell list”.

  Then, returning to step S23, in step S23, since there is no cell in which the radio channel having the interference relationship with the cell 6-14 selected in step S25 is not set, the cell is not registered in the “radio channel arrangement candidate cell list”. . In step S24, it is determined that radio channels are arranged in all the cells constituting the interference related cell group # 3, and the process proceeds to step S27. In step S27, the number of wireless CH-1 is 3, the number of wireless CH-2 is 4, and the number of wireless CH-3 is 3, so that the wireless CH-2 with the largest number is arranged. Is replaced with wireless CH-1. Also, since the number of radio CH-1 and radio CH-4 is the same, the youngest radio CH-1 of radio CH-1 and radio CH-4 is replaced with radio CH-2, and the last radio CH-3 is left as it is. As a result, the wireless CH-1 is arranged in the cells 6-5, 6-9, 6-11, 6-14, and the wireless CH-2 is arranged in the cells 6-8, 6-10, 6-12. In the cells 6-6, 6-7, 6-13, the wireless CH-3 is arranged.

  Further, the flowchart shown in FIG. 15 is an example, and a procedure in which different radio channels are arranged between cells in an interference relationship, the number of radio channels to be used is minimized, and a large number of specific radio channels are arranged. Well, the specific procedure is not limited to the example of FIG. Moreover, even if it is the procedure which arrange | positions so that a different radio channel may be arrange | positioned between the cells which have an interference relationship, and the number of radio channels used may be minimized, omitting the procedure by which a lot of specific radio channels are arranged. The possibility that the frequency can be reused while avoiding interference can be improved.

  FIG. 16 is a diagram illustrating an example of a radio channel arrangement result. FIG. 16 shows the result of performing the above-described radio channel assignment processing based on the interference relationship information shown in FIG. As a result, the channel allocation unit 13 arranges the wireless CH-1 in the cells 6-5, 6-9, 6-11, 6-14, and wirelessly in the cells 6-8, 6-10, 6-12. CH-2 is arranged, and in cells 6-6, 6-7, and 6-13, a result indicating that the wireless CH-3 is arranged is transmitted to the management server 2 via the communication unit 14 as channel arrangement information. To do.

  As described above, in the radio channel arrangement method according to the present embodiment, a radio channel different from the first cell is arranged with respect to the second cell having an interference relationship with the first cell in which the radio channel is already arranged. By doing so, it is avoided to place the same radio channel between cells in an interference relationship. On the other hand, for cells that are not in an interference relationship, it is possible to arrange the same radio channel regardless of whether or not these cells are adjacent cells. In addition, it is possible to realize channel arrangement that avoids interference with the minimum number of radio channels by placing priority on the lowest number while avoiding arranging the same radio channel between cells having interference relations. it can.

  Furthermore, in the radio channel arrangement result, by replacing the radio channel number arranged in order from the youngest radio channel in the descending order of the arrangement number for each radio channel number, the frequency of using the younger radio channel is increased, The frequency of using the old radio channel is decreasing. Thereby, the possibility of reuse of the old radio channel can be improved.

  As described above, according to the radio channel arrangement method of the present embodiment, it is possible to perform radio channel arrangement with the minimum number of radio channels based on any cell arrangement regardless of the conventional repetitive pattern. The finite frequency resource can be effectively used.

  In this embodiment, the young radio channel is preferentially arranged. However, when there is a priority of a radio channel other than the radio channel, a high priority radio channel is used by using the priority. May be arranged with priority.

  In the above description, radio channels are arranged in cells in units of interference related cell groups. However, radio channels may be arranged in cells based on the presence / absence of interference relationships without grouping. In this case, since all cells correspond to the same interference-related cell group, the flowchart shown in FIG. 15 may be implemented for all cells.

  Further, in the present embodiment, unlike the case of using a repetitive pattern, since the cell arrangement can be arbitrarily set, the number of radio master stations can be reduced, thereby reducing resource, energy, and cost. Can be realized.

Embodiment 2. FIG.
In the second embodiment, a timing at which the radio channel assignment process described in the first embodiment is performed and a timing at which the result of the radio channel assignment process is reflected on each of the radio master stations 4-1 and 4-2 will be described. The configuration of the communication system of the present embodiment and the configuration of each device configuring the communication system are the same as those of the first embodiment. Hereinafter, differences from the first embodiment will be described. The radio channel assignment process of the present embodiment is the same as that of the first embodiment.

  As a first method, there is a method of prescribing the processing timing of the radio channel assignment process and reflecting the result to the respective radio master stations 4-1 and 4-2 as soon as the result of the radio channel assignment process is calculated. is there. In this case, in the first wireless channel assignment process, as soon as the result of wireless channel assignment is calculated, the result is reflected on each of the wireless master stations 4-1 and 4-2. After that, the frequency allocation apparatus 1 performs the radio channel allocation process described in the first embodiment on the interference-related cell group that needs to change the radio channel when the radio channel needs to be changed. Then, the result is reflected to each radio master station for the interference-related cell group whose radio channel is changed. In the above example, the recalculation of the radio channel arrangement is performed for the interference related cell group whose radio channel is changed, but may be re-started from the generation of the interference related cell group.

In the following, an example of criteria for determining whether or not a radio channel needs to be changed is described.
(1) Addition, deletion, or relocation of a radio master station has occurred (2) Either one of the above (1) and (2) in which the increase or decrease in traffic exceeds a threshold value may be used as a criterion However, when at least one of the criteria (1) and (2) is satisfied, it may be determined that the radio channel needs to be changed.

  As the traffic volume used in the criterion of (2), for example, the measured traffic volume may be used, the number of radio master stations 4 in the interference related cell group, or the radio master stations 4 in the interference related cell group. The total number of wireless terminals 5 connected to the can be used. Then, when the increase amount of the traffic amount of the interference related cell group exceeds the first threshold value, or when the decrease amount of the traffic amount of the interference related cell group exceeds the second threshold value, the interference It is determined that the increase or decrease in the traffic volume of the related cell group has exceeded the threshold value.

  Upon receiving the channel allocation information from the frequency allocation device 1, the management server 2 extracts the allocation channel corresponding to each radio master station 4 based on the channel allocation information, and notifies the radio master station 4 of the allocated channel. In the channel arrangement information, information corresponding to a cell to be recalculated is stored in the second and subsequent radio channel assignment processes, that is, recalculation. The radio channel is not changed except for the recalculated cell. Based on the channel allocation information received from the frequency allocation device 1 as a result of recalculation, the management server 2 reassigns the channel allocated by recalculation to the radio master station 4 that needs to change the radio channel, that is, the allocation after recalculation. Notify the radio channel. Further, the management server 2 partially updates the channel allocation information stored in the storage unit 23 based on the channel allocation information received from the frequency allocation device 1 as a result of recalculation.

  Further, for example, when the frequency allocation device 1 generates channel arrangement information based on the future arrangement of the radio master station 4 to some extent, the channel arrangement information is not immediately reflected in the setting in the radio master station 4. If it is determined whether or not it is necessary to change the wireless channel, and it is determined that the wireless channel needs to be changed, it is conceivable to set the wireless master station 4. In the initial state, as described above, the operation channel of the wireless master station 4 uses the same predetermined wireless channel. For example, wireless CH-1 is used.

  FIG. 17 is a flowchart illustrating an example of a radio channel arrangement and setting process procedure according to the present embodiment. For example, the frequency allocation device 1 and the management server 2 periodically perform the process shown in FIG. Moreover, when there is a change in the configuration of the wireless communication system, the processing illustrated in FIG. 17 may be performed.

  As shown in FIG. 17, first, the frequency allocation device 1 arranges radio channels by the radio channel arrangement method described in the first embodiment (step S31). Thereby, channel arrangement information is generated. As described in the first embodiment, the channel allocation information is transmitted from the frequency allocation device 1 to the management server 2 or is transferred from the frequency allocation device 1 to the management server 2 offline. Note that this process may be omitted if there is no addition, deletion, or change of the radio master station since the previous generation of channel arrangement information, and it is not necessary to recalculate the radio channel. In the second and subsequent radio channel assignment processes, recalculation is performed for interference-related cell groups that require recalculation. When the management server 2 receives the recalculated channel allocation information from the frequency allocation device 1, it receives the channel allocation information stored in the storage unit 23 from the frequency allocation device 1 as a result of the recalculation. Suppose that it is partially updated based on channel arrangement information. In the second and subsequent radio channel assignment processes, the process may be repeated from the generation of the interference related cell group.

  The management unit 21 of the management server 2 determines whether it is necessary to change the radio channel (step S32). The determination of whether or not it is necessary to change the radio channel includes two determination processes: a first determination process and a second determination process described below.

  In the first determination process, for each interference related cell group, it is determined whether or not the traffic volume exceeds the upper threshold, and if there is an interference related cell group that exceeds the upper threshold, the interference It is determined that it is necessary to change the radio channel to the assigned channel for all cells in the related cell group. Next, it is determined whether or not the traffic volume is lower than the lower threshold, and if there is an interference related cell group that is lower than the lower threshold and has already been changed to the assigned channel, the interference relationship It is determined that the radio channel needs to be changed to the initial channel for all the cells in the cell group. Further, if there is an interference related cell group whose traffic reduction has exceeded the threshold and has already been changed to an assigned channel, the radio channel is transmitted to all cells in the interference cell group. Is determined to be a change to the initial channel. Here, the traffic amount may be the traffic amount itself, as in the case of the determination criterion (2) described above, or the number of wireless master stations in the interference-related cell group, the total number of wireless terminals, or the like. Further, in the above, it is determined whether or not the traffic volume exceeds the upper threshold and whether or not the lower threshold is exceeded with the interference related cell group as a unit. For example, the determination unit may be changed.

  In the second determination process, in the cell group determined to require the radio channel change to the assigned channel in the first determination process, the latest channel arrangement information held by itself is not reflected, that is, the radio master station 4 is determined. Specifically, the management server 2 determines that the operation channel set in the wireless master station 4 matches the channel assigned to the cell corresponding to the wireless master station 4 included in the channel arrangement information. If it is determined that the latest channel arrangement information has been reflected in the wireless master station 4 and the operation channel does not match the assigned channel, the latest channel arrangement information is reflected in the wireless master station 4. Judge that it is not. Further, it is determined whether or not there is a cell in which the initial channel is not set, that is, the radio master station 4 in the cell group determined to require the radio channel change to the initial channel in the first determination process. Specifically, when the operation channel set in the wireless master station 4 is the initial channel, the management server 2 determines that the change to the initial channel has been reflected in the wireless master station 4, and the above-described operation channel And the initial channel do not match, it is determined that the wireless master station 4 does not reflect the change to the initial channel.

  The management server 2 includes a cell corresponding to the radio master station 4 determined to require a radio channel change in the second determination process among the cells belonging to the interference cell group determined to require the radio channel change in the first determination process. And the process proceeds to step S33.

  If there is no wireless master station 4 that is determined to require a wireless channel change in the second determination process, the process ends.

  In step S33, the management server 2 performs a wireless channel setting process (step S33) and ends the process. Specifically, the management unit 21 of the management server 2 notifies the radio master station 4 that configures the cell determined to require radio channel change to the radio master station 4 that indicates the channel assigned to the radio master station 4 and the radio channel change timing. Is output to the communication unit 22. The communication unit 22 transmits the signal to each wireless master station 4 via the backbone communication network 3. The radio channel change timing may be a timing uniquely determined by the present system, and may be an absolute time or a relative time. The radio master station 4 holds the notified allocation channel and radio channel change timing in the storage unit 44 and notifies the radio terminal 5 subordinate to the radio master station 4 of the allocation channel and radio channel change timing. Receiving this notification, the wireless terminal 5 holds the notified allocation channel and wireless channel change timing in the storage unit 53.

  Thereafter, at the radio channel change timing described above, the control units of the radio master station 4 and the radio terminal 5 instruct the radio communication processing units to operate on the assigned channels held in the respective storage units, and The communication processing unit starts operation on the assigned channel. Thereby, starting from the radio channel change timing, the radio master station 4 and the subordinate radio terminal 5 operate in the assigned channel, and the radio channel arranged in the radio channel assignment process is arranged in the cell.

  The process shown in FIG. 17 is effective, for example, in a system where the number of wireless terminals is small and inter-cell interference does not become a problem at the beginning of operation. In a smart meter system or the like, radio channel assignment processing is performed on the premise of a completed system, but the radio master station 4 and the radio terminal 5 are arranged over a long time from the start of operation, and the system is completed. Therefore, immediately after the start of operation, there are few radio master stations 4 and radio terminals 5 that are actually installed, and in fact, inter-cell interference is not a problem in many cases. In such a case, in the initial state, communication is performed using the same frequency in all cells. In step S32 in FIG. 17, when the traffic volume exceeds the upper threshold value, the result of the radio channel allocation process is reflected. Thereby, since the single radio channel is used in the initial stage of operation, the radio frequency band can be reused.

  Further, in the above example, both the wireless master station 4 and the wireless terminal 5 are switched to the assigned channel at the same time. However, the wireless channel that the wireless master station 4 operates by notifying the assigned channel only to the wireless master station 4. May be switched to the assigned channel, and the wireless terminal 5 may dynamically select the wireless master station 4 of the optimal wireless channel autonomously. In this case, for example, among the control packets received by each wireless channel while the wireless terminal 5 sequentially changes the wireless channel, the wireless channel that has received the control packet with the lowest route cost is set as the operation channel, and the control packet The source wireless master station 4 is selected as the wireless master station 4 to which the terminal is connected.

  As described above, in the present embodiment, the radio channel assignment process and the process of reflecting the result of the radio channel assignment process are performed in consideration of various conditions. Thereby, a radio channel can be set at an appropriate timing according to the system to be used.

Embodiment 3 FIG.
FIG. 18 is a diagram of a configuration example of a communication system according to the third embodiment of the present invention. The communication system according to the present embodiment can be wirelessly connected to base stations 402-1 and 402-2, a control station 401 that controls base stations 402-1 and 402-2, and base stations 402-1 and 402-2. Wireless terminals 403-1 to 403-5.

  In the present embodiment, the control station 401 has the functions of the frequency allocation device 1 and the management server 2 of the first embodiment. The frequency allocation device 1 according to the first embodiment may be provided separately from the control station 401, and the control station 401 may have the function of the management server 2.

  FIG. 19 is a diagram showing the definition of a cell in the present embodiment. In the present embodiment, a range in which base station 402-1 and a wireless terminal can communicate directly is defined as cell 301. Similarly, for other base stations, a range in which each base station and a wireless terminal can communicate directly is defined as a cell.

  As in the frequency allocation apparatus 1 of the first embodiment, the control station 401 of this embodiment determines whether or not there is an interference relationship for each cell and generates an interference related cell group as defined in FIG. Thus, a radio channel is arranged for each interference related cell group. In this embodiment, an interference determination threshold based on the number of hops cannot be used as an interference determination threshold used in the presence or absence of an interference relationship. However, if an interference determination threshold that provides a desired system throughput is set, Good. The radio channel assignment process of the present embodiment is the same as the radio channel assignment process of the first embodiment, except that the cell definition is different and the interference judgment threshold based on the number of hops is not used as the interference judgment threshold. It is the same. The process of reflecting the result of the radio channel assignment process is performed according to a communication protocol used for communication between the base stations 402-1 and 402-2 and the radio terminals 403-1 to 403-5.

  In the communication system of the present embodiment, the timing for performing the radio channel assignment process and the process for reflecting the result of the radio channel assignment process may be the timing shown in the second embodiment.

  As described above, the radio channel assignment processing described in the first embodiment is not limited to a multi-hop network, but a range in which direct communication can be performed with a base station that is a parent station device such as a base station and a radio terminal It can also be applied to a communication system defined as Thereby, the freedom degree of arrangement | positioning of a base station and arrangement | positioning of a radio channel can be raised compared with the channel allocation method on the assumption of a repetition pattern.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Frequency allocation apparatus, 2 Management server, 3 Core communication network, 4,4-1,4-2 Radio | wireless master station, 5,5-1 to 5-M, 5-101 to 5-L Wireless terminal, 6-1 -6-14, 60-1, 60-2 cell, 7 smart meter, 8 wireless communication unit, 9 power meter, 11 interference relationship determination unit, 12 group generation unit, 13 channel allocation unit, 14, 22, 105 communication 15, 23, 44, 53, 103 storage unit, 21 management unit, 40, 50 antenna, 41, 51 wireless communication processing unit, 42, 52, 101 control unit, 43 backbone NW communication processing unit, 54 connected device communication Processing unit, 102 input unit, 104 display unit, 106 output unit, 107 system bus.

Claims (13)

An interference relationship determination unit for determining presence or absence of an interference relationship between cells;
Assigning different radio frequency bands to cells determined to be in an interference relationship by the interference relation determining unit, and minimizing the number of radio frequency bands used for assignment, and the number of cells to which a specific radio frequency band is assigned A frequency allocation unit that allocates a radio frequency band for each cell so as to increase,
With
The interference relationship determination unit determines whether or not there is an interference relationship between cells by comparing an inter-cell distance and an interference determination threshold value, and the interference determination threshold value is calculated based on a traffic amount. A frequency allocation device characterized by the above.   The cell is directly connected to a wireless master station corresponding to the cell and each wireless terminal constituting a wireless terminal group that is wirelessly connected to the wireless master station directly or via another wireless terminal. The frequency allocation device according to claim 1, comprising a communicable range.   When n is an integer greater than or equal to 1 and the distance from the radio master station where the number of hops from the radio master station is n hops is the n hop distance, the interference determination threshold is the n hop distance The frequency allocation apparatus according to claim 2, wherein the frequency allocation apparatus is doubled. A group generation unit that groups cells so that one group including cells determined to be in an interference relationship with each other by the interference relationship determination unit;
With
The frequency allocating unit allocates different radio frequency bands to cells determined to be in an interference relationship by the interference relationship determining unit on a group basis, and minimizes the number of radio frequency bands used for allocation, and a specific radio The frequency allocation apparatus according to any one of claims 1 to 3, wherein a radio frequency band is allocated to a cell in a group so that a number of cells to which a frequency band is allocated increases.   The frequency allocating unit uses a radio frequency band having the youngest identification number among radio frequency bands excluding radio frequency bands already allocated to cells in an interference relationship for cell allocation. Item 5. The frequency allocation device according to any one of Items 1 to 4. An interference relationship determination unit for determining presence or absence of an interference relationship between cells;
Assigning different radio frequency bands to cells determined to be in an interference relationship by the interference relation determining unit, and minimizing the number of radio frequency bands used for assignment, and the number of cells to which a specific radio frequency band is assigned A radio frequency band is assigned to each cell so that the number is increased, and after this assignment, a radio frequency band having a lower identification number is assigned as the number of arrangements, which is the number of cells to which the radio frequency band is assigned, is increased. A frequency allocation apparatus characterized by changing a radio frequency band to be allocated.   Assign different radio frequency bands to cells determined to be in an interference relationship, minimize the number of radio frequency bands used for assignment, and increase the number of cells to which a specific radio frequency band is assigned. A radio frequency band is assigned to a radio frequency band, and after this assignment, a radio frequency band having a lower identification number is assigned as the number of arrangements, which is the number of cells to which the radio frequency band is assigned, increases for each radio frequency band. A management apparatus which notifies a radio master station corresponding to a cell of a radio frequency band allocated to the cell based on an allocation result whose band has been changed.   Assign different radio frequency bands to cells determined to be in an interference relationship, minimize the number of radio frequency bands used for assignment, and increase the number of cells to which a specific radio frequency band is assigned. The radio frequency band assigned to the cell is notified to the radio master station corresponding to the cell based on the assignment result in which the radio frequency band is assigned to the cell, and the traffic is handled when the traffic volume exceeds the threshold value. A management apparatus that notifies an assigned frequency band assigned to the cell to a wireless master station. A communication processing unit operable in a plurality of radio frequency bands;
Assign different radio frequency bands to cells determined to be in an interference relationship, minimize the number of radio frequency bands used for assignment, and increase the number of cells to which a specific radio frequency band is assigned. A radio frequency band is assigned to a radio frequency band, and after this assignment, a radio frequency band having a lower identification number is assigned as the number of arrangements, which is the number of cells to which the radio frequency band is assigned, increases for each radio frequency band. A control unit for instructing the communication processing unit to operate in the radio frequency band notified to the local station based on the allocation result whose band has been changed;
A radio master station comprising: Assign different radio frequency bands to cells determined to be in an interference relationship, minimize the number of radio frequency bands used for assignment, and increase the number of cells to which a specific radio frequency band is assigned. A radio frequency band is assigned to a radio frequency band, and after this assignment, a radio frequency band having a lower identification number is assigned as the number of arrangements, which is the number of cells to which the radio frequency band is assigned, increases for each radio frequency band. A radio terminal that receives a radio frequency band allocated based on an allocation result whose band has been changed from a radio master station,
A communication processing unit operable in a plurality of radio frequency bands;
A control unit that instructs the communication processing unit to operate in a radio frequency band notified from the wireless master station;
A wireless terminal comprising: A communication system comprising a management device, a wireless master station, and a wireless terminal,
The management apparatus allocates different radio frequency bands to cells determined to have an interference relationship, minimizes the number of radio frequency bands used for allocation, and increases the number of cells to which a specific radio frequency band is allocated. A radio frequency band is assigned to each cell so that, after this assignment, a radio frequency band with a lower identification number is assigned as the number of arrangements, which is the number of cells to which the radio frequency band is assigned for each radio frequency band, increases. A communication system characterized by notifying the radio master station corresponding to a cell of the radio frequency band assigned to the cell based on the assignment result of changing the assigned radio frequency band. A communication system comprising a management device, a wireless master station, and a wireless terminal,
The management apparatus allocates different radio frequency bands to cells determined to have an interference relationship, minimizes the number of radio frequency bands used for allocation, and increases the number of cells to which a specific radio frequency band is allocated. Based on the allocation result in which a radio frequency band is allocated for each cell, the radio master station corresponding to the cell is notified of the radio frequency band allocated to the cell, and the radio master station is in an initial state. Use a specific radio frequency band for communication,
The management device notifies the assigned frequency assigned to the cell to the radio master station corresponding to the cell when the traffic volume exceeds a threshold value. A first step in which the frequency allocation device determines whether there is an interference relationship between cells;
The frequency allocation apparatus allocates different radio frequency bands to the cells determined to be in an interference relationship in the first step, and the number of radio frequency bands used for allocation is minimized, and a specific radio frequency band is A second step of allocating radio frequency bands for each cell so that the number of allocated cells is large;
Radio frequency assigned by the frequency allocation device so that a radio frequency band having a lower identification number is allocated as the number of arrangements, which is the number of cells to which the radio frequency band is allocated, increases for each radio frequency band after the second step. A third step of changing the band;
A frequency allocation method including:

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