JP2014207556A - Radio communications system, channel allocation method, and channel changeover method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for rapidly allocating a channel according to the maximum possible transmission power and means for enabling recovery of communication even if communication is not possible on a channel after a channel changeover, in a radio communication system using a white space.SOLUTION: A radio communications system for performing radio communication using a plurality of frequencies by a base station device and a plurality of pieces of customer premises equipment includes a base station device having a plurality of first radio transmission and reception units and a first frequency management unit for managing channels, and customer premises equipment having a second radio transmission and reception unit and a second frequency management unit. The first frequency management unit outputs a channel changeover directions to the customer premises equipment based on channel renewal information from a database or connection information from the customer premises equipment.

Description

  The present invention uses a radio wave flexibly while sufficiently avoiding an influence on a frequency sharing type radio access system (dynamic spectrum access) and existing business to perform radio communication while switching a plurality of frequencies having different usage conditions. The present invention relates to a technique for simultaneously using a plurality of channels in a white space-based wireless communication system.

  The progress of the information society in recent years has been remarkably remarkable, and as a communication method in many information communication devices and services, wireless communication is often used in addition to wired communication. Along with this, the demand for radio frequency, which is a finite resource, is constantly increasing, and the depletion of allocatable frequencies has become a major problem in countries around the world. In general, a frequency is license managed by the country, and only those who are assigned a license can use the frequency under strict control at a specific location and time. However, in order to meet the frequency demand that is expected to continue to increase in the future, there is a need for a new frequency utilization method that is not confined to the conventional utilization method.

  Therefore, in recent years, as a new frequency utilization method to solve the frequency depletion problem, a method that uses a frequency band (white space) that has not been used spatially and temporally even though it has already been allocated has been studied. Has been. For example, a licensed user (hereinafter referred to as “primary user”) sufficiently avoids the influence (interference) on the frequency usage of the existing system, while the unlicensed user (hereinafter referred to as “secondary user”). Research and development of a cognitive wireless communication system in which a user (referred to as “user”) uses a white space flexibly is performed (for example, Non-Patent Document 1).

For example, in a wireless communication system using white space, which is standardized by IEEE802.22, each wireless station accesses a database (DB: Database) on an IP network to obtain its own location information. Based on the transmittable channel list (available channel list) and the maximum transmittable power are obtained. The available channel list is collectively managed while being updated as needed by a spectrum manager (SM) in a base station (BS) which is a master device. Then, the BS determines, from the available channels based on the available channel list and the maximum transmittable power information of each channel, a channel that can maximize the quality of its communication service as an operation channel (channel used for communication). Communicate with a terminal (CPE: Customer Premises Equipment) such as a slave station or a mobile phone installed in the BS within the service range (cell) of the BS. Also, the CPE can acquire its own available channel list and maximum transmittable power, and the CPE that is the slave device makes an information acquisition request to the SM of the BS to acquire information, thereby obtaining a primary user. In addition to avoiding the impact on channel usage, secondary user communication is also realized. Also, since DB information (usage conditions such as available channel list and maximum transmittable power) is updated from time to time according to the usage status of primary users, wireless systems using white space such as IEEE 802.22 DB information is updated by DB notification or information notification (push transmission) from DB, and it has a function to maximize its communication service while switching the operation channel and avoiding the influence on the primary user. ing.
The BS and CPE are obtained from a resource manager (RM) that notifies channel availability information in consideration of the influence (interference) between secondary users as well as primary users in addition to DB access. It is also possible to determine the available channel and the maximum transmittable power according to the information, which can further increase the frequency utilization efficiency.

Koji Fujii, “Cognitive Radio: Core Technology for White Space Utilization, Eliminating Use of Radio Waves”, [online], Rick Telecom, [Search June 9, 2011], Internet <URL: http: // businesnetwork. jp / tabid / 65 / artid / 110 / page / 1 / Default. aspx> IEEE Std 802.22-2011, 1 July 2011, Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layers (PHY) Specifiers: Politics:

One of the purposes of a wireless system using white space is to provide a wireless broadband communication service to a CPE by long-distance wireless transmission. For this reason, it is conceivable that the maximum transmittable power is different for each wireless station. In order to provide a higher-speed communication service, it is natural that IEEE 802.22 is developed and the BS simultaneously uses a plurality of channels (multi-channel). However, although Non-Patent Document 2 defines channel operation start means, channel switching means, and operation stop means, operation channel determination means such as which channel is operated and which channel is assigned to CPE and channel assignment determination. No means are specified. In addition, since it is not known whether the communication can be continued in the switching destination channel until the actual switching is performed, the CPE that has been communicable until the channel switching up to now can limit the maximum transmittable power and the channel propagation characteristics. There may be problems such as communication being disabled due to the difference, and access concentrated on a specific channel when the BS operates a plurality of channels. Further, when one channel is assigned to one CPE that can be used for N channels (candidates for operation), including the option of not allocating channels, channel assignment to M CPEs is ^{MN + 1} assignments. Therefore, when many CPEs are connected, a method for performing channel selection and channel assignment at high speed is also necessary.

  Therefore, according to the present invention, in a wireless communication system using a white space, a means for performing channel assignment at high speed in consideration of the maximum transmittable power and communication can be restored even if communication cannot be performed on the switching destination channel. It aims at providing the means for doing. The present invention is particularly suitable for a wireless communication system using a white space. However, the present invention may be a system that does not use a white space, obtains channel availability and usage conditions from a DB or RM, and sets a plurality of channels. The present invention can be applied to any wireless communication system that performs dynamic spectrum access such that communication is performed while switching.

  The wireless communication system of the present invention is a wireless communication system in which a base station device and a plurality of terminal station devices perform wireless communication using a plurality of frequencies, and the base station device includes a plurality of first wireless transmission / reception units, A first frequency management unit for managing a channel, the terminal station apparatus includes a second radio transmission / reception unit and a second frequency management unit, and the first frequency management unit is configured to receive channel update information from a database or A channel switching instruction is issued to the terminal station based on connection information from the terminal station apparatus.

  A channel allocation method for a radio communication system according to the present invention is a channel allocation method for a radio communication system in which a base station apparatus and a plurality of terminal station apparatuses perform radio communication using a plurality of frequencies. The channel assignment is calculated based on the channel update information or the connection information from the terminal station, and a channel assignment instruction is transmitted to the terminal station apparatus.

  A channel switching method for a wireless communication system according to the present invention is a channel switching method for a wireless communication system in which a base station device and a plurality of terminal station devices perform wireless communication using a plurality of frequencies. A channel switching instruction is transmitted to the terminal station apparatus based on the channel update information or connection failure information from the terminal station.

  The radio communication system according to the present invention includes a base station device that obtains information on usage conditions of available channels and maximum transmittable power from a database or frequency management unit, and information or commands from the database or frequency management unit. When the availability of the operation channel of the device or the use condition of the maximum transmittable power is updated, only the terminal station device connected to the operation channel recalculates the channel assignment as a channel change candidate, and the recalculation Means is provided for instructing the terminal station to switch or disconnect the channel based on the result.

  In the wireless communication system of the present invention, when a notification of failure in connection of the switching destination channel is received from the terminal station device to which the base station device has issued the channel switching command in the switching source channel, the terminal station device is switched to the connection. It comprises means for excluding failed channels and recalculating channel assignment and instructing channel switching or disconnection again based on the recalculation results.

  The wireless communication system of the present invention includes a means for a base station apparatus to acquire information on usage conditions of available channels and maximum transmittable power from a database or a frequency management unit, means for communicating according to the acquired usage conditions, It comprises means for switching the frequency according to a command from the station apparatus, and means for returning to the original channel and transmitting a connection failure notification when communication cannot be established at the commanded channel switching destination.

  The radio communication system according to the present invention is the above-described radio communication system, and recalculation of channel assignment in the base station apparatus depends on an attenuation factor depending on a frequency of an operating channel and a frequency of a switching destination channel. The CNR of the switching destination using the ratio of the attenuation rate, the ratio of the current transmission power and the maximum transmittable power of the switching destination, and the current carrier power-to-noise power ratio (CNR). And a process of deriving a transmission rate corresponding to the received CNR and evaluating QoS.

  According to one aspect of the present invention, in a wireless communication system that performs dynamic spectrum access, it is possible to find the most suitable channel among communicable channels even when it is unclear whether communication can be continued in the switching destination channel. Furthermore, the channel allocation result can be calculated at a high speed and the frequency utilization efficiency can be increased.

It is a figure which shows an example of the whole structure of the radio | wireless communications system which concerns on this embodiment of this invention. It is a block diagram for demonstrating the base station apparatus and terminal station apparatus which are one Example of this invention. It is a sequence diagram for demonstrating operation | movement of the radio | wireless communications system which is one Example of this invention. It is a sequence diagram for demonstrating operation | movement when communication connection fails in the radio | wireless communications system which is one Example of this invention. It is a sequence diagram for demonstrating the detailed operation | movement of the radio | wireless communications system which is one Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same parts as those in the other drawings are denoted by the same reference numerals.

(Outline of wireless communication system)
FIG. 1 is a diagram illustrating an example of the overall configuration of a wireless communication system according to the present embodiment. This wireless communication system assumes application (revision) to IEEE802.22, and the basic configuration is the same as the conventional one. However, the base station apparatus (BS, Base Station) 1 and the terminal station apparatuses (CPE, Customer Premises Equipment) 2 and 3 have a configuration different from those of the prior art, such as having a function of transmitting and receiving simultaneously on a plurality of channels.
A base station apparatus (BS) 1 is connected to a database (DB) and a resource manager (RM) 4 via a network 5.
The base station device (BS) 1 and the terminal station devices (CPE) 2 and 3 may cause interference between the primary system transceiver 6 and the primary / secondary system, and may be hindered from being connected to a specific channel.
In the present invention, BS1 and CPE2 and 3 are obtained from a resource manager (RM) that notifies channel usable information in consideration of the influence (interference) between secondary users as well as primary users in addition to DB access. It is also possible to determine the available channel and the maximum transmittable power according to the information to be obtained, thereby further improving the frequency utilization efficiency.

(Specific configuration example of base station apparatus (BS) and terminal station apparatus (CPE))
FIG. 2 is a block diagram for explaining a base station apparatus and a terminal station apparatus according to an embodiment of the present invention.
In FIG. 2, BS1 includes a radio transmission / reception unit (TRX) 110. The TRX 110 includes an antenna 101, frequency conversion from a baseband (BB, Baseband) to a radio frequency (RF) band, and a radio frequency band. RF unit 102 that performs frequency conversion from baseband to baseband, signal amplification, etc., transmission / reception signal processing unit 103 that performs error correction encoding / decoding processing and modulation / demodulation processing, and a wireless device that performs channel control, transmission / reception timing control, and packet transmission A MAC (Medium Access Control) processing unit 104 for adding an ID for identifying the mobile station and recognizing the transmission source wireless device.
In addition to this, the BS 1 is a sensing unit that performs spectrum sensing signal processing to determine whether there is a wireless system using a channel and an I / F unit 105 that serves as an interface with a backhaul line, a personal computer, a router, and the like. 106, a frequency management unit (SM) 107 that stores and manages channels that can be used as white space, a main control unit 108 that manages and controls the entire radio, an external device such as a backhaul line, a personal computer and a router, and an external device A connection terminal 109 for connecting to a network is provided.

The main control unit 108 can be constituted by, for example, a processor, a data storage area defined on the memory, and software. The transmission / reception signal processing unit 103, the MAC processing unit 104, the sensing unit 106, and the frequency management unit 107 are The program executed by the main control unit 108 can be replaced.
The TRX 110 may include a plurality of hardware units so that a plurality of frequencies can be used simultaneously. The antenna 101, the RF unit 102, the transmission / reception signal processing unit 103, and the MAC processing unit 104 that constitute the TRX 110 have one function. A part or all of them may be divided into a plurality of pieces of hardware. A plurality of hardware may be centrally controlled by the main control unit 108.

  The function of the frequency management unit 107 differs between BS1 and CPE. The frequency management unit of BS 1 stores and manages the available channels for each CPE connected to its own BS, stores and manages the maximum transmittable power for each channel and the available time limit for each channel, and performs maximum transmission. The channel allocation calculation is performed to determine which channel is used so that communication can be performed below the available power and which channel is allocated to which CPE. The frequency management unit of the CPE performs storage management of the maximum transmittable power of each channel and the usable time limit of each channel in addition to storing and managing the channels that can be used by the CPE.

(Operation of wireless communication system)
Hereinafter, the operation of the radio communication system in the case where the BS 1 includes a plurality of TRXs 110 and the CPE includes a single TRX will be described with reference to FIGS. 3 and 4. FIG. 3 shows an example when the channel switching command from the BS 1 to the CPE 2 is successful. FIG. 4 shows an example of the case where the channel switching command from the BS 1 to the CPE 2 fails. Note that this embodiment is merely one aspect, and the utility of the present invention can be obtained by the same sequence regardless of whether the BS 1 and the CPE 2 include a single TRX 110 or a plurality of TRXs 110.

(Operation example when channel switching is successful)
FIG. 3 is a sequence diagram in which BS1 includes a plurality of TRXs 110 and instructs CPE2 to perform channel switching, and shows an example in which the channel switching instruction to CPE2 by BS1 is successful.
As a precondition of the present embodiment, TRX # 1 of BS1 and TRX of CPE2 perform communication using channel #x.

  First, at step 301, the SM of BS1 receives the usage conditions such as the available channel list and the maximum transmittable power information updated from the DB or RM. When the information about CPE2 has been updated, the SM of BS1 notifies the updated CPE2 of the latest information received. In this embodiment, the SM of BS1 notifies the TRX # 1 of the update information (302), transmits it to the TRX of CPE2 using the channel #x (303), and notifies the SM of the CPE2 of the information. (304). The notification of update information from the DB or RM may be a push transmission from the DB or RM, or may be made as a response to an information acquisition request from the BS1 or CPE2.

  In Step 305, the SM of BS1 that has received the update information performs a calculation for optimizing the channel assignment. There are various criteria for the optimality of channel assignment. Examples of the criteria include (1) guaranteeing a minimum transmission rate (service quality: QoS), and (2) maximizing the transmission rate of the entire system. (3) A combination of (1) and (2) is conceivable. (Details will be described later)

  The SM of BS1 transmits a switching command transmission instruction to TRX # 1 including the switching destination channel and the time limit until the switching to CPE2 that is determined to require channel switching as a result of the channel allocation calculation (306). ), TRX # 1 transmits a channel switching command message to channel #y using channel #x to TRX of CPE2 (309). The TRX of CPE2 notifies the received message to the SM (310), and the SM confirms the switching destination channel and transmits a channel switching command to the TRX so as not to exceed the maximum transmittable power (311).

  The SM of BS1 sets the switching waiting timer of CPE2 that has issued the channel switching command (307), and enters the switching waiting state (308).

  The TRX of the CPE 2 executes channel switching in accordance with the channel switching command from the SM (312), and when the TRX channel switching (such as hardware Phase Locked Loop lock) is completed, a switch completion notification is transmitted to the SM (313). In this embodiment, switching from channel #x during communication to channel #y indicated in the switching command message is shown.

  In step 314, processing for initial connection is performed on channel #y after switching. (In this embodiment, since TRX # n of BS1 is operating channel #y, TRX of CPE2 tries to connect to TRX # n of BS1.) In the initial connection processing, BS1 preamble acquisition and ranging Processing such as adjustment of transmission timing, frequency and transmission power, registration, and the like are performed, and during this time, communication is performed a plurality of times between BS1 and CPE2.

When receiving a notification of successful connection (registration success) from BS1, the TRX of CPE2 notifies the SM that the connection has been established (connection establishment notification 1) (315).
The TRX # n of the BS notifies the SM that the CPE channel switching has succeeded (connection establishment notification 2) (317), and the SM stops the switching waiting timer and completes the channel assignment processing (318).
In step 316, the TRX of CPE2 starts communication on channel #y.

(Operation example when channel switching fails)
FIG. 4 shows an example of a case where the channel switching command from the BS 1 to the CPE 2 fails.
Steps 301 to 314 are the same as in the example of FIG.

  As step 314, TRX # n of BS1 and TRX of CPE2 perform processing for initial connection on channel #y after switching. In this embodiment, initial connection processing such as BS1 preamble acquisition, ranging transmission timing, frequency, transmission power adjustment and registration processing is broken in the middle due to a packet error, etc., and BS1 notifies the connection success. If not received (connection establishment failed) (415), the TRX of CPE2 notifies the SM that connection establishment has failed (connection failure notification 1) (416). In response, the SM sends a channel switch command to the TRX to return to the original operation channel #x (417), and the TRX switches to the channel #x (418). Thereafter, when the channel switching to the channel #x is completed, the TRX transmits a switching completion notification to the SM (419).

In step 420, TRX transmits connection failure notification 2 to channel TRX # 1 of BS1 using channel #x.
The TRX # 1 of the BS 1 that has received the connection failure notification 2 notifies the SM of the BS 1 that the CPE 2 has failed to connect (connection failure notification 3) (421), and stops the switching wait timer (422).
In step 423, TRX of CPE2 starts communication on channel #x.

In step 424, the SM of BS1 that has received the connection failure notification returns to the processing in step 305 and recalculates the channel assignment. At this time, allocation of channels that have already failed to be connected is excluded, and the switching destination channel is calculated.
When a new switching destination channel is determined, the processing after step 306 is executed again, and channel switching is attempted. The above process is repeated until the channel is successfully switched or there are no channel candidates that can be allocated.

With the above means, in a wireless communication system that performs dynamic spectrum access, even when it is unclear whether or not communication can be continued in a switching destination channel, it is possible to find the most suitable channel among communicable channels.
When the TRX of BS1 switches channels, the TRX switching destination channel is determined by channel allocation calculation, and the switching procedure is performed in the same manner as in conventional techniques such as IEEE 802.22.

(Channel allocation calculation method)
The channel allocation calculation method performed in steps 305 and 316 in FIG. 3 will be described.

ＤＢやＲＭの情報が更新されるたびにＱｏＳの再計算が行われ、最大送信可能電力が制限された場合には、伝送レートが下がるため、ＱｏＳを満たさなくなり、チャネル再割当の対象となる。
なお、Ｒｊは標準規格で定められている変調方式と符号化方式（ＭＣＳ：Modulation and Coding Scheme）ごとの感度を基に決めてもよい。また、Γはシステムオペレータが運用状況に応じて適宜調整してもよい最低保障ＱｏＳの閾値である。なおＢＳはＣＰＥからの制御メッセージを受信することでＣＰＥのＣＮＲや送信電力を知ることが可能である。 (CPE decision criteria for channel assignment)
There are various channel allocation optimality criteria (evaluation functions). Regardless of the optimization criteria, the calculation of the optimal channel allocation is N, and the total number of TRXs of all CPEs is M. In this case, it is determined from the search space of ^{MN + 1} ways (note that there are N + 1 choices per channel because there is an option not to assign a channel), and an evaluation function is calculated for each. Since it is necessary to search for an optimum combination of channel assignments, the execution time becomes enormous as the number of CPEs increases, and the search for the optimum solution becomes difficult. Therefore, in the present invention, channel reassignment is performed only for CPEs in which the current operation channel becomes unusable and CPEs that no longer satisfy the minimum guaranteed QoS, thereby limiting the search space itself to achieve high speed. Determine channel assignment.
In this embodiment, QoS is a transmission rate when communication resources are equally allocated to each CPE. When (Equation 1) is satisfied, the minimum guaranteed QoS of CPE # j is satisfied.

When the DB or RM information is updated, QoS is recalculated. When the maximum transmittable power is limited, the transmission rate is lowered, so that the QoS is not satisfied and the channel is reassigned.
Note that Rj may be determined based on the sensitivity for each modulation scheme and coding scheme (MCS) defined in the standard. Further, Γ is a threshold value of the minimum guaranteed QoS that the system operator may appropriately adjust according to the operation status. The BS can know the CNR and transmission power of the CPE by receiving a control message from the CPE.

(Evaluation function for optimization)
In this embodiment, multi-objective optimization that simultaneously optimizes two problems of maximizing the number of CPEs that satisfy QoS and maximizing the transmission rate of the entire system is performed, and a weighting factor is applied to each optimization item. By setting an evaluation function using (α, β), an item to be emphasized and optimized can be arbitrarily set by a system operator or the like according to the operation status.

According to the above channel allocation calculation method, channels can be allocated at high speed using the criterion of (Equation 1), and a solution that takes into account the CNR of the switching destination can be obtained according to (Equation 5).
Also, in this embodiment, an example in which the CPE holds a single TRX has been shown. However, considering the combination of channels by considering QoS _j and X (QoS _j ) as the sum of TRXs provided by the CPE, It can be easily extended to CPE having multiple TRXs. Note that X of X (QoS _j ) is described as a symbol in which QoS _j is overlined.

Next, the detailed operation of one embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a sequence diagram for explaining the detailed operation of the wireless communication system according to the embodiment of the present invention.
Steps 301 to 314 are the same as in the example of FIGS. 3 and 4.
As step 314, TRX # n of BS1 and TRX # m of CPE2 perform processing for initial connection on channel #y after switching.

The TRXn of the BS1 determines whether or not a communication connection with the TRX # m of the CPE2 has been established in the initial connection processing such as BS1 preamble acquisition, ranging transmission timing, frequency, transmission power adjustment, and registration processing. Determination is made (515), and if established (YES), the process proceeds to step 517, and if not established (NO), the process proceeds to step 516.
In step 516, the TRXn of the BS1 notifies the SM of the BS1 that the connection with the CPE2 has failed (connection failure notification).
In step 517, the TRXn of BS1 notifies the SM of BS1 that the connection with CPE2 has been successful (connection establishment notification).

The TRX # m of the CPE2 determines whether or not the connection with the TRX # n of the BS1 has been established (518). If it has been established (YES), the process proceeds to steps 519 and 520 to establish the connection. If not (NO), the process proceeds to step 520.
In step 519, TRX # m of CPE2 transmits a switch completion notification to SM of CPE2.

The TRX # m of the CPE2 determines whether or not the connection with the TRX # n of the BS1 has failed (520). If the connection is successful (NO), the process proceeds to step 528 and the connection has failed. In the case (YES), the process proceeds to steps 521 and 523.
In step 521, the TRX of CPE2 notifies the SM that connection establishment has failed (connection failure notification). In response, the SM transmits a channel switch command to TRX # m so as to return to the original operation channel #x (522), and TRX # m switches to channel #x (523).

The TRX # m of the CPE2 determines whether or not the connection with the TRXn of the BS1 has been established (524). If it has been established (YES), the process proceeds to steps 527 and 528 and has not been established. In the case (NO), the process proceeds to step 525.
In step 527, TRX # m of CPE2 transmits a switch completion notification to SM of CPE2.
As step 528, TRX # m of CPE2 starts communication on channel #x or channel #y.

As Step 525, TRX # m of CPE2 transmits a connection failure notification to TRX # 1 of BS1 using channel #x.
In step 526, TRX # 1 of BS1 transmits a connection failure notification to SM of BS1 using channel #x.

The SM of BS 1 determines whether or not a connection establishment notification has been received (529), and proceeds to the process in the direction of being received (YES), and proceeds to the process of step 530 if not received (NO). .
The SM of BS1 determines whether or not a notification indicating whether or not the connection has failed has been received (530). If it has been received (YES), the process returns to 305, and if it has not been received (NO) Returns to before step 516.

  According to the present invention, in a wireless communication system that performs dynamic spectrum access, it is possible to find the most suitable channel among communicable channels even when it is unclear whether communication can be continued in the switching destination channel. In addition to calculating the channel assignment result at high speed, the frequency utilization efficiency can be increased.

The radio communication system according to the present embodiment is particularly suitable for the radio communication system defined by IEEE802.22, but is not limited thereto.
It should be noted that the scope of the present invention is not limited to the illustrated and described exemplary embodiments, but includes all embodiments that provide the same effects as those intended by the present invention. Further, the scope of the invention can be defined by any desired combination of particular features among all the disclosed features.

  1: base station device, 2, 3: terminal station device, 4: database and resource manager, 5: network, 6: primary system transceiver, 110: wireless transceiver, 101: antenna, 102: RF unit, 103: transmission / reception Signal processing unit 104: MAC processing unit 105: I / F unit 106: Sensing unit 107: Frequency management unit 108: Main control unit 109: Connection terminal

Claims (3)

A wireless communication system in which a base station device and a plurality of terminal station devices perform wireless communication using a plurality of frequencies,
The base station apparatus includes a plurality of first radio transmission / reception units and a first frequency management unit that manages channels,
The terminal station apparatus includes a second radio transmission / reception unit and a second frequency management unit,
The wireless communication system, wherein the first frequency management unit issues a channel switching instruction to the terminal station apparatus based on channel update information from a database or connection information from the terminal station apparatus. In a channel assignment method for a wireless communication system in which a base station device and a plurality of terminal station devices perform wireless communication using a plurality of frequencies,
The base station apparatus calculates a channel assignment based on channel update information from a database or connection information from the terminal station, and transmits a channel assignment instruction to the terminal station apparatus. The channel assignment method of the system. In a channel switching method of a wireless communication system in which a base station device and a plurality of terminal station devices perform wireless communication using a plurality of frequencies,
The base station apparatus transmits a channel switching instruction to the terminal station apparatus based on channel update information from a database or connection failure information from the terminal station apparatus. .

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