JP5317877B2 - Communication system, base station, and communication method - Google Patents

Description

  The present invention relates to a communication system, a base station, and a communication method using a wireless broadband system.

  In recent years, broadband communication networks such as the Internet have been developed. As means for realizing this, a wired broadband system using a wired connection such as FTTH (Fiber To The Home) and ADSL (Asymmetric Digital Subscriber Line), and wireless communication represented by Bluetooth (registered trademark), ZigBee, WiMAX, etc. Wireless broadband systems through the Internet are being built and used.

  In such a broadband system, particularly a wireless broadband system, a technology that enables optimal communication for a user using a wireless terminal has been proposed.

  For example, techniques such as a modulation method selection method when transmitting and receiving data, a buffer size, and sharing of radio resources when the remaining radio resources are small have been proposed.

  In addition, a technique has been proposed in which priority is set for each wireless terminal according to the contract contents of the user who uses the wireless terminal and the communication status of the wireless terminal, and wireless resources are allocated according to the priority ( For example, see Patent Document 1).

JP-A-2005-45561

  The technique described above is executed in a radio base station or the like using a certain selection criterion or information related to the selection criterion. The selection criteria and information are set based on the communication form and communication situation assumed when designing the wireless communication system. During operation after setting, when performing wireless communication, it is applied to all wireless terminals based on a fixed selection criterion and the selection criterion, and used for setting priority and allocating wireless resources, etc. become.

  For this reason, the priority set using pre-defined criteria and information, and radio resource allocation according to the priority are performed, so settings (adjustments) according to individual users who use the radio terminal Cannot be performed and the user needs may not be met.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a service that satisfies the needs of individual users who use a wireless terminal and to perform an operation suitable for the service provision. It is to provide a possible communication system, base station, and communication method.

  To achieve the above object, the present invention provides a communication system (communication system) having a base station (base station 100) that communicates with a wireless terminal and a management server (management server 200) that can communicate with the base station. 10), in response to a connection request from the wireless terminal, the base station requests an information requesting unit (setting unit 181) that requests the management server for selection criterion information regarding resource allocation to the wireless terminal, Information acquisition means (wired communication unit 106) for acquiring selection criterion information about the wireless terminal from a management server, resource status grasping means (creating unit 182) for grasping the resource status (wireless resource management information) in the base station, Allocation information (user management) for allocating resources to the wireless terminal in accordance with the grasped resource status and the selection criterion information An allocation information creating means (creating unit 182) for creating information, and the management server relates to a receiving means (control unit 202) for accepting a request for the selection criterion information from the base station, and to the wireless terminal A transmission unit (wired communication unit 201) for grasping selection criterion information and transmitting the grasped selection criterion information regarding the wireless terminal to the base station, wherein the selection criterion information includes a selection criterion regarding a plurality of items; And the priority order of the selection criteria.

  According to the present invention, allocation information to be allocated to a wireless terminal is created using selection criteria regarding a plurality of items and selection criteria information including the priority order, so that a service that satisfies the needs of individual users who use the wireless terminal In addition, it is possible to perform operations suitable for the service provision.

  In the communication system according to the present invention, the base station may select the higher priority selection criterion if the allocation information creation means of the base station does not satisfy all the selection criteria included in the selection criterion information. It is characterized by creating allocation information for performing resource allocation satisfying the above.

  According to the present invention, it is possible to provide a minimum service desired by a user by performing resource allocation that satisfies at least a selection criterion having a high priority.

  The communication system according to the present invention further comprises management means for managing resource information that can be allocated to radio terminals in the base station, wherein the resource status grasping means is the resource information managed by the management means. To grasp the resource status.

  Further, the base station of the communication system according to the present invention includes a communication status grasping means for grasping a communication status after starting communication with the radio terminal, and a resource to the radio terminal based on the communication status grasped after the communication starts. And adjusting means for adjusting the allocation.

  In order to achieve the above object, the present invention provides a base station of a communication system having a base station that communicates with a wireless terminal and a management server that can communicate with the base station, the connection from the wireless terminal In response to the request, information request means for requesting the management server for selection criterion information regarding resource allocation to the wireless terminal, information acquisition means for acquiring selection criterion information regarding the wireless terminal from the management server, and the base Resource status grasping means for grasping a resource situation in a station, and allocation information creating means for creating assignment information for allocating resources to the wireless terminal according to the grasped resource situation and the selection criterion information, The selection criterion information includes a selection criterion regarding a plurality of items and a priority order of the selection criterion.

  In order to achieve the above object, the present invention provides a communication method of a communication system including a base station that performs communication with a wireless terminal and a management server that can communicate with the base station, wherein the base station In response to a connection request from a wireless terminal, requesting the management server for selection criterion information regarding resource allocation to the wireless terminal, and the management server accepting a request for the selection criterion information from the base station A step of grasping selection criterion information relating to the wireless terminal, and transmitting the grasped selection criterion information to the base station; and the base station acquires selection criterion information relating to the wireless terminal from the management server. According to the step, the step of grasping the resource situation in the base station, the grasped resource situation, and the selection criterion information, Comprising the steps of creating allocation information for allocating a resource to the line terminal, and the selection criterion information includes selection criteria for multiple items, the priority of the selected criteria, characterized in that.

It is possible to provide a service that satisfies the needs of individual users who use wireless terminals and to perform operations suitable for the service provision.

1 is a schematic configuration diagram illustrating a communication system according to an embodiment of the present invention. It is the functional block diagram which showed the structure of the base station of the communication system which concerns on embodiment of this invention, and a management server. It is the figure which showed the table of the selection reference | standard information which a management server memorize | stores in the communication system which concerns on embodiment of this invention, the radio | wireless resource management information which a base station memorize | stores, and user management information. It is the figure which showed the table of the adjusted user management information which the base station memorize | stores in the communication system which concerns on embodiment of this invention. It is the figure which showed the operation | movement at the time of data communication in the communication system which concerns on embodiment of this invention.

Next, an embodiment of the present invention will be described with reference to the drawings.
(1) Configuration of communication system
First, the configuration of the communication system according to the present embodiment will be described.
(1.1) Overall schematic configuration
FIG. 1 is a schematic configuration diagram of a communication system according to the present embodiment. As shown in FIG. 1, the communication system 10 includes a base station 100, a management server 200, a plurality of wireless terminals 300 (300X, 300Y, 300Z), and a wired network 400.
(1.2) Configuration of communication system
FIG. 2 is a functional block diagram illustrating configurations of the base station 100 and the management server 200 included in the communication system according to the present embodiment.
(1.2.1) Configuration of Base Station As shown in FIG. 2, the base station 100 includes an antenna 101, a radio processing unit 102, a signal processing unit 103, a buffer unit 104, an upper layer processing unit 105, and a wired communication unit 106. A storage unit 107 and a control unit 108.

  The wireless processing unit 102 transmits or receives a wireless signal (RF signal) using the antenna 101. The wireless processing unit 102 includes a reception system (LNA, down converter and A / D converter), a transmission system (D / A converter, up converter and power amplifier), and the like.

  The wireless processing unit 102 converts the baseband signal from the signal processing unit 103 into an analog signal at the time of signal transmission. The wireless processing unit 102 up-converts and amplifies the analog signal to generate a wireless signal, and transmits the generated wireless signal from the antenna 101. Further, the radio processing unit 102 controls the transmission power of the radio signal in accordance with an instruction from the control unit 108.

  The radio processing unit 102 converts the radio signal into a baseband signal by amplifying, down-converting, and A / D converting the radio signal from the antenna 101 at the time of signal reception. The baseband signal is input to the signal processing unit 103.

  The signal processing unit 103 demodulates user data from the baseband signal and performs error correction decoding at the time of signal reception. The signal processing unit 103 modulates user data and performs error correction coding using a modulation class instructed by the control unit 108 during signal transmission. Further, the signal processing unit 103 measures reception quality such as SNR and CRC in the uplink UL at the time of signal reception.

  The buffer unit 104 temporarily stores user data in order to control the order of received user data at the time of signal reception. The buffer unit 104 temporarily stores the user data at the time of signal transmission until the transmission of the user data is completed.

  The upper layer processing unit 105 generates user data. For example, the upper layer processing unit 105 executes a communication protocol such as RTP (Transport Protocol for Real-Time Applications: RFC 1889) / UDP (User Datagram Protocol: RFC 768) / IP (Internet Protocol: RFC 791).

  The wired communication unit 106 transmits or receives data with the management server 200 via the network 400.

  The storage unit 107 stores various information necessary for the operation of the control unit 108. The storage unit 107 stores communication management information, radio resource management information, and user management information.

  The communication management information is information related to the current wireless communication status in the base station 100. This information includes, for example, reception quality such as RSSI of downlink DL notified by each radio terminal 300, reception quality of uplink UL of each radio terminal 300 measured by the signal processing unit 103, and the like. In addition, for example, the distance between the base station 100 and the terminal 300, the communication data amount, the communication frequency, and the like may be included. These pieces of communication management information are acquired and updated every predetermined time.

  The radio resource management information is information for managing radio resources that can be provided by the base station 100. This information includes the number of radio communication channels that can be allocated, the remaining expansion buffer amount that can be allocated, the number of radio terminals that can be allocated with priority, and the like. This radio resource management information is updated according to the creation of user management information for the radio terminal 300.

  The user management information manages, for each wireless terminal 300, information set in the wireless terminal 300 that is currently communicating and the wireless terminal 300 that has connected to the base station 100 and has performed wireless communication in the past. Information. As this user management information, setting information corresponding to the service requested by each wireless terminal 300 is created using the wireless resource management information.

  The control unit 108 includes a setting unit 181, a creation unit 182, and an update unit 183.

  When the setting unit 181 detects a connection request from the wireless terminal 300, the setting unit 181 performs a process of requesting selection criterion information from the management server 200. In addition, the setting unit 181 performs setting related to wireless communication based on the user management information of the wireless terminal 300 stored in the storage unit 107 for the wireless terminal 300 that has made a connection request. Furthermore, with the update (adjustment) of user management information of the wireless terminal 300, the setting unit 181 updates settings related to wireless communication.

  The creation unit 182 creates user management information used when wireless communication is performed with the wireless terminal 300 that has made a connection request. The creation unit 182 creates user management information using the radio resource management information stored in the storage unit 107 and the selection criterion information of the radio terminal 300 acquired from the management server 200. The creation unit 182 also updates the radio resource management information used for creation after creating the user management information. Further, user management information for each wireless terminal 300 is created according to the priority order included in the selection criterion information. Details regarding creation of user management information according to priority will be described later.

  The update unit 183 updates (adjusts) the user management information stored in the storage unit 107 in response to the update of the communication management information stored in the storage unit 107.

Note that the control unit 108 also performs automatic retransmission control (ARQ), error detection using CRC, and the like in communication with the wireless terminal 300.
(1.2.2) Management server configuration
As illustrated in FIG. 2, the management server 200 includes a wired communication unit 201, a control unit 202, and a storage unit 203.

  The wired communication unit 201 transmits or receives data with the base station 100 via the network 400.

  When the selection criterion information of the wireless terminal 300 that has made the connection request is requested from the base station 100, the control unit 202 accepts the request. Then, selection criteria information corresponding to the wireless terminal 300 is grasped and processing for transmitting to the base station 100 is executed. When the use registration of the wireless terminal 300 is performed, selection criterion information corresponding to the service content of the use registration is created. When the management server 200 is an authentication server, for example, the control unit 202 may also execute processing such as authentication processing for the wireless terminal 300 that has made a connection request.

The storage unit 203 stores selection criterion information in each wireless terminal 300. The selection criterion information is information indicating a selection criterion when the base station 100 selects and assigns a radio resource corresponding to a service content desired when a user who uses each radio terminal 300 performs use registration. It is. This selection criterion information is updated according to a change in the service content desired by the user.
(2) Creation and update (adjustment) of user management information
Next, creation and updating of user management information in the base station of the communication system according to the present embodiment will be described with reference to FIGS.

  In FIG. 3A, the selection criterion information stored in the storage unit 203 of the management server 200 is set for each wireless terminal 300 (wireless terminals X, Y, and Z), as shown in FIG. It is a figure which shows being managed as a secure table.

  The selection criterion information is used when the base station 100 creates user management information for assigning radio resources to the radio terminal 300. As shown in FIG. 3A, this selection criterion information includes, for example, an extended buffer size for expanding a buffer for temporarily storing user data to be transmitted and received in the buffer unit 104, the base station 100, and the wireless terminal 200. When there is no user data to be transmitted / received at the time of idle (during idle time), the time until TCH (Traffic Channel) is disconnected, or when the base station 100 has a heavy load in wireless communication or the like (for example, when the amount of remaining radio resources is small) Whether to share a wireless channel with another wireless terminal 300, a reference when selecting a modulation method during wireless communication with the wireless terminal 300, a terminal type of the wireless terminal 300, and a priority order for giving priority to each item , Etc. are stored. Among these, the priority order is used when the base station 100 is limited in the amount of radio resources that can be allocated and the base station 100 cannot provide radio resources that satisfy all the criteria. In this case, reassignment of radio resources is performed so that at least the radio resource with the highest priority can be secured.

  This selection criterion information is set according to the service content desired by the user. For example, a user who uses the wireless terminal X can perform higher speed communication when the communication environment is good at the time of use registration. On the other hand, when the communication environment deteriorates, a slight delay occurs or the communication speed is temporary. Suppose you want a service that can be unstable. In this case, as shown in FIG. 3A, for example, the buffer size is expanded by at least M (kB) as the buffer size, S (msec) as the disconnection time, and wireless communication with other wireless terminals 300 Channel sharing is not used, and a modulation scheme of 8QAM (8 Quadrature Amplitude Modulation) or less (a modulation scheme having a communication rate of 8QAM or less) is adopted as a reference for the modulation scheme, and settings are made according to the desired service. . Here, the reference of the modulation scheme at the time of modulation is the upper limit of the settable modulation scheme, that is, the modulation scheme having the highest communication rate of the modulation scheme. If the modulation method is based on the modulation method with the lowest communication rate, the modulation method with the higher communication rate is sequentially performed according to the communication status. Processing to change to a modulation method having a low rate is performed. Thereby, for example, in the wireless terminal 300 used by a user who desires a service with a high communication speed, the stability of the communication speed cannot be maintained, and the desired service cannot be provided. Also, the priority is set in the order of buffer size and disconnection time, with sharing availability being the highest priority. If there is an item for which no selection criterion is set for the wireless terminal 300, a predetermined initial value is set.

  Further, it is assumed that a user who uses the wireless terminal Y desires a service capable of stable communication with little delay even when the communication speed is low at the time of use registration. In this case, as shown in FIG. 3A, for example, the buffer size is extended by at least N (kB), the disconnection time is T (msec), and the radio channel is shared with other radio terminals 300. Adopting a modulation scheme below QPSK (Quadrature Phase Shift Keying) (modulation scheme having a communication rate below the QPSK communication rate) as a modulation scheme reference, and setting according to the desired service Do. The priority order is set in the order of disconnection time and shareability, with the buffer size at the top.

  3B and 3C are diagrams showing tables of radio resource management information for managing radio resources that can be provided by the base station 100. FIG. As described in FIGS. 3B and 3C, the base station 100 manages radio resources that can be allocated to the radio terminal 300, and grasps the current radio resources when creating user management information. To use. As items of the radio resource management information, for example, in the buffer unit 104, the remaining expansion buffer amount that can be allocated to expand the buffer, the number of radio channels that can be allocated to the radio terminal 300, and the highest priority are reliably allocated. Information on the number of remaining wireless terminals, etc. is stored. Note that FIG. 3B shows radio resource management information before creation of user management information for the wireless terminal X, which will be described later, and FIG. 3C shows radio resource management information after creation of user management information for the wireless terminal X.

  3D and 3E are diagrams showing tables of user management information stored in the storage unit 107 of the base station 100. FIG. This user management information is set based on the selection criterion information of each wireless terminal 300 received from the management server 200 and the wireless resource management information stored in the storage unit 107.

  For example, when the above-described wireless terminal X (wireless terminal 300) makes a connection request to the base station 100, the selection criterion information regarding the wireless terminal X acquired from the management server 200 and the wireless resource management stored in the storage unit 107 The creation unit 182 creates user management information related to the wireless terminal X by referring to and comparing the information.

  First, the creation unit 182 creates setting information related to whether or not sharing is possible with the highest priority. For creation, information on whether sharing is possible and the number of remaining radio channels is used. In this case, as shown in FIG. 3B, since the number of remaining radio channels is 1, it is not necessary for the radio terminal X to share a radio channel with other radio terminals 300. Therefore, a radio channel is assigned to the radio terminal X alone. Next, regarding the TCH disconnection time with a high priority, S is compared with the initial disconnection reference time. In this case, since it is larger than the initial value, whether or not the disconnection time requested by the wireless terminal X can be allocated is referred to, or the number of disconnected time securing terminals included in the wireless resource management information is referred. Since the allocation is possible as a result of the reference, the disconnection time S requested by the wireless terminal X is set. Regarding the extended buffer amount having the second highest priority, first, the presence / absence of the request for the extended buffer amount is grasped. If there is a requested extension buffer amount, the requested extension buffer amount M is compared with the remaining extension buffer amount included in the radio resource management information. In this case, since M <L, the requested expansion buffer amount M is allocated to the wireless terminal X. The highest modulation scheme is set as required. Therefore, the user management information in the wireless terminal X is created by the creation unit 182 as shown in FIG. The wireless terminal Z is in wireless communication with the base station 100 before the connection request of the wireless terminal X. Further, after creating the user management information of the wireless terminal X, the creating unit 182 updates the wireless resource information as shown in FIG.

  Next, it is assumed that the wireless terminal Y (wireless terminal 300) requests connection to the base station 100. In this case, the selection criterion information regarding the wireless terminal Y acquired from the management server 200 and the wireless resource management information stored in the storage unit 107 are referred to and compared. Then, the creation unit 182 creates user management information regarding the wireless terminal Y. At this time, in the wireless terminal Y, the extension buffer amount with the highest priority cannot satisfy the extension buffer amount with N> LM. Next, it is impossible to secure the cutting time with the next highest priority. Furthermore, it is assumed that the radio channel with the next highest priority cannot be assigned alone. In this case, since the remaining priority allocation number is 1 in the radio resource management information, it is possible to perform reallocation for securing at least the extended buffer amount having the highest priority in the radio terminal Y. At this time, it is assumed that the priority order of the expansion buffer amount in the wireless terminal Z (wireless terminal 300) currently in communication is the lowest. In this case, the extended buffer of the wireless terminal Z is released, and the opened extended buffer is assigned to the wireless terminal Y. Therefore, the user management information in the wireless terminals Y and Z is created and updated (adjusted) by the creation unit 182 as shown in FIG. The wireless terminal Y is set to an initial value for the disconnection time, and the wireless terminal Y has an expansion buffer amount of 0.

  FIG. 4 is a diagram illustrating adjustment of user management information according to communication management information stored in the storage unit 107 of the base station 100. The communication management information is information for managing the acquired wireless communication status with each wireless terminal 300. Then, the update unit 183 updates (adjusts) the user management information stored in the storage unit 107 according to the acquired wireless communication status.

For example, in the wireless communication between the base station 100 and the wireless terminal X, it is assumed that the wireless communication status is very good from the value of the SNR acquired in the downlink DL. In this case, the updating unit 183 determines that the stability of wireless communication can be ensured even when the modulation method used when transmitting user data to the wireless terminal X has a communication rate higher than 8QAM, for example, 16QAM. Then, the update unit 183 updates the setting of the highest modulation scheme for user management information in the wireless terminal X from 8QAM to 16QAM. In such a situation, when the update unit 183 determines that an error is unlikely to occur in the user data to be transmitted, the update (adjustment) is performed to gradually reduce the reduction of the allocated extension buffer amount. And the setting part 181 performs the setting regarding communication based on the adjusted user management information. By making such adjustments, the radio resource allocation in the base station 100 is adjusted so that the service desired by the user is ensured while the user does not notice that the service has deteriorated. Do. As a result, services desired by more users who use the wireless terminal 300 can be satisfied.
(3) Operation of communication system 10
Next, operations of the base station 100, the management server 200, and the wireless terminal 300 in the communication system 10 according to the present embodiment will be described.
FIG. 5 is a diagram illustrating operations in the base station 100, the management server 200, and the wireless terminal 300.

  In step S51, the radio terminal 300 makes a connection request to the base station 100.

  In step S52, the base station 100 that has received the connection request requests the management server 200 for selection criterion information of the wireless terminal 300 that has requested connection.

  In step S <b> 53, the management server 200 transmits the requested selection criterion information of the wireless terminal 300 to the base station 100.

  In step S54, the base station 100 refers to the selection criterion information of the wireless terminal 300 received from the management server 200 and compares the wireless resource management information.

  In step S55, the base station 100 creates user management information of the wireless terminal 300 according to the reference and comparison results.

  In step S56, the base station 100 and the wireless terminal 300 make settings related to communication based on user management information, and then start transmission / reception of user data.

  In step S57, the base station 100 acquires the communication status with the wireless terminal 300 every predetermined time, and creates and manages it as communication management information.

  In step S58, the base station 100 updates (adjusts) the user management information in the wireless terminal 300 based on the communication management information.

  In step S59, the base station 100 determines whether or not the communication with the radio terminal 300 has ended. If the communication has not ended, the base station 100 proceeds to step S57 again.

In the above-described embodiment, the highest modulation scheme is used for setting the modulation scheme of the selection criterion information in the radio terminal 300, but the present invention is not limited to this, and the SNR reference value when setting the modulation scheme. It may be related to a setting such as changing. Further, each item of selection criterion information and user management information includes information other than that described in the above embodiment.

DESCRIPTION OF SYMBOLS 10 ... Communication system 100 ... Base station 101 ... Antenna 102 ... Wireless processing part 103 ... Signal processing part 104 ... Buffer part 105 ... Upper layer processing part 106 ... Wired communication part 107 ... Memory | storage part 108 DESCRIPTION OF SYMBOLS Control part, 181 ... Setting part, 182 ... Creation part, 183 ... Update part, 200 ... Management server, 201 ... Wired communication part, 202 ... Control part, 203 ... Storage part, 300 ... Wireless terminal, 400 ... Network.

Claims (6)

In a communication system having a base station that communicates with a wireless terminal and a management server that can communicate with the base station,
The base station
In response to a connection request from the wireless terminal, an information requesting unit that requests selection criterion information related to resource allocation to the wireless terminal to the management server;
Information acquisition means for acquiring selection criterion information about the wireless terminal from the management server;
Resource status grasping means for grasping the resource status in the base station;
Allocation information creating means for creating allocation information for allocating resources to the wireless terminal in accordance with the grasped resource status and the selection criterion information;
The management server
Accepting means for accepting a request for the selection criterion information from the base station;
Transmission means for grasping selection criterion information regarding the wireless terminal and transmitting the grasped selection criterion information regarding the wireless terminal to the base station,
The selection criterion information includes a selection criterion regarding a plurality of items and a priority order of the selection criterion.
A communication system characterized by the above. The allocation information creating means of the base station creates allocation information for performing resource allocation that satisfies the selection criterion having a high priority when not satisfying all the selection criteria included in the selection criterion information.
The communication system according to claim 1. The base station
Management means for managing resource information that can be allocated to wireless terminals in the base station, and
The resource status grasping means grasps the resource status from the resource information managed by the management means;
The communication system according to claim 1 or 2. The base station
A communication status grasping means for grasping a communication status after starting communication with the wireless terminal;
Adjusting means for adjusting resource allocation to the wireless terminal based on the communication status obtained after the start of communication;
The communication system according to any one of claims 1 to 3, further comprising: A base station of a communication system having a base station that communicates with a wireless terminal and a management server that can communicate with the base station,
In response to a connection request from the wireless terminal, an information requesting unit that requests selection criterion information related to resource allocation to the wireless terminal to the management server;
Information acquisition means for acquiring selection criterion information about the wireless terminal from the management server;
Resource status grasping means for grasping the resource status in the base station;
Allocation information creating means for creating allocation information for allocating resources to the wireless terminal in accordance with the grasped resource status and the selection criterion information;
The selection criterion information includes a selection criterion regarding a plurality of items and a priority order of the selection criterion.
A base station characterized by that. A communication method of a communication system having a base station that performs communication with a wireless terminal and a management server that can communicate with the base station,
The base station
In response to a connection request from the wireless terminal, requesting the management server for selection criterion information regarding resource allocation to the wireless terminal;
The management server
Receiving a request for the selection criteria information from the base station;
Grasping selection criterion information regarding the wireless terminal, and transmitting the grasped selection criterion information to the base station;
The base station
Obtaining selection criteria information about the wireless terminal from the management server;
Grasping the resource status in the base station;
Creating allocation information for allocating resources to the wireless terminal according to the grasped resource status and the selection criterion information,
The selection criterion information includes a selection criterion regarding a plurality of items and a priority order of the selection criterion.
A communication method characterized by the above.