Terminal, transmission method, and transmission program

Abstract

This terminal comprises a determining unit and a transmitting unit. The determining unit determines a regulation target for transmission power on the basis of a beacon frame. The transmitting unit transmits a first frame at a first frequency band when it has been determined that the regulation target is not a transmission power density, and further transmits a second frame that is a copy of the first frame at a second frequency band while transmitting the first frame at the first frequency band when it has been determined that the regulation target is the transmission power density.

Description

[Technical field]

[0001] The embodiments relate to a terminal, a transmission method, and a transmission program. [Background technology]

[0002] A wireless LAN (Local Area Network) is known as a system for wirelessly connecting a base station and a terminal. With a wireless LAN, a terminal located within the communication area of ​​a base station can access a network via the base station. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE Std 802.11-2016,”19.3.11.12 Non-HT duplicate transmission”, 7 December 2016 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in areas where the base station is far from the terminal, communication between the base station and the terminal becomes unstable. Also, the transmission capability of the terminal is often lower than that of the base station. For this reason, communication is likely to become unstable, especially in the uplink.

[0005] The present invention has been made in light of the above-mentioned circumstances, and an object of the present invention is to provide a stable wireless communication environment in an area where a base station is far from a terminal. [Means for solving the problem]

[0006] A terminal according to an embodiment includes a determination unit and a transmission unit. The determination unit determines a transmission power restriction target based on a beacon frame. When it is determined that the transmission power restriction target is a transmission power density, the transmission unit transmits a first frame in a first frequency band while further transmitting a second frame, which is a copy of the first frame, in a second frequency band. Effect of the Invention

[0007] According to the embodiment, it is possible to provide a stable wireless communication environment in an area where a base station is far from a terminal. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a communication system according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a hardware configuration of the base station according to the embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating an example of a hardware configuration of a terminal according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a format of a MAC frame according to the embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an example of a format of a beacon frame according to the embodiment. [Figure 6] FIG. 6 is a block diagram illustrating an example of a functional configuration of the base station according to the embodiment. [Figure 7] FIG. 7 is a block diagram illustrating an example of a functional configuration of a terminal according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of a transmission power restriction determination operation in the terminal according to the embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of a frequency band control operation in the terminal according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a format of a beacon frame among wireless frames according to the modified example. [Figure 11] FIG. 11 is a flowchart showing an example of a transmission power restriction determination operation in a terminal according to the modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings. In the following description, components having the same functions and configurations are denoted by the same reference numerals.

[0010] 1. Embodiment 1.1 Configuration The configuration of a communication system according to an embodiment will be described.

[0011] 1.1.1 Communication Systems FIG. 1 is a block diagram showing an example of a configuration of a communication system according to an embodiment.

[0012] As shown in FIG. 1, the communication system 1 includes a base station 10, a terminal 20, and a network 30.

[0013] The base station 10 is, for example, an access point of a wireless LAN. The base station 10 is configured to communicate with a server (not shown) on a network 30 via wired or wireless communication. The base station 10 is configured to communicate with a terminal 20 via wireless communication. The communication between the base station 10 and the terminal 20 complies with, for example, the IEEE 802.11 standard.

[0014] The terminal 20 is, for example, a wireless terminal such as a smartphone or a PC (Personal Computer). The terminal 20 may be another electronic device such as an IoT (Internet of Things) device. The terminal 20 can communicate with a server on the network 30 via the base station 10.

[0015] The area in which the terminal 20 can communicate with the base station 10 varies depending on the transmission conditions of the wireless signal transmitted from the terminal 20. For example, areas A1 and A2 are defined that spread around the base station 10. Area A1 is an area in which the terminal 20 can transmit to the base station 10. Area A2 is an area in which the base station 10 can transmit to the terminal 20. Area A2 is wider than area A1 because the base station 10 uses wireless components with higher performance than the terminal 20. When the terminal 20 is located outside area A1 and inside area A2, the terminal 20 can receive wireless signals from the base station 10 but cannot transmit wireless signals to the base station 10. In order to fill such a gap between the base station 10 and the terminal 20, it is desirable that the terminal 20 can change the communication conditions in such a situation so that it can stably communicate with the base station 10.

[0016] 1.1.2 Hardware Configuration Next, the hardware configuration of the base station and the terminal in the communication system according to the embodiment will be described.

[0017] (Base station hardware configuration) FIG. 2 is a block diagram illustrating an example of a hardware configuration of the base station according to the embodiment.

[0018] As shown in FIG. 2, the base station 10 includes, for example, a central processing unit (CPU) 11, a read only memory (ROM) 12, a random access memory (RAM) 13, a wireless communication module 14, and a wired communication module 15.

[0019] The CPU 11 is a processing circuit that controls the overall operation of the base station 10. The ROM 12 is, for example, a non-volatile semiconductor memory. The ROM 12 stores programs and data for controlling the base station 10. The RAM 13 is, for example, a volatile semiconductor memory. The RAM 13 is used as a working area for the CPU 11. The wireless communication module 14 is a circuit used for transmitting and receiving data by wireless signals. The wireless communication module 14 is connected to an antenna. The wired communication module 15 is a circuit used for transmitting and receiving data by wired signals. The wired communication module 15 is connected to a network 30.

[0020] (Device hardware configuration) FIG. 3 is a block diagram illustrating an example of a hardware configuration of a terminal according to the embodiment.

[0021] As shown in FIG. 3, the terminal 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage 26.

[0022] The CPU 21 is a processing circuit that controls the overall operation of the terminal 20. The ROM 22 is, for example, a non-volatile semiconductor memory. The ROM 22 stores programs and data for controlling the terminal 20. The RAM 23 is, for example, a volatile semiconductor memory. The RAM 23 is used as a working area for the CPU 21. The wireless communication module 24 is a circuit used for transmitting and receiving data by wireless signals. The wireless communication module 24 is connected to an antenna. The display 25 is, for example, an LCD (Liquid Crystal Display) or an EL (Electro-Luminescence) display. The display 25 displays a GUI (Graphical User Interface) corresponding to application software, etc. The storage 26 is a non-volatile storage device. The storage 26 stores system software, etc. of the terminal 20.

[0023] 1.1.3 Functional Configuration Next, the functional configuration of the base station and the terminal in the communication system according to the embodiment will be described.

[0024] (Communication Function) The base station 10 and the terminal 20 have a communication function based on, for example, the OSI (Open Systems Interconnection) reference model. In the OSI reference model, the communication function is divided into seven layers (first layer: physical layer, second layer: data link layer, third layer: network layer, fourth layer: transport layer, fifth layer: session layer, sixth layer: presentation layer, seventh layer: application layer). In this specification, the second layer, the data link layer, is used as a reference and the third layer to the seventh layer are called "upper layers". The data link layer includes an LLC (Logical Link Control) layer and a MAC (Media Access Control) layer. In the LLC layer, a DSAP (Destination Service Access Point) header, an SSAP (Source Service Access Point) header, and the like are added to data input from an upper application to generate an LLC packet. In the MAC layer, a MAC header is added to the LLC packet to generate a MAC frame. In the physical layer, a preamble and the like are added to the MAC frame to generate a wireless frame. A radio frame is also called a PPDU (Physical layer (PHY) Protocol Data Unit).

[0025] FIG. 4 is a diagram illustrating an example of a format of a MAC frame generated in the base station and the terminal according to the embodiment.

[0026] As shown in Figure 4, the MAC frame includes a Frame Control field, other control information fields, a Frame Body field, and an FCS (Frame Check Sequence) field. The Frame Control field and other control information fields correspond to the MAC header. The Frame Body field corresponds to the MAC payload. The FCS field is information added to detect frame errors.

[0027] The Frame Control field contains a Type value and a Subtype value.

[0028] The Type value and Subtype value indicate the frame type of the MAC frame. Specifically, for example, a Type value of "00" indicates that the MAC frame is a management frame. A Type value of "01" indicates that the MAC frame is a control frame. A Type value of "11" indicates that the MAC frame is a data frame. The contents of the MAC frame change depending on the combination of the Type value and Subtype value. Specifically, for example, a combination of a Type value of "00" and a Subtype value of "1000" indicates that the management frame is a beacon frame.

[0029] Fig. 5 is a diagram showing an example of a format of a beacon frame according to the embodiment, in which an example of an information element (IE) included in a Frame Body field of a beacon frame is shown.

[0030] As shown in FIG. 5, the beacon frame includes a Country IE and a Power Constraint IE.

[0031] The Country IE is an element that includes information indicating the region and country in which the base station 10 is located, and information indicating the maximum transmission power.

[0032] The Power Constraint IE is an information element that indicates a limit value of the transmission power imposed in the area where the base station 10 is located. The Country IE and Power Constraint IE allow the calculation of the upper limit of transmission power imposed in the area where the base station 10 is located. Specifically, the upper limit of transmission power is "(maximum transmission power in Country IE) - (transmission power limit in Power Constraint IE)". The upper limit of transmission power may differ depending on the object of transmission power regulation. For example, when the object of transmission power regulation is total transmission power, the upper limit of transmission power indicates the upper limit of total transmission power. Also, for example, when the object of transmission power regulation is transmission power density, the upper limit of transmission power indicates the upper limit of transmission power per unit frequency band. The unit frequency band may be in units of channels. The unit frequency band may be in units of subcarriers.

[0033] (Base station functional configuration) FIG. 6 is a block diagram illustrating an example of a functional configuration of the base station according to the embodiment.

[0034] As shown in FIG. 6, the base station 10 functions as a computer including a data processing unit 110, a MAC frame processing unit 120, a management unit 130, a PHY header processing unit 140, a radio signal processing unit 150, and an MCS control unit 160.

[0035] The data processing unit 110 is a functional block that executes processes corresponding to the LLC layer and higher layers. When the base station 10 is a transmitting station, the data processing unit 110 generates a Frame Body field of a data frame based on data received from the network 30, and transmits it to the MAC frame processing unit 120. When the base station 10 is a receiving station, the data processing unit 110 extracts data from the Frame Body field of the data frame received from the MAC frame processing unit 120, and transmits it to the network 30.

[0036] The MAC frame processing unit 120 is a functional block that executes processing corresponding to the MAC layer. When the base station 10 is a transmitting station, the MAC frame processing unit 120 generates a MAC frame based on the Frame Body field received from the data processing unit 110 and the management unit 130. When the base station 10 is a receiving station, the MAC frame processing unit 120 extracts the Frame Body field from the MAC frame received from the PHY header processing unit 140 and transmits it to the data processing unit 110.

[0037] The management unit 130 is a functional block that manages beacon frames. The management unit 130 stores location information 131 and transmission power regulation information 132. The management unit 130 also includes a beacon generation unit 133.

[0038] The location information 131 is information indicating the region and country in which the base station 10 is located.

[0039] The transmission power regulation information 132 is information related to regulations on transmission power imposed in the area where the base station 10 is located. Specifically, the transmission power regulation information 132 includes information indicating whether or not there is a regulation on transmission power. If there is a regulation on transmission power, the transmission power regulation information 132 further includes information identifying the target of the regulation on transmission power.

[0040] For example, when the restriction target is the total transmission power, an upper limit value of the total transmission power is stored as the transmission power restriction information 132. Also, when the restriction target is the transmission power density, an upper limit value of the transmission power per unit frequency band is stored as the transmission power restriction information 132.

[0041] The location information 131 and the transmission power regulation information 132 may be set in advance by an administrator. The transmission power regulation information 132 may be information acquired by the management unit 130 from the network 30 based on the location information 131 and stored.

[0042] The beacon generation unit 133 is a functional block that generates a Frame Body field of a beacon frame. The beacon generation unit 133 generates a Country IE of the beacon frame based on the location information 131. The beacon generation unit 133 generates a Power Constraint IE of the beacon frame based on the transmission power regulation information 132. The beacon generation unit 133 transmits the Frame Body field of the beacon frame including the Country IE and the Power Constraint IE to the MAC frame processing unit 120.

[0043] The PHY header processing unit 140 is a functional block that executes processing corresponding to the physical layer. When the base station 10 is a transmitting station, the PHY header processing unit 140 generates a wireless frame based on the MAC frame received from the MAC frame processing unit 120. When the base station 10 is a receiving station, the PHY header processing unit 140 extracts a MAC frame from the wireless frame received from the wireless signal processing unit 150 and transmits it to the MAC frame processing unit 120.

[0044] The radio signal processing unit 150 is a functional block that interfaces with the antenna. When the base station 10 is a transmitting station, the radio signal processing unit 150 converts the radio frame received from the PHY header processing unit 140 into a radio signal based on an MCS (Modulation and Coding Scheme) selected by the MCS control unit 160. The conversion process from the radio frame to the radio signal includes, for example, convolutional coding processing, interleaving processing, subcarrier modulation processing, inverse fast Fourier transform processing, OFDM (Orthogonal Frequency Division Multiplexing) modulation processing, and frequency conversion processing. When the base station 10 is a receiving station, the radio signal processing unit 150 converts the radio signal received from the antenna into a radio frame based on the MCS selected by the MCS control unit 160. The conversion process from the radio signal to the radio frame includes, for example, frequency conversion processing, OFDM demodulation processing, fast Fourier transform processing, subcarrier demodulation processing, deinterleaving processing, and Viterbi decoding processing.

[0045] The MCS control unit 160 is a functional block that selects an MCS to be used in conversion processing by the radio signal processing unit 150. The MCS control unit 160 selects an MCS based on reception power. Specific examples of the MCS include a modulation method, a coding rate, the number of subcarriers, a guard interval length, a number of MIMO (Multi-Input and Multi-Output) multiplexing, and a transmission power.

[0046] (Device Functionality Configuration) FIG. 7 is a block diagram illustrating an example of a functional configuration of a terminal according to the embodiment.

[0047] As shown in FIG. 7, the terminal 20 functions as a computer including a data processing unit 210, a MAC frame processing unit 220, a management unit 230, a PHY header processing unit 240, a radio signal processing unit 250, an MCS control unit 260, and an application execution unit 270.

[0048] The data processing unit 210 is a functional block that executes processes corresponding to the LLC layer and higher layers. When the terminal 20 is a transmitting station, the data processing unit 210 generates a Frame Body field of a data frame based on data received from the application execution unit 270, and transmits the data to the MAC frame processing unit 220. When the terminal 20 is a receiving station, the data processing unit 210 extracts data from the Frame Body field of the data frame received from the MAC frame processing unit 220, and transmits the data to the application execution unit 270.

[0049] The MAC frame processing unit 220 is a functional block that executes processing corresponding to the MAC layer. When the terminal 20 is a transmitting station, the MAC frame processing unit 220 generates a MAC frame based on the Frame Body field received from the data processing unit 210. When the terminal 20 is a receiving station, the MAC frame processing unit 220 extracts the Frame Body field from the MAC frame received from the PHY header processing unit 240. When the MAC frame is a data frame, the MAC frame processing unit 220 transmits the extracted Frame Body field to the data processing unit 210. When the MAC frame is a beacon frame, the MAC frame processing unit 220 transmits the extracted Frame Body field to the management unit 230.

[0050] The management unit 230 is a functional block that manages beacon frames. The management unit 230 includes a beacon processing unit 231 and a transmission power regulation determination unit 232. The management unit 230 stores determination result information 233.

[0051] The beacon processing unit 231 extracts a Country IE and a Power Constraint IE from the Frame Body field of the beacon frame received from the MAC frame processing unit 220. The beacon processing unit 231 transmits the extracted Country IE and Power Constraint IE to the transmission power regulation determination unit 232.

[0052] The transmission power restriction determination unit 232 acquires the restriction target of the transmission power in the area where the base station 10 is located from the network 30 via the base station 10 based on the Country IE received from the beacon processing unit 231. Specifically, the transmission power restriction determination unit 232 acquires information for identifying whether the total transmission power or the transmission power density is restricted. Based on the acquired information, the transmission power restriction determination unit 232 judges whether the restriction target of the maximum transmission power in the Country IE received from the beacon processing unit 231 is the total transmission power or the transmission power per unit frequency band. Depending on the result of the judgment, the transmission power restriction determination unit 232 calculates the upper limit value of the total transmission power when the restriction target is the total transmission power, and calculates the upper limit value of the transmission power per unit frequency band when the restriction target is the transmission power per unit frequency band. The transmission power restriction determination unit 232 stores the results of the judgment and calculation as the judgment result information 233.

[0053] The PHY header processing unit 240 is a functional block that executes processing corresponding to the physical layer. When the terminal 20 is a transmitting station, the PHY header processing unit 240 generates a wireless frame based on the MAC frame received from the MAC frame processing unit 220. When the terminal 20 is a receiving station, the PHY header processing unit 240 extracts a MAC frame from the wireless frame received from the wireless signal processing unit 250 and transmits it to the MAC frame processing unit 220.

[0054] The radio signal processing unit 250 is a functional block that interfaces with the antenna. When the terminal 20 is a transmitting station, the radio signal processing unit 250 converts the radio frame received from the PHY header processing unit 240 into a radio signal based on the MCS selected by the MCS control unit 260. When the terminal 20 is a receiving station, the radio signal processing unit 250 converts the radio signal received from the antenna into a radio frame based on the MCS selected by the MCS control unit 260. The conversion process is the same as the conversion process in the base station 10.

[0055] The MCS control unit 260 is a functional block that selects an MCS to be used in conversion processing by the radio signal processing unit 250. The MCS control unit 260 selects an MCS based on the received power and the determination result information 233. When selecting an MCS, the MCS control unit 260 also selects a frequency band.

[0056] The application execution unit 270 is a functional block that executes an application. The application execution unit 270 executes an application based on data received from the data processing unit 210. For example, the application execution unit 270 can display information about the application on the display 25. In addition, the application execution unit 270 can operate based on an operation of an input interface.

[0057] 1.2 Operation Next, the operation of the terminal according to the embodiment will be described.

[0058] 1.2.1 Transmission power regulation judgment operation The operation of determining whether or not a transmission power restriction is required in the terminal according to the embodiment will be described below. The operation of determining whether or not a transmission power restriction is required is included in the operation of receiving a radio signal from the base station 10 in the terminal 20.

[0059] FIG. 8 is a flowchart showing an example of a transmission power restriction determination operation in the terminal according to the embodiment.

[0060] When a wireless signal is received from the base station 10 (start), the wireless signal processor 250 converts the received wireless signal into a wireless frame. The PHY header processor 240 extracts a MAC frame from the wireless frame. The MAC frame processor 220 determines whether the extracted MAC frame is a beacon frame (S11).

[0061] If the MAC frame is a beacon frame (S11; yes), the beacon processing unit 231 extracts a Country IE and a Power Constraint IE from the Frame Body field of the beacon frame (S12).

[0062] The transmission power regulation determination unit 232 acquires information on whether the transmission power regulation target is the total transmission power or the transmission power density from the network 30 via the base station 10 based on the Country IE extracted in the process of S12 (S13).

[0063] The transmission power regulation determination unit 232 determines whether the transmission power density is the target of regulation of the transmission power acquired in the process of S13 (S14).

[0064] If the restriction target is the transmission power density (S14; yes), the transmission power restriction determination unit 232 determines that the restriction target of the maximum transmission power in the Country IE extracted in the process of S12 is the transmission power per unit frequency band. The transmission power restriction determination unit 232 calculates the upper limit of the transmission power per unit frequency band based on the Country IE and the Power Constraint IE (S15). The transmission power restriction determination unit 232 stores, as the determination result information 233, the fact that the restriction target is the transmission power per unit frequency band and the upper limit of the transmission power per unit frequency band.

[0065] If the restriction target is not the transmission power density (S14; no), the transmission power restriction determination unit 232 determines whether the restriction target of the transmission power acquired in the process of S13 is the total transmission power (S16).

[0066] If the restriction target is the total transmission power (S16; yes), the transmission power restriction determination unit 232 determines that the restriction target of the maximum transmission power in the Country IE extracted in the process of S12 is the total transmission power. The transmission power restriction determination unit 232 calculates the upper limit value of the total transmission power based on the Country IE and the Power Constraint IE (S17). The transmission power restriction determination unit 232 stores the fact that the restriction target is the total transmission power and the upper limit value of the total transmission power as the determination result information 233.

[0067] After processing S15 and after processing S17, if the restriction target is not the total transmission power (S16; no), and if the received wireless frame is not a beacon frame (S11; no), the transmission power restriction determination operation ends (END).

[0068] By operating as described above, the terminal 20 can recognize, based on the information notified by the base station 10, what restrictions are imposed on the transmission power.

[0069] 1.2.2 Frequency band control operation Next, a frequency band control operation in the terminal according to the embodiment will be described. The frequency band control operation is included in the MCS control operation of the terminal 20 in transmitting a radio signal to the base station 10.

[0070] Fig. 9 is a flowchart showing an example of a frequency band control operation in the terminal according to the embodiment. In the example of Fig. 9, it is assumed that a transmission power restriction determination operation is performed in advance, and thus determination result information 233 is stored.

[0071] When selecting an MCS (starting), the MCS control unit 260 determines whether or not to take transmission power regulation into consideration (S21). For example, when the received power at the base station 10 is below a threshold, the MCS control unit 260 determines to take transmission power regulation into consideration. When the received power at the base station 10 is not below the threshold, the MCS control unit 260 determines not to take transmission power regulation into consideration.

[0072] When the transmission power regulation is taken into consideration (S21; yes), MCS control section 260 determines whether the regulation target is the transmission power density or not based on determination result information 233 (S22).

[0073] If the restriction target is the transmission power density (S22; yes), the MCS control unit 260 determines to duplicate the radio frame (S23). Then, the MCS control unit 260 controls the MAC frame processing unit 220, the PHY header processing unit 240, and the radio signal processing unit 250 so as to transmit the radio frame to be duplicated and the duplicated radio frame in parallel on a plurality of channels. Such a transmission method is also called non-HT (High Throughput) duplicate transmission. Here, the radio frame to be duplicated may be a data frame, a management frame, or a control frame. The transmission power is controlled to be as high as possible within a range not exceeding the upper limit of the transmission power per unit frequency band. This allows the same data to be transmitted with a higher total transmission power than when the radio frame is not duplicated.

[0074] If the restriction target is not the transmission power density (S21; no), MCS control unit 260 determines whether the restriction target is the total transmission power or not based on determination result information 233 (S24).

[0075] If the restriction target is the total transmission power (S24; yes), the MCS control unit 260 determines to reduce the frequency band (S24). Specifically, for example, the MCS control unit 260 controls the MAC frame processing unit 220, the PHY header processing unit 240, and the radio signal processing unit 250 so as to transmit a radio signal with a reduced number of subcarriers compared to when the frequency band control operation is not performed. Specifically, for example, about 1 / 2 or 1 / 3 of the number of subcarriers used when the frequency band control operation is not performed are used. The transmission power is controlled to be as high as possible within a range that does not exceed the upper limit of the total transmission power. That is, the transmission power per unit frequency band is controlled to be higher than when the frequency band control operation is not performed. This allows the same data to be transmitted at a higher transmission power density than when the frequency band is not reduced.

[0076] After the process of S23, after the process of S25, or when the transmission power regulation is not taken into consideration (S21; no), the frequency band control operation ends (end).

[0077] 1.3 Effects of this embodiment According to the embodiment, the transmission power restriction determination unit 232 determines the restriction target of the transmission power based on the Country IE in the beacon frame. When it is determined that the restriction target is the transmission power density, the MCS control unit 260 determines to generate a second frame that is a copy of the first frame when transmitting the first frame. Based on the determination, the MAC frame processing unit 220, the PHY header processing unit 240, and the radio signal processing unit 250 transmit the first frame in the first frequency band (first channel) and further transmit the second frame in the second frequency band (second channel). This allows the terminal 20 to transmit multiple radio frames including the same data in parallel through multiple channels while complying with the restriction of the transmission power density. Therefore, the base station 10 can obtain the effect of frequency diversity when receiving a radio signal from the terminal 20, compared to a case where the base station 10 does not perform duplication of the radio frame. Therefore, even if the terminal 20 is located in an area far from the base station 10, a more stable radio communication environment can be provided.

[0078] Also, when it is determined that the restriction is imposed on the total transmission power, the MCS control unit 260 determines to reduce the frequency band used when transmitting the third frame from the third frequency band to the fourth frequency band. Specifically, the MCS control unit 260 determines to use the first subcarrier number, which is smaller than the second subcarrier number, in a certain channel. Based on the determination, the MAC frame processing unit 220, the PHY header processing unit 240, and the radio signal processing unit 250 transmit the third frame using the fourth frequency band (first subcarrier number). This allows the terminal 20 to increase the transmission power density of the radio frame compared to when the third frequency band is used while complying with the restriction on the total transmission power. Therefore, even when the terminal 20 is located in an area far from the base station 10, a more stable radio communication environment can be provided.

[0079] 2. Modifications The above-mentioned embodiment can be modified in various ways. For example, in the above-mentioned embodiment, the case where the beacon frame does not include information indicating what the regulated object is is described, but the present invention is not limited to this. The base station 10 may generate a beacon frame including information indicating what the regulated object is.

[0080] Fig. 10 is a diagram showing an example of a format of a beacon frame according to a modified example, and corresponds to Fig. 5 in the embodiment.

[0081] As shown in FIG. 10, the beacon frame may further include a transmission power restriction identifier in addition to the Country IE and the Power Constraint IE.

[0082] The transmission power regulation identifier is an information element that identifies, for example, whether the transmission power regulation target is the transmission power density or the total transmission power.

[0083] Thus, by receiving a beacon frame, the transmission power regulation determination unit 232 can determine whether the maximum transmission power in the Country IE is regulated on the transmission power per unit frequency band or on the total transmission power.

[0084] Fig. 11 is a flowchart showing an example of a transmission power restriction determination operation in a terminal according to a modified example, which corresponds to Fig. 8 in the embodiment.

[0085] When a wireless signal is received from the base station 10 (start), the wireless signal processor 250 converts the received wireless signal into a wireless frame. The PHY header processor 240 extracts a MAC frame from the wireless frame. The MAC frame processor 220 determines whether the extracted MAC frame is a beacon frame (S31).

[0086] If the MAC frame is a beacon frame (S31; yes), the beacon processing unit 231 extracts the transmission power regulation identifier, the Country IE, and the Power Constraint IE from the Frame Body field of the beacon frame (S32).

[0087] The transmission power regulation determination unit 232 determines whether the regulation target is the transmission power density based on the transmission power regulation identifier extracted in the process of S32 (S33).

[0088] If the restriction target is the transmission power density (S33; yes), the transmission power restriction determination unit 232 determines that the restriction target of the maximum transmission power in the Country IE extracted in the process of S32 is the transmission power per unit frequency band. The transmission power restriction determination unit 232 calculates the upper limit of the transmission power per unit frequency band based on the Country IE and the Power Constraint IE (S34).

[0089] If the restriction target is not the transmission power density (S33; no), the transmission power restriction determination unit 232 determines whether the restriction target is the total transmission power based on the transmission power restriction identifier extracted in the process of S32 (S35).

[0090] If the restriction target is the total transmission power (S35; yes), the transmission power restriction determination unit 232 determines that the restriction target of the maximum transmission power in the Country IE extracted in the process of S32 is the total transmission power. The transmission power restriction determination unit 232 calculates the upper limit of the total transmission power based on the Country IE and the Power Constraint IE (S36).

[0091] After the processing of S34 and after the processing of S36, if the restriction target is not the total transmission power (S35; no), and if the received wireless frame is not a beacon frame (S31; no), the transmission power restriction determination operation ends (END).

[0092] By operating as described above, the terminal 20 can recognize what restrictions are imposed on transmission power without accessing the network 30.

[0093] 3. Other Furthermore, each process according to the above-mentioned embodiment and modified examples can be stored as a program that can be executed by a processor, which is a computer. Alternatively, the program can be stored in a storage medium of an external storage device, such as a magnetic disk, an optical disk, or a semiconductor memory, and distributed. The processor can then read the program stored in the storage medium of the external storage device, and the processor's operation is controlled by the read program, thereby executing the above-mentioned process.

[0094] The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. [Explanation of symbols]

[0095] 1. Communication systems 10...Base station 20...Terminal 30…Network 11,21…CPU 12,22…ROM 13,23…RAM 14,24…Wireless communication module 15…Wired communication module 25…Display 26…Storage 110, 210...Data processing unit 120, 220...MAC frame processing section 130,230…Management Department 140, 240...PHY header processing section 150, 250...Radio signal processing unit 160,260…MCS control section 270…Application execution unit 131…location information 132...Transmission power regulation information 133...Beacon generation unit 231...Beacon processing unit 232...Transmission power regulation determination unit 233…Judgment result information A1,A2…area

Claims

1. a determination unit that determines whether a transmission power regulation is applicable based on a beacon frame; a transmitter that transmits a first frame in a first frequency band when it is determined that the regulated object is not a transmission power density, and that transmits the first frame in the first frequency band while further transmitting a second frame, which is a copy of the first frame, in a second frequency band when it is determined that the regulated object is a transmission power density; Equipped with Terminal.

2. the transmitter transmits the first frame and the second frame such that a first transmission power density in the first frequency band and a second transmission power density in the second frequency band are each equal to or lower than a first threshold. The terminal according to claim 1.

3. The transmission unit is If it is determined that the restriction target is not the total transmission power, a third frame is transmitted in a third frequency band; When it is determined that the restriction target is a total transmission power, the third frame is transmitted in a fourth frequency band which is narrower than the third frequency band. The terminal according to claim 1.

4. The fourth frequency band is included in the third frequency band. The terminal according to claim 3.

5. a number of first subcarriers in the fourth frequency band is less than a number of second subcarriers in the third frequency band; The terminal according to claim 3.

6. a transmission power density in the transmission of the third frame is higher when the fourth frequency band is used than when the third frequency band is used; The terminal according to claim 3.

7. A transmission method for a terminal, comprising: Determining whether or not a transmission power regulation is applicable based on the beacon frame; transmitting a first frame in a first frequency band when it is determined that the regulated object is not a transmission power density, and transmitting a second frame, which is a copy of the first frame, in a second frequency band while transmitting the first frame in the first frequency band when it is determined that the regulated object is a transmission power density; Equipped with The method of sending the device.

8. In the terminal, the computer Determine whether or not transmission power is subject to regulation based on the beacon frame; when it is determined that the regulated object is not transmission power density, a first frame is transmitted in a first frequency band, and when it is determined that the regulated object is transmission power density, while transmitting the first frame in the first frequency band, a second frame which is a copy of the first frame is further transmitted in a second frequency band. Sending program.

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