Base station device and communication method

Abstract

To reduce the number of base stations and access points.SOLUTION: A base station device having a plurality of antenna elements is a base station device having a plurality of antenna elements includes a signal processing unit that generates a plurality of transmission streams for transmission in the same time zone and the same frequency band, and weights the plurality of transmission streams, and a transmission portion that transmits a plurality of transmission signals obtained by weighting from the plurality of antenna elements to one or more terminals, and the number of transmission signals that can be transmitted simultaneously in the same time zone and the same frequency band is set to differ depending on the communication range of the base station device to which each of the one or more terminals belongs.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a communication device and a communication method. [Background technology]

[0002] In wireless communication, massive Multiple-Input Multiple-Output (MIMO) is a transmission method that uses a large number of antennas in order to increase the capacity of base stations, access points, and the like.

[0003] For example, Patent Document 1 and Non-Patent Document 1 disclose a method in which a base station and an access point generate multiple beams and simultaneously access multiple terminals, thereby improving capacity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2015-523757 [Non-patent literature]

[0005] [Non-Patent Document 1] EG Larsson, O. Edfors, F. Tufvesson, and TL Marzetta, "Massive MIMO for next generation wireless systems", IEEE Communication Magazine, vol.52, no.2, pp.186-195, February 2014, Summary of the Invention

[0006] However, radio waves with frequencies of, for example, 5 GHz or higher, more specifically, 5 GHz, 20 GHz, and 60 GHz bands, attenuate faster than microwave radio waves, resulting in a narrower communication distance. In order to reduce the power consumption of the entire communication system and reduce the costs of the entire system, there is a demand to "reduce the number of base stations and access points while ensuring a communication area." One method for achieving this is to increase the communication distance range of each base station and each access point.

[0007] However, in Patent Document 1 and Non-Patent Document 1, no consideration is given to expanding the communication range of base stations and access points when the massive MIMO system is applied.

[0008] Therefore, one aspect of the present disclosure provides a base station device having a plurality of antenna elements, the base station device comprising: a signal processing unit that generates a plurality of transmission streams for transmission in the same time period and the same frequency band and weights the plurality of transmission streams; and a transmission unit that transmits a plurality of transmission signals obtained by the weighting from the plurality of antenna elements to one or more terminals, wherein the number of transmission signals that can be simultaneously transmitted in the same time period and the same frequency band is set to differ depending on the communication range of the base station device to which each of the one or more terminals belongs.

[0009] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0010] According to one aspect of the present disclosure, when a massive MIMO system is applied, the communication range of base stations and access points can be expanded, thereby reducing the number of base stations and access points while ensuring a communication area. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram showing an example of a configuration of a base station according to an embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of a configuration of an antenna unit; [Diagram 3] FIG. 2 shows a configuration of a base station different from that of FIG. 1 according to an embodiment. [Figure 4] FIG. 1 shows an example of a terminal configuration. [Diagram 5] FIG. 1 is a diagram showing an example of a configuration of an antenna unit; [Figure 6] FIG. 5 shows a configuration of a terminal different from that of the terminal of FIG. 4 in the embodiment. [Figure 7] A diagram showing an example of a communication state when a base station is transmitting four transmission beams. [Figure 8] FIG. 8 is a diagram showing an example of the state of a modulated signal transmitted by a base station when the base station and a terminal are in the communication state shown in FIG. [Figure 9] A diagram showing an example of a communication state when a base station is transmitting two transmission beams. [Figure 10] FIG. 10 is a diagram showing an example of the state of a modulated signal transmitted by a base station when the base station and a terminal are in the communication state shown in FIG. [Figure 11] A diagram showing an example of communication between a base station and each terminal. [Figure 12] FIG. 1 shows an example of the state of a base station and a terminal. [Figure 13] FIG. 1 shows an example of the state of a base station and a terminal. [Figure 14] FIG. 1 is a diagram showing an example of the state of a modulated signal transmitted by a base station; [Figure 15] FIG. 1 is a diagram showing an example of a communication state between a base station and a terminal according to an embodiment of the present invention; [Figure 16] A diagram showing the "limits of communication" for a base station [Figure 17] FIG. 1 is a diagram showing a first example of a frame structure of one or more transmission beams (or modulated signals) transmitted by a base station. [Figure 18] FIG. 2 is a diagram showing a second example of a frame structure of one or more transmission beams (or modulated signals) transmitted by a base station. [Figure 19A]FIG. 1 shows an example of a transmission beam constituting each frame. [Figure 19B] A diagram showing an example of a stream that constitutes each frame. [Figure 20] FIG. 1 shows a first example of a subframe configuration in an i-th frame. [Figure 21] FIG. 1 is a diagram showing an example of a communication state between a base station and a terminal according to an embodiment of the present invention; [Figure 22] FIG. 11 is a diagram showing a second example of a subframe configuration in the i-th frame. [Figure 23] FIG. 11 is a diagram showing a third example of a subframe configuration in the i-th frame. [Figure 24] FIG. 11 is a diagram showing a fourth example of a subframe configuration in the i-th frame. [Diagram 25] FIG. 5 is a diagram showing a fifth example of a subframe configuration in the i-th frame. [Figure 26] A diagram showing an example of a frame structure of one or more streams (or modulated signals) transmitted by a base station. [Figure 27] FIG. 13 is a diagram showing an example of division in the time direction; [Figure 28] FIG. 1 is a diagram showing an example of division in the frequency direction; [Figure 29] FIG. 1 is a diagram showing an example of a basic configuration of a communication device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each embodiment described below is merely an example, and the present disclosure is not limited to these embodiments.

[0013] (Embodiment) Fig. 1 is a diagram showing an example of the configuration of a base station in this embodiment. Note that the base station shown in Fig. 1 may be an access point or the like.

[0014] 101_1 indicates information #1, 101_2 indicates information #2, ..., 101_M indicates information #M. In other words, 101_m indicates information #m (m is an integer between 1 and M. Note that M is an integer greater than or equal to 2). Note that it is not necessary for all information from #1 to #M to exist.

[0015] If the communication partners are terminal #1, terminal #2, ..., terminal #U (U is an integer less than or equal to M), then information #i will either "not exist" or "data to be transmitted to any of the terminals."

[0016] The signal processing unit 102 receives as input information #1 (101_1), information #2 (101_2), ..., information #M (101_M), and a control signal 159. The signal processing unit 102 performs signal processing based on information such as "information on an error correction coding method (e.g., coding rate or code length (block length))", "information on a modulation method", "information on precoding", and "transmission method (e.g., a multiplexing method)" included in the control signal 159, and outputs a signal after signal processing 103_1, a signal after signal processing 103_2, ..., and a signal after signal processing 103_M. That is, the signal processing unit 102 outputs a signal after signal processing 103_m. Note that it is not necessary for all of the signals after signal processing 103_1 to 103_M to exist.

[0017] At this time, the information #m (101_m) is subjected to error correction coding, and then mapping is performed using the set modulation method. This results in a baseband signal. Then, the baseband signals corresponding to each piece of information are collected and pre-coded. Alternatively, for example, OFDM (Orthogonal Frequency Division Multiplexing) may be applied.

[0018] The radio unit 104_1 receives the processed signal 103_1 and a control signal 159, performs processing such as band limitation, frequency conversion, and amplification based on the control signal 159, and outputs a modulated signal 105_1. The modulated signal 105_1 is then output as a radio wave from the antenna unit 106_1.

[0019] Similarly, radio unit 104_2 receives processed signal 103_2 and control signal 159, performs processes such as band limitation, frequency conversion, and amplification based on control signal 159, and outputs modulated signal 105_2. Then, modulated signal 105_2 is output as a radio wave from antenna unit 106_2.

[0020] Similarly, radio unit 104_M receives processed signal 103_M and control signal 159, performs processing such as band limiting, frequency conversion, and amplification based on control signal 159, and outputs modulated signal 105_M. Then, modulated signal 105_M is output as a radio wave from antenna unit 106_M.

[0021] If there is no signal after signal processing, each radio unit does not need to perform the above processing.

[0022] The radio unit group 153 receives the received signal group 152 received by the receiving antenna group 151 as input, performs processing such as frequency conversion, and outputs the baseband signal group 154. Note that the received signal group 152 includes one or more received signals, the receiving antenna group 151 includes one or more antennas, the radio unit group 153 includes one or more radio units, and the baseband signal group 154 ​​includes one or more received signals.

[0023] Signal processing unit 155 receives baseband signal group 154 ​​and performs demodulation and error correction decoding. Signal processing unit 155 also performs processes such as time synchronization, frequency synchronization, and channel estimation. At this time, signal processing unit 155 receives and processes modulated signals transmitted by one or more terminals, and thus obtains control information transmitted by each terminal along with data transmitted by each terminal. Therefore, signal processing unit 155 outputs data group 156 corresponding to one or more terminals and control information group 157 corresponding to one or more terminals. Data group 156 includes one or more pieces of data, and control information group 157 includes one or more pieces of control information.

[0024] The setting unit 158 ​​receives the control information group 157 as input, and determines, based on the control information group 157, the "error correction coding method (e.g., coding rate or code length (block length))", "modulation method", "precoding method", "transmission method", "antenna settings", and the like, and outputs a control signal 159 including this determined information.

[0025] Antenna units 106_1, 106_2, . . . , 106_M receive a control signal 159. The configuration of antenna units 106_1, 106_2, . . . , 106_M will be described with reference to FIG.

[0026] Fig. 2 is a diagram showing an example of the configuration of antenna unit 106_m. Antenna unit 106_m is assumed to have a plurality of antennas as shown in Fig. 2. Although four antennas are shown in Fig. 2, the number of antennas is not limited to four. Each of antenna units 106_1, 106_2, ..., 106_M may have a plurality of antennas. In addition, the number of antennas provided in each of antenna units 106_1, 106_2, ..., 106_M does not have to be the same.

[0027] Distribution section 202 receives transmission signal 201 (corresponding to modulated signal 105_m in FIG. 1) as input, distributes transmission signal 201, and outputs signals 203_1, 203_2, 203_3, and 203_4.

[0028] Multiplication unit 204_1 receives signal 203_1 and control signal 200 (corresponding to control signal 159 in FIG. 1) as input, multiplies signal 203_1 by coefficient W1 based on information on the multiplication coefficient included in control signal 200, and outputs multiplied signal 205_1. Coefficient W1 is defined as a complex number. Therefore, W1 can also be a real number. If signal 203_1 is v1(t), multiplied signal 205_1 can be expressed as W1×v1(t) (t is time). Multiplied signal 205_1 is output as a radio wave from antenna 206_1.

[0029] Similarly, multiplication unit 204_2 receives signal 203_2 and control signal 200 as input, multiplies signal 203_2 by coefficient W2 based on information on the multiplication coefficient included in control signal 200, and outputs multiplied signal 205_2. Note that coefficient W2 is defined as a complex number. Therefore, W2 can also be a real number. If signal 203_2 is v2(t), multiplied signal 205_2 can be expressed as W2×v2(t). Multiplied signal 205_2 is output as a radio wave from antenna 206_2.

[0030] Similarly, multiplication unit 204_3 receives signal 203_3 and control signal 200 as input, multiplies signal 203_3 by coefficient W3 based on information on the multiplication coefficient included in control signal 200, and outputs multiplied signal 205_3. Coefficient W3 is defined as a complex number. Therefore, W3 can also be a real number. If signal 203_3 is v3(t), multiplied signal 205_3 can be expressed as W3×v3(t). Multiplied signal 205_3 is output as a radio wave from antenna 206_3.

[0031] Similarly, multiplication unit 204_4 receives signal 203_4 and control signal 200 as input, multiplies signal 203_4 by coefficient W4 based on information on the multiplication coefficient included in control signal 200, and outputs multiplied signal 205_4. Note that coefficient W4 is defined as a complex number. Therefore, W4 can also be a real number. If signal 203_4 is v4(t), multiplied signal 205_4 can be expressed as W4×v4(t). Multiplied signal 205_4 is output as a radio wave from antenna 206_4.

[0032] The absolute value of W1, the absolute value of W2, the absolute value of W3, and the absolute value of W4 may be equal to each other.

[0033] The radio waves output from the antennas 206_1 to 206_4 become predetermined transmission beams.

[0034] In the configuration of the base station described with reference to Fig. 1 and Fig. 2, setting unit 158 ​​determines a frame configuration, which will be described later. Information on the determined frame configuration is included in an output control signal 159. Signal processing unit 102 allocates signals after signal processing to frames based on the information on the frame configuration included in control signal 159. Radio units 104_1 to 104_M and antenna units 106_1 to 106_M perform their respective processes based on the information on the frame configuration included in control signal 159, and perform transmission processing of signals in accordance with the frame configuration.

[0035] In this embodiment, the base station may have a different configuration from that described with reference to FIGS.

[0036] Fig. 3 is a diagram showing the configuration of a base station according to this embodiment, which is different from the configuration of the base station in Fig. 1. In Fig. 3, the same components as those in Fig. 1 are given the same reference numbers and descriptions thereof will be omitted.

[0037] The weighting synthesis unit 301 receives modulated signal 105_1, modulated signal 105_2, ..., modulated signal 105_M, and control signal 159 as input. Then, based on information on weighting synthesis included in the control signal 159, the weighting synthesis unit 301 performs weighting synthesis on modulated signal 105_1, modulated signal 105_2, ..., modulated signal 105_M, and outputs weighted synthesis signals 302_1, 302_2, ..., 302_K (K is an integer of 1 or more). Then, the weighted synthesis signal 302_1 is output as a radio wave from antenna 303_1. Similarly, the weighted synthesis signal 302_2 is output as a radio wave from antenna 303_2. Similarly, the weighted synthesis signal 302_K is output as a radio wave from antenna 303_K.

[0038] Modulation signal 105_m to x m (t), the weighted synthesis signal 302_k (k is an integer between 1 and K) is expressed as y k (t), weighting coefficient A km Then, y k (t) is expressed as the following equation (1) (t is time).

[0039]

number

[0040] In addition, in formula (1), A km is a value that can be defined as a complex number. Therefore, A km can also be a real number.

[0041] Next, the configuration of the terminal in this embodiment will be described.

[0042] 4 is a diagram showing an example of the configuration of a terminal. Antenna units 401_1, 401_2, . . . , 401_N receive a control signal 410 (N is an integer equal to or greater than 1) as an input.

[0043] The radio section 403_1 receives the received signal 402_1 received by the antenna section 401_1 and a control signal 410 as input, performs processing such as frequency conversion on the received signal 402_1 based on the control signal 410, and outputs a baseband signal 404_1.

[0044] Similarly, the radio section 403_2 receives the received signal 402_2 received by the antenna section 401_2 and a control signal 410 as input, performs processing such as frequency conversion on the received signal 402_2 based on the control signal 410, and outputs a baseband signal 404_2.

[0045] Similarly, the radio unit 403_N receives a received signal 402_N received by the antenna unit 401_N and a control signal 410 as input, and performs processing such as frequency conversion on the received signal 402_N based on the control signal 410, and outputs a baseband signal 404_N.

[0046] However, all of the radio units 403_1, 403_2, ..., 403_N do not necessarily have to operate. Therefore, all of the baseband signals 404_1, 404_2, ..., 404_N do not necessarily exist.

[0047] The signal processing unit 405 receives baseband signals 404_1, 404_2, . . . , 404_N and a control signal 410, performs demodulation and error correction decoding processing based on the control signal 410, and outputs data 406, transmission control information 407, and control information 408. The signal processing unit 405 also performs processing such as time synchronization, frequency synchronization, and channel estimation.

[0048] The setting section 409 receives the control information 408 as input, performs settings relating to the receiving method, and outputs a control signal 410 .

[0049] The signal processing unit 452 receives the information 451 and the transmission control information 407 as input, performs processing such as error correction coding and mapping according to a set modulation method, and outputs a group of baseband signals 453 .

[0050] The radio unit group 454 receives the baseband signal group 453 as input, performs processing such as band limiting, frequency conversion, and amplification, and outputs a transmission signal group 455. The transmission signal group 455 is output as radio waves from a transmission antenna group 456. Note that the radio unit group 454 includes one or more radio units, the baseband signal group 453 includes one or more baseband signals, the transmission signal group 455 includes one or more transmission signals, and the transmission antenna group 456 includes one or more antennas.

[0051] Next, the configuration of antenna units 401_1, 401_2, . . . , 401_N will be described with reference to FIG. 2 by taking antenna unit 401_n as an example (n is an integer not less than 1 and not more than N).

[0052] Fig. 5 is a diagram showing an example of the configuration of antenna unit 401_n. Antenna unit 401_i is assumed to have a plurality of antennas as shown in Fig. 5. Although four antennas are shown in Fig. 5, the number of antennas is not limited to four. Each of antenna units 401_1, 401_2, ..., 401_N may have a plurality of antennas. Also, the number of antennas provided in each of antenna units 401_1, 401_2, ..., 401_N does not have to be the same.

[0053] Multiplication unit 503_1 receives received signal 502_1 received by antenna 501_1 and control signal 500 (corresponding to control signal 410 in FIG. 4) as input, multiplies received signal 502_1 by coefficient D1 based on information on the multiplication coefficient included in control signal 500, and outputs multiplied signal 504_1. Note that coefficient D1 is defined as a complex number. Therefore, D1 can also be a real number. If received signal 502_1 is e1(t), multiplied signal 504_1 can be expressed as D1×e1(t) (t is time).

[0054] Similarly, multiplication unit 503_2 receives received signal 502_2 received by antenna 501_2 and control signal 500 as input, multiplies received signal 502_2 by coefficient D2 based on information on the multiplication coefficient included in control signal 500, and outputs multiplied signal 504_2. Note that coefficient D2 can be defined as a complex number. Therefore, D2 can also be a real number. If received signal 502_2 is e2(t), multiplied signal 504_2 can be expressed as D2×e2(t).

[0055] Similarly, multiplication unit 503_3 receives received signal 502_3 received by antenna 501_3 and control signal 500 as input, multiplies received signal 502_3 by coefficient D3 based on information on the multiplication coefficient included in control signal 500, and outputs multiplied signal 504_3. Note that coefficient D3 can be defined as a complex number. Therefore, D3 can also be a real number. If received signal 502_3 is e3(t), multiplied signal 504_3 can be expressed as D3×e3(t).

[0056] Similarly, multiplication unit 503_4 receives received signal 502_4 received by antenna 501_4 and control signal 500 as input, multiplies received signal 502_4 by coefficient D4 based on information on the multiplication coefficient included in control signal 500, and outputs multiplied signal 504_4. Note that coefficient D4 can be defined as a complex number. Therefore, D4 ​​can also be a real number. If received signal 502_4 is e4(t), multiplied signal 504_4 can be expressed as D4×e4(t).

[0057] The combiner 505 receives the multiplied signals 504_1, 504_2, 504_3, and 504_4, adds the multiplied signals 504_1, 504_2, 504_3, and 504_4, and outputs a combined signal 506 (corresponding to the received signal 402_i in FIG. 4). The combined signal 506 is expressed as D1×e1(t)+D2×e2(t)+D3×e3(t)+D4×e4(t).

[0058] In this embodiment, it is also possible to employ a terminal configuration different from the terminal configuration described with reference to FIGS.

[0059] Fig. 6 is a diagram showing the configuration of a terminal in this embodiment that is different from the configuration of the terminal in Fig. 4. In Fig. 6, the same components as those in Fig. 4 are given the same numbers, and descriptions thereof will be omitted below.

[0060] Multiplication unit 603_1 receives received signal 602_1 received by antenna 601_1 and control signal 410 as input, multiplies received signal 602_1 by coefficient G1 based on information on the multiplication coefficient included in control signal 410, and outputs multiplied signal 604_1. Note that coefficient G1 can be defined as a complex number. Therefore, G1 can also be a real number. If received signal 602_1 is c1(t), multiplied signal 604_1 can be expressed as G1×c1(t) (t is time).

[0061] Similarly, the multiplier 603_2 receives the received signal 602_2 received by the antenna 601_2 and the control signal 410 as input, multiplies the received signal 602_2 by a coefficient G2 based on the information of the multiplication coefficient included in the control signal 410, and outputs a multiplied signal 604_2. Note that the coefficient G2 can be defined as a complex number. Therefore, G2 can also be a real number. If the received signal 602_2 is c2(t), the multiplied signal 604_2 can be expressed as G2×c2(t).

[0062] Similarly, the multiplication unit 603_L receives the received signal 602_L received by the antenna 601_L and the control signal 410 as input, multiplies the received signal 602_L by a coefficient GL based on the information of the multiplication coefficient included in the control signal 410, and outputs a multiplied signal 604_L. Note that the coefficient GL can be defined as a complex number. Therefore, GL can also be a real number. If the received signal 602_L is cL(t), the multiplied signal 604_L can be expressed as GL×cL(t).

[0063] Similarly, multiplication unit 603_l (l is an integer between 1 and L, L is an integer greater than or equal to 2) receives received signal 602_l received by antenna 601_l and control signal 410 as input, multiplies received signal 602_l by coefficient Gl based on information on the multiplication coefficient included in control signal 410, and outputs multiplied signal 604_l. Note that coefficient Gl can be defined as a complex number. Therefore, Gl can also be a real number. If received signal 602_l is cl(t), multiplied signal 604_i can be expressed as Gl×cl(t).

[0064] The processing unit 605 receives the multiplied signal 604_1, the multiplied signal 604_2, ..., the multiplied signal 604_L, and the control signal 410 as input, performs signal processing based on the control signal 410, and outputs processed signals 606_1, 606_2, ..., 606_N (N is an integer greater than or equal to 2).

[0065] At this time, the multiplied signal 604_l is p l(t), and the processed signal 606_n is r n If (t), then r n (t) is expressed by the following formula (2). (n is an integer between 1 and N.)

[0066]

number

[0067] In addition, in formula (2), B nl is a value that can be defined by complex numbers. Therefore, B nl can also be a real number.

[0068] As described above, the base station and terminal in this embodiment each have multiple antennas or an antenna unit composed of multiple antennas, and can control directivity. The receiving device of the terminal may "not control directivity". In this case, the terminal does not need to have multiple antennas. In other words, the terminal has one antenna. When the terminal has one antenna, it is the base station that controls directivity.

[0069] Next, a communication state in this embodiment where the base station and the terminal each control the directivity of the antenna will be described.

[0070] Fig. 7 is a diagram showing an example of a communication state when a base station 700 transmits four transmission beams. In Fig. 7, 700 is a base station, 701 indicates terminal #1, 702 indicates terminal #2, 703 indicates terminal #3, and 704 indicates terminal #4. The base station 700 transmits a modulated signal addressed to terminal #1 (701), a modulated signal addressed to terminal #2 (702), a modulated signal addressed to terminal #3 (703), and a modulated signal addressed to terminal #4 (704) at the same time using the same frequency (band). Fig. 7 shows the state at that time.

[0071] The base station 700 directs antenna directivity such as transmission beam 711 to terminal #1 (701), directs antenna directivity such as transmission beam 712 to terminal #2 (702), directs antenna directivity such as transmission beam 713 to terminal #3 (703), and directs antenna directivity such as transmission beam 714 to terminal #4 (704). That is, the base station 700 directs four transmission beams to each of the four terminals. In this way, the modulated signal addressed to terminal #1 (701), the modulated signal addressed to terminal #2 (702), the modulated signal addressed to terminal #3 (703), and the modulated signal addressed to terminal #4 (704) are less likely to interfere with each other, and each of the terminals #1 to #4 can ensure high data reception quality. To achieve this, the base station 700 has a configuration such as that shown in FIG. 1 or FIG. 3, for example.

[0072] In FIG. 7, terminal #1 (701) points its antenna directivity at beam 721 toward base station 700, terminal #2 (702) points its antenna directivity at beam 722 toward base station 700, terminal #3 (703) points its antenna directivity at beam 723 toward base station 700, and terminal #4 points its antenna directivity at beam 724 toward base station 700, but this is not limited to the above.

[0073] 7 indicates the limit position where a terminal can communicate when base station 700 transmits four transmission beams (or modulated signals). If a terminal is present within ellipse 799, the terminal can communicate with base station 700.

[0074] In addition, in Fig. 7, the base station 700 is described as transmitting four transmission beams (or modulated signals), but the transmission beams (or modulated signals) may be modulated symbol sequences. In that case, in Fig. 7, the base station 700 transmits four modulated symbol sequences. The ellipse 799 indicates the limit position where communication is possible when the number of modulated symbol sequences that can be simultaneously transmitted in the same time zone and the same frequency band is four.

[0075] In the present embodiment, the communication limit position is described as being elliptical, but the communication limit position is not limited to being elliptical.

[0076] Fig. 8 is a diagram showing an example of the state of a modulated signal transmitted by the base station 700 when the base station 700 and the terminals are in the communication state shown in Fig. 7. In Fig. 8, the horizontal axis indicates time. Fig. 8(a) shows an example of a modulated signal frame addressed to terminal #1, Fig. 8(b) shows an example of a modulated signal frame addressed to terminal #2, Fig. 8(c) shows an example of a modulated signal frame addressed to terminal #3, and Fig. 8(d) shows an example of a modulated signal frame addressed to terminal #4.

[0077] As shown in Fig. 8, each of the symbol group 801 addressed to terminal #1, the symbol group 802 addressed to terminal #2, the symbol group 803 addressed to terminal #3, and the symbol group 804 addressed to terminal #4 exists at least in the section T1 on the time axis. As already explained, the symbol group 801 addressed to terminal #1, the symbol group 802 addressed to terminal #2, the symbol group 803 addressed to terminal #3, and the symbol group 804 addressed to terminal #4 are transmitted from the base station 700 using the same frequency (band). This type of transmission method is called a multi-user MIMO (MU-MIMO (Multi User Multiple-Input Multiple-Output) method.

[0078] As described above, ellipse 799 in Fig. 7 is the limit position at which communication is possible when base station 700 transmits four transmission beams (or modulated signals). Note that when the number of transmission beams (or modulated signals) transmitted by base station 700 varies, the limit position at which communication is possible also varies. This is because, as will be explained later, there is a limit on the average transmission power of the base station. Next, the limit position at which communication is possible when base station 700 transmits two transmission beams (or modulated signals) will be explained.

[0079] Fig. 9 is a diagram showing an example of a communication state when base station 700 transmits two transmission beams. In Fig. 9, base station 700 transmits a modulated signal addressed to terminal #11 (901) and a modulated signal addressed to terminal #12 (902) at the same time using the same frequency (band). Fig. 9 shows the state at that time.

[0080] The base station 700 directs an antenna directivity such as a transmission beam 911 to terminal #11 (901), and directs an antenna directivity such as a transmission beam 912 to terminal #12 (902). In this way, the modulated signal addressed to terminal #11 (901) and the modulated signal addressed to terminal #12 (902) interfere less with each other, and each of terminals #1 and #2 can ensure high data reception quality. To achieve this, the base station 700 has a configuration such as that shown in FIG. 1 or FIG. 3, for example.

[0081] In FIG. 9, terminal #11 (901) directs its antenna toward base station 700 with beam 921 as its directivity, and terminal #12 (902) directs its antenna toward base station 700 with beam 922 as its directivity, but this is not limited to this.

[0082] An ellipse 999 in Fig. 9 indicates the communication limit position of a terminal when base station 700 transmits two transmission beams (or modulated signals). If a terminal is present within ellipse 999, the terminal can communicate with base station 700. For comparison, Fig. 9 shows "an ellipse 799 indicating the communication limit position of a terminal when base station transmits four transmission beams (or modulated signals)" shown in Fig. 7.

[0083] A base station has a set upper limit on the total average transmission power, regardless of the number of transmission beams (or the number of modulated signals transmitted). For this reason, as the number of transmission beams transmitted by a base station increases, the terminal's communication limit position becomes closer to the base station. Therefore, as shown in FIG. 9, ellipse 799 indicating "the terminal's communication limit position when the base station transmits four transmission beams (or modulated signals)" is closer to base station 700 than ellipse 999 indicating "the terminal's communication limit position when the base station transmits two transmission beams (or modulated signals)."

[0084] Fig. 10 is a diagram showing an example of the state of a modulated signal transmitted by base station 700 in Fig. 9 when the base station and terminals are in the communication state shown in Fig. 9. Fig. 10(a) shows an example of a frame of a modulated signal addressed to terminal #11 in the horizontal axis time, and Fig. 10(b) shows an example of a frame of a modulated signal addressed to terminal #12 in the horizontal axis time.

[0085] 10, symbol group 1001 addressed to terminal #11 and symbol group 1002 addressed to terminal #12 exist at least in section T2 on the time axis. As already explained, symbol group 1001 addressed to terminal #12 and symbol group 1002 addressed to terminal #12 are transmitted from the base station using the same frequency (band).

[0086] Fig. 11 is a diagram showing an example of communication between a base station and each terminal. Fig. 11(a) shows an example of transmission symbols in the horizontal axis time of a transmission signal transmitted by a base station, and Fig. 11(b) shows an example of transmission symbols in the horizontal axis time of a transmission signal transmitted by a terminal.

[0087] For example, as shown in Fig. 11, first, the base station transmits a base station control information symbol 1101. This symbol includes, for example, a PSK (Phase Shift Keying) symbol whose mapping is known in the terminal.

[0088] The terminal receives base station control information symbol 1101 transmitted by the base station and estimates the propagation environment (channel state estimation). Then, the terminal transmits terminal control information symbol 1151 including information on the channel state (for example, CSI: Channel State Information). In addition, the terminal may transmit terminal data symbol 1152.

[0089] The base station receives terminal control information symbol 1151 and terminal data symbol 1152 transmitted by the terminal. Then, the base station obtains channel state information contained in terminal control information symbol 1151, and calculates a multiplication coefficient (for example, a multiplication coefficient used in multiplication units 204_1 to 204_4 in FIG. 2, or a weighting combination coefficient used in weighting combination unit 301 in FIG. 3) for generating a transmission signal to be transmitted to this terminal. Then, the base station transmits base station control information symbol 1102 and base station data symbol 1103. At this time, the base station generates a transmission beam using the calculated multiplication coefficient.

[0090] The base station generates a transmission beam addressed to each terminal by exchanging symbols with multiple terminals as shown in Fig. 11. As a result, the base station transmits a transmission beam as shown in Fig. 7 and Fig. 9, for example.

[0091] Even after this, when the base station transmits a transmission beam to each terminal, the base station will communicate with each terminal as shown in Fig. 11. However, Fig. 11 is merely an example, and the method of sharing the propagation environment state of the modulated signal transmitted by the base station to the terminal is not limited to the method shown in Fig. 11.

[0092] FIG. 12 is a diagram showing an example of the state of a base station and terminals. The same components as those in FIG. 7 and FIG. 9 are given the same numbers. As described in FIG. 7, the base station 700 is assumed to transmit a modulated signal addressed to terminal #1 (701), a modulated signal addressed to terminal #2 (702), a modulated signal addressed to terminal #3 (703), and a modulated signal addressed to terminal #4 (704) at the same time and using the same frequency (band). Therefore, the base station 700 directs an antenna directivity such as a transmission beam 711 to terminal #1 (701), an antenna directivity such as a transmission beam 712 to terminal #2 (702), an antenna directivity such as a transmission beam 713 to terminal #3 (703), and an antenna directivity such as a transmission beam 714 to terminal #4 (704). In other words, the base station 700 directs four transmission beams to each of the four terminals. In this case, the four terminals are located inside ellipse 799, which indicates the "limit positions at which the terminals can communicate when the base station transmits four transmission beams (or modulated signals)," so base station 700 can communicate with terminal #1 (701), terminal #2 (702), terminal #3 (703), and terminal #4 (704).

[0093] On the other hand, since terminal #11 (901) and terminal #12 (902) are located at least outside ellipse 799, which indicates the "limit position at which the terminals can communicate when the base station transmits four transmission beams (or modulated signals)," base station 700 is deemed not to be communicating with terminal #11 (901) and terminal #12 (902).

[0094] FIG. 13 is a diagram showing an example of the state of a base station and terminals. The same numbers are used for configurations similar to those in FIG. 7 and FIG. 9. As described in FIG. 7, a state is considered in which the base station 700 transmits modulated signals addressed to terminal #1 (701), terminal #2 (702), terminal #3 (703), and terminal #4 (704) at the same time and using the same frequency (band). Therefore, the base station 700 directs antenna directivity such as a transmission beam 711 to terminal #1 (701), directs antenna directivity such as a transmission beam 712 to terminal #2 (702), directs antenna directivity such as a transmission beam 713 to terminal #3 (703), and directs antenna directivity such as a transmission beam 714 to terminal #4 (704). In other words, the base station 700 directs four transmission beams to each of the four terminals. In this case, it is assumed that the base station 700 is communicating with terminal #1 (701), terminal #2 (702), terminal #3 (703), and terminal #4 (704). These four terminals are located inside an ellipse 799 that indicates the "limit position at which the terminals can communicate when the base station transmits four transmission beams (or modulated signals)," so the base station 700 can communicate with terminal #1 (701), terminal #2 (702), terminal #3 (703), and terminal #4 (704).

[0095] In this state, consider the case where base station 700 transmits a modulated signal addressed to terminal #1 (701), a modulated signal addressed to terminal #2 (702), a modulated signal addressed to terminal #3 (703), a modulated signal addressed to terminal #4 (704), a modulated signal addressed to terminal #11 (901), and a modulated signal addressed to terminal #12 (902) at the same time and using the same frequency (band).

[0096] Fig. 14 is a diagram showing an example of the state of a modulated signal transmitted by the base station 700. Fig. 14(a) shows an example of the frame structure of a modulated signal addressed to terminal #1 in horizontal axis time, Fig. 14(b) shows an example of the frame structure of a modulated signal addressed to terminal #2 in horizontal axis time, Fig. 14(c) shows an example of the frame structure of a modulated signal addressed to terminal #3 in horizontal axis time, Fig. 14(d) shows an example of the frame structure of a modulated signal addressed to terminal #4 in horizontal axis time, Fig. 14(e) shows an example of the frame structure of a modulated signal addressed to terminal #11 in horizontal axis time, and Fig. 14(f) shows an example of the frame structure of a modulated signal addressed to terminal #12 in horizontal axis time.

[0097] 14, it is assumed that symbol group 1401 addressed to terminal #1, symbol group 1402 addressed to terminal #2, symbol group 1403 addressed to terminal #3, symbol group 1404 addressed to terminal #4, symbol group 1405 addressed to terminal #11, and symbol group 1406 addressed to terminal #12 are present at least in section T3. Also, it is assumed that symbol group 1401 addressed to terminal #1, symbol group 1402 addressed to terminal #2, symbol group 1403 addressed to terminal #3, symbol group 1404 addressed to terminal #4, symbol group 1405 addressed to terminal #11, and symbol group 1406 addressed to terminal #12 are transmitted from the base station using the same frequency (band).

[0098] In FIG. 13, when the base station 700 transmits the modulated signal shown in FIG. 14, the base station 700 transmits six transmission beams. As explained before, the ellipse 799 in FIG. 13 indicates the "limit position of communication of a terminal when the base station transmits four transmission beams (or modulated signals)". When the base station 700 transmits the modulated signal shown in FIG. 14 and transmits six transmission beams, the limit position of communication of a terminal is closer to the base station 700 than the ellipse 799. Therefore, depending on the positions of the terminals #1 (701), #2 (702), #3 (703), #4 (704), #11 (901), and #12 (902), there is a possibility that some terminals may have difficulty in communicating with the base station 700.

[0099] For example, in the case of the situation shown in FIG. 12, a terminal that is farther away from base station 700 than ellipse 799, which indicates the "limit position at which the terminal can communicate when the base station transmits four transmission beams (or modulated signals)," will have difficulty communicating with base station 700 if the communication format shown in FIG. 7 is adopted.

[0100] Therefore, it is desirable to apply a base station transmission method that enables more flexible communication than the communication form shown in FIG. 7, and to widen the communication distance range.

[0101] Also, for example, consider a state as shown in Fig. 13, that is, a state in which the number of terminals within "the limit positions where terminals can communicate when a base station transmits a certain number of transmission beams (or modulated signals)" is greater than the number of transmission beams. In this state, if a modulated signal is set to be transmitted to all terminals using the same time and frequency, there may be cases where it is difficult to transmit a modulated signal to all terminals using the same time and frequency, because an upper limit is set on the average transmission power that the base station can transmit.

[0102] An effective transmission method for dealing with such problems will be described below.

[0103] Fig. 15 is a diagram showing an example of a communication state between a base station and a terminal according to this embodiment. In Fig. 15, the same elements as those in Fig. 7 and Fig. 9 are given the same reference numbers and their description will be omitted.

[0104] The base station 700 transmits a transmission beam 711 addressed to terminal #1 (701), a transmission beam 712 addressed to terminal #2 (702), a transmission beam 713 addressed to terminal #3 (703), and a transmission beam 714 addressed to terminal #4 (704) at the same time (time tt1) and using the same frequency (band). At this time, each terminal may perform directivity control to direct each beam (beams 721 to 724) toward the base station 700. In addition, the base station 700 transmits a transmission beam 1511 addressed to terminal #11 (901) and a transmission beam 1512 addressed to terminal #12 (902) at the same time (time tt2) and using the same frequency (band). At this time, the terminals #11 (901) and #12 (902) may perform directivity control to direct beams 1521 and 1522, respectively, toward the base station 700. It is assumed that time tt1 and time tt2 are different times.

[0105] A method different from the above will now be described.

[0106] The base station 700 transmits a transmission beam 711 addressed to terminal #1 (701), a transmission beam 712 addressed to terminal #2 (702), a transmission beam 713 addressed to terminal #3 (703), and a transmission beam 714 addressed to terminal #4 (704) at the same time using the same frequency (band) (frequency (band) ff1). At this time, each terminal may perform directivity control to direct each beam (beams 721 to 724) toward the base station 700. In addition, the base station 700 transmits a transmission beam 1511 addressed to terminal #11 (901) and a transmission beam 1512 addressed to terminal #12 (902) at the same time using the same frequency (band) (frequency (band) ff2). At that time, terminal #11 (901) and terminal #12 (902) may perform directivity control to direct beams 1521 and 1522, respectively, toward base station 700. Note that frequency (band) ff1 and frequency (band) ff2 are different frequencies (bands).

[0107] In this way, when the base station 700 transmits four transmission beams, it transmits a transmission beam addressed to terminal #1 (701), a transmission beam addressed to terminal #2 (702), a transmission beam addressed to terminal #3 (703), and a transmission beam addressed to terminal #4 (704). In this case, since terminal #1 (701), terminal #2 (702), terminal #3 (703), and terminal #4 (704) are inside the ellipse 799 indicating the "limit position where terminals can communicate when the base station transmits four transmission beams (or modulated signals)", the base station 700 can communicate with terminal #1 (701), terminal #2 (702), terminal #3 (703), and terminal #4 (704). Then, when the base station 700 transmits two transmission beams, it transmits a transmission beam addressed to terminal #11 (901) and a transmission beam addressed to terminal #12 (902). Furthermore, since terminal #11 (901) and terminal #12 (902) are located inside ellipse 999, which indicates the "limit position at which terminals can communicate when the base station transmits two transmission beams (or modulated signals)," base station 700 is able to communicate with terminal #11 (901) and terminal #12 (902).

[0108] Another example of FIG. 15 will be described.

[0109] Fig. 16 is a diagram showing the "limit positions where communication is possible" of a base station 1600. In Fig. 16, ellipses indicating a plurality of "limit positions where communication is possible" are shown for the arrangement of the base station 1600.

[0110] An ellipse 1651 indicates the "limit position within which a terminal can communicate when a base station transmits 16 transmission beams (or modulated signals)." Communication is possible inside the ellipse 1651 if certain conditions are met.

[0111] An ellipse 1652 indicates the "limit position within which a terminal can communicate when a base station transmits eight transmission beams (or modulated signals)." Communication is possible inside the ellipse 1652 if certain conditions are met.

[0112] An ellipse 1653 indicates the "limit position within which a terminal can communicate when a base station transmits four transmission beams (or modulated signals)." Communication is possible inside the ellipse 1653 if certain conditions are met.

[0113] An ellipse 1654 indicates the "limit position within which a terminal can communicate when a base station transmits two transmission beams (or modulated signals)." Communication is possible inside the ellipse 1654 if certain conditions are met.

[0114] An ellipse 1655 indicates the "limit position within which a terminal can communicate when a base station transmits one transmission beam (or modulated signal)." Communication is possible inside the ellipse 1655 if certain conditions are met.

[0115] Fig. 17 is a diagram showing a first example of "frame configuration of one or more transmission beams (or modulated signals)" transmitted by a base station. The example shown in Fig. 17 is an example in which five communication limit positions as shown in Fig. 16 are set.

[0116] In Fig. 17, the horizontal axis is time. 1701_1 is the first frame, 1701_2 is the second frame, 1701_3 is the third frame, 1701_4 is the fourth frame, and 1701_5 is the fifth frame. The first frame (1701_1), the second frame (1701_2), the third frame (1701_3), the fourth frame (1701_4), and the fifth frame (1701_5) are assumed to be time division multiplexed (TDM).

[0117] At this time, the first frame (1701_1) is a frame for the base station to transmit up to 16 transmission beams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1651 in FIG. 16.

[0118] The second frame (1701_2) is a frame for the base station to transmit up to eight transmission beams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1652 in FIG. 16.

[0119] The third frame (1701_3) is a frame for the base station to transmit up to four transmission beams (or modulated signals). This frame is used to realize a communicable area corresponding to the area inside the ellipse 1653 in FIG. 16.

[0120] The fourth frame (1701_4) is a frame for a base station to transmit up to two transmission beams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1654 in FIG. 16.

[0121] The fifth frame (1701_5) is a frame for the base station to transmit one transmission beam (or modulated signal). This frame is used to realize a communication area corresponding to the area inside the ellipse 1655 in FIG. 16.

[0122] The first frame (1701_1) exists in time interval t1, the second frame (1701_2) exists in time interval t2, the third frame (1701_3) exists in time interval t3, the fourth frame (1701_4) exists in time interval t4, and the fifth frame (1701_5) exists in time interval t5.

[0123] In this case, the time intervals t1, t2, t3, t4, and t5 may be fixed time intervals, or may be configurable each time. For example, each time interval may be set depending on the number of terminals with which the base station communicates, the location of the terminals, etc.

[0124] In Fig. 17, the first frame (1701_1), the second frame (1701_2), the third frame (1701_3), the fourth frame (1701_4), and the fifth frame (1701_5) are arranged consecutively. The order in which the first frame (1701_1), the second frame (1701_2), the third frame (1701_3), the fourth frame (1701_4), and the fifth frame (1701_5) are transmitted is not limited to that shown in Fig. 17, and the transmission order of the frames may be changed as appropriate.

[0125] 17, for example, a multi-carrier transmission method such as OFDM (Orthogonal Frequency Division Multiplexing) may be used. A single-carrier transmission method may also be used. Therefore, a plurality of symbols may exist on the frequency axis.

[0126] Fig. 18 is a diagram showing a second example of the "frame configuration of one or more transmission beams (or modulated signals)" transmitted by the base station. The example shown in Fig. 18 is an example in which five communication limit positions as shown in Fig. 16 are set.

[0127] 18, the horizontal axis is time, 1701_1 is the first frame, 1701_2 is the second frame, 1701_3 is the third frame, 1701_4 is the fourth frame, and 1701_5 is the fifth frame. It is assumed that the first frame (1701_1), the second frame (1701_2), the third frame (1701_3), the fourth frame (1701_4), and the fifth frame (1701_5) are time division multiplexed (TDM).

[0128] At this time, the first frame (1701_1) is a frame for the base station to transmit up to 16 transmission beams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1651 in FIG. 16.

[0129] The second frame (1701_2) is a frame for the base station to transmit up to eight transmission beams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1652 in FIG. 16.

[0130] The third frame (1701_3) is a frame for the base station to transmit up to four transmission beams (or modulated signals). This frame is used to realize a communicable area corresponding to the area inside the ellipse 1653 in FIG. 16.

[0131] The fourth frame (1701_4) is a frame for a base station to transmit up to two transmission beams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1654 in FIG. 16.

[0132] The fifth frame (1701_5) is a frame for the base station to transmit one transmission beam (or modulated signal). This frame is used to realize a communication area corresponding to the area inside the ellipse 1655 in FIG. 16.

[0133] The first frame (1701_1) exists in time interval t1, the second frame (1701_2) exists in time interval t2, the third frame (1701_3) exists in time interval t3, the fourth frame (1701_4) exists in time interval t4, and the fifth frame (1701_5) exists in time interval t5.

[0134] In this case, the time intervals t1, t2, t3, t4, and t5 may be fixed time intervals, or may be configurable each time. For example, each time interval may be set depending on the number of terminals with which the base station communicates, the location of the terminals, etc.

[0135] In Fig. 18, the first frame (1701_1), the second frame (1701_2), the third frame (1701_3), the fourth frame (1701_4), and the fifth frame (1701_5) are arranged discretely. The order in which the first frame (1701_1), the second frame (1701_2), the third frame (1701_3), the fourth frame (1701_4), and the fifth frame (1701_5) are transmitted is not limited to that shown in Fig. 18, and the transmission order of the frames may be changed as appropriate.

[0136] 18, for example, a multi-carrier transmission method such as OFDM may be used. A single-carrier transmission method may also be used. Therefore, multiple symbols may exist on the frequency axis.

[0137] In addition to the "frame" in Fig. 17 and Fig. 18, there may be symbols such as "control information symbols (symbols required to demodulate and decode data symbols)" and "pilot symbols, reference symbols, and preambles for estimating channel fluctuations, detecting signals, performing frequency synchronization, performing time synchronization, and estimating frequency offsets." Other symbols may also be included. Examples of information transmitted using control information symbols include "information on the modulation method used to generate data symbols, information on the block length (code length) and coding rate of error correction codes, bit length of data symbols, and information required for terminals to link with base stations."

[0138] By transmitting a transmission beam with a frame configuration like that shown in Figures 17 and 18, the base station transmits multiple transmission beams at the same frequency and at the same time, which improves data transmission efficiency. In addition, under the condition that "the upper limit of the total average transmission power of a base station is set to a certain value, regardless of the number of transmission beams (or the number of modulated signals transmitted)," the effect of being able to widen the communication limit distance between the base station and a terminal can be obtained.

[0139] It should be noted that the frame configurations of the base station shown in FIGS. 17 and 18 are merely examples.

[0140] For example, suppose there are λ or more frames (λ is an integer equal to or greater than 2), i is an integer between 1 and λ, and j is an integer between 1 and λ. The i-th frame is a frame in which the base station transmits up to hi transmission beams (or modulated signals), and the j-th frame is a frame in which the base station transmits up to hj transmission beams (or modulated signals). In this case, it is sufficient that there exist i and j such that i ≠ j and hi ≠ hj in the frame configuration.

[0141] Alternatively, there may be λ or more frames (λ is an integer equal to or greater than 2), i is an integer equal to or greater than 1 and equal to λ, and j is an integer equal to or greater than 1 and equal to λ. The i-th frame is defined as "a frame in which the base station transmits up to hi transmission beams (or modulated signals)," and the j-th frame is defined as "a frame in which the base station transmits up to hj transmission beams (or modulated signals)." In this case, the frame configuration may be such that "hi ≠ hj" holds for all i and all j such that i ≠ j.

[0142] Fig. 19A is a diagram showing an example of a transmission beam constituting each frame (a first frame 1701_1 to a fifth frame 1701_5). Fig. 19B is a diagram showing an example of a stream constituting each frame (a first frame 1701_1 to a fifth frame 1701_5).

[0143] Fig. 19A shows the configuration of the transmission beam of the i-th frame in Fig. 17 and Fig. 18, where the horizontal axis of Fig. 19A (1) is time, and 1901_1 shows the symbol group of transmission beam #1 of the i-th frame. The horizontal axis of Fig. 19A (2) is time, and 1901_2 shows the symbol group of transmission beam #2 of the i-th frame. Similarly, the horizontal axis of Fig. 19A (ui) is time, and 1901_ui shows the symbol group of transmission beam #ui of the i-th frame.

[0144] In the case of the first frame 1701 in FIG. 17 and FIG. 18, u1 is an integer between 0 and 16, and when u1 is 1 or more, a symbol group from transmission beam #1 to transmission beam #u1 exists. Note that when u1 is 0, no transmission beam exists. Similarly, in the case of the second frame 1702 in FIG. 17 and FIG. 18, u2 is an integer between 0 and 8, and when u2 is 1 or more, a symbol group from transmission beam #1 to transmission beam #u2 exists. Note that when u2 is 0, no transmission beam exists. In the case of the third frame 1703 in FIG. 17 and FIG. 18, u3 is an integer between 0 and 4, and when u3 is 1 or more, a symbol group from transmission beam #1 to transmission beam #u3 exists. Note that when u3 is 0, no transmission beam exists. In the case of the fourth frame 1704 in FIG. 17 and FIG. 18, u4 is an integer between 0 and 2, and when u4 is 1 or more, a symbol group from transmission beam #1 to transmission beam #u4 exists. Note that when u4 is 0, there is no transmission beam. In the case of the fifth frame 1705 in Figs. 17 and 18, u5 is an integer between 0 and 1, and when u5 is 1 or greater, there are symbol groups of transmission beam #1 to transmission beam #u5. When u5 is 0, there is no transmission beam.

[0145] In Figure 19A, symbol group 1901_1 of transmission beam #1 of the i-th frame, symbol group 1901_2 of transmission beam #2 of the i-th frame, ..., symbol group 1901_ui of transmission beam #ui of the i-th frame exist in time interval T4 and are symbol groups transmitted by the base station using the same frequency.

[0146] The frame in this embodiment may have subframes for allocating the symbol groups of each transmission beam (or modulated signal) described above. Also, the frame may not have subframes. Next, the configuration of the subframes in the frame will be described.

[0147] 20 is a diagram showing a first example of a subframe configuration in an i-th frame. The i-th frame shown in Fig. 20 is the i-th frame described using Figs. 17, 18, etc.

[0148] In FIG. 20, the horizontal axis represents time. The i-th frame is composed of subframe #1 (2001_1) of the i-th frame, subframe #2 (2001_2) of the i-th frame, ..., subframe #vi (2001_vi) of the i-th frame. In other words, the i-th frame is composed of vi subframes. FIG. 20 shows an example in which the subframes are time division multiplexed (TDM). Also, vi is an integer equal to or greater than 1. The value of vi is set individually for each value of i. The value of vi may change with time.

[0149] In this case, as already explained, the i-th frame is assumed to be "a frame in which a base station transmits up to hi transmission beams (or modulated signals)." In each subframe of the i-th frame in FIG. 20, the number of transmission beams (or modulated signals) can be set individually. However, the number of transmission beams (or modulated signals) in each subframe must satisfy the condition of a maximum of hi. Therefore, if the "number of transmission beams (or modulated signals)" of subframe #k (k is an integer between 1 and vi) of the i-th frame is bk (bk is an integer between 0 and vi), then bk is an integer between 0 and hi (or between 1 and vi).

[0150] As described above, it has been described that the i-th frame is composed of subframes. An example of a method for implementing this and its effects will be described with reference to FIG.

[0151] Fig. 21 is a diagram showing an example of communication states between a base station and terminals according to this embodiment. In Fig. 21, the same configurations as those in Fig. 7, Fig. 9, and Fig. 15 are given the same numbers, and their description will be omitted. In Fig. 21, the difference from Fig. 15 is that terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104) are present outside ellipse 799 indicating "the limit position where terminals can communicate when a base station transmits four transmission beams (or modulated signals)" and inside ellipse 999 indicating "the limit position where terminals can communicate when a base station transmits two transmission beams (or modulated signals)".

[0152] In the case of Figure 21, due to the relationship between the number of transmission beams (or modulated signals) and the communication limit position, it becomes difficult for base station 700 to communicate with terminal #11 (901), terminal #12 (902), terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104) using six transmission beams (or modulated signals), for example.

[0153] In other words, if the i-th frame is not divided into subframes, until terminal #11 (901) and terminal #12 (902) have completed communication with base station 700, it will be difficult for terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104) to communicate with base station 700.

[0154] On the other hand, when the i-th frame is divided by subframes, for example, when the i-th frame is divided into three subframes (called "subframe 1," "subframe 2," and "subframe 3"), base station 700 communicates with terminal #11 (901) using the first transmission beam in "subframe 1," communicates with terminal #12 (902) using the second transmission beam in "subframe 1," communicates with terminal #21 (2101) using the first transmission beam in "subframe 2," communicates with terminal #22 (2102) using the second transmission beam in "subframe 2," communicates with terminal #23 (2103) using the first transmission beam in "subframe 3," and communicates with terminal #24 (2104) using the second transmission beam in "subframe 3." This enables the base station 700 to communicate with terminal #11 (901), terminal #12 (902), terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104).

[0155] It should be noted that the method of allocating terminals to the transmission beams of each subframe of the i-th frame is not limited to the above description.

[0156] In a state such as that shown in FIG. 21, for example, a plurality of subframes and a plurality of transmission beams may be assigned to a "certain terminal" as described below.

[0157] For example, the base station 700 communicates with terminal #11 (901) using the first transmission beam in "subframe 1", communicates with terminal #12 (902) using the second transmission beam in "subframe 1", communicates with terminal #11 (901) using the first transmission beam in "subframe 2", communicates with terminal #22 (2102) using the second transmission beam in "subframe 2", communicates with terminal #23 (2103) using the first transmission beam in "subframe 3", communicates with terminal #24 (2104) using the second transmission beam in "subframe 3", and communicates with terminal #21 (2101) using the first transmission beam in "subframe 4". That is, in this case, multiple subframes are assigned to terminal #11 (901).

[0158] Also, for example, the base station 700 communicates with terminal #11 (901) using the first transmission beam in "subframe 1", communicates with terminal #12 (902) using the second transmission beam in "subframe 1", communicates with terminal #11 (901) using the first transmission beam in "subframe 2", communicates with terminal #22 (2102) using the second transmission beam in "subframe 2", communicates with terminal #23 (2103) using the first transmission beam in "subframe 3", communicates with terminal #24 (2104) using the second transmission beam in "subframe 3", communicates with terminal #21 (2101) using the first transmission beam in "subframe 4", and also communicates with terminal 21 (2101) using the second transmission beam in "subframe 4". That is, in this case, multiple subframes are assigned to terminal #11 (901), and multiple transmission beams are assigned to terminal #21 (2101).

[0159] Also, for example, base station 700 communicates with terminal #11 (901) using the first transmission beam in "subframe 1", communicates with terminal #12 (902) using the second transmission beam in "subframe 1", communicates with terminal #11 (901) using the first transmission beam in "subframe 2", communicates with terminal #22 (2102) using the second transmission beam in "subframe 2", communicates with terminal #23 (2103) using the first transmission beam in "subframe 3", communicates with terminal #24 (2104) using the second transmission beam in "subframe 3", communicates with terminal #21 (2101) using the first transmission beam in "subframe 4", communicates with terminal 21 (2101) using the second transmission beam in "subframe 4", and communicates with terminal (2101) using the first transmission beam in "subframe 5". That is, in this case, multiple subframes are assigned to terminal #11 (901), and multiple subframes and multiple transmission beams are assigned to terminal #21 (2101).

[0160] Fig. 22 is a diagram showing a second example of a subframe configuration in the i-th frame. The i-th frame shown in Fig. 22 is the i-th frame described using Figs. 17, 18, etc.

[0161] As an explanation of the premise, Fig. 19B will be described. Fig. 19B is a diagram showing an example of a stream constituting each frame (a first frame 1701_1 to a fifth frame 1701_5) in Figs. 17 and 18.

[0162] Fig. 19B shows the configuration of the stream of the i-th frame in Fig. 17 and Fig. 18, where the horizontal axis of (1) in Fig. 19B is time, and 1901B_1 shows the symbol group of stream #1 of the i-th frame. The horizontal axis of (2) in Fig. 19B is time, and 1901B_2 shows the symbol group of stream #2 of the i-th frame. Similarly, the horizontal axis of (i) in Fig. 19B is time, and 1901B_ui shows the symbol group of stream #ui of the i-th frame.

[0163] In the case of the first frame 1701 in FIG. 17 and FIG. 18, u1 is an integer between 0 and 16, and when u1 is 1 or more, a symbol group from stream #1 to stream #u1 exists. Note that when u1 is 0, no stream exists. Similarly, in the case of the second frame 1702 in FIG. 17 and FIG. 18, u2 is an integer between 0 and 8, and when u2 is 1 or more, a symbol group from stream #1 to stream #u2 exists. Note that when u2 is 0, no stream exists. In the case of the third frame 1703 in FIG. 17 and FIG. 18, u3 is an integer between 0 and 4, and when u3 is 1 or more, a symbol group from stream #1 to stream #u3 exists. Note that when u3 is 0, no stream exists. In the case of the fourth frame 1704 in FIG. 17 and FIG. 18, u4 is an integer between 0 and 2, and when u4 is 1 or more, a symbol group from stream #1 to stream #u4 exists. Note that when u4 is 0, no stream exists. 17 and 18, in the case of the fifth frame 1705, u5 is an integer between 0 and 1, and when u5 is 1 or greater, symbol groups from stream #1 to stream #u5 exist. Note that when u5 is 0, no stream exists.

[0164] In FIG. 19B, symbol group 1901B_1 of stream #1 of the i-th frame, symbol group 1901B_2 of stream #2 of the i-th frame, ..., symbol group 1901B_ui of stream #ui of the i-th frame exist in time interval T4 and are symbol groups transmitted by the base station using the same frequency.

[0165] In Fig. 22, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 22, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0166] As shown in FIG. 22, the i-th frame is composed of subframe #1 (2201_1) of the i-th frame, subframe #2 (2201_2) of the i-th frame, ..., subframe #vi (2201_vi) of the i-th frame. In other words, the i-th frame is composed of vi subframes. Note that FIG. 22 shows an example in which subframes are frequency division multiplexed (FDM: Frequency Division Multiplexing). Also, vi is an integer equal to or greater than 1. The value of vi is set individually for each value of i. The value of vi may change over time.

[0167] The method of using subframes can be considered in the same way as explained using Figures 20 and 21. In other words, a subframe is composed of one or more streams (or modulated signals), and terminals can be assigned for each subframe and stream. This makes it possible to obtain the same effects as explained using Figures 20 and 21.

[0168] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 22. Also, a transmission beam may be generated for each stream.

[0169] Fig. 23 is a diagram showing a third example of a subframe configuration in the i-th frame. The i-th frame shown in Fig. 23 is the i-th frame described using Figs. 17, 18, etc.

[0170] In Fig. 23, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 23, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0171] As shown in FIG. 23, the i-th frame is composed of subframe #1 (2301_1) of the i-th frame, subframe #2 (2301_2) of the i-th frame, subframe #3 (2301_3) of the i-th frame, subframe #4 (2301_4) of the i-th frame, subframe #5 (2301_5) of the i-th frame, subframe #6 (2301_6) of the i-th frame, ..., subframe #vi (2301_vi) of the i-th frame. That is, the i-th frame is composed of vi subframes. In the example of FIG. 23, subframe #1 of the i-th frame and subframe #2 of the i-th frame are time-division multiplexed, and further, the other subframes are division-multiplexed by a region composed of frequency and time. Also, vi is an integer of 1 or more. And, the value of vi is set individually for each value of i. The value of vi may be changed depending on time.

[0172] The method of using subframes is the same as that explained with reference to Fig. 22. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained with reference to Figs. 20 and 21.

[0173] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 23. Also, a transmission beam may be generated for each stream.

[0174] Fig. 24 is a diagram showing a fourth example of a subframe configuration in the i-th frame. The i-th frame shown in Fig. 24 is the i-th frame described using Figs. 17, 18, etc.

[0175] In Fig. 24, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 24, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0176] As shown in FIG. 24, the i-th frame is composed of subframe #1 (2401_1) of the i-th frame, subframe #2 (2401_2) of the i-th frame, subframe #3 (2401_3) of the i-th frame, subframe #4 (2401_4) of the i-th frame, subframe #5 (2401_5) of the i-th frame, ..., subframe #vi (2401_vi) of the i-th frame. That is, the i-th frame is composed of vi subframes. In the example of FIG. 24, subframe #2 of the i-th frame and subframe #vi of the i-th frame are frequency division multiplexed, and the other subframes are division multiplexed by regions composed of frequency and time. Also, vi is an integer of 1 or more. The value of vi is set individually for each value of i. The value of vi may be changed depending on time.

[0177] The method of using subframes is the same as that explained with reference to Fig. 22. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained with reference to Figs. 20 and 21.

[0178] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 22. Also, a transmission beam may be generated for each stream.

[0179] Fig. 25 is a diagram showing a fifth example of a subframe configuration in the i-th frame. The i-th frame shown in Fig. 25 is the i-th frame described using Figs. 17, 18, etc.

[0180] In Fig. 25, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 25, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0181] As shown in FIG. 25, the i-th frame is composed of subframe #1 (2501_1) of the i-th frame, subframe #2 (2501_2) of the i-th frame, subframe #3 (2501_3) of the i-th frame, subframe #4 (2501_4) of the i-th frame, subframe #5 (2501_5) of the i-th frame, ..., subframe #(vi-1) (2501_(vi-1)) of the i-th frame, and subframe #vi (2501_vi) of the i-th frame. That is, the i-th frame is composed of vi subframes. In the example of FIG. 25, the subframes are divided and multiplexed by regions composed of frequency and time. Also, vi is an integer equal to or greater than 1. And, the value of vi is set individually for each value of i. The value of vi may be changed depending on time.

[0182] The method of using subframes is the same as that explained with reference to Fig. 22. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained with reference to Figs. 20 and 21.

[0183] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 25. Also, a transmission beam may be generated for each stream.

[0184] In the above, the configuration of each frame in the time-divided frame has been described as shown in Figures 17 and 18. Next, a frequency-divided frame will be described.

[0185] Fig. 26 is a diagram showing an example of "frame configuration of one or more streams (or modulated signals)" transmitted by a base station. The example shown in Fig. 26 is an example in which five communication possible limit positions as shown in Fig. 16 are set.

[0186] In Fig. 26, the horizontal axis is time, and the vertical axis is frequency (carrier). 2601_1 is the first frame, 2601_2 is the second frame, 2601_3 is the third frame, 2601_4 is the fourth frame, and 2601_5 is the fifth frame. The first frame (2601_1), the second frame (2601_2), the third frame (2601_3), the fourth frame (2601_4), and the fifth frame (2601_5) are assumed to be frequency division multiplexed (FDM). Therefore, it is based on multicarrier transmission such as OFDM.

[0187] At this time, the first frame (2601_1) is a frame for the base station to transmit up to 16 streams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1651 in FIG. 16.

[0188] The second frame (2601_2) is a frame for a base station to transmit up to eight streams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1652 in FIG. 16.

[0189] The third frame (2601_3) is a frame for a base station to transmit up to four streams (or modulated signals). This frame is used to realize a communicable area corresponding to the area inside the ellipse 1653 in FIG. 16.

[0190] The fourth frame (2601_4) is a frame for a base station to transmit up to two streams (or modulated signals). This frame is used to realize a communication area corresponding to the area inside the ellipse 1654 in FIG. 16.

[0191] The fifth frame (2601_5) is a frame for a base station to transmit one stream (or modulated signal). This frame is used to realize a communication area corresponding to the area inside the ellipse 1655 in FIG. 16.

[0192] The first frame (2601_1) exists in frequency interval F1, the second frame (2601_2) exists in frequency interval F2, the third frame (2601_3) exists in frequency interval F3, the fourth frame (2601_4) exists in frequency interval F4, and the fifth frame (2601_5) exists in frequency interval F5.

[0193] In this case, the frequency intervals F1, F2, F3, F4, and F5 may be fixed frequency intervals, or may be set each time. For example, each frequency interval may be set depending on the number of terminals with which the base station communicates, the location of the terminals, etc.

[0194] It should be noted that the order of arrangement of the first frame (2601_1), the second frame (2601_2), the third frame (2601_3), the fourth frame (2601_4), and the fifth frame (2601_5) on the frequency axis is not limited to that shown in FIG. 26, and the arrangement positions of the frames may be changed as appropriate.

[0195] By transmitting a stream in a frame configuration as shown in Fig. 26, the base station transmits multiple transmission beams at the same frequency and at the same time, which improves data transmission efficiency. In addition, under the condition that "the upper limit of the total average transmission power of a base station is set to a certain value, regardless of the number of streams (or the number of modulated signals to be transmitted)," the effect of being able to widen the communication limit distance between the base station and the terminal can be obtained.

[0196] It should be noted that the frame configuration of the base station shown in FIG. 26 is merely an example.

[0197] For example, suppose there are λ or more frames (λ is an integer equal to or greater than 2), i is an integer equal to or greater than 1 and equal to λ, and j is an integer equal to or greater than 1 and equal to λ. If i ≠ j, then the i-th frame is "a frame in which the base station transmits up to hi streams (or modulated signals)," and the j-th frame is "a frame in which the base station transmits up to hj streams (or modulated signals)." In this case, it is sufficient that there exist i and j such that i ≠ j and hi ≠ hj in the frame configuration.

[0198] Alternatively, there may be λ or more frames (λ is an integer equal to or greater than 2), i is an integer equal to or greater than 1 and equal to λ, and j is an integer equal to or greater than 1 and equal to λ. The i-th frame is defined as "a frame in which the base station transmits up to hi streams (or modulated signals)," and the j-th frame is defined as "a frame in which the base station transmits up to hj streams (or modulated signals)." In this case, the frame configuration may be such that "hi ≠ hj" holds for all i and all j such that i ≠ j.

[0199] Next, an example of a stream in the frame shown in FIG. 26 will be described with reference to FIG. 19B.

[0200] Fig. 19B shows an example of a stream constituting each frame (first frame 2601_1 to fifth frame 2601_5) in Fig. 2. It is assumed that data can be transmitted for each stream. For example, if there is a first stream and a second stream, it is assumed that the first data can be transmitted in the first stream and the second data can be transmitted in the second stream.

[0201] Fig. 19B shows the configuration of the stream of the i-th frame in Fig. 26, where the horizontal axis of (1) in Fig. 19B is time, and 1901B_1 shows the symbol group of stream #1 of the i-th frame. The horizontal axis of (2) in Fig. 19B is time, and 1901B_2 shows the symbol group of stream #2 of the i-th frame. Similarly, the horizontal axis of (i) in Fig. 19B is time, and 1901B_ui shows the symbol group of stream #ui of the i-th frame.

[0202] In the case of the first frame 2601 of FIG. 26, u1 is an integer between 0 and 16, and when u1 is 1 or more, a symbol group from stream #1 to stream #u1 exists. Note that when u1 is 0, no stream exists. Similarly, in the case of the second frame 2602 of FIG. 26, u2 is an integer between 0 and 8, and when u2 is 1 or more, a symbol group from stream #1 to stream #u2 exists. Note that when u2 is 0, no stream exists. In the case of the third frame 2603 of FIG. 26, u3 is an integer between 0 and 4, and when u3 is 1 or more, a symbol group from stream #1 to stream #u3 exists. Note that when u3 is 0, no stream exists. In the case of the fourth frame 2604 of FIG. 26, u4 is an integer between 0 and 2, and when u4 is 1 or more, a symbol group from stream #1 to stream #u4 exists. Note that when u4 is 0, no stream exists. In the case of the fifth frame 2605 in Fig. 26, u5 is an integer between 0 and 1, and when u5 is greater than or equal to 1, symbol groups from stream #1 to stream #u5 exist. Note that when u5 is 0, no stream exists.

[0203] In FIG. 19B, symbol group 1901B_1 of stream #1 of the i-th frame, symbol group 1901B_2 of stream #2 of the i-th frame, ..., symbol group 1901B_ui of stream #ui of the i-th frame exist in time interval T4 and are symbol groups transmitted by the base station using the same frequency.

[0204] Next, the configuration of a subframe in the frame shown in Fig. 26 will be described with reference to Fig. 20. Fig. 20 shows an example of the configuration of a subframe in the i-th frame described with reference to Fig. 26 and so on.

[0205] In FIG. 20, the horizontal axis represents time. The i-th frame is composed of subframe #1 (2001_1) of the i-th frame, subframe #2 (2001_2) of the i-th frame, ..., subframe #vi (2001_vi) of the i-th frame. In other words, the i-th frame is composed of vi subframes. FIG. 20 shows an example in which subframes are time division multiplexed (TDM). Also, vi is an integer equal to or greater than 1. The value of vi is set individually for each value of i. The value of vi may also change with time.

[0206] In this case, as already explained, the i-th frame is assumed to be "a frame in which a base station transmits a maximum of hi streams (or modulated signals)." In each subframe of the i-th frame in FIG. 20, the number of streams (or modulated signals) can be set individually. However, the number of streams (or modulated signals) in each subframe must satisfy the condition of a maximum of hi. Therefore, if the "number of streams (or modulated signals)" of subframe #k (k is an integer between 1 and vi) of the i-th frame is bk (bk is an integer between 0 and vi), then bk is an integer between 0 and hi (or between 1 and vi).

[0207] As described above, it has been described that the i-th frame is composed of subframes. An example of a method for implementing this and its effects will be described with reference to FIG.

[0208] Fig. 21 shows an example of the communication state between the base station and terminals according to this embodiment. In Fig. 21, the same configurations as those in Fig. 7, Fig. 9, and Fig. 15 are given the same numbers, and their description will be omitted. In Fig. 21, the difference from Fig. 15 is that terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104) are present outside ellipse 799 indicating "the limit position where the terminal can communicate when the base station transmits four streams (or modulated signals)" and inside ellipse 999 indicating "the limit position where the terminal can communicate when the base station transmits two streams (or modulated signals)".

[0209] In the case of FIG. 21, due to the relationship between the number of streams (or modulated signals) and the communication limit position, it becomes difficult for base station 700 to communicate with terminal #11 (901), terminal #12 (902), terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104) using six streams (or modulated signals), for example.

[0210] In other words, if the i-th frame is not divided into subframes, until terminal #11 (901) and terminal #12 (902) have completed communication with base station 700, it will be difficult for terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104) to communicate with base station 700.

[0211] On the other hand, when the i-th frame is divided by subframes, for example, when the i-th frame is divided into three subframes (called "subframe 1", "subframe 2", and "subframe 3"), base station 700 communicates with terminal #11 (901) using the first stream of "subframe 1", communicates with terminal #12 (902) using the second stream of "subframe 1", communicates with terminal #21 (2101) using the first stream of "subframe 2", communicates with terminal #22 (2102) using the second stream of "subframe 2", communicates with terminal #23 (2103) using the first stream of "subframe 3", and communicates with terminal #24 (2104) using the second stream of "subframe 3". This enables the base station 700 to communicate with terminal #11 (901), terminal #12 (902), terminal #21 (2101), terminal #22 (2102), terminal #23 (2103), and terminal #24 (2104).

[0212] It should be noted that the method of reassigning terminals to the streams of each subframe of the i-th frame is not limited to the above description.

[0213] In the state shown in FIG. 21, for example, a plurality of subframes and a plurality of streams may be allocated to a "certain terminal" as described below.

[0214] For example, the base station 700 communicates with terminal #11 (901) using the first stream in "subframe 1", communicates with terminal #12 (902) using the second stream in "subframe 1", communicates with terminal #11 (901) using the first stream in "subframe 2", communicates with terminal #22 (2102) using the second stream in "subframe 2", communicates with terminal #23 (2103) using the first stream in "subframe 3", communicates with terminal #24 (2104) using the second stream in "subframe 3", and communicates with terminal #21 (2101) using the first stream in "subframe 4". That is, in this case, multiple subframes are assigned to terminal #11 (901).

[0215] Also, for example, the base station 700 communicates with terminal #11 (901) using the first stream of "subframe 1", communicates with terminal #12 (902) using the second stream of "subframe 1", communicates with terminal #11 (901) using the first stream of "subframe 2", communicates with terminal #22 (2102) using the second stream of "subframe 2", communicates with terminal #23 (2103) using the first stream of "subframe 3", communicates with terminal #24 (2104) using the second stream of "subframe 3", communicates with terminal #21 (2101) using the first stream of "subframe 4", and also communicates with terminal 21 (2101) using the second stream of "subframe 4". That is, in this case, multiple subframes are assigned to terminal #11 (901), and multiple streams are assigned to terminal #21 (2101).

[0216] Also, for example, the base station 700 communicates with terminal #11 (901) using the first stream of "subframe 1", communicates with terminal #12 (902) using the second stream of "subframe 1", communicates with terminal #11 (901) using the first stream of "subframe 2", communicates with terminal #22 (2102) using the second stream of "subframe 2", communicates with terminal #23 (2103) using the first stream of "subframe 3", communicates with terminal #24 (2104) using the second stream of "subframe 3", communicates with terminal #21 (2101) using the first stream of "subframe 4", communicates with terminal 21 (2101) using the second stream of "subframe 4", and communicates with terminal (2101) using the first stream of "subframe 5". That is, in this case, multiple subframes are assigned to terminal #11 (901), and multiple subframes and multiple streams are assigned to terminal #21 (2101).

[0217] Next, the configuration of subframes in the frame shown in Fig. 26 will be described with reference to Figs. 22 to 25. Fig. 22 shows an example of the configuration of the i-th frame different from that shown in Fig. 20, which has been described with reference to Fig. 26 etc.

[0218] In Fig. 22, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 22, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0219] As shown in FIG. 22, the i-th frame is composed of subframe #1 (2201_1) of the i-th frame, subframe #2 (2201_2) of the i-th frame, ..., subframe #vi (2201_vi) of the i-th frame. In other words, the i-th frame is composed of vi subframes. Note that FIG. 22 shows an example in which subframes are frequency division multiplexed (FDM: Frequency Division Multiplexing). Also, vi is an integer equal to or greater than 1. The value of vi is set individually for each value of i. The value of vi may change over time.

[0220] The method of using subframes is the same as that explained using Figures 20 and 21. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained using Figures 20 and 21.

[0221] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 22. Also, a transmission beam may be generated for each stream.

[0222] FIG. 23 shows an example of the configuration of the i-th frame that is different from those shown in FIGS. 20 and 22 and that has been described using FIG. 26 and other figures.

[0223] In Fig. 23, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 23, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0224] As shown in FIG. 23, the i-th frame is composed of subframe #1 (2301_1) of the i-th frame, subframe #2 (2301_2) of the i-th frame, subframe #3 (2301_3) of the i-th frame, subframe #4 (2301_4) of the i-th frame, subframe #5 (2301_5) of the i-th frame, subframe #6 (2301_6) of the i-th frame, ..., subframe #vi (2301_vi) of the i-th frame. That is, the i-th frame is composed of vi subframes. In the example of FIG. 23, subframe #1 of the i-th frame and subframe #2 of the i-th frame are time-division multiplexed, and further, the other subframes are division-multiplexed by a region composed of frequency and time. Also, vi is an integer of 1 or more. And, the value of vi is set individually for each value of i. The value of vi may be changed depending on time.

[0225] The method of using subframes is the same as that explained with reference to Fig. 22. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained with reference to Figs. 20 and 21.

[0226] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 23. Also, a transmission beam may be generated for each stream.

[0227] FIG. 24 shows an example of the configuration of the i-th frame that is different from those shown in FIGS. 20, 22, and 23 and that have been described using FIG. 26 and other figures.

[0228] In Fig. 24, the horizontal axis is time and the vertical axis is frequency (carrier or subcarrier). In Fig. 24, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0229] As shown in FIG. 24, the i-th frame is composed of subframe #1 (2401_1) of the i-th frame, subframe #2 (2401_2) of the i-th frame, subframe #3 (2401_3) of the i-th frame, subframe #4 (2401_4) of the i-th frame, subframe #5 (2401_5) of the i-th frame, ..., subframe #vi (2401_vi) of the i-th frame. That is, the i-th frame is composed of vi subframes. In the example of FIG. 24, subframe #2 of the i-th frame and subframe #vi of the i-th frame are frequency division multiplexed, and the other subframes are division multiplexed by regions composed of frequency and time. Also, vi is an integer of 1 or more. The value of vi is set individually for each value of i. The value of vi may be changed depending on time.

[0230] The method of using subframes is the same as that explained with reference to Fig. 22. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained with reference to Figs. 20 and 21.

[0231] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 22. Also, a transmission beam may be generated for each stream.

[0232] FIG. 25 shows an example of the configuration of the i-th frame that is different from those shown in FIGS. 20, 22, 23, and 24 and that have been described using FIG. 26 and other figures.

[0233] In FIG. 25, the horizontal axis is time and the vertical axis is frequency ((sub)carrier). For example, it is assumed that multicarrier transmission such as OFDM is used, and symbols exist in the frequency direction.

[0234] As shown in FIG. 25, the i-th frame is composed of subframe #1 (2501_1) of the i-th frame, subframe #2 (2501_2) of the i-th frame, subframe #3 (2501_3) of the i-th frame, subframe #4 (2501_4) of the i-th frame, subframe #5 (2501_5) of the i-th frame, ..., subframe #(vi-1) (2501_(vi-1)) of the i-th frame, and subframe #vi (2501_vi) of the i-th frame. That is, the i-th frame is composed of vi subframes. In the example of FIG. 25, the subframes are divided and multiplexed by regions composed of frequency and time. Also, vi is an integer equal to or greater than 1. And, the value of vi is set individually for each value of i. The value of vi may be changed with time.

[0235] The method of using subframes is the same as that explained with reference to Fig. 22. That is, a subframe is composed of one or more streams (or modulated signals), and terminals may be assigned for each subframe and stream. This makes it possible to obtain the same effects as those explained with reference to Figs. 20 and 21.

[0236] In this case, different beamforming may be performed for each subframe. That is, a transmission beam may be generated for each subframe in Fig. 25. Also, a transmission beam may be generated for each stream.

[0237] As described above, by determining the number of transmission beams (number of streams) for each frame and having the base station transmit multiple frames, the communication range differs for each frame, which has the effect of expanding the communication distance between the base station and the terminal.

[0238] The frame configuration, transmission beam configuration, stream configuration, subframe configuration, symbol group configuration, and the like described in this embodiment are merely examples, and these configurations are not limited to the configurations described in this embodiment. For example, the frame configuration, transmission beam configuration, stream configuration, subframe configuration, symbol group configuration, and the like described in this embodiment include data symbols, control information symbols including control information required for demodulating and decoding the data symbols, and symbols such as pilot symbols, reference symbols, and preambles used for estimating fluctuations in the propagation path, signal detection, frequency synchronization, time synchronization, and estimating a frequency offset. Alternatively, other symbols may be included. Examples of information transmitted using the control information symbols include information on the modulation method used to generate the data symbols, the block length (code length) of the error correction code, information on the coding rate, the bit length of the data symbols, and information required for the terminal to link with the base station.

[0239] Incidentally, time division (or time division multiplexing), frequency division (or frequency division multiplexing), and time and frequency domain division (or time and frequency domain division multiplexing) have been described for the frames in Figures 17 and 26, and the subframes in Figures 20, 22, 23, 24, 25, and 26. Next, another example of the configuration of the time boundary or frequency boundary of a frame or subframe will be described.

[0240] For example, when dividing in the time direction, consider a state as shown in Fig. 27. Fig. 27 is a diagram showing an example of division in the time direction.

[0241] In Fig. 27, the horizontal axis is time and the vertical axis is frequency (carrier). Fig. 27 shows an example in which the first region, the second region, the third region, and the fourth region are divided in the time direction.

[0242] As shown in FIG. 27, at time t1, a first region and a second region exist. At times t2 and t3, a second region and a third region exist. The third region and the fourth region do not overlap in the time direction. These cases are included in the definition of "division in the time direction." For example, a frame may be divided in time such that multiple frames exist at a certain time as shown in FIG. 27. Alternatively, a subframe may be divided in time such that multiple subframes exist at a certain time as shown in FIG. 27.

[0243] Moreover, as shown in the first to third regions in Fig. 27, one region may have different time widths at different frequencies. In other words, one region does not have to be rectangular in the time-frequency plane. These cases are included in the definition of "division in the time direction."

[0244] For example, when dividing in the frequency direction, consider a state as shown in Fig. 28. Fig. 28 is a diagram showing an example of division in the frequency direction.

[0245] In Fig. 28, the horizontal axis is frequency (carrier) and the vertical axis is time. Fig. 28 shows an example in which the first region, the second region, the third region, and the fourth region are divided in the frequency direction.

[0246] As shown in FIG. 28, carrier c1 has a first region and a second region. Carrier c2 and carrier c3 have a second region and a third region. The third region and the fourth region do not overlap in the frequency direction. These cases are included in the definition of "division in the frequency direction." For example, a frame may be divided in frequency such that there are multiple frames at a certain frequency (carrier) as shown in FIG. 28. Alternatively, a subframe may be divided in frequency such that there are multiple subframes at a certain frequency (carrier) as shown in FIG. 28.

[0247] Moreover, as shown in the first to third regions in Fig. 28, one region may have different frequency widths at different times. In other words, one region does not have to be rectangular in the time-frequency plane. These cases are included in the definition of "division in the frequency direction."

[0248] Furthermore, when dividing a frame and / or a subframe into time and frequency domains (or dividing and multiplexing the time and frequency domains), the division in the time direction may be performed as shown in Fig. 27, and the division in the frequency direction may be performed as shown in Fig. 28. That is, one region in a time-frequency plane such as a frame or a subframe may have different frequency widths at different times and different time widths at different frequencies.

[0249] In the above description, for example, Fig. 19A shows a transmission beam of a frame, and Fig. 19B shows a stream of the frame. The transmission beam and the stream both correspond to a modulation symbol sequence transmitted to a terminal.

[0250] An example of a basic configuration of a communication device such as a base station or an access point described above in detail will be described with reference to FIG. 29. The communication device 2900 in this embodiment includes a signal processor 2901 (e.g., corresponding to the signal processor 102 in FIG. 1 and FIG. 3) that adjusts the transmission timing and / or frequency of a modulation symbol sequence so that the modulation symbol sequence addressed to each terminal is transmitted in a frame corresponding to the communication range to which each terminal belongs among a plurality of frames defined by time and frequency band, and a weighting synthesis unit 2902 (e.g., corresponding to the multipliers 204_1 to 204_4 in FIG. 2 or the weighting synthesis unit 301 in FIG. 3) that weights each modulation symbol sequence and transmits it from each antenna element. The frames are set so that the number of modulation symbol sequences that can be simultaneously transmitted in the same time zone and the same frequency band differs depending on the communication range. The frame also includes a plurality of subframes defined by time division and / or frequency division of the frame. The signal processing unit 2901 assigns, to each of a plurality of subframes in a frame, modulation symbol sequences equal to or less than the number of modulation symbol sequences that can be simultaneously communicated, which is set for that frame.

[0251] In the above explanation, it was stated that "the upper limit of the total average transmission power is set to a certain value regardless of the number of transmission beams (or the number of modulated signals to be transmitted or the number of streams to be transmitted)," but the following provides further explanation on this point.

[0252] For example, it is assumed that a transmitting device such as a base station or a terminal has a total of four transmitting antennas: transmitting antenna #A, transmitting antenna #B, transmitting antenna #C, and transmitting antenna #D.

[0253] For example, in the first case, modulated signal A is transmitted from transmitting antenna #A with an average transmission power of 1 watt, modulated signal B is transmitted from transmitting antenna #B with an average transmission power of 1 watt, modulated signal C is transmitted from transmitting antenna #C with an average transmission power of 1 watt, and modulated signal D is transmitted from transmitting antenna #D with an average transmission power of 1 watt. In this first case, the total average transmission power is 4 watts.

[0254] In the second case, modulated signal A is transmitted from transmitting antenna #A with an average transmission power of a watts, modulated signal B is transmitted from transmitting antenna #B with an average transmission power of b watts, modulated signal C is transmitted from transmitting antenna #C with an average transmission power of c watts, and modulated signal D is transmitted from transmitting antenna #D with an average transmission power of d watts, where a, b, c, and d are real numbers greater than or equal to 0.

[0255] If the upper limit of the sum of the average transmission power in the second case and the first case is the same, that is, if the upper limit of the sum of the average transmission power in the second case is 4 watts, then a+b+c+d=4 watts. ≦ It may be 4. Although the first and second cases are described with respect to the case where four modulated signals are present, the above-mentioned rule (the rule that the upper limit of the sum of average transmission powers is set to a certain value) holds regardless of the number of modulated signals.

[0256] In addition, in the first and second cases, the case where a modulated signal is transmitted has been described, but the same rules also hold when a transmission beam (or stream) is transmitted instead of a modulated signal.

[0257] Specifically, for example, in a third case, transmit beam (or stream) E is transmitted with an average transmission power of 1 watt, transmit beam (or stream) F is transmitted with an average transmission power of 1 watt, transmit beam (or stream) G is transmitted with an average transmission power of 1 watt, and transmit beam (or stream) H is transmitted with an average transmission power of 1 watt. In this third case, the total average transmission power is 4W.

[0258] In the fourth case, transmit beam (or stream) E is transmitted with an average transmit power of e watts, transmit beam (or stream) F is transmitted with an average transmit power of f watts, transmit beam (or stream) G is transmitted with an average transmit power of g watts, and transmit beam (or stream) H is transmitted with an average transmit power of h watts. Note that e, f, g, and h are real numbers greater than or equal to 0.

[0259] If the upper limit of the sum of the average transmission power in the third and fourth cases is the same, that is, if the upper limit of the sum of the average transmission power in the fourth case is 4 watts, then e+f+g+h=4 watts. ≦ It should be noted that the third and fourth cases are described with respect to the case where there are four transmission beams (or streams), but the above-mentioned rule (the rule that the upper limit of the sum of the average transmission powers is set to a certain value) holds regardless of the number of transmission beams.

[0260] Furthermore, although the terms "frame" and "subframe" are used in this specification, these are not limited to these terms, and the essence of this disclosure would not change if other terms such as "slot," "subslot," "stream," "substream," "segment," and "subsegment" were used.

[0261] Of course, the embodiments and other contents described in this specification may be combined in combination.

[0262] Furthermore, each embodiment and other contents are merely examples. For example, even if a "modulation method, error correction coding method (error correction code to be used, code length, coding rate, etc.), control information, etc." is given as an example, it is possible to implement the same configuration even if a different "modulation method, error correction coding method (error correction code to be used, code length, coding rate, etc.), control information, etc." is applied.

[0263] Regarding the modulation method, even if a modulation method other than the modulation methods described in this specification is used, it is possible to implement the embodiments and other contents described in this specification. For example, APSK (Amplitude Phase Shift Keying) (e.g., 16APSK, 64APSK, 128APSK, 256APSK, 1024APSK, 4096APSK, etc.), PAM (Pulse Amplitude Modulation) (e.g., 4PAM, 8PAM, 16PAM, 64PAM, 128PAM, 256PAM, 1024PAM, 4096PAM, etc.), PSK (Phase Shift Keying) (e.g., BPSK, QPSK, 8PSK, 16PSK, 64PSK, 128PSK, 256PSK, 1024PSK, 4096PSK, etc.), QAM (Quadrature Amplitude Modulation) (e.g., 4QAM, 8QAM, 16QAM, 64QAM, 128QAM, 256QAM, 1024QAM, 4096QAM, etc.) may be applied, and uniform mapping or non-uniform mapping may be used in each modulation scheme. Also, the method of arranging 2, 4, 8, 16, 64, 128, 256, 1024, etc. signal points in the IQ plane (modulation schemes having 2, 4, 8, 16, 64, 128, 256, 1024, etc. signal points) is not limited to the signal point arrangement method of the modulation scheme shown in this specification.

[0264] In this specification, the transmitting device may be, for example, a communication / broadcasting device such as a broadcasting station, a base station, an access point, a terminal, a mobile phone, etc., and the receiving device may be, for example, a communication device such as a television, a radio, a terminal, a personal computer, a mobile phone, an access point, a base station, etc. In addition, the communication device in this disclosure may be a device having a communication function, and may be in a form that can be connected to a device for executing an application such as a television, a radio, a personal computer, a mobile phone, etc. through some interface. In addition, in this embodiment, symbols other than data symbols, for example, pilot symbols (preambles, unique words, postambles, reference symbols, etc.), symbols for control information, etc. may be arranged in any way in the frame. Here, they are named pilot symbols and symbols for control information, but any naming method may be used, and the function itself is important.

[0265] The pilot symbol may be, for example, a known symbol modulated by the transmitter / receiver using PSK modulation (or the receiver may be able to know the symbol transmitted by the transmitter by synchronizing), and the receiver uses this symbol to perform frequency synchronization, time synchronization, channel estimation (for each modulated signal) (CSI (Channel State Information) estimation), signal detection, etc.

[0266] In addition, the control information symbols are symbols used to transmit information that needs to be transmitted to the communication partner in order to realize communication other than data (such as applications) (for example, the modulation method, error correction coding method, coding rate of the error correction coding method used in the communication, configuration information in higher layers, etc.).

[0267] In addition, the present disclosure is not limited to each embodiment, and can be implemented with various modifications. For example, in each embodiment, the case where the communication is performed as a communication device is described, but the present disclosure is not limited to this, and the communication method can also be implemented as software.

[0268] For example, a program for executing the above-described communication method may be stored in advance in a ROM (Read Only Memory), and the program may be run by a CPU (Central Processing Unit).

[0269] In addition, a program for executing the above-mentioned communication method may be stored in a computer-readable storage medium, and the program stored in the storage medium may be recorded in the computer's RAM (Random Access Memory), causing the computer to operate according to the program.

[0270] Each of the configurations of the above-mentioned embodiments may be realized as an LSI (Large Scale Integration), which is typically an integrated circuit. These may be individually integrated into one chip, or may be integrated into one chip to include all or part of the configurations of each embodiment. Here, LSI is used, but depending on the degree of integration, it may be called an IC (Integrated Circuit), system LSI, super LSI, or ultra LSI. In addition, the method of integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. After LSI manufacture, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI may be used. Furthermore, if an integrated circuit technology that replaces LSI appears due to the progress of semiconductor technology or a different technology derived from it, naturally the technology may be used to integrate the functional blocks. Adaptation of biotechnology, etc. is possible. [Industrial Applicability]

[0271] The present disclosure is suitable for use as a communication device such as a base station, an access point, or a terminal. [Explanation of symbols]

[0272] 102, 155, 405, 452, 2901 Signal processing unit 104_1~104_M, 403_1~403_N Radio section 106_1~106_M, 401_1~401_N Antenna section 151 Receiving antenna group 153, 454 Radio Group 158, 409 Setting section 202 Distribution section 204_1~204_4, 503_1~503_4, 603_1~603_L Multiplication section 206_1~206_4, 303_1~303_K, 501_1~501_4, 601_1~601_L, 2903_1~2903_K Antenna 301, 2902 Weighting synthesis unit 456 transmitting antennas 605 Processing section 700, 1600 base stations 701~704, 901, 902, 2101~2104 Terminals 2900 Communication Equipment

Claims

1. A base station apparatus having a plurality of antenna elements, a signal processing unit that generates a plurality of transmission streams for a plurality of terminals to be transmitted in the same time period and in the same frequency band, and assigns each of the generated transmission streams to one of a plurality of subframes defined by time-frequency division of a frame; a weighting synthesis unit that applies weighting to the plurality of transmission streams; a transmitting unit that transmits a plurality of transmission signals obtained by the weighting from the plurality of antenna elements to the plurality of terminals; Equipped with a maximum number of transmission signals that can be simultaneously transmitted in the same time period and in the same frequency band is set to be larger as the communication range of the base station device to which each of the plurality of terminals belongs becomes smaller; A transmission stream not exceeding the maximum number of simultaneously transmittable transmission signals is assigned to each of the plurality of subframes in a manner that differs depending on the communication range. Base station equipment.

2. The transmitter transmits the plurality of transmission signals by directional transmission. The base station device according to claim 1 .

3. The outer edge of the communication range is defined by a distance from the base station device. The base station device according to claim 1 or 2.

4. In a first communication range, which is a communication limit when the base station device transmits a transmission signal of a first transmission beam number, a first transmission signal number, which is a maximum number of transmission signals that can be simultaneously transmitted in the same time period and in the same frequency band, is the second number of transmission signals is greater than the maximum number of transmission signals that can be simultaneously transmitted in the same time zone and in the same frequency band in a region excluding the first communication range within a second communication range that is a communication limit when the base station device transmits transmission signals having a second number of transmission beams that is smaller than the first number of transmission beams; The base station apparatus according to any one of claims 1 to 3.

5. the third number of transmission signals is a maximum number of transmission beams that can be simultaneously transmitted in the same time zone and the same frequency band in a region of the third communication range excluding the second communication range, the second number of transmission signals is greater than the third number of transmission signals; The base station device according to claim 4.

6. The communication range indicates a limit position where communication is possible when the base station device transmits a predetermined number of transmission signals. The base station apparatus according to any one of claims 1 to 5.

7. A communication method for a base station device having a plurality of antenna elements, comprising: generating a plurality of transmission streams for a plurality of terminals for transmission in the same time period and in the same frequency band; allocating each of the generated transmission streams to one of a plurality of subframes defined by time-frequency division of a frame; weighting the plurality of transmission streams; transmitting the plurality of transmission signals obtained by the weighting from the plurality of antenna elements to the plurality of terminals; a maximum number of transmission signals that can be simultaneously transmitted in the same time period and in the same frequency band is set to be larger as the communication range of the base station device to which each of the plurality of terminals belongs becomes smaller; A transmission stream not exceeding the maximum number of simultaneously transmittable transmission signals is assigned to each of the plurality of subframes in a manner that differs depending on the communication range. Communication methods.

8. The plurality of transmission signals are transmitted by directional transmission. The communication method according to claim 7.

9. The outer edge of the communication range is defined by a distance from the base station device. A communication method according to claim 7 or 8.

10. In a first communication range, which is a communication limit when the base station device transmits a transmission signal of a first transmission beam number, a first transmission signal number, which is a maximum number of transmission signals that can be simultaneously transmitted in the same time period and in the same frequency band, is the second number of transmission signals is greater than the maximum number of transmission signals that can be simultaneously transmitted in the same time zone and in the same frequency band in a region excluding the first communication range within a second communication range that is a communication limit when the base station device transmits transmission signals having a second number of transmission beams that is smaller than the first number of transmission beams; A communication method according to any one of claims 7 to 9.

11. the third number of transmission signals is a maximum number of transmission beams that can be simultaneously transmitted in the same time zone and the same frequency band in a region of the third communication range excluding the second communication range, the second number of transmission signals is greater than the third number of transmission signals; The communication method according to claim 10.

12. The communication range indicates a limit position where communication is possible when the base station device transmits a predetermined number of transmission signals. A communication method according to any one of claims 7 to 11.

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