JP2013251841A - Radio communication base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base station which can operate with a large cell.SOLUTION: A radio communication base station which communicates with user terminals, divides a cell to configure a plurality of areas. The radio communication base station stores a plurality of pieces of antenna weight for setting orientation corresponding to the plurality of areas, selects one of the plurality of pieces of orientation, and determines the antenna weight corresponding to the selected orientation. The radio communication base station holds the determined orientation for a predetermined time, and re-selects another one of the plurality of pieces of antenna weight after the predetermined time has passed to determine new orientation. Thereafter, the radio communication base station repeats the antenna weight selection procedure.

Description

  The present invention relates to a radio communication base station, and more particularly to a radio communication base station that expands a cell by directivity control.

As a background art in this technical field, there is a technique disclosed in Japanese Patent Laid-Open No. 2003-347992 (Patent Document 1). This publication states that “a wireless communication system calculates a condition regarding the number of transmission blocks for the receiving terminal 2 to be able to receive all blocks based on the total number of blocks of the broadcast channel and the number of transmission blocks. Based on the block unit time and the jurisdiction angle, the calculation unit 1j that calculates the condition related to the rotational angular velocity, and the base station 1 controls the beam to rotate at the rotational angular velocity determined based on the condition related to the rotational angular velocity. It has a beam control unit 1k ”.
As another background art, there is JP-A-10-173585 (Patent Document 2). This publication describes, for example, rotating directivity.

JP 2003-347992 A JP-A-10-173585

  In cellular radio communication, one base station can communicate with a terminal located in a certain finite range (cell). Since the number of base stations to be installed can be reduced as the cell becomes larger, a base station that can be operated in a larger cell is required. In order to enlarge the cell, it is only necessary to transmit the radio wave farther away. If the transmission power is increased, the radio wave reaches far away, but there are hardware limitations such as an increase in cost because the linearity of the power amplifier of the base station is maintained.

  On the other hand, there is a method of increasing the antenna gain by controlling the directivity of the antenna in order to allow radio waves to reach far away. However, although the antenna gain is high in a limited direction (directing direction), a direction in which the antenna gain is low occurs at the same time. Patent Document 1 describes a method of transmitting a control signal only in the antenna directivity direction and continuously rotating the antenna directivity direction. However, as shown below, wireless communication cannot be performed by expanding the cell by this method.

For example, in a system based on the premise that a time change of a radio wave propagation environment during wireless communication is small, such as a MIMO-OFDM (multiple-input and multiple-output-Orthogonal Frequency Division Multiplexing) system widely used in recent years. If the directivity direction is continuously changed, the communication characteristics deteriorate. Further, in order to continuously change the directivity direction, many antenna elements are required, which increases the cost and complicates signal processing for controlling the continuous change. Furthermore, a signal other than the notification information, for example, a data signal cannot be transmitted further.
In view of the above points, an object of the present invention is to provide a base station that can be operated in a larger cell.

In order to solve the above problems, the configuration described in the claims is adopted.
According to the solution of the present invention,
A plurality of antennas for transmitting radio waves in a directivity direction according to a plurality of areas into which the cell is divided;
An area selector for selecting a part of the plurality of areas at predetermined time intervals;
An antenna weight holding unit for holding an antenna weight for each antenna for setting a directivity direction corresponding to the plurality of areas, corresponding to the area, and determining an antenna weight corresponding to the area selected by the area selector; ,
A weight processing unit for creating an output signal from the antenna based on a transmission signal including one or both of a control signal and a data signal and the determined antenna weight;
From the antenna, a radio wave in a directivity direction according to the antenna weight is transmitted,
A radio communication base station is provided in which the directivity direction is switched every predetermined time.

  According to the present invention, it is possible to provide a base station that can be operated in a larger cell.

The figure which shows the example of the area | region division of the radio | wireless communications system of 1st Example. The figure which shows the example of a setting of the directivity direction of a 1st Example. The figure which shows the circuit diagram of the base station of a 1st Example. The figure which shows the example of the area | region division of the radio | wireless communications system of 2nd Example. The figure which shows the circuit diagram of the base station of a 2nd Example. The figure which shows the circuit diagram of the base station of the radio | wireless communications system of 3rd Example. The figure which shows the example of a setting of the directivity direction of a 4th Example. The figure which shows the circuit diagram of the base station of the radio | wireless communications system of 4th Example. The figure which shows the example of a setting of the directivity direction of a 5th Example. A setting example of the directivity direction when the directivity direction is changed one by one every time the index increases. The figure which shows the circuit diagram of the base station of the radio | wireless communications system of 6th Example. The example of the table | surface hold | maintained with the antenna weight holding | maintenance part 201. FIG. An example of a table held by the user location area holding unit 220. An example of user terminal arrangement.

Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
Embodiments will be described below with reference to the drawings.
1. Outline The present application includes a plurality of means for solving the above-described problem. To give an example, a radio communication base station that communicates with a user terminal, which divides a cell to form a plurality of regions, Holding a plurality of antenna weights for setting the directivity direction corresponding to the region, selecting one of the plurality of directivity directions to determine the corresponding antenna weight, and holding the determined directivity direction for a predetermined time Then, after the predetermined time, one of the plurality of antenna weights is reselected to determine the directivity direction, and thereafter the above antenna weight selection procedure is repeated.

2. Example 1
FIG. 1 is a diagram illustrating an example of area division in the wireless communication system according to the first embodiment.
The base station 100 provides a wireless communication service to the cell 110 (to a wireless terminal in the cell). The cell 110 is divided into regions 1, 2, and 3, for example. The base station 100 sets the directivity direction only in any one of the areas 1, 2, and 3. As a result, the radio wave transmission direction can be reduced to 1/3, so that the transmission power density is tripled, and the radio wave reach is extended accordingly. That is, the cell 110 can be enlarged.

  The base station may be referred to as a macro base station. Although FIG. 1 shows one base station, a plurality of base stations are arranged in the wireless communication system. Moreover, although the example which divides | segments a cell into three area | regions is shown, it can divide | segment into a several area | region not only this. In addition, the directing direction is not limited to one of the plurality of regions, and a part of the plurality of regions may be selected such that two or more regions are selected at a time.

FIG. 2 is a diagram illustrating an example of setting the directivity direction according to the first embodiment.
When the directivity direction is set to a certain area, radio waves do not reach other areas. In order to allow radio waves to reach all areas in the cell, the directivity direction is set in each area divided by time. FIG. 2 shows an example in which the directivity direction is set in the order of regions 1, 2, and 3.

  If the directivity direction changes during communication, communication characteristics generally deteriorate. In particular, in the MIMO-OFDM system that has been widely adopted in recent years, the communication characteristics are greatly deteriorated if the directivity direction is changed within the time of the OFDM symbol. In order to avoid this, switching of regions 1, 2, and 3 is controlled to be performed at the boundary of OFDM symbols. FIG. 2 shows a slot of a transmission signal, which corresponds to, for example, an OFDM symbol. In order to prevent region selection by switching of the directivity direction from occurring during the slot period, the change of the slot and the change of the directivity direction are controlled to be synchronized with the switching timing signal.

FIG. 3 is a diagram illustrating a circuit diagram of the base station according to the first embodiment.
The base station 100 of this embodiment includes, for example, area selectors 200 and 210, antenna weight holding units 201 and 211, a transmission processing unit 202, a reception processing unit 212, weight multiplication units 203 and 213, a transmission / reception switch 204, an antenna 205, and A timing control unit 214 is included.
The area selectors 200 and 210 are blocks for selecting a directivity direction (area). The area selector 200 selects the transmission directivity direction, and the area selector (reception side area selector) 210 selects the reception directivity direction. When the same directivity direction is selected for both transmission and reception, one area selector (for example, 200) can also serve as the operation of the other area selector (for example, 210).

  Antenna weights corresponding to the areas selected by the area selectors 200 and 210 are acquired from the antenna weight holding units 201 and 211. For example, the antenna weight holding units 201 and 211 input the identification information of the region selected from the region selectors 200 and 210, and output the antenna weight corresponding to the identification information of the selected region to the weight multiplication unit 203. The antenna weight holding unit 201 is for transmission, and the antenna weight holding unit 211 is for reception. If the same antenna weight is applied for transmission and reception, one antenna weight holding unit (for example, 201) can also serve as the operation of the other antenna weight holding unit (for example, 211).

  FIG. 12 is an example of a table held by the antenna weight holding units 201 and 211. Weights corresponding to individual antennas are held for the area selected in the directivity direction. With the antenna weight corresponding to the region, the directivity direction of the radio wave output from the antenna is directed to the region. The antenna weight holding units 201 and 211 search the input area from the table of FIG. 12 and output the corresponding antenna weight. The antenna weight value is set to a fixed value before the operation of the base station. In each of the following embodiments, the same antenna weight holding unit can be used.

The transmission processing unit 202 processes a signal input from an upper layer and converts it into a signal to be actually transmitted. The signal to be transmitted includes, for example, one or both of a control signal and a data signal. The processing in the transmission processing unit 202 includes transmission signal randomization, error correction coding, modulation processing, and the like.
A weight multiplication unit (weight processing unit) 203 multiplies the signal generated by the transmission signal processing unit 202 by the weight input from the antenna weight holding unit 201.

The transmission / reception switch 204 outputs the signal generated by the weight multiplier 203 toward the antenna 205 and outputs the signal input from the antenna 205 toward the weight multiplier 213. As the transmission / reception switch 204, a switch is used in the time multiple-duplex communication system, and a duplexer is used in the frequency multiple-duplex communication system.
A weight multiplication unit (reception side weight processing unit) 213 multiplies the signal input from the transmission / reception switch 204 and the weight input from the antenna weight holding unit 211.
The reception processing unit 212 processes the signal input from the weight multiplication unit 213 and outputs the result to the upper layer. The processing in the reception processing unit 212 includes demodulation processing of received signals, error correction decoding, cancellation of randomization, and the like.

  The timing control unit 214 controls processing timings of the region selector 200 and the transmission processing unit 202, and the region selector 210 and the reception processing unit 212. The timing control unit 214 controls the directing direction switching timing. According to the signal output from the timing control unit 214, the directivity of the radio wave is switched by switching the outputs of the area selectors 200 and 210. The transmission processing unit 202 and the reception processing unit also perform processing timing control according to the output signal of the timing control unit 214. The timing control unit 214 starts counting at the switching timing of the directivity direction, switches the directivity direction when the count value exceeds the threshold value, clears the count value, and restarts counting. The time during which the pointing direction is held in a certain direction can be controlled by the threshold value described above. As an example, the above-described threshold value can be set to an OFDM symbol time or a multiple thereof. As a result, the directivity direction is switched in synchronization with the transmission signal or the reception signal, so that radio waves can be transmitted to all areas in the cell while avoiding deterioration of communication characteristics caused by a change in the directivity direction. In addition, since the switching of the pointing direction is realized by switching the antenna weight, the processing is simple, and the circuit scale can be reduced as compared with the case where the pointing direction is continuously changed.

Note that the timing control units 214-1 and 224-2 described above may be provided inside the area selector 210, respectively. It is also possible to carry out area selection only by either transmission or reception. For example, when more advanced antenna weight processing is performed in the reception processing unit 212 during reception, the area selector 210, the antenna weight holding unit 211, the weight multiplication unit 213, and the timing control unit 214-2 can be omitted. It is.

3. Example 2
FIG. 4 is a diagram illustrating an example of area division in the wireless communication system according to the second embodiment.
This example is an example of expanding a cell of a radio communication system having a three-sector configuration. The base station 100 provides wireless communication services to the three cells 110, 111, and 112. Such a cell configuration is sometimes referred to as a three-sector configuration, and each cell is sometimes referred to as a sector. The cells 110, 111, and 112 are divided into regions 1, 2, and 3, respectively. For example, the areas in each sector selected by the area selector are selected so as not to be adjacent to each other. For example, the arrangement order of the area numbers (or identifiers) is given to each cell in the order of rotation around the base station in a specific direction. For example, the arrangement order of the area numbers is set to be the same in all cells 110, 111, 112 in a specific direction around the base station. For example, the base station 100 sets the directivity direction only in one of the areas 1, 2, and 3. At the same time, all sectors can select an area having the same area number and set the directivity direction of the transmission radio wave.

  In the three-sector configuration, there is a problem that communication characteristics deteriorate due to interference between adjacent sectors at the sector boundary. If the configuration of the present embodiment is adopted, regions having the same number are selected in all sectors and they are not adjacent to each other, so that it is difficult to cause mutual interference. Therefore, it is possible to reduce deterioration of communication characteristics due to interference at the sector boundary. In addition to the three sectors, an appropriate number of sectors may be provided.

FIG. 5 is a diagram illustrating a circuit diagram of the base station according to the first embodiment.
The base station of this embodiment includes area selectors 200 and 210, a timing control unit 214, and three sector processing units 215 corresponding to each sector.
Each sector processing unit includes antenna weight holding units 201 and 211, a transmission processing unit 202, a reception processing unit 212, weight multiplication units 203 and 213, a transmission / reception switch 204, and an antenna 205.

The sector processing units 215-1, 215-2, and 215-3 are blocks that process transmission / reception signals corresponding to three different sectors, respectively. The operations of the other functional blocks are the same as those in the first embodiment (FIG. 3), and thus description thereof is omitted.
The three sector processing units 215 share one area selector 200, 210. As a result, the same area is selected by the three sector processing units. Since the same number region is selected in all sectors and they are not adjacent to each other, it is difficult to cause mutual interference. Therefore, it is possible to reduce deterioration of communication characteristics due to interference at the sector boundary.
If the same antenna weight is used in each sector, the antenna weight holding units 201 and 211 in each sector processing unit 215 can be combined into one and shared by all sector processing units 215. .

4). Example 3
In the present embodiment, in a communication scheme employing MIMO-OFDM, antenna weight multiplication for a control signal and MIMO precoding for a data signal are applied separately, and the control signal and the data signal are multiplied by an optimum antenna weight. .

FIG. 6 is a diagram illustrating a circuit diagram of a base station of the wireless communication system according to the third embodiment.
The base station 100 of the present embodiment includes an area selector 200, an antenna weight holding unit 201, a transmission data processing unit 202, a reception data processing unit 212, a weight multiplication unit 203, a transmission / reception switch 204, an antenna 205, a transmission control signal processing unit 206, A reception control signal processing unit 216, a MIMO precoder 207, a MIMO decoder 217, a transmission OFDM processing unit (multiplexing unit) 208, and a reception OFDM processing unit (demultiplexing unit) 218 are provided. Further, the timing control unit in the first embodiment may be provided. In this embodiment and the following embodiments, the timing control unit will be described as being inside the area selector.

  The area selector 200 is a block for selecting a directivity direction. The area selector 200 selects the direction of transmission of the control signal. An antenna weight corresponding to the area selected by the area selector 200 is acquired from the antenna weight holding unit 201. The transmission control signal processing unit 206 processes the control signal input from the upper layer and converts it into a signal to be actually transmitted. The processing in the transmission control signal processing unit 206 includes randomization of transmission control signals, error correction coding, modulation processing, and the like. The weight multiplication unit 203 multiplies the signal generated by the transmission control signal processing unit 206 by the weight input from the antenna weight holding unit 201.

  The transmission data processing unit 202 processes the data signal input from the upper layer and converts it into a signal to be actually transmitted. The processing in the transmission data processing unit 202 includes transmission signal randomization, error correction coding, modulation processing, and the like. A MIMO precoder (data-oriented processing unit, MIMO processing unit) 207 applies a MIMO precoding process to the signal input from the transmission data processing unit 202. A process for controlling an appropriate directivity direction other than MIMO may be applied. Transmission OFDM processing section 208 assigns each signal input from weight multiplication section 203 and MIMO precoder 207 to subcarriers, applies a Fourier transform, and generates an OFDM symbol by adding a cyclic prefix. For example, the directivity changes depending on the subcarrier, and the directivity is determined for each of the control signal and the data signal.

The transmission / reception switch 204 outputs the signal (OFDM symbol) generated by the transmission OFDM processing unit 208 toward the antenna 205 and outputs the signal input from the antenna 205 toward the reception OFDM processing unit 218. As the transmission / reception switch 204, a switch is used in the time multiple-duplex communication system, and a duplexer is used in the frequency multiple-duplex communication system.
The reception OFDM processing unit 218 removes a cyclic prefix from the signal input from the transmission / reception switch 204, applies an inverse Fourier transform, and outputs a subcarrier signal. Here, an example in which the OFDM scheme is adopted for the uplink is shown, but the present invention is not limited to this. For example, when an SC-FDMA (Single-Carrier Frequency-Division Multiple Access) method is adopted, SC-FDMA reception processing may be applied here.

  A MIMO decoder (data-oriented processing unit, MIMO reception processing unit) 217 applies a MIMO decoding process to the signal input from the reception OFDM processing unit 218. Received data processing section 212 processes the signal input from MIMO decoder 217-1 and outputs the obtained data to the upper layer. The processing in the reception processing unit 212 includes demodulation processing of received signals, error correction decoding, cancellation of randomization, and the like.

The reception control signal processing unit 216 processes the signal input from the MIMO decoder 217-2 and outputs the obtained control signal to the upper layer. The reception processing unit 216 includes demodulation processing of received signals, error correction decoding, cancellation of randomization, and the like.
As described above, the present embodiment applies the antenna weight multiplication to the control signal and the MIMO precoding to the data signal separately in the communication scheme adopting MIMO-OFDM, and is optimal for each of the control signal and the data signal. It is possible to multiply the antenna weight.

Since the control signal transmitted by the base station is a signal received by all terminals in the cell, the antenna weight cannot be optimized for a specific terminal. On the other hand, since the data signal is a signal transmitted to a specific terminal, it is possible to apply an optimum antenna weight to the terminal. MIMO precoding is signal processing that applies such antenna weights. In this embodiment, the weight multiplication unit 203 performs switching of the antenna weight by directivity control on the control signal. For the data signal, the MIMO precoder 207 shows a method of applying MIMO precoding. As a result, the communication characteristics of the data signal can be improved.

5. Example 4
FIG. 7 is a diagram illustrating an example of setting the directivity direction according to the fourth embodiment.
In general, in wireless communication, there are a plurality of control signals to be notified to a terminal. For example, broadcast 1 and broadcast 2 in FIG. 7 indicate two types of control signals having different transmission cycles. These have different signal transmission cycles, and in the example of FIG. 7, the transmission cycle of broadcast2 is three times the transmission cycle of broadcast1. Since it is desirable that the control signal reaches the terminal as soon as possible, it is preferable to switch the directing direction every time the control signal is transmitted (every transmission cycle). FIG. 7 shows such a state of switching the directivity direction, and the numbers in the frame indicate the directivity direction. As can be seen from FIG. 7, when such control is performed, there may be cases where the directivity directions differ between broadcast 1 and broadcast 2. Therefore, it is necessary to separately control the directivity directions of broadcast 1 and broadcast 2. In this example, two types of control signals are shown, but there may be more than that.

FIG. 8 is a diagram illustrating a circuit diagram of a base station of the wireless communication system according to the fourth embodiment.
The base station of this embodiment includes area selectors 200-1 and 200-2, an antenna weight holding unit 201, a transmission data processing unit 202, a reception data processing unit 212, weight multiplication units 203-1 and 203-2, and a transmission / reception switch 204. , Antenna 205, transmission control signal processing sections 206-1 and 206-2, reception control signal processing section 216, MIMO precoder 207, MIMO decoder 217, transmission OFDM processing section 208, and reception OFDM processing section 218.

  The area selectors 200-1 and 200-2 are blocks for selecting the directivity directions of broadcast1 and broadcast2 having different transmission cycles. The area selectors 200-1 and 200-2 select the directivity direction of transmission of the broadcast1 and broadcast2 control signals. Antenna weights corresponding to the areas selected by the area selectors 200-1 and 200-2 are acquired from the antenna weight holding unit 201 and output to the weight multiplication units 203-1 and 203-2, respectively. The transmission control signal processing units 206-1 and 206-2 process the broadcast1 and broadcast2 control signals input from the higher layers, respectively, and convert them into signals to be actually transmitted. The processing in the transmission control signal processing units 206-1 and 206-2 includes transmission control signal randomization, error correction coding, modulation processing, and the like. Weight multiplication sections 203-1 and 203-2 multiply the signals generated by transmission control signal processing sections 206-1 and 206-2 and the weights input from antenna weight holding section 201, respectively.

  The transmission data processing unit 202 processes the data signal input from the upper layer and converts it into a signal to be actually transmitted. The transmission data processing unit 202 includes transmission signal randomization, error correction coding, modulation processing, and the like. The MIMO precoder 207 applies a MIMO precoding process to the signal input from the transmission data processing unit 202.

Transmission OFDM processing section 208 assigns inputs from weight multiplication sections 203-1 and 203-2 and MIMO precoder 207 to subcarriers, applies a Fourier transform, and generates an OFDM symbol by adding a cyclic prefix.
The transmission / reception switch 204 outputs the signal generated by the transmission OFDM processing unit 208 toward the antenna 205, and outputs the signal input from the antenna 205 toward the reception OFDM processing unit 218. As the transmission / reception switch 204, a switch is used in the time multiple-duplex communication system, and a duplexer is used in the frequency multiple-duplex communication system.

  The reception OFDM processing unit 218 removes a cyclic prefix from the signal input from the transmission / reception switch 204, applies an inverse Fourier transform, and outputs a subcarrier signal. Here, an example in which the OFDM scheme is adopted for the uplink is shown, but the present invention is not limited to this. For example, when the SC-FDMA scheme is adopted, SC-FDMA reception processing may be applied here. The MIMO decoder 217 applies a MIMO decoding process to the signal input from the reception OFDM processing unit 218. The reception processing unit 212 processes the signal input from the MIMO decoder 217 and outputs the obtained data to the upper layer. The processing in the reception processing unit 212 includes demodulation processing of received signals, error correction decoding, cancellation of randomization, and the like.

The reception control signal processing unit 216 processes the signal input from the MIMO decoder 217 and outputs the obtained control signal to the upper layer. The reception processing unit 216 includes demodulation processing of received signals, error correction decoding, cancellation of randomization, and the like.
In this embodiment, broadcast1 and broadcast2 have separate area selectors 200-1 and 200-2 for the two types of control signals, so that it is possible to separately control the directivity directions of broadcast1 and broadcast2. Yes.

Although two types of control signals are used here, there may be more types of control signals. In this case, the region selector 200, the transmission control signal processing unit 206, and the weight multiplication unit 203 are selected according to the types of control signals. Just prepare. Here, the types of control signals may be classified according to the transmission period, that is, a plurality of control signals having the same transmission period may be classified into one type (group). In this case, an area selector 200, a transmission control signal processing unit 206, and a weight multiplication unit 203 may be provided for each transmission cycle.

6). Example 5
FIG. 9 is a diagram illustrating an example of setting the directivity direction according to the fifth embodiment.
In general, in wireless communication, there are a plurality of control signals to be notified to a terminal. For example, broadcast 1 and broadcast 2 in FIG. 9 indicate two types of control signals having different transmission cycles. These have different signal transmission cycles, and in the example of FIG. 9, the transmission cycle of broadcast2 is three times the transmission cycle of broadcast1. The plurality of control signals may not be divided and transmitted, for example, when transmitted in the same packet. In that case, the configuration of the fourth embodiment cannot be taken. Circles written in broadcast 1 and broadcast 2 in FIG. 9 indicate the transmission timing of each control signal. The index is a serial number assigned to all transmission timings. antenna direction indicates the directivity set in this embodiment.

Here, a problem due to switching of the directivity direction will be described with reference to FIG.
FIG. 10 shows the setting of the directivity direction when the directivity direction is changed one by one each time the index increases. The directivity direction increases in order from 1 to 3, and increases from 1. At this time, when the directivity direction setting of the transmission timing of broadcast 2 is seen, it can be seen that the directivity direction is directed to the region 1 every time. Accordingly, there arises a problem that broadcast 2 is not sent to areas 2 and 3.

In the present embodiment, as shown in FIG. 9, the directivity direction of the transmission timing of broadcast 2 is assigned to all of the regions 1, 2, and 3, and it can be seen that the above-described problems have been solved. In the present embodiment, the above-described problem is solved by periodically adding an offset to the number indicating the directivity direction. Specifically, the directivity direction can be calculated by the equation 300 in FIG.
antenna direction =
mod (index + floor (index / PERIODICITY), N_DIRECTIONS) +1
In this example, PERIODICITY = 3 and N_DIRECTIONS = 3. Let PERIODICITY be the period for adding the offset, and N_DIRECTIONS be the number of regions that can be selected as the pointing direction. Compared with the equation 301 used for setting the directivity direction in FIG. 10, the addition of floor (index / PERIODICITY) changes the offset value for each period determined by PERIODICITY, thereby changing the set value of the directivity direction. ing. The floor (numerical value, reference value) is a function that returns a value that is rounded down to the nearest value among multiples of the reference value.

Note that the ratio of two transmission periods of the plurality of control signals (3: 1 in the example of FIG. 9 is 3), and the number of regions (3 in the example of FIG. 9) is: In the same case, the area shifted by the offset at the timing at which the transmission cycles overlap may be selected, and other areas may be selected as usual. Further, the offset is increased by 1 in the above example, but the present invention is not limited to this, and an offset having an appropriate value may be used.
The apparatus configuration of the base station is the same as that of the fourth embodiment, and the above processing can be performed by the area selector 200. This can solve the problem that an area where no control signal is transmitted occurs.

7). Example 6
In the present embodiment, communication is performed by selecting an optimal directivity direction in accordance with the region where the user terminal is located, thereby improving communication characteristics.
FIG. 11 is a diagram illustrating a circuit diagram of a base station of the wireless communication system according to the sixth embodiment.
The base station 100 according to this embodiment includes an area selector 200, an antenna weight holding unit 201, a transmission data processing unit 202, a reception data processing unit 212, weight multiplication units 203-1, 203-2, and 213, a transmission / reception switch 204, and an antenna 205. , Transmission control signal processing section 206, transmission OFDM processing section 208, reception OFDM processing section 218, user location area holding section 220, antenna weight search sections 221-1, 221-2, 221-3, user location area search section 222, A user location area update unit 223 and a user location area detection unit 224 are configured.

  Each area selector 200 is a block for selecting the directivity direction of the control signal, and outputs identification information of the selected directivity direction. The antenna weight search unit 221-1 refers to the table of the antenna weight holding unit 201 and outputs an antenna weight corresponding to the region in the directivity direction input from the region selector 200. The transmission control signal processing unit 206 processes the control signal input from the higher layer and converts it into a signal to be actually transmitted. The processing in the transmission control signal processing unit 206 includes randomization of transmission control signals, error correction coding, modulation processing, and the like. The weight multiplication unit 203-1 multiplies the signal generated by the transmission control signal processing unit 206 by the weight input from the antenna weight search unit 221-1 and outputs the result.

The user location area search unit 222 refers to the table of the user location area holding unit 220 and outputs the location area of the user (terminal) corresponding to the destination user ID (destination identification information) of the transmission data input from the upper layer. To do.
The antenna weight search unit 221-2 refers to the table of the antenna weight holding unit 201 and outputs an antenna weight corresponding to the area input from the user location area search unit 222.

  The transmission data processing unit 202 processes the data signal input from the upper layer and converts it into a signal to be actually transmitted. The processing in the transmission data processing unit 202 includes transmission signal randomization, error correction coding, modulation processing, and the like. The weight multiplication unit 203-2 multiplies the signal generated by the transmission data processing unit 202 by the weight input from the antenna weight search unit 221-2 and outputs the result.

Transmission OFDM processing section 208 assigns inputs from weight multiplication sections 203-1 and 203-2 to subcarriers, applies a Fourier transform, and generates an OFDM symbol by adding a cyclic prefix.
The transmission / reception switch 204 outputs the signal generated by the transmission OFDM processing unit 208 toward the antenna 205, and outputs the signal input from the antenna 205 toward the reception OFDM processing unit 218. As the transmission / reception switch 204, a switch is used in the time multiple-duplex communication system, and a duplexer is used in the frequency multiple-duplex communication system.

  The reception OFDM processing unit 218 removes a cyclic prefix from the signal input from the transmission / reception switch 204, applies an inverse Fourier transform, and outputs a subcarrier signal. Here, an example in which the OFDM scheme is adopted for the uplink is shown, but the present invention is not limited to this. For example, when the SC-FDMA scheme is adopted, SC-FDMA reception processing may be applied here.

The user location region detection unit 224 extracts a signal corresponding to the reception allocation user ID input from the upper layer from the signals input from the reception OFDM processing unit 218, detects the arrival direction of the extracted signal, and applies Outputs the area identifier in the pointing direction.
The user location area update unit 223 displays the table of the user location area holding unit 220 based on the reception allocation user ID input from the upper layer and the area information output from the user location area detection unit 224 correspondingly. Update.

  The antenna weight search unit 221-3 refers to the table of the antenna weight holding unit 201 and outputs an antenna weight corresponding to the region input from the user location region detection unit 224. The weight multiplication unit 213 multiplies the signal input from the reception OFDM processing unit 218 and the weight input from the antenna weight search unit 221-3 and outputs the result. The reception processing unit 212 processes the signal input from the weight multiplication unit 213 and outputs the obtained data to the upper layer. The processing in the reception processing unit 212 includes demodulation processing of received signals, error correction decoding, cancellation of randomization, and the like.

  Switching of the directivity direction of the transmission control signal is performed by switching the output of the area selector 200. For example, similarly to the above, the area selector 200 starts counting at the time when the directing direction is switched, switches the directing direction when the count value exceeds a predetermined threshold value, clears the count value, and then restarts counting. To do. The switching of the pointing direction typically changes the area in order. Alternatively, the directivity direction may be switched by the method of the fifth embodiment.

FIG. 13 is an example of a table held by the user location area holding unit 220. This table is an example assuming the arrangement of the user terminals shown in FIG. In FIG. 14, 100 is a base station, 110 is a cell, and 120-x is a user terminal (user ID = x).
The user location area search unit 222 searches the table of FIG. 13 for the input user ID and outputs the corresponding location area. The table of the user location area holding unit 220 is empty at the time of initialization, the user ID is added by the user location area update unit 223, and the location area is updated. When it is determined that the user terminal is no longer located in the cell, such as when the user terminal moves to another cell due to handover, or when communication with the user terminal is interrupted for a certain period of time, The corresponding user ID is deleted from the table of the location area holding unit 220.

According to the above method, it is possible to perform communication by selecting an optimal directivity direction according to the region where the user terminal is located, and to improve communication characteristics.
The hardware required for the radio communication base station according to the present application is the same as that of the conventional radio communication base station using the MIMO-OFDM method, and can be realized only by changing the signal processing method. For example, in the case of a wide-area disaster or the like, when it is desired to obtain a wide communicable area with a small number of base stations, it is preferable to apply the method of the present application.

8). Application example [Application example 1]
The radio communication base station is, for example,
A plurality of antennas for transmitting radio waves in a directivity direction according to a plurality of areas into which the cell is divided;
An area selector for selecting a part of the plurality of areas at predetermined time intervals;
An antenna weight holding unit for holding an antenna weight for each antenna for setting a directivity direction corresponding to the plurality of areas, corresponding to the area, and determining an antenna weight corresponding to the area selected by the area selector; ,
A weight processing unit for creating an output signal from the antenna based on a transmission signal including one or both of a control signal and a data signal and the determined antenna weight;
From the antenna, radio waves in the directivity direction according to the antenna weight are sent out,
At each predetermined time, the directivity direction is switched.
As a result, the transmission direction of radio waves is narrowed to one of a plurality of areas instead of all directions, so that the transmission power density is increased and the reach of the radio waves is extended accordingly. Thereby, the cell 110 which a base station covers can be expanded, and the base station which can be operated by a larger cell can be provided.

[Application Example 2]
In the radio communication base station described in Application Example 1,
A timing control unit is further provided for controlling so that the switching of the region by the region selector is performed at a slot or OFDM symbol boundary.
Thereby, since the directivity direction does not change within the symbol time of OFDM, it is possible to prevent deterioration of communication characteristics.

[Application Example 3]
In the radio communication base station described in Application Example 1,
The wireless communication base station has a plurality of sectors, each sector is divided into the plurality of regions,
The areas in each sector selected by the area selector are selected so as not to be adjacent to each other.
Thus, the present invention can be applied to a multi-sector configuration. Further, in the cells adjacent to each other, the regions can be sequentially selected so that the selected regions are not adjacent to each other, and interference can be hardly caused.

[Application Example 4]
In the radio communication base station described in Application Example 3,
The plurality of regions in each cell is given an identifier for each cell in the order of rotation around the base station in a specific direction,
The region selector sequentially selects the regions so that the identifiers of the regions selected in the cells are the same in all the cells.
Accordingly, by selecting the areas according to such a rule, the areas can be sequentially selected so that the selected areas are not adjacent to each other, and interference with each other can be reduced.

[Application Example 5]
In the radio communication base station described in Application Example 1,
The weight processing unit multiplies the control signal by the determined antenna weight to create an output signal,
Wireless communication base station
A data-oriented processing unit for controlling a directivity direction with respect to a data signal;
It further includes a multiplexing unit that multiplexes the control signal from the weight processing unit and the data signal from the data-oriented processing unit and outputs the multiplexed signal to the antenna.
Thereby, the optimal antenna weight can be multiplied to each of the control signal and the data signal.

[Application Example 6]
In the radio communication base station described in Application Example 1,
The weight processing unit multiplies the control signal by the determined antenna weight to create an output signal,
Wireless communication base station
A MIMO processing unit for performing MIMO processing on the data signal;
It further includes a multiplexing unit that multiplexes the control signal from the weight processing unit and the data signal from the MIMO processing unit and outputs the multiplexed data signal to the antenna.
Thereby, MIMO can be applied to the data signal, and the optimal antenna weight can be multiplied to each of the control signal and the data signal.

[Application Example 7]
In the radio communication base station described in Application Example 1,
The control signal includes a plurality of control signals having different transmission cycles,
The region selector individually sets the directivity direction by the antenna weight for each of the plurality of control signals,
For each control signal, a region is selected such that the region is changed for each corresponding transmission cycle.
As a result, the directivity direction of each control signal is switched every transmission cycle, and the control signal can be transmitted evenly without being biased in a specific direction.

[Application Example 8]
In the radio communication base station described in Application Example 1,
The control signal includes a plurality of control signals having different transmission cycles,
The plurality of control signals are transmitted in a pointing direction corresponding to the selected area,
The region selector sequentially selects regions according to a predetermined rule, and selects a region shifted from the rule by a predetermined offset at a timing at which different transmission periods of control signals overlap.
As a result, it is possible to avoid a situation in which any one of the plurality of control signals is transmitted only to a specific area and not transmitted to another area. For example, even when a plurality of control signals are transmitted in the same packet, it is possible to avoid a situation where any one of the control signals is transmitted only to a specific area and not transmitted to another area.

[Application Example 9]
In the radio communication base station described in Application Example 8,
When the ratio of the two transmission periods of the plurality of control signals is the same as the number of the plurality of regions, the region shifted by the offset at the timing is selected.
Thereby, when the ratio of the two transmission periods of the plurality of control signals is the same as the number of the plurality of regions, it is possible to prevent transmission of only one control signal to one region.

[Application Example 10]
In the radio communication base station described in Application Example 1,
It further comprises a multiplexing unit that multiplexes the control signal and the data signal,
For the control signal and data signal, set the directivity direction by the antenna weight separately,
The directivity direction set for the data signal is set to be the directivity direction where the user terminal that is the transmission destination of the data signal is located.
Thereby, the optimal directivity direction can be selected for the data signal according to the region where the user terminal is located, and the directivity direction can be selected so that the control signal is sequentially transmitted to each region.

[Application Example 11]
In the radio communication base station described in Application Example 1,
A reception-side weight processing unit that multiplies the reception signals received via the plurality of antennas and the determined antenna weight; and a reception processing unit that demodulates the signal output from the reception-side weight processing unit,
The selected region is switched every predetermined time.
As a result, processing using the antenna weight can be performed also on the reception side. The area selector and the antenna weight holding unit can be shared with the transmission side.

[Application Example 12]
In the radio communication base station described in Application Example 11,
A receiving area selector that selects a part of the plurality of areas at predetermined time intervals;
A reception-side antenna that holds an antenna weight for each antenna for setting a directivity direction corresponding to the plurality of regions, corresponding to the region, and determines an antenna weight corresponding to the region selected by the reception-side region selector A weight holding portion,
The reception-side weight processing unit uses the antenna weight determined by the reception-side antenna weight holding unit.
As a result, processing using the antenna weight can be performed also on the reception side. The area selector and the antenna weight holding unit can be configured differently from the transmission side.

9. In addition, this invention is not limited to the Example mentioned above, Various modifications are included. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Information such as programs, tables, and files for realizing each function can be stored in a storage device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card or a DVD. It is also possible to download the program via a network or the like and install it in various storage devices.
Further, the present invention can be used for, for example, a base station that communicates with a wireless terminal.

DESCRIPTION OF SYMBOLS 100 Base station 110-112 Cell 120 Terminal 200, 210 Area selector 201, 211 Antenna weight holding | maintenance part 202 Transmission processing part 203, 213 Weight multiplication part 204 Transmission / reception switch 205 Antenna 206 Transmission control signal processing part 207 MIMO precoder 208 Transmission OFDM processing part 212 reception processing unit 214 timing control unit 215 sector processing unit 216 reception control signal processing unit 217 MIMO decoder 218 reception OFDM processing unit 220 user location region holding unit 221 antenna weight search unit 222 user location region search unit 223 user location region update unit 224 User location area detector

Claims (12)

A plurality of antennas for transmitting radio waves in a directivity direction according to a plurality of areas into which the cell is divided;
An area selector for selecting a part of the plurality of areas at predetermined time intervals;
An antenna weight holding unit for holding an antenna weight for each antenna for setting a directivity direction corresponding to the plurality of areas, corresponding to the area, and determining an antenna weight corresponding to the area selected by the area selector; ,
A weight processing unit for creating an output signal from the antenna based on a transmission signal including one or both of a control signal and a data signal and the determined antenna weight;
From the antenna, a radio wave in a directivity direction according to the antenna weight is transmitted,
A radio communication base station in which a directivity direction is switched every predetermined time. The radio communication base station according to claim 1, further comprising a timing control unit configured to control so that switching of a region by the region selector is performed at a slot or OFDM symbol boundary. The wireless communication base station has a plurality of sectors, each sector is divided into the plurality of regions,
The radio communication base station according to claim 1, wherein areas in each sector selected by the area selector are selected so as not to be adjacent to each other. The plurality of regions in each cell is given an identifier for each cell in the order of rotation around the base station in a specific direction,
The radio communication base station according to claim 3, wherein the area selector sequentially selects areas such that identifiers of areas selected in the cells are the same in all cells. The weight processing unit generates an output signal by multiplying the control signal by the determined antenna weight,
Wireless communication base station
A data-oriented processing unit for controlling a directivity direction with respect to a data signal;
The radio communication base station according to claim 1, further comprising a multiplexing unit that multiplexes a control signal from the weight processing unit and a data signal from the data-oriented processing unit and outputs the multiplexed signal to an antenna. The weight processing unit generates an output signal by multiplying the control signal by the determined antenna weight,
Wireless communication base station
A MIMO processing unit for performing MIMO processing on the data signal;
The radio communication base station according to claim 1, further comprising a multiplexing unit that multiplexes a control signal from the weight processing unit and a data signal from the MIMO processing unit and outputs the multiplexed signal to an antenna. The control signal includes a plurality of control signals having different transmission periods,
The region selector individually sets a directivity direction by the antenna weight for each of the plurality of control signals,
The radio communication base station according to claim 1, wherein an area is selected so that the area is changed for each corresponding transmission cycle for each control signal. The control signal includes a plurality of control signals having different transmission periods,
The plurality of control signals are transmitted in a pointing direction corresponding to the selected area,
2. The radio communication base station according to claim 1, wherein the area selector sequentially selects areas according to a predetermined rule, and selects an area shifted by a predetermined offset from the rule at a timing at which different transmission periods of control signals overlap. .   The radio communication base station according to claim 8, wherein a region shifted by an offset at the timing is selected when a ratio of two transmission periods of a plurality of control signals is equal to the number of the plurality of regions. It further comprises a multiplexing unit that multiplexes the control signal and the data signal,
For the control signal and data signal, set the directivity direction by the antenna weight separately,
The radio communication base station according to claim 1, wherein a directivity direction set for the data signal is set to be a directivity direction in which a user terminal that is a transmission destination of the data signal is located. A reception side weight processing unit that multiplies the reception signals received via the plurality of antennas and the determined antenna weight; and a reception processing unit that demodulates the signal output from the reception side weight processing unit,
The radio communication base station according to claim 1, wherein a selected area is switched at each predetermined time. A receiving area selector that selects a part of the plurality of areas at predetermined time intervals;
A reception-side antenna that holds an antenna weight for each antenna for setting a directivity direction corresponding to the plurality of regions, corresponding to the region, and determines an antenna weight corresponding to the region selected by the reception-side region selector A weight holding portion,
The radio communication base station according to claim 11, wherein the reception side weight processing unit uses an antenna weight determined by the reception side antenna weight holding unit.

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