JP2010263651A - Transmitter and transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce transmission power and to make a device smaller in scale by distributedly transmitting signals not subjected to variable directivity transmission from respective antennas of an array antenna, when the variable directivity transmission is performed only on a part of terminals. <P>SOLUTION: Signals subjected to variable directivity transmission are multiplied by weight coefficients for antennas 101-103 by a multiplication circuit 152 and then are output to synthesis circuits 155-157. First of signals which are not subjected to variable directivity transmission is output to the synthesis circuit 155; a second is output to the synthesis circuit 156; a third is output to the synthesis circuit 157; and a fourth one is output to the synthesis circuit 155. The synthesis circuits 155-157 synthesize the received signals, the synthesized signals are radio-modulated by radio units 104-106 respectively, and the modulated signals are transmitted from the antennas 101-103, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transmission apparatus and a transmission method used in a digital radio communication system that performs directional transmission using an adaptive array antenna in a downlink.

  A digital wireless communication system such as a mobile phone or a car phone has a cellular system in which a communication area is divided into cells, one base station device is placed in each cell, and a plurality of terminal devices simultaneously communicate with the base station device. Adopted. In recent years, cellular systems have rapidly spread and the number of system users has increased rapidly, so it has become an important issue to increase channel capacity in one cell.

  One technique for increasing the channel capacity is an adaptive array antenna. As described in “Waveform equalization technology for digital mobile communications” (supervised by Satoshi Horikoshi, Trikeps Co., Ltd.), an adaptive array antenna has an amplitude at each antenna output of an array antenna composed of multiple antennas.・ By using the fact that the directivity of the array is formed by adding a phase shift and combining, the weighting factor of each antenna output is determined based on a predetermined control algorithm and adapted to changes in the surrounding conditions. It is a technology that controls directivity.

  By applying the adaptive array antenna to the uplink and removing the interference from other cells to improve the reception quality, it is possible to increase the channel capacity of the uplink.

  In addition, the adaptive array antenna is applied to the downlink, the base station apparatus estimates the signal arrival direction from the target terminal apparatus, and performs directional transmission in the estimated direction, thereby maintaining the channel quality while maintaining the channel quality. Since transmission power from the apparatus can be reduced and interference with other terminal apparatuses can be reduced, it is possible to increase the channel capacity of the downlink.

  Here, in the downlink, if the direction of signal arrival is estimated for all terminal apparatuses with which the base station apparatus performs communication and directional transmission is performed, the amount of signal processing increases, resulting in a problem that the apparatus scale increases.

  For this reason, the conventional transmission apparatus mounted on the base station apparatus uses the array antenna for directivity using a part of terminal apparatuses such as a terminal apparatus that performs high-speed data transmission or a terminal apparatus that requires large transmission power. Non-directional transmission such as sector transmission or omni transmission using an antenna prepared separately from the array antenna or one of the array antennas for other terminal devices (hereinafter referred to as “omnidirectional transmission”). ").

  As a result, the channel capacity can be increased without significantly increasing the device scale of the signal processing unit. Further, by performing directional transmission, it is possible to reduce transmission power in an array antenna that performs only directional transmission.

  However, in the conventional transmission apparatus, a plurality of signals to be omnidirectionally transmitted are combined and transmitted from one antenna, so the transmission power at this antenna is not reduced. Therefore, there is a problem in that the dynamic range during the amplification operation of the radio unit cannot be suppressed, and a large-sized amplifier that generates a large amount of heat must be used.

  The present invention has been made in view of such a point, and in a base station apparatus that performs directional transmission only to a part of terminal apparatuses, the required power in the amplifier in the radio unit is suppressed, and the apparatus scale is reduced. It is an object of the present invention to provide a transmission device and a transmission method that can be achieved.

  The transmitter according to the first aspect of the present invention includes a plurality of antennas, a weighting unit that performs weighting for directional transmission on a plurality of signal components generated from the first signal, and the weighted unit Transmission control means for performing control to transmit a plurality of signal components using the plurality of antennas and to transmit a second signal using any one of the plurality of antennas, and the transmission control The means adopts a configuration in which one of the plurality of weighted signal components is controlled to be transmitted simultaneously with the second signal using the one antenna.

  In the receiving device according to the second aspect of the present invention, the transmitting device weights a plurality of signal components generated from the first signal for directional transmission, and transmits the second signal to the plurality of antennas. The plurality of weighted signals so that one of the plurality of weighted signal components is transmitted simultaneously with the second signal using the one antenna. The signal component transmitted using the plurality of antennas is received.

  A transmitting apparatus according to a third aspect of the present invention includes a plurality of antennas, a weighting unit that performs weighting for directional transmission on a plurality of signal components generated from a first signal, and the weighted unit A transmission control unit configured to transmit a plurality of signal components using the plurality of antennas and to transmit a second signal using any one of the plurality of antennas.

  According to the present invention, since the omnidirectional transmission signal can be distributed to each antenna of the array antenna, the transmission power of each antenna can be distributed, and the transmission power can be larger than the other antennas can be eliminated. The amplifier in the radio unit can be downsized. This also means that the phase rotation width at the time of signal amplification is reduced, and it is effective for simplifying the radio unit calibration required for the adaptive array antenna.

System diagram of a wireless communication system including a base station device equipped with the transmission device of the present invention FIG. 3 is a block diagram showing a configuration of a base station apparatus in the first embodiment Block diagram showing a configuration of a base station apparatus in Embodiment 2

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a system diagram showing a radio communication system including a base station apparatus equipped with a transmission apparatus according to the present invention.

  The base station apparatus 11 of FIG. 1 plays the role of a communication repeater, processes a signal wirelessly transmitted from the terminal apparatus, and transmits the signal to the external network 21 wirelessly or via a wired transmission. The signal is processed and wirelessly transmitted to each terminal device.

  Here, the base station apparatus 11 in FIG. 1 includes three antennas 101, 102, and 103, and performs simultaneous communication with five terminal apparatuses. The terminal apparatus 1, the terminal apparatus 2, the terminal apparatus 3, and the terminal apparatus 4, omnidirectional transmission is performed, and directional transmission is performed to the terminal device 5.

(Embodiment 1)
FIG. 2 is a block diagram of a configuration of the base station apparatus according to the first embodiment. The base station apparatus 11 shown in FIG. 2 includes three antennas 101, 102, and 103, radio units 104, 105, and 106, a transmission unit 107, a reception unit 108, and signal processing units 109, 110, 111, and 112. , 113. The transmission unit 107 includes a weight coefficient control unit 151, multiplication circuits 152, 153, 154, and synthesis circuits 155, 156, 157.

  The radio unit 104 converts the high-frequency signal received by the antenna 101 into a baseband signal and outputs the baseband signal to the reception unit 108, and converts the baseband signal input from the synthesis circuit 155 into a high-frequency signal and transmits the radio signal from the antenna 101. Send. The radio unit 105 converts the high frequency signal received by the antenna 102 into a baseband signal and outputs the baseband signal to the reception unit 108, and converts the baseband signal input from the synthesis circuit 156 into a high frequency signal and transmits the radio signal from the antenna 102. Send. The radio unit 106 converts the high frequency signal received by the antenna 103 into a baseband signal and outputs the baseband signal to the reception unit 108, and also converts the baseband signal input from the synthesis circuit 157 into a high frequency signal and transmits the radio signal from the antenna 103. Send.

  The transmission unit 107 distributes, combines, and outputs the transmission signals for the terminal devices input from the signal processing units to the radio units. The receiving unit 108 demodulates the baseband signal input from each radio unit, extracts and synthesizes the received signal from each terminal device, and outputs the combined signal to each signal processing unit. Further, the receiving unit 108 estimates the arrival direction of the reception signal (hereinafter referred to as “fifth reception signal”) from the terminal device 5 that has been directionally received, and outputs information related to the arrival direction to the signal processing unit 113.

  The signal processing unit 109 decodes the received signal from the terminal device 1 (hereinafter referred to as “first received signal”) input from the receiving unit 108 and outputs the decoded signal to the external network, and the terminal device 1 input from the external network. A transmission signal (hereinafter referred to as “first transmission signal”) is encoded and modulated, and output to the synthesis circuit 155.

  The signal processing unit 110 decodes the reception signal from the terminal device 2 (hereinafter referred to as “second reception signal”) input from the reception unit 108 and outputs the decoded signal to the external network, and the terminal device 2 input from the external network. A transmission signal (hereinafter referred to as “second transmission signal”) is encoded and modulated, and is output to the synthesis circuit 156.

  The signal processing unit 111 decodes the reception signal from the terminal device 3 (hereinafter referred to as “third reception signal”) input from the reception unit 108 and outputs the decoded signal to the external network, and the terminal device 3 input from the external network. A transmission signal (hereinafter referred to as “third transmission signal”) is encoded and modulated, and output to the synthesis circuit 157.

  The signal processing unit 112 decodes the reception signal from the terminal device 4 (hereinafter referred to as “fourth reception signal”) input from the reception unit 108 and outputs the decoded signal to the external network, and the terminal device 4 input from the external network. A transmission signal (hereinafter referred to as “fourth transmission signal”) is encoded and modulated, and output to the synthesis circuit 155.

  The signal processing unit 113 decodes the fifth reception signal input from the reception unit 108 and outputs the decoded signal to the external network. Also, the signal processing unit 113 transmits a transmission signal to the terminal device 5 input from the external network (hereinafter referred to as “fifth transmission signal”). Are modulated and output in parallel to each multiplication circuit. In addition, the signal processing unit 113 outputs information on the arrival direction input from the reception unit 108 to the weighting coefficient control unit 151.

  The weighting factor control unit 151 calculates the weighting factor of each antenna output based on the information regarding the arrival direction input from the signal processing unit 113, and outputs the calculated weighting factor to each multiplication circuit. The multiplier circuit 152 multiplies the fifth transmission signal by the weight coefficient input from the weight coefficient control unit 151 and outputs the result to the synthesis circuit 155. The multiplier circuit 153 multiplies the fifth transmission signal by the weight coefficient input from the weight coefficient control unit 151 and outputs the result to the synthesis circuit 156. The multiplier circuit 154 multiplies the fifth transmission signal by the weight coefficient input from the weight coefficient control unit 151 and outputs the result to the synthesis circuit 157.

  The combining circuit 155 combines the signals input from the signal processing unit 109, the signal processing unit 112, and the multiplication circuit 152 and outputs the combined signal to the wireless unit 104. The combining circuit 156 combines the signals input from the signal processing unit 110 and the multiplication circuit 153 and outputs the combined signals to the wireless unit 105. The combining circuit 157 combines the signals input from the signal processing unit 111 and the multiplication circuit 154 and outputs the combined signals to the wireless unit 106.

  Next, the flow of received signals from each terminal apparatus in the base station apparatus 11 of FIG. 2 will be described.

  A signal received from the antenna 101 is converted from a high frequency signal to a baseband signal by the radio unit 104 and output to the receiving unit 108. Similarly, a signal received from the antenna 102 is converted from a high frequency signal to a baseband signal by the radio unit 105, and a signal received from the antenna 103 is converted from a high frequency signal to a baseband signal by the radio unit 106, respectively. It is output to 108.

  The receiving unit 108 demodulates the baseband signal from each radio unit, extracts the received signal from each terminal device, performs diversity combining including adaptive array antenna processing, and further directivity. The direction of arrival of the received fifth received signal is estimated.

  The first received signal is decoded by the signal processing unit 109 and transmitted to an external network system. Similarly, the second received signal is decoded by the signal processing unit 110, the third received signal is decoded by the signal processing unit 111, the fourth received signal is decoded by the signal processing unit 112, and the fifth received signal is decoded by the signal processing unit. The data is decrypted by 113 and transmitted to an external network system.

  Further, the information regarding the arrival direction estimated by the receiving unit 108 is output to the weighting coefficient control unit 151 via the signal processing unit 113. Then, the weighting factor control unit 151 calculates the weighting factor of the fifth transmission signal based on the information related to the arrival direction, and outputs the calculated weighting factor to the multiplying circuits 152, 153, and 154.

  Next, the flow of transmission signals for each terminal apparatus in the base station apparatus 11 of FIG. 2 will be described.

  The first transmission signal is encoded and modulated by the signal processing unit 109 and output to the synthesis circuit 155. The second transmission signal is encoded and modulated by the signal processing unit 110 and output to the synthesis circuit 156. The third transmission signal is encoded and modulated by the signal processing unit 111 and output to the synthesis circuit 157. The fourth transmission signal is encoded and modulated by the signal processing unit 112 and output to the synthesis circuit 155.

  The fifth transmission signal is encoded and modulated by the signal processing unit 113. The modulated fifth transmission signal is multiplied by a weighting factor for the antenna 101 by the multiplication circuit 152 and output to the synthesis circuit 155. Similarly, the modulated fifth transmission signal is multiplied by the weighting coefficient for the antenna 102 by the multiplication circuit 153 and output to the combining circuit 156, and is multiplied by the weighting coefficient for the antenna 103 by the multiplication circuit 154. Is output.

  The signals input to the combining circuit 155 are combined, wirelessly modulated by the wireless unit 104, and transmitted through the antenna 101. The signals input to the combining circuit 156 are combined, wirelessly modulated by the wireless unit 105, and transmitted through the antenna 102. The signals input to the combining circuit 157 are combined, wirelessly modulated by the wireless unit 106, and transmitted through the antenna 103.

  In this way, signals other than directional transmission are distributed to each antenna of the array antenna and transmitted, so that the transmission power of the antenna can be distributed. The scale of the amplifier can be reduced. In addition, since the phase rotation width at the time of signal amplification becomes small, it is effective in simplifying the radio unit calibration required for the adaptive array antenna.

(Embodiment 2)
FIG. 3 is a block diagram of a configuration of the base station apparatus according to the second embodiment. In the base station apparatus shown in FIG. 3, portions common to the base station apparatus shown in FIG.

  The base station apparatus shown in FIG. 3 adopts a configuration in which a switch control unit 201 and connection switches 202 to 213 are added to the base station apparatus of FIG.

  The switch control unit 201 controls each connection switch so that the transmission power of each antenna is uniform based on the transmission power for each terminal device input from each signal processing unit and the weighting factor input from the weighting factor 151. . The connection switches 202 to 213 are connected or disconnected under the control of the switch control unit 201.

  Hereinafter, as an example, the transmission power for the terminal device 1 is 1.0, the transmission power for the terminal device 2 is 1.5, the transmission power for the terminal device 3 is 1.8, the transmission power for the terminal device 4 is 2.2, and the terminal The transmission power to the device 5 is 2.0, the weighting factor output to the multiplication circuit 152 is 0.5, the weighting factor output to the multiplication circuit 153 is 0.3, and the weighting factor output to the multiplication circuit 154 is 0. The control of the switch control unit 201 in the case of 2 will be described.

  First, the switch control unit 201 multiplies the transmission power of the directional transmission signal by a weighting factor to calculate the transmission power of each antenna of the directional transmission signal. In this example, the transmission power of the antenna 101 to the terminal device 5 is 1.0, the transmission power of the antenna 102 to the terminal device 5 is 0.6, and the transmission power of the antenna 103 to the terminal device 5 is 0.4.

  Next, antennas that transmit omnidirectional transmission signals are allocated so that the transmission power of each antenna is uniform. In this example, the first transmission signal is transmitted from the antenna 103, the second transmission signal is transmitted from the antenna 103, the third transmission signal is transmitted from the antenna 101, and the fourth transmission signal is transmitted from the antenna 102. As a result, the transmission power of the antenna 101 is 2.8, the transmission power of the antenna 102 is 2.8, the transmission power of the antenna 103 is 2.9, and the difference in transmission power between the antennas is minimized.

  Finally, the switch control unit 201 controls each connection switch based on the antenna allocation result. In this example, the connection switches 204, 207, 208, and 212 are connected, and the other connection switches are disconnected.

  Note that the switch control unit 201 appropriately controls connection switches in accordance with changes in transmission power and weighting factors for each terminal device.

  Thus, by allocating the transmission signal for each terminal device to each antenna so that the transmission power of each antenna is approximately the same, the size of the device can be further reduced as compared with the first embodiment.

  In the second embodiment, the antenna for transmitting a signal other than the directional transmission is selected by switch switching. However, instead of using the switch control unit and the connection switch, the weight coefficient control unit and the multiplication circuit are used, It can also be performed by control. In this case, the weight coefficient control unit sets one of the output weight coefficients to “1” and the other to “0”. Inputting the weighting factor “1” to the multiplication circuit is equivalent to connecting a connection switch, and the signal input to the multiplication circuit is output as it is. Also, inputting the weight coefficient “0” to the multiplication circuit is equivalent to disconnecting the connection switch, and nothing is output from the multiplication circuit.

  Thereby, each signal processing part can process either an omnidirectional transmission signal or a directional transmission signal. Specifically, each signal processing unit, when processing a directional transmission signal, causes the weighting factor control unit to output a weighting factor based on information on the arrival direction, and when processing a omnidirectional transmission signal, The control unit is caused to output a weight coefficient “1” or “0”.

  Note that the present invention can be applied to any system in which directional transmission and omnidirectional transmission are mixed, and is not limited by a signal multiplex division scheme or the like.

1, 2, 3, 4, 5 Terminal device 11 Base station device 21 External network 101, 102, 103 Antenna 104, 105, 106 Radio unit 107 Transmitting unit 108 Receiving unit 109, 110, 111, 112, 113 Signal processing unit 151 Weight coefficient control unit 152, 153, 154 Multiplication circuit 155, 156, 157 Synthesis circuit 201 Switch control unit

Claims (4)

Multiple antennas,
Weighting means for weighting the first signal for directional transmission from the plurality of antennas;
Allocating means for allocating a plurality of second signals not directionally transmitted to the plurality of antennas;
Transmitting means for simultaneously transmitting the first signal weighted by the weighting means and the plurality of second signals allocated by the allocation means using the plurality of antennas;
The allocating means allocates so that the difference between the maximum value and the minimum value of the number of second signals transmitted using each antenna is 1 or less.
Transmitter device. Weighting the first signal for directional transmission from multiple antennas;
Allocating a plurality of second signals not transmitting directional to the plurality of antennas;
A transmission method of simultaneously transmitting the weighted first signal and the plurality of allocated second signals using the plurality of antennas,
The allocation is performed such that the difference between the maximum value and the minimum value of the number of second signals transmitted using each antenna is 1 or less.
Transmission method. Allocate multiple signals not directional transmission to multiple antennas,
Transmitting the plurality of allocated signals using the plurality of antennas;
Transmission method. Allocate multiple signals to multiple antennas,
Transmitting the plurality of allocated signals using the plurality of antennas;
Transmission method.

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