JP2020061762A - Power transmission device, power reception device and communication method using the same - Google Patents

Abstract

To provide a power transmission device, executing spatial multiplex transmission using a plurality of array antenna elements, capable of improving power efficiency by following beams in an optimum direction, adaptively and highly precisely according to environmental changes and/or movement of a communication partner.SOLUTION: A power transmission device 100 superposes reference signals which are known in a power reception device of a communication partner, whose patterns are different from each other and whose number are the same as antenna elements 110, on a transmission signal after phase adjustment for each of the antenna elements 110, and transmits the superposed signal from each of the antenna elements 110.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transmitting device that transmits a signal to a communication partner by spatial multiplex transmission using a plurality of antenna elements, a communication partner of the transmitting device, and a receiving device that receives the signal transmitted from the transmitting device, and the receiving device. About the communication method that was.

  Conventionally, there is known a technique for improving frequency utilization efficiency by spatially multiplexing and transmitting data by using an array antenna including a plurality of antenna elements (for example, Patent Document 1). In particular, in recent years, a technique called Massive MIMO, which spatially multiplexes and transmits data using an array antenna including a large number of antenna elements, has been receiving attention. The communication using sub-millimeter waves to millimeter waves capable of securing a wide band is compatible with Massive MIMO including a large number of antenna elements because the antenna size and the antenna interval can be reduced. Massive MIMO is one of important elemental technologies in the fifth generation wireless communication system (5G).

  In Massive MIMO, it is possible to realize spatial multiplexing and improve power efficiency by adjusting the phases of a large number of antenna elements and directing narrow beams to a communication partner.

Japanese Patent Publication No. 2006-504354

  In a device that spatially multiplexes and transmits data using an array antenna, it is necessary to adjust the phase between antenna elements to form a beam due to variations in parts or variations in the wiring length between the device body and the antenna. is there. Also, when the communication partner moves or when there is a physical position change of the antenna element due to environmental changes such as wind or vibration, the beam initially set is not optimal, so the phase adjustment is adaptively performed. It is necessary to go to form the beam.

  In 5G, which uses a high-frequency band that has high straightness and has a characteristic that radio waves are hard to fly, it is necessary to form a narrow beam to transmit data in order to obtain a predetermined communication distance, so the beam is accurately formed. Is especially important.

  However, heretofore, there has not been disclosed a technique for adaptively and immediately controlling the beam to accurately and accurately follow the optimum direction according to environmental changes and movement of a communication partner during communication in Massive MIMO transmission.

  An object of the present invention is to adaptively and instantly accurately and accurately follow a beam in an optimum direction according to a change in environment and movement of a communication partner during communication of spatial multiplex transmission by a multi-antenna such as Massive MIMO, and power consumption. It is an object of the present invention to provide a transmitter and a receiver that can improve efficiency and a communication method using them.

  A transmitting device according to the present invention is a transmitting device for transmitting a signal to a receiving device of a communication partner by spatial multiplex transmission using a plurality of antenna elements, the antenna being known in the receiving device and having different patterns from each other. A reference signal generation unit that generates the same number of reference signals as the number of elements, and for each antenna element, based on feedback information including information based on the reception timing of each of the reference signals in the past by the reception device, data and pilot symbols are generated. A phase adjustment unit that adjusts the phase of the transmission signal that includes, and an addition that superimposes the reference signals different from each other on the phase-adjusted transmission signal for each antenna element and outputs the same number of superimposed signals as the antenna element. And a wireless transmission unit that wirelessly transmits each of the superimposed signals from a corresponding antenna element. Sent from the amplitude of each transmission signal is almost the same, the amplitude of the reference signal is a one substantially identical said transmission signal.

  A receiving device according to the present invention is a communication partner of the above transmitting device, is a receiving device that receives a signal transmitted from the transmitting device, and a demodulation unit that demodulates a received signal to extract data, and the receiving device. A correlator that performs a correlation calculation on each of the reference signals with respect to a signal, and a correlator that detects the reception timing of each of the reference signals, and a transmission that transmits feedback information including information based on the reception timing of each of the reference signals to the transmission device And a section.

  A communication method according to the present invention is a communication method in which a transmission device having a plurality of antenna elements transmits a signal to a reception device by spatial multiplexing transmission, and the transmission device is known in the reception device and has patterns mutually Different steps of generating the same number of reference signals as the antenna elements, adjusting the phase of a transmission signal including data and pilot symbols for each antenna element, and transmitting the phase adjusted for each antenna element Each of the antennas has a step of superimposing different reference signals on the signal and outputting the same number of superposed signals as the number of the antenna elements, and a step of wirelessly transmitting each of the superposed signals from a corresponding antenna element. The amplitudes of the respective transmission signals transmitted from the elements are substantially the same, and the amplitude of the reference signal is approximately the same as that of the transmission signals. It is the same, and the receiving device receives the signal transmitted from the transmitting device, demodulates the received signal to extract data, and performs a correlation operation on the received signal with respect to each of the reference signals. , A step of detecting the reception timing of each of the reference signals, and a step of transmitting feedback information including information based on the reception timing of each of the reference signals to the transmission device, the transmission device, the phase In the adjusting step, the phase of the transmission signal is adjusted based on the feedback information received from the receiving device.

  According to the present invention, it is possible to improve the power efficiency by adaptively and instantaneously accurately and accurately following the beam in the optimum direction according to the environmental change or the movement of the communication partner during the communication of the spatial multiplex transmission. .

The figure which shows the structure of the communication system which concerns on Embodiment 1 of this invention. Block diagram showing a configuration of a transmission apparatus according to Embodiment 1 of the present invention Block diagram showing the configuration of the phase calculator according to the first embodiment of the present invention Block diagram showing a configuration of a receiving apparatus according to Embodiment 1 of the present invention Flowchart showing the operation of the communication system according to the first embodiment of the present invention The figure which shows the slot format of the transmission signal which concerns on Embodiment 1 of this invention. The figure which shows the slot format of the received signal which concerns on Embodiment 1 of this invention. The figure which shows the output signal of the correlator which concerns on Embodiment 1 of this invention. The figure which shows the structure of the modification of the communication system which concerns on Embodiment 1 of this invention. The figure which shows the structure of the modification of the communication system which concerns on Embodiment 1 of this invention. Flowchart showing the operation of the communication system according to the first embodiment of the present invention Block diagram showing the configuration of a transmitting apparatus according to Embodiment 2 of the present invention The figure which shows the slot format of the transmission signal which concerns on Embodiment 2 of this invention. The figure which shows the slot format of the received signal which concerns on Embodiment 2 of this invention. The figure which shows the output signal of the correlator which concerns on Embodiment 2 of this invention. Block diagram showing the configuration of a transmitting apparatus according to Embodiment 3 of the present invention Block diagram showing the configuration of a receiving apparatus according to Embodiment 4 of the present invention

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
<Communication system configuration>
The configuration of the communication system according to the first embodiment of the present invention will be described in detail below with reference to FIG.

  The communication system includes one transmitting device 100, M (M is a natural number) receiving devices 200, and a base station 300.

  The transmitting device 100 is a base station of a micro cell having a cell radius smaller than that of a macro cell, is connected to the base station 300 by a wired or wireless link, and is wirelessly connected to the receiving device 200. Transmitting apparatus 100 performs directional transmission of a transmission signal including pilot symbols and user data by spatial multiplex transmission using an array antenna including N (N is a natural number) antenna elements, to receiving apparatus 200. In addition, the transmitting device 100 non-directionally transmits the reference signal from each antenna element to the receiving device 200. In addition, the transmission device 100 receives feedback information from the reception device 200 via the base station 300, and performs directivity control based on the received feedback information.

  Each receiving device 200 is a communication partner of the transmitting device 100, and receives a signal including the pilot symbol and the user data directionally transmitted from the transmitting device 100. Further, the receiving device 200 receives the reference signal transmitted from the transmitting device 100. Then, receiving apparatus 200 generates feedback information created based on the received reference signal and transmits it to base station 300.

  The base station 300 is a macrocell base station, receives the feedback information transmitted from the receiving device 200, and transfers the received feedback information to the transmitting device 100.

<Structure of transmitter>
The configuration of transmitting apparatus 100 according to the present embodiment will be described below in detail with reference to FIG.

  The transmission device 100 includes a timing control unit 101, a reference signal generation unit 102, N modulation units 103-1 to 103-N, M transmission signal generation units 104-1 to 104-M, and M modulation signals. Modulators 105-1 to 105-M, M × N phase shifters 106-1-1 to 106-M-N, M phase calculators 107-1 to 107-M, and N phase shifters Of the wireless communication units 109-1 to 109-N, and N antenna elements 110-1 to 110-N. The N antenna elements 110-1 to 110-N form an array antenna.

  The timing control unit 101 notifies the reference signal generation unit 102 of the timing of outputting the reference signal, and outputs the transmission signal #k (k is an integer satisfying 1 ≦ k ≦ M) at the timing of generating each transmission signal. Notify the unit 104-k.

  The reference signal generator 102 generates the same number of reference signals # 1 to #N as the number N of antenna elements. The reference signal generator 102 outputs each generated reference signal #j (j is an integer satisfying 1 ≦ j ≦ N) to each modulator 103-j at the timing notified from the timing controller 101. Here, each reference signal #j is a pattern signal which is known in the receiving apparatus 200 and is different from each other, such as an orthogonal spreading code or a PN pattern. The reference signals #j are preferably orthogonal to each other.

  Each modulator 103-j modulates the reference signal #j output from the reference signal generator 102 and outputs the modulated reference signal #j to the wireless transmitter 109-j.

  Each transmission signal generation unit 104-k generates a transmission signal #k including the pilot symbol #k and user data #k, and transmits the transmission signal #k to the modulation unit 105-k at the timing notified from the timing control unit 101. Output.

  Each modulator 105-k modulates the transmission signal #k output from the transmission signal generator 104-k and outputs it to the phase shifters 106-k-1 to 106-k-N.

  Each phase shifter 106-k-j outputs the transmission signal #k output from the modulator 105-k based on the phase correction amount calculated by the phase calculator 107-k for each antenna element 110-j. Phase shift. The phase shifters 106-1-j to 106-M-j output the phase-shifted transmission signal #k to the adder 108-j.

  For each antenna element 110-j, each phase calculator 107-k determines the phase for maintaining the optimum directivity based on the channel estimation value based on the reception timing of each reference signal #j in the past by the receiving apparatus 200. Calculate the correction amount. The phase calculator 107-k outputs the correction amount of the phase to the phase shifters 106-k-1 to 106-k-N. The details of the configuration of the phase calculator 107-k will be described later.

  Each addition unit 108-j adds the transmission signals # 1-j to # M-j output from the phase shifters 106-1-j to 106-M-j for each antenna element 110-j, and adds them. The subsequent transmission signal #j is output to the wireless transmission unit 109-j.

  Each wireless transmission unit 109-j inserts the reference signal output from the modulation unit 103-j into the transmission signal #j output from the addition unit 108-j, performs wireless processing such as amplification and up-conversion, Radio transmission is performed from the antenna element 110-j. As a result, the transmission signal #k is directionally transmitted.

<Configuration of phase calculator>
Next, the configuration of the phase calculator 107-k according to the present embodiment will be described in detail below with reference to FIG.

  The phase calculator 107-k has N tap coefficient multiplication units 121, N channel estimation value calculation units 122, an addition unit 123, a comparison unit 124, and a correction amount calculation unit 125. There is.

  Each tap coefficient multiplication unit 121-j multiplies the input random signal by the tap coefficient #j, and outputs it to the channel estimation value calculation unit 122-j. Further, each tap coefficient multiplication unit 121-j sequentially corrects the tap coefficient #j according to an instruction from the correction amount calculation unit 125.

  The channel estimation value calculation unit 122-j uses the random signal output from the tap coefficient multiplication unit 121-j to artificially calculate the channel estimation value indicating the channel fluctuation of the propagation path, and outputs the channel estimation value to the addition unit 123. .

  The addition unit 123 adds the channel estimation values output from the channel estimation value calculation unit 122-j, and outputs the addition result to the comparison unit 124.

  The comparison unit 124 compares the channel estimation value output from the addition unit 123 with the information indicating the channel estimation value included in the feedback information, and outputs the comparison result to the correction amount calculation unit 125 as error information.

  The correction amount calculation unit 125 uses a LMS (Least Mean Square) algorithm, an RLS (Recursive Least Squares) algorithm, or the like based on the error information output from the comparison unit 124, and the correction amount of the phase that reduces the error. And the tap coefficient are calculated, the phase correction amount is output to the phase shifters 106-k-1 to 106-k-N, and the tap coefficient is instructed to the tap coefficient multiplication unit 121-j.

<Structure of receiving device>
Next, the configuration of receiving apparatus 200 according to the present embodiment will be described below in detail with reference to FIG.

  The receiving device 200 includes an antenna 201, a wireless receiving unit 202, a demodulating unit 203, N correlators 204, and a transmission control information calculating unit 205.

  The radio reception unit 202 performs radio processing such as amplification and down conversion on the reception signal received by the antenna 201, and outputs the reception signal to the demodulation unit 203 and correlators 204-1 to 204-N.

  Demodulation section 203 performs channel estimation using pilot symbols included in the received signal output from radio receiving section 202, and uses channel estimation values to compensate for channel fluctuations in data symbols. After that, the demodulation unit 203 demodulates the data symbols and extracts the data.

  Each correlator 204-j is a sliding correlator or the like, performs a correlation operation between the received signal output from the wireless reception unit 202 and the known pattern of the reference signal #j, and outputs the correlation value to the transmission control information calculation unit 205. Is output. In addition, when the transmitting device 100 and the receiving device 200 are not moving bodies, the correlators 204-1 to 204-N may be configured to be removable except at the time of initial setting or maintenance.

  Transmission control information calculation section 205 detects the reception timing of reference signals # 1 to #N based on the correlation values output from correlators 204-1 to 204-N, performs channel estimation based on the reception timing, Feedback information including information indicating a channel estimation value is generated and transmitted to base station 300.

<Operation of communication system>
Next, the operation of the communication system 1 according to the present embodiment will be described with reference to FIG.

  First, the transmitter 100 transmits each reference signal # 1 to #N from each antenna element 110-1 to 110-N (S1).

  The receiving device 200-k of the user #k establishes timing synchronization using the received reference signals # 1 to #N (S2). Timing synchronization can be established if the correlation value can be obtained only for one pattern of the reference signal #j.

  Next, the reception device 200-k performs sliding correlation based on the established synchronization timing, and performs channel estimation for all reference signals # 1 to #N (S3).

  Next, the reception device 200-k generates feedback information including information indicating the channel estimation value, and transmits the feedback information to the transmission device 100 via the base station 300 (S4).

  Next, the transmission device 100 performs directivity control on the user data #k based on the feedback information received from the reception device 200-k via the base station 300, and the user data downlink to the reception device 200-k. #K is transmitted (S5).

  The receiving device 200-k receives the downlink user data #k from the transmitting device 100. Further, the receiving device 200-k transmits the uplink user data #k to the base station 300 (S6).

  The base station 300 receives the data #k from the receiving device 200-k (S7). After that, steps S5 to S7 are repeated until the communication of the receiving device 200-k ends (YES in S8).

<Slot format>
FIG. 6 is a diagram showing a slot format of a transmission signal according to the present embodiment. FIG. 7 is a diagram showing a slot format of a received signal according to the present embodiment. FIG. 8 is a diagram showing an output signal of the correlator 204-k. 6 and 7, pilot symbols # 1 to #M will be simply referred to as pilots.

  As illustrated in FIG. 6, the transmission apparatus 100 multiplex-transmits pilot symbols # 1 to #M from each antenna element 110-j for each slot between times t1 and t2, and between times t2 and t3. The reference signal #j is transmitted, and the user data # 1 to #M are multiplexed and transmitted between times t3 and t4. At this time, transmitting apparatus 100 controls directivity so that pilot symbol #k and user data #k are received by receiving apparatus 200-k at the maximum reception level.

  In this case, as shown in FIG. 7, receiving apparatus 200-k receives pilot symbols # 1 to #M during times t1 'to t2'. However, since the directivity of the transmission signal from the transmission device 100 is controlled, the reception device 200-k receives the pilot symbol #k at a relatively high reception level as compared with other pilot symbols that cause interference. can do. Similarly, the reception device 200-k can receive the user data #k at a relatively high reception level as compared with other user data that causes interference during the time t3 'to t4'. Although the receiving device 200-k receives the reference signals # 1 to #N during the times t2 'to t3', it does not use these signals for demodulation processing or the like and discards them.

  FIG. 8 is a diagram showing an output signal of the correlator 204-k. As shown in FIG. 8, when the correlation between the received signal and the known pattern of the reference signal #j is calculated, the correlation value becomes a very high value at the reception timing of the reference signal #j as compared with the others. Therefore, receiving apparatus 200-k can estimate the reception timing of reference signal #j based on the correlation value, and can perform channel estimation.

  As described above, according to the present embodiment, transmitting apparatus 100 transmits the same number of reference signals as antenna elements 110, which are known to the communication partner and have different patterns, after phase adjustment for each antenna element 110. It is inserted in the transmission signal, and the transmission signal and the reference signal are transmitted from each antenna element 110. Further, transmitting apparatus 100 calculates the phase for forming directivity based on the feedback information including the information indicating the channel estimation value from the communication partner, and adjusts the phase of the transmission signal. With this, during the communication of the spatial multiplex transmission, the beam can be immediately and accurately followed in the optimum direction according to the environmental change or the movement of the communication partner, and the power efficiency can be improved.

  In addition, although the case where the feedback information is transmitted from the receiving apparatus 200 to the transmitting apparatus 100 via the base station 300 has been described above, the present embodiment is not limited to this, and as shown in FIG. The present invention can also be applied to the case of omnidirectional direct wireless transmission from the receiving device 200 to the transmitting device 100. Further, in the present embodiment, as shown in FIG. 10, a one-to-one entrance line (two communication devices have a one-to-one communication in which each of the two communication devices has the function of the transmitting device 100 and the function of the receiving device 200) is provided. Can also be applied.

Further, although the case where the tap coefficient sequentially corrected by the phase calculator 107-k is calculated has been described above, in the present embodiment, as the configuration of the phase calculator 107-k, [tap coefficient matrix] = [line [Estimation matrix] ^-1 as a configuration for obtaining a channel estimation value by a ZF (Zero forcing) method, or [Tap coefficient matrix] = [Channel estimation matrix] + [noise matrix] ^-1 as MMSE (Minimum mean square error) The line estimation value may be obtained. Alternatively, tap coefficient candidates may be stored in advance, and a tap coefficient corresponding to the calculated channel estimation value may be selected and included in the feedback information. In this case, the feedback information can be easily generated and the circuit scale can be reduced.

  Further, although the case where the apparatus 100 transmits the reference signal in all the slots has been described above, in the present embodiment, the reference signal is included in the slot and transmitted only when the directivity needs to be updated. You may do it. FIG. 11 is a flow chart in this case. 11, in the flow of FIG. 5, step S11 is inserted between step S4 and step S5, step S12 is inserted between step S7 and step S8, and further, step S13, The step of S14 is inserted.

  After S4, the transmitter 100 stops transmitting the reference signals # 1 to #N (S11). Then, the device 100 performs directivity control on the user data #k based on the feedback information received in the past, and transmits the downlink user data #k to the receiving device 200-k (S5).

  After S7, the reception device 200-k determines whether or not the directivity needs to be changed based on the reception quality (S12). When the reception quality is good and the directivity does not need to be updated (S12: NO), the flow proceeds to S8. On the other hand, when the reception quality is poor and the directivity needs to be updated (S12: YES), the receiving device 200-k transmits a directivity control request to the device 100 (S13). Upon receiving the directivity control request, the device 100 again transmits the reference signals # 1 to #N (S14). After this, the flow returns to S3.

  Note that FIG. 11 illustrates the case where the receiving device 200-k determines whether or not the directivity needs to be updated, and transmits the directivity control request. However, in the present embodiment, the directivity The transmission device 100 may determine whether the update is necessary.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In addition, in the present embodiment, the configuration of the communication system is the same as that of FIG. 1 described in the first embodiment, and therefore the description thereof is omitted. In addition, in the present embodiment, the configuration of the receiving apparatus is the same as that of FIG. 4 described in Embodiment 1, so description thereof will be omitted. Further, in the present embodiment, the operation of the communication system has the same configuration as that of FIG. 5 and FIG. 11 described in the first embodiment, and therefore the description thereof will be omitted.

<Structure of transmitter>
The configuration of transmitting apparatus 400 according to the present embodiment will be described below in detail with reference to FIG. In FIG. 12, the same components as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

  The transmitting apparatus 400 shown in FIG. 12 is different from the transmitting apparatus 100 shown in FIG. 2 in the functions of the addition units 108-1 to 108-N and the wireless transmission units 109-1 to 109-N. .

  Each modulator 103-j modulates the reference signal #j output from the reference signal generator 102 and outputs it to each adder 108-j.

  Each adder 108-j adds the transmission signals # 1-j to # M-j output from the phase shifters 106-1-j to 106-M-j for each antenna element 110-j, and further , And superimposes the reference signal #j output from the modulator 103-j, and outputs the superimposed signal #j to the wireless transmitter 109-j. At this time, the amplitude (transmission power) of each transmission signal # 1-j to # M-j is almost the same, and the amplitude of the reference signal #j is one of the transmission signals # 1-j to # M-j. It is almost the same.

  Each wireless transmission unit 109-j performs wireless processing such as amplification and up-conversion on the superimposed signal #j output from the addition unit 108-j, and wirelessly transmits from the antenna element 110-j. As a result, the transmission signal #k is directionally transmitted. On the other hand, the reference signal #j is omnidirectionally transmitted from each antenna element 110-j.

<Slot format>
FIG. 13 is a diagram showing a slot format of a transmission signal according to this embodiment. FIG. 14 is a diagram showing a slot format of a received signal according to the present embodiment. Note that, in FIGS. 13 and 14, pilot symbols # 1 to #M are simply described as pilots.

  As illustrated in FIG. 13, the transmission device 400 multiplex-transmits pilot symbols # 1 to #M from each antenna element 110-j between times t11 and t13 for each slot, and between times t13 and t15. User data # 1 to #M are multiplexed. At this time, transmitting apparatus 100 controls directivity so that pilot symbol #k and user data #k are received by receiving apparatus 200-k at the maximum reception level. Furthermore, in the present embodiment, transmitting apparatus 400 refers to pilot symbols # 1 to #M or user data # 1 to #M from time t12 to time t14 from each antenna element 110-j for each slot. Signal #j is superimposed and omnidirectionally transmitted. At this time, in the transmission antenna #j, the amplitude of each transmission signal #j is almost the same, and the amplitude of the reference signal #j is almost the same as one of the transmission signals #j.

  In this case, receiving apparatus 200-k receives pilot symbols # 1 to #M during times t11 'to t13'. However, since the directivity of the transmission signal from the transmission device 100 is controlled, the reception device 200-k receives the pilot symbol #k at a relatively higher reception level than other pilot symbols that cause interference. can do. Similarly, the reception apparatus 200-k can receive the user data #k at a relatively high reception level as compared with other user data that causes interference during the times t13 'to t15'.

By the directional transmission, the amplitude becomes N times and the power becomes N ² times that of the desired transmission destination (reception device 200-k), while the phase of each element becomes the other transmission destination. Since the power is N times because it is random, the DU ratio (Signal-to-Noise ratio) is N. For example, if N = 100, the DU ratio is 20 dB, and if N = 400, the DU ratio is 26 dB.

  In addition, the reference signals # 1 to #N are received by the receiving device 200-k between times t12 and t14. The reference signals # 1 to #N act as interference during demodulation, but have almost no influence because they are omnidirectionally transmitted with low transmission power.

  By superimposing the reference signal, the number of multiplexing is increased by one. When the number of multiplexing becomes M + 1, the DU ratio becomes N / M. For example, if N = 100 and M = 10, the DU ratio will be 10 dB. Further, if the reference signal is lengthened, the amplitude can be suppressed, so that it is possible to reduce interference.

  FIG. 15 is a diagram showing an output signal of the correlator 204-k. As shown in FIG. 15, when the correlation between the received signal and the known pattern of the reference signal #j is calculated, the correlation value is much higher than the others at the reception timing of the reference signal #j as in FIG. Becomes Therefore, receiving apparatus 200-k can estimate the reception timing of reference signal #j based on the correlation value, and can perform channel estimation.

  As described above, according to the present embodiment, transmitting apparatus 400 transmits the same number of reference signals as antenna elements 110, which are known to the communication partner and have different patterns, after phase adjustment. The superimposed signal is superimposed on the transmission signal, and the superimposed signal is transmitted from each antenna element 110. Further, transmitting apparatus 400 calculates the phase for forming directivity based on the feedback information including the information indicating the channel estimation value from the communication partner, and adjusts the phase of the transmission signal. As a result, during MIMO transmission communication, the beam can be immediately and accurately followed in the optimum direction in response to changes in the environment and movement of the communication partner, and power efficiency can be improved.

  Further, in the present embodiment, reference signals # 1 to #M are transmitted by superimposing and transmitting pilot signals # 1 to #M and user data # 1 to #M, thereby transmitting reference signals # 1 to #M. It is possible to eliminate the dedicated resource (time) for the purpose, and improve the transmission efficiency of the user data # 1 to #M.

  Further, in the present embodiment, the transmission periods of reference signals # 1 to #M can be lengthened so that they are superposed over the entire slot. The longer the transmission period of the reference signals # 1 to #M, the more accurate the channel estimation can be performed.

  Further, in the present embodiment, pilot symbols # 1 to #M are set to a fixed pattern, and reference signals # 1 to #N are set to be orthogonal to pilot symbols # 1 to #M, so that the pilot symbols are used at the time of correlation processing. Since it is possible to reduce the influence of the interference of the above, the channel estimation value for each antenna element 110-j can be obtained with higher accuracy.

  Further, although the case where the apparatus 400 transmits the reference signal in all the slots has been described above, in the present embodiment, the reference signal is included in the slot and transmitted only when the directivity needs to be updated. This may be done (see FIG. 11).

(Embodiment 3)
Next, a third embodiment of the invention will be described. In addition, in the present embodiment, the configuration of the communication system is the same as that of FIG. 1 described in the first embodiment, and therefore the description thereof is omitted. In addition, in the present embodiment, the configuration of the receiving apparatus is the same as that of FIG. 4 described in Embodiment 1, so description thereof will be omitted. Further, in the present embodiment, the operation of the communication system has the same configuration as that of FIG. 5 and FIG. 11 described in the first embodiment, and therefore the description thereof will be omitted.

<Structure of transmitter>
The configuration of transmitting apparatus 500 according to the present embodiment will be described below in detail with reference to FIG. In FIG. 16, the same components as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

  Compared with the transmission device 100 shown in FIG. 2, the transmission device 500 shown in FIG. 16 has FIR filters 501-1-1 to 501-M instead of the phase shifters 106-1-1 to 106-MN. -N, and tap coefficient calculators 502-1 to 502-M are provided instead of the phase calculators 107-1 to 107-M.

  Each modulator 105-k modulates the transmission signal #k output from the transmission signal generator 104-k and outputs the modulated transmission signal #k to the FIR filters 501-k-1 to 501-k-N.

  Each FIR filter 501-k-j forms a filter with the tap coefficient calculated by the tap coefficient calculator 502-k for each antenna element 110-j, and transmits the transmission signal #k output from the modulator 105-k. The phase of the transmission signal #k is adjusted by passing it through the filter. The FIR filters 501-1-j to 501-M-j output the phase-shifted transmission signal #k to the addition unit 108-j.

  Each tap coefficient calculator 502-k, for each antenna element 110-j, a tap coefficient for forming directivity based on the channel estimation value based on the reception timing of each reference signal #j in the past by the receiving apparatus 200. To calculate. The tap coefficient calculator 502-k outputs the tap coefficient to the FIR filters 501-k-1 to 501-k-N.

  As described above, according to this embodiment, the same effect as that of the first embodiment can be obtained.

  Further, in the present embodiment, the functions of adding sections 108-1 to 108-N and the functions of radio transmitting sections 109-1 to 109-N of transmitting apparatus 500 may be changed as described in the second embodiment. In this case, the same effect as the second embodiment can be obtained.

  Note that when estimating the tap coefficient, past history can also be used. In this case, the directivity control can be converged early by storing the tap coefficient estimated in the past and the position information in association with each other. Further, by successively estimating the tap coefficient and observing the change, the tap coefficient can be used for estimating the moving speed of the receiving device. Further, by analyzing the tap coefficient and comparing it with the past one, the position or direction of the receiving device, the obstacle or the like can be estimated.

(Embodiment 4)
Next, a fourth embodiment of the invention will be described. Embodiment 4 describes a case where the receiving device has a plurality of antenna elements.

  In addition, in the present embodiment, the configuration of the communication system is the same as that of FIG. 1 described in the first embodiment, and therefore the description thereof is omitted. In addition, in the present embodiment, the configuration of the transmitting apparatus is the same as that of FIG. 2 described in Embodiment 1, so description thereof will be omitted. Further, in the present embodiment, the operation of the communication system has the same configuration as that of FIG. 5 and FIG. 11 described in the first embodiment, and therefore the description thereof will be omitted.

<Structure of receiving device>
The configuration of receiving apparatus 600 according to the present embodiment will be described below in detail with reference to FIG.

  The receiving device 600 includes L antennas 601-1 to 601-L, L radio receiving units 602-1 to 602-L, and L + N-1 correlators 603-1 to 603-1. It has N, 603-2 to 603-L, the transmission control information calculation part 604, L FIR filters 605-1 to 605-L, the addition part 606, and the demodulation part 607.

  Each radio reception unit 602-i (i is an integer that satisfies 1 ≦ i ≦ L) performs radio processing such as amplification and down conversion on the reception signal received by the antenna 601-i, and the correlator 603-is provided. i and FIR filter 605-i. The wireless reception unit 602-1 outputs the received signal after the wireless processing to the correlators 603-1-1 to 603-1-N.

  The correlators 603-1-1 to 603-1-N perform correlation calculation between the received signal output from the wireless reception unit 602-1 and the known patterns of the reference signals # 1 to #M to calculate a correlation value. , And outputs the calculated correlation value to the transmission control information calculation unit 604. The correlator 603-1-1 also outputs the calculated correlation value to the FIR filter 605-1.

  The correlator 603-i (in this case, i is other than 1) performs a correlation operation between the received signal and the known pattern of the reference signal # 1 to calculate a correlation value, and the calculated correlation value is sent to the FIR filter 605-i. Output.

  The transmission control information calculation unit 604 detects the reception timing of the reference signals # 1 to #N based on the correlation value output from the correlators 603-1-1 to 603-1-N, and the line based on the reception timing. The estimation is performed, feedback information including information indicating the channel estimation value is generated, and the feedback information is transmitted to the base station 300.

  The FIR filter 605-i uses the correlation value output from the correlator 603-i (in the case of i = 1, the correlator 603-1-1) to convert the received signal output from the wireless reception unit 602-i. On the other hand, filtering processing (compensation for line fluctuation) is performed and the result is output to the addition unit 606.

  The adding unit 606 adds the filtered received signals output from the FIR filters 605-1 to 605-L to perform maximum ratio combining, and then outputs the result to the demodulating unit 607.

  Demodulation section 607 performs channel estimation using the pilot symbols included in the added reception signals output from addition section 606, and compensates the channel fluctuation of the data symbols using the channel estimation value. Then, demodulation section 607 demodulates the data symbols and extracts the data.

  As described above, according to the present embodiment, when the receiving device has a plurality of antenna elements, it is possible to obtain the same effects as those of the first to third embodiments. Further, the timing synchronization only needs to take one pattern of the reference signal and the feedback channel estimation needs to be performed for only one branch, so that the configuration of the entire receiving apparatus can be simplified.

  It should be noted that the present invention is not limited to the type, arrangement, number and the like of the members described above in the above-mentioned embodiment, and the constituent elements thereof are appropriately replaced with those having the same operational effect, which deviates from the gist of the invention. It can be appropriately changed within the range not to be.

  Specifically, in each of the above embodiments, the case where the information indicating the channel estimation value is included in the feedback information has been described, but the present invention is not limited to this, and the tap coefficient (weighting coefficient, transmission side weight) or the like can be referred to. Other information regarding the signal reception timing may be included in the feedback information.

  Further, although cases have been described with the above embodiments where feedback information is received via the base station 300 or direct transmission / reception of feedback information is performed between a transmission device and a reception device, the present invention has some extent. When the delay is allowed, the feedback information may be notified by a mobile phone or the like, or the memory storing the feedback information may physically move.

  Further, in the present invention, a plurality of antenna elements may be grouped and the same reference signal may be transmitted within the group, or directivity may be controlled for each group to increase the directivity. Further, in the present invention, the antenna elements to be grouped may be changed for each user. Further, in the present invention, the number of antenna elements in the group may be changed according to the moving speed or the like. When the same reference signal is transmitted in the group, the amount of calculation can be reduced, the transmission time of the reference signal can be shortened, and the gain can be improved.

  Further, although cases have been described with the above embodiments where the transmission control information calculation section calculates a phase shift, the phase shift and delay components may be obtained and included in the feedback information. In this case, the directivity control can be performed in consideration of the delay amount.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a transmitter that transmits a signal to a communication partner by MIMO transmission using a plurality of antenna elements and a communication partner of this transmitter, and a receiver that receives the signal transmitted from the transmitter.

100, 400, 500 Transmission device 101 Timing control unit 102 Reference signal generation unit 103, 105 Modulation unit 104 Transmission signal generation unit 106 Phase shifter 107 Phase calculator 108, 123, 606 Addition unit 109 Radio transmission unit 110 Antenna element 121 Tap Coefficient multiplication unit 124 Comparison unit 125 Correction amount calculation unit 200,600 Reception device 201,601 Antenna 202,602 Radio reception unit 203,607 Demodulation unit 204,603 Correlator 205,604 Transmission control information calculation unit 300 Base station 501,605 FIR filter 502 Tap coefficient calculator

Claims (8)

A transmitting device for transmitting a signal to a receiving device of a communication partner by spatial multiplex transmission using a plurality of antenna elements,
Reference signal generators that generate the same number of reference signals as the antenna elements, which are known in the receiving device and have different patterns from each other,
For each of the antenna elements, based on feedback information including information based on the reception timing of each of the reference signals in the past by the receiving device, a phase adjusting unit that adjusts the phase of a transmission signal including data and pilot symbols,
For each of the antenna elements, the phase-adjusted transmission signal, the different reference signals are superimposed, the addition unit that outputs the same number of superimposed signals as the antenna element,
A radio transmitting unit that radio-transmits each of the superimposed signals from a corresponding antenna element,
Equipped with,
The amplitudes of the transmission signals transmitted from the antenna elements are substantially the same, and the amplitude of the reference signal is substantially the same as one of the transmission signals.
Transmitter. The wireless transmission unit omnidirectionally transmits the reference signals from the antenna elements,
The transmission device according to claim 1. The phase adjustment unit,
A phase calculator that calculates a correction amount of the phase for forming directivity based on the feedback information,
For each antenna element, a phase shifter that shifts the phase of the transmission signal based on the correction amount of the phase calculated by the phase calculator,
Has,
The transmitter according to claim 1 or 2. The phase adjustment unit,
A tap coefficient calculator for calculating a tap coefficient for forming directivity based on the feedback information,
An FIR filter that configures a filter with tap coefficients calculated by the tap coefficient calculator for each antenna element, and adjusts the phase of the transmission signal by passing the transmission signal through the filter,
Has,
The transmitter according to claim 1 or 2. A receiving device which is a communication partner of the transmitting device according to claim 1 and which receives a signal transmitted from the transmitting device,
A demodulation unit that demodulates the received signal and extracts the data,
A correlator that performs a correlation calculation for each of the reference signals with respect to the received signal, and detects the reception timing of each of the reference signals,
A transmitter for transmitting feedback information including information based on the reception timing of each of the reference signals to the transmitter,
A receiver comprising the. A transmission control information calculation unit that performs channel estimation based on the reception timing of each of the reference signals, and includes information indicating a channel estimation value as the information based on the reception timing in the feedback information.
The receiving device according to claim 5. A plurality of antenna elements each receiving a signal transmitted from the transmitter,
A line compensator that performs line estimation for each of the antenna elements based on the reception timing of one reference signal detected by the correlator, and uses the line estimation value to compensate for the line fluctuation of the received signal;
An adding unit for adding the received signals in which the line fluctuations are compensated,
Further has
The demodulator demodulates the received signal output from the adder to take out data,
The receiving device according to claim 5. A communication method in which a transmitter having a plurality of antenna elements transmits a signal to a receiver by spatial multiplexing transmission,
The transmitter is
Generating the same number of reference signals as the antenna elements, which patterns are different from each other, which are known in the receiving device,
Adjusting the phase of the transmission signal containing data and pilot symbols for each antenna element,
For each of the antenna elements, the phase-adjusted transmission signal, superimposing the reference signals different from each other, and outputting the same number of superimposed signals as the antenna element,
Wirelessly transmitting each of the superimposed signals from a corresponding antenna element,
Have
The amplitudes of the respective transmission signals transmitted from the respective antenna elements are substantially the same, and the amplitude of the reference signal is substantially the same as one of the transmission signals,
The receiving device,
Receiving a signal transmitted from the transmitter,
Demodulating the received signal and extracting the data,
Performing a correlation operation on each of the reference signals with respect to the received signal, and detecting the reception timing of each of the reference signals,
Transmitting feedback information including information based on the reception timing of each reference signal to the transmission device,
Have
The transmitter is
In the step of adjusting the phase, adjusting the phase of the transmission signal based on the feedback information received from the receiving device,
Communication method.

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