JP2017069688A - Power transmission device, power reception device and communication method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: 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 multiplexing transmission using a plurality of antenna elements, a receiving device that is a communication partner of the transmitting device and receives a signal transmitted from the transmitting device, and uses these Related to the communication method.

  Conventionally, a technique for improving frequency utilization efficiency by spatially multiplexing data using an array antenna including a plurality of antenna elements is known (for example, Patent Document 1). In particular, in recent years, a technique called Massive MIMO, in which data is spatially multiplexed and transmitted using an array antenna including a large number of antenna elements, has attracted attention. Communication using sub-millimeter waves to millimeter waves that can ensure a wide band can reduce the antenna size and the antenna interval, and thus is compatible with Massive MIMO including a large number of antenna elements. Massive MIMO is one of the important element technologies in the fifth generation wireless communication system (5G).

  In Massive MIMO, spatial multiplexing can be realized and power efficiency can be improved by adjusting the phase of a large number of antenna elements and directing a narrow beam toward a communication partner.

JP-T-2006-504354

  In a device that uses an array antenna to spatially multiplex and transmit data, it is necessary to form a beam by adjusting the phase between antenna elements due to variations in parts or variations in the wiring length between the device body and the antenna. is there. In addition, 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 initially set beam is not optimal, so phase adjustment is adaptively performed. Need to go and form a beam.

  In 5G, which uses a high frequency band that has high linearity and is difficult to emit radio waves, it is necessary to form a narrow beam in order to obtain a predetermined communication distance, so that the beam is formed with high accuracy. This is particularly important.

  However, conventionally, no technology has been disclosed for adaptively and instantaneously following the beam in the optimum direction with high accuracy in response to changes in the environment or movement of the communication partner during massive MIMO transmission.

  The object of the present invention is to adaptively and immediately follow a beam in an optimum direction with high accuracy in response to environmental changes and movement of a communication partner during communication of spatial multiplexing transmission using a multi-antenna such as Massive MIMO. It is an object of the present invention to provide a transmission device and a reception device that can improve efficiency, and a communication method using them.

  The transmitting apparatus according to the present invention is a transmitting apparatus that transmits a signal to a receiving apparatus of a communication counterpart by spatial multiplexing transmission using a plurality of antenna elements, the antennas being known in the receiving apparatus and having different patterns. A reference signal generator for generating the same number of reference signals as elements; and for each antenna element, data and pilot symbols are included based on feedback information including information related to the reception timing of each of the past reference signals by the receiver A phase adjustment unit that adjusts the phase of the transmission signal, and an addition unit that superimposes the reference signals different from each other on the transmission signal whose phase is adjusted for each antenna element, and outputs the same number of superimposed signals as the antenna elements And a wireless transmission unit that wirelessly transmits each superimposed signal from a corresponding antenna element.

The receiving apparatus according to the present invention is a receiving apparatus that is a communication partner of the transmitting apparatus and receives a signal transmitted from the transmitting apparatus, and a demodulator that demodulates the received signal and extracts data, and the receiving A correlator that performs a correlation operation on each reference signal with respect to a signal and detects reception timing of each reference signal; and a transmission unit that transmits feedback information including information related to the reception timing of each reference signal to the transmission device And a receiving device.
Take the configuration.

  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 the patterns are mutually different. Generating the same number of reference signals as the antenna elements, adjusting the phase of the transmission signal including data and pilot symbols for each antenna element, and transmitting the phase adjusted for each antenna element Superposing the reference signals different from each other on a signal, outputting the same number of superposed signals as the antenna elements, and wirelessly transmitting the superposed signals from the corresponding antenna elements, and the receiving apparatus Receiving a signal transmitted from the transmitting device; demodulating the received signal to extract data; Performing a correlation operation on each reference signal with respect to the received signal, detecting a reception timing of each reference signal, and transmitting feedback information including information related to the reception timing of each reference signal to the transmission device The transmitter adjusts the phase of the transmission signal based on the feedback information received from the receiver in the step of adjusting the phase.

  According to the present invention, during spatial multiplexing transmission communication, the beam can be adaptively and instantaneously accurately followed in the optimum direction according to the environmental change and the movement of the communication partner, and the power efficiency can be improved. .

The figure which shows the structure of the communication system which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the transmitter which concerns on Embodiment 1 of this invention. 1 is a block diagram showing a configuration of a phase calculator according to Embodiment 1 of the present invention. The block diagram which shows the structure of the receiver which concerns on Embodiment 1 of this invention. The flowchart which shows operation | movement of the communication system which concerns on Embodiment 1 of this 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. The flowchart which shows operation | movement of the communication system which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the transmitter which concerns on Embodiment 2 of this 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. The block diagram which shows the structure of the transmitter which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the receiver which concerns on Embodiment 4 of this invention.

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

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

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

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

  Base station 300 is a base station of a macro cell, receives feedback information transmitted from receiving apparatus 200, and transfers the received feedback information to transmitting apparatus 100.

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

  The transmission apparatus 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 pieces. Modulation units 105-1 to 105-M, M × N phase shifters 106-1-1 to 106-MN, M phase calculators 107-1 to 107-M, and N Addition units 108-1 to 108-N, N wireless transmission units 109-1 to 109-N, and N antenna elements 110-1 to 110-N. The N antenna elements 110-1 to 110-N constitute an array antenna.

  The timing control unit 101 notifies the reference signal generation unit 102 of the timing for outputting the reference signal, and generates the transmission signal #k (k is an integer satisfying 1 ≦ k ≦ M). Notification to 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 that is known in the receiving apparatus 200 and is different from each other, such as an orthogonal spreading code and a PN pattern. Each reference signal #j is preferably orthogonal to each other.

  Each modulation section 103-j modulates reference signal #j output from reference signal generation section 102 and outputs it to radio transmission section 109-j.

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

  Each modulation section 105-k modulates transmission signal #k output from transmission signal generation section 104-k and outputs the modulated signal to phase shifters 106-k-1 to 106-k-N.

  Each phase shifter 106-k-j outputs the transmission signal #k output from the modulation unit 105-k based on the phase correction amount calculated by the phase calculator 107-k for each antenna element 110-j. Shift phase. The phase shifters 106-1-j to 106-Mj output the transmission signal #k after the phase shift to the adding unit 108-j.

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

  Each adder 108-j adds the transmission signals # 1-j to # M-j output from the phase shifters 106-1-j to 106-Mj 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. Thereby, 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 includes N tap coefficient multipliers 121, N channel estimation value calculators 122, an adder 123, a comparator 124, and a correction amount calculator 125. Yes.

  Each tap coefficient multiplier 121-j multiplies the input random signal by tap coefficient #j and outputs the result to channel estimated value calculator 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.

  Channel estimation value calculation section 122-j uses the random signal output from tap coefficient multiplication section 121-j to calculate a channel estimation value indicating the channel fluctuation of the propagation path in a pseudo manner and outputs it to addition section 123. .

  The adding unit 123 adds the channel estimated values output from the channel estimated value calculating unit 122-j and outputs the addition result to the comparing unit 124.

  The comparison unit 124 compares the channel estimation value output from the addition unit 123 with 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 the LMS (Least Mean Square) algorithm, the RLS (Recursive Least Squares) algorithm, or the like based on the error information output from the comparison unit 124, so as to reduce the phase. Then, the tap coefficient is 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 multiplier 121-j.

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

  The receiving apparatus 200 includes an antenna 201, a radio reception unit 202, a demodulation unit 203, N correlators 204, and a transmission control information calculation unit 205.

  Radio receiving section 202 performs radio processing such as amplification and down-conversion on the received signal received by antenna 201 and outputs the result to demodulation section 203 and correlators 204-1 to 204-N.

  Demodulation section 203 performs channel estimation using pilot symbols included in the reception signal output from radio reception section 202, and compensates for channel fluctuations of data symbols using channel estimation values. Thereafter, the demodulator 203 demodulates the data symbol and extracts the data.

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

  The transmission control information calculation unit 205 detects the reception timing of the reference signals # 1 to #N based on the correlation values output from the correlators 204-1 to 204-N, performs channel estimation based on the reception timing, Feedback information including information indicating the 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 transmission device 100 transmits the reference signals # 1 to #N from the antenna elements 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 a correlation value can be obtained for only one reference signal #j pattern.

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

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

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

  The base station 300 receives data #k from the receiving device 200-k (S7). Thereafter, 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 illustrating an output signal of the correlator 204-k. 6 and 7, pilot symbols # 1 to #M are simply referred to as pilots.

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

  In this case, as illustrated in FIG. 7, the reception device 200-k receives the pilot symbols # 1 to #M during the times t1 'to t2'. However, since the directivity of the transmission signal from transmission apparatus 100 is controlled, reception apparatus 200-k receives pilot symbol #k at a reception level relatively higher than other pilot symbols that cause interference. can do. Similarly, the receiving apparatus 200-k can receive the user data #k between times t3 'and t4' with a relatively high reception level compared to other user data that causes interference. Note that the receiving device 200-k receives the reference signals # 1 to #N during the times t2 'to t3', but discards these signals without using them for the demodulation processing or the like.

  FIG. 8 is a diagram illustrating 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 obtained, the correlation value is extremely higher than the others at the reception timing of the reference signal #j. 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 receives the same number of reference signals as antenna elements 110 that are known to the communication partner and have different patterns, for each antenna element 110 after phase adjustment. The transmission signal and the reference signal are transmitted from each antenna element 110 by being inserted into the transmission signal. Further, transmitting apparatus 100 calculates a phase for forming directivity based on feedback information including information indicating a channel estimation value from a communication partner, and adjusts the phase of the transmission signal. As a result, during spatial multiplexing transmission communication, the beam can be immediately followed in the optimum direction with high accuracy in accordance with the environmental change and the movement of the communication partner, and the power efficiency can be improved.

  In the above description, 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. However, the present embodiment is not limited to this, and as illustrated in FIG. The present invention can also be applied to direct wireless transmission from the receiving apparatus 200 to the transmitting apparatus 100 with no directivity. Further, in the present embodiment, as shown in FIG. 10, a one-to-one entrance line (one-to-one communication in which two communication devices have the functions of the transmission device 100 and the reception device 200, respectively). Can also be applied.

In the above description, the case of calculating the tap coefficient sequentially corrected by the phase calculator 107-k has been described. In the present embodiment, the configuration of the phase calculator 107-k is [tap coefficient matrix] = [line Estimated matrix] A configuration in which a channel estimation value is obtained by the ZF (Zero forcing) method as ⁻¹ , or [tap coefficient matrix] = [line estimation matrix] + [noise matrix] ^{−1 from the} MMSE (Minimum mean square error) method as ⁻¹ A configuration may be used in which a channel estimation value is 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, feedback information can be generated easily and the circuit scale can be reduced.

  In the above description, the case where apparatus 100 transmits a reference signal in all slots has been described. However, in the present embodiment, only when the directivity needs to be updated, the slot 100 includes the reference signal and transmits the reference signal. You may do it. FIG. 11 is a flowchart in this case. In FIG. 11, the step of S11 is inserted between the steps of S4 and S5 in the flow of FIG. 5, the step of S12 is inserted between the steps of S7 and S8, and S13, Step S14 is inserted.

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

  After S7, the receiving device 200-k determines whether or not the directivity needs to be changed based on the reception quality (S12). If the reception quality is good and directivity update is not required (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, apparatus 100 transmits reference signals # 1 to #N again (S14). Thereafter, the flow returns to S3.

  In addition, in FIG. 11, although the case where the receiving apparatus 200-k performs determination of whether the directivity update is necessary and transmission of the directivity control request has been described, in this embodiment, the directivity of the directivity control request is transmitted. The transmission apparatus 100 may determine whether or not an update is necessary.

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

<Configuration of transmitter>
The configuration of transmitting apparatus 400 according to the present embodiment will be described in detail below with reference to FIG. In FIG. 12, parts having the same configuration as in FIG.

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

  Each modulation section 103-j modulates the reference signal #j output from the reference signal generation section 102 and outputs it to each addition section 108-j.

  Each adding unit 108-j adds the transmission signals # 1-j to # M-j output from the phase shifters 106-1-j to 106-Mj for each antenna element 110-j, and The reference signal #j output from the modulation unit 103-j is superimposed, and the superimposed signal #j is output to the wireless transmission unit 109-j. At this time, the amplitude (transmission power) of each of the transmission signals # 1-j to # M-j is substantially the same, and the amplitude of the reference signal #j is one of the transmission signals # 1-j to # M-j. Almost identical.

  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 the signal from the antenna element 110-j. Thereby, 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 the present embodiment. FIG. 14 is a diagram showing a slot format of a received signal according to the present embodiment. In FIGS. 13 and 14, pilot symbols # 1 to #M are simply referred to as pilots.

  As illustrated in FIG. 13, the transmission apparatus 400 multiplex-transmits pilot symbols # 1 to #M from time t11 to time t13 from each antenna element 110-j for each slot, and time t13 to time t15. User data # 1 to #M are multiplexed and transmitted. At this time, transmitting apparatus 100 controls the directivity so that pilot symbol #k and user data #k are received at receiving apparatus 200-k at the maximum reception level. Further, in the present embodiment, transmitting apparatus 400 refers to pilot symbols # 1 to #M or user data # 1 to #M from time t12 to t14 from each antenna element 110-j for each slot. The signal #j is superimposed and transmitted omnidirectionally. At this time, in the transmission antenna #j, the amplitude of each transmission signal #j is substantially the same, and the amplitude of the reference signal #j is substantially 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 transmission apparatus 100 is controlled, reception apparatus 200-k receives pilot symbol #k at a relatively higher reception level than other pilot symbols that cause interference. can do. Similarly, the receiving apparatus 200-k can receive the user data #k between times t13 'and t15' at a relatively large reception level compared to other user data that causes interference.

By directional transmission, amplitude N times the desired destination (receiving apparatus 200-k), while the power is ^doubled N, for other destination phases of each element Since it is random, the power is N times, so 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 the times t12 and t14. The reference signals # 1 to #N act as interference during demodulation, but have almost no effect because they are omnidirectionally transmitted with low transmission power.

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

  FIG. 15 is a diagram illustrating 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 obtained, the correlation value is a very high value compared to the others at the reception timing of the reference signal #j, as in FIG. It 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 that are known to the communication partner and have different patterns to each antenna element 110 after phase adjustment. Superimposed on the transmission signal, the superimposed signal is transmitted from each antenna element 110. Further, transmitting apparatus 400 calculates a phase for forming directivity based on feedback information including information indicating a channel estimation value from the communication partner, and adjusts the phase of the transmission signal. As a result, during the MIMO transmission, the beam can be immediately followed in the optimum direction with high accuracy in accordance with the environmental change and the movement of the communication partner, thereby improving the power efficiency.

  In this embodiment, reference signals # 1 to #M are transmitted by superimposing reference signals # 1 to #M on pilot symbols # 1 to #M and user data # 1 to #M. Dedicated resources (time) can be eliminated, and the transmission efficiency of user data # 1 to #M can be improved.

  Further, in the present embodiment, the transmission period of reference signals # 1 to #M can be lengthened so as to overlap over the entire slot. The longer the transmission period of the reference signals # 1 to #M, the more accurately the channel estimation can be performed.

  In the present embodiment, pilot symbols # 1 to #M are fixed patterns, and reference signals # 1 to #N are set to be orthogonal to pilot symbols # 1 to #M, so that pilot symbols can be used during correlation processing. Therefore, the channel estimation value for each antenna element 110-j can be obtained with higher accuracy.

  In the above description, the case where apparatus 400 transmits a reference signal in all slots has been described. In the present embodiment, only when the directivity needs to be updated, the slot 400 includes the reference signal and transmits the reference signal. You may make it (refer FIG. 11).

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

<Configuration of transmitter>
The configuration of transmitting apparatus 500 according to the present embodiment will be described in detail below with reference to FIG. In FIG. 16, parts having the same configuration as in FIG.

  The transmission apparatus 500 illustrated in FIG. 16 is different from the transmission apparatus 100 illustrated in FIG. 2 in that FIR filters 501-1-1 to 501-M are used 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 modulation section 105-k modulates transmission signal #k output from transmission signal generation section 104-k and outputs the modulated signal to 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 modulation unit 105-k. By passing the filter, the phase of the transmission signal #k is adjusted. The FIR filters 501-1-j to 501-Mj output the transmission signal #k after the phase shift to the adding unit 108-j.

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

  As described above, according to the present embodiment, the same effect as in the first embodiment can be obtained.

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

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

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

  In the present embodiment, the configuration of the communication system is the same as that of FIG. 1 described in the first embodiment, and a description thereof will be omitted. Further, in the present embodiment, the configuration of the transmission apparatus is the same as that of FIG. 2 described in Embodiment 1, and therefore the description thereof is omitted. In this embodiment, the operation of the communication system has the same configuration as that shown in FIGS. 5 and 11 described in Embodiment 1, and thus the description thereof is omitted.

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

  The receiving apparatus 600 includes L antennas 601-1 to 601-L, L radio receiving units 602-1 to 602-L, and L + N-1 correlators 603-1-1 to 603-1. N, 603-2 to 603 -L, a transmission control information calculator 604, L FIR filters 605-1 to 605 -L, an adder 606, and a demodulator 607.

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

  Correlators 603-1-1 to 603-1 -N calculate correlation values by performing a correlation operation between the received signal output from radio reception section 602-1 and known patterns of reference signals # 1 to #M. The calculated correlation value is output to the transmission control information calculation unit 604. Correlator 603-1-1 outputs the calculated correlation value to FIR filter 605-1.

  Correlator 603-i (in this case, i is other than 1) performs a correlation operation between the received signal and the known pattern of reference signal # 1, calculates a correlation value, and outputs the calculated correlation value to 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 values output from the correlators 603-1-1 to 603-1-N, and determines the line based on the reception timing. Estimation is performed, and feedback information including information indicating the channel estimation value is generated and transmitted to the base station 300.

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

  The adder 606 adds the received signals after filtering output from the FIR filters 605-1 to 605-L, performs maximum ratio combining, and outputs the result to the demodulator 607.

  Demodulation section 607 performs channel estimation using pilot symbols included in the added received signal output from addition section 606, and compensates for channel fluctuations in data symbols using channel estimation values. Thereafter, the demodulator 607 demodulates the data symbol and extracts the data.

  Thus, according to the present embodiment, when the receiving apparatus has a plurality of antenna elements, the same effects as in the first to third embodiments can be obtained. In addition, timing synchronization need only be taken for one pattern of the reference signal, and feedback channel estimation need only be performed for one branch, so that the configuration of the entire receiving apparatus can be simplified.

  The present invention is not limited to the above-described embodiments in terms of the type, arrangement, number, etc. of the members, and departs from the gist of the invention, such as appropriately replacing the constituent elements with those having the same operational effects. It can change suitably in the range which does not.

  Specifically, although cases have been described with the above embodiments where information indicating channel estimation values is included in feedback information, the present invention is not limited to this, and reference is made to tap coefficients (weight coefficients, transmission side weights), etc. 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 where feedback information is directly transmitted and received between the transmission device and the reception device, the present invention provides some If this delay is allowed, feedback information may be notified by a mobile phone or the like, or may be physically moved in a memory storing the feedback information.

  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 control may be performed for each group to increase directivity. In the present invention, the antenna elements to be grouped may be changed for each user. Furthermore, 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 within the group, the amount of calculation can be reduced, the reference signal transmission time can be shortened, and the gain can be improved.

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

  The present invention is suitable for a transmitting apparatus that transmits a signal to a communication partner by MIMO transmission using a plurality of antenna elements, and a receiving apparatus that receives a signal transmitted from the transmitting apparatus.

100, 400, 500 Transmitting apparatus 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 Wireless transmission unit 110 Antenna element 121 Tap Coefficient multiplier 124 Comparator 125 Correction amount calculator 200, 600 Receiver 201, 601 Antenna 202, 602 Radio receiver 203, 607 Demodulator 204, 603 Correlator 205, 604 Transmission control information calculator 300 Base station 501, 605 FIR filter 502 Tap coefficient calculator

Claims (9)

A transmitting device that transmits a signal to a receiving device of a communication partner by spatial multiplexing transmission using a plurality of antenna elements,
A reference signal generation unit that generates the same number of reference signals as the antenna elements, which are known in the receiving apparatus and have different patterns,
A phase adjustment unit that adjusts the phase of a transmission signal including data and pilot symbols based on feedback information including information on the reception timing of each reference signal in the past by the reception device for each antenna element;
For each antenna element, an adder that superimposes the reference signals different from each other on the transmission signal whose phase has been adjusted, and outputs the same number of superimposed signals as the antenna elements;
A wireless transmission unit that wirelessly transmits each superimposed signal from a corresponding antenna element;
A transmission apparatus comprising: The wireless transmission unit omnidirectionally transmits the reference signals from the antenna elements.
The transmission device according to claim 1. The amplitude of each transmission signal transmitted from each antenna element is substantially the same, and the amplitude of the reference signal is substantially the same as one of the transmission signals.
The transmission apparatus according to claim 1 or 2. The phase adjusting unit is
A phase calculator that calculates a phase correction amount for forming directivity based on the feedback information;
A phase shifter that shifts the phase of the transmission signal based on the phase correction amount calculated by the phase calculator for each antenna element;
Having
The transmission device according to any one of claims 1 to 3. The phase adjusting unit is
A tap coefficient calculator for calculating a tap coefficient for forming directivity based on the feedback information;
For each antenna element, configure a filter with the tap coefficient calculated by the tap coefficient calculator, and adjust the phase of the transmission signal by passing the transmission signal through the filter; and
Having
The transmission device according to any one of claims 1 to 3. A receiving device that is a communication partner of the transmitting device according to claim 1 and that receives a signal transmitted from the transmitting device,
A demodulator that demodulates the received signal and extracts data;
A correlator for performing a correlation operation on each received signal with respect to each received signal and detecting a reception timing of each referenced signal;
A transmission unit that transmits feedback information including information related to the reception timing of each reference signal to the transmission device;
A receiving apparatus comprising: Further comprising a transmission control information calculation unit that performs channel estimation based on the reception timing of each reference signal, and includes information indicating a channel estimation value in the feedback information as information regarding the reception timing;
The receiving device according to claim 6. A plurality of antenna elements each receiving a signal transmitted from the transmitter;
A channel compensator that performs channel estimation for each antenna element based on reception timing of one reference signal detected by the correlator, and compensates for channel variation of the received signal using a channel estimation value;
An adder for adding the received signal compensated for the line fluctuation;
Further comprising
The demodulator demodulates the received signal output from the adder to extract data,
The receiving device according to claim 6. A transmission method in which a transmission device having a plurality of antenna elements transmits a signal to a reception device by spatial multiplexing transmission,
The transmitter is
Generating the same number of reference signals as the antenna elements that are known in the receiving apparatus and have different patterns from each other;
Adjusting the phase of a transmission signal including data and pilot symbols for each antenna element;
Superposing the reference signals different from each other on the transmission signal whose phase is adjusted for each antenna element, and outputting the same number of superimposed signals as the antenna elements;
Wirelessly transmitting each superimposed signal from a corresponding antenna element;
Have
The receiving device is:
Receiving a signal transmitted from the transmitter;
Demodulating the received signal to retrieve data;
Performing a correlation operation on each of the reference signals with respect to the received signal, and detecting a reception timing of each of the reference signals;
Sending feedback information including information related to the reception timing of each reference signal to the transmission device;
Have
The transmitter is
Adjusting the phase of the transmission signal based on feedback information received from the receiving device in the step of adjusting the phase;
Communication method.

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