The present disclosure relates to a wireless communication system, a wireless communication method, a wireless communication processing device, and a wireless communication processing program, and more particularly, to a wireless communication system, a wireless communication method, a wireless communication processing device, and a wireless communication processing program suitable for a case of using a relay capable of dynamically controlling a beam direction.
Non Patent Literatures 1 and 2 below disclose a wireless communication system that uses a relay device capable of dynamically controlling a beam direction.
The system illustrated in
The terminal device 14 can establish wireless communication with the base station device 10 directly or via the relay device 12. The terminal device 14 can generate a plurality of beams. Here, it is assumed that the number of terminal beams emitted by the terminal device 14 is Nrx.
According to the wireless communication system illustrated in
By the way, in the above-described conventional wireless communication system, it is necessary to set an appropriate beam direction in the relay device 12 in order to cause the relay device 12 to appropriately relay a signal between the base station device 10 and the terminal device 14. On the other hand, the relay device 12 cannot control the beam direction by itself. For this reason, in the above wireless communication system, it is necessary to search for the direction of the beam for each combination of individual beams and then instruct an optimum beam direction to the relay device 12.
Here, the number of beam searches L required for the system illustrated in
L=(the number of transmission beams Ntx)*(the number of relay beams Nrelay)*(the number of relay devices M)*(the number of terminal beams Nrx)
For this reason, the wireless communication system illustrated in
The present disclosure has been made in view of the above problems, and a first object of the present disclosure is to provide a wireless communication system capable of sufficiently reducing the overhead required for beam selection in a relay device while using the relay device capable of dynamically controlling the beam direction.
Moreover, a second object of the present disclosure is to provide a wireless communication method capable of sufficiently reducing the overhead required for beam selection in a relay device while using the relay device capable of dynamically controlling the beam direction.
Moreover, a third object of the present disclosure is to provide a wireless communication processing device capable of sufficiently reducing the overhead required for beam selection in a relay device while using the relay device capable of dynamically controlling the beam direction.
Furthermore, a fourth object of the present disclosure is to provide a wireless communication processing program for sufficiently reducing the overhead required for beam selection in a relay device while using the relay device capable of dynamically controlling the beam direction.
In order to achieve the above objects, it is preferable that a first aspect is a wireless communication system including a base station device, a relay device, and a terminal device,
Moreover, it is preferable that a second aspect is a wireless communication method for realizing wireless communication that uses a base station device, a relay device, and a terminal device, the wireless communication method including:
Moreover, it is preferable that a third aspect is a wireless communication processing device for realizing wireless communication using a base station device configured to transmit a control signal including a set value, a relay device configured to receive the control signal and dynamically select a phase weight that determines a beam direction of a reflected wave according to the set value, and a terminal device configured to transmit a reference signal having a low frequency and a reference signal having a high frequency,
Moreover, it is preferable that a fourth aspect is a wireless communication processing program for realizing wireless communication using a base station device configured to transmit a control signal including a set value, a relay device configured to receive the control signal and dynamically select a phase weight that determines a beam direction of a reflected wave according to the set value, and a terminal device configured to transmit a reference signal having a low frequency and a reference signal having a high frequency,
According to the first to fourth aspects, it is possible to sufficiently reduce the overhead required for beam selection in a relay device while using the relay device capable of dynamically controlling the beam direction.
In the learning phase, the following processing is executed in order to learn the relationship between a wireless propagation path between the base station device 20 and the terminal device 24, and the phase weight used in the relay device 22.
(1) The base station device 20 transmits a control signal to the relay device 22.
(2) The relay device 22 receives the control signal and sets a phase weight that determines the reflection direction of the beam.
(3) The terminal device 24 outputs a high-frequency millimeter wave signal as a measurement signal. The measurement signal arrives at the base station device 20 via the relay device 22. The base station device 20 detects the communication quality in a high frequency band on the basis of the received measurement signal. Hereinafter, the result of such detection will be referred to as “millimeter wave quality”.
(4) The terminal device 24 further transmits channel state information (CSI) on a low-frequency signal in order to estimate the state of a channel. The CSI includes information indicating the state of a channel constituting a wireless propagation path, such as scattering, decay, and output attenuation. The CSI is received by the base station device 20 as illustrated in the drawing.
(5) The base station device 20 stores three of the “phase weight” set by the relay device 22, the “low-frequency CSI” received from the terminal device 24, and the “millimeter wave quality” received via the relay device 22 as data set, and performs machine learning processing. As a result, what kind of “millimeter wave quality” is obtained by setting what kind of “phase weight” under what kind of “low-frequency CSI” is learned.
(1) The terminal device 24 transmits low-frequency CSI. The low-frequency CSI includes information indicating the latest state of the wireless propagation path and is received by the base station device 20.
(2) In the base station device 20, the state of the channel indicated by the low-frequency CSI is applied to the above learning model, and the phase weight that realizes the optimum communication quality under the current state is estimated.
(3) The base station device 20 transmits a control signal to the relay device 22 in order to transmit the estimated phase weight.
(4) The relay device 22 sets a phase weight designated by the control signal. As a result, the beam of the relay device 22 is directed in a direction in which efficient relay is realized.
(5) Thereafter, transmission signals of high-frequency millimeter waves are exchanged between the base station device 20 and the terminal device 24.
As described above, in a wireless communication system according to the present embodiment, the beam setting of the relay device 22 can be performed remotely from the base station device 20. Moreover, by using a learning model generated in advance, it is possible to easily determine the optimum phase weight without incurring a large search load. Therefore, according to this system, optimum beam setting can be realized without causing excessive search overhead even when the number of transmission beams Ntx, the number of relay beams Nrelay, the number of relay devices M, and the number of terminal beams Nrx are large.
The processing device 25 has a function of collecting, accumulating, and processing information received and demodulated by the base station device 20. The above-described learning of a data set and estimation processing using a learning model are executed in the processing device 25.
Each of the base station device 20 and the terminal device 24 has a function of transmitting and receiving signals in two or more different frequency bands. In the example illustrated in
However, the combination of a CH and a frequency band is not limited thereto, and the CH1 may be used for communication in a low frequency band and the CH2 may be used for communication in a high frequency band. Moreover, frequency bands used for communication are not limited to those exemplified in the present embodiment. Furthermore, the frequency band may be a licensed band or an unlicensed band.
The relay device 22 is disposed to relay a transmission signal from the base station device 20 or the terminal device 24 to the other. By using the relay device 22, it is possible to avoid a shield existing between the base station device 20 and the terminal device 24. Moreover, a spatial multiplexing effect due to an increase in propagation paths can be obtained. The relay device 22 includes a communicator for receiving a control signal. As a result, the relay device 22 can be controlled and managed remotely.
A control signal is transmitted from, for example, the base station device 20. Although
The processing device 25 includes a base station device IF 26. The base station device IF 26 is an interface for receiving information transferred from the base station device 20 and transmitting a notification from the processing device 25 to the base station device 20. The information received by the base station device IF 26 includes the information regarding the millimeter wave quality obtained at the CH1 and the low-frequency CSI obtained at the CH2, that is, the channel information of the wireless propagation path.
The processing device 25 includes a database unit 28. The database unit 28 stores the information transferred from the base station device 20 and the set value of the phase weight provided to the relay device 22 as a data set. Specifically, the processing device 25 stores the information on the millimeter wave quality of the CH1 and the channel information of the CH2 emitted from the terminal device 24 in the database unit 28 in association with the set value in a period from notification of the set value related to the phase weight to the relay device 22 until updating of the set value. When learning of all or a large number of set values that can be adopted by the relay device 22 is completed, the processing device 25 gets into a state of being able to select a set value that maximizes the communication quality of the CH1.
The processing device 25 further includes a learning processing unit 30 and an estimation processing unit 32. The learning processing unit 30 calculates a learning model using a large number of data sets stored in the database unit 28. On the other hand, the estimation processing unit 32 applies the channel information acquired via the base station device IF 26 to the learning model generated by the learning processing unit 30 so as to estimate a set value to be set in the relay device 22 in order to obtain the best millimeter wave quality. The set value may be directly estimated by the estimation processing unit 32 from the channel information. Alternatively, the estimation processing unit 32 may estimate the communication quality of the CH1 corresponding to the provisional set value from the channel information, and select a set value at which the best estimated quality of the CH1 is obtained.
The base station device 20 includes a CH1 transceiver unit 34 and a CH2 transceiver unit 36. The CH1 transceiver unit 34 has a function for performing wireless communication in a high frequency band. On the other hand, the CH2 transceiver unit 36 has a function for performing wireless communication in a low frequency band.
The base station device 20 includes a quality acquisition unit 38 and an information acquisition unit 40. The quality acquisition unit 38 measures an index related to the communication quality of the CH1 on the basis of a measurement signal transmitted on the CH1. Specifically, the received signal strength indicator (RSSI), the reference signal received quality (RSRQ), the reference signal received power (RSRP), the signal-to-interference-plus-noise ratio (SINR), the throughput, the received power, the delay time, and the like are measured. On the other hand, the information acquisition unit 40 acquires the channel information of the CH2 by channel estimation using the low-frequency CSI transmitted on the CH2.
The base station device 20 also includes a processing device IF 42. The processing device IF 42 is an interface for transferring information acquired by the base station device 20 to the processing device 25 and receiving information, notification of which is provided from the processing device 25.
The base station device 20 further includes a control signal generation unit 44. The control signal generation unit 44 has a function of generating a control signal, notification of which is provided to the relay device 22, on the basis of the information, notification of which is provided from the processing device 25. The control signal includes information of a phase weight to be set in the relay device 22.
Specifically,
The relay device 22 also includes a weight setting unit 48 and a reflector unit 50. The weight setting unit 48 determines a phase weight to be provided to the reflector unit 50 on the basis of the set value acquired by the control management communication unit 46. For example, in a case where a reflection angle to be realized by the relay device 22 is designated as the set value, the phase weight is determined such that the millimeter wave signal of the CH1 is reflected at the designated angle.
The reflector unit 50 includes a plurality of reflector elements. Each of the reflector elements reflects a high-frequency radio wave arriving through the CH1 in an intended direction, and thus shifts the phase of the reflected radio wave. Then, the reflector unit 50 can dynamically and arbitrarily control the reflection direction of the radio wave by setting a phase shift amount different for each reflector element as the phase weight.
The terminal device 24 includes a CH1 transceiver unit 52 and a CH2 transceiver unit 54. The CH1 transceiver unit 52 has a function for performing wireless communication in a high frequency band. On the other hand, the CH2 transceiver unit 54 has a function for performing wireless communication in a low frequency band.
The terminal device 24 also includes a CH1 reference signal generation unit 56 and a CH2 reference signal generation unit 58. The CH1 reference signal generation unit 56 generates a reference signal for measuring the radio quality of the CH1, that is, a signal indicated as a “MEASUREMENT SIGNAL (MILLIMETER WAVE)” in
Reference signals generated by the CH1 reference signal generation unit 56 or the CH2 reference signal generation unit 58 are transmitted from the CH1 transceiver unit 52 or the CH2 transceiver unit 54 via a transmission timing control unit 60. The transmission timing control unit 60 has a function of adjusting the transmission timing of the reference signals. Specifically, the transmission timing control unit 60 adjusts the transmission timing of the reference signals in a manner such that the measurement of the CH1 and the CH2 can be executed simultaneously or within a certain time error range.
Upon receiving the transmission trigger, the base station device 20 transmits a control signal to the relay device 22 (step 102). The relay device 22 sets a relay parameter such as a phase weight, a beam weight, or a beam angle on the basis of information included in the control signal (step 104).
The terminal device 24 transmits the reference signal of the CH1 and the reference signal of the CH2 (steps 106 and 108). The reference signals are transmitted simultaneously or within an allowable time error range. The transmission trigger of the reference signal may be provided to the terminal device 24 via the relay device 22, or may be periodically generated by the terminal device 24 itself.
The base station device 20 receives the reference signal of the CH1 and measures the communication quality of the CH1 measured with the signal (step 110). Specifically, the RSSI, the RSRQ, the RSRP, the SINR, the throughput, the received power, the delay time, and the like are measured as described above. Moreover, the base station device 20 receives the reference signal of the CH2, and performs channel estimation regarding the CH2 on the basis of the signal (step 112). Then, the result of the quality measurement of the CH1 and the result of the channel estimation of the CH2 are transferred to the processing device 25 (step 114). Note that processing by calculation processing may be added to the results of the quality measurement and the channel estimation before transfer.
The processing device 25 stores the information transferred from the base station device 20 and the set value provided to the relay device 22 on the control signal in the database unit 28 as one data set (step 116). Thereafter, the processing of steps 106 to 116 described above is repeated for a certain period. The certain period is set to a time at which a predetermined number of data sets are obtained for one set value. During this time, the terminal device 24 may be stationary or moving.
When the certain period elapses, that is, when a predetermined number of data sets are acquired for one set value, a new control signal is provided to the relay device 22, and the set value is updated. By repeating such processing, information on the relationship among the communication quality of the CH1, the channel state of the CH2, and the set value of the relay device is collected.
When information can be collected for a large number or all of set values adoptable in the relay device 22, learning processing is performed (step 118). The learning processing is performed in the processing device 25. By the learning processing in this step, a learning model in which the state of the CH2, the set value of the relay device 22, and the communication quality of the CH1 are associated with each other is obtained.
By the way, in the present embodiment, CSI regarding the CH2 may be acquired from a reference signal of the CH2, and an arrival direction of the reference signal viewed from the base station device 20 may be estimated from the CSI. Then, in a case where the arrival direction of the reference signal is estimated, the learning model may be created using the arrival direction as a main factor representing the state of the CH2.
Upon receiving the reference signal of the CH2, the base station device 20 executes channel estimation of the CH2 using the signal (step 122). Next, the estimated result is transferred to the processing device 25 (step 124).
The processing device 25 applies the result of the channel estimation to the learning model obtained by the learning processing, and estimates the set value to be set in the relay device 22 (step 126). Notification of the result of the estimation processing is provided to the base station device 20 (step 128). Then, the base station device 20 adds the notification information to the control signal and transmits the control signal to the relay device (step 130).
The relay device 22 changes the set value for determining the direction of the beam on the basis of the information added to the control signal (step 132). Thereafter, data is transmitted and received between the base station device 20 and the terminal device 24 (steps 134 and 136).
As described above, according to the wireless communication system of the present embodiment, it is possible to instruct an optimum set value to the relay device 22 without requiring a large search load in the estimation phase by using a learning model learned in the learning phase. Therefore, according to the wireless communication system of the present embodiment, it is possible to sufficiently reduce the overhead required for beam selection in the relay device 22 while using the relay device 22 capable of dynamically controlling the beam direction.
In the first embodiment described above, the learning phase and the estimation phase are performed separately and independently. However, the present disclosure is not limited thereto. For example, in the estimation phase, the reference signal of the CH1 may be transmitted to the terminal device 24 together with the reference signal of the CH2, and the information collection may be performed similarly to the learning phase.
Moreover, the learning phase and the estimation phase are not necessarily performed in series, and may be executed in parallel. If they are executed in parallel, it is possible to estimate the optimum beam setting while updating the learning model in real time.
Moreover, in the first embodiment described above, the intelligent reflector is used as the relay device 22. However, the present disclosure is not limited thereto, and a smart repeater may be used as the relay device 22.
As illustrated in
The relay device 62 includes a base station-side antenna unit 66. The base station-side antenna unit 66 is an antenna unit for communicating with the base station device 20. The base station-side antenna unit 66 can also perform beamforming similarly to the user-side antenna unit.
The relay device 62 further includes an amplification unit 68. The amplification unit 68 has a function of amplifying signal power received by the user-side antenna unit 64 or the base station-side antenna unit 66. The amplification unit 68 may have a function of performing frequency conversion on the reception signals. Moreover, in order to support transmission by time division duplex (TDD), amplifiers corresponding to upper and lower link directions may be provided in the amplification unit 68. In this case, upper and lower link timings may be separately acquired via the control management communication unit 46, and two amplifiers may be switched in accordance with the timing.
According to the relay device 62 having the above-described function, it is possible to dynamically control the direction of the beam on the basis of the control signal provided from the base station device 20 and appropriately relay the radio signal between the base station device 20 and the terminal device 24. Therefore, even if the relay device 22 illustrated in
The terminal device 70 used in the present embodiment includes a terminal positioning unit 72. The terminal positioning unit 72 has a function of estimating the position of the terminal device 70. The position of the terminal device 70 is estimated by, for example, positioning by a global navigation satellite system (GNSS), indoor positioning, self-position estimation, or the like.
The terminal device 70 further includes a terminal information generation unit 74. The terminal information generation unit 74 has a function of generating terminal positional information acquired by the terminal positioning unit 72 as notification information. The terminal positional information may be included in a reference signal of the CH2 for notification, or may be included in a different signal and transmitted using the CH2. In a case where the terminal positional information is included in a signal different from a reference signal, the transmission timing control unit 60 controls the transmission timing so that the signal is transmitted simultaneously with the reference signals of the CH1 and the CH2 or within a certain allowable error time.
The signal including the positional information of the terminal device 70 is received by the base station device 20 together with the reference signal of the CH1 or the CH2. In the present embodiment, the information acquisition unit 40 of the base station device 20 has a function of acquiring terminal positional information from the signal. Then, the terminal positional information is transferred from the base station device 20 to the processing device 25.
In the learning phase, the processing device 25 includes the terminal positional information in the data set and stores the terminal positional information in the database unit 28. Then, the learning processing unit 30 generates a learning model using the terminal positional information as one element. Therefore, it is possible in the present embodiment to obtain a learning model based on the relationship among the state of the CH2, the position of the terminal device 70, the set value of the relay device 22, and the communication quality of the CH1.
In the estimation phase, the processing device 25 first acquires the position of the terminal device 70 in addition to the state of the CH2. Then, in the estimation processing unit 32, the processing device 25 estimates a set value of the relay device 22 that provides the CH1 with the best communication quality under the current position of the CH2 and the current position of the terminal device 70.
As described above, it is possible in the present embodiment to generate a learning model including the position of the terminal device 70. Then, the set value of the relay device 22 can be determined using the learning model in consideration of the position of the terminal device 70. Therefore, according to a wireless communication system of the present embodiment, the setting accuracy of the beam direction can be further enhanced and the communication efficiency can be enhanced as compared with the case of the first embodiment.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2021/045871 | 12/13/2021 | WO |