COMMUNICATION SYSTEM, COMMUNICATION METHOD, AND CONTROL DEVICE

Abstract

To make it unnecessary to provide a channel estimation processing for a phase shift design in a reflection board and a cooperation control between operators when sharing the reflection board by a plurality of radio communication operators.SOLUTION: A communication system comprises: a base station that communication with at least one terminal by using an electric wave in radio; and a plurality of reflection elements, and comprises: a reflection board that switches a plurality of phase shift patterns of which a propagation characteristic of the electric wave is different from each other by adjusting a phase shift amount in regard to a reflection of the electric wave in each reflection element; and a control apparatus that controls an allocation of a radio resource in regard to a radio communication between the base station and each terminal. The reflection board switches the phase shift pattern in each of a plurality of time slots constructing one period. The control apparatus stores radio link information to which the base station which can perform a radio communication by using the electric wave via the reflection board in each of the plurality of time slots and the terminal are corresponded, and determines the allocation of the radio resource in each time slot on the basis of the radio link information.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a communication system, a communication method, and a control device. [Background technology]

[0002] In order to cover areas where radio waves from a base station (e.g., Base Station (BS)) do not reach directly, the use of a reflector with multiple reflective elements arranged in an array (e.g., Intelligent Reflection Surface (IRS)) is being considered. The reflector reflects radio waves received from the base station toward areas where the radio waves cannot reach directly, for example, by adjusting the phase shift (reflection coefficient) of each reflective element. The use of a reflector makes it possible to control the propagation characteristics to be favorable, so that the transmission power and frequency bandwidth required to achieve the same throughput can be reduced. In addition, since a power amplifier is not required, the reflector can be operated with low energy and low cost. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] D. Mishra and H. Johansson, "Channel estimation and low-complexity beamforming design for passive intelligent surface assisted MISO wireless energy transfer," IEEE ICASSP 2019, 2019, pp.4659-4663. DOI: 10.1109 / ICASSP.2019.8683663 [Non-Patent Document 2] T. Haustein, J. McMenamy, L. Thiele and PSH Leather, "Reconfigurable Intelligent Surface Deployment in 5G and Beyond 5G Cellular Networks," 2022 IEEE 23rd Int. Workshop on Signal Process. Advances in Wireless Commun. (SPAWC), Oulu, Finland, 2022, pp.1-5. Summary of the Invention [Problem to be solved by the invention]

[0004] In order to design the phase shift of each reflecting element of the IRS, it is necessary to perform channel estimation processing for all elements. Non-Patent Document 1 proposes, as the most basic channel estimation method, a method in which a channel for a reflecting element is estimated in a situation where only one reflecting element reflects, and this estimation is repeated for all reflecting elements. However, when this method is used, the number of reflecting elements increases, and the overhead of the channel estimation processing also increases.

[0005] In addition, Non-Patent Document 2 mentions the possibility that the broadband characteristics of the IRS may affect the radio waves of different wireless communication carriers, and indicates the need to control the IRS among multiple wireless communication carriers. However, controlling the IRS among multiple wireless communication carriers requires the installation of a control device for controlling the multiple carriers and the sharing of information among the carriers, which increases infrastructure costs and control costs.

[0006] An object of the present disclosure is to provide a channel estimation process for designing a phase shift in a reflector, and a technology that eliminates the need for cooperative control between multiple wireless communication carriers when the carriers share a reflector. [Means for solving the problem]

[0007] A communication system according to one embodiment of the present disclosure includes a base station that performs wireless communication with at least one terminal using radio waves, a reflector that has a plurality of reflective elements and switches between a plurality of phase shift patterns having different propagation characteristics of the radio waves by adjusting a phase shift amount related to the reflection of the radio waves at each reflective element, and a control device that controls allocation of wireless resources related to wireless communication between the base station and each of the terminals, wherein the reflector switches the phase shift pattern for each of a plurality of time slots that constitute one period, and the control device stores wireless link information that corresponds the base station and the terminal that are capable of wireless communication using the radio waves that pass through the reflector for each of the plurality of time slots, and determines the allocation of the wireless resources in each of the time slots based on the wireless link information.

[0008] In a communication method according to one embodiment of the present disclosure, a base station transmits radio waves related to wireless communication, the reflector includes a plurality of reflecting elements, and switches between a plurality of phase shift patterns having different propagation characteristics of the radio waves by adjusting a phase shift amount related to reflection of the radio waves at each reflecting element, the reflector switches the phase shift pattern for each of a plurality of time slots constituting one period, at least one terminal is capable of receiving the radio waves transmitted from the base station and reflected by the reflector, and a control device stores radio link information that corresponds the base station and the terminal capable of wireless communication using the radio waves passing through the reflector for each of the plurality of time slots, and determines an allocation of radio resources related to wireless communication between the base station and each of the terminals in each of the time slots based on the radio link information.

[0009] A control device according to one embodiment of the present disclosure is a control device that controls allocation of radio resources related to wireless communication between a base station and each of the terminals in a communication system in which a base station transmits radio waves related to wireless communication, the control device has a plurality of reflective elements, and the reflector switches between a plurality of phase shift patterns having different propagation characteristics of the radio waves by adjusting the phase shift amount related to the reflection of the radio waves at each reflective element, the phase shift pattern being switched for each of a plurality of time slots that constitute one period, and at least one terminal is capable of receiving the radio waves transmitted from the base station and reflected by the reflector.The control device stores radio link information that associates the base station and the terminal that are capable of wireless communication using the radio waves that pass through the reflector for each of the plurality of time slots, and determines the allocation of the radio resources in each of the time slots based on the radio link information.

[0010] Furthermore, these comprehensive or specific aspects may be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0011] According to the present disclosure, no channel estimation process is required for designing the phase shift in the reflector. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a configuration example of a communication system according to a first embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of an initial phase shift schedule according to the first embodiment; [Diagram 3] 1 is a sequence chart showing an example of an operation of the communication system according to the first embodiment; [Figure 4] FIG. 1 is a diagram showing an example of a configuration of a wireless link table according to the first embodiment; [Diagram 5] FIG. 13 is a diagram showing a modification of the wireless link table according to the first embodiment. [Figure 6]FIG. 13 is a diagram showing a configuration example of a communication system according to a modified example of method A. [Figure 7] FIG. 13 is a diagram showing a configuration example of a communication system according to a modified example of method B. [Figure 8] FIG. 13 is a diagram showing a configuration example of a communication system according to a modified example of method C. [Figure 9] FIG. 13 is a diagram showing a configuration example of a communication system according to a second embodiment; [Figure 10] FIG. 13 is a diagram showing an example of a phase shift schedule before and after change according to the second embodiment; [Figure 11] 11 is a sequence chart showing an example of an operation of a communication system when a changed phase shift schedule according to the second embodiment is used. [Figure 12] FIG. 13 is a diagram showing an example of the configuration of a wireless link table according to the second embodiment; [Figure 13] FIG. 11 is a diagram for explaining a method for changing a phase shift schedule by a reflector according to the second embodiment; [Figure 14] FIG. 13 is a diagram showing a configuration example of a communication system according to a third embodiment; [Figure 15] A flowchart showing an example of a process for performing terminal positioning using a fingerprint DB using a quantum computer according to a third embodiment. [Figure 16] FIG. 13 shows a SWAP test circuit according to a third embodiment. [Figure 17] A diagram to explain that the fingerprint DB and measured RSS data cannot be directly compared. [Figure 18] FIG. 13 is a diagram for explaining a positioning method 1 according to a third embodiment. [Figure 19] FIG. 13 is a diagram for explaining a positioning method 2 according to a third embodiment. [Figure 20] FIG. 13 is a diagram for explaining a positioning method 3 according to a third embodiment. [Figure 21] FIG. 13 is a diagram for explaining a positioning method 4 according to a third embodiment. [Figure 22] 11 is a flowchart showing an example of a process performed by a control device according to a third embodiment. [Figure 23] Graph comparing positioning errors of positioning methods 1 to 4 according to embodiment 3. [Figure 24] FIG. 1 is a diagram showing a hardware configuration of a computer according to the present disclosure. [Diagram 25] Diagram to explain the overview of cell search in the 5G standard [Figure 26] A diagram to explain the issues when a terminal receives SSB via a reflector. [Figure 27] FIG. 13 is a diagram for explaining a method for implementing a cell search via a reflector according to a fourth embodiment. [Figure 28] FIG. 13 is a diagram showing an example of an operation sequence between a base station, a reflector, and a terminal according to a fourth embodiment. [Figure 29] FIG. 13 is a diagram for explaining a design example of a phase shift pattern switching schedule of a reflector in the case of 120 kHz SCS according to the fourth embodiment. [Diagram 30] FIG. 13 is a diagram for explaining a first design example of a phase shift pattern switching schedule of a reflector in the case of 15 kHz SCS according to the fourth embodiment; [Diagram 31] FIG. 13 is a diagram for explaining a first design example of a phase shift pattern switching schedule of a reflector in the case of 30 kHz SCS according to the fourth embodiment; [Diagram 32] FIG. 13 is a diagram for explaining a second design example of a phase shift pattern switching schedule of a reflector in the case of 30 kHz SCS according to the fourth embodiment; [Diagram 33] FIG. 13 is a diagram for explaining a design example of a phase shift pattern switching schedule of a reflector in the case of 240 kHz SCS according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters and duplicated description of substantially the same configuration may be omitted. This is to avoid the following description becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0014] (Embodiment 1) <System configuration> FIG. 1 is a diagram showing an example of a configuration of a communication system 1 according to the first embodiment.

[0015] As shown in FIG. 1, the communication system 1 includes a control device 5, a base station 10, a reflector 15, and terminals 20 (20A, 20B, 20C, 20D). The communication system 1 may include any number of control devices 5, base stations 10, reflectors 15, and terminals 20. The base station 10 may be read as a Base Station (BS). The reflector 15 may be read as an Intelligent Reflection Surface (IRS), a Reconfigurable Intelligent Surface (RIS), or a Standalone (SA)-IRS. The terminal 20 may be read as a User Equipment (UE).

[0016] The base station 10 transmits radio waves (radio signals) for wireless communication. The base station 10 also receives radio waves (radio signals) transmitted from each terminal 20. The communication method of the radio signals may comply with the standards of mobile communication systems such as 4G, 5G, and 6G.

[0017] The terminal 20 receives radio waves (wireless signals) transmitted from the base station 10. In addition, the terminal 20 transmits radio waves (wireless signals) to the base station 10.

[0018] The control device 5 schedules allocation of radio resources related to wireless communication between the base station 10 and the terminal 20. The radio resources include time resources and frequency resources. In this embodiment, for ease of understanding, the control device 5 is described as controlling one base station 10, but the control device 5 may control multiple base stations 10. In this disclosure, the processes or functions described mainly by the control device 5 may be processes or functions performed by the processor 1001 (FIG. 24) shown in FIG. 24.

[0019] The reflector 15 is a device in which a plurality of passive reflecting elements are arranged in an array. The reflector 15 can adjust the phase shift amount (reflection coefficient) of each reflecting element. For example, as shown in FIG. 1, there are cases where the base station 10 and each terminal 20A, 20B, 20C, and 20D cannot directly perform wireless communication due to the presence of an obstacle 2. In such a case, as shown in FIG. 1, the reflector 15 is installed at an appropriate location and the reflector 15 appropriately adjusts the phase shift amount, so that even if the obstacle 2 exists, the radio waves transmitted from the base station 10 are reflected by the reflector 15 in the direction of the terminals 20A, 20B, 20C, and 20D, and can reach the terminals 20A, 20B, 20C, and 20D. Similarly, the radio waves transmitted from the terminals 20A, 20B, 20C, and 20D are reflected by the reflector 15 in the direction of the base station 10, and can reach the base station 10.

[0020] The reflector 15 may be a device that operates autonomously without being controlled by the base station 10 and / or the control device 5. The reflector 15 that operates autonomously in this manner may be read as an SA-IRS or an autonomous IRS.

[0021] The reflector 15 changes the amount of phase shift of each reflecting element for each predetermined period (time slot). The reflector 15 configures one period with a predetermined number of time slots. In this embodiment, for ease of explanation, it is assumed that one period is configured with five time slots. However, the number of time slots that configure one period may be any number.

[0022] In this embodiment, the first time slot in one period is expressed as t=1, the second time slot as t=2, the third time slot as t=3, the fourth time slot as t=4, and the fifth time slot as t=5.

[0023] The reflector 15 has a plurality of phase shift patterns in which the sets of horizontal phase shift amounts and vertical phase shift amounts are different from each other (i.e., the propagation characteristics of the reflected radio waves are different from each other). In this embodiment, the reflector 15 is described as having five different phase shift patterns s=1, 2, 3, 4, 5 set thereon. However, the number of phase shift patterns set on the reflector 15 may be any number. Also, in this embodiment, for ease of understanding, each phase shift pattern is described as having a different horizontal phase shift amount.

[0024] The reflector 15 switches the phase shift pattern for each time slot according to the phase shift schedule.

[0025] 2 shows an example of an initial phase shift schedule according to Embodiment 1. Next, the phase shift schedule will be described with reference to FIG.

[0026] The phase shift schedule associates a time slot t with a phase shift pattern s. For example, the reflector 15 operating based on the phase shift schedule shown in Fig. 2 sets a phase shift pattern s=1 at time slot t=1, a phase shift pattern s=2 at time slot t=2, a phase shift pattern s=3 at time slot t=3, a phase shift pattern s=4 at time slot t=4, and a phase shift pattern s=5 at time slot t=5 in one period.

[0027] The control device 5, the reflector 15, the base station 10, and the terminal 20 included in the communication system 1 have their time accurately synchronized by Global Navigation Satellite Systems (GNSS) or the like. This allows the switching timing of the time slots to be synchronized among the control device 5, the reflector 15, the base station 10, and the terminal 20.

[0028] <Communication system operation> FIG. 3 is a sequence chart showing an example of the operation of the communication system 1 according to the first embodiment.

[0029] First, the operation in the first period will be described.

[0030] (S101) The base station 10 transmits a pilot signal in time slot t=1.

[0031] (S102) Reflector 15 sets phase shift pattern s=1 in time slot t=1, and reflects the pilot signal of step S101.

[0032] (S103) When the terminal 20A receives the reflected pilot signal in step S102, the terminal 20A transmits communication quality information for the pilot signal to the base station 10 (control device 5). The communication quality information includes Received Signal Strength (RSS) indicating the reception strength of the pilot signal at the terminal 20A. Note that a Received Signal Strength Indicator (RSSI) may be used instead of the RSS. Note that the RSS or RSSI is an example, and an index other than the RSS or RSSI may be used as long as it indicates the reception strength or communication quality.

[0033] (S104) Next, the base station 10 transmits a pilot signal in time slot t=2.

[0034] (S105) The reflector 15 sets the phase shift pattern s=2 in the time slot t=2, and reflects the pilot signal of step S104. If the reflected pilot signal of step S105 is not received by any terminal 20, the base station 10 does not receive the communication quality information corresponding to the time slot t=2.

[0035] (S106) Next, the base station 10 transmits a pilot signal in time slot t=3.

[0036] (S107) Reflector 15 sets phase shift pattern s=3 in time slot t=3 and reflects the pilot signal of step S106.

[0037] (S108) If terminal 20B receives the reflected pilot signal in step S107, terminal 20B transmits communication quality information of the pilot signal to base station 10 (control device 5).

[0038] (S109) Next, the base station 10 transmits a pilot signal in time slot t=4.

[0039] (S110) Reflector 15 sets phase shift pattern s=4 in time slot t=4 and reflects the pilot signal of step S109.

[0040] (S111) If terminal 20C receives the reflected pilot signal in step S110, it transmits communication quality information of the pilot signal to base station 10 (control device 5).

[0041] (S112) Next, the base station 10 transmits a pilot signal in time slot t=5.

[0042] (S113) The reflector 15 sets a phase shift pattern s=5 in time slot t=5, and reflects the pilot signal of step S112. If the reflected pilot signal of step S113 is not received by any terminal 20, the base station 10 does not receive the communication quality information corresponding to time slot t=5.

[0043] Through the above process, the control device 5 is able to receive communication quality information from the terminal 20A in time slot t = 1, and therefore determines that the base station 10 can perform wireless communication with the terminal 20A in time slot t = 1. Similarly, the control device 5 determines that the base station 10 can perform wireless communication with the terminal 20B in time slot t = 3, and determines that the base station 10 can perform wireless communication with the terminal 20C in time slot t = 4.

[0044] In addition, even if the base station 10 can receive communication quality information from a certain terminal 20 in a certain time slot, if the RSS (reception strength) included in the communication quality information is very small (for example, below a predetermined threshold), the control device 5 may determine that the base station 10 cannot perform wireless communication with the terminal 20 in that time slot.

[0045] The control device 5 generates a radio link table based on the transmission of the pilot signal in each time slot and the reception result of the communication quality information. Next, the radio link table will be described.

[0046] FIG. 4 shows an example of the configuration of the wireless link table according to the first embodiment.

[0047] 4, the wireless link table is a table that associates a time slot number t with a link pair between a base station 10 and a terminal 20 that can perform wireless communication during that time slot. Note that the wireless link table may be read as wireless link information.

[0048] Based on the operation in the first cycle described above, the control device 5 creates a wireless link table as shown in FIG. 4, which indicates that at time slot t=1, the base station 10 and the terminal 20A are capable of wireless communication, at time slot t=3, the base station 10 and the terminal 20B are capable of wireless communication, and at time slot t=4, the base station 10 and the terminal 20C are capable of wireless communication, and stores the table in a specified memory 1002 (see FIG. 24).

[0049] The control device 5 refers to the wireless link table and creates the second and subsequent wireless resource allocation schedules for the base station 10 (S120). For example, the base station 10 creates a wireless resource allocation schedule in which wireless communication with the terminal 20A is assigned to the wireless resource corresponding to the time slot t=1, wireless communication with the terminal 20B is assigned to the wireless resource corresponding to the time slot t=3, and wireless communication with the terminal 20C is assigned to the wireless resource corresponding to the time slot t=4.

[0050] Next, returning to FIG. 3, the operation in the second period will be described.

[0051] Based on the radio resource allocation schedule created by the control device 5 in step 120, the base station 10 performs the following operations.

[0052] (S121) The base station 10 transmits a radio signal to the terminal 20A in time slot t=1.

[0053] (S122) The reflector 15 sets a phase shift pattern s=1 in the time slot t=1, and reflects the radio signal of step S121. The terminal 20A receives this reflected radio signal. The terminal 20A may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=1.

[0054] (S123) Base station 10 does not transmit a wireless signal in time slot t=2. This is because phase shift pattern s=2 is set in reflector 15 in time slot t=2, and there is no terminal 20 that can receive a wireless signal reflected by this phase shift pattern s=2.

[0055] (S124) The base station 10 transmits a radio signal to the terminal 20B in time slot t=3.

[0056] (S125) The reflector 15 sets a phase shift pattern s=3 in the time slot t=3, and reflects the radio signal of step S124. The terminal 20B receives this reflected radio signal. The terminal 20B may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=3.

[0057] (S126) The base station 10 transmits a radio signal addressed to the terminal 20C in time slot t=4.

[0058] (S127) The reflector 15 sets a phase shift pattern s=4 in the time slot t=4, and reflects the radio signal of step S126. The terminal 20C receives this reflected radio signal. The terminal 20C may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=4.

[0059] (S128) Base station 10 does not transmit a wireless signal in time slot t=5. This is because phase shift pattern s=5 is set in reflector 15 in time slot t=5, and there is no terminal 20 that can receive a wireless signal reflected by this phase shift pattern s=5.

[0060] The base station 10, the reflector 15, and the terminals 20A, 20B, and 20C may perform the same operations as in the second period described above in the third and subsequent periods.

[0061] According to the above-mentioned process, the control device 5 does not allocate radio resources to a time slot t in which no link pair exists in the radio link table, and therefore the radio resources are used efficiently.

[0062] The control device 5 may periodically (for example, every 10 periods) transmit the pilot signal described in the first period, create the radio link table, and create the radio resource allocation schedule. That is, the control device 5 may periodically initialize the radio resource allocation schedule. This enables the control device 5 to perform control in response to changes in the presence of the terminal 20, such as the entry of a new terminal 20, the exit of an existing terminal 20, and / or the movement of the terminal 20.

[0063] Furthermore, when one base station 10 performs wireless communication with multiple terminals 20 in one time slot, the control device 5 may assign different frequency resources to each terminal 20. For example, when wireless communication with terminals 20B and 20D (see FIG. 1) is possible in time slot t=3, the control device 5 may assign a first frequency resource to terminal 20B and a second frequency resource to terminal 20D when creating a wireless resource allocation schedule.

[0064] FIG. 5 shows a modification of the wireless link table according to the first embodiment.

[0065] When the control device 5 controls multiple base stations 10A, 10B, and 10C, the control device 5 may recognize, for each time slot, with which terminals 20A, 20B, 20C, 20D, and 20E each of the multiple base stations 10A, 10B, and 10C is capable of wireless communication, and create a wireless link table as shown in FIG. 5, in the same manner as described in the first cycle above.

[0066] The wireless link table shown in FIG. 5 associates a time slot number with a link pair between a base station 10 and a terminal 20 that are capable of wireless communication during that time slot.

[0067] 5 indicates that, at time slot t=1, base station 10A can wirelessly communicate with terminal 20B, base station 10B can wirelessly communicate with terminal 20E, and base station 10C can wirelessly communicate with terminal 20D. The same applies to the other time slots.

[0068] The communication system 1 according to the present embodiment may perform wireless communication using a relatively high frequency band (for example, 26 GHz band) such as millimeter waves. That is, the present embodiment may assume a flat channel in which the direct path is dominant.

[0069] Furthermore, in this embodiment, it may be assumed that the movement of the terminal 20 is sufficiently small during the period in which the radio resource allocation schedule is applied.

[0070] In addition, when creating a radio resource allocation schedule, the control device 5 may optimize the allocation of radio resources in consideration of the communication volume required by each terminal 20 so that all communications are completed in as short a time as possible. For example, the control device 5 may calculate the communication volume per subcarrier and per time slot of the radio communication band provided by the base station 10, and determine the allocation of radio resources in each time slot based on the communication volume required by each of the multiple terminals 20 capable of radio communication with the base station 10 so that the communication volume required by the multiple terminals 20 as a whole is satisfied and the number of time slots is minimized. For example, the control device 5 may be communicably connected to a quantum computer, and may optimize the allocation of radio resources using the quantum computer by the method described below. However, the control device 5 may optimize the allocation of radio resources by calculation using a so-called classical computer without using a quantum computer.

[0071] <Optimization of wireless resource allocation using quantum computing> In recent years, methods for efficiently solving complex combinatorial optimization problems using quantum computing have been attracting attention. When solving combinatorial optimization problems using quantum computing, it is necessary to formulate an Ising model equation or a QUBO (Quadratic Unconstrained Binary Optimization) equation according to the problem to be solved. A typical Ising model equation is shown below.

[0072]

number

[0073] Where:

number

[0074] H represents the energy of the field in which all spins exist.

[0075] In the above formula, σ is the bit

number

[0076] In combinatorial optimization using quantum computing, the state of each σ that minimizes H is In other words, the ground state is searched for. Therefore, it is necessary to formulate the problem in such a way that the optimal solution for the target problem is the ground state.

[0077]

number

[0078] In formula 2, x utf is a binary variable that indicates 1 when the number of subcarriers f is assigned to UEu in time slot t. tbvis a binary variable that indicates the difference between the number of available subcarriers F and the total number of actually allocated subcarriers in time slot t and BSb, and v indicates the bit index. D u is the required communication amount [bit] of UEu, S t is the set of UEs included in time slot t in the radio link table, U tb and T denote the set of UEs that can communicate with BSb in time slot t. ut indicates the amount of communication [bit] per subcarrier that UEu can obtain in time slot t. Also, λ1 to λ4 are coefficients greater than 0 that adjust the strength of each term.

[0079] In Equation 2, the first term is a cost term for minimizing the number of required time slots. The second term is a constraint for satisfying the communication volume required by each UE. The third term is a constraint for avoiding resource allocation to UEs not included in the radio link table in each time slot. The fourth term is a constraint for limiting the number of subcarriers assigned to each UE to a maximum of one type in each time slot. The fifth term is a constraint for ensuring that the total number of subcarriers assigned to each UE does not exceed the available range when a single BS can communicate with multiple UEs in each time slot.

[0080] When performing resource allocation using Equation 2, T ut needs to be calculated in advance.

[0081] The channel quality information reported from each UE is the channel estimation value of each BS, the signal power S b , and the noise power N.

[0082] In the case where UEu can communicate with multiple BSs in time slot t, each BS uses the opposite phase of the channel estimate as the precoding coefficient, and the in-phase addition is performed at the receiving point of the UE. ut is expressed as the following Equation 3.

[0083]

number

[0084] Here, B is the bandwidth of one subcarrier [Hz], T is the time of one time slot [sec], B s is the set of BSs that communicate with UEu.

[0085] <Modification> <<Method A>> FIG. 6 shows an example of the configuration of a communication system 1a according to the modified method A.

[0086] In the communication system 1a according to the modified method A shown in Fig. 6, a specific operator A has the right to control the reflector 15, and another operator B does not have the right to control the reflector 15. For example, in Fig. 6, it is assumed that the operator A can control the control device 5A, the reflector 15, and the base station 10A, and the operator B can control the control device 5B and the base station 10B. In this case, the communication system 1a may perform the following operation as method A.

[0087] Operator A uses control device 5A that it manages to control the phase shift pattern of reflector 15 so as to optimize wireless communication between base station 10A and terminals 20A, 20B, and 20C that it manages.

[0088] Operator B performs communication in a state where cascade channel information including the phase shift pattern of reflector 15 is unknown. For example, operator B transmits a wireless signal from base station 10B, which it manages, to terminal 20E, which it manages, using control device 5B, which it manages. If this transmitted wireless signal is reflected when reflector 15 has phase shift pattern s=2, it will reach terminal 20E, which it manages. On the other hand, if this transmitted wireless signal is reflected when reflector 15 does not have phase shift pattern s=2, it will not reach terminal 20E, which it manages.

[0089] <<Method B>> FIG. 7 shows an example of the configuration of a communication system 1b according to the modified technique B.

[0090] In a communication system 1b according to method B of the modified example shown in Fig. 7, a plurality of operators A and B share the control right of the reflector 15. For example, in Fig. 7, it is assumed that operator A can control the control device 5A and the base station 10A, operator B can control the control device 5B and the base station 10B, and operators A and B share the control right of the reflector 15. In this case, communication system 1b may perform the following operation as method B.

[0091] The control right of the reflector 15 is assigned to the operator A and the operator B in a time-division manner. The operator A uses the control device 5A during a first time period assigned to itself to control the phase shift pattern of the reflector 15 so as to be optimal for its base station 10A and terminals 20A, 20B, and 20C, and the operator B performs communication during this first time period in a state in which the cascade channel information including the phase shift pattern of the reflector 15 is unknown. Furthermore, the operator B uses the control device 5B during a second time period (different from the first time period) assigned to itself to control the phase shift pattern of the reflector 15 so as to be optimal for its base station 10B and terminal 20E, and the operator A performs communication during this second time period in a state in which the cascade channel information including the phase shift pattern of the reflector 15 is unknown.

[0092] <<Method C>> FIG. 8 shows an example of the configuration of a communication system 1c according to the modified method C.

[0093] The communication system 1c according to method C has a configuration in which the control device 5 can control each of the base stations 10A, 10B and the reflector 15. The control device 5 optimizes the phase shift of the reflector 15 on the premise that all of the operators A and B communicate simultaneously (all at once). In other words, the control device 5 optimizes the phase shift of the reflector 15 so as to maximize the throughput of each of the operators A and B.

[0094] In the above-mentioned modified methods A, B, and C, the reflector 15 needs to be controlled by the base station 10 and / or the control device 5. In addition, in order to control the phase shift pattern of the reflector 15, a channel estimation process is required for each reflecting element of the reflector 15. Therefore, when the number of reflecting elements is large, the overhead of the channel estimation process for each reflecting element becomes large, and the effective communication speed decreases. By using the SA-IRS, which does not need to be controlled by the base station 10 and / or the control device 5, as the reflector 15, the channel estimation process for each reflecting element becomes unnecessary, and this embodiment can solve such a problem.

[0095] In the method B of the modified example, in order to divide the time during which each operator can control the reflector 15, it is necessary to realize synchronization between the operators and share information on the allocation time. In the method C of the modified example, in addition to the need for a new control device 5 for controlling all the operators, the control device 5 needs to collect information such as channel estimation results from each operator in order to optimize the phase shift of the reflector 15. In this way, control costs and infrastructure costs increase in order to realize cooperation between operators. On the other hand, when the SA-IRS is used as the control device 5, each operator independently performs the radio resource allocation as described in the first embodiment and the communication based on the result, so that each operator can share the reflector 15 without cooperation between the operators.

[0096] (Embodiment 2) 3, in time slots t=2 and t=5, there is no terminal 20 that can communicate even if reflector 15 is used, so control device 5 does not allocate time resources to time slots t=2 and t=5. In embodiment 2, the number of time slots to which time resources are not allocated is reduced as much as possible, thereby improving the utilization efficiency of wireless resources.

[0097] <Communication system configuration> FIG. 9 shows an example of the configuration of a communication system 1 according to the second embodiment.

[0098] The communication system 1 includes a control device 5, a base station 10, a reflector 15, a received power meter 16 provided on the reflector 15, and terminals 20 (20A, 20B, 20C).

[0099] <Phase shift schedule> FIG. 10 shows an example of a phase shift schedule before and after the change according to the second embodiment.

[0100] As shown in FIG. 10, the phase shift schedule associates a time slot number with a phase shift pattern for that time slot.

[0101] The reflector 15 measures the received power for each time slot t using the received power meter 16, and identifies a phase shift pattern s that is not used often. For example, in the operation of the sequence chart shown in Fig. 3, the reflector 15 determines that the phase shift pattern s=2 in the time slot t=2 and the phase shift pattern s=5 in the time slot t=5 are not used.

[0102] Therefore, the reflector 15 deletes the unused phase shift patterns s=2, 5 from the phase shift schedule before the change, and changes the phase shift schedule using only the used phase shift patterns s=1, 3, 4. For example, the reflector 15 assigns phase shift patterns s=1, 3, 4, 1, 3 to time slots t=1, 2, 3, 4, 5, respectively, to generate a changed phase shift schedule. The reflector 15 changes the phase shift schedule so that all used phase shift patterns are assigned to all time slots included in one period.

[0103] That is, the reflector 15 calculates the frequency of wireless communication by the base station 10 for each phase shift pattern based on the received power measured by the received power meter 16, and changes the phase shift pattern of each time slot in one period so that only phase shift patterns (e.g., any of the above phase shift patterns s=1, 3, and 4) whose frequency of wireless communication is equal to or higher than a threshold are included. The reflector 15 may change the phase shift patterns (e.g., the above phase shift patterns s=2 and 5) whose frequency of wireless communication is less than a predetermined threshold among the timeslots so that only phase shift patterns whose frequency of wireless communication is equal to or higher than a threshold are included, or may change the phase shift patterns of all the timeslots so that only phase shift patterns whose frequency of wireless communication is equal to or higher than a threshold are included. That is, the phase shift patterns may be assigned to each timeslot in any order as long as they are phase shift patterns whose frequency of wireless communication is equal to or higher than a threshold.

[0104] FIG. 11 is a sequence chart showing an example of the operation of the communication system 1 in the case where the changed phase shift schedule according to the second embodiment is used.

[0105] (S200) The reflector 15 changes the phase shift schedule by the method described above.

[0106] First, the operation in the first period after the phase shift schedule is changed will be described.

[0107] (S201) The base station 10 transmits a pilot signal in time slot t=1.

[0108] (S202) Reflector 15 sets phase shift pattern s=1 in time slot t=1, and reflects the pilot signal of step S201.

[0109] (S203) If terminal 20A receives the reflected pilot signal in step S202, terminal 20A transmits communication quality information of the pilot signal to base station 10 (control device 5). The communication quality information includes at least the RSS.

[0110] (S204) Next, the base station 10 transmits a pilot signal in time slot t=2.

[0111] (S205) Reflector 15 sets phase shift pattern s=3 in time slot t=2 and reflects the pilot signal of step S204.

[0112] (S206) If terminal 20B receives the reflected pilot signal in step S205, terminal 20B transmits communication quality information of the pilot signal to base station 10 (control device 5).

[0113] (S207) Next, the base station 10 transmits a pilot signal in time slot t=3.

[0114] (S208) Reflector 15 sets phase shift pattern s=4 in time slot t=3 and reflects the pilot signal of step S207.

[0115] (S209) If terminal 20C receives the reflected pilot signal in step S208, it transmits communication quality information of the pilot signal to base station 10 (control device 5).

[0116] (S210) Next, the base station 10 transmits a pilot signal in time slot t=4.

[0117] (S211) Reflector 15 sets the phase shift pattern s=1 in time slot t=4, and reflects the pilot signal of step S210.

[0118] (S212) If terminal 20A receives the reflected pilot signal in step S211, terminal 20A transmits communication quality information of the pilot signal to base station 10 (control device 5).

[0119] (S213) Next, the base station 10 transmits a pilot signal in time slot t=5.

[0120] (S214) Reflector 15 sets phase shift pattern s=3 in time slot t=5 and reflects the pilot signal of step S213.

[0121] (S215) If terminal 20B receives the reflected pilot signal in step S214, terminal 20B transmits communication quality information of the pilot signal to base station 10 (control device 5).

[0122] Through the above processing, the control device 5 has received communication quality information from terminal 20A at time slots t=1 and t=4, and therefore determines that base station 10 can perform wireless communication with terminal 20A at time slots t=1 and t=4. Similarly, the control device 5 determines that base station 10 can perform wireless communication with terminal 20B at time slots t=2 and t=5, and determines that base station 10 can perform wireless communication with terminal 20C at time slot t=3.

[0123] The control device 5 generates a radio link table based on the transmission of the pilot signal in each time slot and the reception result of the communication quality information. Next, the radio link table will be described.

[0124] FIG. 12 shows an example of the configuration of a wireless link table according to the second embodiment.

[0125] Based on the operation in the first cycle described above, the control device 5 creates a wireless link table as shown in FIG. 12, which indicates that the base station 10 and terminal 20A are capable of wireless communication at time slots t=1 and t=4, the base station 10 and terminal 20B are capable of wireless communication at time slots t=2 and t=5, and the base station 10 and terminal 20C are capable of wireless communication at time slot t=3, and stores the table in a specified memory 1002 (see FIG. 24).

[0126] The control device 5 refers to the wireless link table and creates the second and subsequent wireless resource allocation schedules for the base station 10 (S220). For example, the base station 10 creates a wireless resource allocation schedule in which wireless communication with the terminal 20A is assigned to wireless resources corresponding to time slots t=1 and t=4, wireless communication with the terminal 20B is assigned to wireless resources corresponding to time slots t=2 and t=5, and wireless communication with the terminal 20C is assigned to wireless resources corresponding to time slot t=3.

[0127] Next, returning to FIG. 11, the operation in the second period will be described.

[0128] Based on the radio resource allocation schedule created by the control device 5 in step S220, the base station 10 performs the following operations.

[0129] (S221) The base station 10 transmits a radio signal to the terminal 20A in time slot t=1.

[0130] (S222) The reflector 15 sets a phase shift pattern s=1 in the time slot t=1, and reflects the radio signal of step S221. The terminal 20A receives the reflected radio signal of step S222. The terminal 20A may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=1.

[0131] (S223) The base station 10 transmits a radio signal to the terminal 20B in time slot t=2.

[0132] (S224) The reflector 15 sets a phase shift pattern s=3 in the time slot t=2, and reflects the radio signal of step S223. The terminal 20B receives the reflected radio signal of step S224. The terminal 20B may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=2.

[0133] (S225) The base station 10 transmits a radio signal to the terminal 20C in time slot t=3.

[0134] (S226) The reflector 15 sets a phase shift pattern s=4 in the time slot t=3, and reflects the radio signal of step S225. The terminal 20C receives the reflected radio signal of step S226. The terminal 20C may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=3.

[0135] (S227) The base station 10 transmits a radio signal to the terminal 20A in time slot t=4.

[0136] (S228) The reflector 15 sets the phase shift pattern s=1 in the time slot t=4, and reflects the radio signal of step S227. The terminal 20A receives the reflected radio signal of step S228. The terminal 20A may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=4.

[0137] (S229) The base station 10 transmits a radio signal to the terminal 20B in time slot t=5.

[0138] (S230) The reflector 15 sets the phase shift pattern s=3 in the time slot t=5, and reflects the radio signal of step S229. The terminal 20B receives the reflected radio signal of step S230. The terminal 20B may transmit a radio signal to the base station 10 using the radio resource corresponding to this time slot t=5.

[0139] The base station 10, the reflector 15, and the terminals 20A, 20B, and 20C may perform the same operations as in the second period described above in the third and subsequent periods.

[0140] According to the above-mentioned process, the reflector 15 deletes unused phase shift patterns and operates based on a changed phase shift schedule generated using only used phase shift patterns. In the first cycle (S201 to S215) in which the base station 10 transmits a pilot signal, the control device 5 receives communication quality information from the terminal 20 in all time slots, and as a result, creates a radio resource allocation schedule that allocates time resources to all time slots. Therefore, in the second and subsequent cycles (S221 to S230) in which the base station 10 transmits a radio signal, the utilization efficiency of radio resources is improved compared to the first embodiment.

[0141] FIG. 13 is a diagram for explaining a method of changing the phase shift schedule by the reflector 15 according to the second embodiment.

[0142] 13, the cycle (first cycle) in which a pilot signal is transmitted is represented as cycle P, and the cycle (second and subsequent cycles) in which wireless resources are allocated and data communication is performed is represented as cycle D. A set of one cycle P and the cycle D up to the next cycle P is referred to as a PD set.

[0143] Next, a method for changing the phase shift schedule by the reflector 15 will be described with reference to FIG.

[0144] (S301) The reflector 15 uses the received power meter 16 to calculate the average of the received power (e.g., RSS) for each phase shift pattern included in the multiple PD sets. For example, the reflector 15 calculates the average of the received power of multiple phase shift patterns s=1, the average of the received power of multiple phase shift patterns s=2, the average of the received power of multiple phase shift patterns s=3, the average of the received power of multiple phase shift patterns s=4, and the average of the received power of multiple phase shift patterns s=5, which are included in the multiple PD sets. Then, the reflector 15 specifies an unused phase shift pattern from the calculation result. For example, if the average of the received power when the phase shift pattern s=2 and the average of the received power when the phase shift pattern s=5 are smaller than a predetermined threshold, the reflector 15 determines that the phase shift patterns s=2 and s=5 are not used. This threshold may be, for example, the average of the maximum and minimum values ​​of the received power when each phase shift pattern is used. Although the received power is detected by the pilot signal for any phase shift pattern during the period P, the received power is hardly detected for the unused phase shift pattern during the period D, so that the average value of the received power for each phase shift pattern is calculated as described above, and the average value of the received power for the unused phase shift pattern becomes smaller than the threshold value. Therefore, by the above process, the reflector 15 can recognize the unused phase shift pattern.

[0145] (S302) The reflector 15 deletes unused phase shift patterns and generates a modified phase shift schedule using only phase shift patterns that are being used.

[0146] (S303) The reflector 15 sets a phase shift pattern for each time slot of one period based on the changed phase shift schedule, whereby the phase shift pattern being used is set for each time slot of one period.

[0147] (S304) The reflector 15 may periodically return the changed phase shift schedule to the initial (default) phase shift schedule and perform the process of detecting unused phase shift patterns as described above. This allows the reflector 15 to update the phase shift schedule to adapt to the presence status and positional changes of the terminal 20.

[0148] (Embodiment 3) In the third embodiment, a method for measuring (estimating) the position of terminal 20 using radio waves (wireless signals) and reflector 15 will be described.

[0149] <Communication system configuration> FIG. 14 is a diagram illustrating an example of a configuration of a communication system 1 according to the third embodiment.

[0150] The communication system 1 includes a control device 5, a base station 10, a reflector 15, and terminals 20 (20A, 20B, 20C). The communication system 1 may include any number of control devices 5, base stations 10, reflectors 15, and terminals 20.

[0151] The reflector 15 is installed at a predetermined indoor position (for example, on an indoor wall) where it can receive radio waves from the base station 10. The terminal 20 is located in an indoor area at a position where it can receive radio waves reflected by the reflector 15. The area is not limited to indoors and may be outdoors.

[0152] Information such as the timing of switching the phase shift pattern in the reflector 15 and the number of phase shift patterns used in one period may be shared and synchronized between the control device 5, the base station 10, and the terminal 20 of the communication system 1.

[0153] The terminal 20 is present within the area and can receive radio waves transmitted by the base station 10 and reflected by a reflector 15 installed indoors. The terminal 20 periodically measures the RSS for each phase shift pattern set by the reflector 15, and notifies the control device 5 of communication quality information including the measured RSS via the base station 10.

[0154] The control device 5 includes, as its functions, a wireless resource allocation unit 101, a fingerprint database (DB) 102, and a matching determination unit 103.

[0155] The wireless resource allocation unit 101 optimizes a wireless resource allocation schedule for the terminals 20 (20A, 20B, 20C) using the method explained in the second embodiment, based on communication quality information from the terminals 20 (20A, 20B, 20C).

[0156] The fingerprint DB 102 is used to measure the location of the terminal 20 by a fingerprint method. The fingerprint DB 102 will be described in detail later.

[0157] Matching determination section 103 identifies fingerprint data that matches the measurement RSS data received from terminal 20 from fingerprint DB 102, and measures the position of terminal 20 within the area.

[0158] <Fingerprint DB> 14, an indoor area of ​​10 m×10 m square where terminal 20 may exist is divided into 1 m square grids, and the center of each grid is set as a reference point. In this case, the number of reference points is 100.

[0159] At each reference point, the RSS (reception strength) for each phase shift pattern is measured in advance, and this is stored as fingerprint DB 102. In fingerprint DB 102, a set of measured RSS for each phase shift pattern for one reference point is referred to as fingerprint data. As a result, as shown in the initial fingerprint DB of FIG. 18 described later, fingerprint DB 102 is created in which measured RSS (i.e., fingerprint data) for each phase shift pattern s=1 to 5 is associated with each reference point r. In FIG. 14, for ease of explanation, only switching of phase shift patterns in the horizontal direction is depicted, but switching of phase shift patterns in the vertical direction may also be included.

[0160] Next, a method for determining the location of terminal 20 using fingerprint DB 102 will be described.

[0161] For example, assume that terminal 20B located in a position within the area shown in FIG. 14 measures RSS corresponding to phase shift patterns s=1, 2, 3, 4, 5 as 0, 3, 10, 5, 0, respectively. In this case, the measured RSS data is a set of 0, 3, 10, 5, 0. Control device 5 compares this measured RSS data with each fingerprint data in fingerprint DB 102, and measures reference point r corresponding to fingerprint data that is closest to the measured RSS data (for example, has the highest cosine similarity) as the position of terminal 20. Note that measured RSS data may be interpreted as wireless environment information. In addition, in this embodiment, an example in which the position of terminal 20 is measured using the reception strength of radio waves as wireless environment information will be described, but the position of terminal 20 may be measured using the strength propagation delay time and / or propagation channel information instead of or together with the reception strength.

[0162] <Method of locating a terminal using a fingerprint DB with a quantum computer> The optimization of the wireless resource allocation schedule performed by the wireless resource allocation unit 101 and the matching process with the fingerprint DB 102 performed by the matching determination unit 103 can also be realized at high speed and with low power consumption using the quantum computer 30. However, the matching process described below can also be realized using a classical computer without using the quantum computer 30.

[0163] FIG. 15 is a flowchart showing an example of a process for locating the terminal 20 using the fingerprint DB 102 by using the quantum computer 30 according to the third embodiment.

[0164] (S401) Matching determination unit 103 loops steps S401 to S403 the same number of times as the number of reference points included in fingerprint DB 102. In each loop, matching determination unit 103 selects one unselected reference point. In the description of the loop, the selected reference point is referred to as a selected reference point.

[0165] (S402) Matching determination unit 103 calculates the cosine similarity between the measured RSS data and the fingerprint data corresponding to the selected reference point by the quantum algorithm "SWAP test" using quantum computer 30. The details of this calculation method will be described later.

[0166] (S403) Matching determination unit 103 loops steps S401 to S403 until all reference points included in fingerprint DB 102 have been selected, and after all reference points have been selected, proceeds to the next step S404. Note that matching determination unit 103 may use auxiliary quantum bits in a quantum superposition state to express the fingerprint data corresponding to all reference points in superposition, thereby calculating the cosine similarity with the fingerprint data corresponding to all reference points in a single SWAP test.

[0167] (S404) The matching determination unit 103 selects a reference point with the highest cosine similarity among the multiple cosine similarities calculated in the loop of S401 to S403 by the quantum algorithm "Grover Adaptive Search" using the quantum computer 30. Then, the control device 5 sets the selected reference point as the position of the terminal.

[0168] Next, the quantum algorithm "SWAP test" performed in step S402 in FIG. 15 will be described with reference to FIG.

[0169] FIG. 16 shows a SWAP test circuit according to the third embodiment that calculates the inner product of vectors |a〉 and |b〉 each having one quantum bit, that is, two elements.

[0170] The probability that the result is |0〉 when measuring the ancillary bit (the top quantum bit) is given by Equation 4 below.

[0171]

number

[0172] If we measure the ancillary bits K times and denote the number of times that the result is |0〉 by #|0〉, the following equation 5 will be 1 if |a〉 and |b〉 are the same, and close to 0 if they are different (if they are the same, p0 = (#|0〉) / K=1, or 0.5 if different).

[0173]

number

[0174] A classical vector with n elements can be represented by q = log2n quantum bits, so the larger the size n of the vector, the greater the exponential reduction in the amount of computation that can be achieved through quantum computing.

[0175] <Challenges> FIG. 17 is a diagram for explaining the fact that the fingerprint DB and the measured RSS data cannot be directly compared.

[0176] 17, when fingerprint DB 102 is created with an initial phase shift schedule and the phase shift schedule is changed as in embodiment 2, fingerprint DB 102 and the measured RSS data measured with the changed phase shift schedule cannot be directly compared because the arrangement of phase shift patterns with respect to the time slot sequence is different. Therefore, in embodiment 3, a positioning method that can position terminal 20 using fingerprint DB 102 even when the phase shift schedule is changed as in embodiment 2 will be described.

[0177] As described in the second embodiment, the reflector 15 autonomously changes the phase shift schedule, and this change is made based on the radio resource allocation schedule by the control device 5. Therefore, the control device 5 that generates the radio resource allocation schedule can infer how the reflector 15 changed the phase shift schedule.

[0178] <Positioning method 1> FIG. 18 is a diagram for explaining the positioning method 1 according to the third embodiment.

[0179] In the positioning method 1, the control device 5 estimates the phase shift schedule changed by the reflector 15, and rearranges the fingerprint DB 102 in accordance with the changed phase shift schedule. A specific example will be described below.

[0180] For example, when the control device 5 estimates based on the measured RSS data that the phase shift patterns of time slots t=1, 2, 3, 4, 5 in the changed phase shift schedule are s=1, 3, 4, 1, 3, respectively, it performs the following process.

[0181] That is, control device 5 sets the reference point sequence r=1-100 of phase shift pattern s=1 in initial fingerprint DB 102 as the reference point sequence for time slots t=1, 4 in the changed fingerprint DB, sets the reference point sequence r=1-100 of phase shift pattern s=3 in initial fingerprint DB 102 as the reference point sequence for time slots t=2, 5 in the changed fingerprint DB, and sets the reference point sequence r=1-100 of phase shift pattern s=4 in initial fingerprint DB 102 as the reference point sequence for time slot t=3 in the changed fingerprint DB. Control device 5 then measures the position of terminal 20 by identifying reference point r corresponding to the measured RSS data from the changed fingerprint DB using the method described above.

[0182] <Positioning method 2> FIG. 19 is a diagram for explaining a positioning method 2 according to the third embodiment.

[0183] In the positioning method 2, the control device 5 generates measured RSS data (hereinafter referred to as measured RSS data for matching) to be used for matching with the fingerprint DB 102, based on the measured RSS data in the phase shift schedule before the change and the measured RSS data in the phase shift schedule after the change. Note that the measured RSS data for matching may be read as wireless environment information for matching. For example, the control device 5 performs the processes of the following steps S501 to S504.

[0184] (S501) The control device 5 stores the measured RSS data in the pre-change phase shift schedule in a predetermined memory 1002 (see FIG. 24).

[0185] (S502) When there are multiple measured RSSs having a common phase shift pattern in the measured RSS data in the phase shift schedule before the change and the measured RSS data in the phase shift schedule after the change, the control device 5 calculates the average value of those measured RSSs and sets the average value as the measured RSS of the phase shift pattern of the measured RSS data for comparison. For example, as shown in Fig. 19, the control device 5 performs the following processes (1), (2), and (3).

[0186] (1) The control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=1 at time slot t=1 in the pre-change phase shift schedule, the measured RSS measured with phase shift pattern s=1 at time slot t=1 in the changed phase shift schedule, and the measured RSS measured with phase shift pattern s=1 at time slot t=4 in the changed phase shift schedule.Then, the control device 5 sets the average value as the measured RSS of phase shift pattern s=1 of the comparison measured RSS data.

[0187] (2) The control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=3 at time slot t=3 in the pre-change phase shift schedule, the measured RSS measured with phase shift pattern s=3 at time slot t=2 in the changed phase shift schedule, and the measured RSS measured with phase shift pattern s=3 at time slot t=5 in the changed phase shift schedule.Then, the control device 5 sets the average value as the measured RSS of phase shift pattern s=3 of the comparison measured RSS data.

[0188] (3) The control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=4 at time slot t=4 in the phase shift schedule before the change and the measured RSS measured with phase shift pattern s=4 at time slot t=3 in the phase shift schedule after the change. Then, the control device 5 sets the average value as the measured RSS of phase shift pattern s=4 of the measured RSS data for comparison.

[0189] (S503) For the measured RSS in the phase shift pattern deleted from the phase shift schedule before the change in the changed phase shift schedule, the control device 5 acquires the measured RSS measured with the same phase shift pattern in the phase shift schedule before the change from the measured RSS data stored in step S501, and sets the measured RSS of the phase shift pattern in the measured RSS data for comparison. For example, the control device 5 performs the following processes (1) and (2) as shown in FIG. 19.

[0190] (1) Since phase shift pattern s=2 has been deleted from the changed phase shift schedule, the control device 5 obtains (copies) the measured RSS for phase shift pattern s=2 from the measured RSS data saved in step S501, and sets this as the measured RSS for phase shift pattern s=2 of the measured RSS data for comparison.

[0191] (2) Since phase shift pattern s=5 has been deleted from the changed phase shift schedule, the control device 5 obtains (copies) the measured RSS for phase shift pattern s=5 from the measured RSS data saved in step S501, and sets it as the measured RSS for phase shift pattern s=5 of the measured RSS data for comparison.

[0192] (S504) Control device 5 measures the position of terminal 20 by identifying reference point r corresponding to the measured RSS data for verification from fingerprint DB 102 using the method described above.

[0193] In other words, when the wireless environment information (measured RSS data) is after the phase shift pattern has been replaced (when the phase shift schedule is changed), the control device 5 averages the reception strengths (measured RSS) of overlapping phase shift patterns in the wireless environment information before the phase shift pattern is replaced (when the phase shift schedule is changed) and the wireless environment information after the replacement (when the phase shift schedule is changed), and generates wireless environment information for comparison (measured RSS data for comparison) by treating the reception strength of the phase shift pattern that does not exist in the wireless environment information after the replacement as the reception strength of the same phase shift pattern in the wireless environment information before the replacement, and estimates the position of the terminal 20 in the area by comparing the wireless environment information for comparison with the fingerprint DB 102.

[0194] <Positioning method 3> FIG. 20 is a diagram for explaining a positioning method 3 according to the third embodiment.

[0195] In the positioning method 3, the control device 5 generates measured RSS data for matching with the fingerprint DB 102, based on the measured RSS data after the phase shift schedule is changed. For example, the control device 5 performs the following processes of steps S601 to S603.

[0196] (S601) When there is one or more measured RSSs for a common phase shift pattern in the measured RSS data for the changed phase shift schedule, the control device 5 calculates the average value of those measured RSSs and sets the average value as the measured RSS for that phase shift pattern of the measured RSS data for comparison. For example, the control device 5 performs the following processes (1), (2), and (3) as shown in Fig. 20.

[0197] (1) The control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=1 at time slot t=1 and the measured RSS measured with phase shift pattern s=1 at time slot t=4 in the changed phase shift schedule. Then, the control device 5 sets the average value as the measured RSS of the phase shift pattern s=1 of the measured RSS data for comparison.

[0198] (2) In the changed phase shift schedule, the control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=3 at time slot t=2 and the measured RSS measured with phase shift pattern s=3 at time slot t=5. Then, the control device 5 sets the average value as the measured RSS of the phase shift pattern s=3 of the measured RSS data for comparison.

[0199] (3) The control device 5 calculates the average value of the measured RSS measured in phase shift pattern s=4 at time slot t=3 in the changed phase shift schedule. Note that the average value in this case is the same as the measured RSS measured in phase shift pattern s=4 at time slot t=3. The control device 5 then sets the average value as the measured RSS of the phase shift pattern s=4 of the measured RSS data for comparison.

[0200] (S602) In the changed phase shift schedule, the control device 5 sets the measured RSS for the phase shift pattern deleted from the phase shift schedule before the change to 0, and sets the measured RSS for that phase shift pattern in the measured RSS data for verification. For example, the control device 5 performs the following processes (1) and (2) as shown in FIG. 20.

[0201] (1) Since the phase shift pattern s=2 has been deleted from the changed phase shift schedule, the control device 5 sets the measured RSS of the phase shift pattern s=2 in the measured RSS data for verification to 0.

[0202] (2) Since the phase shift pattern s=5 has been deleted from the changed phase shift schedule, the control device 5 sets the measured RSS of the phase shift pattern s=5 in the measured RSS data for verification to 0.

[0203] (S603) Control device 5 measures the position of terminal 20 by identifying reference point r corresponding to the measured RSS data for verification from fingerprint DB 102.

[0204] That is, in the wireless environment information (measured RSS data) after the phase shift pattern has been replaced (when the phase shift schedule is changed), the control device 5 averages the reception strengths (measured RSS) of overlapping phase shift patterns, sets the reception strengths of non-existent phase shift patterns to 0, and generates wireless environment information for comparison (measured RSS data for comparison), and estimates the position of the terminal 20 in the area by comparing the wireless environment information for comparison with the fingerprint DB 102.

[0205] <Positioning method 4> FIG. 21 is a diagram for explaining a positioning method 4 according to the third embodiment.

[0206] In positioning method 4, the control device 5 generates measured RSS data for matching, which is used for matching with the fingerprint DB 102, based on the measured RSS data before the phase shift schedule is changed and the measured RSS data after the phase shift schedule is changed. Positioning method 4 differs from positioning method 3 in that weighting is performed when generating the measured RSS data for matching. For example, the control device 5 performs the processes of the following steps S701 to S704.

[0207] (S701) The control device 5 stores the measured RSS data in the pre-change phase shift schedule in a predetermined memory 1002 (see FIG. 24).

[0208] (S702) When there are multiple measured RSSs having a common phase shift pattern in the measured RSS data in the phase shift schedule before the change and the measured RSS data in the phase shift schedule after the change, the control device 5 calculates the average value of those measured RSSs. Then, the control device 5 weights the average value based on the number of measured RSSs used to calculate the average value, and sets the average value as the measured RSS of that phase shift pattern of the measured RSS data for comparison. For example, the control device 5 performs the following processes (1), (2), and (3) as shown in FIG. 21.

[0209] (1) The control device 5 calculates an average value of the measured RSS measured with phase shift pattern s=1 at time slot t=1 in the pre-change phase shift schedule, the measured RSS measured with phase shift pattern s=1 at time slot t=1 in the changed phase shift schedule, and the measured RSS measured with phase shift pattern s=1 at time slot t=4 in the changed phase shift schedule. Since the number of measured RSS used to calculate the average value is "3", the control device 5 multiplies the average value by a weighting coefficient "3" to determine the measured RSS data for comparison as the measured RSS with phase shift pattern s=1.

[0210] (2) The control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=3 at time slot t=3 in the pre-change phase shift schedule, the measured RSS measured with phase shift pattern s=3 at time slot t=2 in the changed phase shift schedule, and the measured RSS measured with phase shift pattern s=3 at time slot t=5 in the changed phase shift schedule. Since the number of measured RSS used to calculate the average value is "3", the control device 5 multiplies the average value by a weighting coefficient "3" to determine the measured RSS data for comparison as the measured RSS for phase shift pattern s=3.

[0211] (3) The control device 5 calculates the average value of the measured RSS measured with phase shift pattern s=4 at time slot t=4 in the phase shift schedule before the change and the measured RSS measured with phase shift pattern s=4 at time slot t=3 in the phase shift schedule after the change. Since the number of measured RSS used to calculate the average value is "2", the control device 5 multiplies the average value by a weighting coefficient "2" to determine the measured RSS as the measured RSS for phase shift pattern s=4 of the measured RSS data for comparison.

[0212] (S703) For the measured RSS in the phase shift pattern deleted from the phase shift schedule before the change in the changed phase shift schedule, the control device 5 acquires (copies) the measured RSS measured with the same phase shift pattern in the phase shift schedule before the change from the measured RSS data saved in step S701, and sets it as the measured RSS of that phase shift pattern of the measured RSS data for comparison. For example, the control device 5 performs the following processes (1) and (2) as shown in FIG. 21.

[0213] (1) Since phase shift pattern s=2 has been deleted from the changed phase shift schedule, the control device 5 obtains (copies) the measured RSS for phase shift pattern s=2 from the measured RSS data saved in step S701, multiplies the measured RSS by a weighting coefficient of "1", and sets it as the measured RSS for phase shift pattern s=2 of the measured RSS data for comparison.

[0214] (2) Since phase shift pattern s=5 has been deleted from the changed phase shift schedule, the control device 5 obtains (copies) the measured RSS for phase shift pattern s=5 from the measured RSS data saved in step S701, multiplies the measured RSS by a weighting coefficient of “1”, and sets it as the measured RSS for phase shift pattern s=5 of the measured RSS data for comparison.

[0215] (S704) Control device 5 measures the position of terminal 20 by identifying reference point r corresponding to the measured RSS data for verification from fingerprint DB 102.

[0216] That is, in the process of the positioning method 2, the control device 5 generates matching environment information (matching measured RSS data) by weighting a value obtained by averaging the reception strengths (measured RSS) of overlapping phase shift patterns based on the number of overlaps. By weighting in this way, in the matching measured RSS data, the reception strength of a phase shift pattern that is measured relatively infrequently can be made relatively small, and the reception strength of a phase shift pattern that is measured relatively frequently can be made relatively large.

[0217] <Flowchart> FIG. 22 is a flowchart showing an example of processing performed by the control device 5 according to the third embodiment.

[0218] (S801) The control device 5 measures the RSS for all phase shift patterns at all reference points and generates the fingerprint DB 102.

[0219] (S802) The control device 5 receives the measured RSS in each time slot for one period from the terminal 20, and generates measured RSS data.

[0220] (S803) The control device 5 determines whether the measurement of the measurement RSS in step S802 was performed according to the changed phase shift schedule.

[0221] (S803: NO) If the measurement of the measured RSS in step S802 was performed according to the phase shift schedule before the change, the control device 5 advances the process to step S804.

[0222] (S804) Control device 5 identifies reference point r corresponding to the measured RSS data generated in step S802 from fingerprint DB 102, and measures the position of terminal 20. Then, this process ends.

[0223] (S803: YES) If the RSS measurement in step S802 was performed according to the changed phase shift schedule, the control device 5 advances the process to step S805.

[0224] (S805) The control device 5 measures the position of the terminal 20 by any one of the above-mentioned positioning methods 1 to 4. Then, this process ends.

[0225] The control device 5 may repeatedly perform the processes of steps S802 to S805.

[0226] Through the above process, the control device 5 can switch the method of matching with the fingerprint DB 102 depending on whether the RSS measurement was performed according to the phase shift schedule before the change or the phase shift schedule after the change.

[0227] Fig. 23 is a graph comparing the positioning errors of positioning methods 1 to 4 according to embodiment 3. In the graph shown in Fig. 23, the horizontal axis indicates SNR [dB], and the vertical axis indicates the magnitude of the positioning error.

[0228] From this graph, it can be seen that positioning methods 3 and 4 have relatively small positioning errors regardless of the magnitude of the SNR.

[0229] It can also be seen that the positioning methods 3 and 4 have smaller positioning errors than the case where positioning is performed without changing the phase shift schedule. That is, by changing the phase shift schedule as in the second embodiment and using the positioning methods 3 and 4, the positioning error can be reduced.

[0230] Moreover, in the positioning methods 2 and 4, when the terminal 20 moves significantly between before and after the change of the phase shift schedule, the positioning error is likely to be large. Therefore, in consideration of the possibility that the terminal 20 moves between before and after the change of the phase shift schedule, the positioning method 3 is considered to be more suitable than the other positioning methods 1, 2, and 4.

[0231] (Hardware configuration) The above-mentioned functional blocks of the control device 5 can be realized by a computer program.

[0232] FIG. 24 is a diagram showing a hardware configuration of a computer that realizes the functional blocks of the control device 5 by a computer program.

[0233] The computer 1000 includes a processor 1001, a memory 1002, a storage 1003, an input device 1004, an output device 1005, a communication device 1006, a GPU (Graphics Processing Unit) 1007, a reading device 1008, and a bus 1009.

[0234] The processor 1001, memory 1002, storage 1003, input device 1004, output device 1005, communication device 1006, GPU 1007, and reading device 1008 are connected to a bus 1009 and can transmit and receive data in both directions via the bus 1009.

[0235] The processor 1001 is a device that executes a computer program stored in the memory 1002 and realizes the above-mentioned functional blocks. Examples of the processor 1001 include a Central Processing Unit (CPU), a Micro Processing Unit (MPU), a controller, a Large Scale Integration (LSI), an Application Specific Integrated Circuit (ASIC), a Programmable Logic Device (PLD), and a Field-Programmable Gate Array (FPGA).

[0236] The memory 1002 is a device that stores computer programs and data operated by the computer 1000. The memory 1002 may include a read-only memory (ROM) and a random access memory (RAM).

[0237] The storage 1003 is configured as a non-volatile storage medium, and is a device that stores computer programs and data handled by the computer 1000. Examples of the storage 1003 include a hard disk drive (HDD) and a solid state drive (SSD).

[0238] The input device 1004 is a device that accepts data to be input to the processor 1001. Examples of the input device 1004 include a keyboard, a mouse, a touch pad, and a microphone.

[0239] The output device 1005 is a device that outputs data generated by the processor 1001. Examples of the output device 1005 include a display and a speaker.

[0240] The communication device 1006 is a device that transmits and receives data to and from other devices, such as a server device, via a communication network. The communication device 1006 may include a transmitting unit that transmits data and a receiving unit that receives data. The communication device 1006 may support either wired communication or wireless communication. An example of wired communication is Ethernet (registered trademark). Examples of wireless communication are IEEE802.11, Bluetooth, LTE, 4G, 5G, and 6G.

[0241] The GPU 1007 is a device that processes image rendering at high speed. The GPU 1007 may be used for AI (artificial intelligence) processing (e.g., deep learning). The GPU 1007 may also be used to simulate processing by the quantum computer described above.

[0242] The reader 1008 is a device that reads data from a recording medium such as a digital versatile disk read only memory (DVD-ROM) or a universal serial bus (USB) memory.

[0243] The functional blocks of the control device 5 may be realized as an LSI, which is an integrated circuit. These functional blocks may be individually integrated into one chip, or some or all of them may be integrated into one chip. Here, it is referred to as an LSI, but it may also be called an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. Furthermore, if an integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a different derived technology, it is natural that the functional blocks may be integrated using that technology.

[0244] (Summary of embodiments 1, 2, and 3) The above description of the first, second and third embodiments discloses the following techniques.

[0245] <Technology 1> The communication system 1 includes a base station 10 that performs wireless communication with at least one terminal 20 using radio waves, a reflector 15 that includes multiple reflecting elements and switches between multiple phase shift patterns with different propagation characteristics of radio waves by adjusting the amount of phase shift related to the reflection of the radio waves at each reflecting element, and a control device 5 that controls allocation of radio resources related to wireless communication between the base station 10 and each terminal 20. The reflector 15 switches the phase shift pattern for each of multiple time slots that constitute one period. The control device 5 stores, for each of multiple time slots, wireless link information (e.g., a wireless link table) that associates the base station 10 and the terminal 20 that can perform wireless communication using radio waves that pass through the reflector 15, and determines allocation of wireless resources in each time slot based on the wireless link information. As a result, the control device 5 can allocate radio resources by referring to the radio link information so that the base station 10 can wirelessly communicate with the terminal 20 using the reflector 15. This eliminates the need for channel estimation processing for designing a phase shift in the reflector 15. Furthermore, by each operator individually allocating radio resources, a plurality of operators can share a reflector without performing cooperative control between the operators.

[0246] <Technology 2> In the communication system 1 described in Technology 1, when one base station 10 performs wireless communication with multiple terminals 20 in one time slot, the control device 5 determines, in allocating wireless resources, to allocate different frequency resources to each of the multiple terminals 20. This allows the base station 10 to perform wireless communication with a plurality of terminals 20 in one time slot.

[0247] <Technology 3> In the communication system 1 described in Technology 1 or 2, the control device 5 identifies the terminal 20 with which the base station 10 can wirelessly communicate via the reflector 15 in each time slot based on communication quality information (e.g., measured RSS) including the reception quality of radio waves from the terminal 20 in each time slot of one period, and generates wireless link information (e.g., a wireless link table) that associates the base station 10 in each time slot with the identified terminal 20. This allows the control device 5 to refer to the wireless link information to identify the terminal 20 with which the base station 10 can wirelessly communicate using the reflector 15 in each time slot.

[0248] <Technology 4> In a communication system 1 described in any one of Techniques 1 to 3, a control device 5 calculates the communication volume per subcarrier and per time slot provided by a base station 10, and determines the allocation of radio resources in each time slot based on the communication volume required by each of a plurality of terminals 20 capable of wireless communication with the base station 10, so as to satisfy the communication volume required by all of the plurality of terminals 20 and to minimize the number of time slots. This enables the control device 5 to improve the utilization efficiency of radio resources.

[0249] <Technology 5> In the communication system 1 according to any one of the first to fourth aspects, the reflector 15 includes a received power meter 16 that measures received power. The reflector 15 calculates the frequency of wireless communication by the base station 10 for each phase shift pattern based on the received power measured by the received power meter 16, and changes the phase shift pattern of each time slot in one period to a phase shift pattern in which the frequency of wireless communication is equal to or higher than a predetermined threshold. This allows the reflector 15 to change the phase shift pattern of each time slot in one period to a phase shift pattern that is currently being used, thereby improving the efficiency of use of wireless resources in the communication system 1.

[0250] <Technology 6> In the communication system 1 described in Technique 5, the control device 5 pre-stores a fingerprint database 102 generated based on the reception strength of radio waves by the terminal 20 for each phase shift pattern before replacement at each of a plurality of positions included in an area reachable by radio waves passing through the reflector 15, and estimates the position of the terminal 20 in the area by comparing wireless environment information (e.g., measured RSS data) including the reception strength of radio waves by the terminal 20 at each time slot of one period against the fingerprint database 102. This allows the control device 5 to use the radio waves transmitted through the reflector 15 to estimate the position of the terminal 20 within the area.

[0251] <Technology 7> In the communication system 1 described in Technique 6, the control device 5 averages the reception strengths of overlapping phase shift patterns in the radio environment information after the phase shift patterns have been replaced, sets the reception strength of non-existent phase shift patterns to 0, and generates radio environment information for comparison (e.g., measured RSS data for comparison).The control device 5 estimates the position of the terminal 20 in the area by comparing the radio environment information for comparison with the fingerprint database 102. This allows the radio environment information after the phase shift pattern has been replaced to be collated with the fingerprint database 102, making it possible to estimate the position of the terminal 20 within the area.

[0252] <Technology 8> In the communication system 1 described in Technology 6, when the wireless environment information is after the phase shift pattern has been replaced, the control device 5 averages the reception strengths of overlapping phase shift patterns in the wireless environment information before the phase shift pattern replacement and the wireless environment information after the replacement, and generates wireless environment information for comparison by treating the reception strength of a phase shift pattern that does not exist in the wireless environment information after the replacement as the reception strength of the same phase shift pattern in the wireless environment information before the replacement, and estimates the position of the terminal 20 in the area by comparing the wireless environment information for comparison with the fingerprint database 102. This allows the radio environment information after the phase shift pattern has been replaced to be collated with the fingerprint database 102, making it possible to estimate the position of the terminal 20 within the area.

[0253] <Technology 9> In the communication system 1 described in Technique 8, the control device 5 generates verification environment information by weighting a value obtained by averaging the reception strengths of overlapping phase shift patterns based on the number of overlaps. This allows the radio environment information after the phase shift pattern has been replaced to be collated with the fingerprint database 102, making it possible to estimate the position of the terminal 20 within the area.

[0254] <Technology 10> As a communication method, a base station 10 transmits radio waves related to wireless communication, a reflector 15 is provided with a plurality of reflecting elements and switches between a plurality of phase shift patterns having different propagation characteristics of radio waves by adjusting the amount of phase shift related to the reflection of the radio waves at each reflecting element, switches the phase shift pattern for each of a plurality of time slots constituting one period, at least one terminal 20 is capable of receiving the radio waves transmitted from the base station 10 and reflected by the reflector 15, and a control device 5 stores wireless link information (e.g., a wireless link table) that associates, for each of a plurality of time slots, the base stations 10 and terminals 20 that are capable of wireless communication using radio waves passing through the reflector 15, and determines an allocation of wireless resources related to wireless communication between the base station 10 and each terminal 20 in each time slot based on the wireless link information. As a result, the control device 5 can refer to the wireless link information to allocate wireless resources so that the base station 10 can wirelessly communicate with the terminal 20 using the reflector 15. Therefore, channel estimation processing for designing the phase shift in the reflector 15 is not required.

[0255] <Technology 11> In a communication system 1 in which a base station 10 transmits radio waves related to wireless communication, a reflector 15 is provided with a plurality of reflecting elements and switches between a plurality of phase shift patterns having different propagation characteristics of the radio waves by adjusting the amount of phase shift related to the reflection of the radio waves at each reflecting element, the reflector 15 switches the phase shift pattern for each of a plurality of time slots constituting one period, and at least one terminal 20 is capable of receiving the radio waves transmitted from the base station 10 and reflected by the reflector 15, a control device 5 that controls the allocation of radio resources related to wireless communication between the base station 10 and each terminal 20 stores, for each of a plurality of time slots, radio link information (e.g., a radio link table) that associates the base station 10 and the terminal 20 that are capable of wireless communication using radio waves that pass through the reflector 15, and determines the allocation of radio resources in each time slot based on the radio link information. As a result, the control device 5 can refer to the wireless link information to allocate wireless resources so that the base station 10 can wirelessly communicate with the terminal 20 using the reflector 15. Therefore, channel estimation processing for designing the phase shift in the reflector 15 is not required.

[0256] (Embodiment 4) FIG. 25 is a diagram for explaining an overview of cell search in the 5G standard.

[0257] The base station 10 (gNB) transmits an SSB (SS / PBCH block) while switching the beam over time (i.e., while sweeping the beam). The terminal 20 (UE) detects and synchronizes with the base station (gNB, cell) (i.e., cell search) by receiving the SSB in the initial state (e.g., when the power is turned on). Note that the SSB may be read as detection information.

[0258] As shown in FIG. 25, the SSB includes a PSS (Primary Synchronization Signal), an SSS (Secondary Synchronization Signal), and a PBCH (Physical Broadcast Channel). The PSS is used for DL ​​(DownLink) signal synchronization and detection of part of the Call ID. The SSS is used for DL ​​signal synchronization and detection of the PCI (Physical Cell ID) of the cell. The PBCH is used to transmit the MIB (Master Information Block: basic system information) and to notify the SSB Index (beam index).

[0259] FIG. 26 is a diagram for explaining a problem that occurs when terminal 20 receives SSB via reflector 15. In FIG.

[0260] In the initial state, the terminal 20 cannot detect the presence of the reflector (SA-IRS), so the terminal 20 is required to be able to perform cell search using the same procedure regardless of whether it receives radio waves directly from the base station 10 or via the reflector 15.

[0261] As shown in FIG. 26, the base station 10 performs a beam sweep, and the reflector 15 also performs a beam sweep by switching the phase shift pattern as described in the above embodiment. In this case, it is possible to assign an SSB to each combination of the number of beam patterns m (m is a natural number equal to or greater than 1) of the base station 10 and the number of phase shift patterns n (n is a natural number equal to or greater than 1) of the reflector. For example, as shown in FIG. 26, the phase shift pattern 1 of the reflector 15 is assigned to the beam patterns 1 to m (for example, m=64) included in the first beam sweep of the base station, and the phase shift pattern 2 of the reflector 15 is assigned to the beam patterns 1 to m included in the second beam sweep of the base station 10, and this is repeated up to the phase shift pattern n of the reflector 15. In this case, (m×n) SSBs are transmitted. Furthermore, among these SSBs, only the SSB of the beam transmitted from the base station 10 toward the reflector 15 can reach the terminal 20 via the reflector 15. That is, the SSB reaches the terminal 20 via the reflector 15 only when the beam from the base station 10 is directed toward the reflector 15. Therefore, the method shown in Fig. 26 has a problem that it takes a long time for the terminal 20 receiving the beam via the reflector 15 to complete the cell search. This embodiment describes a method that allows the terminal 20 to complete the cell search in an environment where the beam is received via the reflector 15 in a time that is not much different from the time when the beam is received directly from the base station 10.

[0262] FIG. 27 is a diagram for explaining a method for implementing a cell search via a reflector 15 according to the fourth embodiment.

[0263] The base station 10 according to the fourth embodiment prepares a dedicated beam (hereinafter referred to as a dedicated beam 50) directed toward the reflector 15, and uses this dedicated beam for communication via the reflector 15. The dedicated beam is not switched over time (i.e., not swept) and is fixed in the direction of the reflector 15. For beams other than the dedicated beam (hereinafter referred to as a normal beam 51), the base station 10 performs sweeping as in the conventional manner for the terminal 20 that can directly communicate with the base station 10.

[0264] The reflector 15 switches the phase shift pattern in accordance with the transmission timing of the SSB from the base station 10. The reflector 15 acts as a substitute for the base station 10 by associating the reflected beam 52 of the reflector 15 with the SSB.

[0265] The base station 10 transmits an SSB using a dedicated beam 50 directed to the reflector 15, enabling the terminal 20 via the reflector 15 to perform a cell search in accordance with 5G. At this time, the terminal 20 does not need to be aware of whether or not it has received a beam via the reflector 15.

[0266] For example, the base station 10 transmits a dedicated beam 50 including SSB1 at the timing of transmitting a normal beam 51 including SSB1, and the reflector 15 reflects the dedicated beam 50 including SSB1 with a phase shift pattern corresponding to the SSB1 in accordance with the transmission timing of the SSB1 by the base station 10. Next, the base station 10 transmits a dedicated beam 50 including SSB2 at the timing of transmitting a normal beam 51 including SSB2, and the reflector 15 reflects the dedicated beam 50 including SSB2 with a phase shift pattern corresponding to the SSB2 in accordance with the transmission timing of the SSB2 by the base station 10. By repeating this, the terminal 20 can receive SSBs and perform a cell search without being aware of whether or not the beam has been received via the reflector 15.

[0267] FIG. 28 is a diagram showing an example of an operation sequence between the base station 10, the reflector 15, and the terminal 20 according to the fourth embodiment.

[0268] First, an example of the cell search operation will be described. The base station 10 transmits an SSB while sweeping a normal beam 51. At this time, the base station 10 also transmits a dedicated beam 50 directed toward the reflector 15, including an SSB corresponding to the SSB transmitted by the normal beam 51. The reflector 15 transmits the dedicated beam 50 while sweeping as a reflected beam 52. The terminal 20F that can directly communicate with the base station 10 receives the SSB by the normal beam 51 transmitted directly from the base station 10. The terminal 20G that can communicate with the base station 10 via the reflector 15 receives the SSB by the reflected beam 52 from the reflector 15. As a result, both the terminal 20F that can receive a beam directly from the base station 10 and the terminal 20G that can receive a beam from the base station 10 via the reflector 15 can receive the SSB in the same way and detect the base station 10 (i.e., perform a cell search).

[0269] Next, the operation of random access will be described. Terminal 20F, which can communicate directly with base station 10, performs random access with base station 10 using the beam that received the SSB. Terminal 20G, which can communicate with base station 10 via reflector 15, performs random access using reflected beam 52 that received the SSB and dedicated beam 50 between base station 10 and reflector 15. This allows both terminal 20F, which can communicate directly with base station 10, and terminal 20G, which can communicate with base station 10 via reflector 15, to notify base station 10 of their presence in the same way.

[0270] Next, the operation of communication of data and control information will be described. The base station 10 communicates data and control information with the terminal 20F that can communicate directly with the base station 10 by using a normal beam 51 directed toward the terminal 20F. For the terminal 20G that can communicate with the base station 10 via the reflector 15, the base station 10 communicates data, control information, etc. with the terminal 20G by using a dedicated beam 50 and a reflected beam 52 that is swept by the reflector 15 and directed toward the terminal 20G. This allows both the terminal 20F that can communicate directly with the base station 10 and the terminal 20G that can communicate with the base station 10 via the reflector 15 to communicate with the base station 10 in the same way.

[0271] FIG. 29 is a diagram for explaining a design example of a phase shift pattern switching schedule of the reflector 15 in the case of 120 kHz SCS (Subcarrier Spacing) according to the fourth embodiment.

[0272] In the case of 120 kHz SCS, one half-frame is made up of 40 slots. SSBs are placed in predetermined half-frames. FIG. 29 shows that SSBs are placed in half-frames 0, 4, .... A slot indicates a predetermined unit of time. SSBs are placed in predetermined slots. FIG. 29 shows that SSBs are placed in slots 0 to 7, 10 to 17, 20 to 27, and 30 to 37. DL (DownLink) and UL (UpLink) allocation is in slot units. One slot is made up of 14 OFDM symbols. SSBs are placed in predetermined OFDM symbols.

[0273] One half frame is one period of the phase shift pattern switching schedule. In other words, the same phase shift pattern switching schedule is used in all half frames. The phase shift pattern switching schedule of the reflector 15 is designed to switch the phase shift pattern in accordance with the transmission timing of the SSB of the base station 10. Since DL / UL allocation is in slot units, the phase shift pattern switching schedule is designed so that the phase shift pattern does not cross slots. This is the same in the cases of 15 kHz SCS and 30 kHz SCS, which will be described later. Furthermore, the phase shift pattern switching schedule is designed so that the phase shift pattern is allocated as fairly as possible. This is the same in the cases of 15 kHz SCS, 30 kHz SCS, and 240 kHz SCS, which will be described later.

[0274] In addition, the phase shift pattern switching schedule may be designed to assign phase shift patterns to slots 8, 9, 18, 19, 28, 29, 38, and 39, in which SSB is not placed, so that the number of times each phase shift pattern appears is as fair as possible when viewed in one half frame.

[0275] 29, of the OFDM symbols 0 to 13 constituting slot 0, SSB1 is placed in OFDM symbols 4 to 7, and SSB2 is placed in OFDM symbols 8 to 11. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 1 to the time of OFDM symbols 0 to 7, and phase soft pattern 2 to the time of OFDM symbols 8 to 13.

[0276] That is, two SSBs 1 and 2 are arranged in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 1 and 2 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0277] This allows the reflector 15 to transmit SSB1 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 1, and transmit SSB2 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 2.

[0278] 29, of OFDM symbols 14 to 27 constituting slot 1, SSB3 is placed in OFDM symbols 16 to 19, and SSB4 is placed in OFDM symbols 20 to 23. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 3 to the time of OFDM symbols 14 to 19, and phase soft pattern 4 to the time of OFDM symbols 20 to 27.

[0279] That is, two SSBs 3 and 4 are arranged in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 3 and 4 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0280] This allows the reflector 15 to transmit SSB3 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 3, and transmit SSB4 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 4.

[0281] Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can receive reflected beam 52 including an SSB corresponding to the SSB transmitted by base station 10 via normal beam 51 via reflector 15 in synchronization with the timing of the transmission of the SSB by base station 10. Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can perform a cell search at approximately the same time and in approximately the same manner as terminal 20F, which communicates directly with base station 10.

[0282] FIG. 30 is a diagram for explaining a first design example of a phase shift pattern switching schedule for the reflector 15 in the case of 15 kHz SCS according to the fourth embodiment.

[0283] In the case of 15 kHz SCS, one half frame consists of five slots. Figure 30 shows that in the case of 15 kHz SCS, there is a pattern in which SSB is allocated to slots 0 to 1, and a pattern in which SSB is allocated to slots 0 to 3.

[0284] 30, of the OFDM symbols 0 to 13 constituting slot 0, SSB1 is allocated to OFDM symbols 2 to 5, and SSB2 is allocated to OFDM symbols 8 to 11. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 1 to the time of OFDM symbols 0 to 6, and assign phase shift pattern 2 to the time of OFDM symbols 7 to 13.

[0285] That is, two SSBs 1 and 2 are arranged in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 1 and 2 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0286] This allows the reflector 15 to transmit SSB1 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 1, and transmit SSB2 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 2.

[0287] Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can receive reflected beam 52 including an SSB corresponding to the SSB via reflector 15 in accordance with the timing at which base station 10 transmits an SSB using a normal beam. Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can perform a cell search at approximately the same time and in approximately the same manner as terminal 20F, which communicates directly with base station 10.

[0288] FIG. 31 is a diagram for explaining a first design example of a phase shift pattern switching schedule for the reflector 15 in the case of 30 kHz SCS according to the fourth embodiment.

[0289] In the case of 30 kHz SCS, one half frame consists of 10 slots. Figure 31 shows that in the case of 30 kHz SCS, there is a pattern in which SSB is allocated to slots 0 to 1, and a pattern in which SSB is allocated to slots 0 to 3.

[0290] 31, of the OFDM symbols 0 to 13 constituting slot 0, SSB1 is allocated to OFDM symbols 4 to 7, and SSB2 is allocated to OFDM symbols 8 to 11. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 1 to the time of OFDM symbols 0 to 7, and assign phase shift pattern 2 to the time of OFDM symbols 8 to 13.

[0291] That is, two SSBs 1 and 2 are arranged in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 1 and 2 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0292] This allows the reflector 15 to transmit SSB1 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 1, and transmit SSB2 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 2.

[0293] 31, of OFDM symbols 14 to 27 constituting slot 1, SSB3 is allocated to OFDM symbols 16 to 19, and SSB4 is allocated to OFDM symbols 20 to 23. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 3 to the time of OFDM symbols 14 to 19, and assign phase shift pattern 4 to the time of OFDM symbols 20 to 27.

[0294] That is, two SSBs 3 and 4 are arranged in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 3 and 4 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0295] This allows the reflector 15 to transmit SSB3 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 3, and transmit SSB4 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 4.

[0296] Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can receive reflected beam 52 including an SSB corresponding to the SSB transmitted by base station 10 via normal beam 51 via reflector 15 in synchronization with the timing of the transmission of the SSB by base station 10. Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can perform a cell search at approximately the same time and in approximately the same manner as terminal 20F, which communicates directly with base station 10.

[0297] FIG. 32 is a diagram for explaining a second design example of the phase shift pattern switching schedule of the reflector 15 in the case of 30 kHz SCS according to the fourth embodiment.

[0298] In the case of 30 kHz SCS, one half frame consists of 10 slots. Figure 32 shows that in the case of 30 kHz SCS, there is a pattern in which SSB is allocated to slots 0 to 1, and a pattern in which SSB is allocated to slots 0 to 3.

[0299] 32, of the OFDM symbols 0 to 13 constituting slot 0, SSB1 is allocated to OFDM symbols 2 to 5, and SSB2 is allocated to OFDM symbols 8 to 11. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 1 to the time of OFDM symbols 0 to 6, and assign phase shift pattern 2 to the time of OFDM symbols 7 to 13.

[0300] That is, two SSBs 1 and 2 are arranged in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 1 and 2 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0301] This allows the reflector 15 to transmit SSB1 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 1, and transmit SSB2 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 2.

[0302] 32, of OFDM symbols 14 to 27 constituting slot 1, SSB3 is allocated to OFDM symbols 16 to 19, and SSB4 is allocated to OFDM symbols 22 to 25. In this case, the phase shift pattern switching schedule of reflector 15 is designed to assign phase shift pattern 3 to the time of OFDM symbols 14 to 20, and assign phase shift pattern 4 to the time of OFDM symbols 21 to 27.

[0303] That is, two SSBs 3 and 4 are included in one slot, and the phase shift pattern switching schedule of the reflector 15 is designed so that two phase shift patterns 3 and 4 are assigned to the one slot. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is placed is included in the time of one phase shift pattern.

[0304] This allows the reflector 15 to transmit SSB3 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 3, and transmit SSB4 contained in the dedicated beam 50 as a reflected beam 52 due to phase shift pattern 4.

[0305] Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can receive a reflected beam including an SSB corresponding to an SSB transmitted by base station 10 via a normal beam via reflector 15. Therefore, terminal 20G, which communicates with base station 10 via reflector 15, can perform a cell search at approximately the same time and in approximately the same manner as terminal 20F, which communicates directly with base station 10.

[0306] FIG. 33 is a diagram for explaining a design example of a phase shift pattern switching schedule for the reflector 15 in the case of 240 kHz SCS according to the fourth embodiment.

[0307] In the case of 240 kHz SCS, one half frame consists of 80 slots.

[0308] As shown in Fig. 33, in the case of 240 kHz SCS, unlike the above-mentioned 120 kHz SCS, 15 kHz SCS, and 30 kHz SCS, there are some places where SSBs are arranged across slots. Therefore, the phase shift pattern switching schedule is designed so that the phase shift pattern does not cross over between slot pairs, with a pair of two slots (hereinafter referred to as a slot pair) as a unit.

[0309] As shown in Fig. 33, among OFDM symbols 0 to 27 constituting the slot pair of slots 0 and 1, SSB1 is placed in OFDM symbols 8 to 11, SSB2 is placed in OFDM symbols 12 to 15, SSB3 is placed in OFDM symbols 16 to 19, and SSB4 is placed in OFDM symbols 20 to 23. In this case, the phase shift pattern switching schedule of the reflector 15 is designed to assign phase shift pattern 1 to the time of OFDM symbols 0 to 3, phase shift pattern 2 to the time of OFDM symbols 4 to 7, phase shift pattern 1 to the time of OFDM symbols 8 to 11, phase shift pattern 2 to the time of OFDM symbols 12 to 15, phase shift pattern 3 to the time of OFDM symbols 16 to 19, phase shift pattern 4 to the time of OFDM symbols 20 to 23, and phase shift pattern 3 to the time of OFDM symbols 24 to 27.

[0310] That is, four SSBs 1, 2, 3, and 4 are arranged in one slot pair, and the phase shift pattern switching schedule of the reflector 15 is designed so that the four phase shift patterns 1, 2, 3, and 4 are assigned to the one slot pair. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0311] As a result, reflector 15 can transmit SSB1 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 1, transmit SSB2 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 2, transmit SSB3 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 3, and transmit SSB4 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 4.

[0312] As shown in Fig. 33, among OFDM symbols 28-55 constituting the slot pair of slots 2 and 3, SSB5 is placed in OFDM symbols 32-35, SSB6 is placed in OFDM symbols 36-39, SSB7 is placed in OFDM symbols 40-43, and SSB8 is placed in OFDM symbols 44-47. In this case, the phase shift pattern switching schedule of the reflector 15 is designed to assign phase shift pattern 4 to the time of OFDM symbols 28-31, phase shift pattern 5 to the time of OFDM symbols 32-35, phase shift pattern 6 to the time of OFDM symbols 36-39, phase shift pattern 7 to the time of OFDM symbols 40-43, phase shift pattern 8 to the time of OFDM symbols 44-47, phase shift pattern 5 to the time of OFDM symbols 48-51, and phase shift pattern 6 to the time of OFDM symbols 52-55.

[0313] That is, four SSBs 5, 6, 7, and 8 are arranged in one slot pair, and the phase shift pattern switching schedule of the reflector 15 is designed so that the four phase shift patterns 5, 6, 7, and 8 are assigned to the one slot pair. Also, the phase shift pattern switching schedule is designed so that the time during which one SSB is arranged is included in the time of one phase shift pattern.

[0314] As a result, reflector 15 can transmit SSB 5 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 5, transmit SSB 6 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 6, transmit SSB 7 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 7, and transmit SSB 8 contained in dedicated beam 50 as reflected beam 52 with phase shift pattern 8.

[0315] In FIG. 33, phase shift patterns 7 and 8 appear only once among four slots (slots 0 to 3), resulting in unfair allocation. Therefore, the phase shift pattern allocation schedule is designed so that these phase shift patterns 7 and 8 are allocated more than other phase shift patterns in slots where SSBs are not allocated, such as slots 16 to 19, 36 to 79, .... This allows the phase shift patterns to be allocated as fairly as possible when viewed in one half frame (one period of the phase shift pattern switching schedule).

[0316] (Summary of the fourth embodiment) The above description of the fourth embodiment discloses the following technology.

[0317] <Technology 1> The communication system 1 includes a base station 10 that performs wireless communication with at least one terminal 20 using radio waves, a reflector 15 that includes multiple reflecting elements and switches between multiple phase shift patterns with different propagation characteristics of radio waves by adjusting the amount of phase shift related to the reflection of the radio waves at each reflecting element, and a control device 5 that controls allocation of radio resources related to wireless communication between the base station 10 and each terminal 20. The reflector 15 switches the phase shift pattern for each of multiple time slots that constitute one period. The control device 5 stores, for each of multiple time slots, wireless link information (e.g., a wireless link table) that associates the base station 10 and the terminal 20 that can perform wireless communication using radio waves that pass through the reflector 15, and determines allocation of wireless resources in each time slot based on the wireless link information. As a result, the control device 5 can refer to the wireless link information to allocate wireless resources so that the base station 10 can wirelessly communicate with the terminal 20 using the reflector 15. Therefore, channel estimation processing for designing the phase shift in the reflector 15 is not required.

[0318] <Technology 2> In the communication system 1 described in Technology 1, two pieces of detection information (e.g., SSB) for the terminal 20 to detect the base station 10 are arranged in one slot, which is a unit time constituting a radio resource, and two of the above-mentioned time slots (phase shift patterns) related to the reflector 15 are assigned to the one slot. This allows the reflector 15 to transmit two pieces of detection information (SSB) arranged in the slots by a reflected beam with a phase shift pattern assigned to each of the two time slots. Therefore, the terminal 20 that communicates with the base station 10 via the reflector 15 can also receive the detection information and detect the base station 10 (cell search) at approximately the same time and in approximately the same manner as the terminal 20 that communicates directly with the base station 10.

[0319] <Technology 3> In the communication system 1 described in Technology 2, the two assigned detection information are respectively called first detection information (e.g., SSB1) and second detection information (e.g., SSB2), the two assigned time slots are respectively called first time slot (e.g., phase shift pattern 1) and second time slot (e.g., phase shift pattern 2), and the reflector 15 reflects a beam including the received first detection information with a phase shift pattern (e.g., phase shift pattern 1) corresponding to the first time slot, and reflects a beam including the received second detection information with a phase shift pattern (e.g., phase shift pattern 2) corresponding to the second time slot. This allows the reflector 15 to transmit the first detection information by a reflected beam with a first phase shift pattern, and transmit the second detection information by a reflected beam with a second phase shift pattern. That is, the reflector 15 can transmit the detection information while sweeping the reflected beam, just as the base station 10 transmits the detection information while sweeping the normal beam.

[0320] <Technology 4> In the communication system 1 described in Technology 2 or 3, the base station 10 transmits a beam (e.g., a normal beam) in a first direction including first detection information, while also transmitting a dedicated beam in the direction of the reflector 15 including the first detection information, and transmits a beam (e.g., a normal beam) in a second direction including second detection information, while also transmitting the dedicated beam in the direction of the reflector 15 including the second detection information, and the beam including the first detection information or the second detection information received by the reflector 15 is the dedicated beam. As a result, the reflector 15 can receive a dedicated beam including the detection information from the base station 10 at the timing when the base station 10 transmits the detection information, and transmit a reflected beam including the detection information. Therefore, the terminal 20 that communicates with the base station 10 via the reflector 15 can also receive the detection information and detect the base station 10 (cell search) at approximately the same time and in approximately the same manner as the terminal 20 that communicates directly with the base station 10.

[0321] <Technology 5> In the communication system 1 described in Technology 1, a predetermined number of detection information (e.g., SSB) for the terminal 20 to detect the base station 10 is arranged in a slot pair of two slots, which is a time unit constituting the radio resource, and a time slot (phase shift pattern) related to the reflector 15 is assigned to the one slot pair in correspondence with each detection information, with a length equal to or longer than the time of each detection information, and equal to or more than the number of detection information. This allows the reflector 15 to transmit each piece of detection information arranged in a slot pair by a reflected beam with a phase shift pattern assigned to each time slot. Therefore, the terminal 20 that communicates with the base station 10 via the reflector 15 can also receive the detection information and detect the base station 10 (cell search) at approximately the same time and in approximately the same manner as the terminal 20 that communicates directly with the base station 10.

[0322] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, corrections, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also belong to the technical scope of the present disclosure. In addition, the components in the above-mentioned embodiments may be arbitrarily combined within the scope of the invention. [Industrial Applicability]

[0323] The techniques disclosed herein are useful for wireless communication using reflectors. [Explanation of symbols]

[0324] 1, 1a, 1b, 1c Communication Systems 2. Obstacles 5, 5A, 5B control device 10, 10A, 10B, 10C base station 15 Reflector 16 Received power meter 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G terminals 30 Quantum Computer 50 Dedicated Beam 51 Normal Beam 52 Reflected Beam 101 Radio resource allocation unit 102 Fingerprint DB 103 Matching Judgment Unit 1000 Computers 1001 Processor 1002 Memory 1003 Storage 1004 Input Device 1005 Output device 1006 Communication equipment 1007 GPU 1008 Reading device 1009 Bus

Claims

1. a base station that performs wireless communication with at least one terminal using radio waves; a reflector including a plurality of reflecting elements, the reflecting element adjusting a phase shift amount related to the reflection of the radio wave at each of the reflecting elements to switch between a plurality of phase shift patterns having different propagation characteristics of the radio wave; a control device for controlling allocation of radio resources related to radio communication between the base station and each of the terminals, The reflector switches the phase shift pattern for each of a plurality of time slots constituting one period, The control device includes: storing, for each of the plurality of time slots, wireless link information associating the base station and the terminal capable of wireless communication using the radio wave passing through the reflector; determining an allocation of the radio resources in each of the time slots based on the radio link information; Communication systems.

2. When one base station performs wireless communication with a plurality of terminals in one time slot, the control device determines to allocate different frequency resources to each of the plurality of terminals in the allocation of the wireless resources. The communication system according to claim 1 .

3. The control device includes: based on communication quality information including a reception quality of the radio wave of the terminal in each time slot of the one period, the base station identifies a terminal capable of wireless communication via the reflector in each time slot of the one period; generating the radio link information in which the base station and the identified terminal in each of the time slots are associated with each other; The communication system according to claim 1 .

4. The control device includes: Calculating the traffic volume per subcarrier and per time slot provided by the base station; determining an allocation of the wireless resources in each of the time slots based on a communication amount required by each of a plurality of terminals capable of wirelessly communicating with the base station, so as to satisfy the communication amount required by all of the plurality of terminals and to minimize the number of time slots; The communication system according to claim 1 .

5. The reflector includes a reception power meter for measuring reception power, The reflector is calculating a frequency of wireless communication by the base station for each of the phase shift patterns based on the received power measured by the received power meter; changing the phase shift pattern of each time slot of the one cycle to a phase shift pattern in which the frequency of execution of the wireless communication is equal to or higher than a predetermined threshold; The communication system according to claim 1 .

6. The control device includes: storing in advance a fingerprint database that is generated based on the reception intensity of the radio wave by the terminal for each of the phase shift patterns before replacement at each of a plurality of positions included in an area reachable by the radio wave via the reflector; estimating a location of the terminal in the area by comparing radio environment information including the strength of the radio waves received by the terminal in each time slot of the one period with the fingerprint database; 6. The communication system according to claim 5.

7. The control device includes: generating a comparison radio environment information by averaging the reception strengths of the overlapping phase shift patterns in the radio environment information after the phase shift pattern is replaced and setting the reception strengths of the non-existent phase shift patterns to 0; estimating a location of the terminal in the area by comparing the comparison radio environment information with the fingerprint database; 7. The communication system according to claim 6.

8. When the radio environment information is after the phase shift pattern is replaced, generating a comparison radio environment information by averaging the reception strengths of the overlapping phase shift patterns in the radio environment information before and after the phase shift pattern replacement and setting the reception strength of a phase shift pattern not present in the radio environment information after the replacement to the reception strength of the same phase shift pattern in the radio environment information before the replacement; estimating a location of the terminal in the area by comparing the comparison radio environment information with the fingerprint database; 7. The communication system according to claim 6.

9. The control device includes: weighting the average value of the reception strengths of the overlapping phase shift patterns based on the number of overlaps to generate the reference radio environment information; 9. The communication system according to claim 8.

10. Two pieces of detection information for the terminal to detect the base station are arranged in one slot, which is a unit time constituting the radio resource, and the detection information is an SS / PBCH block; Two of the time slots related to the reflector are assigned to one slot. The communication system according to claim 1 .

11. The two pieces of assigned detection information are defined as first detection information and second detection information, respectively; The two assigned time slots are a first time slot and a second time slot, respectively; The reflector is reflecting a beam including the received first detection information by the phase shift pattern corresponding to the first time slot; reflecting a beam including the received second detection information by the phase shift pattern corresponding to the second time slot; The communication system according to claim 10.

12. The base station, Transmitting a beam in a first direction containing the first detection information and a dedicated beam in the direction of the reflector containing the first detection information; Transmitting a beam in a second direction that includes the second detection information and transmitting the dedicated beam in the direction of the reflector that includes the second detection information; The beam including the first detection information or the second detection information received by the reflector is the dedicated beam.

12. The communication system of claim 11.

13. A predetermined number of pieces of detection information for the terminal to detect the base station are arranged in a slot pair of two slots, which is a time unit constituting the radio resource, and the detection information is an SS / PBCH block; The time slots related to the reflectors are assigned to one slot pair in response to each piece of detection information, and the number of timeslots is equal to or greater than the number of pieces of detection information, and the timeslots are assigned to one slot pair in response to each piece of detection information, and the number of timeslots is equal to or greater than the number of pieces of detection information. The communication system according to claim 1 .

14. A base station transmits radio waves related to wireless communication, a reflector including a plurality of reflecting elements, the reflector adjusting a phase shift amount relating to the reflection of the radio wave at each of the reflecting elements to switch between a plurality of phase shift patterns having different propagation characteristics of the radio wave, the reflector switching the phase shift pattern for each of a plurality of time slots constituting one period; At least one terminal is capable of receiving the radio wave transmitted from the base station and reflected by the reflector; a control device stores, for each of the plurality of time slots, radio link information associating the base station and the terminal capable of wireless communication using the radio wave passing through the reflector, and determines allocation of radio resources for wireless communication between the base station and each of the terminals in each of the time slots based on the radio link information; Communication methods.

15. A base station transmits radio waves related to wireless communication, a reflector including a plurality of reflecting elements, the reflector adjusting a phase shift amount relating to the reflection of the radio wave at each of the reflecting elements to switch between a plurality of phase shift patterns having different propagation characteristics of the radio wave, the reflector switching the phase shift pattern for each of a plurality of time slots constituting one period; A control device that controls allocation of wireless resources related to wireless communication between a base station and each of the terminals in a communication system in which at least one terminal is capable of receiving a radio wave transmitted from the base station and reflected by the reflector, the control device comprising: storing, for each of the plurality of time slots, wireless link information associating the base station and the terminal capable of wireless communication using the radio wave passing through the reflector; determining an allocation of the radio resources in each of the time slots based on the radio link information; Control device.

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