Communication device and communication method

Abstract

This communication device comprises: an antenna unit including one or more antennas for receiving radio signals; a beam control unit for designating one or more reception beams to be applied to each antenna; a channel estimating unit for receiving the radio signals via each antenna and estimating a channel matrix relating to the radio signals; and a storage unit for storing estimated values of the channel matrix in a tensor in association with a transmission beam of each antenna applied to the radio signals and the reception beam of each antenna applied to the radio signals, each time at least one of the transmission beam of each antenna applied to the radio signals and the reception beam of each antenna applied to the radio signals is switched.

Description

Communication Apparatus and Communication Method

[0001] The present invention relates to a communication apparatus and a communication method in a wireless communication system.

[0002] In 3GPP (registered trademark) (3rd Generation Partnership Project), in order to achieve further increase in system capacity, further increase in data transmission rate, further reduction in latency in a radio section, and the like, studies are progressing on a wireless communication system called 5G or NR (New Radio) (hereinafter, this wireless communication system is referred to as "NR"). In 5G, various wireless technologies and network architectures are being studied to satisfy the requirement that the latency in a radio section is 1 ms or less while achieving a throughput of 10 Gbps or more (for example, Non-Patent Document 1 and Non-Patent Document 2).

[0003] Furthermore, various requirements are being studied for next-generation 6G. For example, such requirements include ultra broadband communication, mission critical communication, ultra massive connection, universal coverage, intelligent connection, ubiquitous sensing, and the like.

[0004] In order to achieve such requirements, as new concepts, the goals are set to be extensible (e.g., enabling effective use in the further future), easy-operational, customizable (e.g., enabling easier operation), and sustainable (e.g., cost reduction, a more robust configuration, resilience). In addition, as guaranteed communication, it is being studied to always guarantee a minimum level of performance.

[0005] Furthermore, the following technologies 1)-3) are widely used in mobile communications and wireless LANs (Local Area Networks).

[0006] 1) MIMO (Multi-Input Multi-Output): Multiple signals are transmitted simultaneously at the same time and frequency by using multiple antennas in the transmitter and receiver. 2) Channel Estimation: The response (channel) between the transmitter antenna and the receiver antenna is estimated. 3) Hybrid Beamforming: A system that performs MIMO using multiple antennas that can electronically switch the direction (beam) of radio wave transmission and reception. Digital beamforming and analog beamforming may be combined.

[0007] 3GPP TS 38.300 V18.3.0 (2024-09)3GPP TS 38.401 V18.3.0 (2024-09)

[0008] In hybrid beamforming, appropriately selecting the combination of transmitter and receiver antenna beams is crucial for improving MIMO multiplicity. This improvement requires information about the channel matrix. However, estimating the channel matrix for all the vast number of antenna beam combinations is difficult.

[0009] This invention has been made in view of the above points, and aims to improve the efficiency of the beamforming process in MIMO (Multi Input Multi Output) systems.

[0010] The disclosed technology provides a communication device comprising: an antenna unit including one or more antennas for receiving radio signals; a beam control unit for specifying one or more receiving beams to be applied to each of the antennas; a channel estimation unit for receiving the radio signals through each of the antennas and estimating a channel matrix relating to the radio signals; and a storage unit for storing the estimated channel matrix in a tensor relating the transmitting beam of each antenna and the receiving beam of each antenna applied to the radio signals each time at least one of the transmitting beam of each antenna applied to the radio signals switches.

[0011] According to the disclosed technology, the processing required for beamforming in MIMO (Multi Input Multi Output) systems can be made more efficient.

[0012] This figure shows an example configuration of a wireless communication system in an embodiment of the present invention. This figure shows an example of the functional configuration of a transmitter 10 and a receiver 20 in an embodiment of the present invention. This is a flowchart for explaining an example of processing (1) in an embodiment of the present invention. This figure shows an example of channel matrix configuration (1) in an embodiment of the present invention. This figure shows an example of channel matrix configuration (2) in an embodiment of the present invention. This figure shows an example of search (1) in an embodiment of the present invention. This figure shows an example of search (2) in an embodiment of the present invention. This is a flowchart for explaining an example of processing (2) in an embodiment of the present invention. This figure shows an example of the hardware configuration of a base station 10 or terminal 20 in an embodiment of the present invention. This figure shows an example of the configuration of a vehicle 2001 in an embodiment of the present invention.

[0013] Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention is applied are not limited to those described below.

[0014] In the operation of the wireless communication system according to the embodiments of the present invention, existing technologies may be used as appropriate. However, such existing technologies include, for example, existing LTE, but are not limited to existing LTE. Furthermore, the term "LTE" as used herein has a broad meaning that includes LTE-Advanced and LTE-Advanced and later technologies (e.g., NR), unless otherwise specified.

[0015] Furthermore, in the embodiments of the present invention described below, terms such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel), which are used in existing LTE systems, will be used. This is for convenience of description, and similar signals, functions, etc., may be called by other names. Also, the above terms in NR correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, etc. However, even if a signal is used in NR, it is not necessarily explicitly stated as "NR-".

[0016] Furthermore, in the embodiments of the present invention, the duplex system may be a TDD (Time Division Duplex) system, an FDD (Frequency Division Duplex) system, or any other system (for example, a Flexible Duplex).

[0017] Furthermore, in the embodiments of the present invention, "configuring" wireless parameters means that predetermined values ​​are pre-configured, or that wireless parameters notified from the base station 10 or terminal 20 are configured.

[0018] Figure 1 shows an example of the configuration of a wireless communication system in an embodiment of the present invention. The wireless communication system in the embodiment of the present invention includes a base station 10 and a terminal 20, as shown in Figure 1. Figure 1 shows one base station 10 and one terminal 20, but this is an example, and there may be multiple base stations 10 and terminals 20.

[0019] Base station 10 is a communication device that provides one or more cells and communicates wirelessly with terminal 20. The physical resources of the wireless signal are defined in the time domain and the frequency domain. The time domain may be defined by the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols, and the frequency domain may be defined by the number of subcarriers or resource blocks. Base station 10 transmits synchronization signals and system information to terminal 20. Synchronization signals are, for example, NR-PSS and NR-SSS. System information is transmitted, for example, in NR-PBCH and is also called broadcast information. Synchronization signals and system information may also be called SSB (SS / PBCH block). As shown in Figure 1, base station 10 transmits control signals or data to terminal 20 via DL (Downlink) and receives control signals or data from terminal 20 via UL (Uplink). Both base station 10 and terminal 20 are capable of transmitting and receiving signals using beamforming. Furthermore, both the base station 10 and the terminal 20 can apply MIMO (Multiple Input Multiple Output) communication to DL or UL. Also, both the base station 10 and the terminal 20 may communicate via Carrier Aggregation (CA) through secondary cells (SCell) and primary cells (PCell). Additionally, the terminal 20 may communicate via Dual Connectivity (DC) through the primary cell of base station 10 and the primary secondary cell group cell (PSCell) of another base station 10.

[0020] Terminal 20 is a communication device equipped with wireless communication capabilities, such as a smartphone, mobile phone, tablet, wearable device, or M2M (Machine-to-Machine) communication module. As shown in Figure 1, Terminal 20 receives control signals or data from the base station 10 via DL and transmits control signals or data to the base station 10 via UL, thereby utilizing various communication services provided by the wireless communication system. Terminal 20 also receives various reference signals transmitted from the base station 10 and performs propagation path quality measurement based on the reception results of said reference signals.

[0021] Furthermore, various requirements are being considered for the next generation of 6G. For example, these requirements may include ultra-broadband communication, mission-critical communication, ultra-massive connection, universal coverage, intelligent connection, and ubiquitous sensing.

[0022] Furthermore, these requirements may include ultra-high-speed communication, large-capacity communication, ultra-wide coverage, ultra-low power consumption, cost reduction, ultra-low latency, ultra-high reliability communication, ultra-high connectivity, and sensing.

[0023] To meet these requirements, the new concept aims for extensibility (e.g., making it more effective for future use), ease of operation, customizability (e.g., making it easier to operate), and sustainability (e.g., cost reduction, a more robust configuration, and resilience). Furthermore, guaranteed communication, ensuring a minimum level of performance at all times, is being considered.

[0024] Furthermore, the following techniques 1) to 3) are widely used in mobile communications and wireless LAN (Local Area Network).

[0025] 1) MIMO (Multi Input Multi Output): Multiple signals are multiplexed and transmitted at the same time and on the same frequency by using multiple antennas at the transmitter and the receiver. 2) Channel estimation: Estimating the response (channel) between the transmitter antenna and the receiver antenna. 3) Hybrid beamforming: A system that implements MIMO by using multiple antennas whose radio transmission / reception directions (beams) can be electronically switched. Digital beamforming and analog beamforming may be combined.

[0026] In order to improve the multiplexing degree of MIMO in hybrid beamforming, it is important to appropriately select the combination of antenna beams for the transmitter and the receiver. Channel matrix information is required to improve the multiplexing degree. However, it is difficult to estimate the channel matrix for all antenna beams that have an enormous number of combinations.

[0027] For example, consider the following system: ・Number of transmitter antennas: M ・Number of beam candidates per transmitter antenna: N ・Number of receiver antennas: P ・Number of beam candidates per receiver antenna: Q

[0028] In the above system, the number of possible beam combinations for the transmitter is N Ｍ ways, and the number of possible beam combinations for the receiver is Q Ｐ ways. Therefore, it is necessary to try up to N Ｍ Q Ｐ beam combinations. For example, when M=P=4 and N=Q=16, N Ｍ Q Ｐ =16 ４ ×16 ４ ≒4.29×10 ９ , which is an enormous number of combinations that need to be tried.

[0029] Accordingly, there is a demand for improving the efficiency of processing required for beamforming in MIMO (Multi Input Multi Output) systems.

[0030] Next, an example of the functional configuration of a base station 10 and a terminal 20 that perform the processing and operations described in the embodiment of the present invention will be described assuming that the base station 10 functions as a transmitter 10 and the terminal 20 functions as a receiver 20. However, the base station 10 may function as a receiver 20 and the terminal 20 may function as a transmitter 10. The base station 10 and the terminal 20 include functions to perform the embodiment. However, the base station 10 and the terminal 20 may each have only some of the functions in the embodiment.

[0031] <Transmitter 10> Figure 2 is a diagram showing an example of the functional configuration of the transmitter 10 in an embodiment of the present invention. As shown in Figure 2, the transmitter 10 has an antenna unit 101, a beam control unit 102, a reference signal transmission unit 103, an estimated channel tensor receiving unit 104, an estimated channel tensor storage unit 105, an estimated channel matrix retrieval unit 106, and an optimization execution unit 107. The functional configuration shown in Figure 2 is merely an example. Any functional classification and functional unit names are acceptable as long as they can perform the operations according to the embodiment of the present invention.

[0032] The antenna unit 101 consists of M antenna units and transmits the signal output from the reference signal transmission unit 103.

[0033] The beam control unit 102 receives control from the reference signal transmission unit 103 and controls the beams transmitted from each antenna unit 101. The beam control unit 102 controls the directivity of the antenna units 101 and may be able to set antenna units #1-#M of the transmitter 10 to each of N different beams.

[0034] The reference signal transmission unit 103 transmits a known signal sequence between the transmitter and receiver for channel estimation. A reference signal may be transmitted each time the transmitter beam (N beams) and the receiver beam (Q beams) are switched. The reference signal transmission unit 103 may also pre-acquire the transmitter beam number and receiver beam number applicable to the reference signal to be transmitted. The reference signal transmission unit may also be referred to as the transmission unit.

[0035] The estimated channel tensor receiving unit 104 receives the estimated channel tensor transmitted from the receiver 20. Note that the channel tensor is defined as Ψ∈C Ｍ×Ｎ×Ｐ×Ｑ This is a tensor that represents the following, and details will be described later. The estimated channel tensor receiver may also be referred to as the receiver.

[0036] The estimated channel tensor storage unit 105 sequentially reads the estimated channel matrix and the fourth-order channel tensor Ψ∈C Ｍ×Ｎ×Ｐ×Ｑ It is stored as follows. For example, the estimated channel matrix H∈C when the transmitter beam is the nth beam (1≦n≦N) and the receiver beam is the qth beam (1≦q≦Q). Ｍ×Ｐ Store this in the (:, n, :, q) elements of Ψ.

[0037] The estimated channel matrix reconstruction unit 106 reconstructs the estimated channel matrix by performing step S105, which will be described later, from the estimated channel tensor.

[0038] The optimization execution unit 107 inputs the antenna-beam tensor as an argument to the estimated channel matrix reproduction unit 106, and selects the beam of the transmitter 10 or receiver 20 based on the magnitude of a real-valued function that takes the output or reproduced channel matrix as an argument. The optimization execution unit may also be called the optimal beam selection unit.

[0039] As shown in Figure 2, the receiver 20 includes an antenna unit 201, a beam control unit 202, a reference signal reception and channel matrix estimation unit 203, an estimated channel tensor transmission unit 204, an estimated channel tensor storage unit 205, an estimated channel matrix retrieval unit 206, and an optimization execution unit 207. Note that the functional configuration shown in Figure 2 is merely an example. Any functional classification and functional unit names are acceptable as long as they can perform the operations according to the embodiment of the present invention.

[0040] The antenna unit 201 consists of P antenna units and inputs the received signal to the reference signal reception and channel matrix estimation unit 203.

[0041] The beam control unit 202 receives control from the reference signal reception and channel matrix estimation unit 203 and controls the received beam of each antenna unit 201. The beam control unit 202 may also control the directivity of the antenna units 201 and set the antenna units #1-#P of the receiver 20 to Q beams.

[0042] The reference signal receiving and channel matrix estimation unit 203 receives the reference signal transmitted from the transmitter 10 via the antenna unit 201 and estimates the channel matrix H∈C from the received reference signal. Ｍ×Ｐ The system estimates the following. For example, a reference signal may be received each time the transmitter beam (N beams) and the receiver beam (Q beams) are switched. The reference signal reception and channel matrix estimation unit 203 may also acquire in advance the transmitter beam number and the receiver beam number to be applied to the received reference signal. The reference signal reception and channel matrix estimation unit may also be referred to as the channel estimation unit.

[0043] The estimated channel tensor transmitting unit 204 transmits the estimated channel tensor to the transmitter 10. Note that the channel tensor is defined as Ψ∈C Ｍ×Ｎ×Ｐ×Ｑ This is a tensor that shows the following, and details will be explained later.

[0044] The estimated channel tensor memory unit 205 sequentially reads the estimated channel matrix and obtains the fourth-order channel tensor Ψ∈C Ｍ×Ｎ×Ｐ×Ｑ It is stored as follows. For example, when the transmitter beam is the nth beam (1 ≤ n ≤ N) and the receiver beam is the qth beam (1 ≤ q ≤ Q), the estimated H is stored in the (:, n, :, q) elements of Ψ. The estimated channel tensor storage unit may also be described as the storage unit.

[0045] The estimated channel matrix reconstruction unit 206 reconstructs the estimated channel matrix from the estimated channel tensor by performing step S105, which will be described later. The estimated channel matrix reconstruction unit may also be referred to as the reconstruction unit.

[0046] The optimization execution unit 207 inputs the antenna-beam tensor as an argument to the estimated channel matrix reproduction unit 206, and selects the beam of the receiver 20 or transmitter 10 based on the magnitude of a real-valued function that takes the output or reproduced channel matrix as an argument. The optimization execution unit may also be called the optimal beam selection unit.

[0047] Figure 3 is a flowchart illustrating an example of processing (1) in an embodiment of the present invention. The flowchart in Figure 3 assumes the following system: • Number of antennas in the transmitter: M • Number of beam candidates per antenna in the transmitter: N • Number of antennas in the receiver: P • Number of beam candidates per antenna in the receiver: Q

[0048] In step S101, the tensor Ψ∈C representing the channel Ｍ×Ｎ×Ｐ×Ｑ Substitute O (a tensor with all elements being 0) for H.

[0049] In step S102, all antennas of the transmitter 10 are set to the nth beam (1 ≤ n ≤ N), and all antennas of the receiver 20 are set to the qth beam (1 ≤ q ≤ Q), and the channel matrix H ∈ C Ｍ×Ｐ We estimate this.

[0050] In step S103, for the antenna number m of the transmitter 10 (1 ≤ m ≤ M) and the antenna number p of the receiver 20 (1 ≤ p ≤ P), H(m, p) is substituted for Ψ(m, n, p, q).

[0051] In step S104, steps S102 and S103 are repeated NQ times (1 ≤ n ≤ N, 1 ≤ q ≤ Q).

[0052] In step S105, the antenna beam combination of the transmitter 10 and the receiver 20 is set to x = (n １ ,n ２ , ..., n Ｍ ,q １ ,q ２ , ..., q Ｐ )∈{1,2,...,N-1,N} Ｍ ×{1, 2, ..., Q-1, Q} Ｐ Let's assume that the channel matrix H corresponding to x is as follows. ｘ ∈C Ｍ×ＰThe following procedure will be used to find H. Step a. H ｘ (m, p) to Ψ(m, n ｍ , p, q ｐ Substitute the following: Step b. Repeat Step a. MP times (1 ≤ m ≤ M, 1 ≤ p ≤ P).

[0053] Figure 4 is a diagram illustrating an example of channel matrix configuration (1) in an embodiment of the present invention. Figure 5 is a diagram illustrating an example of channel matrix configuration (2) in an embodiment of the present invention. Figures 4 and 5 show the channel matrix H to be obtained from the channel tensor H in the case where N = P = 2 and M = Q = 3. ｘ Here is an example of how to reconstruct it.

[0054] As shown in Figure 4, H （２，１，１，３） When finding Ψ(1,2,1,1), H （２，１，１，３） Substitute (1,1) and set Ψ(1,2,2,3) to H （２，１，１，３） Substitute (1,2) and set Ψ(1,1,2,1) to H （２，１，１，３） Substitute (1,2) and set Ψ(1,2,1,3) to H （２，１，１，３） Substitute into (2,2) and reconstruct.

[0055] As shown in Figure 5, the channel matrix H （２，１，１，３） This indicates that transmitting antenna #1 is set to beam onto scatterer #1, transmitting antenna #2 is set to beam onto receiving antenna, receiving antenna #1 is set to beam onto transmitting antenna, and receiving antenna #2 is set to beam onto scatterer #2.

[0056] When the number of beams differs for each antenna, the number of beams for each antenna in the transmitter and each antenna in the receiver do not necessarily have to be the same for all antennas. That is, the number of beams for the mth antenna of the transmitter is N. ｍ Q is the number of beams of the p-th antenna of the receiver. ｐ That is also acceptable.

[0057] In this case, the channel tensor Ψ has a magnitude of M × max (N). ｍ ) × P × max (Q ｐ This becomes a 4th-order complex tensor. The channel matrix is ​​estimated to be max(N). ｍ ) × max (Q ｐPerform this ) times, where n + max(N) ｍ During the ) × (q-1)th channel estimation, N ｍ For m such that ≤ n-1, the reference signal is not transmitted from the m-th transmitter antenna. Similarly, Q ｐ For p such that ≤ q-1, the p-th receiver antenna does not receive the reference signal. Therefore, for each (m, p), n ≥ N. ｍ +1 or q≧Q ｐ When the value is +1, let Ψ(m, n, p, q) = 0.

[0058] In cases where some information in the channel tensor is reduced, the channel tensor transmitted by the receiver to the transmitter may be changed to a partial tensor with some elements removed from the full-size (M × N × P × Q) tensor. For example, if the receiver selects the beams of all receiver antennas before transmitting the channel tensor to the transmitter, it is not necessary to transmit the channel tensor corresponding to the beams of the receiver antennas that were not selected to the transmitter. Therefore, the size of the fourth dimension of the channel tensor transmitted to the transmitter (corresponding to the number of receiver beams Q) may be reduced to 1.

[0059] If the transmitter does not change the antenna beam according to the channel tensor (for example, ZF (Zero Forcing) MIMO), it is not always necessary for the receiver to transmit the channel tensor to the transmitter.

[0060] Regarding antenna directivity, the term "antenna beam" may refer not only to a beam controlled by electronic methods (such as changing the excitation phase of an array antenna with a phase shifter), but also to a beam controlled by mechanical methods (such as changing the direction of the antenna by rotating a motor).

[0061] In a hybrid beamforming system, finding the beam combination that maximizes MIMO transmission capacity requires trying a vast number of combinations. Theoretically, the MIMO channel capacity is C = B * log ２ (I + γH Ｈ This can be calculated using H). However, to find the beam combination that maximizes C (which corresponds one-to-one with the channel matrix H), we need at most N Ｍ QＰ It is necessary to try out various H values. Therefore, we will explain a more efficient method for finding the beam combination that maximizes C.

[0062] Figure 6 shows an example of a search (1) in an embodiment of the present invention. Figure 7 shows an example of a search (2) in an embodiment of the present invention. Figure 8 is a flowchart illustrating an example of a process (2) in an embodiment of the present invention.

[0063] In step S201, the fourth-order channel tensor Ψ(m, n, p, q) ∈ C Ｍ×Ｎ×Ｐ×Ｑ From the sixth-order tensor G(m, m', n, p, p', q) ∈ C Ｍ×Ｍ×Ｎ×Ｐ×Ｐ×Ｑ This generates G(m, m', n, p, p', q) = Ψ(m, n, p, q) when m = m' and p = p', and G(m, m', n, p, p', q) = 0 otherwise.

[0064] In step S202, the antenna-beam tensor u(m', n) ∈ R ≧０ Ｍ×Ｎ , v(p', q)∈R ≧０ Ｐ×Ｑ Define the executable regions U and V for u and v as follows: U = {u ∈ R} ≧０ Ｍ×Ｎ | For any m' Σ １≦ｎ≦Ｎ u(m', n)≦1}, V={v∈R ≧０ Ｐ×Ｑ | For any p' Σ １≦ｑ≦Ｑ u(p', q) ≤ 1

[0065] Furthermore, by narrowing the range of regions U and V, we get U = {u∈R} ≧０ Ｍ×Ｎ | For any m' Σ １≦ｎ≦Ｎ u(m',n)=1}, V={v∈R ≧０ Ｐ×Ｑ | For any p' Σ １≦ｑ≦Ｑ Alternatively, we can set u(p', q) = 1.

[0066] Figure 6 shows an example of the region U in which the antenna-beam tensor u exists when M=1 and N=3. U may be a subset of the Euclidean space in which the feasible region of the tensor is restricted to a set expressed by a linear inequality. Conventional beam selection is a set U composed of discrete points. ｄｉｓｃｒｅｔｅ This can be considered as the optimization problem described above. As shown in Figure 6, U is U for each m (1 ≤ m ≤ M). ｄｉｓｃｒｅｔｅ This is the intersection of the sets whose convex hulls are taken.

[0067] In Figure 6, region U includes the origin O, but if the origin is not expected to be selected as any of the final solutions (for example, if all antennas are expected to always emit radio waves), then the set of discrete points is U', as shown in Figure 7. ｄｅｓｃｒｅｔｅ Unlike Figure 6, it is natural to consider this as a set excluding the origin. In this case, as shown in Figure 7, U' is U' for each m (1 ≤ m ≤ M). ｄｉｓｃｒｅｔｅ This is the intersection of the sets whose convex hulls are taken.

[0068] In step S203, channel matrix H(m,p) ∈ C is obtained from u, v, and G. Ｍ×Ｐ Multiple linear mapping f: (u, v, G) → H = Σ （ｍ'，ｎ，ｐ'，ｑ） Define G(m, m', n, p, p', q)u(m', n)v(p', q).

[0069] In step S204, C Ｍ×Ｐ Choose an arbitrary lower semicontinuous function c(H) above, and find the partial derivatives of c with respect to u and v, ∂c / ∂u(m', n) and ∂c / ∂v(p', q).

[0070] As an example of c(H), the MIMO channel capacitance function c(H) = B・log ２ det(I + γH Ｈ H) is a possible answer. Here, B represents the bandwidth, γ represents the signal-to-noise power ratio, and I represents the identity matrix.

[0071] ∂H / ∂u(m,m',n,p) = Σ(p',q)G(m,m',n,p,p',q)v(p',q) and ∂H / ∂v(m,p,p',q) = Σ(m',n)G(m,m',n,p,p',q)u(m',n). Also, if we can find the partial derivative of c with respect to H, ∂c / ∂H(m,p), then by the chain rule of differentiation, ∂c / ∂u = (∂c / ∂H)(∂H / ∂u) = Σ （ｍ，ｐ） ∂c / ∂H (m, p) ∂H / ∂u (m, m', n, p), ∂c / ∂v=(∂c / ∂H)(∂H / ∂v)=Σ （ｍ，ｐ） It can be calculated as ∂c / ∂H(m,p) and ∂H / ∂v(m,p,p',q).

[0072] In step S205, based on the obtained partial derivatives ∂c / ∂u and ∂c / ∂v, c is sequentially maximized (or minimized) on the product region U×V of U and V. For example, many methods are known, such as the steepest descent method and the conjugate gradient method. That is, c may be maximized or minimized by solving a maximization problem or a minimization problem.

[0073] According to the above embodiment, N Ｍ Q Ｐ While it is possible to construct all possible channel matrices, the number of channel estimations is limited to N. Ｍ Q Ｐ The number of iterations can be drastically reduced from one to NQ.

[0074] In other words, it is possible to streamline the processing required for beamforming in MIMO (Multi Input Multi Output) systems.

[0075] The block diagram (Figure 2) used in the description of the above embodiment shows functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may also be realized by combining the one or more devices with software.

[0076] Functions include, but are not limited to, judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In all cases, as mentioned above, the method of implementation is not particularly limited.

[0077] For example, the base station 10, transmitter 10, terminal 20, receiver 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 9 is a diagram showing an example of the hardware configuration of the base station 10, transmitter 10, terminal 20, and receiver 20 according to one embodiment of the present disclosure. The above-mentioned base station 10, transmitter 10, terminal 20, and receiver 20 may be physically configured as a computer device including a processor 1001, storage device 1002, auxiliary storage device 1003, communication device 1004, input device 1005, output device 1006, bus 1007, etc.

[0078] In the following explanation, the term "device" can be read as "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices.

[0079] Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and storage device 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of data reading and writing in the storage device 1002 and auxiliary storage device 1003.

[0080] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001.

[0081] Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10 shown in Figure 2 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Also, for example, the control unit 240 of the terminal 20 shown in Figure 3 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. The above processes have been described as being executed by one processor 1001, but they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may be transmitted from the network via a telecommunications line.

[0082] The storage device 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of the present disclosure.

[0083] The auxiliary storage device 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital multipurpose disk, a Blu-ray® disk), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The above-mentioned storage medium may also be a database, server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

[0084] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may be configured to include, for example, a high-frequency switch, duplexer, filter, frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting and receiving antenna, amplifier section, transmitting and receiving section, transmission path interface, etc., may be implemented by the communication device 1004. The transmitting and receiving section may be implemented in a physically or logically separated manner, with a transmitting section and a receiving section.

[0085] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0086] Furthermore, each device, such as the processor 1001 and the storage device 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0087] Furthermore, the base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0088] Figure 10 shows an example of the configuration of vehicle 2001. As shown in Figure 10, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in this disclosure may be applied to a communication device mounted on vehicle 2001, for example, to the communication module 2013.

[0089] The drive unit 2002 consists of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel, which is operated by the user.

[0090] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2029 installed in the vehicle 2001 are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0091] Signals from various sensors 2021 to 2029 include current signals from current sensor 2021 for sensing motor current, front or rear wheel rotation speed signals acquired by rotation speed sensor 2022, front or rear wheel air pressure signals acquired by air pressure sensor 2023, vehicle speed signals acquired by vehicle speed sensor 2024, acceleration signals acquired by acceleration sensor 2025, accelerator pedal depression signals acquired by accelerator pedal sensor 2029, brake pedal depression signals acquired by brake pedal sensor 2026, shift lever operation signals acquired by shift lever sensor 2027, and detection signals acquired by object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0092] The Information Service Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Service Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001. The Information Service Unit 2012 may include input devices that accept input from the outside (e.g., keyboard, mouse, microphone, switch, button, sensor, touch panel, etc.) and output devices that perform output to the outside (e.g., display, speaker, LED lamp, touch panel, etc.).

[0093] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0094] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-29 provided in the vehicle 2001.

[0095] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information with external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0096] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include the information based on the above input.

[0097] The communication module 2013 receives various information (traffic information, signal information, inter-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from the external device in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021-2029, etc., provided in the vehicle 2001.

[0098] (Summary of the embodiments)

[0099] (Clause 1) A communication device comprising: an antenna unit including one or more antennas for receiving a radio signal; a beam control unit for specifying one or more receiving beams to be applied to each of the antennas; a channel estimation unit for receiving the radio signal through each of the antennas and estimating a channel matrix relating to the radio signal; and a storage unit for storing the estimated value of the channel matrix in a tensor relating the transmitting beam of each antenna and the receiving beam of each antenna applied to the radio signal each time at least one of the transmitting beam of each antenna applied to the radio signal and the receiving beam of each antenna applied to the radio signal switches. (Clause 2) The communication device according to Clause 1, further comprising a transmitting unit for transmitting the tensor stored in the storage unit to a transmitter of the radio signal. (Clause 3) The communication device according to Clause 1, further comprising a reproduction unit for generating channel matrices corresponding to arbitrary transmitting beams of each antenna and arbitrary receiving beams of each antenna applied to the radio signal based on the tensor stored in the storage unit. (Clause 4) The communication device according to Clause 1, wherein the channel estimation unit estimates the channel matrix relating to the radio signal only when all the transmitting beams of each antenna applied to the radio signal are the same and all the receiving beams of each antenna applied to the radio signal are the same. (Clause 5) A communication device having an antenna unit including one or more antennas that transmit a radio signal; a beam control unit that designates one or more transmitting beams to be applied to each of the antennas; a transmitting unit that transmits the radio signal via each of the antennas each time at least one of the transmitting beams of each antenna applied to the radio signal and the receiving beams of each antenna applied to the radio signal switches; and a receiving unit that receives a tensor including an estimated value of the channel matrix relating to the radio signal in which the transmitting beams of each antenna applied to the radio signal and the receiving beams of each antenna applied to the radio signal are associated.(Clause 6) A communication method in which a communication device performs the following steps: specifying one or more receiving beams to be applied to each of one or more antennas that receive a radio signal; receiving the radio signal through each of the antennas and estimating a channel matrix relating to the radio signal; and, each time at least one of the transmitting beam of each antenna applied to the radio signal and the receiving beam of each antenna applied to the radio signal is switched, storing the estimated value of the channel matrix in a tensor relating the transmitting beam of each antenna applied to the radio signal and the receiving beam of each antenna applied to the radio signal.

[0100] Any of the above configurations can improve the efficiency of beamforming processing in a MIMO (Multi Input Multi Output) system. Furthermore, according to paragraphs 2 to 5, N Ｍ Q Ｐ While it is possible to construct all possible channel matrices, the number of channel estimations is limited to N. Ｍ Q Ｐ The number of iterations can be drastically reduced from one to NQ.

[0101] Furthermore, the embodiment may be configured as follows.

[0102] (Clause 1) A wireless communication system comprising a transmitter having one or more "transmitting antenna units" that transmit wireless signals, a "reference signal transmitting unit" that transmits reference signals from the antenna units, and a "transmitting beam control unit" that designates one or more beams of the subordinate "transmitting antenna units", and a receiver having one or more "receiving antenna units" that receive wireless signals, a "reference signal receiving and channel matrix estimation unit" that estimates the channel matrix between the "transmitting antenna units" and the "receiving antenna units" from the received reference signals, and a "beam control unit" that designates one or more beams of the subordinate "receiving antenna units". (Clause 2) The wireless communication system according to paragraph 1, wherein the "reference signal transmitting unit" transmits a reference signal for each beam number of the "transmitting antenna unit" designated by the "transmitting beam control unit" and each beam number of the "receiving antenna unit" designated by the "receiving beam control unit" in order to estimate the channel matrix between the "transmitting antenna unit" and the "receiving antenna unit", the "reference signal receiving and channel matrix estimation unit" receives the reference signal and estimates the channel matrix between the "transmitting antenna unit" and the "receiving antenna unit" from the content of the signal, and the transmitter and receiver each have an "estimated channel tensor storage unit" that stores the estimated value of the channel matrix in a channel tensor with two independent identifiers: the beam number designated by the "transmitting beam control unit" and the beam number designated by the "receiving beam control unit", respectively. (3) The wireless communication system according to paragraphs 1 and 2, wherein the transmitter has an "estimated channel tensor receiving unit" that receives the channel tensor transmitted from the receiver, and the receiver has an "estimated channel tensor transmitting unit" that transmits the channel tensor to the transmitter. (4) The wireless communication system according to paragraphs 1 and 2, wherein the transmitter and the receiver, or either thereof, has an "estimated channel matrix reproduction unit" that reproduces the channel matrix corresponding to an arbitrary beam number of the "transmitting antenna unit" and an arbitrary beam number of the "receiving antenna unit" by referring to the elements of the channel tensor stored in the "estimated channel tensor storage unit".(Clause 5) The wireless communication system according to paragraph 1, wherein the "reference signal transmitting unit" transmits the reference signal only when the beam number of the "transmitting antenna unit" designated by the "transmitting beam control unit" is the same for all "transmitting antenna units", and the "reference signal receiving and channel matrix estimation unit" receives the reference signal and estimates the channel matrix only when the beam number of the "receiving antenna unit" designated by the "receiving beam control unit" is the same for all "receiving antenna units".

[0103] Furthermore, the second paragraph above may be used to implement a function that estimates the channel matrix for each beam and sequentially stores it in the channel tensor. The third paragraph above may be used to implement a function that sends the channel tensor from the receiver to the transmitter. The fourth paragraph above may be used to implement a function that reconstructs the channel matrix from the channel tensor. The fifth paragraph above may be used to implement a function that performs high-speed channel tensor estimation by aligning the beams of all antennas in the same direction.

[0104] Furthermore, the embodiment may be configured as follows.

[0105] (Clause 1) A wireless communication system comprising: a transmitter and / or a receiver, or either one thereof, having an "estimated channel tensor storage unit" that stores a channel tensor, which is a multidimensional array storing the channel matrix between the transmitting antenna and the receiving antenna corresponding to each identifier, with the beam number of the transmitting antenna and the beam number of the receiving antenna as two independent identifiers; an "estimated channel matrix reproduction unit" that reproduces the channel matrix from the channel tensor stored in the "estimated channel tensor storage unit"; and an "optimal beam selection unit" that selects the optimal beam based on the channel matrix reproduced by the "estimated channel matrix reproduction unit". (Clause 2) The wireless communication system according to Clause 1, wherein the "optimal beam selection unit" selects the optimal beam based on the output value of a real-valued function that takes the channel matrix output from the "channel matrix reproduction unit" as an argument. (Clause 3) The wireless communication system according to Clause 2, wherein the "estimated channel matrix reproduction unit" calculates a channel matrix as the output of a function that takes the channel tensor stored in the "estimated channel tensor storage unit" and the antenna-beam tensor of the transmitter and the antenna-beam tensor of the receiver, or one of them, as arguments, and transmits it to the "optimal beam selection unit". (Clause 4) The wireless communication system according to Clause 3, wherein the "estimated channel matrix reproduction unit" restricts the feasible region of one or two tensors that are arguments of the multilinear function to a subset of Euclidean space that can be expressed by a linear inequality. (Clause 5) The wireless communication system according to Clause 3, wherein the "optimal beam selection unit" calculates the antenna-beam tensor by performing a minimization problem or a maximization problem using partial derivatives on the existence region of the antenna-beam tensor from a real-valued function that takes the channel matrix output from the "channel matrix reproduction unit" as an argument.

[0106] Furthermore, the second paragraph above may implement a function to select the optimal beam based on the magnitude of an evaluation function that takes the channel matrix as an argument. The third paragraph above may implement a function to output the channel matrix as a function of the antenna-beam tensor and the channel tensor. The fourth paragraph above may implement a function to restrict the feasible region of the antenna-beam tensor to a region that can be expressed by a linear inequality. The fifth paragraph above may implement a function to optimize using the partial derivatives of a real-valued function on the antenna-beam tensor region.

[0107] (Supplement to Embodiments) Embodiments of the present invention have been described above, but the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. The processing procedures described in the embodiments may be rearranged as long as they do not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to an embodiment of the present invention and the software operated by the processor of the terminal 20 according to an embodiment of the present invention may be stored in any suitable storage medium such as random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or other appropriate storage medium.

[0108] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or combinations thereof. Also, RRC signaling may be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0109] Each aspect / embodiment described in this disclosure may be applied to at least one of the following systems: LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (new Radio), W-CDMA®, GSM®, CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G).

[0110] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0111] In this specification, specific operations performed by the base station 10 may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with the terminal 20 can be performed by the base station 10 and at least one of the other network nodes (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station 10, the other network node may be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0112] The information or signals described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes.

[0113] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be transmitted to other devices.

[0114] The determination in this disclosure may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0115] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0116] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0117] The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0118] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0119] The terms “system” and “network” as used in this disclosure are interchangeable.

[0120] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0121] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0122] In this disclosure, terms such as "Base Station (BS)", "wireless base station", "base station equipment", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0123] A base station can accommodate one or more (e.g., three) cells. If a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a Remote Radio Head (RRH)). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage.

[0124] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0125] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0126] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate term.

[0127] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station may include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0128] Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.). In this case, the terminals 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc., may be interpreted as side channel.

[0129] Similarly, the term "user terminal" in this disclosure may be replaced with "base station." In this case, the base station may be configured to have the same functions as the user terminal described above.

[0130] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0131] The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0132] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0133] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0134] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0135] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0136] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0137] A wireless frame may consist of one or more frames in the time domain. Each of these frames in the time domain may be called a subframe. A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0138] Numerical logic may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerical logic may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain.

[0139] A slot may consist of one or more symbols in the time domain (such as OFDM (Orthogonal Frequency Division Multiplexing) symbols, SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols, etc.). A slot may also be a time unit based on neurologic.

[0140] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. Minislots may also be called subslots. Minislots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called a PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called a PDSCH (or PUSCH) mapping type B.

[0141] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms.

[0142] For example, one subframe may be called a Transmission Time Interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe in existing LTE (1 ms), a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0143] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, the base station schedules each terminal 20 to allocate wireless resources (such as the frequency bandwidth and transmission power available to each terminal 20) in TTI units. However, the definition of TTI is not limited to this.

[0144] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the actual time interval (e.g., number of symbols) in which the transport block, code block, code word, etc. are mapped may be shorter than the TTI.

[0145] Furthermore, if one slot or one mini-slot is referred to as a TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit for scheduling. In addition, the number of slots (number of mini-slots) that constitute this minimum time unit for scheduling may be controlled.

[0146] A TTI with a time length of 1 ms may be called a normal TTI, a long TTI, a normal subframe, a long subframe, a slot, etc. A TTI shorter than a normal TTI may be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, a mini slot, a sub slot, a slot, etc.

[0147] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0148] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0149] Furthermore, the time domain of the RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks.

[0150] One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc.

[0151] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0152] A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a particular neurology in a given carrier. These common RBs may be identified by an index of the RBs relative to a common reference point of the carrier. The PRBs may be defined and numbered within a given BWP.

[0153] A BWP may include a BWP for UL (UL BWP) and a BWP for DL ​​(DL BWP). One or more BWPs may be set within a single carrier for a UE.

[0154] At least one of the configured BWPs may be active, and the UE does not need to assume that it will transmit or receive a predetermined signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0155] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways.

[0156] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0157] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0158] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0159] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way.

[0160] This international patent application claims priority based on Japanese Patent Application No. 2025-028290, filed on 25 February 2025, and the entire contents of Japanese Patent Application No. 2025-028290 are incorporated herein by reference.

[0161] 10 Transmitter (may be a base station or terminal) 101 Antenna unit 102 Beam control unit 103 Reference signal transmission unit 104 Estimated channel tensor reception unit 105 Estimated channel tensor storage unit 106 Estimated channel matrix reproduction unit 107 Optimization execution unit 20 Receiver (may be a terminal or base station) 201 Antenna unit 202 Beam control unit 203 Reference signal reception and channel matrix estimation unit 204 Estimated channel tensor transmission unit 205 Estimated channel tensor storage unit 206 Estimated channel matrix reproduction unit 207 Optimization execution unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheel 2008 Rear wheel 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotation speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port (IO port)

Claims

1. A communication device comprising: an antenna unit including one or more antennas for receiving radio signals; a beam control unit for specifying one or more receiving beams to be applied to each of the antennas; a channel estimation unit for receiving the radio signals via each of the antennas and estimating a channel matrix relating to the radio signals; and a storage unit for storing the estimated value of the channel matrix in a tensor relating the transmitting beam of each antenna and the receiving beam of each antenna applied to the radio signals each time at least one of the transmitting beam of each antenna applied to the radio signals switches.

2. The communication device according to claim 1, further comprising a transmitting unit that transmits the tensor stored in the storage unit to the wireless signal transmitter.

3. The communication device according to claim 1, further comprising a reproduction unit that generates channel matrices corresponding to any transmit beam of each antenna applied to the radio signal and any receive beam of each antenna applied to the radio signal, based on the tensor stored in the memory unit.

4. The communication device according to claim 1, wherein the channel estimation unit estimates the channel matrix relating to the radio signal only when the transmitting beams of each antenna applied to the radio signal are all the same and the receiving beams of each antenna applied to the radio signal are all the same.

5. A communication device comprising: an antenna unit including one or more antennas for transmitting a radio signal; a beam control unit for specifying one or more transmit beams to be applied to each of the antennas; a transmitting unit for transmitting the radio signal via each of the antennas whenever at least one of the transmit beams of each antenna applied to the radio signal and the receive beams of each antenna applied to the radio signal switches; and a receiving unit for receiving a tensor including an estimated value of the channel matrix relating to the radio signal, in which the transmit beams of each antenna applied to the radio signal and the receive beams of each antenna applied to the radio signal are associated.

6. A communication method in which a communication device performs the following steps: specifying one or more receiving beams to be applied to each of one or more antennas that receive a radio signal; receiving the radio signal through each of the antennas and estimating a channel matrix relating to the radio signal; and, each time at least one of the transmitting beam of each antenna applied to the radio signal and the receiving beam of each antenna applied to the radio signal switches, storing the estimated value of the channel matrix in a tensor relating the transmitting beam of each antenna applied to the radio signal and the receiving beam of each antenna applied to the radio signal.

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