Base station equipment

Abstract

To provide better pre-compensation for at least one of the propagation delay and Doppler shift associated with the movement of wireless terminals. [Solution] A base station device is provided, comprising: an acquisition unit that acquires information indicating the characteristics of at least one of the propagation delay and Doppler shift of the signals received by each of a plurality of wireless terminals; an assignment unit that classifies the plurality of wireless terminals into a first group and a second group based on the characteristics of each of the plurality of wireless terminals, assigns a first time frame to the first group, and assigns a second time frame different from the first time frame to the second group; and a correction unit that corrects the characteristics of the first time frame in the time domain using a first correction value corresponding to the first group, and corrects the characteristics of the second time frame in the time domain using a second correction value corresponding to the second group, and transmits wirelessly.

Description

Technical Field

[0006] , , ,

[0005] , ,

[0001] The present disclosure relates to a base station device.

Background Art

[0002] Patent Document 1 describes that UE200s with a moving speed greater than a threshold may be grouped based on the moving speed of UE200, and control for applying specific Doppler compensation information to the UE group may be executed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1, for example, there is room for improvement in the pre-compensation of at least one of the propagation delay and Doppler shift associated with the movement of the wireless terminal.

[0005] An object of the present disclosure is to provide a technique that can more appropriately pre-compensate at least one of the propagation delay and Doppler shift associated with the movement of a wireless terminal in view of the above problems.

Means for Solving the Problems

[0006] A first aspect of the present disclosure provides a base station device comprising: an acquisition unit that acquires information indicating characteristics of at least one of the propagation delay and Doppler shift of signals received by each of a plurality of wireless terminals; an assignment unit that classifies the plurality of wireless terminals into a first group and a second group based on the characteristics of each of the plurality of wireless terminals, assigns a first time frame to the first group, and assigns a second time frame different from the first time frame to the second group; and a correction unit that corrects the characteristics of the first time frame in the time domain using a first correction value corresponding to the first group, and corrects the characteristics of the second time frame in the time domain using a second correction value corresponding to the second group, and transmits wirelessly. [Effects of the Invention]

[0007] In one respect, it is possible to more appropriately pre-compensate for at least one of the propagation delay and Doppler shift associated with the movement of wireless terminals. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the configuration of a base station device according to the embodiment. [Figure 2] This is a diagram showing an example configuration of a communication system according to the embodiment. [Figure 3] This figure shows an example of the hardware configuration of a base station device according to the embodiment. [Figure 4] This flowchart shows an example of processing by a base station device according to the embodiment. [Figure 5] This figure shows an example of grouping processing according to the embodiment. [Figure 6] This figure shows an example of grouping processing according to the embodiment. [Figure 7] This figure shows an example of a time frame according to the embodiment. [Figure 8] This figure shows an example of a time frame according to the embodiment. [Figure 9] This figure shows an example of a time frame according to the embodiment. [Figure 10] This figure shows an example of a time frame according to the embodiment. [Modes for carrying out the invention]

[0009] The principles of this disclosure will be described with reference to several exemplary embodiments. These embodiments are described for illustrative purposes only and should be understood as helping those skilled in the art to understand and implement this disclosure without implying any limitation on the scope of this disclosure. The disclosures described herein may be implemented in various ways other than those described below.

[0010] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this disclosure belongs.

[0011] Embodiments of the present disclosure will be described below with reference to the drawings. Each drawing is merely illustrative for illustrating one or more embodiments. Each drawing may be associated not only with one specific embodiment but also with one or more other embodiments. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps described in any of the drawings may be changed as appropriate.

[0012] (Embodiment 1) <Structure> Referring to FIG. 1, the configuration of the base station apparatus 10 according to the embodiment will be described. FIG. 1 is a diagram showing an example of the configuration of the base station apparatus 10 according to the embodiment. The base station apparatus 10 includes an acquisition unit 11, an allocation unit 12, and a correction unit 13. Each of these units may be realized by the cooperation of one or more programs installed in the base station apparatus 10 and the hardware such as the processor and memory of the base station apparatus 10.

[0013] The acquisition unit 11 acquires information indicating characteristics related to at least one of the propagation delay and Doppler shift of signals received from the base station apparatus 10 by each of a plurality of wireless terminals. The allocation unit 12 classifies the plurality of wireless terminals into a first group and a second group based on the characteristics, allocates a first time frame to the first group, and allocates a second time frame different from the first time frame to the second group.

[0014] The correction unit 13 corrects the characteristics of the first time frame in the time domain with a first correction value corresponding to the first group, and corrects the characteristics of the second time frame in the time domain with a second correction value corresponding to the second group, and then performs wireless transmission. Thereby, for example, at least one of the propagation delay and Doppler shift associated with the movement of the wireless terminal can be more appropriately pre-compensated. Therefore, for example, it is possible to appropriately communicate with a wireless terminal moving at high speed simultaneously with a plurality of base stations or while switching between a plurality of base stations.

[0015] (Embodiment 2) <System Configuration> Next, referring to FIG. 2, the configuration of the communication system 1 according to the embodiment will be described. FIG. 2 is a diagram showing a configuration example of the communication system 1 according to the embodiment. In the example of FIG. 2, the communication system 1 includes a base station device 10A, a base station device 10B, and a base station device 10C. Hereinafter, when there is no need to distinguish each of the base station devices 10A to 10C, it is simply referred to as "base station device 10". Further, the communication system 1 includes wireless terminals 20-1, 20-2, ··· wireless terminals 20-N (N is an integer of 2 or more). Hereinafter, when there is no need to distinguish each of the wireless terminals 20-1 to 20-N, it is simply referred to as "wireless terminal 20". Note that the numbers of the base station devices 10 and the wireless terminals 20 are not limited to the example of FIG. 2.

[0016] In the example of FIG. 2, each base station device 10 is connected so as to be able to communicate via a network N. Examples of the network N include, for example, a core network, the Internet, a LAN (Local Area Network), and a bus. Also, it is connected so as to be able to communicate by wireless communication (for example, RAT (Radio Access Technology)) of a mobile communication system. Examples of the mobile communication system include, for example, the fifth-generation mobile communication system (5G), the sixth-generation mobile communication system (6G, Beyond 5G), the fourth-generation mobile communication system (4G), and the third-generation mobile communication system (3G).

[0017] The base station device 10 transmits and receives radio waves and relays communication between the wireless terminal 20 and the network N. Note that the base station device 10 may be a virtualized base station (vRAN (virtual RAN)) in which the physical functions of the base station are separated by software.

[0018] The wireless terminal 20 may be, for example, an in-vehicle communication device installed in a vehicle, or a mobile terminal such as a smartphone owned by a user riding in the vehicle. Alternatively, the wireless terminal 20 may be, for example, a relay device (e.g., IAB (Integrated Access Backhaul), WAB (Wireless Access Backhaul)) that relays communication to a mobile terminal owned by a user riding in the vehicle.

[0019] <Hardware Configuration> Figure 3 shows an example of the hardware configuration of a base station device 10 according to an embodiment. In the example in Figure 3, the base station device 10 (computer 100) includes a processor 101, memory 102, and a communication interface 103. These parts may be connected by a bus or the like. The memory 102 stores at least a portion of the program 104. The communication interface 103 includes an interface necessary for communication with other network elements.

[0020] When program 104 is executed in cooperation with the processor 101 and memory 102, etc., the computer 100 performs at least some of the processing of embodiments of this disclosure. Memory 102 may be of any type. Memory 102 may, in non-limiting examples, be a non-temporary computer-readable storage medium. Memory 102 may also be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. Although only one memory 102 is shown for computer 100, computer 100 may have several physically different memory modules. Processor 101 may be of any type. Processor 101 may include one or more general-purpose computers, dedicated computers, microprocessors, digital signal processors (DSPs), and, in non-limiting examples, processors based on multicore processor architectures. Computer 100 may have multiple processors, such as application-specific integrated circuit chips that are time-dependent to a clock that synchronizes the main processor.

[0021] Embodiments of the present disclosure may be implemented in hardware or in dedicated circuitry, software, logic, or any combination thereof. Some embodiments may be implemented in hardware, while others may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device.

[0022] This disclosure also provides at least one computer program product tangibly stored on a non-temporary computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions contained in a program module, and is executed on a device on a target real or virtual processor to perform the processes or methods of this disclosure. The program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The functionality of the program module may be combined or divided among the program module as desired in various embodiments. The machine-executable instructions of the program module can be executed on a local or distributed device. On a distributed device, the program module can reside on both local and remote storage media.

[0023] Program code for performing the methods of this disclosure may be written in any combination of one or more programming languages. These program codes are provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device. When the program code is executed by the processor or controller, the functions / operations in the flowchart and / or block diagrams it implements are performed. The program code may run entirely on a machine, partially on a machine, partially as a standalone software package, partially on a machine, partially on a remote machine, or entirely on a remote machine or server.

[0024] The program, when loaded into a computer, includes a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically or otherwise propagating signals.

[0025] <Processing> Next, an example of processing by the base station device 10 according to the embodiment will be described with reference to Figures 4 to 10. Figure 4 is a flowchart of an example of processing by the base station device 10 according to the embodiment. Figures 5 and 6 are diagrams showing an example of grouping processing according to the embodiment. Figures 7 to 10 are diagrams showing an example of a time frame according to the embodiment. Note that the processing in Figure 4 may be executed at intervals such as periodic intervals.

[0026] In step S101, the acquisition unit 11 acquires information indicating the characteristics of at least one of the propagation delay and Doppler shift of the radio waves received by each wireless terminal 20 from each base station device 10. Here, the acquisition unit 11 may, for example, acquire (measure, estimate) the values ​​(characteristic values) of propagation delay and Doppler shift for each base station device 10 based on channel measurement information for one or more base station devices 10 (e.g., base station device 10A, base station device 10B, etc.) notified by the wireless terminal 20. In this case, the characteristic values ​​of each wireless terminal 20 may be calculated by the base station device 10 or the wireless terminal 20 based on a pilot signal transmitted from the base station device 10 and received by the wireless terminal 20. The pilot signal may be, for example, a signal known to both the base station device 10 and the wireless terminal 20.

[0027] Next, the allocation unit 12 classifies the multiple wireless terminals 20 into groups based on their characteristics (step S102). This allows wireless terminals 20 with different characteristics, such as Doppler shift and propagation delay, to be assigned different time frames. Furthermore, multiple wireless terminals 20 that can be considered to have similar characteristics, such as Doppler shift and propagation delay, can be assigned the same time frame.

[0028] The assignment unit 12 may, for example, classify the multiple wireless terminals 20 into groups such that the difference in characteristic values, which is at least one of the propagation delay and Doppler shift values ​​of each wireless terminal 20 included in each group, is less than or equal to a threshold.

[0029] In this case, the allocation unit 12 may determine the Doppler shift threshold based on the subcarrier spacing when performing wireless communication using, for example, Orthogonal Frequency-Division Multiplexing (OFDM). In this case, the allocation unit 12 may use, for example, a value corresponding to a specific percentage of the subcarrier spacing (for example, 7%) as the Doppler shift threshold.

[0030] Furthermore, the allocation unit 12 may determine the propagation delay threshold based on the cyclic prefix (CP) length attached to each OFDM symbol, for example, when performing wireless communication using an orthogonal frequency division multiplexing scheme. In this case, the allocation unit 12 may use, for example, a value corresponding to a specific percentage (e.g., 90%) of the CP length as the propagation delay threshold.

[0031] Furthermore, the allocation unit 12 may determine thresholds for at least one of Doppler shift and propagation delay based, for example, on at least one of the signal encoding and modulation scheme (MCS: Modulation and Coding Scheme). In this case, the allocation unit 12 may determine a larger threshold, for example, as the MCS index decreases. This is because, although a relatively small MCS index results in a lower achievable transmission rate, it also increases tolerance to the effects of frequency and timing offsets caused by Doppler shift and propagation delay. If the MCS is not determined when processing step S102, the allocation unit 12 may select a specific MCS from the selectable MCSs and determine thresholds based on the selected MCS. Alternatively, if the MCS is not determined when processing step S102, the allocation unit 12 may determine thresholds based on representative values ​​(e.g., average, most frequent, median) of the tolerance to frequency and timing offsets of multiple MCSs.

[0032] Furthermore, the assignment unit 12 may classify the multiple wireless terminals 20 into groups based on characteristic values, such as at least one of the propagation delay and Doppler shift values ​​of each wireless terminal 20 included in each group, using AI (Artificial Intelligence) or the like.

[0033] (An example of classification using information from other base station devices 10 to which it is connected) The assignment unit 12 may classify each wireless terminal 20 into groups based on information about other base station devices 10 to which each wireless terminal 20 is connected and the characteristic values ​​of each wireless terminal 20. In this case, the assignment unit 12 may provisionally include wireless terminals 20 that have selected the same base station device 10 as their connection destination in the same group. The example in Figure 5 shows an example of grouping by the assignment unit 12 of base station device 10B. In the example in Figure 5, wireless terminals 20-1 to 20-5 that have selected other base station devices 10A and their own base station device 10B as connection destinations (simultaneous connection to base station devices 10A and base station devices 10B) are classified into provisional group 501. In addition, wireless terminals 20-6 to 20-11 that have selected only base station device 10B as their connection destination are classified into provisional group 502.

[0034] The assignment unit 12 may then classify each wireless terminal 20 included in each provisional group into the group such that the difference in characteristic values, which is at least one of the propagation delay and Doppler shift, is below a threshold. In the example in Figure 5, each of the wireless terminals 20-1 to 20-5 classified in provisional group 501 is further classified into one of groups 511 to 513. Similarly, each of the wireless terminals 20-6 to 20-11 classified in provisional group 502 is further classified into one of groups 512 to 505.

[0035] Furthermore, if the wireless terminal 20 is connected to multiple base station devices 10, the allocation unit 12 may classify the wireless terminal 20 into groups based on the characteristic values ​​of each wireless terminal 20 from each of the multiple base station devices 10. This allows multiple wireless terminals 20 that are considered to be in similar locations to be classified into the same group. In the example in Figure 6, the characteristic values ​​611 to 615 of each wireless terminal 20 that are simultaneously connected to base station device 10A and base station device 10B are shown. The allocation unit 12 may also classify each wireless terminal 20 that has been classified into a provisional group into group 601 and group 602 such that the specific value for base station device 10A is below a threshold, and the specific value for base station device 10B is also below a threshold.

[0036] Next, the allocation unit 12 allocates a different time frame to each group (step S103). Here, the allocation unit 12 determines at least one of the time frame length and the frame position (frame index, etc.) for each group of wireless terminals 20. Then, if multiple wireless terminals 20 are allocated to the same time frame, the allocation unit 12 allocates wireless resources to each wireless terminal 20 within that time frame using time division multiplexing, frequency division multiplexing, or spatial division multiplexing, based on the channel information of each wireless terminal 20.

[0037] The allocation unit 12 may determine, for example, the time frame length to be allocated to a group and at least one of the position of the time frame on the time axis, based on the QoS (Quality of Service) value requested for each wireless terminal 20 included in the group and the number of wireless terminals 20 included in the group. In this case, the allocation unit 12 may determine a longer time frame length to be allocated to a group, for example, the higher the QoS value requested for each wireless terminal 20 included in the group and the larger the number of wireless terminals 20 included in the group. In this case, the allocation unit 12 may determine a longer time frame length, for example, the higher the sum of the QoS values ​​of each wireless terminal 20 included in the group.

[0038] Furthermore, the allocation unit 12 may determine the position on the time axis of the time frame to be allocated to a group to be earlier, for example, the higher the QoS value requested for each wireless terminal 20 included in the group, and the larger the number of wireless terminals 20 included in the group. In this case, the allocation unit 12 may, for example, make the time frame length longer and the position of the time frame earlier, for example, the higher the sum of the QoS values ​​of each wireless terminal 20 included in the group.

[0039] Furthermore, the allocation unit 12 may determine, for example, the length of the time frame to be allocated to the group and at least one of the position of the time frame on the time axis to be allocated to the group, based on at least one of the communication latency of each wireless terminal 20 included in the group and the past transmission rate. In this case, the allocation unit 12 may, for example, allocate the time frame earlier the higher the total value of the communication latency of each wireless terminal 20 included in the group. Alternatively, the allocation unit 12 may, for example, allocate the time frame longer and allocate the time frame earlier the lower the total value of the past transmission rate of each wireless terminal 20 included in the group. This can, for example, achieve proportional fairness.

[0040] Furthermore, the allocation unit 12 determines the length of the guard section to be provided at least at the beginning and end of each time frame allocated to each group. In this case, the allocation unit 12 may determine the length of the guard section according to, for example, the offset value (correction value) of the transmission timing of the data transmitted from the base station device 10 to each group. In this case, the allocation unit 12 may use, for example, a value obtained by adding a specific value to a representative value (e.g., average value, most frequent value, median value) of the transmission delay of each wireless terminal 20 included in a particular group.

[0041] In the example in Figure 7, time frames 711, 712, 713, and 714 are assigned to each group. In the example in Figure 7, a guard section 721 is set at the beginning of time frame 711, followed by a data transmission section 722. In time frame 712, a guard section 723 is set at the beginning, a guard section 725 at the end, and a data transmission section 724 is set between them. In time frame 713, a guard section 726 is set at the beginning, a guard section 728 at the end, and a data transmission section 727 is set between them. In time frame 714, a guard section 730 is set at the end, and a data transmission section 729 is set before it.

[0042] (Example of allocation in accordance with 5G specifications) In 5G systems, base stations are synchronized with high precision using UTC (Coordinated Universal Time) clocks, and multiple slot formats are defined in TDD (Time Division Duplex) to prevent interference between base stations and wireless terminals. As an example, the DDDSU (D: Downlink, U: Uplink, S: Special) format will be explained. In 5G systems, Timing Advance (TA) is applied to compensate for the deviation caused by propagation delay in uplink (UL) reception timing, which causes wireless terminals to advance the UL transmission timing. Therefore, a guard section is provided between DL and UL using an S slot (a special slot including the downlink to uplink switching period) so that wireless terminals can advance the UL transmission timing without conflicting with downlink (DL) reception.

[0043] Therefore, as shown in Figure 8, the allocation unit 12 may set time frames using S slots where guard intervals can be set as boundaries. This makes it possible to implement the technology of this disclosure while adhering to the current 5G specifications. In the example in Figure 8, time frame 811 and time frame 812 are set with S slots of the 5G specifications as boundaries. Furthermore, if the time frame length is to be made longer, the allocation unit 12 may set a single time frame that includes time frame 811 and time frame 812.

[0044] The 5G-specification S slot, like other slots, consists of 14 symbols, and each symbol can be flexibly configured to be a DL symbol, UL symbol, or F (Flexible) symbol that can be used as a guard section. Therefore, the allocation unit 12 can appropriately set the guard section even in a 5G system by selecting a format that ensures a guard section length of at least the required length for the S slot. The determined slot format can be communicated to the wireless terminal 20 via DCI (Downlink Control Information), as described in section 11.1 of 3GPP TS38.331.

[0045] Furthermore, there may be cases where the slot format cannot be changed dynamically. In particular, according to 3GPP TS38.331, the DL-UL slot format and the symbol format within the slot may be notified to the wireless terminal via RRC (Radio Resource Control) parameters. In that case, the allocation unit 12 may, for example, adjust the guard interval length set in the time frame so as not to exceed the guard interval that can be secured with the set slot format.

[0046] Alternatively, the allocation unit 12 may determine whether the guard interval length set in the time frame exceeds the guard interval that can be secured with the given slot format (defined in the 5G specification, etc.). If it does exceed the limit, the allocation unit 12 may control the system so as not to assign a signal (to assign empty data) to the symbols in the excess portion where DL or UL is assigned as the format. This allows the guard interval length to be extended regardless of the 5G specification format. ((Example of adding a guard section to account for automatic repeat-requests (ARQs)))

[0047] In a TDD system, an Automatic Repeat-Request (ARQ) is typically implemented to retransmit signals in the event of a communication failure. When allocating time frames in accordance with 5G specifications, the wireless terminal 20 is not given an opportunity to send an acknowledgment (ACK) or negative acknowledgment (NACK) to the base station equipment 10 when downlink communication fails until the next time frame is allocated. Generally, there is a time limit from the time the corresponding signal is received before sending back an ACK or NACK. If the next time frame is not allocated within the time limit, it will not be possible to properly send back a NACK even if communication fails.

[0048] Therefore, the allocation unit 12 may add a guard section for transmission timing correction between the UL slot and the subsequent DL slot. In this case, for example, in a 5G system, it may be defined as a new slot format as shown in Figure 9. This makes it possible, for example, to send back ACK / NACK for DL ​​communication within a single time frame.

[0049] In the example in Figure 9, S-slots 921 and 922 are added between the UL slot and the subsequent DL slot to be used as guard sections for transmission timing correction. S-slot 922 is used as a guard section between time frame 911 and time frame 912. In the example in Figure 10, in time frame 911, ACK / NACK is returned to DL slot 1011 by UL slot 1021, and ACK / NACK is returned to DL slot 1012 by UL slot 1022. This allows, for example, ACK / NACK during DL communication to be returned from the wireless terminal 20 to the base station device 10 within the same time frame. In the example in Figure 10, S-slots 921 and 922 each contain a UL symbol, an F symbol usable as a guard section, and a DL symbol.

[0050] ((Example of allocating wireless frames while considering ACK / NACK)) If a communication fails during UL communication, the base station needs to send a retransmission request to the wireless terminal. However, since there is no opportunity for DL ​​transmission until the next time frame is allocated, the retransmission request cannot be transmitted via DL. If the allocation of the next time frame is delayed, the retransmission request may not be properly executed.

[0051] Therefore, if there is a wireless terminal 20 that needs to send a retransmission request because communication failed during UL communication, the allocation unit 12 may allocate an earlier transmission time frame to the group to which the wireless terminal 20 belongs. This allows, for example, when UL communication fails, to expedite the allocation of the next time frame, enabling the base station device 10 to send a retransmission request to the wireless terminal 20 at an earlier stage.

[0052] (Example of allocating time frames while considering interference) The allocation unit 12 may assign the same time frame to each group of wireless terminals 20 whose characteristics, such as Doppler shift and propagation delay, are not considered to be the same, provided that the degree of spatial interference between the groups is below a threshold. This makes it possible to multiplex communications between multiple groups that do not spatially interfere with each other on the same time frame, thereby improving the throughput of each wireless terminal 20. In this case, the allocation unit 12 may estimate the degree of spatial interference between the first group and the second group based on, for example, the characteristic values ​​of each wireless terminal 20 included in the first group and the characteristic values ​​of each wireless terminal 20 included in the second group. In this case, the allocation unit 12 may determine, for example, whether the difference between the representative value of the characteristic value of each wireless terminal 20 included in the first group and the representative value of the characteristic value of each wireless terminal 20 included in the second group is greater than or equal to an interference determination threshold. If the difference is greater than or equal to the interference determination threshold, the first group and the second group are considered not to spatially interfere with each other, and therefore the same time frame may be assigned to the first group and the second group.

[0053] Next, the correction unit 13 pre-corrects (compensates) the characteristics of the time frame assigned to each group in the time domain using a correction value corresponding to each group (step S104). Here, the correction unit 13 pre-corrects the signals to be transmitted wirelessly from the base station device 10 to each group's wireless terminal 20 using a correction value corresponding to the group to which the wireless terminal 20 belongs before transmission. This allows the base station device 10 to wirelessly transmit signals pre-compensated with the same correction value to multiple wireless terminals 20 that can be considered to have similar characteristics, such as Doppler shift and propagation delay. Here, the correction unit 13 may use representative values ​​(e.g., mean, most frequent value, median) of the characteristic values ​​of each wireless terminal 20 included in a specific group as the correction value corresponding to the group.

[0054] The correction unit 13 may pre-correct the characteristics of the time frame assigned to each group in both the frequency domain and the time domain. In this case, the correction unit 13 may, for example, reduce the effect of the breakdown of OFDM orthogonality by performing time domain correction on a group basis, while pre-compensating in the frequency domain for the effects of frequency and timing offsets for each wireless terminal 20 that cannot be fully compensated for by time domain correction. In this case, the correction unit 13 may, for example, correct the signal to be transmitted to each wireless terminal 20 in the group in the frequency domain based on a correction value corresponding to the difference between the characteristic value of each wireless terminal 20 in the group and a representative value of the characteristic value of each wireless terminal 20 in the group.

[0055] <Other> This disclosure relates to a base station device for compensating for at least one of Doppler shift and propagation delay associated with the movement of a wireless terminal in a wireless communication system that communicates with a wireless terminal moving at high speed, for example, simultaneously with multiple base stations or while switching between multiple base stations. This disclosure can be applied, for example, when multiple base stations are connected to different control devices (e.g., CU (Central Unit), DU (Distributed Unit)), when multiple base stations are connected to and controlled by the same control device, when multiple base stations have different physical cell IDs, when multiple base stations have the same cell ID, etc.

[0056] To achieve high capacity in mobile communication systems such as cellular systems, wireless communication using high-frequency bands such as millimeter waves and terahertz waves, which offer wide bandwidths, is becoming increasingly important. When using high-frequency bands for mobile communication, the ability to utilize wide bandwidths enables high-capacity communication, but there are challenges such as high propagation loss depending on the frequency and significant interference from obstacles due to the high directivity of radio waves that do not easily bend around other objects.

[0057] One way to solve the former problem of propagation loss is beamforming technology, which strengthens the received level of radio signals transmitted in the direction of the communication target by performing appropriate phase control on the radio signals transmitted from multiple antenna elements. By using beamforming technology, it is possible to compensate for the large propagation loss in the high frequency band. Another way to solve the latter problem of straight-line propagation is a distributed antenna system (DAS). By extending the base station antenna and distributing multiple antennas, the probability of line-of-sight communication between the antenna and the radio terminal being blocked is reduced.

[0058] Furthermore, conventional macrocell systems have a large cell radius, and wireless terminals located at the cell edges suffer from reduced received power as they move further from the base station, as well as strong interference from adjacent cells, resulting in degraded communication quality. As one way to solve this problem, technologies that utilize and coordinate the operation of multiple base stations (also called antennas / cells / TRPs (Transmission Reception Points) / APs (Access Points), etc.) installed at relatively high density (e.g., Coordinated Multi-Point (CoMP), Multi-TRP, Single Frequency Network (SFN), Distributed MIMO) have been put into practical use or are under consideration.

[0059] In this context, for example, in the case of in-vehicle terminals that perform high-capacity communication by being mounted on high-speed moving objects such as trains and automobiles, or in wireless environments where wireless terminals move at high speeds, the movement of wireless terminals between the communication areas of multiple base stations becomes relatively frequent. Therefore, joint transmission (JT) and dynamic point selection (DPS) technologies between multiple base stations become particularly important.

[0060] On the other hand, when multiple base stations with different physical locations communicate with a wireless terminal, the wireless terminal is affected by different Doppler shifts and propagation delays for each base station. If the Doppler shift and propagation delay differ significantly from base station to base station, the communication quality may deteriorate during JT and DPS operation due to inter-subcarrier / inter-symbol interference in orthogonal frequency division multiplexing (OFDM), as well as phase rotation in the frequency / time direction of the channel.

[0061] In the case of DPS, in order to stabilize communication quality when switching base stations, it is necessary to compensate for sudden changes in Doppler shift and propagation delay. The same applies to JT, where the signals received by the wireless terminal from each base station antenna are subject to different Doppler shifts and propagation delays. It is difficult for the wireless terminal to simultaneously receive and compensate for the different Doppler shifts and propagation delays of multiple base station antennas, which can significantly degrade the communication quality of JT.

[0062] There are two methods for compensating for frequency offsets caused by Doppler shift and timing offsets caused by propagation delay at the base station transmitting the signal: "frequency domain pre-compensation" and "time domain pre-compensation." In wireless communication systems, when a signal is modulated, it is common to convert the signal mapped to the frequency domain to the time domain using OFDM modulation via IFFT (Inverse Fast Fourier Transform). "Frequency domain pre-compensation" is the process of applying correction to the frequency domain signal before modulation, and "time domain pre-compensation" is the process of applying correction to the time domain signal after modulation. For example, frequency domain compensation for frequency offsets caused by Doppler shift may be a process of rotating the phase of the frequency domain signal in the time direction according to the time symbol index. Similarly, frequency domain compensation for timing offsets caused by propagation delay may be a process of rotating the phase of the frequency domain signal in the frequency direction according to the frequency (subcarrier) index. Likewise, time domain compensation for frequency offsets caused by Doppler shift may be a process of rotating the phase of the time domain signal samples in the time direction according to the time sample index. Furthermore, time-domain compensation for timing offsets caused by propagation delay can also be achieved by shifting the transmission timing.

[0063] Frequency domain pre-compensation is a process performed in the frequency domain where the signal transmitted to each wireless terminal is mapped, making it possible to apply different corrections to each wireless terminal. However, it is impossible to compensate for inter-symbol interference and inter-subcarrier interference caused by frequency offset and timing offset during OFDM demodulation of the received signal using FFT (Fast Fourier Transform).

[0064] Time-domain pre-compensation can compensate for the effects of inter-symbol interference and inter-subcarrier interference. However, since this is a correction process applied to the time-domain signal after the signals of multiple wireless terminals have been combined by OFDM modulation, it is difficult to apply different corrections to each wireless terminal when communicating with multiple wireless terminals simultaneously. On the other hand, according to this disclosure, time-domain pre-compensation can be appropriately performed for each group of wireless terminals, thereby enabling more appropriate pre-compensation for at least one of the propagation delay and Doppler shift associated with the movement of wireless terminals.

[0065] <Variation> The base station device 10 may be a device contained in a single enclosure, but the base station device 10 of this disclosure is not limited to this. Each part of the base station device 10 may be implemented by cloud computing, for example, consisting of one or more computers. Such a base station device 10 is also included as an example of a "base station device" in this disclosure.

[0066] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0067] Some or all of the embodiments described above may also be described as follows, but are not limited to the following. Some or all of the elements (e.g., configuration and function) described in each appendix dependent on Appendix 1 may also be dependent on other independent appendices of other categories in a similar manner. Some or all of the elements described in any appendix may be applicable to various hardware, software, recording means, systems, and methods for recording software. (Note 1) An acquisition unit that acquires information indicating the characteristics of at least one of the propagation delay and Doppler shift of the signals received by each of multiple wireless terminals, An assignment unit classifies the plurality of wireless terminals into a first group and a second group based on the characteristics of each of the plurality of wireless terminals, assigns a first time frame to the first group, and assigns a second time frame different from the first time frame to the second group. A correction unit that corrects the characteristics of the first time frame in the time domain using a first correction value corresponding to the first group, and corrects the characteristics of the second time frame in the time domain using a second correction value corresponding to the second group, and transmits wirelessly. A base station device having the following features. (Note 2) The allocation unit classifies the plurality of wireless terminals into the first group and the second group such that the difference in the values ​​of the characteristics of each wireless terminal included in each group is less than or equal to a threshold. The base station equipment described in Appendix 1. (Note 3) The allocation unit classifies the plurality of wireless terminals into the first group and the second group based on information of other base station devices to which the plurality of wireless terminals are connected and the characteristics of each of the plurality of wireless terminals. Base station equipment as described in Appendix 1 or 2. (Note 4) When the plurality of wireless terminals are connected to a plurality of base station devices, the allocation unit classifies the plurality of wireless terminals into a first group and a second group based on the respective characteristics of each of the plurality of wireless terminals for each of the plurality of base station devices. Base station equipment as described in Appendix 3. (Note 5) The allocation unit determines at least one of the first time frame length and the position on the time axis of the first time frame based on the QoS (Quality of Service) value requested for each wireless terminal included in the first group and the number of wireless terminals included in the first group. Base station equipment as described in Appendix 1 or 2. (Note 6) The allocation unit determines the first time frame length to be longer and the position of the first time frame on the time axis to be earlier, at least one of the following: the higher the QoS value requested for each wireless terminal included in the first group, and the greater the number of wireless terminals included in the first group. Base station equipment as described in Appendix 5. (Note 7) The allocation unit determines at least one of the first time frame length and the position on the time axis of the first time frame based on the communication latency of each wireless terminal included in the first group and at least one of the past transmission rate. Base station equipment as described in Appendix 1 or 2. (Note 8) The allocation unit determines the length of a guard section to be provided at least at the beginning and end of the first time frame, based on the offset value of the transmission timing of the data transmitted from the base station device to the first group. Base station equipment as described in Appendix 1 or 2. (Note 9) If the guard interval length set in the first time frame exceeds the guard interval that can be secured in the slot format, the allocation unit will not assign a signal to the symbol of the excess portion for which the downlink or uplink is allocated as the slot format. Base station equipment as described in Appendix 1 or 2. (Note 10) The allocation unit adds an S slot between the uplink slot and the subsequent downlink slot to be used as a guard section for correcting the transmission timing. Base station equipment as described in Appendix 1 or 2. (Note 11) The allocation unit, if there is a wireless terminal that needs to send a retransmission request because communication failed during uplink communication, allocates an earlier transmission timing time frame to the group to which the wireless terminal belongs. Base station equipment as described in Appendix 1 or 2. (Note 12) The allocation unit assigns the first time frame to the first group and the third group if the difference between the representative value of the characteristic of each wireless terminal included in the first group and the representative value of the characteristic of each wireless terminal included in the third group is greater than or equal to the interference determination threshold. Base station equipment as described in Appendix 1 or 2. (Note 13) The correction unit corrects the signal to be transmitted to each wireless terminal in the first group in the frequency domain based on a correction value corresponding to the difference between the characteristic value of each wireless terminal in the first group and a representative value of the characteristic value of each wireless terminal in the first group. Base station equipment as described in Appendix 1 or 2. (Note 14) The base station equipment, Information is obtained from each of the multiple wireless terminals that shows the characteristics of at least one of the propagation delay and Doppler shift of the signals received by each of them. Based on the characteristics of each of the aforementioned wireless terminals, the aforementioned wireless terminals are classified into a first group and a second group, a first time frame is assigned to the first group, and a second time frame different from the first time frame is assigned to the second group. The characteristics of the first time frame are corrected in the time domain using a first correction value corresponding to the first group, and the characteristics of the second time frame are corrected in the time domain using a second correction value corresponding to the second group, and then transmitted wirelessly. Communication method. (Note 15) Information is obtained from each of the multiple wireless terminals that shows the characteristics of at least one of the propagation delay and Doppler shift of the signals received by each of them. Based on the characteristics of each of the aforementioned wireless terminals, the aforementioned wireless terminals are classified into a first group and a second group, a first time frame is assigned to the first group, and a second time frame different from the first time frame is assigned to the second group. The characteristics of the first time frame are corrected in the time domain using a first correction value corresponding to the first group, and the characteristics of the second time frame are corrected in the time domain using a second correction value corresponding to the second group, and then transmitted wirelessly. A program that instructs the base station equipment to perform a process. [Explanation of Symbols]

[0068] 1. Communication System 10 Base station equipment 11 Acquisition Department 12. Allocation Section 13 Correction section 20 Wireless terminals

Claims

1. An acquisition unit that acquires information indicating the characteristics of at least one of the propagation delay and Doppler shift of the signals received by each of multiple wireless terminals, An assignment unit classifies the plurality of wireless terminals into a first group and a second group based on the characteristics of each of the plurality of wireless terminals, assigns a first time frame to the first group, and assigns a second time frame different from the first time frame to the second group. A correction unit that corrects the characteristics of the first time frame in the time domain using a first correction value corresponding to the first group, and corrects the characteristics of the second time frame in the time domain using a second correction value corresponding to the second group, and transmits wirelessly. A base station device having the following features.

2. The allocation unit classifies the plurality of wireless terminals into the first group and the second group such that the difference in the values ​​of the characteristics of each wireless terminal included in each group is less than or equal to a threshold. The base station device according to claim 1.

3. The allocation unit classifies the plurality of wireless terminals into the first group and the second group based on information of other base station devices to which the plurality of wireless terminals are connected and the characteristics of each of the plurality of wireless terminals. The base station device according to claim 1 or 2.

4. When the plurality of wireless terminals are connected to a plurality of base station devices, the allocation unit classifies the plurality of wireless terminals into a first group and a second group based on the respective characteristics of each of the plurality of wireless terminals with respect to each of the plurality of base station devices. The base station device according to claim 3.

5. The allocation unit determines at least one of the first time frame length and the position on the time axis of the first time frame based on the Quality of Service (QoS) value requested for each wireless terminal included in the first group and the number of wireless terminals included in the first group. The base station device according to claim 1 or 2.

6. The allocation unit determines the first time frame length to be a longer value and the position of the first time frame on the time axis to be earlier, at least one of the following: the higher the QoS value requested by each wireless terminal included in the first group, and the greater the number of wireless terminals included in the first group. The base station device according to claim 5.

7. The allocation unit determines the length of the first time frame and the position of the first time frame on the time axis based on the communication waiting time of each wireless terminal included in the first group and at least one of the past transmission rate. The base station device according to claim 1 or 2.

8. The allocation unit determines the length of a guard section to be provided at least at the beginning and end of the first time frame based on the offset value of the transmission timing of the data transmitted from the base station device to the first group. The base station device according to claim 1 or 2.

9. If the guard interval length set in the first time frame exceeds the guard interval that can be secured in the slot format, the allocation unit will not assign a signal to the symbol of the excess portion for which the downlink or uplink is allocated as the slot format. The base station device according to claim 1 or 2.

10. The correction unit corrects the signal to be transmitted to each wireless terminal in the first group in the frequency domain based on a correction value corresponding to the difference between the characteristic value of each wireless terminal in the first group and a representative value of the characteristic value of each wireless terminal in the first group. The base station device according to claim 1 or 2.

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