Communication systems and communication methods

Abstract

To provide a communication system and a communication method that satisfy various requirements.SOLUTION: The communication system comprises a base station that performs standard-compliant communication to a terminal, and an allocation determination device that receives an allocation request from the base station and determines a communication resource. The allocation determination device includes a first allocation determination unit and a second allocation determination unit. The first allocation determination unit outputs first allocation information within a first time after having received the allocation request. The second allocation determination unit outputs second allocation information within a first time after having received the allocation request. When one of the first allocation information and the second allocation information satisfies constraints defined by a communication standard, the allocation determination device transmits the one of the first allocation information and the second allocation information that satisfies the constraints to the base station. The base station communicates with the terminal using the resource corresponding to the first allocation information or the second allocation information transmitted from the allocation determination device.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] Embodiments of the present invention relate to a communication system and a communication method.

Background Art

[0002] In a wireless communication system, a large number of terminals execute communication simultaneously. The wireless communication system includes a resource allocation device that allocates resources for communication to the terminals. A terminal that wants to start wireless communication transmits an allocation request to the resource allocation device. The resource allocation device allocates resources to a plurality of terminals that have transmitted allocation requests, and outputs the resource allocation result to each terminal. Each terminal performs wireless communication using the allocated resources.

[0003] Various requirements such as high speed, large capacity, high reliability, and low latency are imposed on wireless communication systems. The resource allocation device is required to perform resource allocation processing in consideration of these requirements.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a communication system and a communication method that can satisfy various requirements. [[ID=!]]

Means for Solving the Problems

[0006] The communication system according to this embodiment comprises a base station that communicates with terminals in accordance with a communication standard, and an allocation determination device that receives allocation requests from the base station and determines the resources to be used for communication. The allocation request includes a first request and a second request. Each of the first and second requests includes terminal identification information, reference information about the terminal, and information indicating the start time of the allocation process. The reference information includes information regarding the allowable delay time for data transmitted and received by the terminal, the communication quality of data previously transmitted and received by the terminal, or the amount of data transmitted by the terminal. The allocation determination device executes the first process in response to the first request. Then, generate the first assignment information. A first assignment determination unit performs a second process different from the first process in response to a second request. Then, generate the second assignment information. It comprises a second allocation determination unit, and the first allocation determination unit, Start time of allocation decision process from Start time of allocation process to time The first assignment information is output to the second assignment determination unit. Start time of allocation decision process from Start time of allocation process to time Output second assignment information. Assign. The decision device transmits to the base station whichever of the first or second assignment information satisfies the constraints specified by the communication standard. The base station communicates with the terminal using the resources corresponding to the first or second assignment information transmitted from the assignment decision device. The first assignment decision unit searches for the first assignment information within the first search range. The second assignment decision unit searches for the second assignment information within the second search range. The first search range is wider than the second search range. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram illustrating an example of a communication system according to the embodiment. [Figure 2] A diagram illustrating an example of a control device. [Figure 3] A diagram illustrating an example of the first and second allocation determination units. [Figure 4] A diagram illustrating an example of the frame structure of a modulated signal in a fifth-generation mobile communication system. [Figure 5] A diagram illustrating the first example of resource block placement. [Figure 6] A diagram illustrating a second example of resource block placement. [Figure 7] A diagram illustrating a third example of resource block placement. [Figure 8] A diagram for explaining a configuration example of a resource block and an allocation example of a mini-slot. [Figure 9] A diagram for explaining the timing of allocation processing. [Figure 10] A diagram for explaining a first setting example at a first time and a second time. [Figure 11] A diagram for explaining a second setting example at a first time and a second time. [Figure 12] A flowchart for explaining an example of the processing of a control device. [Figure 13] A flowchart for explaining an example of the processing of a control device. [Figure 14] A diagram for explaining an example of the description format of allocation information. [Figure 15] A diagram for explaining an example of the format of allocation information. [Figure 16] A diagram for explaining an example of a first allocation determination unit and a second allocation determination unit. [Figure 17] A diagram for explaining another example of a first allocation determination unit and a second allocation determination unit. [Figure 18] A diagram for explaining an example of a communication system according to a first modification example. [Figure 19] A diagram for explaining an example of a communication system according to a second modification example. [Figure 20] A diagram for explaining an example of a communication system according to a third modification example. [Figure 21] A diagram for explaining an example of a communication system according to a fourth modification example. [Figure 22] A diagram for explaining an example of a communication system according to a fifth modification example. [Figure 23] A diagram for explaining a modification example regarding the configuration of an allocation determination device. [Figure 24] A diagram for explaining another modification example regarding the configuration of an allocation determination device.

Embodiments for Carrying Out the Invention

[0008] The embodiments will be described below with reference to the drawings. The following description illustrates devices and methods for realizing the technical concept of the embodiments, and the technical concept of the embodiments is not limited to the structure, shape, arrangement, material, etc. of the components described below. Modifications that a person skilled in the art can easily conceive of are naturally included in the scope of disclosure. In order to make the explanation clearer, the size, thickness, planar dimensions, or shape of each element may be schematically represented in the drawings with modifications from the actual embodiments. Multiple drawings may include elements with different dimensional relationships or ratios. In multiple drawings, the same reference numeral may be used for corresponding elements to omit redundant explanations. Some elements may be given multiple names, but these examples of names are merely illustrative and do not preclude the use of other names for these elements. Similarly, elements that do not have multiple names may also be given other names. In the following description, "connection" may include not only direct connections but also connections via other elements.

[0009] This embodiment will be described in detail below with reference to the drawings.

[0010] Figure 1 is a diagram illustrating an example of a communication system 10 according to an embodiment. Examples of communication systems include wireless LANs conforming to the IEEE 802.11 standard, and third-generation mobile communication systems (3G), fourth-generation mobile communication systems (4G or LTE-Advanced), and fifth-generation mobile communication systems (5G) standardized by the Third Generation Partnership Project (3GPP) (registered trademark). A 5G mobile communication system will be described as the communication system 10 in this embodiment. Alternatively, a sixth-generation mobile communication system (6G), which is being considered for standardization by 3GPP, may be used as the communication system 10.

[0011] 5G is expected to see a mix of services with diverse requirements, including high speed, large capacity, low latency, numerous simultaneous connections, high reliability, and fairness. To meet these diverse requirements, efficient resource utilization is crucial.

[0012] Resources include frequency, time, space (spatial stream), power, code, and orbital angular momentum. The communication system includes an allocation device that assigns resources to terminals. The resource allocation process is required to be performed in a very short time.

[0013] 5G systems use modulated signals, modulated by orthogonal frequency division multiplexing (OFDM) modulation, to perform wireless communication between terminals and base stations. The modulated signals used in 5G systems employ a mixed-numerology method, allowing for variable subcarrier spacing. 5G systems define units called slots, each containing a predetermined number (e.g., 14) OFDM symbols. Therefore, the modulated signals of 5G systems employing mixed-numerology can change the duration of these slots.

[0014] The 5G system defines a unit called a resource element. A resource element consists of one subcarrier and one OFDM symbol. Each resource element is identified by its subcarrier position and symbol position. The subcarrier position indicates the position in the frequency direction of the modulated signal. The symbol position indicates the position in the time direction of the modulated signal. One resource block contains multiple resource elements (for example, 12 subcarriers × 14 OFDM symbols = 168 resource elements). The 5G system also defines a unit called a resource block group, which is a collection of multiple resource blocks.

[0015] The 5G system uses the Massive MIMO (Multiple-Input and Multiple-Output) method. In the Massive MIMO method, multiple antennas are used for both transmission and reception.

[0016] The communication system 10 comprises a core network 30 and base stations 40. Figure 1 shows the communication system 10 including a single base station 40. However, the communication system 10 may include multiple base stations 40.

[0017] The core network 30 is the backbone communication network in the 5G system. The core network 30 relays packet communications between base stations 40 and other networks, or between multiple base stations 40.

[0018] At least one terminal 20-1, 20-2, ... 20-n is connected to base station 40. If terminals 20-1 to 20-n are not distinguished, each of them is referred to as terminal 20.

[0019] Terminal 20 may be an information processing device having wireless communication capabilities. Terminal 20 is equipped with an antenna. Terminal 20 is owned by the user. Terminal 20 is assigned a unique identification number. Terminal 20 transmits and receives modulated signals defined by the 5G system to and from the base station 40 via wireless communication. Terminal 20 may be portable by the user or may be installed in a specific location.

[0020] The base station 40 includes a communication device 42 and a control device 44. The communication device 42 is connected to the terminal 20 and the core network 30. The communication device 42 may also be connected to the core network 30 via signal lines.

[0021] The base station 40 transmits and receives modulated signals in accordance with the 5G method to and from at least one terminal 20 via wireless communication. The base station 40 relays packet communications between at least one terminal 20 and the core network 30.

[0022] The communication device 42 transmits and receives 5G modulated signals wirelessly with at least one terminal 20, in accordance with the control of the control device 44. The communication device 42 is equipped with an antenna.

[0023] The control device 44 controls the transmission and reception of the modulated signal at at least one terminal 20 and the communication device 42. For example, the control device 44 performs an assignment process to assign at least one terminal among the at least one terminal 20 to transmit and receive data using at least one communication block included in the modulated signal. The at least one communication block is identified by its position in the frequency direction and its position in the time direction in the modulated signal. The communication block may be a resource block group, a resource block, or a resource element.

[0024] The control device 44 may assign a resource block group, a resource block, or any resource element within a resource block to the terminal 20 that is to be assigned (hereinafter referred to as the assigned terminal).

[0025] The control device 44 may, in the allocation process, specify the subcarrier interval for at least one communication block included in the modulated signal. The control device 44 may, in the allocation process, specify the quadrature modulation scheme, transmission power, or coding rate for the data included in at least one communication block. The control device 44 may, in the allocation process, specify the propagation channel matrix used in the Massive MIMO scheme to the terminal to be allocated.

[0026] An allocation decision device 50 is connected to the base station 40. An allocation decision device 50 located near the base station 40 is also called a Mobile Edge Computing (MEC) server. The allocation decision device 50 may also be located inside the base station 40. The allocation decision device 50 may also be connected to the core network 30. An allocation decision device 50 connected to the core network 30 is also called a remote server. The allocation decision device 50 is connected to the control device 44.

[0027] Before performing the allocation process, the control device 44 outputs an allocation request to the allocation determination device 50. In wireless systems, resource allocation must be performed within a fixed time. An example of a fixed time is one slot, which is the smallest unit of scheduling (allocation processing) time. The fixed time may also be expressed in hours. The allocation determination device 50 outputs allocation information representing the resource allocation result to the control device 44 within one slot after receiving the allocation request.

[0028] There can be numerous evaluation methods for assessing whether the allocation result requested by the allocation determination device 50 is good or bad. For example, an evaluation value can be assigned to the allocation result using an evaluation formula. An example of an evaluation formula is expressed by one or more combinations of the following: transmission efficiency in the core network 30, latency (average latency or worst latency), fairness between terminals, latency achievement rate, etc. A highly-rated allocation result achieves communication with high transmission efficiency, low latency, high fairness, and a high latency achievement rate. The evaluation formula may also be expressed by weighted transmission efficiency, latency, fairness between terminals, and latency achievement rate.

[0029] If base station 40 is operated under a policy that aims to maximize system throughput, the evaluation method is throughput. The throughput evaluation value is the sum of the expected user throughput (i.e., expected system throughput) when wireless communication is performed according to the allocation result. The expected system throughput is the throughput when the signal is transmitted according to the allocation result and the signal is not misdirected. In this case, the larger the evaluation value, the higher the evaluation of the allocation result.

[0030] If base station 40 is operated under a policy to reduce average latency, the evaluation method is average latency. The evaluation value for average latency is the average of the latency times for each user when transmitting signals according to the allocation result. In this case, the smaller the evaluation value, the higher the evaluation of the allocation result. If the evaluation value includes both negative and positive values, the larger the negative value, the higher the evaluation of the allocation result.

[0031] If base station 40 is operated under a policy that emphasizes instantaneous fairness, the evaluation method is fairness. The fairness evaluation value is the variation (dispersion) of throughput among users when signals are transmitted according to the allocation results. In this case, the smaller the evaluation value, the higher the evaluation of the allocation results.

[0032] If base station 40 is operated under a policy that aims for a high delay achievement rate, the evaluation method is the delay achievement rate. For the physical layer, the evaluation value of the delay achievement rate is expressed as <number of received packets that arrived within the requested delay time> / <total number of received packets>, and the higher the evaluation value (maximum 1), the higher the evaluation of the allocation result. For the transport layer, the evaluation value of the delay achievement rate may also be expressed as <number of transport blocks (TB) generated by the base station that arrived within the requested delay time> / total number of TB generated by the base station. Furthermore, for the application layer, the evaluation value of the delay achievement rate may be expressed in terms of the number of data units that arrived within the requested delay time.

[0033] The allocation determination device 50 needs to transmit allocation information to the control device 44 within a fixed time after receiving an allocation request. It is difficult to always determine the optimal allocation result within a short fixed time (e.g., less than 1 ms).

[0034] The allocation results used by base stations must satisfy the constraints stipulated by the communication standard. For example, in the 5G system, there is a constraint that multiple terminals cannot use the same resource at the same time. In addition, in the 5G system, there may be a constraint that the resources allocated to a single terminal may be discontinuous on the frequency axis, but must be continuous on the time axis.

[0035] Generally, obtaining a highly-rated assignment result requires a large amount of computation and a long computation time. Therefore, when the assignment determination device 50 attempts to obtain a highly-rated assignment result, there is a possibility that it may not be able to obtain an assignment result that satisfies the constraints within the fixed time. On the other hand, a low-rated assignment result is likely to be obtained quickly with less computation. However, if communication is performed according to a low-rated assignment result, the transmission efficiency may be low or the delay time may be long.

[0036] Therefore, the assignment determination device 50 includes two assignment determination units (a first assignment determination unit 52 and a second assignment determination unit 54). The first assignment determination unit 52 and the second assignment determination unit 54 perform different assignment determination processes. The first assignment determination unit 52 determines a first assignment result. The second assignment determination unit 54 determines a second assignment result. The degree of evaluation of the first assignment result differs from the degree of evaluation of the second assignment result. The probability that the first assignment result satisfies the constraints differs from the probability that the second assignment result satisfies the constraints. For example, the first assignment result may have a high evaluation but a low probability of satisfying the constraints. The second assignment result may have a low evaluation but a high probability of satisfying the constraints. The first assignment determination unit 52 and the second assignment determination unit 54 may be implemented as separate devices or may be implemented in the same device.

[0037] To obtain a highly rated assignment result, the search range of the assignment result in the first assignment determination unit 52 needs to be wide. Therefore, the computation time for determining the first assignment result will be long. The first assignment determination unit 52 may perform a brute-force search of all possible combinations of assignment results. The first assignment determination unit 52 may use machine learning to determine the assignment result. The first assignment determination unit 52 may use quantum computing or the like to determine the assignment result.

[0038] The second allocation determination unit 54 sequentially allocates resources to each terminal 20 one by one. In this case, there is no combination problem, so the allocation is made while satisfying some constraints. However, if a terminal that is allocated resources first is allocated resources that result in a high evaluation, the terminals that are allocated resources later have no choice and can only be allocated resources that result in a low evaluation. Therefore, the overall evaluation of the allocation results for terminals 20 may be low. The order in which the second allocation determination unit 54 allocates resources to terminals 20 may be determined based on the order of the identification information of the terminals 20, the amount of past transmitted data, channel usage status, delay requests, the amount of transmitted data in the buffer, etc.

[0039] The control device 44 obtains first assignment information from the first assignment determination unit 52 and second assignment information from the second assignment determination unit 54, and determines whether the first assignment information and the second assignment information satisfy the constraints. The control device 44 selects either the first assignment information or the second assignment information that satisfies the constraints. If both the first assignment information and the second assignment information satisfy the constraints, the control device 44 selects either the first assignment information or the second assignment information with the higher evaluation.

[0040] The control device 44 executes the assignment process using the selected assignment result. The control device 44 causes the terminal 20 and the communication device 42 to send and receive modulated signals according to the assignment process result.

[0041] Figure 2 is a diagram illustrating an example of a control device 44. The control device 44 includes a CPU 60, storage 62, memory 64, and a server I / F unit 70. The storage 62 stores applications executed by the CPU 60. An example of an application is a resource allocation program 74. Examples of storage 62 include hard disks and SSDs. The CPU 60 reads applications from the storage 62, writes applications to memory 64, and executes applications stored in memory 64. Examples of memory 64 include DRAM and SRAM. The CPU 60 functions as a resource allocation module 72 by executing the resource allocation program 74. The server I / F unit 70 communicates with the allocation determination device 50. The control device 44 may be composed of circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0042] Figure 3 is a diagram illustrating an example of a first assignment determination unit 52 and a second assignment determination unit 54. Each of the first assignment determination unit 52 and the second assignment determination unit 54 includes a CPU 80, storage 82, memory 84, and a base station I / F unit 86. The storage 82 stores the application that the CPU 80 executes. An example of the application is the assignment determination program 90. Examples of storage 82 include a hard disk and an SSD. The CPU 80 reads the application from the storage 82, writes the application to the memory 84, and executes the application stored in the memory 84. Examples of memory 84 include DRAM and SRAM. The CPU 80 functions as an assignment determination module 88 by executing the assignment determination program 90. The base station I / F unit 86 communicates with the control device 44. The first assignment determination unit 52 and the second assignment determination unit 54 may be configured by circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0043] Figure 4 is a diagram illustrating an example of the frame structure of a modulated signal in the 5G system.

[0044] The 5G system defines frames with a predetermined time length. The time length of a frame is 10 milliseconds. One frame contains 10 subframes, each with a predetermined time length. The time length of a subframe is 1 millisecond.

[0045] The 5G system defines five subcarrier intervals: 15kHz (μ=0), 30kHz (μ=1), 60kHz (μ=2), 120kHz (μ=3), and 240kHz (μ=5). μ is a value that identifies the subcarrier interval.

[0046] The 5G system defines a unit called a slot. A slot consists of 14 OFDM symbols. The duration of an OFDM symbol varies depending on the subcarrier interval. Therefore, the duration of a slot varies depending on the subcarrier interval.

[0047] Each subframe contains at least one slot. When the subcarrier interval is set to 15 kHz, each subframe contains one slot. When the subcarrier interval is set to 30 kHz, each subframe contains two slots. When the subcarrier interval is set to 60 kHz, each subframe contains four slots. When the subcarrier interval is set to 120 kHz, each subframe contains eight slots. When the subcarrier interval is set to 240 kHz, each subframe contains sixteen slots.

[0048] The narrower the subcarrier spacing, the longer the slot time, making it more resistant to multipath interference but resulting in a larger delay. For example, with a subcarrier spacing of 15 kHz, the slot time is 1 ms, which is resistant to multipath interference but results in a larger delay. The wider the subcarrier spacing, the shorter the slot time, resulting in a smaller delay but making it more susceptible to ISI (Inter-Symbol Interference). For example, with a subcarrier spacing of 240 kHz, the slot time is 0.0625 ms, resulting in a smaller delay but making it more susceptible to ISI.

[0049] If terminal 20 is moving at a low speed and is sending and receiving data with a large allowable delay time, the control device 44 may allocate a resource block with a narrow subcarrier spacing to terminal 20. The control device 44 may also allocate resource elements included in the resource block with a narrow subcarrier spacing to terminal 20.

[0050] If terminal 20 is moving at high speed and sending and receiving data with a short allowable delay time, the control device 44 may allocate a resource block with a wide subcarrier spacing to terminal 20. The control device 44 may also allocate resource elements included in the resource block with a wide subcarrier spacing to terminal 20.

[0051] This allows 5G to use a wider range of subcarriers compared to 4G, resulting in shorter loading times.

[0052] Figure 5 illustrates a first example of resource block RB configuration. Resource block RB consists of one slot (14 OFDM symbols) in the time direction and a predetermined number of subcarriers (e.g., 12) in the frequency direction.

[0053] In 5G modulation signals, multiple resource blocks (RBs) are combined into a single resource block group. For example, in a 5G modulation signal using a 100MHz bandwidth, one subframe contains 17 resource block groups.

[0054] For example, if a subframe contains 16 resource blocks, each of the 16 resource blocks consists of one slot (14 OFDM symbols) and 192 (12 x 16) subcarriers.

[0055] As shown in Figure 5, the control device 44 may assign the widest subcarrier interval of 15 kHz (μ=0) to the subcarrier interval of resource blocks in all regions of the bandwidth. In this case, the control device 44 can send and receive data with a large allowable delay time but strong resistance to multipath for all of the assigned terminals 20.

[0056] Figure 6 is a diagram illustrating a second example of resource block arrangement. As shown in Figure 6, the control device 44 may allocate the narrowest subcarrier interval of 240 kHz (μ=4) to the subcarrier interval of resource blocks in all regions of the bandwidth. In this case, the control device 44 can send and receive data with a short allowable delay time to all of at least one terminal 20.

[0057] Figure 7 is a diagram illustrating a third example of resource block arrangement. As shown in Figure 7, the control device 44 may divide the bandwidth into two regions, assign the widest subcarrier interval of 15 kHz (μ=0) to the resource blocks in one region, and assign a subcarrier interval of 60 kHz (μ=2) to the resource blocks in the other region. In this case, the control device 44 can send and receive data with a mix of terminals 20 that send and receive data requiring high quality but with a large allowable delay time, and terminals 20 that send and receive data requiring short allowable delay time but with low allowable delay time, all within the same subframe.

[0058] The control device 44 can divide the bandwidth into multiple regions in this way and assign different subcarrier intervals to the subcarrier intervals of each resource block in each of the multiple regions. As a result, the control device 44 can assign resource blocks with appropriate subcarrier intervals to the terminals 20, and thus satisfy the requests of each of the assigned terminals 20.

[0059] Figure 8 illustrates an example of resource block configuration and mini-slot allocation.

[0060] A single resource block may contain, for example, 14 OFDM symbols in the time direction and 12 subcarriers in the frequency direction. A single resource block may contain 168 resource elements (12 x 14). Each of the 168 resource elements can be identified by its subcarrier position and symbol position.

[0061] In the 5G system, a unit called a mini-slot is defined. A mini-slot consists of H consecutive OFDM symbols and one subcarrier, where H is an integer greater than or equal to 2, for example, 2, 4, 7, or 14. The control device 44 can allocate any resource element within a resource block to the terminal 20 in units of mini-slots.

[0062] For example, the control device 44 can assign resource elements to terminals in mini-slot units and assign the narrowest subcarrier interval of 240 kHz (μ=4) to the subcarrier interval of resource blocks including the mini-slots, thereby enabling the terminal 20 to which the resource elements are assigned to send and receive data requiring ultra-low latency.

[0063] Figure 9 is a diagram illustrating the timing of the allocation process. Prior to executing the allocation process, the control device 44 selects at least one terminal 20 to be allocated at the first time t1. The second time t2 is a time later than the first time t1. The second time t2 is the time when the allocation process begins, in which communication blocks (resource blocks or resource elements) from the second time t2 onward are allocated to the selected terminal.

[0064] Between the first time t1 and the second time t2, the control device 44 decides which communication block from the second time t2 onward to assign to the terminal that was assigned at the first time t1.

[0065] The control device 44 transmits a first assignment request to the first assignment determination unit 52 and a second assignment request to the second assignment determination unit 54. By the second time t2, it obtains first assignment information from the first assignment determination unit 52 and second assignment information from the second assignment determination unit 54.

[0066] The control device 44 selects either the first allocation information or the second allocation information and starts resource allocation processing based on the selected allocation information at the second time t2. From the third time t3 to the fourth time t4, after the resource allocation processing is completed, the control device 44 causes the terminal 20 and the communication device 42 to send and receive modulated signals according to the allocation processing results. Alternatively, the control device 44 may start the allocation processing before the second time t2 and cause the terminal 20 and the communication device 42 to send and receive modulated signals according to the allocation processing results.

[0067] Figure 10 is a diagram illustrating a first example of setting the first time t1 and the second time t2.

[0068] The first time t1 and the second time t2 are times predetermined by scheduling. When the control device 44 performs allocation processing for a predetermined number of subframes, the first time t1 is a time before the predetermined number of subframes to be allocated. The first time t1 may be the start time of the subframe, or it may be a time shifted by a predetermined amount of time before or after the start time of the subframe. When the control device 44 performs allocation processing for a predetermined number of subframes, the second time t2 may be the start time of the predetermined number of subframes to be allocated, or it may be a time before the start time of the predetermined number of subframes to be allocated. The control device 44 may also perform allocation processing for each slot. In that case, the difference between the first time t1 and the second time t2 is 1 slot.

[0069] The first time t1 and the second time t2 may be asynchronous times with respect to the subframe. For example, the first time t1 and the second time t2 may be times set when a predetermined event occurs. The control device 44 may determine that the first time t1 is the time when a predetermined amount of downlink data has been accumulated in the communication device 42, or when a predetermined amount of reservation requests for transmission and reception assignments have been accumulated.

[0070] If the time at which a predetermined event occurs is set as the first time t1, the control device 44 may set the second time t2 to a time predetermined time after the first time t1. If the time at which a predetermined event occurs is set as the first time t1, the control device 44 may set the second time t2 to the start time of the subframe immediately following the first time t1, or a time predetermined time before the start time of the subframe immediately following the first time t1.

[0071] Figure 11 is a diagram illustrating a second example of setting the first time t1 and the second time t2.

[0072] The control device 44 can allocate resource elements to the data transmission and reception terminal 20 in units of mini-slots. In this case, the control device 44 may set the difference between the first time t1 and the second time t2 to the minimum time length of the OFDM symbol. The minimum time length of the OFDM symbol is the time length of the OFDM symbol when the subcarrier spacing is narrowest at 240 kHz (μ=4).

[0073] The control device 44 may change the difference between the first time t1 and the second time t2. The control device 44 may determine the second time t2 according to the allowable delay time of the data transmitted and received by the assigned terminal. For example, the control device 44 may shorten the difference between the first time t1 and the second time t2 as the allowable delay time decreases. This allows the control device 44 to transmit and receive data at an earlier time for data with a shorter allowable delay time.

[0074] Figures 12 and 13 are flowcharts illustrating an example of the processing performed by the control device 44.

[0075] The control device 44 determines a first time t1 and a second time t2 (S102). The first time t1 is the time to start the resource allocation decision process. The first time t1 may be a time that has been scheduled in advance. The first time t1 may be the time when a predetermined event occurs that triggers resource allocation. The second time t2 is the timing to start the allocation process based on the allocation result determined by the resource allocation decision process.

[0076] The control device 44 determines whether the current time is the first time t1 (S104).

[0077] If the current time is not the first time t1 (S104: NO), the control device 44 executes the determination process of S104 again.

[0078] If the current time is the first time t1 (S104: YES), the control device 44 selects at least one terminal 20 to be assigned at the first time t1 (S106). The terminal 20 to be assigned at the first time t1 may be all of the at least one terminal 20 wirelessly connected to the base station 40, or it may be a part of at least one terminal 20.

[0079] Here are some examples of selections for the allocation targets.

[0080] If the maximum number of assignable terminals 20 in a single assignment process is predetermined, the control device 44 may select at least one terminal 20 as the target for assignment, provided that the number does not exceed the maximum number.

[0081] If downlink data is stored in the communication device 42 at the first time step t1, the control device 44 may prioritize selecting the terminal 20 to which the downlink data stored in the communication device 42 is to be sent as the target for allocation.

[0082] If a resource allocation reservation request is stored in the communication device 42 at the first time step t1, the control device 44 may prioritize selecting the terminal 20 that sent the reservation request stored in the communication device 42 as the allocation target.

[0083] If, at the first time step t1, downlink data with an allowable delay time less than or equal to a predetermined time is stored in the communication device 42, the control device 44 may prioritize selecting terminal 20 as the destination for the downlink data with an allowable delay time less than or equal to a predetermined time as the target for allocation.

[0084] If, at the first time step t1, a reservation request for resource allocation for sending and receiving data with an allowable delay time of less than or equal to a predetermined time is stored in the communication device 42, the control device 44 may prioritize selecting terminal 20, which sends and receives data with an allowable delay time of less than or equal to a predetermined time, as the allocation target.

[0085] The control device 44 determines the allocation range in the modulated signal (S108). The allocation range is a range consisting of a predetermined number of subcarriers and a predetermined number of OFDM symbols at a time after the second time t2. When the allocation process is performed for each predetermined number of subframes, the control device 44 may set the allocation range to a range consisting of all subcarriers included in the modulated signal and a predetermined number of OFDM symbols included in subframes after the second time t2.

[0086] The allocation range may be changed for each allocation process. The control device 44 may change the allocation range according to the number of terminals 20 to be allocated. If the allocation targets include terminals 20 that send and receive data with an allowable delay time of less than or equal to a predetermined time, the control device 44 may set the allocation range to include the first number of OFDM symbols immediately after the second time t2. If the allocation targets do not include terminals 20 that send and receive data with an allowable delay time of less than or equal to a predetermined time, the control device 44 may set the allocation range to include the second number of OFDM symbols that is greater than the first number immediately after the second time t2. This allows the control device 44 to send and receive data with an allowable delay time of less than or equal to a predetermined time at an earlier time.

[0087] The control device 44 obtains identification information of the communication block already assigned to the terminal 20 that sends and receives data included in the assignment range (S110). If a resource block or resource element is selected as the communication block, the control device 44 obtains identification information of the resource block already assigned to the terminal 20 that sends and receives data included in the assignment range and identification information of the assigned resource element.

[0088] The control device 44 determines at least one communication block, excluding already allocated communication blocks within the allocation range, as an assignable communication block (S112). If a resource block or resource element is selected as a communication block, the control device 44 determines at least one resource block, excluding already allocated resource blocks within the allocation range, as an assignable resource block, and determines at least one resource element, excluding already allocated resource elements within the allocation range, as an assignable resource element.

[0089] The control device 44 obtains reference information regarding the assigned terminal 20 (S114).

[0090] The reference information may include the allowable delay time for data transmitted and received by terminal 20. The reference information may also include the communication quality of data previously transmitted and received by terminal 20. Information regarding the data communication quality includes CQI (Channel Quality Indicator), MCS (Modulation and Coding Scheme), transmission power, and error rate for terminal 20. CQI is an index value indicating the reception quality of terminal 20. MCS is information representing the quadrature modulation scheme and coding rate. CQI, MCS, transmission power, and error rate may be average values ​​from the past or values ​​from the most recent time period.

[0091] The reference information may include information regarding the amount of data transmitted by terminal 20. This information may include the amount of untransmitted data transmitted by terminal 20, the amount of data per unit time transmitted and received by terminal 20 in the past, the frequency of data transmitted and received by terminal 20 in the past, the trend of data transmitted and received by terminal 20 in the past, the predicted frequency of data to be transmitted and received by terminal 20 in the future, and the predicted trend of data to be transmitted and received by terminal 20 in the future. In Massive MIMO wireless communication, the reference information may also include the propagation channel matrix previously used by terminal 20.

[0092] The control device 44 generates a first allocation request and a second allocation request, outputs the first allocation request to the first allocation determination unit 52, and outputs the second allocation request to the second allocation determination unit 54 (S116). Each of the first and second allocation requests includes identification information of the allocation target terminal 20, reference information relating to the allocation target terminal 20, and information indicating the second time t2. Each of the first and second allocation requests may also include identification information of at least one allocationable communication block. The identification information of at least one allocationable communication block includes information that identifies the position in the frequency direction and the position in the time direction for at least one allocationable resource block, and information that identifies the position in the frequency direction and the position in the time direction for at least one allocationable resource element.

[0093] When the first allocation determination unit 52 receives a first allocation request from the control device 44, it determines the first allocation result and outputs first allocation information representing the first allocation result to the control device 44. When the second allocation determination unit 54 receives a second allocation request from the control device 44, it determines the second allocation result and outputs second allocation information representing the second allocation result to the control device 44.

[0094] If the first allocation determination unit 52 cannot obtain the first allocation result by the second time t2, it outputs allocation unavailable information to the control device 44 at the second time t2. If the second allocation determination unit 54 cannot obtain the second allocation result by the second time t2, it outputs allocation unavailable information to the control device 44 at the second time t2.

[0095] The first allocation information and the second allocation information each indicate which resource element among the at least one resource element within the allocation range the allocated terminal 20 will use to send and receive data.

[0096] The first and second allocation information may further indicate the subcarrier spacing for at least one resource block within the allocation range. The first and second allocation information may further indicate the orthogonal modulation scheme, transmit power, and coding rate of the data contained in at least one communication block. The first and second allocation information may further indicate the propagation channel matrix used by the allocated terminal 20 in the Massive MIMO scheme.

[0097] When the first allocation determination unit 52 receives a first allocation request transmitted from the control device 44, it generates first allocation information based on the identification information of the allocation target terminal 20, the identification information of at least one allocationable communication block, and the reference information of the allocation target terminal. When the second allocation determination unit 54 receives a second allocation request transmitted from the control device 44, it generates second allocation information based on the identification information of the allocation target terminal 20, the identification information of at least one allocationable communication block, and the reference information of the allocation target terminal.

[0098] The first assignment determination unit 52 outputs the first assignment information to the control device 44 by the time the control device 44 can execute the assignment process at the second time t2. That is, the first assignment determination unit 52 outputs the first assignment information to the control device 44 at a time before the second time t2. The second assignment determination unit 54 outputs the second assignment information to the control device 44 by the time the control device 44 can execute the assignment process at the second time t2. That is, the second assignment determination unit 54 outputs the second assignment information to the control device 44 at a time before the second time t2.

[0099] The first assignment determination unit 52 and the second assignment determination unit 54 may use a machine learning model to generate first assignment information and second assignment information based on the identification information of the terminal to be assigned 20, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned. The first assignment determination unit 52 and the second assignment determination unit 54 may use a solver for the QUBO (Quadratic Unconstrained Binary Optimization) problem to generate first assignment information and second assignment information. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 may generate an objective function for the QUBO problem based on the identification information of the terminal to be assigned 20, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned, provide the generated objective function to the QUBO solver, obtain an assignment result that minimizes the objective function from the QUBO solver, and generate assignment information based on the obtained assignment result.

[0100] The first assignment determination unit 52 and the second assignment determination unit 54 can change the calculation time from the input of an assignment request to the output of assignment information. When the first assignment determination unit 52 and the second assignment determination unit 54 receive the first assignment request and the second assignment information, they set the calculation time based on the second time t2 included in the first assignment request and the second assignment information, so that the first assignment information and the second assignment information can be reliably generated by the second time t2.

[0101] For example, the first assignment determination unit 52 and the second assignment determination unit 54 may include multiple machine learning models with different computation times. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 may select a machine learning model from the multiple machine learning models that can output assignment information by the second time step t2, and generate the assignment information using the selected machine learning model. The first assignment determination unit 52 and the second assignment determination unit 54 may use a QUBO solver with a configurable computation time. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 set the parameters related to the computation time in the QUBO solver so that assignment information can be output by the second time step t2.

[0102] The control device 44 acquires the first assignment information from the first assignment determination unit 52 and the second assignment information from the second assignment determination unit 54 (S118).

[0103] The control device 44 determines whether the current time is the second time t2 (S120).

[0104] If the current time is not the second time t2 (S120: NO), the control device 44 executes the determination process of S120 again.

[0105] If the current time is the second time t2 (S120: YES), the control device 44 determines whether the first assignment information and the second assignment information satisfy the constraints (S122).

[0106] If the first assignment information and the second assignment information satisfy the constraints (S122: YES), the control device 44 selects the one with the higher evaluation from the first assignment information and the second assignment information as the assignment information (S124).

[0107] If at least one of the first assignment information and the second assignment information does not satisfy the constraint (S122: NO), the control device 44 determines whether the first assignment information or the second assignment information satisfies the constraint (S126).

[0108] If the first assignment information or the second assignment information satisfies the constraint (S126: YES), the control device 44 selects the first assignment information or the second assignment information that satisfies the constraint as the assignment information (S128).

[0109] If the first and second assignment information does not satisfy the constraints (S126: NO), the control device 44 terminates the process.

[0110] The control device 44 performs an assignment process based on the assignment information selected in S124 or S128 (S130). After this, the control device 44 causes at least one terminal 20 and the communication device 42 to send and receive modulated signals according to the assignment process.

[0111] As a result of the above processing, the communication device 42 can send and receive data with the terminal 20 assigned in the assignment process within the assigned range.

[0112] Figure 14 is a diagram illustrating an example of the format for describing allocation information.

[0113] The allocation information indicates which communication block, such as a resource block group, within the allocation range will be used by the allocated terminal 20 to send or receive data. A portion of at least one resource block group within the allocation range may not be allocated to any of the terminals 20.

[0114] An example of allocation information is represented by a matrix of boxes arranged to represent at least one communication block within the allocation range. The position of one of the boxes in the row or column direction is identified by the position of the subcarrier. The position of the other box in the row or column direction is identified by the position of the OFDM symbol. Figure 14 shows the description format when (12 subcarriers × 16) × 14 OFDM constitutes one resource block group, and 17 resource block groups constitute the allocation range.

[0115] This type of assignment information is the solution to the problem of determining which of the assigned terminals 20 should be associated with each of the multiple boxes.

[0116] The first assignment determination unit 52 and the second assignment determination unit 54 can obtain assignment information by pre-training a machine learning model such as a neural network. For example, the designer of the first assignment determination unit 52 and the second assignment determination unit 54 creates a neural network that outputs assignment information when given input information including identification information of the terminal to be assigned 20, identification information of at least one assignable communication block, and reference information of the terminal to be assigned. The designer trains the created neural network based on training data including past input information and ideal solutions. The first assignment determination unit 52 and the second assignment determination unit 54 can use the machine learning model thus created to generate assignment information based on the identification information of the terminal to be assigned 20, identification information of at least one assignable communication block, and reference information of the terminal to be assigned.

[0117] The first assignment determination unit 52 and the second assignment determination unit 54 can also generate assignment information by solving the QUBO problem, which has a quadratic function containing multiple binary variables as its objective function. In this case, the quadratic function, which is the objective function, contains at least one binary variable that corresponds one-to-one with each assigned terminal 20, in a number corresponding to the number of boxes that make up the matrix. Furthermore, the quadratic function may also contain binary variables that represent constraints.

[0118] The designers of the first assignment determination unit 52 and the second assignment determination unit 54 create a quadratic function whose minimized solution yields assignment information closer to pre-set conditions, based on the identification information of the terminal to be assigned, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned. The designers of the first assignment determination unit 52 and the second assignment determination unit 54 create a formalization algorithm that generates such a quadratic function, based on the identification information of the terminal to be assigned, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned.

[0119] The first assignment determination unit 52 and the second assignment determination unit 54 use the formulated algorithm thus created to generate a quadratic function, which is the objective function, based on the identification information of the terminal to be assigned, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned. The first assignment determination unit 52 and the second assignment determination unit 54 provide the generated quadratic function to the QUBO solver to calculate the solution to the quadratic function. The first assignment determination unit 52 and the second assignment determination unit 54 generate assignment information based on the solution to the quadratic function calculated by the QUBO solver.

[0120] The first assignment determination unit 52 and the second assignment determination unit 54 may, for example, determine an assignment order for the terminals to be assigned and generate assignment information by associating the terminals with a plurality of boxes arranged in a matrix according to the determined order. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 may rank the terminals in order of the smallest amount of data to be transmitted and received, in order of the shortest allowable delay time, or in order of the smallest amount of data transmitted and received in the past.

[0121] The format of the first assignment information generated by the first assignment determination unit 52 and the second assignment information generated by the second assignment determination unit 54 are identical. Figure 15 is a diagram illustrating an example of the format of the first assignment information generated by the first assignment determination unit 52 or the second assignment information generated by the second assignment determination unit 54. "A" to "H" shown in Figure 15 are information that identifies the user of the terminal 20 to which the resource element has been assigned.

[0122] The reference information may include the allowable delay time for transmitted and received data at the assigned terminal 20. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 use a machine learning model or formulation algorithm to generate the first and second assignment information so as to assign terminals with shorter allowable delay times to resource elements that complete transmission and reception earlier than terminals with longer allowable delay times. Specifically, the first and second assignment determination units 52 and 54 use a machine learning model or formulation algorithm to generate the first and second assignment information so as to assign terminals with shorter allowable delay times to resource elements of OFDM symbols that are earlier in time than terminals with longer allowable delay times. For example, suppose the reference information indicates that user A's terminal 20 has a shorter allowable delay time for transmitted and received data than user D's terminal 20. In this case, by using a machine learning model or formulation algorithm, the first and second assignment determination units 52 and 54 can assign user A's terminal 20 a resource block that is earlier in time than the resource block assigned to user D's terminal 20, as shown in Figure 15.

[0123] The first allocation determination unit 52 and the second allocation determination unit 54 may use a machine learning model or a formalized algorithm to generate allocation information so that there are many terminals that can communicate wirelessly within the allowable delay time.

[0124] The reference information may include the amount of data per unit time of data previously transmitted and received by the assigned terminals, or the amount of data per unit time predicted for the future. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 may use a machine learning model or formulation algorithm to generate the assignment information so that the number of terminals that satisfy the amount of data transmitted and received per unit time is large. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 may also use a machine learning model or formulation algorithm to generate the assignment information so that the amount of data transmitted and received per unit time is satisfied for terminals whose amount of data per unit time of data previously transmitted and received or the amount of data per unit time predicted for the future exceeds a threshold. The first assignment determination unit 52 and the second assignment determination unit 54 may also use a machine learning model or formulation algorithm to generate the assignment information so that the amount of data transmitted and received per unit time is maximized for all terminals.

[0125] The reference information may include the communication quality of data previously transmitted and received by the assigned terminal. In this case, the first assignment determination unit 52 and the second assignment determination unit 54 may use a machine learning model or a formalization algorithm to generate the assignment information so as to assign a higher coding rate or a higher quadrature modulation scheme to terminals with high communication quality of data previously transmitted and received, compared to terminals with low communication quality.

[0126] Specifically, the first allocation determination unit 52 and the second allocation determination unit 54 use a machine learning model or formulation algorithm to generate allocation information so as to allocate resource elements contained in resource blocks with wider subcarrier spacing than resource blocks allocated to terminals with lower communication quality to terminals with higher communication quality data transmitted and received in the past. For example, suppose the reference information indicates that user C's terminal 20 has higher communication quality than user B's terminal 20. In this case, by using a machine learning model or formulation algorithm, the first allocation determination unit 52 and the second allocation determination unit 54 can allocate more subcarriers to user C's terminal 20 than the number of subcarriers allocated to user B's terminal 20, as shown in Figure 15.

[0127] Figure 16 is a diagram illustrating an example of the first assignment determination unit 52 and the second assignment determination unit 54. The first assignment determination unit 52 and the second assignment determination unit 54 generate assignment information using a machine learning model.

[0128] The first allocation determination unit 52 and the second allocation determination unit 54 each include a request acquisition unit 102, a determination unit 104, and a setting unit 106.

[0129] The request acquisition unit 102 acquires a first allocation request and a second allocation request (simply referred to as allocation requests) from the control device 44. The first allocation information and the second allocation information are also simply referred to as allocation information. The request acquisition unit 102 outputs to the determination unit 104 the identification information of the terminal to be allocated, the identification information of at least one allocationable communication block (at least one allocationable resource block and / or at least one allocationable resource element) included in the allocation request, and the reference information of the terminal to be allocated. The request acquisition unit 102 outputs to the setting unit 106 the second time t2 included in the allocation request.

[0130] The decision unit 104 includes a first machine learning model 104-1, a second machine learning model 104-2, ..., an nth machine learning model 104-n, where n is an integer greater than or equal to 2. The multiple machine learning models 104-1 to 104-n take as input the identification information of the terminal to be assigned, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned, and output assignment information. Each of the multiple machine learning models is, for example, a pre-trained neural network.

[0131] Each of the multiple machine learning models 104-1 to 104-n has a different computation time from inputting an allocation request to outputting allocation information. Each of the multiple machine learning models 104-1 to 104-n has a different internal computational structure and computational algorithm. For example, if each of the multiple machine learning models 104-1 to 104-n is a neural network, then each of the multiple machine learning models 104-1 to 104-n has a different number of layers and nodes. Therefore, each of the multiple machine learning models 104-1 to 104-n has a different accuracy in the actual output allocation information compared to the ideal allocation information that should be obtained for the input allocation request.

[0132] For example, the first machine learning model 104-1 has the fastest computation speed but the lowest accuracy. The nth machine learning model 104-n has the highest accuracy but the slowest computation speed. From the second machine learning model 104-2 onwards, the (n-1)th machine learning models have progressively slower computation speeds and progressively higher accuracy.

[0133] Such a decision unit 104 returns assignment information to the control device 44 from one of the multiple machine learning models 104-1 to 104-n.

[0134] When the setting unit 106 receives an allocation request, it selects the machine learning model from among the multiple machine learning models 104-1 to 104-n of the first allocation determination unit 52 that has the highest accuracy and can transmit allocation information by the reply time when the control device 44 can execute the allocation process by the second time t2. When the setting unit 106 receives an allocation request, it selects the machine learning model from among the multiple machine learning models 104-1 to 104-n of the second allocation determination unit 54 that has the fastest calculation speed and can transmit allocation information by the reply time when the control device 44 can execute the allocation process by the second time t2. The setting unit 106 causes the determination unit 104 to generate allocation information using the selected machine learning model.

[0135] Figure 17 is a diagram illustrating another example of the first assignment determination unit 52 and the second assignment determination unit 54. The first assignment determination unit 52 and the second assignment determination unit 54 generate assignment information by solving the QUBO problem.

[0136] The first assignment determination unit 52 and the second assignment determination unit 54 each include a request acquisition unit 102, a formulation unit 112, a solution calculation unit 114, an output unit 116, and a setting unit 106.

[0137] The request acquisition unit 102 acquires an allocation request from the control device 44. The request acquisition unit 102 outputs to the formulation unit 112 the identification information of the terminal to be allocated, the identification information of at least one allocationable communication block (at least one allocationable resource block and / or at least one allocationable resource element) included in the allocation request, and the reference information of the terminal to be allocated. The request acquisition unit 102 outputs to the setting unit 106 the second time t2 included in the allocation request.

[0138] The formulation unit 112 generates an objective function for the QUBO problem according to a formulation algorithm pre-generated by the designer, based on the identification information of the terminal to be assigned, the identification information of at least one assignable communication block, and the reference information of the terminal to be assigned. The QUBO problem is a quadratic function containing multiple binary variables. Each of at least some of the multiple binary variables corresponds to at least one resource element and one of the terminals to be assigned, indicating whether the corresponding terminal is assigned to the corresponding resource element. In other words, at least some of the multiple binary variables represent assignment information. The formulation unit 112 outputs the generated objective function to the solution calculation unit 114.

[0139] The solution calculation unit 114 receives the objective function generated by the formulation unit 112 as input and calculates the solution to the QUBO problem using the solution calculation unit 118. The solution calculation unit 118 is an example of a QUBO solver and calculates a solution that minimizes the objective function. The solution calculation unit 118 may be provided in the first assignment determination unit 52 and the second assignment determination unit 54, or it may be provided outside the first assignment determination unit 52 and the second assignment determination unit 54.

[0140] The solution-finding unit 118 is a device whose computation time from inputting the objective function to outputting the solution can be changed by changing the parameter settings. For example, the solution-finding unit 118 may be a device in which the probability of outputting an approximate solution close to the optimal solution increases as the computation time is set to be longer, and the probability of outputting an approximate solution farther from the optimal solution increases as the computation time is set to be shorter.

[0141] The problem-solving unit 118 is, for example, a device that uses the Simulated Bifurcation (SB) algorithm. The problem-solving unit 118 using the SB algorithm can change the time it takes to output a solution by changing a parameter that represents the completion time.

[0142] The output unit 116 obtains the solution to the QUBO problem from the solution calculation unit 114. The output unit 116 generates assignment information based on the solution to the QUBO problem. More specifically, the output unit 116 obtains the solutions for multiple binary variables included in the objective function and generates assignment information. The output unit 116 returns the generated assignment information to the control device 44.

[0143] When the setting unit 106 receives an assignment request, it sets parameters related to the calculation time in the solving unit 118 based on the second time t2. More specifically, the setting unit 106 sets the calculation time of the solving unit 118 so that it transmits the assignment information by the reply time when the control device 44 can execute the assignment process by the second time t2. For example, when the setting unit 106 of the first assignment determination unit 52 receives an assignment request, it sets the calculation time of the solving unit 118 so that it outputs the longest but most accurate assignment information within the range where the assignment information can be output by the reply time. For example, if the solving unit 118 uses the SB algorithm, the setting unit 106 sets a parameter representing the end time. When the setting unit 106 of the second assignment determination unit 54 receives an assignment request, it sets the calculation time of the solving unit 118 so that it outputs the shortest but least accurate assignment information within the range where the assignment information can be output by the reply time. For example, if the solving unit 118 uses the SB algorithm, the setting unit 106 sets a parameter representing the end time.

[0144] The following describes a modified version of the communication system related to the arrangement of the allocation determination device 50.

[0145] Figure 18 is a diagram illustrating an example of a communication system 10a according to the first modified example. The communication system 10a includes base stations 40a and 40b. Terminal 20a is connected to base station 40a. Terminal 20b is connected to base station 40b. An allocation determination device 202 is connected to base stations 40a and 40b. The allocation determination device 202 corresponds to the allocation determination device (MEC server) 50 shown in Figure 1.

[0146] The allocation determination device 202 receives allocation requests from multiple base stations 40a and 40b. In response to receiving an allocation request, the allocation determination device 202 generates allocation information and sends the generated allocation information back to the base stations 40a and 40b that sent the allocation request.

[0147] Figure 19 is a diagram illustrating an example of a communication system 10b according to a second modified example. The communication system 10b includes base stations 40a, 40b, and 40c. Terminal 20a is connected to base station 40a. Terminal 20b is connected to base station 40b. Terminal 20c is connected to base station 40c. An allocation determination device 204 is connected to the core network 30. The allocation determination device 204 corresponds to the allocation determination device 50 shown in Figure 1. The allocation determination device 204 is also referred to as a remote server.

[0148] The allocation determination device 204 receives allocation requests from multiple base stations 40a, 40b, and 40c via the core network 30. In response to receiving an allocation request, the allocation determination device 204 generates allocation information and sends the generated allocation information back to the base stations 40a, 40b, and 40c that sent the allocation request via the core network 30.

[0149] Figure 20 is a diagram illustrating an example of a communication system 10c according to the third modified example. The communication system 10c includes a relay device 206. The relay device 206 relays the transmission and reception of information between the base station 40 and the core network 30. An allocation decision device 208 is connected to the relay device 206. The allocation decision device 208 corresponds to the allocation decision device 50 shown in Figure 1. The relay device 206 relays the transmission and reception of information between the base station 40 and the allocation decision device 208. The relay device 206 obtains from the core network 30 some of the reference information of the terminals to be allocated, which is necessary to generate allocation information. The base station 40 outputs an allocation request to the allocation decision device 208 via the relay device 206. Upon receiving the allocation request, the relay device 206 obtains some of the information to be included in the reference information of the terminals to be allocated from the core network 30, includes the obtained information in the allocation request, and forwards it to the allocation decision device 208. The allocation determination device 208 generates allocation information in response to receiving an allocation request and sends the generated allocation information back to the base station 40 via the relay device 206.

[0150] Figure 21 is a diagram illustrating an example of a communication system 10d according to the fourth modified example. The communication system 10d includes a relay device 212. The relay device 212 relays the transmission and reception of information between each of the base stations 40a and 40b and the allocation decision device 214. Base station 40a is connected to terminal 20a. Base station 40b is connected to terminal 20b. Each of the base stations 40a and 40b outputs an allocation request to the allocation decision device 214 via the relay device 212. The allocation decision device 214 generates allocation information in response to receiving an allocation request and returns the generated allocation information to the base stations 40a and 40b that output the allocation request via the relay device 212.

[0151] Figure 22 is a diagram illustrating an example of a communication system 10e according to the fifth modified example. The communication system 10e includes a plurality of relay devices 212a, 212b. The communication system 10e includes a plurality of allocation determination devices 214a, 214b that correspond one-to-one with the plurality of relay devices 212a, 212b. Relay device 212a relays the transmission and reception of information between each of the plurality of corresponding base stations 40a, 40b and the corresponding allocation determination device 214a. Relay device 212b relays the transmission and reception of information between each of the plurality of corresponding base stations 40c, 40d and the corresponding allocation determination device 214b. Each of the plurality of base stations 40a, 40b outputs an allocation request to the corresponding allocation determination device 214a via the corresponding relay device 212a. Each of the plurality of base stations 40c, 40d outputs an allocation request to the corresponding allocation determination device 214b via the corresponding relay device 212b. The allocation determination device 214a generates allocation information upon receiving an allocation request and sends the generated allocation information back to the base stations 40a and 40b that output the allocation request via the corresponding relay device 212a. The allocation determination device 214b generates allocation information upon receiving an allocation request and sends the generated allocation information back to the base stations 40c and 40d that output the allocation request via the corresponding relay device 212b.

[0152] Figure 23 is a diagram illustrating a modified configuration of the assignment determination device 50. In Figure 1, an assignment determination device 50 comprising two assignment determination units 52 and 54 was described. Figure 23 shows an assignment determination device 222 comprising three assignment determination units 224, 226, and 228. The first assignment determination unit 224, the second assignment determination unit 226, and the third assignment determination unit 228 perform different assignment determination processes. The first assignment determination unit 224 determines the first assignment result. The second assignment determination unit 226 determines the second assignment result. The third assignment determination unit 228 determines the third assignment result. The degree of evaluation of the first assignment result differs from the degree of evaluation of the second assignment result and the degree of evaluation of the third assignment result. The probability that the first assignment result satisfies the constraints differs from the probability that the second assignment result satisfies the constraints and the probability that the third assignment result satisfies the constraints. For example, the first assignment result has a high evaluation but a low probability of satisfying the constraints. The third assignment result has a low evaluation but a high probability of satisfying the constraints. The first assignment result is moderate in evaluation and moderate in the likelihood of satisfying the constraints. The first assignment determination unit 224, the second assignment determination unit 226, and the third assignment determination unit 228 may be implemented as separate devices or within the same device.

[0153] Figure 24 illustrates another variation of the configuration of the allocation determination device 50. In Figure 1, a common allocation determination device 50 is used for all terminals. Each of the multiple terminals 20 may have different communication requirements. Different communication requirements result in different allocation determination processes by the allocation determination device. For example, the multiple terminals 20 may include terminals that want high-speed, high-capacity communication, terminals that want low-latency communication, and terminals that want to enable many simultaneous connections. The multiple terminals 20 are classified into multiple terminal groups according to their communication requirements. An allocation determination device suitable for each terminal group is used.

[0154] Three allocation decision devices 230, 240, and 250 are connected to the base station 40. Terminals that require high-speed, high-capacity communication are called Enhanced Mobile Broadband (eMBB) terminals. Terminals that require low-latency communication are called Ultra Reliable Low Latency Communication (URLLC) terminals. Terminals that require a large number of simultaneous connections are called Massive Machine Type Communication (mMTC) terminals.

[0155] The first allocation determination device 230 includes a first allocation determination unit 232 and a second allocation determination unit 234. Similar to the allocation determination device 50 shown in Figure 1, the first allocation determination device 230 determines allocation information that satisfies the constraints or has a high evaluation from the first allocation information obtained by the first allocation determination unit 232 and the second allocation information obtained by the second allocation determination unit 234. The first allocation determination unit 232 and the second allocation determination unit 234 perform allocation determination processing in accordance with the allocation policy for eMBB terminals.

[0156] The second allocation determination device 240 includes a first allocation determination unit 242 and a second allocation determination unit 244. Similar to the allocation determination device 50 shown in Figure 1, the second allocation determination device 240 determines allocation information that satisfies the constraints or has a high evaluation from the first allocation information obtained by the first allocation determination unit 242 and the second allocation information obtained by the second allocation determination unit 244. The first allocation determination unit 242 and the second allocation determination unit 244 perform allocation determination processing in accordance with the allocation policy for URLLC terminals.

[0157] The third allocation determination device 250 includes a first allocation determination unit 252 and a second allocation determination unit 254. Similar to the allocation determination device 50 shown in Figure 1, the third allocation determination device 250 determines allocation information that satisfies the constraints or has a high evaluation from the first allocation information obtained by the first allocation determination unit 252 and the second allocation information obtained by the second allocation determination unit 254. The first allocation determination unit 252 and the second allocation determination unit 254 perform allocation determination processing in accordance with the allocation policy for mMTC terminals.

[0158] The control device 44 transmits assignment requests to the first assignment determination device 230, the second assignment determination device 240, and the third assignment determination device 250 in a predetermined order.

[0159] For example, because URLLC terminals have strict latency requirements, it is desirable to allocate resources so that as much data as possible can be transmitted within the latency period or within a single slot. Therefore, the control device 44 may first send an allocation request to the second allocation determination device 240. The control device 44 also notifies the second allocation determination device 240 of the information necessary for resource allocation, such as the amount of data at the terminal, the allowable latency period, and channel information. When the second allocation determination device 240 receives an allocation request from the control device 44, it sends the allocation information back to the control device 44 before the first fixed time elapses.

[0160] An example of a resource allocation policy for URLLC terminals followed by the second allocation decision device 240 is to not allocate the latter 7 symbols of the 14 OFDM symbols that make up one slot, to place the last symbol used as far forward as possible, and to minimize the average latency time for URLLC terminal users. Based on this policy, the second allocation decision device 240 may determine the actual allocation using methods such as exhaustive search, machine learning, or a QUBO problem solver. If the first fixed time is short, the second allocation decision device 240 may modify the allocation algorithm, such as narrowing the search range for the optimal solution or using an algorithm that is easier to compute. If the first fixed time is long, the second allocation decision device 240 may use an algorithm with a wide search range, such as exhaustive search for the optimal combination.

[0161] The control device 44 may send an allocation request to the first allocation device 230 after the second allocation device 240. The second allocation device 240 notifies the first allocation device 230, either via the control device 44 or directly, of the communication block information allocated to the URLLC terminal. The control device 44 also notifies the first allocation device 230 of the information necessary for resource allocation, such as the amount of data at the terminal, the allowable delay time, and channel information. The first allocation device 230 allocates communication blocks other than those allocated to the URLLC terminal to the eMBB terminal. When the first allocation device 230 receives an allocation request from the control device 44, it sends the allocation information back to the control device 44 before the second fixed time elapses.

[0162] Examples of resource allocation policies for eMMB terminals followed by the first allocation decision device 230 include round-robin, maximum throughput, and proportional fairness. Based on this policy, the first allocation decision device 230 may determine the actual allocation using methods such as brute-force search, machine learning, or a solver for solving the QUBO problem. The first allocation decision device 230 may use a wide-range search algorithm if the second fixed time is short, or a wide-range search algorithm if the second fixed time is long. Since eMMB terminals do not have strict latency requirements, they do not need to transmit all data within the latency time or within one slot, and may carry over to the next slot.

[0163] The control device 44 may send an allocation request to the third allocation device 250 after the first allocation device 230. The first allocation device 230 notifies the third allocation device 250, either via the control device 44 or directly, of the communication block information allocated to the eMBB terminal. The third allocation device 250 allocates communication blocks other than those allocated to the URLLC terminal and the eMBB terminal to the mMTC terminal. The control device 44 also notifies the third allocation device 250 of the information necessary for resource allocation, such as the amount of data at the terminal, the allowable delay time, and channel information. When the third allocation device 250 receives an allocation request from the control device 44, it sends the allocation information back to the control device 44 before the third fixed time elapses.

[0164] The proportions of the first, second, and third fixed time periods depend on the number of users, data volume, channel status, etc., for each terminal group. For example, if the number of users in the first terminal group increases, the first fixed time period may be lengthened, and the second and third fixed time periods may be shortened.

[0165] The sum of the first fixed time, the second fixed time, and the third fixed time is a time equivalent to the slot length.

[0166] Each of the first assignment determination device 230, the second assignment determination device 240, and the third assignment determination device 250 may include three assignment determination units, similar to the assignment determination device 222 shown in Figure 23.

[0167] The order in which the control device 44 transmits the allocation requests is not limited to the order of the second allocation determination device 240, the first allocation determination device 230, and the third allocation determination device 250 described above; other orders are also acceptable.

[0168] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0169] 20...Terminal, 30...Core network, 40...Base station, 42...Communication equipment, 44...Control device, 50...Allocation determination device, 52, 54...Allocation determination unit

Claims

1. A base station that communicates with terminals according to a communication standard, The system comprises an allocation determination device that receives an allocation request from the base station and determines the resources to be used for the communication, The aforementioned allocation request includes a first request and a second request, Each of the first and second requests includes identification information of the terminal, reference information relating to the terminal, and information representing the start time of the allocation process. The aforementioned reference information includes the allowable delay time for data transmitted and received by the terminal, the communication quality of data previously transmitted and received by the terminal, or information regarding the amount of data transmitted by the terminal. The assignment determination device comprises a first assignment determination unit that executes a first process in response to the first request and generates first assignment information, and a second assignment determination unit that executes a second process different from the first process in response to the second request and generates second assignment information. The first assignment determination unit outputs the first assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. The second assignment determination unit outputs the second assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. If either the first assignment information or the second assignment information satisfies the constraints defined by the communication standard, the assignment determination device transmits the first assignment information or the second assignment information that satisfies the constraints to the base station. The base station communicates with the terminal using the resources corresponding to the first assignment information or the second assignment information transmitted from the assignment determination device. The first assignment determination unit searches for the first assignment information within the first search range, The second assignment determination unit searches for the second assignment information within the second search range, A communication system in which the first search range is wider than the second search range.

2. A base station that communicates with terminals according to a communication standard, The system comprises an allocation determination device that receives an allocation request from the base station and determines the resources to be used for the communication, The allocation determination device comprises a first allocation determination unit and a second allocation determination unit that performs processing different from that of the first allocation determination unit. The first allocation determination unit determines the first allocation information from all combinations of terminals and resources, The second allocation determination unit determines the second allocation information from a subset of all combinations of terminals and resources. The first assignment determination unit outputs the first assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. The second assignment determination unit outputs the second assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. If either the first assignment information or the second assignment information satisfies the constraints defined by the communication standard, the assignment determination device transmits the first assignment information or the second assignment information that satisfies the constraints to the base station. The base station is a communication system that communicates with the terminal using resources corresponding to the first allocation information or the second allocation information transmitted from the allocation determination device.

3. The communication system according to claim 1 or 2, wherein the resource is at least one of time, frequency, space, power, code, and orbital angular momentum.

4. The allocation determination device is, The communication system according to claim 1 or 2, wherein if the first assignment information and the second assignment information satisfy the constraints, the first assignment information or the second assignment information which has a higher evaluation according to a predetermined evaluation method is transmitted to the base station.

5. The communication system according to claim 4, wherein the predetermined evaluation method gives a higher evaluation the better the transmission efficiency, the shorter the delay time, the higher the fairness between terminals, or the higher the delay achievement rate.

6. The probability that the first assignment information is valued higher than the second assignment information is higher than the probability that the second assignment information is valued higher than the first assignment information. The communication system according to claim 1 or 2, wherein the probability that the second assignment information satisfies the constraint is higher than the probability that the first assignment information satisfies the constraint.

7. The first assignment determination unit searches for the first assignment information within the first search range, The second assignment determination unit searches for the second assignment information within the second search range, The communication system according to claim 2, wherein the first search range is wider than the second search range.

8. The first allocation determination unit determines the first allocation information from all combinations of terminals and resources, The communication system according to claim 1, wherein the second allocation determination unit determines the second allocation information from a subset of all combinations of terminals and resources.

9. The aforementioned allocation determination device comprises a first allocation determination device and a second allocation determination device. The first allocation determination device determines the resources relating to the first type of terminal, The second allocation determination device determines the resources relating to the second type of terminal, The communication system according to claim 1 or claim 2, wherein the first type of terminal and the second type of terminal have different requirements regarding communication capacity or latency.

10. The aforementioned allocation determination device further comprises a third allocation determination unit, The third assignment determination unit outputs the third assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. The communication system according to claim 1 or 2, wherein the allocation determination device outputs to the base station the one among the first allocation information, the second allocation information, and the third allocation information that satisfies the constraints or has a high evaluation.

11. The communication system according to claim 1 or claim 2, wherein the communication standard is a standard for fifth-generation mobile communication systems.

12. A resource block consists of multiple symbols in the time direction and multiple subcarriers in the frequency direction. A mini-slot consists of two or more symbols that are part of the aforementioned multiple symbols, and multiple sub-carriers. The communication system according to claim 1 or claim 2, wherein the first allocation information and the second allocation information represent the allocation of resource elements to the terminal in mini-slot units.

13. A base station that communicates with terminals according to a communication standard, The system comprises an allocation determination device that receives an allocation request from the base station and determines the resources to be used for the communication, The aforementioned allocation request includes a first request and a second request, Each of the first and second requests includes identification information of the terminal, reference information relating to the terminal, and information representing the start time of the allocation process. The aforementioned reference information includes the allowable delay time for data transmitted and received by the terminal, the communication quality of data previously transmitted and received by the terminal, or information regarding the amount of data transmitted by the terminal. The aforementioned assignment determination device comprises a first assignment determination unit that executes a first process in response to a first request and generates first assignment information, and a second assignment determination unit that executes a second process different from the first process in response to a second request and generates second assignment information, and is a communication method for a communication system, The first assignment determination unit outputs the first assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. The second assignment determination unit outputs the second assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. If either the first assignment information or the second assignment information satisfies the constraints defined by the communication standard, the assignment determination device transmits the first assignment information or the second assignment information that satisfies the constraints to the base station. The base station communicates with the terminal using the resources corresponding to the first assignment information or the second assignment information transmitted from the assignment determination device. The first assignment determination unit searches for the first assignment information within the first search range, The second assignment determination unit searches for the second assignment information within the second search range, A communication method wherein the first search range is wider than the second search range.

14. A base station that communicates with terminals according to a communication standard, The system comprises an allocation determination device that receives an allocation request from the base station and determines the resources to be used for the communication, The aforementioned assignment determination device comprises a first assignment determination unit and a second assignment determination unit that performs processing different from that of the first assignment determination unit, and is a communication method for a communication system. The first allocation determination unit determines the first allocation information from all combinations of terminals and resources, The second allocation determination unit determines the second allocation information from a subset of all combinations of terminals and resources. The first assignment determination unit outputs the first assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. The second assignment determination unit outputs the second assignment information during the time from the start time of the assignment determination process to the start time of the assignment process. If either the first assignment information or the second assignment information satisfies the constraints defined by the communication standard, the assignment determination device transmits the first assignment information or the second assignment information that satisfies the constraints to the base station. A communication method comprising the base station communicating with the terminal using resources corresponding to the first allocation information or the second allocation information transmitted from the allocation determination device.

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