JP7688611B2 - Radio station, communication method, radio terminal, and radio communication system - Google Patents

Description

The present invention relates to a radio station, a communication method, a radio terminal, and a radio communication system used in wireless communication.

In a wireless communication system, a synchronization signal is transmitted from a base station to a wireless terminal at a predetermined period. Patent Document 1 discloses that a synchronization signal block (SSB) is transmitted periodically in a fifth-generation (5G) communication system.

Special Publication No. 2021-520128

In conventional wireless communication systems, a base station sequentially switches the direction in which it transmits a beam. Even if a beam is transmitted in a direction in which there is no wireless terminal, there is no wireless terminal that can receive the beam, so it is conceivable that the processing load on the base station can be reduced by not transmitting a beam in a direction in which there is no wireless terminal. However, because the wireless terminal needs to continue to sweep all directions in which the beam can be transmitted, there is a problem in that it is not possible to reduce the processing load.

The present invention was made in consideration of these points, and aims to reduce the load on wireless terminals that communicate with wireless stations.

A wireless station according to a first aspect of the present invention includes a beam transmission unit that transmits a wireless station beam directed to a wireless terminal to a predetermined range using multiple time slots corresponding to multiple directions, a direction estimation unit that estimates the direction of the wireless terminal, a range determination unit that determines the predetermined range based on the direction of the wireless terminal estimated by the direction estimation unit, and a notification unit that transmits notification data to the wireless terminal indicating at least one of one or more used time slots corresponding to the predetermined range or one or more unused time slots corresponding to a range other than the predetermined range.

The wireless station may further have a radio wave transmitting unit that transmits radio waves at a frequency lower than the radio station beam, and the notification unit may transmit the notification data to the wireless terminal by radio waves transmitted by the radio wave transmitting unit.

The wireless station may further have a radio wave transmitting unit that transmits radio waves having a lower directivity than the wireless station beam, and the notification unit may transmit the notification data to the wireless terminal by radio waves transmitted by the radio wave transmitting unit.

The beam transmitting unit may transmit an SSB beam using the multiple used time slots, and the notification unit may transmit the notification data to the wireless terminal using a type of beam other than the SSB beam transmitted by the beam transmitting unit.

The notification unit may transmit the notification data indicating a higher-order time slot including at least one of one or more used time slots or one or more unused time slots to the wireless terminal.

The notification unit may transmit to the wireless terminal the notification data indicating which used time slot the wireless station beam corresponding to is to be retransmitted in the one or more unused time slots.

The notification unit may transmit the notification data indicating the intended use of the one or more unused time slots to the wireless terminal.

A communication method according to a second aspect of the present invention includes the steps of transmitting a radio station beam aimed at a wireless terminal to a predetermined range using multiple time slots corresponding to multiple directions, estimating the direction of the wireless terminal, determining the predetermined range based on the estimated direction of the wireless terminal, and transmitting notification data indicating one or more used time slots corresponding to the predetermined range to the wireless terminal, executed by a computer.

A wireless terminal according to a third aspect of the present invention is a wireless terminal that communicates with the wireless station described above, and includes a terminal-side beam receiving unit that receives the wireless station beam transmitted by the wireless station, a notification data receiving unit that receives the notification data transmitted by the wireless station, and a control unit that controls the terminal-side beam receiving unit to receive the wireless station beam in the one or more time slots indicated by the notification data.

The wireless communication system of the fourth aspect of the present invention includes a wireless station and a wireless terminal capable of communicating with the wireless station. The wireless station includes a beam transmission unit that transmits a wireless station beam toward the wireless terminal to a predetermined range using multiple time slots corresponding to multiple directions, a direction estimation unit that identifies the direction of the wireless terminal, a range determination unit that determines the predetermined range based on the direction of the wireless terminal estimated by the direction estimation unit, and a notification unit that transmits notification data indicating one or more time slots corresponding to the predetermined range to the wireless terminal. The wireless terminal includes a terminal-side beam reception unit that receives the wireless station beam transmitted by the wireless station, a notification data reception unit that receives the notification data transmitted by the wireless station, and a control unit that controls the terminal-side beam reception unit to receive the wireless station beam in the one or more time slots indicated by the notification data.

The present invention has the effect of reducing the load on wireless terminals that communicate with wireless stations.

1 is a diagram showing a configuration of a wireless communication system S. 2 is a diagram showing an outline of a communication sequence between a wireless station 1 and a wireless terminal 2. FIG. A diagram showing the transmission timing of an SSB beam. A diagram showing the transmission timing of an SSB beam. 2 is a diagram showing a range in which a wireless station 1 sweeps a beam. FIG. FIG. 2 is a diagram showing a configuration of a wireless station 1. FIG. 2 is a diagram showing a configuration of a wireless terminal 2. 4 is a flowchart showing a process flow of the wireless station 1; FIG. 2 is a communication sequence diagram of the wireless communication system S. FIG. 11 is a diagram illustrating a configuration of a wireless station 1A according to a second embodiment.

First Embodiment
[Overview of wireless communication system S]
1 to 4 are diagrams for explaining an overview of a wireless communication system S. FIG. 1 is a diagram showing a configuration of the wireless communication system S. The wireless communication system S has a wireless station 1 and a wireless terminal 2. The wireless station 1 functions as a master station in wireless communication and is, for example, a base station or a relay station. The wireless terminal 2 functions as a slave station in wireless communication and is, for example, a smartphone or a tablet. The wireless communication network of this embodiment is, for example, a 5G wireless communication network, but the type of the wireless communication network is arbitrary.

The wireless station 1 and the wireless terminal 2 are configured to be able to communicate with each other using a first communication means that uses millimeter wave band radio waves like a 5G wireless communication system, and a second communication means that uses radio waves at a lower frequency than the first communication means. The wireless station 1 and the wireless terminal 2 use the first communication means to transmit and receive actual data used by the user of the wireless terminal 2. In addition, the wireless station 1 and the wireless terminal 2 use the second communication means to transmit and receive information regarding time slots used in the first communication means. Details of the time slots will be described later.

Figure 2 is a diagram showing an overview of the communication sequence between wireless station 1 and wireless terminal 2. Wireless station 1 and wireless terminal 2 communicate with each other while sequentially changing the direction in which the beam is swept. Each ellipse in Figure 2 shows a schematic representation of the shape of the beam. The shaded ellipse indicates a beam corresponding to a direction in which wireless station 1 and wireless terminal 2 are transmitting and receiving beams at a certain point in time, and the white ellipse indicates a beam corresponding to a direction in which wireless station 1 and wireless terminal 2 are not transmitting and receiving beams at that point in time.

Wireless station 1 and wireless terminal 2 communicate with each other while sequentially changing the direction in which the beam is swept. Each ellipse in Figure 2 shows a schematic representation of the shape of the beam. The shaded ellipse indicates a beam corresponding to a direction in which wireless station 1 and wireless terminal 2 are transmitting and receiving beams at a certain point in time, and the white ellipse indicates a beam corresponding to a direction in which wireless station 1 and wireless terminal 2 are not transmitting or receiving beams at that point in time.

In the initial stage, wireless station 1 sequentially transmits SSB beams, which are synchronization signal blocks, in all directions at a period of 20 ms. When wireless terminal 2 receives the SSB beam, it transmits a response beam to wireless station 1 indicating information (beam ID) for identifying the SSB beam with the highest received power.

Next, wireless station 1 sequentially transmits a channel state information estimation reference signal (CSI-RS) in multiple directions using a beam narrower than in the initial stage within the range corresponding to the beam ID indicated by the response beam received from wireless terminal 2. Wireless terminal 2 transmits a response beam indicating the beam ID of the beam with the maximum received power toward wireless station 1. Wireless station 1 then starts transmission using the beam ID indicated by the response beam, and wireless terminal 2 starts reception in the direction in which the received power of the beam corresponding to that beam ID is maximum. This starts transmission and reception of actual data (DATA) between wireless station 1 and wireless terminal 2.

Figures 3 and 4 are diagrams showing the transmission timing of an SSB beam. The horizontal axis in Figures 3 and 4 indicates time. As shown in Figures 3 and 4, an SSB beam is transmitted at a period of 20 ms, with timing corresponding to multiple transmission time slots within one radio frame.

Conventional wireless station 1 transmits SSB beams in all time slots in which it is possible to transmit SSB beams. However, even if an SSB beam is transmitted in a time slot corresponding to a direction in which it is estimated that no wireless terminal 2 is present, the SSB beam is not received by the wireless terminal 2, resulting in wasted resources. Therefore, the wireless station 1 of this embodiment is characterized in that it does not transmit an SSB beam in a time slot corresponding to a direction in which it is estimated that no wireless terminal 2 is present (for example, time slot SSB#2 shown in gray in FIG. 2). By configuring the wireless station 1 in this way, the processing load of the wireless station 1 is reduced.

However, even if the processing load of wireless station 1 is reduced by configuring wireless station 1 as described above, the processing load of wireless terminal 2 will not be reduced if wireless terminal 2 transmits beams in all directions. Therefore, wireless station 1 in this embodiment is characterized in that it notifies wireless terminal 2 of information regarding the timing (i.e., time slot) or direction at which wireless station 1 transmits a beam. Based on the notified information, wireless terminal 2 can sweep the beam excluding the timing or direction at which the beam is not transmitted, thereby reducing the processing load of wireless terminal 2.

Figure 5 is a diagram showing the range in which wireless station 1 sweeps its beam. In Figure 5, θ is the deflection angle based on the first axis of a spherical coordinate system whose origin is the position of wireless station 1, and φ is the deflection angle based on the second axis perpendicular to the first axis. Each of the solid-line circles arranged at equal intervals in the θ-axis and φ-axis directions indicates the irradiation range of the beam in one direction. The dashed-line circles indicate the range in a direction in which no wireless terminal 2 is present (hereinafter sometimes referred to as the "terminal-absent range").

In this case, wireless station 1 does not transmit beams shown in gray that are included in the terminal absence range. In other words, wireless station 1 does not transmit SSB beams at the timings when it transmits beams shown in gray. Wireless station 1 transmits SSB beams only at the timings when it transmits beams shown in white. The timings for transmitting beams shown in gray are, for example, the timings assigned to time slot SSB#2 shown in gray in Figure 3, and the timings assigned to time slots SSB#0 to SSB#3 shown in gray in Figure 4.

The configuration of the wireless station 1 that operates in this manner will be described in detail below. In the following description, the beam transmitted by the wireless station 1 will be referred to as a wireless station beam, and the beam transmitted by the wireless terminal 2 will be referred to as a terminal beam.

[Configuration of Wireless Station 1]
6 is a diagram showing the configuration of the wireless station 1. The wireless station 1 has a first communication unit 10, a second communication unit 11, a storage unit 12, and a control unit 13. The first communication unit 10 has a beam transmission unit 101 and a beam reception unit 102. The control unit 13 has an azimuth estimation unit 131, a range determination unit 132, a sweep control unit 133, and a notification unit 134.

The first communication unit 10 is a first communication means that functions as a beam sweep unit that sweeps a beam in a range specified by the sweep control unit 133. The beam transmission unit 101 transmits a radio station beam (e.g., an SSB beam) directed to the wireless terminal 2 to a predetermined range using multiple time slots corresponding to multiple directions. The beam transmission unit 101 transmits a radio station beam directed to one or more wireless terminals 2 while changing the direction at a predetermined period. The beam transmission unit 101 transmits a radio station beam to a range specified by the sweep control unit 133.

The beam receiving unit 102 receives terminal beams from one or more wireless terminals 2 after the beam transmitting unit 101 transmits a wireless station beam. The beam receiving unit 102 receives terminal beams arriving from a range specified by the sweep control unit 133. When the beam receiving unit 102 receives a terminal beam, it inputs an electrical signal based on the received terminal beam to the direction estimating unit 131.

The second communication unit 11 is a second communication means for transmitting information related to communication using the first communication unit 10 to the wireless terminal 2. The second communication unit 11 functions as a radio wave transmitting unit that transmits radio waves that have a lower frequency than a radio station beam and are less direct than a radio station beam, such as radio waves of Wi-Fi (registered trademark) or Bluetooth (registered trademark). The second communication unit 11 transmits radio waves including notification data based on instructions from the notification unit 134.

The storage unit 12 includes storage media such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 12 stores programs executed by the control unit 13. The storage unit 12 also stores data used by the control unit 13 to estimate the direction of the wireless terminal 2 and sweep the beam within the range of the estimated direction. The storage unit 12 stores, for example, direction history data that associates the direction in which the beam receiving unit 102 received a terminal beam with the time at which the terminal beam was received. The storage unit 12 also stores data indicating the range in which the wireless terminal 2 exists and data indicating the timing (e.g., time slot) for transmitting a wireless station beam.

The control unit 13 has, for example, a CPU (Central Processing Unit). The control unit 13 executes the programs stored in the storage unit 12 to function as an orientation estimation unit 131, a range determination unit 132, a sweep control unit 133, and a notification unit 134.

The direction estimation unit 131 estimates one or more directions corresponding to one or more wireless terminals 2. The direction estimation unit 131 creates direction history data including the results of estimating the direction of the wireless terminal 2 that transmitted the terminal beam by analyzing the terminal beam (e.g., a response beam) input from the beam receiving unit 102, and stores the created direction history data in the memory unit 12.

Specifically, the direction estimation unit 131 creates direction history data that associates the time when the beam receiving unit 102 received the terminal beam with coordinates indicating the estimated direction. For example, each time the direction estimation unit 131 estimates the direction of the wireless terminal 2 based on the terminal beam input from the beam receiving unit 102, it adds the coordinates and time of the new direction to the direction history data stored in the memory unit 12.

After adding a direction to the direction history data, the direction estimation unit 131 may delete the direction from the direction history data when the wireless terminal 2 is no longer present in that direction. For example, when the beam reception unit 102 does not receive a response beam in response to the transmission of an SSB beam by the beam transmission unit 101, the direction estimation unit 131 deletes the direction in which the beam transmission unit 101 transmitted the SSB beam from the direction history data.

The direction estimation unit 131 may estimate the direction of the wireless terminal 2 using any method. For example, the direction estimation unit 131 estimates the direction of the wireless terminal 2 using the following equation (1).
Here, P(θ) is the power of the terminal beam received by the beam receiving unit 102 from the angle θ.

The range determination unit 132 determines a predetermined range in which the beam transmission unit 101 transmits a beam based on the direction of the wireless terminal 2 estimated by the direction estimation unit 131. That is, the range determination unit 132 determines a terminal direction range including one or more directions estimated by the direction estimation unit 131. The terminal direction range coincides with the irradiation range of one or more wireless station beams corresponding to one or more directions estimated by the direction estimation unit 131 that the wireless terminal 2 exists, for example. The range determination unit 132 may set the terminal direction range to a range that includes a margin in addition to the irradiation range of one or more wireless station beams in which the wireless terminal 2 exists. As an example, the range determination unit 132 may include the irradiation range of a wireless station beam adjacent to the irradiation range of one or more wireless station beams in which the wireless terminal 2 exists, in the terminal direction range.

The sweep control unit 133 controls the beam transmission unit 101 and the beam reception unit 102. The sweep control unit 133 controls the beam transmission unit 101 to transmit radio station beams at one or more first timings corresponding to one or more directions included in the terminal direction range determined by the range determination unit 132, and not to transmit radio station beams at one or more second timings corresponding to ranges outside the terminal direction range. The first timings are, for example, the transmission timings of time slots SSB#0, SSB#1, and SSB#3 shown in white in FIG. 3, and the second timing is the transmission timing of time slot SSB#2 shown in gray in FIG. 3.

The terminal direction range includes the direction of the wireless terminal 2 estimated by the direction estimation unit 131 within the specified period. Therefore, the sweep control unit 133 determines whether or not to transmit a wireless station beam based on the terminal direction range determined by the range determination unit 132, and controls the beam transmission unit 101 to transmit a wireless station beam to a range excluding the direction of the wireless terminal 2 that is not stored in the storage unit 12 for the specified period. The sweep control unit 133 then controls the beam transmission unit 101 not to transmit a wireless station beam to the direction of the wireless terminal 2 that is not stored in the storage unit 12 for the specified period. The specified period is, for example, one minute, which is a period during which it can be determined that the wireless terminal 2 has moved.

The sweep control unit 133 may control the beam transmission unit 101 to retransmit, at a second timing corresponding to an unused time slot corresponding to a range other than the terminal direction range, a radio station beam including the same data as that included in the radio station beam transmitted at a first timing corresponding to a used time slot corresponding to the terminal direction range. For example, the sweep control unit 133 causes the beam transmission unit 101 to retransmit, at an unused time slot, an SSB beam transmitted at a used time slot. At this time, the sweep control unit 133 causes the beam transmission unit 101 to transmit the same SSB beam in the unused time slot in the direction in which the SSB beam was transmitted at the used time slot.

Specifically, in the example shown in FIG. 3, the sweep control unit 133 causes the beam transmitting unit 101 to transmit the SSB beam transmitted by the beam transmitting unit 101 in time slot SSB#1 also in time slot SSB#2. By operating the sweep control unit 133 in this manner, the same SSB beam is retransmitted in the same direction. Therefore, even if noise temporarily occurs in that direction at the timing of time slot SSB#1, the wireless terminal 2 can receive the SSB beam in time slot SSB#2, improving the signal-to-noise ratio.

The sweep control unit 133 may control the beam transmission unit 101 to transmit a radio station beam including first use data at a first timing corresponding to a used time slot, and to transmit a radio station beam including second use data different from the first use data at a second timing corresponding to an unused time slot. The first use data is, for example, data included in an SSB beam, and the second use data is data included in a PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), or CSI-RS (Channel Status Information Reference Signal) beam. By operating in this manner, the sweep control unit 133 effectively utilizes the transmission timing of the SSB beam that does not contribute to communication between the radio station 1 and the radio terminal 2, and the actual communication capacity in the radio communication system S is increased.

The sweep control unit 133 may set the second timing, at which the radio station beam is not transmitted, to the timing at which the terminal beam is received from the radio terminal 2. In this case, the sweep control unit 133 controls the beam receiving unit 102 to receive the terminal beam transmitted from the radio terminal at the second timing.

The notification unit 134 transmits and receives data to and from the wireless terminal 2 via the second communication unit 11. The notification unit 134 transmits notification data to the wireless terminal 2 indicating one or more used time slots corresponding to the terminal direction range in which the beam transmission unit 101 transmits a wireless station beam. The notification unit 134 transmits the notification data to the wireless terminal 2 by radio waves transmitted by the second communication unit 11, which functions as a radio wave transmission unit.

The wireless station 1 stores in the storage unit 12 identification information of the wireless terminal 2 required for communicating with the wireless terminal 2 via Wi-Fi or Bluetooth, and the notification unit 134 may set the second communication unit 11 to a state in which it can communicate with the wireless terminal 2 by referring to the identification information stored in the storage unit 12 before transmitting the notification data. The notification unit 134 transmits the notification data to the wireless terminal 2 after the second communication unit 11 is able to communicate with the wireless terminal 2.

The notification data may include identification information for identifying the SSB beam to be transmitted as information indicating the time slot to be used, or may include a time slot number. If the wireless terminal 2 stores the relationship between the direction and the time slot, the notification unit 134 may transmit notification data including information indicating the direction in which the wireless station beam is to be transmitted as information indicating the time slot to be used.

The notification data may include information indicating unused time slots. In the example shown in FIG. 3, the notification unit 134 transmits notification data indicating time slot SSB#2, which is shown in gray in FIG. 3. In the example shown in FIG. 4, the notification unit 134 transmits notification data indicating time slots SSB#0 to SSB#3, which are shown in gray in FIG. 4.

The notification unit 134 may transmit notification data to the wireless terminal 2 indicating an upper time slot that includes at least one of one or more used time slots or one or more unused time slots. An upper time slot is a time slot that includes multiple lower time slots, and in the example shown in FIG. 4, "Slot #0" is the upper time slot of time slot SSB #0 and time slot SSB #1. "SSB #0-3" is the upper slot of "Slot #0" and "Slot #1".

As shown in FIG. 4, when time slots SSB#0 to #3 are not in use, the notification unit 134 may transmit notification data indicating that "Slot#0" and "Slot#1" are unused time slots. The notification unit 134 may also transmit notification data indicating that the SSB transmission slots "SSB#0-3" are unused time slots.

As described above, when the sweep control unit 133 causes the beam transmitting unit 101 to retransmit an SSB beam transmitted in a used time slot in an unused time slot, the notification unit 134 may cause the beam receiving unit 102 to transmit notification data indicating which used time slot the radio station beam corresponding to is to be retransmitted in for one or more unused time slots. The sweep control unit 133 causes the beam receiving unit 102 to transmit, for example, notification data indicating which other time slot the SSB beam of which time slot is to be retransmitted in.

By the notification unit 134 transmitting such notification data, the wireless terminal 2 can wait to receive the SSB beam at multiple time slots during which the SSB beam may be transmitted. Therefore, even if the SSB beam cannot be received at one time slot due to noise, temporary obstructions, etc., the SSB beam can be received at another time slot.

In addition, when the sweep control unit 133 transmits a type of beam other than an SSB beam in an unused time slot, the notification unit 134 may transmit to the wireless terminal 2 notification data indicating the purpose of one or more unused time slots. As an example, when the sweep control unit 133 causes the beam transmission unit 101 to transmit a PDCCH beam in an unused time slot, the notification unit 134 transmits to the wireless terminal 2 notification data indicating that a PDCCH will be transmitted in the unused time slot, together with information for identifying the unused time slot. By the notification unit 134 transmitting such notification data, the wireless terminal 2 can properly receive beams other than an SSB beam.

[Configuration of Wireless Terminal 2]
7 is a diagram showing a configuration of the wireless terminal 2. The wireless terminal 2 has a first communication unit 20, a second communication unit 21, a storage unit 22, and a control unit 23. The first communication unit 20 has a beam transmitting unit 201 and a beam receiving unit 202.

The first communication unit 20 transmits and receives beams to and from the wireless station 1. The beam transmission unit 201 functions as a terminal-side beam transmission unit that transmits a terminal beam to the wireless station 1 based on the control of the control unit 23. The beam reception unit 202 functions as a terminal-side beam reception unit that receives a wireless station beam transmitted by the wireless station 1.

The second communication unit 21 is a communication means for receiving notification data transmitted by the wireless station 1. The second communication unit 21 transmits and receives radio waves, for example, Wi-Fi or Bluetooth.

The storage unit 22 includes storage media such as ROM and RAM. The storage unit 22 stores a program executed by the control unit 23. The storage unit 22 also stores information included in the notification data received by the second communication unit 21 from the wireless station 1. Specifically, the storage unit 22 stores identification information of used time slots (e.g., time slot numbers) and identification information of unused time slots. The storage unit 22 may further store information indicating the timing of multiple time slots corresponding to each identification information, and information indicating the direction corresponding to each time slot.

The control unit 23 has, for example, a CPU. The control unit 23 executes a program stored in the storage unit 22 to control the beam receiving unit 202 to receive a radio station beam in one or more time slots indicated by the notification data.

[Processing flow of wireless station 1]
Fig. 8 is a flowchart showing the flow of processing in the wireless station 1. The flowchart shown in Fig. 8 starts from the point in time when the wireless station 1 starts its operation.

First, the sweep control unit 133 controls the beam transmission unit 101 to transmit a radio station beam in a time slot corresponding to the initially set timing (S1). The initially set timing is all the timings at which the radio station beam can be transmitted.

Then, the direction estimation unit 131 identifies the direction of the wireless terminal 2 based on the direction in which the terminal beam was received from the wireless terminal 2 (S2). The range determination unit 132 determines a terminal direction range, which is the range of directions in which the terminal exists, based on the directions of the multiple wireless terminals 2 identified by the direction estimation unit 131 (S3). The range determination unit 132 notifies the sweep control unit 133 that the terminal direction range has been determined. The range determination unit 132 also stores the determined terminal direction range in the memory unit 12.

When the sweep control unit 133 receives a notification from the range determination unit 132 that the terminal direction range has been determined, the sweep control unit 133 compares the terminal direction range stored in the storage unit 12 with the determined terminal direction range to determine whether the terminal direction range has been changed (S4). If the sweep control unit 133 determines that the terminal direction range has been changed (YES in S4), it changes the timing for transmitting the radio station beam (S5).

Specifically, the sweep control unit 133 excludes the used time slots corresponding to the directions not included in the terminal direction range from the time slots for transmitting the radio station beam, and changes them to unused time slots. If the sweep control unit 133 determines that the terminal direction range has not been changed (NO in S4), it does not change the timing for transmitting the radio station beam.

When the sweep control unit 133 changes the transmission timing, it transmits notification data indicating at least one of the changed used time slots or one or more unused time slots to the wireless terminal 2 (S6). The control unit 13 repeats the processes from S2 to S6 until an operation to end the operation of transmitting the wireless station beam is received (NO in S7).

[Sequence of wireless communication system S]
Fig. 9 is a communication sequence diagram of the wireless communication system S. The communication sequence diagram shown in Fig. 9 starts from the point in time when the sweep control unit 133 changes the transmission timing (S5) in the flowchart in Fig. 8. The solid arrows in Fig. 9 indicate data communicated between the second communication unit 11 and the second communication unit 21, and the dashed lines indicate beams communicated between the first communication unit 10 and the first communication unit 20.

When the sweep control unit 133 changes the transmission timing, the notification unit 134 of the wireless station 1 transmits notification data to the wireless terminal 2, for example, via Wi-Fi or Bluetooth, and the wireless terminal 2 transmits response data to the wireless station 1.

The wireless terminal 2 changes the reception timing based on the notification data (S11), and then receives the SSB beam transmitted in the time slot corresponding to the reception timing (S12). If the wireless terminal 2 has data to transmit to the wireless station 1 (YES in S13), it refers to the timing notified in the notification data and transmits the data using a time slot in which data can be transmitted.

[Modification]
In the above description, the notifying unit 134 transmits the notification data to the wireless terminal 2 using Wi-Fi or Bluetooth, etc., but the means by which the notifying unit 134 transmits the notification data to the wireless terminal 2 is not limited to this. The notifying unit 134 may transmit the notification data to the wireless terminal 2 using a type of beam other than the SSB beam transmitted by the beam transmitting unit 101. For example, the notifying unit 134 may transmit the notification data to the wireless terminal 2 using a physical broadcast channel (PBCH) used to notify the wireless terminal 2 of parameters for receiving a wireless station beam. By configuring the notifying unit 134 in this way, even if the wireless terminal 2 is in a position where it cannot communicate with the wireless station 1 via Wi-Fi or Bluetooth, the wireless terminal 2 can obtain information regarding the used time slot or the unused time slot.

Second Embodiment
10 is a diagram showing the configuration of a wireless station 1A according to the second embodiment. In the wireless station 1 according to the first embodiment, when a wireless terminal 2 is present, the direction estimated by the direction estimation unit 131 is set as the terminal direction range, but an error may occur in the direction estimated by the direction estimation unit 131. Therefore, the wireless station 1A is characterized in that it determines the terminal direction range taking the error into consideration.

As shown in FIG. 6, wireless station 1A differs from wireless station 1 shown in FIG. 6 in that the control unit 13 further includes a moving speed determination unit 135 and a calculation unit 136, but is otherwise the same. The following description will focus on the differences from wireless station 1.

The moving speed determination unit 135 determines the moving speed of the wireless terminal 2 at multiple points in time based on the relationship between the multiple directions in which the wireless terminal 2 was present and the multiple times that are estimated by the direction estimation unit 131 at multiple times and stored in the memory unit 12. Specifically, the moving speed determination unit 135 calculates the moving speed relative to other wireless stations using the following formula (2).

Here, Δt is the time interval during which the orientation of the wireless terminal 2 is stored, N is the number of orientations included in the orientation history data, and θ _i is the orientation at the i-th time.

In this case, the direction estimation unit 131 estimates the direction at the next time by the following equation (3).

The calculation unit 136 calculates a variation value indicating the magnitude of variation in multiple moving speeds corresponding to multiple time points. The variation value is expressed by a statistical value such as the variance or standard deviation of the moving speeds, for example.

The calculation unit 136 calculates the standard deviation as a variation value, for example, by the following formula (4).
Here, N is the number of past directions used to calculate the dispersion value, v _i is the moving speed at time i, and v _a is the average moving speed.

The range determination unit 132 estimates the terminal orientation range of the wireless terminal 2 at the next time based on the previous orientation of the wireless terminal 2, the movement speed identified by the movement speed identification unit 135, and the variation value. The range determination unit 132 estimates the position of other wireless stations at the next time based on, for example, the previous orientation of the wireless terminal 2 and the latest movement speed identified by the movement speed identification unit 135, and calculates the terminal orientation range taking into account the error based on the position to be estimated and the variation value.

Specifically, the range determination unit 132 estimates the error range of the azimuth of another wireless station at the next time, for example, using the following equation (5).
The range determination unit 132 determines the terminal direction range taking the error into consideration by adding the error range calculated by formula (5) to the direction at the next time calculated by formula (3). The range determination unit 132 notifies the determined terminal direction range to the sweep control unit 133. The sweep control unit 133 controls the beam transmission unit 101 and the beam reception unit 102 based on the notified terminal direction range in the same way as the wireless station 1 of the first embodiment.

[Effects of the wireless station 1A of the second embodiment]
As described above, the sweep control unit 133 of the wireless station 1A estimates the direction of the wireless terminal 2 at the next time, and controls the first communication unit 10 using the terminal direction range that takes into account the error included in the estimated direction. By configuring the wireless station 1A in this way, even when the wireless terminal 2 moves, the wireless station 1A can transmit a wireless station beam at a timing corresponding to the direction in which the wireless terminal 2 is present, and can avoid transmitting a wireless station beam at a timing corresponding to the direction in which the wireless terminal 2 is not present.

Furthermore, this invention will make it possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote innovation and infrastructure."

Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination also has the effect of the original embodiment.

REFERENCE SIGNS LIST 1 Wireless station 2 Wireless terminal 10 First communication unit 11 Second communication unit 12 Memory unit 13 Control unit 20 First communication unit 21 Second communication unit 22 Memory unit 23 Control unit 101 Beam transmission unit 102 Beam reception unit 131 Direction estimation unit 132 Range determination unit 133 Sweep control unit 134 Notification unit 135 Travel speed identification unit 136 Calculation unit 201 Beam transmission unit 202 Beam reception unit

Claims (9)

a beam transmitting unit that transmits a radio station beam toward a radio terminal to a predetermined range by using a plurality of time slots corresponding to a plurality of directions;
An orientation estimation unit that estimates an orientation of the wireless terminal;
a range determination unit that determines the predetermined range based on the direction of the wireless terminal estimated by the direction estimation unit;
a notification unit configured to transmit, to the wireless terminal, notification data indicating at least one of one or more used time slots corresponding to the predetermined range or one or more unused time slots corresponding to a range other than the predetermined range;
having
The notification unit transmits the notification data to the wireless terminal, indicating which used time slot the wireless station beam corresponding to will be retransmitted in the one or more unused time slots . The wireless station further includes a radio wave transmitting unit that transmits a radio wave having a frequency lower than that of the wireless station beam,
The notification unit transmits the notification data to the wireless terminal by radio waves transmitted by the radio wave transmission unit.
The radio station according to claim 1. The radio station further includes a radio wave transmitting unit that transmits radio waves having a lower linearity than the radio station beam,
The notification unit transmits the notification data to the wireless terminal by radio waves transmitted by the radio wave transmission unit.
The radio station according to claim 1. The beam transmitting unit transmits an SSB beam using the plurality of used time slots,
The notification unit transmits the notification data to the wireless terminal using a beam of a type other than the SSB beam transmitted by the beam transmission unit.
The radio station according to claim 1. The notification unit transmits the notification data indicating a higher order time slot including at least one of one or more used time slots or one or more unused time slots to the wireless terminal.
A radio station according to any one of claims 1 to 4. a beam transmitting unit that transmits a radio station beam toward a radio terminal to a predetermined range by using a plurality of time slots corresponding to a plurality of directions;
An orientation estimation unit that estimates an orientation of the wireless terminal;
a range determination unit that determines the predetermined range based on the direction of the wireless terminal estimated by the direction estimation unit;
a notification unit configured to transmit, to the wireless terminal, notification data indicating at least one of one or more used time slots corresponding to the predetermined range or one or more unused time slots corresponding to a range other than the predetermined range;
having
The notification unit transmits the notification data indicating a use of the one or more unused time slots to the wireless terminal.
Radio station. The computer executes
transmitting a radio station beam toward a radio terminal to a predetermined range using a plurality of time slots corresponding to a plurality of directions;
estimating an orientation of the wireless terminal;
determining the predetermined range based on an estimated orientation of the wireless terminal;
transmitting notification data to the wireless terminal indicating one or more used time slots corresponding to the predetermined range;
transmitting to the wireless terminal the notification data indicating which of the one or more unused time slots the wireless station beam corresponding to the used time slot is to be retransmitted;
A communication method comprising: A wireless terminal for communicating with the wireless station according to claim 1,
a terminal side beam receiving unit for receiving the radio station beam transmitted by the radio station;
a notification data receiving unit for receiving the notification data transmitted by the wireless station;
a control unit that controls the terminal side beam receiving unit to receive the radio station beam in the one or more time slots or the one or more unused time slots indicated by the notification data;
A wireless terminal having the above configuration. A wireless communication system comprising: a wireless station; and a wireless terminal capable of communicating with the wireless station;
The radio station,
a beam transmitting unit that transmits a radio station beam toward a radio terminal to a predetermined range by using a plurality of time slots corresponding to a plurality of directions;
An orientation estimation unit that identifies an orientation of the wireless terminal;
a range determination unit that determines the predetermined range based on the direction of the wireless terminal estimated by the direction estimation unit;
a notification unit configured to transmit, to the wireless terminal, notification data indicating one or more time slots corresponding to the predetermined range;
having
the notification unit transmits to the wireless terminal the notification data indicating which used time slot the radio station beam corresponding to is to be retransmitted in the one or more unused time slots;
The wireless terminal,
a terminal side beam receiving unit for receiving the radio station beam transmitted by the radio station;
a notification data receiving unit for receiving the notification data transmitted by the wireless station;
a control unit that controls the terminal side beam receiving unit to receive the radio station beam in the one or more time slots or the one or more unused time slots indicated by the notification data;
A wireless communication system having the following:

Images