Wireless station and communication method

Abstract

To prevent resources of radio stations from being consumed wastefully.SOLUTION: A radio station 1 includes: a beam transmitting unit 111 that transmits a radio station beam toward one or more wireless terminals 2 while changing its orientation in a predetermined period; a beam receiving unit 112 that receives terminal beams from the one or more wireless terminals 2 after the beam transmitting unit 111 has transmitted the radio station beam; an orientation estimation unit 131 that estimates one or more orientations corresponding to the one or more wireless terminals 2; a range determination unit 132 that determines a terminal orientation range including the one or more orientations estimated by the orientation estimation unit 131; and a sweep control unit 133 that controls the beam transmitting unit to transmit the radio station beam at one or more first timings corresponding to the one or more orientations included in the terminal orientation range, and not to transmit the radio station beam at one or more second timings corresponding to a range other than the terminal orientation range.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a wireless station used for wireless communication and a communication method of the wireless station.

Background Art

[0002] 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 in a fifth-generation (5G) communication system, a synchronization signal block SSB is transmitted periodically.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional system, a beam including a synchronization signal is transmitted at a predetermined period even in a direction where there is no wireless terminal. Although such a beam does not contribute to communication between the base station and the wireless terminal, there has been a problem that useless resources of the base station are consumed.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to prevent useless resources of the wireless station from being consumed.

Means for Solving the Problems

[0006] The wireless station according to the first aspect of the present invention includes a beam transmission unit that transmits a wireless station beam directed to one or more wireless terminals while changing the orientation at a predetermined period, a beam reception unit that receives a terminal beam from the one or more wireless terminals after the beam transmission unit transmits the wireless station beam, an orientation estimation unit that estimates one or more orientations corresponding to the one or more wireless terminals, a range determination unit that determines a terminal orientation range including the one or more orientations estimated by the orientation estimation unit, and a sweep control unit that controls the beam transmission unit to transmit the wireless station beam at one or more first timings corresponding to one or more orientations included in the terminal orientation range and not to transmit the wireless station beam at one or more second timings corresponding to a range outside the terminal orientation range.

[0007] The sweep control unit may control the beam transmission unit to retransmit the wireless station beam including the same data as the data included in the wireless station beam transmitted at the first timing at the second timing.

[0008] The sweep control unit may control the beam transmission unit to transmit the wireless station beam including first use data at the first timing and transmit the wireless station beam including second use data different from the first use data at the second timing.

[0009] The sweep control unit may control the beam reception unit to receive the terminal beam transmitted from the wireless terminal at the second timing.

[0010] The wireless station further includes a storage unit that stores the orientation of the wireless terminal in association with time, and the sweep control unit may control the beam transmission unit to transmit the wireless station beam in a range excluding the orientation of the wireless terminal not stored in the storage unit over a predetermined period.

[0011] The wireless station may further include a moving speed specifying unit that specifies the moving speed of the wireless terminal with respect to the wireless station, a calculating unit that calculates a variation value indicating the magnitude of the variations in the plurality of moving speeds corresponding to a plurality of time points, and a specifying unit that specifies the terminal azimuth range at the next time based on the azimuth of the terminal beam that the beam receiving unit has just received from the wireless terminal, the moving speed, and the variation value.

[0012] The communication method according to the second aspect of the present invention includes steps of: a computer transmitting a wireless station beam directed at one or more wireless terminals to a beam transmitting unit while changing the azimuth at a predetermined period; receiving a terminal beam from the wireless terminal after transmitting the wireless station beam; estimating one or more azimuths corresponding to the one or more wireless terminals; determining a terminal azimuth range including the estimated one or more azimuths; transmitting the wireless station beam at one or more first timings corresponding to one or more azimuths included in the terminal azimuth range, and controlling the beam transmitting unit so as not to transmit the wireless station beam at one or more second timings corresponding to ranges outside the terminal azimuth range.

Advantages of the Invention

[0013] According to the present invention, there is an effect that it is possible to prevent the wasteful consumption of resources of the wireless station.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] <First Embodiment> [Overview of the Wireless Communication System S] FIGS. 1 to 3 are diagrams for explaining the overview of the wireless communication system S according to the present embodiment. FIG. 1 is a diagram showing an overview of a communication sequence between the wireless station 1 of the wireless communication network and the wireless terminal 2 that wirelessly communicates with the wireless station 1. 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 station 1 wirelessly communicates with one or more wireless terminals 2. The wireless communication network of the present embodiment is, for example, a 5G wireless communication network, but the type of the wireless communication network is arbitrary.

[0016] The wireless station 1 and the wireless terminal 2 communicate with each other while sequentially changing the azimuth for sweeping the beam. Each ellipse in FIG. 1 schematically shows the shape of the beam. The ellipse shown by the slanted lines indicates the beam corresponding to the azimuth at which the wireless station 1 and the wireless terminal 2 are transmitting and receiving the beam at a certain point in time, and the white ellipse indicates the beam corresponding to the azimuth at which the wireless station 1 and the wireless terminal 2 are not transmitting and receiving the beam at that point in time.

[0017] In the initial stage, the wireless station 1 sequentially transmits SSB beams, which are synchronization signal blocks, omnidirectionally at a period of 20 ms. When the wireless terminal 2 receives the SSB beam, it transmits a response beam indicating information (beam ID) for identifying the SSB beam with the maximum received power towards the wireless station 1.

[0018] Subsequently, within the range corresponding to the beam ID indicated by the response beam received from the wireless terminal 2, the radio station 1 sequentially transmits channel state information reference signals (CSI-RS) in a plurality of directions using beams that are narrower than in the initial stage. The wireless terminal 2 transmits a response beam indicating the beam ID of the beam with the maximum received power towards the radio station 1. Thereafter, the radio station 1 starts transmission using the beam ID indicated by the response beam, and the wireless terminal 2 starts reception in the direction where the received power of the beam corresponding to the beam ID is maximum. As a result, the transmission and reception of actual data (DATA) between the radio station 1 and the wireless terminal 2 are started.

[0019] Figure 2 is a diagram showing the transmission timing of the SSB beam. The horizontal axis in Figure 2 indicates time. As shown in Figure 2, the SSB beam is transmitted at a timing corresponding to a plurality of transmission time slots within one radio frame, with a period of 20 ms.

[0020] The conventional radio station 1 transmitted the SSB beam at all timings when it could transmit the SSB beam. However, even if the SSB beam is transmitted at a timing corresponding to a direction where the wireless terminal 2 is not presumed to exist, the SSB beam will not be received by the wireless terminal 2, resulting in the consumption of wasted resources. Therefore, the radio station 1 of the present embodiment is characterized by not transmitting the SSB beam at a timing corresponding to a direction where the wireless terminal 2 is not presumed to exist (for example, the timing of time slot SSB#2 shown in gray in Figure 2).

[0021] Figure 3 is a diagram showing the range within which the radio station 1 sweeps the beam. In Figure 3, θ is the declination angle with respect to the first axis of the spherical coordinate system with the position of the radio station 1 as the origin, and φ is the declination angle with respect to the second axis orthogonal to the first axis. Each of the solid circles arranged at equal intervals in the θ-axis direction and the φ-axis direction indicates the irradiation range of the beam in one direction. The dashed circle indicates the range of the direction where the wireless terminal 2 does not exist (hereinafter, may be referred to as the "terminal absence range").

[0022] In this case, the radio station 1 does not transmit the beams shown in gray that are included in the terminal absence range. That is, the radio station 1 does not transmit the SSB beam at the timing when the beam shown in gray is transmitted. Then, the radio station 1 transmits the SSB beam only at the timing when the beam shown in white is transmitted. The timing for transmitting the beam shown in gray is, for example, the timing assigned to the time slot SSB#2 shown in gray in FIG. 2.

[0023] Hereinafter, the configuration of the radio station 1 that operates in this way will be described in detail. In the following description, the beam transmitted by the radio station 1 is referred to as a radio station beam, and the beam transmitted by the wireless terminal 2 is referred to as a terminal beam.

[0024] [Configuration of Radio Station 1] FIG. 4 is a diagram showing the configuration of the radio station 1. The radio station 1 includes a communication unit 11, a storage unit 12, and a control unit 13. The communication unit 11 includes a beam transmission unit 111 and a beam reception unit 112. The control unit 13 includes a direction estimation unit 131, a range determination unit 132, and a sweep control unit 133.

[0025] The communication unit 11 functions as a beam sweeping unit that sweeps beams within the range instructed by the sweep control unit 133. The beam transmission unit 111 transmits a radio station beam directed to one or more wireless terminals while changing the direction at a predetermined period. The beam transmission unit 111 transmits the radio station beam within the range instructed by the sweep control unit 133.

[0026] After the beam transmission unit 111 transmits the radio station beam, the beam reception unit 112 receives a terminal beam from one or more wireless terminals 2. The beam reception unit 112 receives the terminal beam arriving from the range instructed by the sweep control unit 133. When the beam reception unit 112 receives the terminal beam, it inputs an electrical signal based on the received terminal beam to the direction estimation unit 131.

[0027] 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 the programs executed by the control unit 13. Further, the storage unit 12 stores data used for the control unit 13 to estimate the orientation of the wireless terminal 2 and sweep the beam within the estimated orientation range. The storage unit 12 stores, for example, orientation history data in which the orientation at which the beam reception unit 112 received the terminal beam is associated with the time when the terminal beam was received. Also, the storage unit 12 stores data indicating the range in which the wireless terminal 2 exists.

[0028] The control unit 13 includes, for example, a CPU (Central Processing Unit). The control unit 13 functions as an orientation estimation unit 131, a range determination unit 132, and a sweep control unit 133 by executing the programs stored in the storage unit 12.

[0029] The orientation estimation unit 131 estimates one or more orientations corresponding to one or more wireless terminals 2. The orientation estimation unit 131 creates orientation history data including the result of estimating the orientation of the wireless terminal 2 that transmitted the terminal beam (for example, the response beam) by analyzing the terminal beam input from the beam reception unit 112, and stores the created orientation history data in the storage unit 12.

[0030] Specifically, the orientation estimation unit 131 creates orientation history data in which the time when the beam reception unit 112 received the terminal beam is associated with the coordinates indicating the estimated orientation. The orientation estimation unit 131 adds, for example, the coordinates and time of the new orientation to the orientation history data stored in the storage unit 12 each time the orientation of the wireless terminal 2 is estimated based on the terminal beam input from the beam reception unit 112.

[0031] After adding the 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 no longer exists in the direction. For example, when the beam reception unit 112 does not receive the response beam corresponding to the SSB beam transmitted by the beam transmission unit 111, the direction estimation unit 131 deletes the direction in which the beam transmission unit 111 transmitted the SSB beam from the direction history data.

[0032] The method by which the direction estimation unit 131 estimates the direction of the wireless terminal 2 is arbitrary. However, the direction estimation unit 131 estimates the direction of the wireless terminal 2, for example, by the following formula (1).

Equation

[0033] Based on the direction of the wireless terminal 2 estimated by the direction estimation unit 131, the range determination unit 132 determines a predetermined range in which the beam transmission unit 101 transmits the beam. 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, for example, the irradiation ranges of one or more radio station beams corresponding to one or more directions estimated by the direction estimation unit 131 when the wireless terminal 2 exists. The range determination unit 132 may use, as the terminal direction range, a range obtained by adding a margin to the irradiation ranges of one or more radio station beams in which the wireless terminal 2 exists. As an example, the range determination unit 132 may include the irradiation ranges of radio station beams adjacent to the irradiation ranges of one or more radio station beams estimated to have the wireless terminal 2 in the terminal direction range.

[0034] The scanning control unit 133 controls the beam transmission unit 111 and the beam reception unit 112. The scanning control unit 133 transmits a radio station beam at one or more first timings corresponding to one or more azimuths included in the terminal azimuth range determined by the range determination unit 132, and does not transmit a radio station beam at one or more second timings corresponding to a range outside the terminal azimuth range, thereby controlling the beam transmission unit 111. The first timing is, for example, the transmission timings of time slots SSB#0, SSB#1, and SSB#3 shown in white in FIG. 2, and the second timing is the transmission timing of time slot SSB#2 shown in gray in FIG. 2.

[0035] The terminal azimuth range includes the azimuth of the wireless terminal 2 estimated by the azimuth estimation unit 131 within a predetermined period. Therefore, the scanning control unit 133 determines whether to transmit a radio station beam based on the terminal azimuth range determined by the range determination unit 132, thereby controlling the beam transmission unit 111 to transmit a radio station beam in a range excluding the azimuth of the wireless terminal 2 not stored in the storage unit 12 over a predetermined period. Then, the scanning control unit 133 controls the beam transmission unit 111 not to transmit a radio station beam at the azimuth of the wireless terminal 2 not stored in the storage unit 12 over a predetermined period. The predetermined period is, for example, a period in which it can be determined that the wireless terminal 2 has moved, which is one minute.

[0036] The scanning control unit 133 may control the beam transmission unit 111 to retransmit a radio station beam including the same data as the data included in the radio station beam transmitted at the first timing at the second timing. For example, the scanning control unit 133 causes the beam transmission unit 111 to retransmit the SSB beam transmitted at the first timing at the second timing. At this time, the scanning control unit 133 causes the beam transmission unit 111 to transmit the same SSB beam at the azimuth where the SSB beam was transmitted at the first timing also at the second timing.

[0037] Specifically, in the case of the example shown in FIG. 2, the sweeping control unit 133 causes the beam transmission unit 111 to transmit the SSB beam transmitted by the beam transmission unit 111 in time slot SSB#1 also in time slot SSB#2. By operating in this way, 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, so the signal-to-noise ratio is improved.

[0038] The sweeping control unit 133 may control the beam transmission unit 111 to transmit a radio station beam including first application data at a first timing and transmit a radio station beam including second application data different from the first application data at a second timing. The first application data is, for example, data included in an SSB beam, and the second application data is data included in a PDCCH (Physical Downlink Control Channel), a CDSCH (Physical Downlink Shared Channel), or a CSI-RS (Channel Status Information Reference Signal) beam. By operating in this way, the transmission timing of the SSB beam that does not contribute to the communication between the radio station 1 and the wireless terminal 2 is effectively utilized, and the substantial communication capacity in the wireless communication system S increases.

[0039] The sweeping control unit 133 may set the second timing when the radio station beam is not transmitted to the timing when the terminal beam is received from the wireless terminal 2. In this case, the sweeping control unit 133 controls the beam reception unit 112 to receive the terminal beam transmitted from the wireless terminal at the second timing.

[0040] In order to enable the wireless terminal 2 to transmit a terminal beam at a second timing, the scanning control unit 133 may transmit information indicating the second timing at which the terminal beam can be transmitted to the wireless terminal 2 via the communication unit 11 or via another communication medium such as Wi-Fi (registered trademark). The information indicating the second timing is, for example, a time slot number. By operating the scanning control unit 133 in this way, the uplink communication capacity can be increased.

[0041] [Flow of processing of the wireless station 1] FIG. 5 is a flowchart showing the flow of processing of the wireless station 1. The flowchart shown in FIG. 5 starts from the point in time when the wireless station 1 starts operating.

[0042] First, the scanning control unit 133 controls the beam transmission unit 111 to transmit a wireless station beam at the initially set timing (S1). The initially set timing is all the timings at which the wireless station beam can be transmitted.

[0043] Subsequently, the azimuth estimation unit 131 estimates the azimuth of the wireless terminal 2 based on the azimuth at which the terminal beam is received from the wireless terminal 2 (S2). The range determination unit 132 determines a terminal azimuth range, which is the range of the azimuth where the terminals exist, based on the azimuths of the plurality of wireless terminals 2 estimated by the azimuth estimation unit 131 (S3). The range determination unit 132 notifies the scanning control unit 133 that the terminal azimuth range has been determined. Further, the range determination unit 132 stores the determined terminal azimuth range in the storage unit 12.

[0044] When the sweeping control unit 133 receives a notification from the range determination unit 132 that the terminal azimuth range has been determined, it compares the terminal azimuth range stored in the storage unit 12 with the determined terminal azimuth range (S4). When the sweeping control unit 133 determines that the terminal azimuth range has been changed (YES in S4), it changes the timing of transmitting the radio station beam (S5). Specifically, the sweeping control unit 133 excludes the timing corresponding to the azimuth not included in the terminal azimuth range from the timing of transmitting the radio station beam. When the sweeping control unit 133 determines that the terminal azimuth range has not been changed (NO in S4), it does not change the timing of transmitting the radio station beam.

[0045] The control unit 13 repeats the processes from S2 to S5 until it receives an operation to end the operation of transmitting the radio station beam (NO in S6).

[0046] [Effect of the radio station 1 according to the first embodiment] As described above, the radio station 1 includes an azimuth estimation unit 131 that estimates one or more azimuths corresponding to one or more wireless terminals 2, a range determination unit 132 that determines a terminal azimuth range including the one or more azimuths estimated by the azimuth estimation unit 131, and a sweeping control unit 133 that controls the beam transmission unit 111 to transmit a radio station beam at one or more first timings corresponding to the one or more azimuths included in the terminal azimuth range and not to transmit a radio station beam at one or more second timings corresponding to a range outside the terminal azimuth range. Since the radio station 1 is configured in this way, the beam transmission unit 111 does not transmit a radio station beam (for example, an SSB beam) at a timing corresponding to an azimuth where the wireless terminal 2 does not exist, so that it is possible to prevent the consumption of useless resources that do not contribute to the communication between the radio station 1 and the wireless terminal 2.

[0047] <Second Embodiment> FIG. 6 is a diagram showing the configuration of the radio station 1A according to the second embodiment. In the radio station 1 according to the first embodiment, the azimuth estimated by the azimuth estimation unit 131 when the wireless terminal 2 exists is used as the terminal azimuth range, but an error may occur in the azimuth estimated by the azimuth estimation unit 131. Therefore, the radio station 1A is characterized in that it determines the terminal azimuth range in consideration of the error.

[0048] As shown in FIG. 6, the wireless station 1A is different from the wireless station 1 shown in FIG. 4 in that the control unit 13 further includes a moving speed specifying unit 134 and a calculating unit 135, and is the same in other respects. Hereinafter, the description will focus on the differences from the wireless station 1.

[0049] The moving speed specifying unit 134 specifies the moving speed of the wireless terminal 2 at a plurality of time points based on the relationship between the plurality of azimuths and the plurality of times at which the wireless terminal 2 existed, which were estimated by the azimuth estimating unit 131 at a plurality of times and stored in the storage unit 12. Specifically, the moving speed specifying unit 134 calculates the moving speed with respect to other wireless stations using the following formula (2).

[0050]

Equation

[0051] In this case, the azimuth estimating unit 131 estimates the azimuth at the next time by the following formula (3).

Equation

[0052] The calculating unit 135 calculates a variation value indicating the magnitude of the variation of the plurality of moving speeds corresponding to the plurality of time points. The variation value is represented by a statistical value such as, for example, the variance or standard deviation of the moving speed.

[0053] The calculating unit 135 calculates the standard deviation as the variation value by, for example, the following formula (4).

Equation

[0054] Based on the azimuth of the wireless terminal 2 immediately before, the moving speed specified by the moving speed specifying unit 134, and the variation value, the range determining unit 132 estimates the terminal azimuth range of the wireless terminal 2 at the next moment. For example, based on the azimuth of the wireless terminal 2 immediately before and the latest moving speed specified by the moving speed specifying unit 134, the range determining unit 132 estimates the positions of other wireless stations at the next moment, and based on the position to be estimated and the variation value, calculates a terminal azimuth range considering errors.

[0055] Specifically, the range determining unit 132 estimates the range of errors in the azimuth of other wireless stations at the next moment, for example, by the following formula (5). [Equation] The range determining unit 132 determines a terminal azimuth range considering errors by adding the range of errors calculated by formula (5) to the azimuth at the next moment calculated by formula (3). The range determining unit 132 notifies the determined terminal azimuth range to the sweep control unit 133. Based on the notified terminal azimuth range, the sweep control unit 133 controls the beam transmission unit 111 and the beam reception unit 112 in the same manner as the wireless station 1 in the first embodiment.

[0056] [Effect of the wireless station 1A according to the second embodiment] As described above, the sweep control unit 133 of the wireless station 1A estimates the azimuth of the wireless terminal 2 at the next moment, and controls the communication unit 11 using the terminal azimuth range taking into account the errors included in the estimated azimuth. With the wireless station 1A configured in this way, even when the wireless terminal 2 moves, the wireless station 1A can transmit a wireless station beam at the timing corresponding to the azimuth where the wireless terminal 2 exists, and not transmit a wireless station beam at the timing corresponding to the azimuth where the wireless terminal 2 does not exist.

[0057] In addition, according to the present invention, it becomes possible to contribute to Goal 9, "Build the infrastructure for industry and technological innovation," of the Sustainable Development Goals (SDGs) led by the United Nations.

[0058] As described above, the present invention has been described using embodiments. However, 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. For example, all or part of the device can be configured by being functionally or physically dispersed and integrated in any unit. Also, new embodiments resulting from any combination of a plurality of embodiments are included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination have the effects of the original embodiments combined.

Explanation of Reference Numerals

[0059] 1 Wireless station 2 Wireless terminal 11 Communication unit 12 Storage unit 13 Control unit 111 Beam transmission unit 112 Beam reception unit 131 Azimuth estimation unit 132 Range determination unit 133 Scanning control unit 134 Moving speed identification unit 135 Calculation unit

Claims

1. A beam transmission unit that transmits a radio station beam toward one or more radio terminals while changing the azimuth at a predetermined period; A beam reception unit that receives a terminal beam from the one or more radio terminals after the beam transmission unit transmits the radio station beam; An azimuth estimation unit that estimates one or more azimuths corresponding to the one or more radio terminals; A range determination unit that determines a terminal azimuth range including the one or more azimuths estimated by the azimuth estimation unit; A sweep control unit that controls the beam transmission unit to transmit the radio station beam at one or more first timings corresponding to one or more azimuths included in the terminal azimuth range, and not to transmit the radio station beam at one or more second timings corresponding to ranges outside the terminal azimuth range; A radio station having the above.

2. The sweep control unit controls the beam reception unit to receive the terminal beam transmitted from the radio terminal at the second timing. The radio station according to Claim 1.

3. Further comprising a storage unit that stores the azimuth of the radio terminal in association with time, The sweep control unit controls the beam transmission unit to transmit the radio station beam to a range excluding the azimuth of the radio terminal not stored in the storage unit over a predetermined period. The radio station according to Claim 1.

4. A moving speed specifying unit that specifies the moving speed of the radio terminal with respect to the radio station; A calculation unit that calculates a variation value indicating the magnitude of the variations of the plurality of moving speeds corresponding to a plurality of time points; A specifying unit that specifies the terminal azimuth range at the next time based on the azimuth of the terminal beam most recently received by the beam reception unit from the radio terminal, the moving speed, and the variation value; Further comprising the above. The radio station according to any one of Claims 1 to 3.

5. Steps executed by a computer, Transmitting, to a beam transmission unit, a radio station beam toward one or more radio terminals while changing the azimuth at a predetermined period; Receiving a terminal beam from the radio terminal after transmitting the radio station beam; Estimating one or more azimuths corresponding to the one or more radio terminals; Determining a terminal azimuth range including the one or more estimated azimuths; Controlling the beam transmission unit to transmit the wireless station beam at one or more first timings corresponding to one or more azimuths included in the terminal azimuth range, and not to transmit the wireless station beam at one or more second timings corresponding to a range outside the terminal azimuth range; A communication method having the above.

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