JP7565892B2 - Base station device, terminal device, control method, and program for selecting beams to be used for communication - Google Patents

Description

The present invention relates to relay transmission technology in wireless communication.

In mobile communications, wireless repeaters are used to expand the communication area. By amplifying the signals they receive (and converting the frequency if necessary) and sending them out, wireless repeaters can, for example, allow signals sent by a base station device to reach areas farther away or in the shadows of buildings, which are difficult for radio waves to reach.

A base station device can generally be configured to form multiple beams to provide terminal devices within the area with sufficiently high-speed communication services. In this case, the wireless repeater receives and transmits a signal transmitted by one of the multiple beams formed by the base station device. On the other hand, in this case, if the wireless repeater relays using an omnidirectional antenna, the area expansion effect may be insufficient due to insufficient relaying gain. For this reason, it is expected that the wireless repeater will form multiple beams each facing in a different direction to relay signals.

As described above, when a wireless repeater can form multiple beams and transmit radio waves, it is important to efficiently identify and use a beam suitable for relaying communications of a terminal device. In addition, depending on the location of the terminal device, it may be possible to obtain better communication quality when communicating directly using a beam formed by a base station device than when using a wireless repeater. For this reason, it is also important to decide whether or not to involve a relay device in communications between a base station device and a terminal device.

The present invention provides a technology for efficiently identifying a beam to be used for communication by a terminal device in a wireless communication system including a base station device and a relay device, each capable of forming multiple beams.

A base station device according to one aspect of the present invention is a base station device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, and the base station device has a notification means for notifying the terminal device of information specifying a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the reference signal is not relayed , and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams, an instruction means for instructing the relay device by transmitting a control signal that the relay device should discontinue relaying in the first period and perform relaying in the second period, and a transmission means for transmitting the reference signal in the first period and the second period.

A terminal device according to one aspect of the present invention is a terminal device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, and includes a receiving means for receiving information from the base station device that specifies a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the relay device does not relay the reference signal, and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams, a measuring means for measuring the reference signal in the first period based on the information, and omitting measurement of the reference signal in the second period when the wireless quality of the reference signal transmitted in any of the first plurality of beams in the first period exceeds a predetermined quality, and a transmitting means for transmitting the result of the measurement to the base station device.

According to the present invention, in a wireless communication system including a base station device and a relay device, each capable of forming multiple beams, it is possible to efficiently identify the beam to be used for communication with a terminal device.

FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. FIG. 13 is a diagram illustrating an example of measurement in a first period. FIG. 13 is a diagram illustrating an example of measurement in a second period. FIG. 13 is a diagram illustrating an example of measurement in a third period. FIG. 13 is a diagram illustrating an example of a beam to be measured in a second period. 2 is a diagram illustrating an example of the hardware configuration of a base station device, a relay device, and a terminal device. FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. FIG. 2 illustrates an example of a functional configuration of a relay device. FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. FIG. 1 is a diagram illustrating a first example of processing executed in a wireless communication system. FIG. 11 is a diagram illustrating a second example of a process executed in a wireless communication system. FIG. 11 is a diagram illustrating a third example of a process executed in a wireless communication system. FIG. 11 is a diagram illustrating a fourth example of processing executed in the wireless communication system.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any combination. In addition, the same reference numbers are used for the same or similar configurations, and duplicate descriptions are omitted.

(Configuration of communication system)
FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system is a relay communication system in which a relay device 121 relays communication between a base station device 101 and a terminal device 141. In this wireless communication system, the base station device 101 forms multiple beams 111 to 113 to transmit signals, and the relay device 121 relays a signal received via any one of these beams. Note that the relay device 121 can set multiple beams 131 to 132 using, for example, multiple antennas, and can output a received signal toward at least any one of the multiple beams 131 to 132. The terminal device 141 connects to the base station device 101 and communicates via any one of the multiple beams 111 to 113 formed by the base station device 101 and the multiple beams 131 to 132 formed by the relay device 121. Note that, in one example, the relay device 121 is a wireless repeater, and is configured to amplify and output a received signal. The relay device 121 simply forwards signals between the base station device 101 and the terminal device 141 without performing decoding processing on the user data, and therefore the base station device 101 and the terminal device 141 can perform the same communication processing as if they were directly connected to each other.

Here, since the relay device 121 relays the signal transmitted from the base station device 101 as it is, the terminal device 141 cannot recognize whether the relay device 121 is involved when receiving the signal. Furthermore, the terminal device 141 cannot recognize which of the beams 131 to 132 formed by the relay device 121 has relayed the received signal. Therefore, it cannot specify whether the communication between the base station device 101 and the terminal device 141 should be performed via the relay device 121, or which of the multiple beams 131 to 132 should be used when communicating via the relay device 121. In response to this, for example, the base station device 101 can transmit reference signals generated based on different sequences for each combination of the beams 111 to 113 formed by the base station device 101 and the beams 131 to 132 formed by the relay device 121. That is, in the example of FIG. 1, for six possible beam combinations consisting of three beams 111-113 formed by the base station device 101 and two beams 131-132 formed by the relay device 121, a reference signal is generated using a different sequence for each combination, and the reference signal is transmitted using the corresponding beam combination.

Also, for example, a reference signal generated based on a different sequence is transmitted in each of the beams 111 to 113 formed by the base station device 101, and a period is provided in which the reference signal is not relayed by the relay device 121, and the terminal device 141 observes the reference signal transmitted from the beams 111 to 113 during that period. That is, a first period (time interval) in which the base station device 101 transmits a reference signal in each of the multiple beams and the relay device 121 does not relay it, and a second period in which the reference signal is transmitted in the multiple beams of the base station device 101 and relayed in the multiple beams of the relay device 121 may be provided. According to this, the terminal device 141 may receive the reference signal transmitted in each of the multiple beams formed by the base station device 101 during the first period and measure the radio quality of each (for example, reference signal received power (RSRP) or reference signal received quality (RSRQ)). Then, the terminal device 141 may receive a reference signal that is transmitted by each of the multiple beams formed by the base station device 101 and relayed by each of the multiple beams formed by the relay device 121 during the second period, and measure the wireless quality for each combination of beams. This allows the terminal device 141 to determine which of the wireless quality is better: when communicating directly with the base station device 101 via one of the multiple beams formed by the base station device 101, or when communicating via the relay device 121. Furthermore, when communicating via the relay device 121, the terminal device 141 may determine a combination of the beams formed by the base station device 101 and the beams formed by the relay device 121 that is suitable for use in communication, based on the sequence used to generate the reference signal.

Here, an example of the flow of reference signal transmission in the first period will be described using FIG. 2, and an example of the flow of reference signal transmission in the second period will be described using FIG. 3. In FIG. 2 and FIG. 3, the beam in which the reference signal is transmitted in the base station device 101 and the beam in which the signal is relayed in the relay device 121 are indicated by solid thick lines. In addition, the beam that the base station device 101 can form and that does not transmit the reference signal and the beam that the relay device 121 can form and that does not relay the signal are indicated by dashed thin lines.

As shown in FIG. 2, in the first period, the base station device 101 transmits a reference signal while switching between multiple formable beams 111 to 113 over time. The reference signal is generated based on mutually different sequences that are assigned separately to each beam. This allows the terminal device 141 to identify which beam transmitted the reference signal when it receives the reference signal. In the first period, the relay device 121 is in a state where relaying is not performed. In order to form such a state, the base station device 101 of this embodiment is configured to be able to specify the first period and transmit a control signal including an instruction to cause the relay device 121 to suspend relaying of the signal. Similarly, the relay device 121 is configured to be able to receive a control signal from the base station device 101, and is configured to stop relaying the communication of the base station device 101 in the first period based on the control signal. In this way, by stopping relaying in the relay device 121, it is possible to ensure that the reference signal that arrives at the terminal device 141 in the first period is one that arrives directly from the base station device 101. As a result, it is possible to measure with high accuracy the wireless quality when direct communication is performed between the terminal device 141 and the base station device 101 using the beam formed by the base station device 101.

On the other hand, as shown in FIG. 3, in the second period, the relay device 121 performs relaying. For example, the base station device 101 transmits a reference signal with the first beam 111, and relays the reference signal while switching over time among the beams 131 to 132 that the relay device 121 can form. After that, the base station device 101 switches from the first beam 111 to the second beam 112 or the third beam 113 to transmit a reference signal, and relays the reference signal while switching over time among the beams 131 to 132 that the relay device 121 can form. In one example, the base station device 101 generates a reference signal based on a different sequence for each combination of the first multiple beams formed by the base station device 101 and the second multiple beams formed by the relay device 121, and transmits a corresponding reference signal at the timing when each combination of beams is used. According to this, when the terminal device 141 receives a reference signal, it can identify which of the combinations of the first multiple beams formed by the base station device 101 and the second multiple beams formed by the relay device 121 the reference signal was transmitted from. Note that the sequence used to generate the signal transmitted in the first period and the sequence used to generate the signal transmitted in the second period may overlap at least in part, or may be selected so as not to overlap with each other. This is because even if the same sequence is used in the first period and the second period, the terminal device 141 can identify whether or not the signal has reached the terminal device 141 via the relay device 121 due to the difference in the periods.

In this way, the terminal device 141 can measure the wireless quality when communicating directly with the base station device 101 and when communicating via the relay device 121, and the base station device 101 can determine the beam to be used for communication with the terminal device 141 based on the wireless quality measurement results. In one example, the base station device 101 can determine to use a combination of beams 111 and 132 for communication with the terminal device 141, and can transmit a control signal to the relay device 121 to cause the relay device 121 to use beam 132 when actually communicating with the terminal device 141.

On the other hand, as shown in FIG. 3, when measurements are performed for each combination of multiple beams, the processing load for the measurement in the terminal device 141 may be large. That is, when the number of beams that can be formed by the base station device 101 is M and the number of beams that can be formed by the relay device 121 is N, in the measurement in FIG. 3, the terminal device 141 needs to observe M×N reference signals and calculate their wireless quality. Furthermore, the terminal device 141 needs to measure M reference signals and calculate their wireless quality in the first period as shown in FIG. 2. That is, in the above-mentioned processing, the terminal device 141 needs to measure M+M×N reference signals and calculate their wireless quality. In the examples shown in FIG. 2 and FIG. 3, M=3 and N=2, so the processing load may not be high, but the number of beams that the base station device 101 can form is generally large, and it is also expected that the number of beams that the relay device 121 can form will be large. For this reason, it is important to reduce the processing load related to the measurement of signals received in the terminal device 141.

In this embodiment, as an example, when the terminal device 141 directly receives the reference signal transmitted by the multiple beams 111 to 113 of the base station device 101 during the first period and measures the wireless quality, if the wireless quality of the reference signal transmitted by any of the beams exceeds a predetermined wireless quality, the measurement process of the wireless quality during the second period is omitted. That is, when the terminal device 141 directly receives a signal transmitted from the base station device 101, if the wireless quality of the signal is sufficiently good, the measurement of the reference signal via the relay device 121 is not performed. According to this, it is sufficient to measure the reference signal and calculate the wireless quality for the number of beams that the base station device 101 can form, so that the processing load on the terminal device 141 can be significantly reduced. Note that, for this processing, the first period can be set as a period preceding the second period. Note that, when the first period and the second period are set repeatedly and the terminal device 141 repeatedly performs the wireless quality measurement process, the first period may be provided after the second period. In this case, the terminal device 141 performs the measurement process of wireless quality in the first arriving second period, but based on the measurement results in the subsequent first period, it is possible to omit the measurement process of wireless quality in the next arriving second period.

In addition, if the wireless quality of the reference signal from each of the multiple beams 111 to 113 of the base station device 101 does not exceed a predetermined wireless quality as a result of the measurement in the first period, the terminal device 141 may omit the measurement in the first period in the subsequent observation process. In other words, if the reference signal transmitted from the multiple beams 111 to 113 of the base station device 101 cannot be received with sufficient wireless quality, the terminal device 141 determines that communication via the relay device 121 is necessary, and thereafter performs the measurement process of the wireless quality only in the second period. This is effective when the first period and the second period are repeatedly provided and the terminal device 141 performs the measurement repeatedly. In other words, the terminal device 141 performs the measurement process of the wireless quality in the first period that arrives first, but can omit the measurement process of the wireless quality in the next first period that arrives based on the measurement result of the first period. For example, if the number of repetitions of the wireless quality measurement process is L, if the wireless quality measurement process in the first period is not omitted, the wireless quality measurement process is performed L x (M + M x N) times, but if the wireless quality measurement process in the first period is omitted, it is sufficient to perform the wireless quality measurement process M + L x M x N times.

In this way, the terminal device 141 can omit a part of the subsequent measurement process depending on the measurement results of the reference signals from the multiple beams 111 to 113 of the base station device 101, and can reduce the processing load of the measurement process of the wireless quality. Note that, if the wireless quality of the reference signal from any of the beams 111 to 113 in the first period exceeds a first predetermined quality, the terminal device 141 may omit the measurement process of the wireless quality in the second period, if the wireless quality of the reference signal from each of the beams 111 to 113 in the first period does not exceed a second predetermined quality that is lower than the first predetermined quality, the terminal device 141 may omit the measurement process of the wireless quality in the first period thereafter, and otherwise perform the measurement process of the wireless quality in both the first period and the second period. That is, if the wireless quality when communicating directly with the base station device 101 is not sufficiently high, the wireless quality when the terminal device 141 communicates via the relay device 121 may also be measured, and depending on the measurement result, it may be determined whether direct communication should be performed between the base station device 101 and the terminal device 141, or whether communication should be performed between the base station device 101 and the terminal device 141 via the relay device 121.

In addition, the base station device 101 notifies the terminal device 141 of information designating the first period and the second period in order to cause the terminal device 141 to execute this process. In addition, in one example, the base station device 101 may be configured to control the relay device 121 so that the relay device 121 does not relay signals from the base station device 101 in the first period and relays signals from the base station device 101 in the second period. For example, the base station device 101 may notify the relay device 121 of information designating the first period and instructing the relay device 121 to stop relaying. In addition, the setting of the relay device 121 may be determined in advance, and in this case, the base station device 101 may be configured not to perform the setting. The base station device 101 transmits reference signals (e.g., cell-specific reference signals) sequentially using each of the formable beams 111 to 113 in the first period and the second period. When the terminal device 141 acquires information specifying the first and second periods, it measures the reference signal in at least the first period, and depending on the measurement results, omits measurements in the second period or subsequent measurements in the first period as necessary, as described above.

In the above example, the terminal device 141 has been described as omitting part of the subsequent wireless quality measurement process in accordance with the measurement results of the reference signals transmitted in each of the multiple beams 111 to 113 of the base station device 101. Note that other processes may be used to omit part of the wireless quality measurement process. For example, such a process may be performed by enabling the relay device 121 to transmit a reference signal independently.

In this case, in addition to the first and second periods as described above, a third period is set in which the relay device 121 transmits a second reference signal generated by itself (i.e., not the first reference signal arriving from the base station device 101). The base station device 101 notifies the terminal device 141 of information specifying the third period in addition to the first and second periods, and the base station device 101 may transmit the first reference signal in the first and second periods and not transmit the first reference signal in the third period. Note that in the third period, the relay device 121 may transmit the second reference signal without relaying the first reference signal, and the base station device 101 may continue to transmit the first reference signal. However, in this case, the first reference signal and the second reference signal are configured to be generated based on different sequences so that they can be distinguished. The base station device 101 may be configured to control the relay device 121 to perform each operation. That is, under the control of the base station device 101, the relay device 121 may be configured not to relay a signal from the base station device 101 in the first period, to relay a signal from the base station device 101 in the second period, and to independently generate and transmit a second reference signal in the third period. In one example, the base station device 101 may notify the relay device 121 of information indicating at least the first period and the third period. The base station device 101 may also notify the relay device 121 of information indicating the second period. Note that the relay device 121 does not need to be controlled by the base station device 101, for example, by having the control in the first period, the second period, and the third period set in advance by a network operator or the like.

Here, an example of the flow of reference signal transmission in the third period will be described with reference to FIG. 4. As shown in FIG. 4, in the third period, the relay device 121 transmits a second reference signal different from the first reference signal transmitted by the base station device 101 while switching over the multiple beams 131 to 132 that can be formed over time. At this time, the base station device 101 may stop transmitting the first reference signal. As described above, the base station device 101 may continue transmitting the first reference signal, but the relay device 121 may be configured to transmit the second reference signal without relaying the first reference signal. In some cases, the relay device 121 may be configured to transmit the second reference signal while relaying the first reference signal. The second reference signal is generated based on different sequences for each of the multiple beams 131 to 132, and is configured to be able to identify which beam was used to transmit the second reference signal when the terminal device 141 receives the second reference signal. The second reference signal may be generated based on a sequence different from that of the first reference signal, or may be transmitted in a format that can be distinguished from the first reference signal, such as by being transmitted in a radio resource (for example, a different resource element in a resource block) different from that of the first reference signal. If the first reference signal is not transmitted in the third period, the first reference signal and the second reference signal are distinguished by their transmission timing, so the second reference signal may be generated based on the same sequence as a part of the first reference signal and transmitted in the same resource element as the resource element in which the first reference signal is placed in the resource block. By setting this third period, the terminal device 141 can determine whether or not good wireless quality can be achieved in communication via the relay device 121.

The terminal device 141 acquires information indicating a third period from the base station device 101 in addition to the information indicating the first and second periods described above. Then, the terminal device 141 receives a second reference signal transmitted from the relay device 121 during the third period, and restricts the measurement process of the wireless quality based on the reference signal during the first and second periods based on the reception result.

For example, if the radio quality of the second reference signal transmitted from each of the multiple beams 131 to 132 of the relay device 121 during the third period does not exceed a predetermined quality, the terminal device 141 may not perform measurements during the second period. Then, the terminal device 141 may measure the first reference signal transmitted from each of the multiple beams 111 to 113 of the base station device 101 during the first period and perform measurements for direct communication with the base station device 101. Then, the terminal device 141 may notify the base station device 101 of the measurement results of the beams 111 to 113, for example, and the base station device 101 may determine the beam to be used for communication with the terminal device 141 based on the notification. According to this, when the number of beams formed by the base station device 101 is M and the number of beams formed by the relay device 121 is N, the measurement process of the wireless quality for the combination of M × N beams in the second period is omitted, and the measurement process of the wireless quality based on the reference signal is performed only for the M + N beams in the first period and the second period.

In addition, if the wireless quality of the second reference signal transmitted from one of the multiple beams 131-132 of the relay device 121 during the third period exceeds a predetermined quality, the terminal device 141 may perform measurement during the second period. In this case, the terminal device 141 performs wireless quality measurement processing only for beams of the relay device 121 whose corresponding wireless quality exceeds the predetermined quality. For example, if the wireless quality of beam 132 of the relay device 121 exceeds the predetermined quality, then, among the combinations of the beams of the base station device 101 and the beams of the relay device 121 that transmit the reference signal during the second period, only the combination in which beam 132 is used is the subject of measurement. This is shown in FIG. 5.

The terminal device 141 measures the wireless quality based on the second reference signal transmitted by the beams 131-132 transmitted as shown in FIG. 4, and when it is determined that the wireless quality of the beam 132 exceeds a predetermined quality, it measures the wireless quality based on the first reference signal transmitted from the base station device 101 and relayed by the relay device 121 only when the beam 132 is used, as shown in FIG. 5. In FIG. 5, the combination of beams to be measured is indicated by a thick dotted line. As shown in FIG. 5, the terminal device 141 may omit the measurement process of the wireless quality for the combination of beams in which the beam 131 is used in the second period. In this case, it is sufficient to perform only M measurements for the beam of the relay device 121 in the third period and N measurements resulting from the relay device 121 being limited to one beam for the beams of the base station device 101 and the beams of the relay device 121 in the second period, so that only M+N measurements of wireless quality are performed. The terminal device 141 does not have to specify only one of the beams of the relay device 121 based on the measurement in the third period. By specifying some of the multiple beams that the relay device 121 can form, the processing load related to the measurement in the terminal device 141 can be reduced. For example, if there is no beam whose corresponding wireless quality exceeds a predetermined quality in the third period, the terminal device 141 may select one beam with the best wireless quality and perform the measurement in the second period. If the wireless quality of the reference signal transmitted in any of the beams 131 to 132 that the relay device 121 can form exceeds a predetermined quality in the third period, the terminal device 141 may not perform the measurement of the first reference signal transmitted in the multiple beams 111 to 113 of the base station device 101 in the first period. That is, in a situation where it can be determined that sufficient quality is guaranteed by communication via the relay device 121, the terminal device 141 may determine not to communicate directly with the base station device 101.

In one example, in order to efficiently omit the above-mentioned processing, the third period may be set prior to the first period and the second period. However, this is not limited to this, and the third period may be set after the first period or the second period. In one example, the third period may be set after the first period, and the second period may be set after that. Furthermore, if the first period to the third period are set periodically and the terminal device 141 performs wireless quality measurement processing during those periods, the third period may be set after the second period.

Control using multiple thresholds may also be performed. For example, when the wireless quality of the second reference signal transmitted in any of the multiple beams 131 to 132 of the relay device 121 during the third period exceeds the first predetermined quality, the terminal device 141 performs a measurement process of the wireless quality for the combination in which the beam exceeding the first predetermined quality is used during the second period, and omits the processing for the other combinations. On the other hand, when none of the second reference signals transmitted in each of the multiple beams 131 to 132 of the relay device 121 during the third period exceeds a second predetermined quality that is lower than the first predetermined quality, the terminal device 141 determines that the quality of communication via the relay device 121 cannot be guaranteed, and may not perform the measurement process of the wireless quality during the second period. Then, when the wireless quality of the second reference signal transmitted by any of the multiple beams 131-132 of the relay device 121 in the third period exceeds the second predetermined quality and none of the second reference signals exceeds the first predetermined quality, the terminal device 141 can perform a wireless quality measurement process in the first period and the second period. This makes it possible to perform communication between the base station device 101 and the terminal device 141 by either direct communication with the base station device 101 or communication via the relay device 121, whichever is better in wireless quality. In addition, if the wireless quality of the second reference signal transmitted by any of the multiple beams 131-132 of the relay device 121 during the third period exceeds the second predetermined quality, and none of the second reference signals exceeds the first predetermined quality, the terminal device 141 may perform measurements during the second period for beam combinations that use one or more beams for which the second reference signal exceeds the second predetermined quality, and may omit measurements for other beam combinations.

(Device configuration)
Using FIG. 6, an example of the hardware configuration of the base station device 101, the relay device 121, and the terminal device 141 will be described. In one example, each device is configured to include a processor 601, a ROM 602, a RAM 603, a storage device 604, and a communication circuit 605. The processor 601 is a computer configured to include one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the device and each of the above-mentioned processes by reading and executing a program stored in the ROM 602 or the storage device 604. The ROM 602 is a read-only memory that stores information such as programs and various parameters related to the processing executed by each device. The RAM 603 functions as a workspace when the processor 601 executes a program, and is a random access memory that stores temporary information. The storage device 604 is configured, for example, by a removable external storage device. The communication circuit 605 is configured to include, for example, a circuit for wireless communication of LTE or 5G. Although one communication circuit 605 is illustrated in FIG. 6, each device may have multiple communication circuits.

Next, examples of the functional configurations of the base station device 101, relay device 121, and terminal device 141 will be described. Each device is configured to execute the above-mentioned processes and has the corresponding functions. Below, only an overview of each function will be given, and the contents described above will not be repeated.

Figure 7 shows an example configuration of the base station device 101. The base station device 101 is configured to include, as an example of its functional configuration, a period setting notification unit 701, a relay device control unit 702, a reference signal transmission unit 703, a report reception unit 704, and a beam to be used determination unit 705. Note that these functions can be realized, for example, by the processor 601 executing a program stored in the ROM 602 or the like. However, this is not limited to the above, and at least some of the functions may be realized by dedicated hardware.

The period setting notification unit 701 notifies the terminal device 141 of information indicating the above-mentioned first period and second period, and information indicating the third period when the relay device 121 transmits its own reference signal. The relay device control unit 702 controls the operation of the relay device 121, for example, by notifying the relay device 121 that relaying will be stopped in the first period. The relay device control unit 702 can also instruct the relay device 121 to generate and transmit a reference signal independently in the third period by notifying the relay device 121 of information indicating the third period. The reference signal transmission unit 703 generates a reference signal at least in the first period and the second period and transmits it by each of the multiple beams that the base station device 101 can form. Note that the reference signal transmission unit 703 can generate a reference signal using a different sequence for each of the multiple beams that the base station device 101 can form, and transmit the reference signal by the corresponding beam. The reference signal transmitting unit 703 may transmit a reference signal by switching beams over time, as described above. However, without being limited thereto, the reference signal transmitting unit 703 may transmit corresponding reference signals in parallel (simultaneously) in two or more beams among a plurality of beams that the base station device 101 can form. The report receiving unit 704 acquires information indicating the measurement results of the wireless quality in each period from the terminal device 141 to which the information of the first period to the third period has been notified by the period setting notification unit 701. Note that this information may include, for example, information in which information indicating the wireless quality is associated with information indicating which sequence the wireless quality corresponds to. In addition, this information may be, for example, information indicating which sequence a reference signal received exceeding a predetermined wireless quality is based on. This information may have any other format capable of determining which beam to use for communication with the terminal device 141. The used beam determining unit 705 determines the beam to use for communication with the terminal device 141 based on the information received by the report receiving unit 704. The beam-to-beam determination unit 705 then uses the determined beam to communicate with the terminal device 141.

Figure 8 shows an example configuration of relay device 121. As an example of its functional configuration, relay device 121 includes, for example, a relay processing unit 801 and a relay stopping unit 802, and further includes a reference signal transmitting unit 803 as necessary. Note that these functions can be realized, for example, by processor 601 executing a program stored in ROM 602 or the like. However, this is not limited to the above, and at least some of the functions may be realized by dedicated hardware.

The relay processing unit 801 amplifies and relays a signal transmitted from the base station device 101 by non-regenerative relay that does not involve at least decoding of user data. The relay processing unit 801 is configured to transmit a received signal from multiple antennas, for example, and is configured to form beams in multiple directions and transmit radio waves by multiplying the signals output from each of the multiple antennas by a predetermined weighting coefficient (amplifying/attenuating and shifting the phase). The relay processing unit 801 amplifies (and, in some cases, converts the frequency of) the radio signal received from the base station device 101 and transmits it using at least one of multiple beams that can be formed. The relay stop unit 802 controls the relay processing unit 801 to stop relaying, for example, under the control of the base station device 101. For example, when the relay stop unit 802 receives information specifying a first period from the base station device 101, it controls the relay processing unit 801 to stop relaying the signal from the base station device 101 during the first period. For example, in the first period, the relay processing unit 802 may prevent a signal input from a receiving antenna from being input to the relay processing unit 801, or may prevent a signal amplified by the relay processing unit 801 from being sent from a transmitting antenna. When the above-mentioned third period is set, for example, the reference signal transmission unit 803 generates a reference signal using mutually different sequences corresponding to each of a plurality of beams that can be set in the relay device 121 during the third period, and transmits the reference signal using the corresponding beam. Note that relaying of a signal from the base station device 101 may be stopped during the third period in which the reference signal transmission unit 803 transmits a reference signal. In that case, the relay stop unit 802 may control the relay processing unit 801 to stop relaying during the third period.

Figure 9 shows an example of the configuration of the terminal device 141. As an example of its functional configuration, the terminal device 141 is configured to include, for example, a period information acquisition unit 901, a measurement processing unit 902, a measurement restriction unit 903, and a measurement result notification unit 904. Note that these functions can be realized, for example, by the processor 601 executing a program stored in the ROM 602 or the like. However, this is not limited to the above, and at least some of the functions may be realized by dedicated hardware.

The period information acquisition unit 901 acquires information on the above-mentioned first and second periods, and if a third period is set, also acquires information on the third period. The measurement processing unit 902 performs measurement processing of wireless quality based on the reference signal in each of the first to third periods. As described above, the measurement restriction unit 903 restricts the measurement processing of wireless quality based on the measurement results in the first and third periods, for example, and performs processing to reduce the load on the measurement processing unit 902. The measurement result notification unit 904 provides the base station device 101 with a report based on the wireless quality measured by the measurement processing unit 902, enabling the base station device 101 to identify the beam to be used for communication with the terminal device 141.

(Processing flow)
Next, an example of the flow of processing executed in the wireless communication system will be described. The example of processing shown below is an example of a typical flow of processing according to the present embodiment, and various modifications as described above are possible, but the details will not be repeated here.

Figure 10 shows a first processing example. This processing example shows an example in which the first period and the second period are set, and the third period is not set. In this processing example, first, the base station device 101 notifies the terminal device 141 of the setting of the first period and the second period (S1001). Also, when the base station device 101 controls the relay device 121, the base station device 101 notifies the relay device 121 of information indicating at least the first period (S1002). After that, during the first period, the relay device 121 stops relaying (S1003). Also, the base station device 101 transmits a reference signal generated based on a sequence corresponding to each of the multiple beams using the corresponding beam (S1004). The terminal device 141 measures this beam.

Here, it is assumed that the terminal device 141 has determined in S1004 that the wireless quality of the reference signal in any of the beams exceeds a predetermined quality. In this case, the terminal device 141 can determine that it is possible to perform communication of sufficiently high quality by direct communication with the base station device 101. For this reason, in the second period, the relay device 121 resumes relaying (S1005), and the relay device 121 relays the reference signal transmitted by the base station device 101 (S1006), but the terminal device 141 omits measuring the reference signal (S1007). This is because the terminal device 141 is able to communicate with sufficient wireless quality by directly communicating with the base station device 101 without going through the relay device 121, and therefore does not need to measure the wireless quality related to the communication via the relay device 121. In this way, the terminal device 141 of this processing example does not need to perform the measurement process of the wireless quality in the second period, and therefore the processing load related to the measurement process can be significantly reduced.

On the other hand, if there is no beam whose wireless quality of the corresponding reference signal exceeds a predetermined quality in S1004, the terminal device 141 performs wireless quality measurement in the second period as shown in FIG. 11. However, in this case, the terminal device 141 can determine that sufficient wireless quality cannot be obtained when communicating directly with the base station device 101. Therefore, the terminal device 141 omits wireless quality measurement in the first period that arrives thereafter (S1101). This makes it possible to reduce the processing load related to the measurement process.

Next, an example of the process flow when a third period is provided and the relay device 121 generates and transmits a reference signal on its own will be described with reference to Figs. 12 and 13. In this process, the base station device 101 first notifies the terminal device 141 of the setting of a third period in addition to the first and second periods (S1201). Furthermore, when the base station device 101 controls the relay device 121, the base station device 101 notifies the relay device 121 of information indicating at least the first and third periods (S1202). Note that, in this case, it is assumed that the third period is set first, and then the first and second periods are set.

The terminal device 141 receives reference signals transmitted from each of the multiple beams 131 to 132 of the relay device 121 during the third period (S1203). Here, it is assumed that the terminal device 141 has determined that the wireless quality of the reference signal from the beam 132 exceeds a predetermined quality, and that the wireless quality of the reference signal from the beam 131 does not exceed the predetermined quality. In this case, the terminal device 141 can obtain good wireless quality by communicating with the base station device 101 via the relay device 121, so there is no need to know the wireless quality related to direct communication with the base station device 101. Therefore, the terminal device 141 may omit measuring the reference signal transmitted directly from the base station device 101 during the first period (S1204). This allows the terminal device 141 to reduce the processing load of the measurement process of the reference signal. The terminal device 141 may perform measurement during the first period and determine whether good wireless quality can be obtained when directly communicating with the base station device 101. Furthermore, the terminal device 141 may omit measurements for beams 131 for which the wireless quality of the corresponding reference signal does not exceed a predetermined quality during the second period (S1205). This is because if the reference signal transmitted from the beam 131 cannot be received with sufficient wireless quality, it is expected that the reference signal relayed by the beam 131 also cannot be received with sufficient wireless quality. In this way, the terminal device 141 can reduce the number of measurement targets during the second period, and can reduce the processing load of the measurement process of the reference signal.

On the other hand, if the terminal device 141 determines that the wireless quality of the reference signals transmitted from beams 131 and 132 does not exceed a predetermined quality as a result of the measurement in the third period, the terminal device 141 performs measurement in the first period to identify the wireless quality when communicating directly with the base station device 101. On the other hand, the terminal device 141 can determine that sufficient wireless quality cannot be obtained through communication via the relay device 121, and therefore omits measurement of the reference signal involving relaying by the relay device 121 in the second period (S1301). In this way, the processing load of the reference signal measurement process can be significantly reduced.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the invention.

Claims (10)

A base station device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, the base station device comprising:
a notification means for notifying the terminal device of information designating a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the reference signal is not relayed , and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams;
an instruction means for instructing the relay device to suspend relaying during the first period and to perform relaying during the second period by transmitting a control signal;
a transmitting means for transmitting the reference signal during the first period and the second period;
A base station device comprising: 2. The base station apparatus according to claim 1 , wherein the notification means notifies the relay apparatus of information indicating the first period. The transmitting means is
transmitting the reference signal based on a different sequence in each of the first plurality of beams during the first period;
transmitting the reference signals based on different sequences in each combination of the first plurality of beams and the second plurality of beams during the second period;
3. The base station device according to claim 1, wherein the base station device is a base station . A terminal device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, the terminal device comprising:
a receiving means for receiving information from the base station device that specifies a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the relay device does not relay the reference signal, and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams;
a measurement means for measuring the reference signal in the first time period based on the information, and omitting measurement of the reference signal in the second time period when a radio quality of the reference signal transmitted by any one of the first plurality of beams in the first time period exceeds a predetermined quality;
a transmitting means for transmitting the result of the measurement to the base station device;
A terminal device comprising: The terminal device according to claim 4, characterized in that the measurement means performs measurement of the reference signal in the second period when the radio quality of none of the reference signals transmitted by each of the first plurality of beams in the first period exceeds the specified quality, and omits measurement of the reference signal in the first period thereafter. The measuring means is
omitting measurement of the reference signal in the second time period when a radio quality of the reference signal transmitted in any of the first plurality of beams in the first time period exceeds a first predetermined quality;
When any of the radio qualities of the reference signals transmitted by each of the first plurality of beams in the first time period does not exceed a second predetermined quality that is lower than the first predetermined quality, performing measurement of the reference signals in the second time period, and omitting measurement of the reference signals in the first time period thereafter;
when the radio quality of the reference signal transmitted in each of the first plurality of beams in the first period does not exceed the first predetermined quality and the radio quality of the reference signal transmitted in any of the first plurality of beams exceeds the second predetermined quality, performing measurement of the reference signal in the first period and the second period.
5. The terminal device according to claim 4 . A control method executed by a base station device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, comprising:
notifying the terminal device of information designating a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the reference signal is not relayed , and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams;
instructing the relay device to suspend relaying during the first period and to perform relaying during the second period by transmitting a control signal;
Transmitting the reference signal in the first period and the second period;
A control method comprising: A control method executed by a terminal device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, comprising:
receiving information from the base station device that designates a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the relay device does not relay the reference signal, and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams;
measuring the reference signal in the first time period based on the information, and omitting measurement of the reference signal in the second time period when a radio quality of the reference signal transmitted in any one of the first plurality of beams in the first time period exceeds a predetermined quality;
transmitting a result of the measurement to the base station device;
A control method comprising: A computer provided in a base station device in a wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data,
notifying the terminal device of information designating a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the reference signal is not relayed , and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams;
instructing the relay device to suspend relaying during the first period and to perform relaying during the second period by transmitting a control signal;
transmitting the reference signal during the first period and the second period;
Program for. A wireless communication system including a base station device, a terminal device, and a relay device capable of relaying at least a signal transmitted by the base station device to the terminal device without decoding user data, the terminal device being provided with a computer,
receiving, from the base station device, information designating a first period during which the base station device transmits a reference signal in each of a first plurality of beams and the relay device does not relay the reference signal, and a second period during which the base station device transmits the reference signal in each of the first plurality of beams and the relay device relays the reference signal in each of a second plurality of beams;
measuring the reference signal in the first time period based on the information, and omitting measurement of the reference signal in the second time period when a radio quality of the reference signal transmitted in any of the first plurality of beams in the first time period exceeds a predetermined quality;
transmitting the measurement result to the base station device;
Program for.

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