WO2025173212A1 - Terminal device and base station device - Google Patents

Abstract

The objective of the present invention is to improve the signal detection performance of a terminal device in a wireless communication system. The terminal device includes a first reception unit, a second reception unit, and a control unit. The first reception unit receives a first signal including first information related to the reception of a second signal. The second reception unit receives the second signal on the basis of the first information. The control unit controls the first reception unit so that a third signal can be received via the first reception unit in response to the second reception unit receiving the second signal.

Description

Terminal device and base station device

The present invention relates to terminal devices and base station devices used in wireless communication systems.

In today's networks, traffic from mobile devices (smartphones, feature phones, etc.) accounts for the majority of network resources. Furthermore, traffic used by mobile devices is expected to continue to expand in the future.

In addition, IoT (Internet of Things) services (e.g., transportation systems, smart meters, and monitoring systems for devices) are being deployed in a variety of fields. This calls for networks to support services with diverse requirements. To support these diverse services, standards have been developed for fifth-generation mobile communications (5G or NR (New Radio)) (e.g., Non-Patent Documents 1-14), which envision support for a wide range of use cases categorized as eMBB (Enhanced Mobile Broadband), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communication). Furthermore, fifth-generation mobile communications standards also specify technologies for reducing the power consumption of terminal devices.

Paging Early Indicator (PEI) has been introduced as one of the technologies for reducing the power consumption of terminal devices (UE power saving). PEI is a technology that allows a network device (e.g., a base station) to notify a terminal device of the presence or absence of paging before the terminal device receives a paging signal (Non-Patent Documents 6 and 7).

Furthermore, 3GPP (3rd Generation Partnership Project (registered trademark)) is considering low-power wake-up signal and receiver as a new technology to reduce power consumption in terminal devices (Non-Patent Document 15). To implement low-power wake-up signal and receiver, the terminal device is equipped with a receiver with low power consumption (low-power receiver) and a receiver for data communication (main radio unit). Here, when the terminal device is not performing data communication (for example, when in an idle state), it operates the low-power receiver and controls the main radio unit not to operate. Then, when the terminal device receives a wake-up signal via the low-power receiver, it starts up the main radio unit.

3GPP TS 37.324 V17.0.0 3GPP TS 37.340 V17.7.0 3GPP TS 38.201 V17.0.0 3GPP TS 38.202 V17.5.0 3GPP TS 38.211 V17.6.0 3GPP TS 38.212 V17.7.0 3GPP TS 38.213 V17.8.0 3GPP TS 38.214 V17.8.0 3GPP TS 38.215 V17.4.0 3GPP TS 38.300 V17.7.0 3GPP TS 38.321 V17.7.0 3GPP TS 38.322 V17.3.0 3GPP TS 38.323 V17.5.0 3GPP TS 38.331 V17.7.0 3GPP TR 38.869 V18.0.0

When the main radio section of the above-mentioned terminal device is stopped, the signal detection performance of the low-power receiver may deteriorate. For example, signal detection performance may deteriorate in situations where the SINR (Signal-to-Interference-plus-Noise Ratio) is low. Here, for example, when receiving a PDCCH (Physical Downlink Control Channel), it is possible to improve signal detection performance by controlling the aggregation level of control channel elements (CCEs). However, since low-power receivers do not necessarily receive PDCCHs, this method cannot be utilized. For this reason, a method is needed to improve the signal detection performance of low-power receivers.

Therefore, the objective of the disclosed technology is to improve the signal detection performance of terminal devices in wireless communication systems.

A terminal device according to one aspect of the present invention has a first receiving unit that receives a first signal including first information related to the reception of a second signal, a control unit that controls the first receiving unit, and a second receiving unit that receives the second signal based on the first information. The control unit controls the first receiving unit so that a third signal can be received via the first receiving unit in response to the second receiving unit receiving the second signal.

The above-described aspects make it possible to improve the signal detection performance of terminal devices in wireless communication systems.

1 is a diagram illustrating an example of a wireless communication system according to an embodiment. A diagram showing an example of a method by which a terminal device detects paging from a base station. FIG. 2 is a diagram illustrating an example of the configuration of a terminal device. FIG. 1 illustrates an example of a wake-up receiver. FIG. 10 illustrates an example of a method for controlling frequency resources allocated to a wake-up signal. FIG. 10 is a diagram illustrating an example of band allocation for a wake-up signal. FIG. 10 is a diagram illustrating variations of frequency information. FIG. 10 is a diagram illustrating another example of a method for notifying frequency information. FIG. 1 illustrates an example of a method for controlling time resources allocated to wake-up signals. FIG. 10 is a diagram illustrating an example of repeated transmission of a wake-up signal. 10 is a flowchart illustrating an example of a process for detecting a wake-up signal based on time information. FIG. 10 is a diagram illustrating an example of a sequence for notifying the transmission power of a wake-up signal. FIG. 10 is a diagram showing an example of a sequence for notifying the transmission power of a synchronization signal LP-SS.

The following describes the embodiments in detail with reference to the drawings. The problems and examples described in this specification are merely examples and do not limit the scope of the rights of this application. In particular, even if the expressions used are different, as long as they are technically equivalent, the technology of this application can be applied even if the expressions are different, and do not limit the scope of the rights. Furthermore, each embodiment can be combined as appropriate as long as the processing content is not contradictory.

Furthermore, the terms used and technical content described in this specification may be those described in specifications and contributions as communication standards, such as 3GPP, as appropriate. Examples of such specifications include Non-Patent Documents 1 to 15.

Below, examples of the base station device, terminal device, wireless communication system, and communication method disclosed in this application are described in detail with reference to the drawings. Note that the following examples do not limit the disclosed technology.

FIG. 1 shows an example of a wireless communication system according to an embodiment. The wireless communication system according to the embodiment includes a base station 1 and terminal devices 2 (2a to 2d). In this example, the base station 1 is a gNB (next generation Node B) or NR (New Radio) base station, although this is not particularly limited thereto. The terminal device 2 is, for example, a UE (User Equipment).

The base station 1 forms a cell. The base station 1 then accommodates the terminal devices 2 located within the cell. In other words, the base station 1 transmits radio signals to each terminal device 2 and receives radio signals from each terminal device 2. Each terminal device 2 transmits radio signals to the base station 1 and receives radio signals from the base station 1.

FIG. 2 shows an example of a method by which terminal device 2 detects paging from base station 1. In this example, terminal device 2a detects paging from base station 1.

Paging is transmitted at a timing specified by the base station 1. In the case shown in Figure 2A, paging occasions (PO) P1 to P5 are set. The timing of each paging occasion is represented by an SSB (Synchronization Signal Block). The base station 1 then notifies each terminal device 2 of the paging occasion. Each terminal device 2 also acquires the SSB within the SS burst to recognize the paging occasion. Therefore, terminal device 2a can acquire the paging addressed to it by detecting the received signal at each paging occasion.

However, in the case shown in Figure 2A, it takes a long time to establish synchronization with the base station 1. Furthermore, the terminal device 2a needs to monitor all paging opportunities. For example, even if a paging signal is transmitted to the terminal device 2a using paging opportunity P5, the terminal device 2a needs to monitor not only paging opportunity P5 but also paging opportunities P1 to P4. This shortens the sleep time, resulting in insufficient reduction in power consumption.

To address this issue, 3GPP Release 17 proposes the PEI (Paging Early Indicator) shown in Figure 2B as one power-saving method. The PEI notifies the destination terminal in advance of the transmission of a paging signal. For example, when paging is set to be received by terminal device 2a, base station 1 uses the PEI to notify terminal device 2a of a message indicating the paging occasion at which terminal device 2a should receive the paging signal. In this case, terminal device 2a monitors the PEI. Terminal device 2a then receives the paging signal at the paging occasion specified by the PEI (P5 in Figure 2B). With this method, there is no need to monitor all paging occasions, so the sleep time is longer than with the method shown in Figure 2A, and power consumption by terminal device 2 is reduced. However, in use cases where paging is received infrequently, power consumption for monitoring the PEI becomes dominant.

FIG. 3 shows an example of the configuration of a terminal device. The terminal device 2 includes a main radio unit 21, a wake-up receiver 22, and a control unit 23. Note that the terminal device 2 may also include other circuits, devices, or functions not shown in FIG. 3.

The main radio unit (MR: Main Radio) 21 receives radio signals from the base station 1 and transmits radio signals to the base station 1. However, when the terminal device 2 is not performing data communication, the main radio unit 21 is controlled to a sleep mode. Note that "data communication" is not limited to communication of user data, but also includes communication of control signals related to data communication. The main radio unit 21 may be a functional block for receiving data signals. The main radio unit 21 may also be equipped with a digital signal processor for processing received signals.

The wake-up receiver (WUR) 22 receives a wake-up signal (LP-WUS: Low Power Wake-Up Signal) transmitted from the base station 1. Here, when the base station 1 communicates with the terminal device 2, it transmits a wake-up signal to the terminal device 2. When the wake-up receiver 22 detects the wake-up signal, the main radio unit 21 is activated. Thereafter, the terminal device 2 receives the radio signal transmitted from the base station 1 using the main radio unit 21. As an example, the terminal device 2 receives a paging signal transmitted from the base station 1 using the main radio unit 21. In this case, the main radio unit 21 receives the paging signal using the method shown in Figure 2A or 2B.

The wake-up receiver 22 receives a synchronization signal (LP-SS: Low Power Synchronization Signal) to establish synchronization of the wake-up signal with the base station 1. The synchronization signal LP-SS is a notification signal transmitted from the base station 1 at a predetermined interval, and is also used to measure the RRM (Radio Resource Management) of the serving cell.

The wake-up signal (and synchronization signal LP-SS) is transmitted using, for example, OOK (On-Off Keying), although this is not a particular limitation. In this case, the wake-up receiver 22 can detect the wake-up signal using time-domain detection. Therefore, the configuration of the wake-up receiver 22 is simple, and its power consumption is very low compared to the main radio unit 21. The main radio unit 21 and wake-up receiver 22 may share an antenna.

Figure 4 shows an example of a wake-up receiver 22. In this embodiment, the wake-up receiver 22 receives an OOK signal. The wake-up receiver 22 includes a matching circuit 31, a band-pass filter (BPF) 32, an amplifier 33, a detector 34, an amplifier 35, a low-pass filter (LPF) 36, an analog-to-digital converter (ADC) 37, and a signal processing unit 38.

The matching circuit 31 adjusts the impedance between the antenna and the receiving circuit. The bandpass filter 32 extracts frequency components in the RF (Radio Frequency) region where signals (such as wake-up signals and LP-SS synchronization signals) are located. The amplifier 33 is an RF low-noise amplifier that amplifies the output signal of the bandpass filter 32. The detector 34 is, for example, an envelope detector that detects the envelope (i.e., the amplitude-modulated signal) from the received signal.

Amplifier 35 is a baseband amplifier that amplifies the output signal of detector 34. Low-pass filter 36 removes high-frequency components. Analog-to-digital converter 37 converts the output signal of low-pass filter 36 into digital data. In other words, digital data representing the received signal is generated. Then, signal processing unit 38 processes the digital data representing the received signal. In other words, signal processing unit 38 processes the received signal.

The control unit 23 controls the main radio unit 21 and the wake-up receiver 22. That is, the control unit 23 can activate the main radio unit 21 in response to the wake-up receiver 22 receiving a wake-up signal. "Activating the main radio unit 21" includes enabling the main radio unit 21 to receive signals transmitted from the base station 1. The control unit 23 can also control the operation or function of the wake-up receiver 22 based on information notified by the base station 1. The control unit 23 is configured to include, for example, a processor and memory. In this case, the processor executes programs stored in the memory to provide the functions of the terminal device 2.

The base station 1 includes a transmitter 11 and a controller 12. The transmitter 11 is capable of transmitting control signals, wake-up signals, and paging signals including resource information (described below) to the terminal device 2 in accordance with instructions from the controller 12. The controller 12 is capable of generating resource information.

In this way, the terminal device 2 activates the main radio unit 21 in response to the wake-up receiver 22 receiving a wake-up signal. That is, the main radio unit 21 is activated (triggered or activated) in response to receiving a wake-up signal. For this reason, if the wake-up receiver 22 cannot detect a wake-up signal even though the base station 1 is transmitting the wake-up signal, the terminal device 2 cannot communicate with the base station 1. For example, in an environment with a low SINR, the performance of detecting the wake-up signal deteriorates. Therefore, it is necessary to improve the performance of the wake-up receiver 22 for receiving the wake-up signal. Specifically, the resources allocated to the wake-up signal are optimized in accordance with the communication environment (e.g., SINR). At this time, resource information related to the resources allocated to the wake-up signal is notified from the base station 1 to the terminal device 2.

The resources controlled or optimized by the disclosed technology are as follows:
(1) Frequency resources (bandwidth)
(2) Time resource (number of times the wake-up signal is transmitted)
(3) Power or power density

In addition, the resources to be controlled or optimized are notified to the terminal device 2 in the following manner.
(1) SIB (System Information Block)
(2) Use of the LP-SS synchronization signal sequence (3) Blind detection by the terminal device 2

<Frequency resource control>
5 shows an example of a method for controlling frequency resources allocated to a wake-up signal. In this embodiment, the bandwidth of the frequency allocated to the wake-up signal is controlled.

The base station 1 uses the SIB to transmit frequency information related to the transmission of the wake-up signal to the terminal device 2. The base station 1 can broadcast the SIB to each terminal device 2 located within the cell of the base station 1. The terminal device 2 then receives a signal including the SIB transmitted from the base station 1 using the main radio unit 21.

The frequency information includes at least one of the following information:
(1) Bandwidth of the wake-up signal (2) Offset value from a predetermined specified frequency (3) Start frequency of the band allocated to the wake-up signal

Figure 6 shows an example of band allocation for a wake-up signal. In this embodiment, it is assumed that the frequency range (frequencies F1 to F2) for transmitting the wake-up signal is predetermined.

In the case shown in Figure 6A, the starting frequency of the WUS band allocated to terminal device 2 is determined in advance. In the example shown in Figure 6A, the starting frequency of the WUS band allocated to terminal device 2 is F1. In this case, the frequency information only needs to be information indicating the bandwidth of the wake-up signal.

In the case shown in Figure 6B, the frequency information includes information indicating the bandwidth of the wake-up signal and offset information. The offset information indicates an offset value from a predetermined specified frequency. In the example shown in Figure 6B, the offset value is set based on the start frequency (i.e., F1) of the frequency domain for transmitting the wake-up signal.

In the case shown in Figure 6C, the frequency information includes information indicating the bandwidth of the wake-up signal and information indicating the start frequency. This start frequency indicates the start frequency of the WUS band assigned to terminal device 2.

The terminal device 2 obtains the above-mentioned frequency information by receiving the SIB from the base station 1. Then, in the terminal device 2, the control unit 23 reconfigures the wake-up receiver 22 based on the frequency information. As an example, the control unit 23 reconfigures the wake-up receiver 22 so as to extract signal components from the WUS band represented by the frequency information. For example, when the wake-up receiver 22 has the configuration shown in FIG. 4, the control unit 23 may control the passband of the band-pass filter 32, the parameters of the circuit constituting the detector 34, and/or the cut-off frequency of the low-pass filter 36 based on the frequency information. Then, the wake-up receiver 22 waits for a wake-up signal transmitted from the base station 1.

When the base station 1 transmits a data signal (for example, a paging signal shown in Figure 2) to the terminal device 2, it also transmits a wake-up signal to the terminal device 2. At this time, the power density of the wake-up signal is assumed to be constant regardless of the bandwidth. When the wake-up receiver 22 detects the wake-up signal, the control unit 23 activates the main radio unit 21. This causes the state of the main radio unit 21 to transition from sleep mode to normal operation mode. In other words, the terminal device 2 uses the main radio unit 21 to monitor paging.

The bandwidth of the wake-up signal is expressed, for example, by the number of subcarriers or the number of resource blocks used to transmit the wake-up signal. Alternatively, the bandwidth may be expressed using a predetermined index.

In this way, the base station 1 can determine the bandwidth of the wake-up signal. For example, in a communication environment with a low SINR, it is preferable to widen the bandwidth of the wake-up signal. In this case, the probability that the wake-up signal will be correctly received by the terminal device 2 increases. As a result, it is possible to avoid a situation in which the main radio unit 21 is not activated during paging. In other words, the terminal device 2 can detect the paging signal with a high probability, even in a communication environment with a low SINR.

Note that the frequency information is not limited to the example shown in FIG. 6. For example, base station 1 may support multiple candidate bandwidths as the bandwidth of the wake-up signal. In this case, base station 1 notifies terminal device 2 of the multiple candidate bandwidths. In the case shown in FIG. 7A, base station 1 supports two candidate bandwidths (BW1 and BW2). In this case, base station 1 notifies terminal device 2 of the two candidate bandwidths (BW1 and BW2) and the offset value using the SIB.

The terminal device 2 recognizes multiple WUS band candidates based on the frequency information received from the base station 1. In the example shown in FIG. 7A, the terminal device 2 recognizes WUS1 and WUS2. The terminal device 2 then performs blind detection on these WUS band candidates.

Frequency information may also represent a larger bandwidth using one bandwidth (BW1) and multiple offset values, as shown in Figure 7B.

Figure 8 shows another example of a method for notifying frequency information. In this embodiment, the base station 1 notifies the terminal device 2 of frequency information using an SIB, similar to the method shown in Figure 5. At this time, the frequency information represents the initial setting of the WUS band. The initial setting of the WUS band may represent the bandwidth of the wake-up signal, as shown in Figure 6A. The initial setting of the WUS band may also represent the bandwidth and offset value of the wake-up signal, as shown in Figure 6B. Alternatively, the initial setting of the WUS band may represent the bandwidth and start frequency of the wake-up signal, as shown in Figure 6C.

Next, as shown in Figure 8A, the base station 1 uses the synchronization signal LP-SS to transmit a bandwidth instruction to the terminal device 2. The synchronization signal LP-SS is broadcast from the base station 1 to each terminal device within the cell at a predetermined interval. In this example, the synchronization signal LP-SS is composed of a predetermined sequence pattern, as shown in Figure 8B. One or more predetermined bits within the sequence pattern are then used as bandwidth bits. In this example, two bandwidth bits are provided.

The meaning of the bandwidth bits is, for example, as follows: In this example, it is assumed that the bandwidth in the initial setting is 2 MHz.
00: 2MHz (maintain initial setting)
01:3MHz
10:4MHz
11:5MHz

Alternatively, the bandwidth bits may represent an offset value relative to an initial setting, as follows:
00: Zero (maintain initial setting)
01:1MHz
10:2MHz
11:3MHz

The terminal device 2 acquires frequency information from the SIB and receives a bandwidth instruction from the synchronization signal LP-SS. In response to this, the control unit 23 in the terminal device 2 reconfigures the wake-up receiver 22 based on the frequency information and bandwidth instruction. Specifically, the control unit 23 reconfigures the wake-up receiver 22 so that it extracts signal components from the WUS band indicated by the frequency information and bandwidth instruction. At this time, if the bandwidth instruction is 01, 10, or 11, the wake-up receiver 22 is reconfigured to receive the wake-up signal over the expanded bandwidth.

The subsequent sequence is substantially the same in Figures 5 and 8. That is, when the wake-up receiver 22 detects a wake-up signal, the main wireless unit 21 is activated. The main wireless unit 21 then receives a paging signal.

As such, according to the sequence shown in Figure 5, the wake-up receiver 22 is configured semi-fixedly based on the frequency information notified by the SIB. In contrast, according to the sequence shown in Figure 8, the bandwidth can be changed using the synchronization signal LP-SS transmitted at a predetermined interval.

Note that the method of notifying bandwidth using the synchronization signal LP-SS is not limited to the method described above. For example, a sequence pattern may be defined for each bandwidth supported by the base station 1. In this case, the terminal device 2 stores pattern data representing each defined sequence pattern. The terminal device 2 can then recognize the bandwidth used by the base station 1 by calculating the correlation between the sequence pattern it receives using the synchronization signal LP-SS and the pattern data it stores.

<Control of time resources>
9 shows an example of a method for controlling time resources allocated to a wake-up signal. In this embodiment, frequency information and time information are transmitted from a base station 1 to a terminal device 2 using an SIB. The frequency information is as described with reference to FIGS. 5 to 7.

Note that in Figure 9, frequency information and time information are transmitted separately, but frequency information and time information may also be transmitted simultaneously. Also, when the frequency resources allocated to the wake-up signal are fixedly determined, the base station 1 does not need to transmit frequency information to the terminal device 2.

The time information includes at least one of the following information:
(1) Number of times to transmit the wake-up signal (number of repetitions)
(2) Wake-up signal transmission timing

For example, suppose base station 1 transmits four wake-up signals (WUS1 to WUS4) to terminal device 2 as shown in Figure 10. Here, it is assumed that the timing for transmitting the first wake-up signal WUS1 relative to the synchronization signal LP-SS is predetermined. It is also assumed that the period for transmitting multiple wake-up signals (WUS1 to WUS4) is predetermined. In this case, the time information simply specifies the number of times the wake-up signal is transmitted (i.e., the number of repetitions). In the example shown in Figure 10, the number of repetitions is specified as "4."

Alternatively, the time information may represent the timing at which each wake-up signal is transmitted. In this case, in the example shown in Figure 10, the time information represents "T1", "T2", "T3", and "T4". In this case, it may also represent how many symbols after the synchronization signal LP-SS that each wake-up signal is transmitted. In this case, it is preferable to determine the transmission timing of the wake-up signal so as to avoid collision with other signals with higher priority.

The terminal device 2 receives this time information from the base station 1. The control unit 23 then controls the operation of the wake-up receiver 22 in accordance with the received time information. That is, the wake-up receiver 22 receives a wake-up signal according to the number of repetitions indicated by the time information. For example, if the number of repetitions is "4", the wake-up receiver 22 detects the received signal at the four specified reception timings (times T1, T2, T3, and T4 in Figure 10).

The base station 1 repeatedly transmits a wake-up signal according to the time information transmitted to the terminal device 2. The terminal device 2 also detects the received signal at each specified reception timing.

The control unit 23 determines whether a wake-up signal has been transmitted from the base station 1 based on multiple detection results. For simplicity's sake, the control unit 23 determines that a wake-up signal has been transmitted from the base station 1 (or that a wake-up signal has been received) when the received power at a specified reception timing is higher than a threshold level. In this case, the wake-up receiver 22 outputs a received power value at each specified reception timing. The control unit 23 then determines whether a wake-up signal has been transmitted from the base station 1 based on multiple output power values output from the wake-up receiver 22.

For example, when the average of multiple detection results (here, received power values) exceeds a predetermined threshold level, the control unit 23 determines that a wake-up signal has been transmitted from the base station 1. Alternatively, the control unit 23 may determine that a wake-up signal has been transmitted from the base station 1 when the value of at least one of the multiple detection results exceeds a predetermined threshold level.

When it is determined that a wake-up signal has been transmitted from base station 1, the control unit 23 activates the main radio unit 21. The subsequent operation is as described with reference to Figure 5. That is, the main radio unit 21 monitors the paging signal transmitted from base station 1.

FIG. 11 is a flowchart showing an example of a process for detecting a wake-up signal based on time information. The time information includes information indicating the number of times the wake-up signal is transmitted (number of repetitions).

In S1, the terminal device 2 receives frequency information from the base station 1 using the main radio unit 21. The control unit 23 may reconfigure the wake-up receiver 22 based on the frequency information.

In S2, the terminal device 2 receives time information from the base station 1 using the main radio unit 21. In this embodiment, the time information includes information indicating "number of repetitions = N." The control unit 23 then sets the reception timing for receiving a wake-up signal based on this time information. For example, in the embodiment shown in Figure 10, "N = 4," and reception timings T1, T2, T3, and T4 are set. In S3, the control unit 23 initializes the variable i to "1." The variable i represents each reception timing (or the number of times the wake-up signal reception process is executed).

In steps S4 and S5, the terminal device 2 detects the received signal at reception timing i using the wake-up receiver 22. At this time, the wake-up receiver 22 outputs the received power value Pi at reception timing i. The control unit 23 acquires and stores the received power value Pi.

In S6, the control unit 23 determines whether the variable i has reached N. If the variable i is smaller than N, the control unit 23 increments the variable i in S7. After this, the processing of the terminal device 2 returns to S4. That is, the terminal device 2 repeatedly executes the processing of S4 to S5 until the variable i reaches N. As a result, the control unit 23 acquires N received power values.

In S8, the control unit 23 calculates the average value of the N received power values. In other words, the average received power is calculated. In S9, the control unit 23 compares the average received power with a predetermined threshold. This threshold is a power value used to determine whether the base station 1 has transmitted a wake-up signal, and is determined in advance, for example, through measurement or simulation. Note that in S8 and S9, instead of the average value, the maximum value of the N received power values may be used to determine whether the base station 1 has transmitted a wake-up signal.

If the average received power or maximum received power is greater than the threshold, the control unit 23 determines that the base station 1 has transmitted a wake-up signal. In this case, in S10, the control unit 23 activates the main radio unit 21.

In this way, in the sequences shown in Figures 9 to 11, the terminal device 2 monitors the wake-up signal at multiple reception opportunities. Therefore, for example, even if the radio wave environment is unstable and the received power of the wake-up signal transmitted from the base station 1 temporarily drops, the terminal device 2 can reliably detect the wake-up signal. In other words, the wake-up signal detection performance is improved.

Note that if the base station 1 supports multiple candidates for the number of repetitions as time information, it may notify the terminal device 2 of these multiple candidates. In this case, the terminal device 2 may perform detection for the maximum number of repetitions among the multiple candidates. For example, if the candidates for the number of repetitions are 1, 2, and 4, the terminal device 2 sets four reception timings and detects the received signal at each reception timing.

<Power control>
The base station 1 may control the power density of the wake-up signal according to the radio wave environment. In this case, the base station 1 notifies the terminal device 2 of power information indicating the transmission power of the wake-up signal by using the SIB, as shown in Fig. 12. The base station 1 may also maintain a constant bandwidth of the wake-up signal.

Note that in FIG. 12, frequency information and power information are transmitted separately, but they may also be transmitted simultaneously. Furthermore, when the frequency resources allocated to the wake-up signal are fixedly determined, the base station 1 does not need to transmit frequency information to the terminal device 2. Alternatively, the base station 1 may notify the terminal device 2 of the frequency information, time information, and power information.

The power information represents, for example, an offset value relative to the reference power. The reference power is not particularly limited, but may be, for example, the default value for the transmission power of the wake-up signal, the transmission power of the synchronization signal LP-SS, or the power for transmitting SSB. The default offset value is zero. In cases where the radio wave environment is poor, the offset value is determined so that the transmission power of the wake-up signal is increased. However, the power information may also represent the absolute value of the transmission power of the wake-up signal.

The operation of the terminal device 2 is substantially the same in Figures 5 and 12. Therefore, the terminal device 2 does not need to perform any specific processing based on the power information. However, the terminal device 2 may perform some processing based on the power information. For example, if the received power of the wake-up signal slightly exceeds the threshold even though the transmission power of the wake-up signal has been increased, the terminal device 2 can estimate that it is located at the edge of the cell. In this case, the terminal device 2 may estimate that errors are likely to occur in signal reception by the main radio unit 21, and may control the receiving sensitivity of the main radio unit 21.

In the sequence shown in Figure 12, the transmission power of the wake-up signal is controlled to make it easier for the terminal device 2 to receive the wake-up signal. However, in order to receive the wake-up signal, it is necessary to detect the synchronization signal LP-SS first. Therefore, the base station 1 may control the transmission power of the synchronization signal LP-SS depending on the radio wave environment.

Figure 13 shows an example of a sequence for notifying the transmission power of the synchronization signal LP-SS. In this embodiment, the base station 1 controls the transmission power of the synchronization signal LP-SS depending on the radio wave environment. At this time, the base station 1 may also control the transmission power of the wake-up signal in the same way as the synchronization signal LP-SS. Then, as shown in Figure 13, the base station 1 notifies the terminal device 2 of power information related to the power of the synchronization signal LP-SS using the SIB. Note that although the frequency information and power information are transmitted separately in Figure 13, the frequency information and power information may also be transmitted simultaneously.

Power information related to the power of the synchronization signal LP-SS represents, for example, an offset value relative to the reference power. The reference power may be the default value for the power of the synchronization signal LP-SS, or the power for transmitting SSB. In cases where the radio wave environment is poor, the offset value is determined so that the transmission power of the synchronization signal LP-SS (and the wake-up signal) is increased.

The terminal device 2 monitors the received signal using the wake-up receiver 22, referencing the power information notified by the base station 1. For example, assume that the base station 1 notifies the terminal device 2 of power information indicating that the transmission power of the synchronization signal LP-SS has been increased by an offset power ΔP. In this case, when the wake-up receiver 22 receives the synchronization signal LP-SS, the control unit 23 calculates the original reception power of the synchronization signal LP-SS by subtracting ΔP from the detected reception power value. Also, assume that the base station 1 increases the transmission power of the wake-up signal by the offset power ΔP, just like the synchronization signal LP-SS. In this case, when the wake-up receiver 22 receives the wake-up signal, the control unit 23 can calculate the original reception power of the wake-up signal by subtracting ΔP from the detected reception power value.

The subsequent operations are substantially the same in Figures 5 and 13. That is, the control unit 23 of the terminal device 2 determines whether to activate the main wireless unit 21 based on the detection result of the wake-up receiver 22. However, the control unit 23 determines whether to activate the main wireless unit 21 based on the result of correcting the received power value with an offset value.

1 Base Station 2 Terminal Device 21 Main Radio Unit 22 Wake-up Receiver 23 Control Unit

Claims (13)

a first receiving unit that receives a first signal including first information related to reception of a second signal;
a control unit that controls the first receiving unit;
a second receiving unit that receives the second signal based on the first information,
The control unit controls the first receiving unit so that the second receiving unit can receive a third signal via the first receiving unit in response to receiving the second signal. The terminal device according to claim 1 , wherein the first information includes frequency information relating to a band of the second signal. The terminal device according to claim 2 , wherein the control unit reconfigures the second receiving unit based on the frequency information. The terminal device according to claim 2, characterized in that the first information includes at least one of information representing a bandwidth of the second signal, information representing a start frequency of a band allocated to the second signal, or information representing an offset value relative to a predetermined specified frequency. The terminal device according to claim 2 , wherein the first information represents a plurality of candidates for the bandwidth of the second signal. the second receiving unit further receives a fourth signal including second information relating to a bandwidth of the second signal;
The terminal device according to claim 1 , wherein the second receiving unit receives the second signal based on the first information and the second information. The terminal device according to claim 1 , wherein the first information includes time information relating to a transmission timing of the second signal. The terminal device according to claim 7 , wherein the time information includes information indicating the number of repetitions of the second signal. The control unit
setting a plurality of reception timings based on the time information;
The terminal device according to claim 8, wherein the second receiving unit determines whether or not the second signal has been received based on received power detected by the second receiving unit at each of the plurality of reception timings. The terminal device according to claim 1 , wherein the first information includes information relating to a transmission power of the second signal. The terminal device according to claim 1 , wherein the first information includes information relating to a transmission power of a synchronization signal for the second receiving unit to receive the second signal. A base station device connected to a terminal device,
a transmitting unit that transmits a first signal including first information related to reception of a second signal by the terminal device to the terminal device, transmits the second signal to the terminal device after transmitting the first signal, and transmits a third signal to the terminal device after transmitting the second signal;
the first signal and the third signal are received by a first receiving unit in the terminal device;
the second signal is received by a second receiving unit in the terminal device;
In the terminal device, the first receiving unit is controlled to receive the third signal in response to the second signal being received by the second receiving unit. A wireless communication system including a base station device and a terminal device,
The terminal device
a first receiving unit;
a second receiving unit;
a control unit,
the base station device transmits to the terminal device a first signal including first information related to reception of a second signal by the terminal device;
the first receiving unit receives the first signal;
the base station device transmits the second signal to the terminal device;
the second receiving unit receives the second signal based on the first information;
the control unit controls the first receiving unit in response to the second receiving unit receiving the second signal so as to receive a third signal via the first receiving unit;
the base station device transmits the third signal to the terminal device;
The wireless communication system according to claim 1, wherein the first receiving unit receives the third signal.