Terminal device, base station device, and wireless communication system

Abstract

The present invention includes a measurement unit that measures one or more measurement signals, and a control unit that, when the measurement value of at least one of the measurement signals is equal to or greater than an addition value obtained by adding a first threshold value to a first measurement value of a first signal, transmits, to a base station device, a measurement result including information related to the measurement value, and generates the measurement result in a format in which the base station device can recognize which of the measurement signals includes the measurement value equal to or greater than the addition value.

Description

Terminal device, base station device, and wireless communication system

[0001] The present invention relates to a terminal device, a base station device, and a wireless communication system.

[0002] In a wireless communication system, a terminal device measures beams transmitted by a cell to which it is connected in order to determine an appropriate beam for receiving a signal from a base station. Furthermore, in order to switch to another cell as the terminal device moves, the terminal device measures beams transmitted by neighboring cells other than the cell with which it is currently communicating or on which it is camped (sometimes referred to as the current cell) (see Non-Patent Documents 1 to 3). For example, the terminal device periodically measures beams and transmits the measurement results to the base station device of the current cell.

[0003] However, with such beam management, even a terminal device that is not moving must periodically transmit measurement results, which generates a communication load in wireless communication.

[0004] Therefore, in order to reduce this communication load, beam reporting based on trigger events has been studied (Non-Patent Document 4). Although the terminal device measures beams, it transmits the measurement results only when a certain trigger event condition is met. This reduces the number of times the measurement results are transmitted, thereby reducing the communication load. The condition is, for example, that the measurement result of at least one beam out of the measurement results of one or more beams is better than the measurement result of the beam of the current cell (hereinafter sometimes referred to as the current beam) by a threshold or more. The number N of beams to be measured (N is a natural number) and the threshold are notified, for example, by the base station device.

[0005] 3GPP TS 38.133 V18.6.03GPP TS 38.300 V18.2.03GPP TS 38.331 V18.2.0RP-234007

[0006] However, the base station device may not be able to determine which beam among the N measurement results satisfies the condition of a trigger event. If the base station device is unable to determine whether the condition of a trigger event is satisfied, for example, when the communication quality of the currently used beam deteriorates as the terminal device moves, the base station device may not be able to properly determine which beam to switch to. For example, when selecting a cell to which the terminal device should move, the base station device may not be able to properly determine which beam's cell to move to.

[0007] Therefore, one disclosure provides a terminal device, a base station device, and a wireless communication system that can recognize which beam satisfies the conditions for a trigger event from the measurement results of multiple beams.

[0008] The base station device includes a measurement unit that measures one or more measurement signals, and a control unit that, if at least one measurement value of the measurement signals is equal to or greater than a sum obtained by adding a first threshold value to a first measurement value of a first signal, transmits a measurement result including information about the measurement value to a base station device and generates the measurement result in a format that allows the base station device to recognize which of the measurement signals has a measurement value equal to or greater than the sum value.

[0009] One disclosure is capable of recognizing, from the measurement results of multiple beams, which beam satisfies the conditions for a trigger event.

[0010] FIG. 1 is a diagram showing an example of the configuration of a wireless communication system 10. FIG. 2 is a diagram showing an example of the configuration of a base station device 200. FIG. 3 is a diagram showing an example of the configuration of a terminal device 100. FIG. 4 is a diagram showing an example of a beam report due to a trigger event. FIG. 5 is a diagram showing an example of the relationship between a threshold and a measurement value. FIG. 6 is a diagram showing an example of a beam report in Scheme 1. FIG. 7 is a diagram showing an example of a beam report in Scheme 2-1. FIG. 8 is a diagram showing an example of a beam report in Scheme 2-2. FIG. 9 is a diagram showing an example of a beam report in Scheme 3. The beam index is the same as in Scheme 1. FIG. 10 is a diagram showing an example of a beam report in Scheme 4-1. FIG. 11 is a diagram showing an example of a beam report in Scheme 4-2. FIG. 12 is a diagram showing an example of a beam report in Scheme 4-3. FIG. 13 is a diagram showing an example of a beam report in Scheme 4-4. FIG. 14 is a diagram showing an example of a beam report in Scheme 4-5. FIG. 15 is a diagram showing an example of a beam report in Scheme 5. FIG. 16 is a diagram showing an example of a beam report in Scheme 6.

[0011] [First Embodiment] A first embodiment will be described.

[0012] 1 is a diagram showing an example of the configuration of a wireless communication system 10. The wireless communication system 10 includes a base station device 200 and a terminal device 100.

[0013] The base station device 200 is a device that is wirelessly connected to and performs wireless communication with the terminal device 100, and is, for example, an eNodeB or a gNodeB. The base station device 200 forms a communication area A200 in which wireless communication is possible.

[0014] The terminal device 100 is a communication device that is wirelessly connected to the base station device 200 and transmits and receives data, and is, for example, a smartphone or tablet terminal. The current cell of the terminal device 100 is a cell corresponding to the communication area A2. The current beam of the terminal device 100 is, for example, a beam that constitutes the communication area A2. The terminal device 100 responds to beam reports due to trigger events. The terminal device 100 determines a reference signal for quality measurement of the current beam (a beam to be measured as the current beam) in the following manner: - A QCL reference signal (reference signal) corresponding to a TCI state identifier specified by the base station device 200 - An SSB signal having a QCL relationship with the reference signal corresponding to the TCI state identifier specified by the base station device 200 The TCI (Transmission configuration indicator state) state is a transmission setting. For example, the transmission configuration of PDCCH DMRS, PDSCH DMRS (and CSI-RS) conveys the QCL (Quasi Co-Location) relationship (sharing the same radio environment characteristics) with the reference signal (SSB or CSI-RS).

[0015] 2 is a diagram showing an example of the configuration of the base station device 200. The base station device 200 includes a CPU (Central Processing Unit) 210, a storage 220, a memory 230, an antenna 240, and a wireless communication circuit 250.

[0016] The storage 220 is an auxiliary storage device that stores programs and data, such as a flash memory, a hard disk drive (HDD), or a solid state drive (SSD). The storage 220 stores a wireless communication control program 221 and a beam report receiving program 222.

[0017] The memory 230 is an area into which the programs stored in the storage 220 are loaded. The memory 230 may also be used as an area in which the programs store data.

[0018] The wireless communication circuit 250 is a device that performs wireless communication with the terminal device 100 via the antenna 240. The base station device 200 transmits and receives signals (messages) to and from the terminal device 100 via the wireless communication circuit 250.

[0019] The CPU 210 is a processor that loads programs stored in the storage 220 into the memory 230, executes the loaded programs, configures each unit, and realizes each process.

[0020] The CPU 210 executes the wireless communication control program 221 to configure a determination unit and a receiving unit and perform wireless communication control processing. The wireless communication control processing is processing for controlling wireless communication with the terminal device 100. In the wireless communication control processing, the base station device 200 wirelessly connects to the terminal device 100, transmits signals to the terminal device 100, and receives signals from the terminal device 100.

[0021] The CPU 210 executes the beam report receiving program 222 to construct a determination unit and a receiving unit and perform beam report receiving processing. The beam report receiving processing is processing to receive a beam report (beam measurement result) transmitted from the terminal device 100. The base station device 200 receives the beam report and performs, for example, selection of a beam to switch the terminal device 100 to.

[0022] 3 is a diagram illustrating an example of the configuration of the terminal device 100. The terminal device 100 includes a CPU 110, a storage 120, a memory 130, an antenna 140, and a wireless communication circuit 150.

[0023] The storage 120 is an auxiliary storage device such as a flash memory, HDD, or SSD that stores programs and data. The storage 120 stores a wireless communication program 121 and a beam report transmission program 122.

[0024] The memory 130 is an area into which the programs stored in the storage 120 are loaded. The memory 130 may also be used as an area in which the programs store data.

[0025] The wireless communication circuit 150 is a device that performs wireless communication with the base station device 200 via the antenna 140. The terminal device 100 transmits and receives signals (messages) to and from the base station device 200 via the wireless communication circuit 150.

[0026] The CPU 110 executes the wireless communication program 121 to configure a control unit and a transmission unit and perform wireless communication processing. The wireless communication processing is processing for establishing a wireless connection with the base station device 200 and performing wireless communication. In the wireless communication processing, the terminal device 100 performs wireless communication with the base station device 200, receives signals transmitted by the base station device 200, and transmits signals to the base station device 200.

[0027] By executing the beam report transmission program 122, the CPU 110 constructs a control unit and a transmission unit and performs beam report transmission processing. The beam report transmission processing is a process in which beams of adjacent cells are measured, and if a trigger event condition is met, the measurement results of N beams are transmitted to the base station device 200. The trigger event condition is, for example, that the measurement result of at least one beam among the measured beams is better than the measurement result of the current beam by a threshold or more. The number N of beams to be measured and the threshold are notified, for example, by the base station device 200. Furthermore, N and the threshold are shared between the base station device 200 and the terminal device 100, and the base station device 200 is assumed to be aware of N and the threshold.

[0028] <Beam Report for Trigger Event> Fig. 4 is a diagram showing an example of a beam report due to a trigger event. The terminal device 100 monitors the reference signal and, for example, periodically measures the reference signal. In Fig. 4, reference signals R1-1 to R1-3 are measured at a certain timing, reference signals R2-1 to R2-3 are measured at the next timing, and reference signals R3-1 to R3-3 are measured at the next timing. Note that the reference signals R1, R2, and R3 may be the same or different signals. The reference signal is, for example, CSI-RS or SSB.

[0029] Then, when an event occurs (when the trigger event condition is satisfied), the terminal device 100 transmits a beam report. In Fig. 4, the condition is satisfied in the third measurement, and the terminal device 100 transmits a beam report BR1 to the base station device 200. The beam report is, for example, a CSI report.

[0030] 5 is a diagram showing an example of the relationship between thresholds and measurement values. The RSRP (Reference Signal Received Power) of the current beam plus a first threshold is called a trigger value. If the RSRP of the new beam (reference signal) exceeds the trigger value (if it is equal to or greater than the trigger value), the terminal device 100 determines that the condition is met. In addition to RSRP, RSRQ (Reference Signal Received Quality) or SINR (Signal to Interference plus Noise Ratio) may also be used as a measurement value.

[0031] <Beam report notification method> Below, each beam report notification method will be explained. The notification methods differ in the transmission format of the beam report, but the transmission conditions and transmission timing of the beam report are assumed to be the same. In the following example, N=4, and the RSRP is assumed to be the largest at #1, decreasing in order of #2, #3, and #4. The beam measured in the beam report is, for example, a measurement signal (reference signal) transmitted by a currently connected cell in addition to the current beam. In addition, the beam measured in the beam report is, for example, a measurement signal (reference signal) transmitted by an adjacent cell, etc.

[0032] <1. Scheme 1> Fig. 6 is a diagram showing an example of a beam report in scheme 1. Information elements of the beam report include a beam index and a measurement value. The beam index is, for example, a beam identifier. The measurement value is, for example, RSRP.

[0033] The beam index lists, for example, from the top, the identifier of beam 1 (beam #1), the identifier of beam 2 (beam #2), the identifier of beam 3 (beam #3), and the identifier of beam 4 (beam #4).

[0034] The measured values ​​are listed with RSRP#1 of beam 1, which has the largest RSRP, at the top.Then, from top to bottom, the differences from RSRP#1, namely RSRP#2-RSRP#1, RSRP#3-RSRP#1, and RSRP#4-RSRP#1, are listed.

[0035] It should be noted that the measured values ​​may be listed as they are, rather than as differences.

[0036] Because the beam report has been transmitted, the base station device 200 can recognize that at least the top-listed beam 1 has exceeded the trigger value. However, even if the base station device 200 receives a beam report using method 1, the measurement value of the current beam is unknown, so it cannot recognize the trigger value and cannot recognize whether beams other than beam 1 satisfy the conditions for a trigger event.

[0037] <2. Method 2> Method 2 is a method in which a value using a trigger value is included in a beam report. Two patterns of Method 2, Method 2-1 and Method 2-2, will be described.

[0038] 7 is a diagram showing an example of a beam report in method 2-1. The beam index is the same as in method 1.

[0039] The measurement values ​​are listed in the same order as the beam indexes. The measurement values ​​are listed at the top, with the difference between RSRP#1 and the trigger value (RSRP#1-trigger value) for beam 1, which has the highest RSRP. Then, from top to bottom, the difference between RSRP#2 and the trigger value (RSRP#2-trigger value), the difference between RSRP#3 and the trigger value (RSRP#3-trigger value), and the difference between RSRP#4 and the trigger value (RSRP#4-trigger value) are listed.

[0040] If the measurement value is a positive number (or equal to or greater than 0), the base station device 200 can determine that the beam satisfies the condition for a trigger event.

[0041] 8 is a diagram showing an example of a beam report in method 2-2. The beam index is the same as in method 1.

[0042] The measurement values ​​are listed in the same order as the beam indexes. The difference between RSRP#1 of beam 1, which has the largest RSRP, and the trigger value (RSRP#1-trigger value) is listed at the top. Then, from top to bottom, the differences from RSRP#1, namely RSRP#2-RSRP#1, RSRP#3-RSRP#1, and RSRP#4-RSRP#1, are listed.

[0043] The base station device 200 can determine whether or not each of RSRP#2 to RSRP#4 satisfies the trigger event condition based on the difference with RSRP#1 and the difference between RSRP#1 and the trigger value. For example, if the value of RSRP#1 - RSRP#2 is smaller than RSRP#1 - the trigger value, the base station device 200 determines that beam 2 satisfies the trigger event condition.

[0044] <Method 3> Method 3 is a method in which the measurement value of a beam that does not satisfy the trigger event condition is displayed as a specific value.

[0045] 9 is a diagram showing an example of a beam report in Method 3. The beam index is the same as in Method 1.

[0046] The measurement values ​​are listed in the same order as the beam indexes. The measurement values ​​are listed with RSRP#1 of beam 1, which has the largest RSRP, at the top. Then, from top to bottom, the differences from RSRP#1, RSRP#2-RSRP#1, RSRP#3-RSRP#1, are listed.

[0047] However, for RSRP#4, the trigger event condition is not met (it is less than the trigger value), so a specific value is listed. The specific value indicates that the trigger event condition is not met.

[0048] The base station device 200 can determine that the beam containing the specific value does not satisfy the trigger event condition.

[0049] <Method 4> Method 4 is a method in which the measurement value of the current beam is included in the beam report. Five patterns of Method 4, Methods 4-1 to 4-5, will be described.

[0050] 10 is a diagram showing an example of a beam report in method 4-1. The beam index is the same as in method 1.

[0051] The RSRP of the current beam (RSRP#Current) is listed at the top of the measurement values. The following measurement values ​​are listed from the second to fifth positions, with RSRP#1 to #4 listed in the same order as the beam index. Note that the current beam is not included in the beam index.

[0052] 11 is a diagram showing an example of a beam report in method 4-2. The beam index is the same as in method 1.

[0053] The RSRP of the current beam (RSRP#Current) is listed at the top of the measurement values. The following measurement values, from second to fifth, are listed in the same order as the beam indexes, with the difference from RSRP#1.

[0054] 12 is a diagram showing an example of a beam report in method 4-3. The beam index is the same as in method 1.

[0055] The RSRP of the current beam (RSRP #Current) is listed at the top of the measurement values. The following measurement values, from second to fifth, are listed in the same order as the beam index, with the difference from the RSRP of the current beam.

[0056] Figure 13 is a diagram showing an example of a beam report in method 4-4. The beam indexes are listed in descending order of measured value, including the current beam. If the RSRP of the current beam is smaller than that of the other four measured beams, the current beam will not be included in the beam index. In the example of Figure 13, the identifier of the current beam (Beam #Current) is located between Beam 2 and Beam 3.

[0057] The measurement values ​​are listed in the same order as the beam indexes. The measurement values ​​are listed at the top, with RSRP#1 for beam 1, which has the largest RSRP, listed first. Then, from top to bottom, RSRs, RSRP#2, RSRP#Current, and RSRP#3 are listed.

[0058] 14 is a diagram showing an example of a beam report in Method 4-5. The beam index is the same as in Method 4-4.

[0059] The measured values ​​are listed in the same order as the beam indexes. The RSRP #1 of beam 1, which has the largest RSRP, is listed at the top. Then, the differences from RSRP #1 are listed from top to bottom.

[0060] Since the base station device 200 can recognize the RSRP of the current beam, it can calculate the trigger value using the first threshold value and determine which beam satisfies the trigger event condition.

[0061] <Method 5> Method 5 is a method in which only the measurement values ​​of beams that satisfy the trigger event conditions are displayed.

[0062] FIG. 15 is a diagram showing an example of a beam report in Method 5. Only beams that satisfy the trigger event conditions are listed as beam indexes. In the case of FIG. 15, beam 4 does not satisfy the trigger event conditions, so it is not listed. And beam 3 is listed twice as a beam index.

[0063] The measurement values ​​are published in the same order as the beam indexes. The measurement values ​​are published with RSRP#1 of beam 1, which has the largest RSRP, at the top. Then, from top to bottom, RSRP#2, RSRP#3, and RSRP#3 are published. In other words, RSRP#3 is published twice.

[0064] The base station device 200 can recognize that beams 1 to 3 satisfy the trigger event condition by skipping the overlapping beam (beam 3 in the case of FIG. 15).

[0065] <Method 6> Method 6 is a method in which information indicating beams that satisfy the trigger event condition is included in a beam report.

[0066] 16 is a diagram showing an example of a beam report in Method 6. The beam report contains two bits of information indicating beams that are equal to or greater than the trigger value (satisfy the trigger event condition). For example, the two bits of information indicate that 00 indicates only beam 1, 01 indicates beams 1 and 2, 10 indicates beams 1 to 3, and 11 indicates all beams 1 to 4 satisfy the trigger event condition.

[0067] The beam index is the same as in Method 1.

[0068] The measured values ​​are listed in the same order as the beam indexes. The measured values ​​are listed with RSRP#1 of beam 1, which has the largest RSRP, at the top. Then, RSRP#2, RSRP#3, and RSRP#4 are listed in order from top to bottom.

[0069] The base station device 200 can recognize a beam that satisfies the trigger event condition from the two-bit information.

[0070] [Other Embodiments] In each of the above methods, the actual measured value of RSRP may be replaced with a differential value. Also, the differential value may be replaced with the actual measured value of RSRP. Also, the trigger value may be replaced with the RSRP of the current beam. Also, the RSRP of the current beam may be replaced with the trigger value.

[0071] 10: Wireless communication system 100: Terminal device 110: CPU 120: Storage 121: Wireless communication program 122: Beam report transmission program 130: Memory 140: Antenna 150: Wireless communication circuit 200: Base station device 210: CPU 220: Storage 221: Wireless communication control program 222: Beam report reception program 230: Memory 240: Antenna 250: Wireless communication circuit

Claims

1. A terminal device having: a measurement unit that measures one or more measurement signals; and a control unit that, when at least one measurement value of the measurement signals is equal to or greater than a sum obtained by adding a first threshold value to a first measurement value of a first signal, transmits a measurement result including information about the measurement value to a base station device; and generates the measurement result in a format that allows the base station device to recognize which of the measurement signals has a measurement value equal to or greater than the sum.

2. The terminal device according to claim 1, wherein the control unit includes in the measurement result a numerical value obtained by subtracting the added value from the measurement value.

3. The terminal device according to claim 1, wherein the control unit includes in the measurement result a fixed value indicating that the measurement value is smaller than the added value, in place of the measurement value.

4. The terminal device according to claim 1, wherein the first threshold is a numerical value recognized by the base station device, and the control unit includes information relating to the first measurement value in the measurement result.

5. The terminal device according to claim 1, wherein the control unit does not include the measurement value smaller than the added value in the measurement result.

6. The terminal device according to claim 1, wherein the control unit includes in the measurement result information indicating which of the measurement values ​​included in the measurement result is equal to or greater than the additional value.

7. A terminal device as described in claim 1, wherein the first signal is a signal corresponding to a beam transmitted by a first cell to which the terminal device is connected, and the measurement signal is a signal corresponding to a beam transmitted by the first cell other than the beam received by the terminal device.

8. A base station device having: a receiving unit that measures measurement signals and receives measurement results including information about the measurement values ​​that are transmitted when at least one measurement value of the measurement signals is equal to or greater than a sum obtained by adding a first threshold value to a first measurement value of a first signal; and a determining unit that determines which of the measurement signals is equal to or greater than the sum based on the measurement results.

9. A wireless communication system having a terminal device that measures one or more measurement signals, and when at least one measurement value of the measurement signals is equal to or greater than a sum obtained by adding a first measurement value of a first signal to a first threshold, generates measurement results including information about the measurement values ​​in a format that allows a base station device to recognize which of the measurement signals has a measurement value equal to or greater than the sum, and transmits the measurement results to the base station device; and the base station device that receives the measurement results and determines which of the measurement signals has a measurement value equal to or greater than the sum based on the measurement results.

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