Terminal, Communication Method, and Integrated Circuit

Abstract

The present invention achieves an improvement in channel estimation accuracy using a reference signal. This terminal comprises: a control circuit for setting a first upper limit value of a frequency interval at which a first reference signal is placed in a first bandwidth such that the first upper limit value is smaller than a second upper limit value of a frequency interval at which a second reference signal is placed in a second bandwidth wider than the first bandwidth; and a transmission circuit for transmitting the first reference signal on the basis of the first upper limit value.

Description

Technical Field

[0001] The present disclosure relates to a terminal, a base station, and a communication method.

Background Art

[0002] In Release 17 of the 3rd Generation Partnership Project (3GPP) (hereinafter referred to as "Rel. 17"), for the functional enhancement of Multiple-Input Multiple Output (MIMO) applied to New Radio access technology (NR), the improvement of the coverage performance or capacity performance of the Sounding Reference Signal (SRS) has been discussed (see, for example, Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

[0004] However, there is room for study on a method for improving the channel estimation accuracy using a reference signal.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a terminal, a base station, and a communication method for improving the channel estimation accuracy using a reference signal.

[0006] A terminal according to an embodiment of the present disclosure includes a control circuit configured to set a first upper limit value of a frequency interval at which a first reference signal is arranged in a first bandwidth to be smaller than a second upper limit value of a frequency interval at which a second reference signal is arranged in a second bandwidth wider than the first bandwidth, and a transmission circuit configured to transmit the first reference signal based on the first upper limit value.

[0007] These general or specific aspects may be implemented in a system, apparatus, method, integrated circuit, computer program, or recording medium, or may be implemented in any combination of a system, apparatus, method, integrated circuit, computer program, and recording medium.

[0008] According to an embodiment of the present disclosure, the channel estimation accuracy using a reference signal can be improved.

[0009] Further advantages and effects in an embodiment of the present disclosure will be clarified from the specification and drawings. Such advantages and / or effects are provided by some embodiments and the features described in the specification and drawings respectively, but it is not necessary to provide all of them in order to obtain one or more identical features.

Brief Description of the Drawings

[0010]

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MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] Regarding the SRS used in NR (for example, referred to as "NR SRS"), for example, a base station (which may also be referred to as an "eNB" or a "gNB") may notify (or configure) a terminal (which may also be referred to as a "User Equipment (UE)") with information regarding the configuration of the SRS (hereinafter referred to as "SRS configuration information"). The SRS configuration information may define, for example, a "SRS resource set", which is a group of parameters used for each SRS resource, such as the transmission timing of the SRS, the transmission frequency band of the SRS, the sequence number for reference signal generation, the number of transmission Combs (or the transmission subcarrier interval), and the cyclic shift amount. The SRS configuration information may be configured by upper layer signaling such as the Radio Resource Control (RRC) layer. Also, the SRS configuration information may be referred to as "SRS-Config" configured in the RRC layer, for example.

[0013] As an example of the transmission method in the frequency band of NR SRS, a "wideband SRS transmission method" and a "narrowband SRS transmission method" can be mentioned. The wideband may correspond to, for example, a frequency band capable of transmitting the SRS (referred to as, for example, a "sounding bandwidth" or a "frequency band capable of channel estimation"). Also, the narrowband may be, for example, a band narrower than the sounding bandwidth (or the wideband). In the wideband SRS transmission method, for example, the SRS may be transmitted in the transmission bandwidth corresponding to the Bandwidth part (BWP), and wideband channel estimation may be performed at once. Also, in the narrowband SRS transmission method, for example, while changing the transmission band over time (in other words, frequency hopping), the SRS may be transmitted in a narrowband, and wideband channel estimation may be performed using a plurality of narrowband SRSs.

[0014] For example, in a terminal located near the cell boundary, the path loss can be larger compared to a terminal located near the cell center. Also, there is an upper limit to the maximum transmission power of the terminal. Therefore, for example, when a terminal near the cell boundary transmits SRS in a wideband, the received power per unit frequency at the base station tends to be low. For this reason, when a terminal near the cell boundary transmits SRS in a wideband, for example, the reception quality (e.g., Signal to Interference and Noise Ratio (SINR)) becomes low, and the channel estimation accuracy may deteriorate. Therefore, for a terminal near the cell boundary, for example, a narrowband SRS transmission method in which the allocation of transmission power is restricted to a frequency band narrower than the wideband (in other words, the transmission power density is increased) may be applied.

[0015] On the other hand, for example, in a terminal near the cell center, the path loss can be smaller compared to a terminal near the cell boundary. Therefore, even if a terminal near the cell center transmits SRS in a wideband, since it is possible to ensure the received power per unit frequency for channel estimation at the base station, a wideband SRS transmission method may be applied.

[0016] Also, for example, in NR SRS, regardless of whether it is wideband SRS or narrowband SRS, the sounding band may be set the same among terminals. In this case, for example, the transmission bandwidth of the wideband SRS may be set to N times (N is an integer) the transmission bandwidth of the narrowband SRS. For example, when a terminal transmits narrowband SRS, by applying frequency hopping N times, it becomes possible to estimate the channel quality in the same frequency band as the wideband SRS.

[0017] For example, in NR SRS, the minimum transmission bandwidth of SRS may be 4 resource blocks (RB), and the transmission bandwidth of SRS (e.g., the number of RBs) may be a multiple of 4 (see, for example, Non-Patent Document 2).

[0018] FIG. 1 is a diagram showing an example of transmission of narrowband SRS in NR SRS.

[0019] In FIG. 1, the sounding bandwidth is, for example, 16 RBs. For example, in FIG. 1, the terminal may perform frequency hopping four times for an SRS with a transmission bandwidth of 4 RBs (for example, a narrowband SRS).

[0020] In 3GPP Rel. 17, for example, in narrowband SRS transmission, a method of setting a high transmission power density of the SRS may be assumed. By increasing the transmission power density of the SRS, for example, the channel estimation accuracy of terminals with high path loss, such as terminals existing near the cell boundary, can be improved, and the coverage performance of the SRS can be improved.

[0021] Examples of methods for increasing the transmission power density of the SRS include, for example, a method of narrowing the transmission bandwidth of the SRS, or a method of increasing the number of transmission Combs (in other words, a method of widening the transmission subcarrier interval). Also, for example, frequency hopping is applied to narrowband SRS transmission, and channel estimation over a wideband is assumed.

[0022] However, the narrower the transmission bandwidth of the SRS, or the greater the number of transmission Combs, the smaller the sequence length of the sequence for SRS generation may become. For example, the smaller the sequence length of the sequence for SRS generation, the greater the cross-correlation (or interference) between SRSs using different sequences, and the channel estimation accuracy may deteriorate.

[0023] Also, the smaller the sequence length of the sequence for SRS generation, the smaller the number of sequences having good Peak to Average Power Ratio (PAPR) characteristics or cross-correlation characteristics (for example, Constant Amplitude Zero Auto Correlation (CAZAC) characteristics) may be. For example, in NR, 30 sequences can be used for each transmission bandwidth as the sequence for SRS generation, and in adjacent cells, interference between adjacent cells can be reduced by transmitting SRSs generated from different sequences. For example, the smaller the sequence length of the sequence for SRS generation, the greater the cross-correlation (or interference), and the channel estimation accuracy may deteriorate.

[0024] For example, the sequence length "M" of the SRS generation sequence sc,b SRS may be calculated based on Equation (1) (see, for example, Non-Patent Document 2). [Number]

[0025] In Equation (1), m SRS,b represents the transmission bandwidth [RB] of the SRS, and N sc RB represents the number of subcarriers [sc / RB] per RB, and K TC represents the number of transmission Combs (Comb interval) [sc].

[0026] In NR, for example, N sc RB = 12 (fixed value) may be used. In this case, for example, the SRS transmission bandwidth (m SRS,b ), the number of transmission Combs (K TC ), and the sequence length (M sc,b SRS ) have the relationship shown in FIG. 2. For example, as shown in FIG. 2, when the SRS transmission bandwidth is 2 RB or less, depending on the number of transmission Combs, the sequence length may be less than a certain threshold (for example, 3 [sc]). For example, when the sequence length is less than a certain threshold (for example, 3 [sc]), the cross-correlation (interference) between SRSs increases, and the channel estimation accuracy by SRS may deteriorate.

[0027] Therefore, in one embodiment of the present disclosure, a method for improving the channel estimation accuracy using SRS will be described.

[0028] (Embodiment 1) [Overview of Communication System] A communication system according to one aspect of the present disclosure may include, for example, a base station 100 (for example, a gNB or an eNB) and a terminal 200 (for example, a UE).

[0029] For example, the base station 100 may be a base station for NR, and the terminal 200 may be a terminal for NR. The base station 100 may, for example, set SRS configuration information regarding SRS transmission for the terminal 200 and receive SRS from the terminal 200. Further, the terminal 200 may transmit SRS with a certain bandwidth and transmission Comb number in a specified (or set) transmission band based on the SRS configuration information from the base station 100.

[0030] FIG. 3 is a block diagram showing a partial configuration example of the base station 100 according to one aspect of the present disclosure. In the base station 100 shown in FIG. 3, a control unit 101 (corresponding to, for example, a control circuit) sets a first upper limit value of a frequency interval (for example, transmission Comb number) at which a first reference signal (for example, SRS) is arranged in a first bandwidth to be lower than a second upper limit value of a frequency interval at which a second reference signal (for example, SRS) is arranged in a second bandwidth wider than the first bandwidth. A receiving unit 105 (corresponding to, for example, a receiving circuit) receives the first reference signal based on the first upper limit value.

[0031] FIG. 4 is a block diagram showing a partial configuration example of the terminal 200 according to one aspect of the present disclosure. In the terminal 200 shown in FIG. 4, a control unit 203 (corresponding to, for example, a control circuit) sets a first upper limit value of a frequency interval (for example, transmission Comb number) at which a first reference signal (for example, SRS) is arranged in a first bandwidth to be lower than a second upper limit value of a frequency interval at which a second reference signal (for example, SRS) is arranged in a second bandwidth wider than the first bandwidth. A transmitting unit 206 (corresponding to, for example, a transmitting circuit) transmits the first reference signal based on the first upper limit value.

[0032] [Configuration of Base Station] FIG. 5 is a block diagram showing a configuration example of the base station 100 according to one aspect of the present disclosure. In FIG. 4, the base station 100 may include, for example, a control unit 101, an encoding / modulation unit 102, a transmission processing unit 103, a transmitting unit 104, a receiving unit 105, a reception processing unit 106, and a reference signal receiving unit 107.

[0033] The control unit 101 may, for example, control the scheduling of SRS. For example, the control unit 101 may generate SRS configuration information for the target terminal 200.

[0034] The SRS resource set of the SRS configuration information may include, for example, the transmission frequency band of each SRS resource (including, for example, the transmission bandwidth, the number of transmission Combs, or the frequency hopping pattern), the transmission symbol position, the number of SRS ports, the sequence number for reference signal generation, the cyclic shift amount (for example, the Cyclic Shift value), or parameters such as sequence hopping.

[0035] The control unit 101 may, for example, output control information including the generated SRS configuration information to the encoding / modulation unit 102. The SRS configuration information may be transmitted to the target terminal 200 after transmission processing is performed in the encoding / modulation unit 102, the transmission processing unit 103, and the transmission unit 104 as control information of the RRC layer (in other words, upper layer signaling or RRC signaling).

[0036] Also, the control unit 101 may, for example, control the reception of SRS based on the SRS configuration information. For example, the control unit 101 may output the SRS configuration information to the reception processing unit 106.

[0037] Also, the control unit 101 may, for example, generate allocation information for the frequency resources (for example, RBs) of the downlink data. The control unit 101 may, for example, output the allocation information for the radio resources for downlink data transmission to the transmission processing unit 103.

[0038] The encoding / modulation unit 102 may, for example, encode and modulate the SRS configuration information input from the control unit 101, and output the obtained modulated signal to the transmission processing unit 103.

[0039] The transmission processing unit 103 may form a transmission signal by, for example, mapping the modulation signal input from the encoding / modulation unit 102 according to the allocation information of the downlink data transmission radio resources input from the control unit 101 into a frequency band. For example, when the transmission signal is an orthogonal frequency division multiplexing (OFDM) signal, the transmission processing unit 103 may map the modulation signal to frequency resources, perform an inverse fast Fourier transform (IFFT) process to convert it into a time waveform, and add a cyclic prefix (CP) to form an OFDM signal.

[0040] The transmission unit 104 may perform transmission radio processing such as up-conversion and digital-to-analog (D / A) conversion on the transmission signal input from the transmission processing unit 103, and transmit the transmission signal after the transmission radio processing via an antenna.

[0041] The reception unit 105 may perform reception radio processing such as down-conversion and analog-to-digital (A / D) conversion on the radio signal received via the antenna, and output the reception signal after the reception radio processing to the reception processing unit 106.

[0042] The receiving processing unit 106 may, for example, identify a resource to which the SRS is mapped based on the SRS setting information input from the control unit 101, and extract a signal component mapped to the identified resource from the received signal. For example, in the case of Aperiodic SRS transmission, the receiving processing unit 106 may receive the SRS in a slot obtained by adding the slot offset set in the SRS resource set(s) to the transmission timing of the DCI. Also, for example, in the case of Semi-Persistent SRS transmission or Periodic SRS transmission, the receiving processing unit 106 may periodically receive the SRS in a slot specified by the transmission period and slot offset set in the SRS resource set. Further, the receiving processing unit 106 may, for example, identify the frequency resource of the SRS from the information on the transmission frequency band of the SRS resource included in the SRS setting information.

[0043] The receiving processing unit 106 may, for example, output the SRS to the reference signal receiving unit 107.

[0044] The reference signal receiving unit 107 may, for example, measure (or estimate) the reception quality (e.g., channel quality) of each frequency resource based on the SRS input from the receiving processing unit 106, and output information regarding the reception quality.

[0045] [Configuration of Terminal] FIG. 6 is a block diagram showing a configuration example of a terminal 200 according to an aspect of the present disclosure. In FIG. 6, the terminal 200 may include, for example, a receiving unit 201, a receiving processing unit 202, a control unit 203, a reference signal generating unit 204, a transmitting processing unit 205, and a transmitting unit 206.

[0046] The receiving unit 201 may perform reception radio processing such as down-conversion and analog-to-digital (A / D) conversion on the radio signal received via the antenna, and output the received signal after the reception radio processing to the receiving processing unit 202.

[0047] The reception processing unit 202 may, for example, extract the SRS setting information included in the reception signal input from the reception unit 201 and output it to the control unit 203. When the reception signal is an OFDM signal, the reception processing unit 202 may, for example, perform CP removal processing and Fourier transform (FFT: Fast Fourier Transform) processing.

[0048] The control unit 203 may, for example, control the transmission of SRS based on the SRS setting information input from the reception processing unit 202. For example, when the control unit 203 detects the SRS transmission timing from the SRS setting information, it specifies the SRS resource set used for the SRS transmission based on the SRS setting information. Then, the control unit 203 may, for example, extract the SRS resource information (including, for example, the transmission bandwidth, the number of transmission Combs, and the frequency hopping pattern) to be applied to the SRS based on the specified SRS resource set and output (or instruct or set) it to the reference signal generation unit 204 and the transmission processing unit 205. In the case of Aperiodic SRS transmission, the control unit 203 may, for example, detect the SRS transmission timing based on the SRS setting information and DCI (for example, trigger information).

[0049] When the reference signal generation unit 204 receives, for example, an instruction to generate a reference signal from the control unit 203, it may generate a reference signal (for example, SRS) based on the SRS resource information input from the control unit 203 and output it to the transmission processing unit 205.

[0050] The transmission processing unit 205 may, for example, map the SRS input from the reference signal generation unit 204 to the frequency resource instructed by the control unit 203. Thereby, a transmission signal is formed. When the transmission signal is an OFDM signal, the transmission processing unit 205 may, for example, perform IFFT processing on the signal after mapping to the frequency resource and add CP.

[0051] The transmission unit 206 may perform transmission radio processing such as up-conversion and digital-to-analog (D / A) conversion on the transmission signal formed in the transmission processing unit 205, and transmit the signal after the transmission radio processing via the antenna.

[0052] [Operations of Base Station 100 and Terminal 200] An operation example of the base station 100 and the terminal 200 having the above configuration will be described.

[0053] FIG. 7 is a sequence diagram showing an operation example of the base station 100 and the terminal 200.

[0054] The base station 100, for example, performs settings regarding the SRS for the terminal 200 (S101). For example, the base station 100 may generate SRS setting information regarding the setting of the SRS.

[0055] The base station 100 may transmit (or set or notify) the SRS setting information to the terminal 200 by upper layer signaling (for example, an RRC layer signal) (S102). Note that, for example, in the case of Aperiodic SRS transmission, the base station 100 may transmit trigger information to the terminal 200 by DCI (not shown).

[0056] The terminal 200, for example, generates an SRS based on the SRS setting information transmitted from the base station 100 (S103), and transmits the generated SRS to the base station 100 (S104). The base station 100 receives the SRS from the terminal 200 based on the SRS setting information transmitted to the terminal 200, for example.

[0057] [Method for Setting SRS Transmission Frequency Band] An example of a method for setting the transmission frequency band of the SRS resource included in the SRS setting information (for example, SRS resource set) in the base station 100 (for example, the control unit 101) will be described.

[0058] In this embodiment, for example, the upper limit value of the number of transmission Combs (in other words, the frequency interval at which SRS is arranged) that can be set for SRS at a certain transmission bandwidth (for example, a transmission bandwidth less than a threshold value (for example, 4RB)) may be set smaller than the upper limit value of the number of transmission Combs that can be set for SRS at a transmission bandwidth wider than the certain transmission bandwidth (for example, a transmission bandwidth greater than or equal to the threshold value). In other words, for SRS (for example, narrowband SRS) arranged at a transmission bandwidth less than a certain threshold value (for example, 4RB), the upper limit value of the number of transmission Combs that can be set (or used) for each transmission bandwidth may be restricted.

[0059] FIG. 8 is a diagram showing a setting example of the number of available transmission Combs for each SRS transmission bandwidth.

[0060] In FIG. 8, for example, for SRS with an SRS transmission bandwidth of 4RB or more, any of transmission Comb numbers = 2, 4, and 8 can be used (for example, the upper limit value of the transmission Comb number: 8).

[0061] On the other hand, in FIG. 8, for example, for SRS with an SRS transmission bandwidth less than 4RB, the upper limit value of the number of available transmission Combs may be set (in other words, restricted) to be smaller compared to SRS with an SRS transmission bandwidth of 4RB or more. For example, the upper limit value of the number of available transmission Combs for SRS with an SRS transmission bandwidth less than 4RB may be set according to the SRS transmission bandwidth.

[0062] For example, in FIG. 8, when the transmission bandwidth of SRS is 2RB, any of transmission Comb numbers = 2 and 4 can be used (for example, the upper limit value of the transmission Comb number: 4). Also, for example, in FIG. 8, when the transmission bandwidth of SRS is 1RB, transmission Comb number = 2 can be used (for example, the upper limit value of the transmission Comb number: 2). For example, as shown in FIG. 8, the narrower the SRS transmission bandwidth, the smaller the upper limit value of the number of available transmission Combs may be.

[0063] For example, as shown in FIG. 2 or Equation (1), in the SRS of each SRS transmission bandwidth, the longer the number of transmission Combs, the shorter the sequence length of the SRS generation sequence. Therefore, for example, as shown in FIG. 8, the narrower the SRS transmission bandwidth, the smaller the upper limit value of the available number of transmission Combs is set, so that a decrease in the lower limit value of the sequence length of the SRS generation sequence can be suppressed. Therefore, for example, even when the SRS transmission bandwidth is less than the threshold value, it is possible to suppress the sequence length from becoming shorter than a certain threshold value. In other words, even when the SRS transmission bandwidth is less than the threshold value, the lower limit value of the sequence length can be maintained at a certain threshold value or more.

[0064] FIG. 9 is a diagram showing an example of the relationship among the SRS transmission bandwidth, the number of transmission Combs, and the sequence length. In FIG. 9, as an example, the SRS transmission bandwidth and the number of transmission Combs may have the same relationship as that shown in FIG. 8. As shown in FIG. 9, the lower limit value of the sequence length of the SRS generation sequence corresponding to an SRS with an SRS transmission bandwidth less than the threshold value (for example, 4 RBs), such as 2 RBs or 1 RB, is 6 [sc]. In other words, in FIG. 9, even for an SRS with an SRS transmission bandwidth less than the threshold value (for example, 4 RBs), such as 2 RBs or 1 RB, it is possible to maintain the same lower limit value of the sequence length of the SRS generation sequence (for example, 6 [sc]) as that of an SRS with an SRS transmission bandwidth greater than or equal to the threshold value, such as 4 RBs.

[0065] Thereby, for example, an increase in the cross-correlation (or interference) between SRSs caused by the sequence length of the SRS generation sequence (in other words, the number of sequences that can be generated) can be suppressed, and a deterioration in the channel estimation accuracy of the SRS can be suppressed. In other words, for example, by maintaining the lower limit value of the sequence length at a certain threshold value or more, it becomes possible to generate more sequences having good PAPR characteristics or cross-correlation characteristics. Therefore, according to the present embodiment, for example, by increasing the number of transmission Combs for the SRS, a reduction in the channel estimation accuracy using the SRS can be suppressed, and the transmission power density of the SRS can be increased, so that the coverage performance of the SRS can be improved.

[0066] In this embodiment, in FIGS. 8 and 9, an example where the lower limit value of the sequence length for SRS generation is set to 6 [sc] has been described. However, the lower limit value of the sequence length is not limited to 6 [sc]. For example, the upper limit value of the transmission Comb number is not limited to the value shown in FIG. 8 or FIG. 9. FIGS. 10 and 11 are diagrams showing examples of other relationships among the SRS transmission bandwidth, the transmission Comb number, and the sequence length. In FIG. 10, for example, for an SRS with an SRS transmission bandwidth of less than 4 RBs, the upper limit value of the available transmission Comb number may be set smaller compared to the case of FIG. 8. As a result, for example, as shown in FIG. 11, the lower limit value of the sequence length for SRS generation is set (in other words, maintained) to a larger value of 12 [sc] compared to FIG. 9. Thereby, in FIGS. 10 and 11, for example, compared to the cases of FIGS. 8 and 9, it becomes easier to use an SRS with a long sequence length, and thus the channel estimation accuracy by the SRS can be improved.

[0067] Also, in this embodiment, in FIGS. 8 to 10, an example where the number of subcarriers per RB in Equation (1) is 12 (N sc RB = 12) has been described. However, the number of subcarriers per RB is not limited to 12 [sc / RB]. For example, when the number of subcarriers per RB is 6 [sc / RB], the sequence length becomes half of the sequence lengths shown in FIGS. 9 and 11, and the upper limit value of the available transmission Comb number is halved compared to FIGS. 8 and 10.

[0068] (Embodiment 2) In this embodiment, an example of frequency hopping of an SRS (for example, a narrowband SRS) arranged in a transmission bandwidth less than a certain threshold value (for example, 4 RBs) will be described.

[0069] [Frequency Hopping of Narrowband SRS] As described above, for example, the minimum transmission bandwidth of the NR SRS is 4 RBs, and the transmission bandwidth of the SRS may be a multiple of 4. Also, by performing N (N is an integer) times of frequency hopping for the narrowband SRS, the narrowband SRS may be transmitted in a sounding band that is N times the transmission bandwidth.

[0070] For example, in future NR, support for SRS with a transmission bandwidth of less than 4 RBs (e.g., 2 RBs or 1 RB) may also be assumed. In this case, for example, if a frequency hopping pattern with a granularity of 2 RBs or 1 RB is applied, a collision of SRS with a frequency hopping pattern with a granularity of 4 RBs may occur.

[0071] FIG. 12 is a diagram showing an example of a frequency hopping pattern. In FIG. 12, as an example, a frequency hopping pattern with a granularity of 2 RBs (in other words, in units of 2 RBs) is set for the SRS transmitted by UE#0, and a frequency hopping pattern with a granularity of 4 RBs (in other words, in units of 4 RBs) is set for the SRS transmitted by UE#1. In FIG. 12, for example, a collision of the SRS transmitted from each of UE#0 and UE#1 may occur at least in part of the SRS transmission timings of UE#0 and UE#1 respectively.

[0072] Due to the collision of SRS, interference between SRSs may occur, and thus the channel estimation accuracy by SRS may deteriorate.

[0073] Therefore, in this embodiment, an example of setting a frequency hopping pattern in narrowband SRS will be described.

[0074] The configuration example of the base station and the terminal according to this embodiment may be the same as that of Embodiment 1 for other functions, for example, except that some functions are different from those of Embodiment 1.

[0075] [Configuration of Base Station] In the base station 100 according to this embodiment, the control unit 101 may set, for example, the frequency hopping pattern of the SRS arranged in each transmission bandwidth. For example, the control unit 101 may set a frequency hopping pattern in which frequency resources do not collide between the frequency hopping pattern applied to the SRS (for example, narrowband SRS) whose transmission bandwidth is less than the threshold and the frequency hopping pattern applied to the SRS (for example, narrowband SRS) whose transmission bandwidth is greater than or equal to the threshold. The control unit 101 may output, for example, the SRS setting information including the set frequency hopping pattern to the encoding / modulation unit 102 and the reception processing unit 106.

[0076] The reception processing unit 106 may, for example, identify the resource to which the SRS is mapped based on the SRS setting information (for example, including the frequency hopping pattern) input from the control unit 101, and extract the signal component (for example, SRS) mapped to the identified resource from the reception signal input from the reception unit 105.

[0077] Other processes in the base station 100 may be the same as those in the first embodiment.

[0078] [Configuration of the terminal] The terminal 200 according to this embodiment may map and transmit the SRS to the resource instructed to transmit the SRS based on, for example, the SRS setting information (for example, including the frequency hopping pattern) from the base station 100.

[0079] [Example of setting the frequency hopping pattern of narrowband SRS] An example of setting the frequency hopping pattern applied to the SRS resource included in the SRS setting information (for example, SRS resource set) generated in the base station 100 (for example, the control unit 101) will be described.

[0080] In the present embodiment, for example, in the frequency hopping pattern of the narrowband SRS arranged in a transmission bandwidth less than a threshold value (e.g., 4RB), the SRS may be transmitted in a part of the transmission band set by the frequency hopping pattern of the SRS arranged in the transmission bandwidth of the threshold value (e.g., 4RB).

[0081] For example, the base station 100 and the terminal 200 may control the frequency hopping of the SRS with a transmission bandwidth less than the threshold value in units of the transmission band (e.g., 4RB) where the SRS with the transmission bandwidth of the threshold value is arranged for each slot.

[0082] Hereinafter, Example 1 and Example 2 of the frequency hopping pattern setting will be described.

[0083] <Example 1> FIGS. 13 and 14 are diagrams showing a setting example of the frequency hopping pattern of the narrowband SRS.

[0084] In FIGS. 13 and 14, the base station 100 and the terminal 200 may control the frequency hopping (e.g., frequency hopping between slots) of the narrowband SRS (e.g., the SRS of UE#0) with a transmission bandwidth less than the threshold value (e.g., 4RB) in units of the transmission band of the SRS arranged in the transmission bandwidth corresponding to the threshold value (e.g., 4RB unit).

[0085] Also, in FIGS. 13 and 14, the base station 100 and the terminal 200 may control the frequency hopping between a plurality of SRS symbols in which the SRS is arranged within a slot in the frequency hopping pattern of the narrowband SRS with a transmission bandwidth less than the threshold value (e.g., the frequency hopping pattern set for UE#0).

[0086] For example, in FIG. 13, for the SRS transmitted by UE#0, a frequency hopping pattern with a 2RB granularity (in other words, the transmission bandwidth is less than the threshold) is set, and for the SRS transmitted by UE#1, a frequency hopping pattern with a 4RB granularity (in other words, the transmission bandwidth is greater than or equal to the threshold) is set. In FIG. 13, for example, a narrowband SRS of 2RB may be arranged in 2 symbols within a slot and frequency-hopped within a 4RB band in the slot. Also, as shown in FIG. 13, the SRS arranged in 2 symbols within each slot may be frequency-hopped in units of 4RB between slots.

[0087] Also, for example, in FIG. 14, for the SRS transmitted by UE#0, a frequency hopping pattern with a 1RB granularity (in other words, the transmission bandwidth is less than the threshold) is set, and for the SRS transmitted by UE#1, a frequency hopping pattern with a 4RB granularity (in other words, the transmission bandwidth is greater than or equal to the threshold) is set. In FIG. 14, for example, a narrowband SRS of 1RB may be arranged in 4 symbols within a slot and frequency-hopped within a 4RB band in the slot. Also, as shown in FIG. 14, the SRS arranged in 4 symbols within each slot may be frequency-hopped in units of 4RB between slots.

[0088] In FIGS. 13 and 14, the 4RB band in which frequency hopping occurs within a slot (in other words, the hopping unit of frequency hopping between slots) may be one of the bands determined based on the frequency hopping pattern of the NR SRS (or the SRS whose transmission bandwidth corresponds to the threshold). For example, as shown in FIGS. 13 and 14, the total transmission bandwidth (for example, 4RB) of a plurality of SRSs each frequency-hopped between symbols within a slot in UE#0 is the same as the transmission bandwidth (for example, 4RB) of the SRS arranged in each slot in UE#1. Also, as shown in FIGS. 13 and 14, in each slot, the transmission band in which the SRS of UE#0 is arranged and the transmission band in which the SRS of UE#1 is arranged may be different.

[0089] By setting this frequency hopping pattern, for example, the frequency hopping pattern of a narrowband SRS with a transmission bandwidth less than a threshold value (e.g., 4RB) and the frequency hopping pattern of a narrowband SRS with a transmission bandwidth greater than or equal to the threshold value (e.g., 4RB) are orthogonally multiplexed in the frequency domain. Therefore, even when different frequency hopping patterns with different granularities are applied to different terminals 200, the occurrence of SRS collisions can be suppressed.

[0090] Also, for example, since frequency hopping is applied between symbols within a slot for a narrowband SRS with a transmission bandwidth less than a threshold value (e.g., 4RB), the hopping period (or frequency hopping cycle) can be reduced. For example, in FIGS. 13 and 14, the hopping period of the SRS with a transmission bandwidth less than the threshold value is 4 slots.

[0091] Note that in FIGS. 13 and 14, as an example, in the frequency hopping between symbols within a slot, the case where a pattern is set such that the SRS of a symbol slower in the time domain is arranged in a higher band in the frequency domain has been described, but the frequency hopping pattern between symbols within a slot is not limited to this.

[0092] <Example 2> FIG. 15 is a diagram showing an example of setting the frequency hopping pattern of a narrowband SRS.

[0093] In FIG. 15, the base station 100 and the terminal 200 control the frequency hopping of a narrowband SRS (e.g., the SRS of UE#0) with a transmission bandwidth less than a threshold value (e.g., 4RB) for each frequency hopping period of the SRS corresponding to the threshold value (e.g., every slot). Also, as shown in FIG. 15, in the frequency hopping pattern of the narrowband SRS with a transmission bandwidth less than the threshold value (e.g., the frequency hopping pattern for UE#0), the SRS may be frequency-hopped in units of the transmission bandwidth of the SRS corresponding to the threshold value (e.g., 4RB units).

[0094] For example, in FIG. 15, for the SRS transmitted by UE#0, a frequency hopping pattern with a 2RB granularity (in other words, the transmission bandwidth is less than the threshold) is set, and for the SRS transmitted by UE#1, a frequency hopping pattern with a 4RB granularity (in other words, the transmission bandwidth is greater than or equal to the threshold) is set. In FIG. 15, for example, a narrowband SRS of 2RB may be arranged in one symbol within a slot and frequency-hopped in units of 4RB between slots (for example, the same transmission bandwidth unit as the SRS of UE#1).

[0095] As shown in FIG. 15, the hopping period (or frequency hopping cycle) of the narrowband SRS of 2RB is 8 slots.

[0096] Note that, for example, a frequency hopping pattern may be similarly set for an SRS with a transmission bandwidth of 1RB (not shown). The hopping period of the narrowband SRS of 1RB is, for example, 16 slots.

[0097] In FIG. 15, the 4RB band in which frequency hopping of the SRS with a transmission bandwidth less than the threshold is performed (in other words, the hopping unit of frequency hopping between slots) may be one of the bands determined based on the frequency hopping pattern of the NR SRS (or the SRS with a transmission bandwidth corresponding to the threshold). For example, as shown in FIG. 15, in each slot, the transmission band where the SRS of UE#0 is arranged and the transmission band where the SRS of UE#1 is arranged may be different.

[0098] With this setting of the frequency hopping pattern, for example, the frequency hopping pattern of the narrowband SRS with a transmission bandwidth less than the threshold (for example, 4RB) and the frequency hopping pattern of the narrowband SRS with a transmission bandwidth greater than or equal to the threshold (for example, 4RB) are orthogonally multiplexed in the frequency domain. Therefore, even when different granularity frequency hopping patterns are applied to different terminals 200, the occurrence of collisions between SRSs can be suppressed.

[0099] For example, compare Example 1 and Example 2.

[0100] In Example 1, compared with Example 2, the hopping period of the SRS with a transmission bandwidth less than the threshold can be set shorter. In other words, in Example 1, for example, it is possible to maintain a hopping period similar to that of the SRS with a transmission bandwidth greater than or equal to the threshold.

[0101] On the other hand, in Example 2, compared with Example 1, the amount of SRS resources arranged in each slot can be reduced.

[0102] As described above, the setting example of the frequency hopping pattern of the narrowband SRS has been explained.

[0103] In the present embodiment, in the frequency hopping pattern of the narrowband SRS with a transmission bandwidth less than the threshold (for example, 4RB), the SRS is transmitted in at least a part of the transmission band set by the frequency hopping pattern of the SRS corresponding to the threshold (for example, 4RB). In other words, the frequency hopping pattern of the narrowband SRS with a bandwidth less than the threshold may reuse the setting (in other words, the mechanism, for example, the hopping unit) of the frequency hopping pattern of the SRS corresponding to the threshold.

[0104] Thereby, in the present embodiment, in the frequency hopping pattern of the narrowband SRS with a transmission bandwidth less than the threshold and the frequency hopping pattern of the narrowband SRS with a transmission bandwidth greater than or equal to the threshold, the SRSs can be orthogonal multiplexed in the frequency domain, so that the occurrence of collisions between SRSs can be suppressed. Therefore, according to the present embodiment, the interference between SRSs can be suppressed, and the channel estimation accuracy by the SRS can be improved.

[0105] As described above, one embodiment of the present disclosure has been described.

[0106] In one embodiment of the present disclosure, although the case where the SRS setting information is set in the terminal 200 by upper layer signaling (for example, signaling of the RRC layer) has been described, the setting of the SRS setting information is not limited to upper layer signaling, and other signaling (for example, physical layer signaling) may also be used.

[0107] Also, in one embodiment of the present disclosure, the target for notifying resources such as the transmission bandwidth and the number of transmission Combs is not limited to reference signals such as SRS, and other signals (or information) may also be used. For example, one embodiment of the present disclosure may be applied to a response signal for data (also referred to as ACK / NACK or HARQ-ACK for example) instead of SRS.

[0108] Also, in one embodiment of the present disclosure, parameters such as candidates for SRS resources (for example, combinations of transmission bandwidth, number of transmission Combs, and sequence length), threshold values (for example, 4 RBs), upper limit values of the number of transmission Combs, or frequency hopping granularity (for example, 1 RB, 2 RBs, or 4 RBs), and the number of subcarriers per RB are not limited to the examples described above, and other values may also be used.

[0109] (Control signal) In one embodiment of the present disclosure, the downlink control signal (or downlink control information) may be, for example, a signal (or information) transmitted in the Physical Downlink Control Channel (PDCCH) of the physical layer, or a signal (or information) transmitted in the Medium Access Control (MAC) or Radio Resource Control (RRC) of the upper layer. Also, the signal (or information) is not limited to being notified by the downlink control signal, and may be predefined in the specification (or standard), or preset in the base station and the terminal.

[0110] In one embodiment of the present disclosure, the uplink control signal (or uplink control information) may be, for example, a signal (or information) transmitted in the physical layer PDCCH, or a signal (or information) transmitted in the upper layer MAC or RRC. Further, the signal (or information) is not limited to being notified by the uplink control signal, and may be predefined in the specification (or standard), or may be preset in the base station and the terminal. Further, the uplink control signal may be replaced with, for example, uplink control information (UCI), first stage sidelink control information (SCI), or second stage SCI.

[0111] (Base station) In one embodiment of the present disclosure, the base station may be a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a parent device, a gateway, or the like. Further, in sidelink communication, it may be a terminal instead of the base station. Further, instead of the base station, it may be a relay device that relays communication between the upper node and the terminal.

[0112] (Uplink / Downlink / Sidelink) One embodiment of the present disclosure may be applied to, for example, any of the uplink, downlink, and sidelink. For example, one embodiment of the present disclosure may be applied to the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), Physical Random Access Channel (PRACH) of the uplink, the Physical Downlink Shared Channel (PDSCH), PDCCH, Physical Broadcast Channel (PBCH) of the downlink, or the Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), Physical Sidelink Broadcast Channel (PSBCH) of the sidelink.

[0113] Note that each of PDCCH, PDSCH, PUSCH, and PUCCH is an example of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. Also, PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel, respectively. Also, PBCH and PSBCH are notification (broadcast) channels, and PRACH is an example of a random access channel.

[0114] (Data Channel / Control Channel) One embodiment of the present disclosure may be applied to, for example, either a data channel or a control channel. For example, the channel in one embodiment of the present disclosure may be replaced with any of PDSCH, PUSCH, PSSCH of the data channel, or PDCCH, PUCCH, PBCH, PSCCH, PSBCH of the control channel.

[0115] (Reference Signal) In one embodiment of the present disclosure, the reference signal is a signal known to both, for example, a base station and a mobile station, and may also be referred to as a Reference Signal (RS) or a pilot signal. The reference signal may be any of a Demodulation Reference Signal (DMRS), a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), or a Sounding Reference Signal (SRS).

[0116] (Time interval) In one embodiment of the present disclosure, the unit of time resource is not limited to one or a combination of a slot and a symbol. For example, it may be a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot subslot, a minislot, or a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier - Frequency Division Multiplexing (SC-FDMA) symbol, or other time resource units. Also, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above-described embodiments, and other numbers of symbols may also be used.

[0117] (Frequency band) One embodiment of the present disclosure may be applied to either a licensed band or an unlicensed band.

[0118] (Communication) One embodiment of the present disclosure may be applied to any of communication between a base station and a terminal, communication between terminals (Sidelink communication, Uu link communication), and Vehicle to Everything (V2X) communication. For example, the channel in one embodiment of the present disclosure may be replaced by any one of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, or PBCH.

[0119] In addition, one embodiment of the present disclosure may be applied to any of a terrestrial network, a satellite, or a non-terrestrial network (NTN: Non-Terrestrial Network) using a high-altitude pseudo satellite (HAPS: High Altitude Pseudo Satellite). Further, one embodiment of the present disclosure may be applied to a terrestrial network with a large cell size, a very wideband transmission network, etc., where the transmission delay is large compared to the symbol length and slot length.

[0120] (Antenna port) In one embodiment of the present disclosure, an antenna port refers to a logical antenna (antenna group) composed of one or more physical antennas. For example, an antenna port does not necessarily refer to one physical antenna, and may refer to an array antenna composed of a plurality of antennas. For example, it is not specified how many physical antennas an antenna port is composed of, and it may be defined as the minimum unit capable of transmitting a reference signal by a terminal station. Also, an antenna port may be defined as the minimum unit for multiplying the weighting of a precoding vector.

[0121] <5G NR System Architecture and Protocol Stack> 3GPP is continuing its work towards the next release of 5th generation mobile phone technology (also simply referred to as "5G"), which includes the development of new radio access technology (NR) operating in the frequency range up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, enabling the prototyping and commercial deployment of terminals (e.g., smartphones) compliant with the 5G NR standard.

[0122] For example, the system architecture generally assumes an NG-RAN (Next Generation - Radio Access Network) with gNBs. The gNB provides the UE-side termination of the protocols for the user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) of NG radio access. The gNBs are connected to each other by the Xn interface. Also, the gNB is connected to the NGC (Next Generation Core) by the Next Generation (NG) interface, more specifically to the AMF (Access and Mobility Management Function) (e.g., a specific core entity performing AMF) by the NG-C interface, and to the UPF (User Plane Function) (e.g., a specific core entity performing UPF) by the NG-U interface. The NG-RAN architecture is shown in Figure 16 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0123] The protocol stack of the user plane of NR (see, for example, 3GPP TS 38.300, section 4.4.1) includes the PDCP (Packet Data Convergence Protocol, see section 6.4 of TS 38.300) sublayer, the RLC (Radio Link Control, see section 6.3 of TS 38.300) sublayer, and the MAC (Medium Access Control, see section 6.2 of TS 38.300) sublayer, which are terminated at the network side in the gNB. Also, a new sublayer of the access stratum (AS), the SDAP (Service Data Adaptation Protocol), is introduced above the PDCP (see, for example, section 6.5 of 3GPP TS 38.300). In addition, the protocol stack of the control plane is defined for NR (see, for example, TS 38.300, section 4.4.2). An overview of the layer 2 functions is described in section 6 of TS 38.300. The functions of the PDCP sublayer, the RLC sublayer, and the MAC sublayer are listed in sections 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in section 7 of TS 38.300.

[0124] For example, the Medium-Access-Control layer handles multiplexing of logical channels and scheduling and scheduling-related functions that handle various numerologies.

[0125] For example, the physical layer (PHY) is responsible for encoding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. Also, the physical layer handles the mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for the transmission of a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include, as uplink physical channels, PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel), PUCCH (Physical Uplink Control Channel), and as downlink physical channels, PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), PBCH (Physical Broadcast Channel).

[0126] The use cases / deployment scenarios of NR may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC), which have diverse requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps in the downlink and 10 Gbps in the uplink) and effective (user-experienced) data rates that are about three times the data rates provided by IMT-Advanced. On the other hand, in the case of URLLC, more stringent requirements are imposed for ultra-low latency (0.5 ms for both UL and DL in terms of user plane latency) and high reliability (1 - 10-5 within 1 ms). Finally, for mMTC, a high connection density (1,000,000 devices / km2 in urban environments), wide coverage in harsh environments, and extremely long-lived batteries (15 years) for low-cost devices may be required.

[0127] Therefore, the new numerology of OFDM suitable for one use case (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) may not be effective for other use cases. For example, in a low-latency service, preferably, the symbol length is shorter (and thus the subcarrier spacing is larger) and / or the number of symbols per scheduling interval (also referred to as TTI) is smaller than that of mMTC services. Further, in a deployment scenario with a large channel delay spread, preferably, the CP length is longer than that in a scenario with a short delay spread. The subcarrier spacing may be optimized according to the situation so that a similar CP overhead is maintained. The value of the subcarrier spacing supported by NR may be one or more. Correspondingly, currently, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz... are considered. The symbol length Tu and the subcarrier spacing Δf are directly related by the formula Δf = 1 / Tu. Similar to the LTE system, the term "resource element" can be used to mean the smallest resource unit composed of one subcarrier with respect to the length of one OFDM / SC-FDMA symbol.

[0128] In the new radio system 5G-NR, for each numerology and each carrier, a resource grid of subcarriers and OFDM symbols is defined for each of the uplink and the downlink. Each element of the resource grid is called a resource element and is identified based on the frequency index in the frequency domain and the symbol position in the time domain (see 3GPP TS 38.211 v15.6.0).

[0129] <Functional Separation between NG-RAN and 5GC in 5G NR> Figure 17 shows the functional separation between NG-RAN and 5GC. The logical nodes of NG-RAN are gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0130] For example, gNB and ng-eNB host the following main functions: - Functions of radio resource management such as radio bearer control, radio admission control, connection mobility control, and dynamic allocation (scheduling) of resources to the UE in both the uplink and downlink; - IP header compression, encryption, and integrity protection of data; - Selection of the AMF at the time of UE attachment when the AMF cannot be determined from the information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards the AMF; - Setup and release of connections; - Scheduling and transmission of paging messages; - Scheduling and transmission of system information messages (source is the AMF or the operation, administration, and maintenance function (OAM)); - Configuration of measurements and measurement reports for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; - Support for network slicing; - Management of QoS flows and mapping to data radio bearers; - Support for UEs in the RRC_INACTIVE state; - Delivery function of NAS messages; - Sharing of radio access networks; - Dual connectivity; - Tight cooperation between NR and E-UTRA.

[0131] The Access and Mobility Management Function (AMF) hosts the following main functions: - Function to terminate Non-Access Stratum (NAS) signaling; - Security of NAS signaling; - Access Stratum (AS) security control; - Core Network (CN) node - to - node signaling for mobility between 3GPP access networks; - Reachability of idle - mode UEs (including control and execution of paging re - transmission); - Management of registration areas; - Support for in - system mobility and inter - system mobility; - Access authentication; - Access authorization including roaming rights check; - Mobility management control (subscription and policy); - Support for network slicing; - Selection of Session Management Function (SMF).

[0132] Furthermore, the User Plane Function (UPF) hosts the following main functions: - Anchor point for intra - RAT mobility / inter - RAT mobility (if applicable); - External PDU (Protocol Data Unit) session point for interconnection with data networks; - Packet routing and forwarding; - Packet inspection and enforcement of policy rules in the user plane part; - Reporting of traffic usage; - Uplink classifier to support routing of traffic flows to data networks - Branching Point for supporting multi-homed PDU session; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Verification of uplink traffic (mapping to the QoS flow of the SDF); - Downlink packet buffering and triggering function for downlink data notification.

[0133] Finally, the Session Management Function (SMF) hosts the following main functions: - Session management; - IP address allocation and management for the UE; - Selection and control of the UPF; - Traffic steering setting function in the User Plane Function (UPF) for routing traffic to the appropriate destination; - Enforcement of control part policies and QoS; - Notification of downlink data.

[0134] <Procedures for RRC connection setup and reconfiguration> Figure 18 shows some of the interactions between the UE, gNB, and AMF (5GC entity) in the NAS part when the UE moves from RRC_IDLE to RRC_CONNECTED (see TS 38.300 v15.6.0).

[0135] RRC is the upper layer signaling (protocol) used for the configuration of the UE and gNB. With this transition, the AMF prepares the UE context data (which includes, for example, PDU session context, security keys, UE Radio Capability, UE Security Capabilities, etc.) and sends it to the gNB together with the INITIAL CONTEXT SETUP REQUEST. Then, the gNB activates the AS security with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE and the UE responding to the gNB with a SecurityModeComplete message. After that, the gNB sends an RRCReconfiguration message to the UE, and upon receiving the RRCReconfigurationComplete from the UE, performs the reconfiguration for setting up the Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For a signaling-only connection, since the SRB2 and DRB are not set up, the steps related to RRCReconfiguration are skipped. Finally, the gNB notifies the AMF in the INITIAL CONTEXT SETUP RESPONSE that the setup procedure is complete.

[0136] Therefore, in the present disclosure, there is provided an entity (e.g., AMF, SMF, etc.) of a 5th Generation Core (5GC) including a control circuit that establishes a Next Generation (NG) connection with a gNodeB during operation, and a transmission unit that transmits an initial context setup message to the gNodeB via the NG connection during operation so that a signaling radio bearer between the gNodeB and a user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling including a resource allocation setting information element (IE) to the UE via the signaling radio bearer. Then, the UE performs transmission on the uplink or reception on the downlink based on the resource allocation setting.

[0137] <IMT Usage Scenarios After 2020> FIG. 19 shows some of the use cases for 5G NR. In the 3rd generation partnership project new radio (3GPP NR), three use cases envisioned by IMT-2020 to support a variety of services and applications are being considered. The formulation of the first-phase specifications for enhanced mobile-broadband (eMBB) has been completed. Current and future work includes, in addition to expanding the support for eMBB, standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC). FIG. 19 shows some examples of the envisioned usage scenarios of IMT after 2020 (see, for example, ITU-R M.2083, FIG. 2).

[0138] URLLC use cases have strict requirements for performance such as throughput, latency (delay), and availability. The URLLC use case is envisioned as one of the enabling technologies to realize these future applications such as wireless control of industrial production processes or manufacturing processes, remote medical surgery, automation of power transmission and distribution in smart grids, and traffic safety. The ultra-high reliability of URLLC is supported by identifying technologies that meet the requirements set by TR 38.913. In NR URLLC in Release 15, an important requirement is that the target user plane latency is 0.5 ms in UL (uplink) and 0.5 ms in DL (downlink). The general URLLC requirement for a single packet transmission is that when the user plane latency is 1 ms, the block error rate (BLER) is 1E-5 for a packet size of 32 bytes.

[0139] From the perspective of the physical layer, reliability can be improved in many ways. The current room for reliability improvement includes defining a separate CQI table for URLLC, a more compact DCI format, repetition of PDCCH, etc. However, this room can expand for the realization of ultra-high reliability as NR becomes more stable and more developed (regarding the important requirements of NR URLLC). Specific use cases of NR URLLC in Release 15 include extended reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0140] In addition, the technical enhancements targeted by NR URLLC aim to improve latency and reliability. Technical enhancements for latency improvement include configurable numerology, non-slot-based scheduling by flexible mapping, grant-free uplink (configured grant), slot-level repetition in the data channel, and pre-emption in the downlink. Pre-emption means that a transmission for which resources have already been allocated is stopped, and the already allocated resources are used for another transmission with lower latency / higher priority requirements requested later. Therefore, an already permitted transmission is replaced by a later transmission. Pre-emption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be replaced by a transmission of service type B (eMBB, etc.). Technical enhancements for reliability improvement include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0141] The characteristics of the use cases of mMTC (massive machine type communication) are typically that there are a very large number of connected devices that transmit relatively small amounts of data and are less affected by latency. The devices are required to be low-cost and have a very long battery life. From the perspective of NR, using a very narrow bandwidth portion is one solution that can save power as seen from the UE and enable a long battery life.

[0142] As described above, the scope of reliability improvement in NR is expected to be broader. One of the important requirements for all cases, for example, the important requirements for URLLC and mMTC are high reliability or ultra-high reliability. Several mechanisms can improve reliability from the wireless perspective and the network perspective. Generally, there are two to three important areas that may help improve reliability. These areas include compact control channel information, repetition of data channels / control channels, and diversity regarding the frequency domain, time domain, and / or spatial domain. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0143] Regarding NR URLLC, further use cases with more stringent requirements, such as factory automation, transportation, and power distribution, are envisioned. The stringent requirements are high reliability (reliability up to the 10-6 level), high availability, packet size up to 256 bytes, time synchronization up to about several μs (depending on the use case, the value can be 1 μs or several μs according to the frequency range and short latency of about 0.5 ms to 1 ms, for example, 0.5 ms latency in the target user plane), and short latency of about 0.5 ms to 1 ms (for example, 0.5 ms latency in the target user plane).

[0144] Furthermore, for NR URLLC, several technical enhancements may be available from the perspective of the physical layer. These technical enhancements include enhancements to the PDCCH (Physical Downlink Control Channel) related to compact DCI, repetition of the PDCCH, and increased monitoring of the PDCCH. Also, the enhancement of UCI (Uplink Control Information) is related to the enhancement of enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback. Additionally, there may be enhancements to the PUSCH related to mini-slot level hopping, and enhancements to retransmission / repetition. The term "mini-slot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot has 14 symbols).

[0145] <QoS Control> The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR: Guaranteed Bit Rate QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Therefore, at the NAS level, a QoS flow is the finest-grained QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI) that is carried in an encapsulation header via the NG-U interface.

[0146] For each UE, the 5GC establishes one or more PDU sessions. For each UE, in accordance with the PDU session, the NG-RAN establishes at least one Data Radio Bearer (DRB) as shown above with reference to, for example, Figure 18. Also, additional DRBs for the QoS flows of that PDU session can be configured later (it depends on the NG-RAN when to configure). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. While NAS-level packet filters in the UE and 5GC associate UL packets and DL packets with QoS flows, AS-level mapping rules in the UE and NG-RAN associate UL QoS flows and DL QoS flows with DRBs.

[0147] Figure 20 shows the 5G NR non-roaming reference architecture (see TS 23.501 v16.1.0, section 4.23). The Application Function (AF) (for example, an external application server hosting 5G services as illustrated in Figure 19) communicates with the 3GPP core network to provide services. For example, accessing the Network Exposure Function (NEF) or communicating with the policy framework (see Policy Control Function (PCF)) for policy control (such as QoS control) to support applications that affect traffic routing. Based on operator deployment, Application Functions considered to be trusted by the operator can communicate directly with the relevant Network Functions. Application Functions not permitted by the operator to directly access Network Functions communicate with the relevant Network Functions using the external exposure framework via the NEF.

[0148] Figure 20 further shows additional functional units of the 5G architecture, namely, the Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN, e.g., operator services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and operate in a cloud computing environment.

[0149] Therefore, in the present disclosure, in operation, a request including QoS requirements for at least one of the URLLC service, eMMB service, and mMTC service is transmitted to at least one of the functions of the 5GC (e.g., NEF, AMF, SMF, PCF, UPF, etc.) to establish a PDU session including a radio bearer between the gNodeB and the UE according to the QoS requirements. An application server (e.g., the AF of the 5G architecture) is provided, which includes a transmission unit for transmitting the request and a control circuit for providing services using the established PDU session in operation.

[0150] The present disclosure can be implemented by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiments can be realized, partially or entirely, as an LSI which is an integrated circuit, and each process described in the above embodiments can be controlled, partially or entirely, by one LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip so as to include part or all of the functional blocks. The LSI may be provided with data input and output. Depending on the degree of integration, the LSI may also be referred to as an IC, a system LSI, a super LSI, or an ultra LSI.

[0151] The method of integrating into an integrated circuit is not limited to LSI, and it may also be realized by an application specific circuit, a general-purpose processor, or a dedicated processor. Further, after manufacturing the LSI, an FPGA (Field Programmable Gate Array) which can be programmed, or a reconfigurable processor which can reconfigure the connection and setting of circuit cells inside the LSI may be used. The present disclosure may be realized as digital processing or analog processing.

[0152] Furthermore, if an integrated circuit technology replacing the LSI appears due to the progress of semiconductor technology or other derived technologies, naturally, the technology may be used to integrate the functional blocks. The application of biotechnology, etc. may be possible.

[0153] The present disclosure can be implemented in any type of apparatus, device, system (collectively referred to as a communication device) having a communication function. The communication device may include a wireless transceiver (transceiver) and a processing / control circuit. The wireless transceiver may include a receiving unit and a transmitting unit, or may include them as functions. The wireless transceiver (transmitting unit, receiving unit) may include an RF (Radio Frequency) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (mobile phones, smartphones, etc.), tablets, personal computers (PCs) (laptops, desktops, notebooks, etc.), cameras (digital still / video cameras, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smartwatches, tracking devices, etc.), game consoles, digital book readers, telehealth / telemedicine (remote healthcare / medical prescription) devices, vehicles or mobile transportation means with communication functions (automobiles, airplanes, ships, etc.), and combinations of the above various devices.

[0154] The communication device is not limited to portable or movable ones, and includes any type of apparatus, device, system that is not portable or is fixed, for example, smart home devices (home appliances, lighting devices, smart meters or measuring devices, control panels, etc.), vending machines, and any "Things" that can exist on other IoT (Internet of Things) networks.

[0155] Communication includes data communication by a cellular system, a wireless LAN system, a communication satellite system, etc., and also includes data communication by combinations of these.

[0156] In addition, the communication device also includes devices such as a controller and a sensor that are connected or coupled to a communication device that executes the communication function described in the present disclosure. For example, a controller and a sensor that generate control signals and data signals used by the communication device that executes the communication function of the communication device are included.

[0157] In addition, the communication device includes infrastructure facilities that communicate with or control the above-described various non-limiting devices, such as base stations, access points, and any other devices, devices, and systems.

[0158] A terminal according to an embodiment of the present disclosure includes a control circuit that sets a first upper limit value of a frequency interval at which a first reference signal is arranged in a first bandwidth to be smaller than a second upper limit value of a frequency interval at which a second reference signal is arranged in a second bandwidth wider than the first bandwidth, and a transmission circuit that transmits the first reference signal based on the first upper limit value.

[0159] In an embodiment of the present disclosure, the control circuit controls frequency hopping of the first reference signal in units of a transmission band in which the second reference signal is arranged for each unit time interval.

[0160] In an embodiment of the present disclosure, the control circuit controls frequency hopping of the first reference signal between a plurality of symbols in which a plurality of the first reference signals are arranged within the unit time interval.

[0161] In an embodiment of the present disclosure, the control circuit controls frequency hopping of the first reference signal for each frequency hopping period of the second reference signal.

[0162] In an embodiment of the present disclosure, the first bandwidth is less than a threshold value, the second bandwidth is greater than or equal to the threshold value, and the threshold value is 4 resource blocks.

[0163] In an embodiment of the present disclosure, when the first bandwidth is 2 resource blocks, the first upper limit value is 4 subcarriers or less.

[0164] In one embodiment of the present disclosure, when the first bandwidth is 1 resource block, the first upper limit value is 2 sub-carriers or less.

[0165] A base station according to an embodiment of the present disclosure includes a control circuit that sets a first upper limit value of a frequency interval at which a first reference signal is arranged in a first bandwidth to be smaller than a second upper limit value of a frequency interval at which a second reference signal is arranged in a second bandwidth wider than the first bandwidth, and a reception circuit that receives the first reference signal based on the first upper limit value.

[0166] In a communication method according to an embodiment of the present disclosure, a terminal sets a first upper limit value of a frequency interval at which a first reference signal is arranged in a first bandwidth to be smaller than a second upper limit value of a frequency interval at which a second reference signal is arranged in a second bandwidth wider than the first bandwidth, and transmits the first reference signal based on the first upper limit value.

[0167] In a communication method according to an embodiment of the present disclosure, a base station sets a first upper limit value of a frequency interval at which a first reference signal is arranged in a first bandwidth to be smaller than a second upper limit value of a frequency interval at which a second reference signal is arranged in a second bandwidth wider than the first bandwidth, and receives the first reference signal based on the first upper limit value.

[0168] The disclosure contents of the specification, drawings, and abstract included in Japanese Application No. 2020-121431 filed on July 15, 2020 are all incorporated herein by reference.

Industrial Applicability

[0169] One embodiment of the present disclosure is useful for a wireless communication system.

Explanation of Signs

[0170] 100 Base station 101, 203 Control unit 102 Encoding / modulation unit 103, 205 Transmission processing unit 104,206 Transmission unit 105,201 Receiver 106,202 Reception processing unit 107 Reference signal receiver 200 Terminal 204 Reference signal generation unit

Claims

1. A control circuit that determines the sequence length of a reference signal based on the number of transmission Combs, and a transmitter that transmits the reference signal generated with the sequence length, wherein the bandwidth of the reference signal can be selected from a plurality of bandwidths including a first bandwidth and a second bandwidth, and a first lower limit value of the sequence length in the first bandwidth is the same as a second lower limit value of the sequence length in the second bandwidth, A terminal.

2. A first upper limit value of the number of transmission Combs in the first bandwidth is smaller than a second upper limit value of the number of transmission Combs in the second bandwidth, The terminal according to Claim 1.

3. The first bandwidth is smaller than the second bandwidth, The terminal according to Claim 1.

4. The longer the number of transmission Combs, the shorter the sequence length of the reference signal, The terminal according to Claim 1.

5. The first bandwidth is less than 4 resource blocks, and the second bandwidth is 4 resource blocks or more, The terminal according to Claim 1.

6. When the first bandwidth is 4 resource blocks and the second bandwidth is 2 resource blocks, a first upper limit value of the number of transmission Combs in the first bandwidth is 8, and a second upper limit value of the number of transmission Combs in the second bandwidth is 4, The terminal according to Claim 1.

7. The reference signal is transmitted using a first frequency hopping in the first bandwidth and a second frequency hopping in the second bandwidth, and a period of the first frequency hopping is longer than a period of the second frequency hopping, The terminal according to Claim 1.

8. The reference signal is transmitted using a first frequency hopping in the first bandwidth and a second frequency hopping in the second bandwidth, The first frequency hopping is composed of the second frequency hopping and a frequency hopping related to the start position within the second bandwidth. The terminal according to claim 1.

9. The reference signal is transmitted using a first frequency hopping in the first bandwidth and a second frequency hopping in the second bandwidth. Within the period of the second frequency hopping, each hopping amount in the first frequency hopping is the same as each hopping amount in the second frequency hopping. The terminal according to claim 1.

10. Determine the sequence length of the reference signal based on the transmission Comb number. Transmit the reference signal generated with the sequence length. The bandwidth of the reference signal can be selected from a plurality of bandwidths including a first bandwidth and a second bandwidth, and a first lower limit value of the sequence length in the first bandwidth is the same as a second lower limit value of the sequence length in the second bandwidth. Communication method.

11. Control a process of determining the sequence length of the reference signal based on the transmission Comb number and a process of transmitting the reference signal generated with the sequence length. The bandwidth of the reference signal can be selected from a plurality of bandwidths including a first bandwidth and a second bandwidth, and a first lower limit value of the sequence length in the first bandwidth is the same as a second lower limit value of the sequence length in the second bandwidth. Integrated circuit.​

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