Base station, communication method, and integrated circuit

Abstract

To improve channel estimation accuracy using reference signals.SOLUTION: A terminal includes a control circuit that sets a first upper limit value of a frequency interval in which a first reference signal is arranged in a first bandwidth to be smaller than a second upper limit value of a frequency interval in which a second reference signal is arranged in a second bandwidth that is wider than the first bandwidth, and a transmission circuit that transmits the first reference signal based on the first upper limit value.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] In Release 17 (hereinafter referred to as "Rel. 17") of the 3rd Generation Partnership Project (3GPP), improvements to the coverage performance or capacity performance of the Sounding Reference Signal (SRS) were discussed in order to expand the functionality of Multiple-Input Multiple Output (MIMO) applied to New Radio access technology (NR) (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] RP-192436, “WID proposal for Rel.17 enhancements on MIMO for NR”, Samsung, December 2019 [Non-patent document 2] 3GPP TS 38.211 V16.1.0, "NR; Physical channels and modulation (Release 16)," 2020-03 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is room for further study on methods for improving the accuracy of channel estimation using reference signals.

[0005] Non-limiting examples of the present disclosure contribute to providing a terminal, a base station, and a communication method that improve the accuracy of channel estimation using a reference signal. [Means for solving the problem]

[0006] A terminal according to one embodiment of the present disclosure includes a control circuit that sets a first upper limit value of a frequency interval in which a first reference signal is allocated in a first bandwidth to be smaller than a second upper limit value of a frequency interval in which a second reference signal is allocated in a second bandwidth that is wider than the first bandwidth, and a transmission circuit that transmits the first reference signal based on the first upper limit value.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0008] According to an embodiment of the present disclosure, it is possible to improve the accuracy of channel estimation using a reference signal.

[0009] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0010] [Figure 1] Diagram showing an example of narrowband Sounding Reference Signal (SRS) transmission [Figure 2] FIG. 10 is a diagram showing an example of the relationship between the SRS transmission bandwidth, the number of transmission combs, and the length of the sequence for generating the SRS. [Figure 3] Block diagram showing an example of the configuration of a portion of a base station [Figure 4] Block diagram showing an example of the configuration of a part of a terminal [Figure 5] Block diagram showing an example of the configuration of a base station [Figure 6] Block diagram showing an example of a terminal configuration [Figure 7] A sequence diagram showing an example of the operation of a base station and a terminal. [Figure 8] FIG. 10 is a diagram showing an example of the relationship between the SRS transmission bandwidth and the number of transmission Combs according to the first embodiment. [Figure 9] FIG. 10 is a diagram showing an example of the relationship between the SRS transmission bandwidth, the number of transmission Combs, and the length of a sequence for generating an SRS according to the first embodiment; [Figure 10] FIG. 10 is a diagram showing another example of the relationship between the SRS transmission bandwidth and the number of transmission Combs according to the first embodiment. [Figure 11] FIG. 10 is a diagram showing another example of the relationship between the SRS transmission bandwidth, the number of transmission Combs, and the length of a sequence for generating an SRS according to the first embodiment. [Figure 12] A diagram showing an example of frequency hopping of SRS [Figure 13] FIG. 10 is a diagram showing an example of frequency hopping of SRS according to the second embodiment. [Figure 14] FIG. 10 is a diagram showing an example of frequency hopping of SRS according to the second embodiment. [Figure 15] FIG. 10 is a diagram showing an example of frequency hopping of SRS according to the second embodiment. [Figure 16] Diagram of an example architecture of a 3GPP NR system [Figure 17] Schematic diagram showing the functional separation between NG-RAN (Next Generation - Radio Access Network) and 5GC (5th Generation Core) [Figure 18] Sequence diagram of the Radio Resource Control (RRC) connection setup / reconfiguration procedure [Figure 19] Schematic diagram showing usage scenarios for enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC). [Figure 20] Block diagram illustrating an exemplary 5G system architecture for a non-roaming scenario DETAILED DESCRIPTION OF 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 (e.g., referred to as "NR SRS"), for example, a base station (e.g., also referred to as "eNB" or "gNB") may notify (or configure) information regarding the configuration of the SRS (hereinafter referred to as "SRS configuration information") to a terminal (e.g., also referred to as "User Equipment (UE)"). The SRS configuration information may define an "SRS resource set," which is a set of parameters used for each SRS resource, such as the SRS transmission timing, the SRS transmission frequency band, the sequence number for reference signal generation, the number of transmission combs (or the transmission subcarrier spacing), and the amount of cyclic shift. The SRS configuration information may be configured by higher layer signaling, such as a Radio Resource Control (RRC) layer. The SRS configuration information may also be referred to as "SRS-Config," which is configured in the RRC layer.

[0013] Examples of transmission methods for NR SRS in a frequency band include a "wideband SRS transmission method" and a "narrowband SRS transmission method." The wideband may be, for example, a band corresponding to a frequency band in which SRS can be transmitted (e.g., referred to as a "sounding band (sounding bandwidth)" or a "channel estimation-enabled frequency band"). The narrowband may be, for example, a band narrower than the sounding band (or wideband). In the wideband SRS transmission method, for example, an SRS may be transmitted in a transmission bandwidth corresponding to a bandwidth part (BWP), and wideband channel estimation may be performed all at once. In the narrowband SRS transmission method, for example, an SRS may be transmitted in a narrowband while changing the transmission band over time (in other words, by frequency hopping), and wideband channel estimation may be performed using the narrowband SRS multiple times.

[0014] For example, a terminal located near a cell boundary may experience a larger path loss than a terminal located near the center of the cell. Furthermore, there is an upper limit to the maximum transmission power of a terminal. Therefore, for example, when a terminal located near a cell boundary transmits an SRS in a wideband, the received power per unit frequency at the base station is likely to be low. Therefore, when a terminal located near a cell boundary transmits an SRS in a wideband, for example, the reception quality (e.g., Signal to Interference and Noise Ratio (SINR)) may be reduced, and the channel estimation accuracy may be degraded. Therefore, for example, a narrowband SRS transmission method may be applied to terminals located near a cell boundary, in which transmission power is allocated to a narrowband frequency band that is narrower than the wideband (in other words, transmission power density is increased).

[0015] On the other hand, for example, a terminal near the center of a cell may experience smaller path loss than a terminal near a cell boundary. Therefore, even if a terminal near the center of a cell transmits SRS in a wideband, the base station can ensure the received power per unit frequency for channel estimation, so a wideband SRS transmission method may be applied.

[0016] Furthermore, for example, in NR SRS, the sounding band may be set to be the same between terminals regardless of whether the SRS is a wideband SRS or a narrowband SRS. 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 a narrowband SRS, applying frequency hopping N times enables estimation of the channel quality of the same frequency band as the wideband SRS.

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

[0018] FIG. 1 is a diagram illustrating an example of narrowband SRS transmission 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 (for example, a narrowband SRS) with a transmission bandwidth of 4 RBs.

[0020] 3GPP Rel.17, for example, envisions a method of increasing the transmission power density of SRS when transmitting narrowband SRS. Increasing the transmission power density of SRS can improve the channel estimation accuracy for terminals with large path loss, such as terminals located near cell boundaries, and can improve SRS coverage performance.

[0021] Methods for increasing the transmission power density of SRS include, for example, narrowing the transmission bandwidth of SRS or increasing the number of transmission combs (in other words, widening the transmission subcarrier spacing).Furthermore, for example, frequency hopping may be applied to narrowband SRS transmission, and channel estimation over a wide band may be performed.

[0022] However, the narrower the SRS transmission bandwidth or the more transmission combs, the shorter the sequence length of the SRS generation sequence may become. For example, the shorter the sequence length of the SRS generation sequence, the greater the cross-correlation (or interference) between SRSs using different sequences, which may result in a deterioration in channel estimation accuracy.

[0023] Furthermore, the shorter the sequence length of the SRS generation sequence, the fewer the number of sequences with good Peak to Average Power Ratio (PAPR) characteristics or cross-correlation characteristics (e.g., Constant Amplitude Zero Auto Correlation (CAZAC) characteristics). For example, in NR, 30 sequences can be used as SRS generation sequences in each transmission bandwidth, and adjacent cells can reduce interference between them by transmitting SRSs generated from different sequences. For example, the shorter the sequence length of the SRS generation sequence, the greater the cross-correlation (or interference), which can degrade channel estimation accuracy.

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

number

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

[0026] In NR, for example, N sc RB = 12 (fixed value). In this case, for example, the SRS transmission bandwidth (m SRS,b ) and the number of transmitted combs (K TC ) and the sequence length (M sc,bSRS ) has the relationship shown in Figure 2. For example, as shown in Figure 2, when the SRS transmission bandwidth is 2 RBs or less, the sequence length may become equal to or less than a certain threshold (e.g., 3 [sc]) depending on the number of transmission combs. For example, when the sequence length becomes equal to or less than a certain threshold (e.g., 3 [sc]), cross-correlation (interference) between SRSs increases, which may result in a deterioration in the accuracy of channel estimation by SRSs.

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

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

[0029] For example, base station 100 may be an NR base station, and terminal 200 may be an NR terminal. Base station 100 may, for example, configure SRS configuration information related to SRS transmission for terminal 200, and receive SRS from terminal 200. Furthermore, terminal 200 may transmit SRS with a certain bandwidth and transmission Comb number in a specified (or configured) transmission band based on the SRS configuration information from base station 100, for example.

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

[0031] 4 is a block diagram showing a configuration example of a portion of terminal 200 according to an embodiment of the present disclosure. In terminal 200 shown in FIG. 4, control unit 203 (e.g., corresponding to a control circuit) sets a first upper limit value of a frequency interval (e.g., a transmission Comb number) in which a first reference signal (e.g., an SRS) is allocated in a first bandwidth to be lower than a second upper limit value of a frequency interval in which a second reference signal (e.g., an SRS) is allocated in a second bandwidth wider than the first bandwidth. Transmitter 206 (e.g., corresponding to a transmission circuit) transmits the first reference signal based on the first upper limit value.

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

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

[0034] The SRS resource set of the SRS configuration information may include parameters such as the transmission frequency band of each SRS resource (e.g., including 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 generating the reference signal, the cyclic shift amount (e.g., the cyclic shift value), or the sequence hopping.

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

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

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

[0038] The coding and modulation unit 102 may, for example, code and modulate the SRS setting information input from the control unit 101 and output the resulting modulated signal to the transmission processing unit 103 .

[0039] The transmission processing unit 103 may form a transmission signal by, for example, mapping the modulated signal input from the coding and modulation unit 102 to a frequency band in accordance with allocation information of radio resources for downlink data transmission input from the control unit 101. For example, if the transmission signal is an Orthogonal Frequency Division Multiplexing (OFDM) signal, the transmission processing unit 103 may form an OFDM signal by mapping the modulated signal to a frequency resource, performing an Inverse Fast Fourier Transform (IFFT) process to convert it into a time waveform, and adding a CP (Cyclic Prefix).

[0040] The transmitting unit 104 may, for example, 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 transmission radio processing via an antenna.

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

[0042] The reception processing unit 106 may, for example, identify resources to which the SRS is mapped based on the SRS configuration information input from the control unit 101, and extract signal components mapped to the identified resources from the received signal. For example, in the case of aperiodic SRS transmission, the reception processing unit 106 may receive the SRS in slots obtained by adding a slot offset set in the SRS resource set(s) to the transmission timing of the DCI. Furthermore, for example, in the case of semi-persistent SRS transmission or periodic SRS transmission, the reception processing unit 106 may periodically receive the SRS in slots identified by the transmission period and slot offset set in the SRS resource set. Furthermore, the reception processing unit 106 may, for example, identify frequency resources for the SRS from information on the transmission frequency band of the SRS resource included in the SRS configuration information.

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

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

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

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

[0047] Reception processing unit 202 may, for example, extract SRS setting information included in the received signal input from reception unit 201, and output the SRS setting information to control unit 203. Note that if the received signal is an OFDM signal, reception processing unit 202 may, for example, perform CP removal processing and Fourier transform (FFT) processing.

[0048] The control unit 203 may control the transmission of the SRS based on, for example, 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 identifies an SRS resource set to be used for transmitting the SRS based on the SRS setting information. Then, for example, the control unit 203 may extract SRS resource information (including, for example, a transmission bandwidth, a transmission comb number, and a frequency hopping pattern) to be applied to the SRS based on the identified SRS resource set, and output (or instruct or set) the SRS resource information to the reference signal generation unit 204 and the transmission processing unit 205. Note that in the case of aperiodic SRS transmission, the control unit 203 may detect the SRS transmission timing based on, for example, the SRS setting information and DCI (for example, trigger information).

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

[0050] For example, transmission processing unit 205 may map the SRS input from reference signal generating unit 204 to a frequency resource instructed by control unit 203. This forms a transmission signal. Note that if the transmission signal is an OFDM signal, transmission processing unit 205 may perform IFFT processing on the signal after mapping to the frequency resource and add a CP.

[0051] The transmitting unit 206 may perform radio transmission 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 radio transmission processing via an antenna.

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

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

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

[0055] Base station 100 may transmit (or configure or notify) SRS configuration information to terminal 200 by, for example, higher layer signaling (for example, an RRC layer signal) (S102). Note that, in the case of aperiodic SRS transmission, for example, base station 100 may transmit trigger information to terminal 200 by DCI (not shown).

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

[0057] [How to set the 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 base station 100 (for example, control unit 101) will be described.

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

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

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

[0061] 8, for example, an SRS with an SRS transmission bandwidth of less than 4 RBs may have a lower upper limit set (in other words, limited) on the number of available transmission Combs than an SRS with an SRS transmission bandwidth of 4 RBs or more. For example, the upper limit on the number of available transmission Combs for an SRS with an SRS transmission bandwidth of less than 4 RBs may be set according to the SRS transmission bandwidth.

[0062] For example, in Fig. 8, when the SRS transmission bandwidth is 2 RBs, the number of transmission combs available is either 2 or 4 (e.g., upper limit of the number of transmission combs: 4). Also, for example, in Fig. 8, when the SRS transmission bandwidth is 1 RB, the number of transmission combs available is 2 (e.g., upper limit of the number of transmission combs: 2). For example, as in Fig. 8, the narrower the SRS transmission bandwidth, the smaller the upper limit of the number of available transmission combs may be.

[0063] For example, as shown in FIG. 2 or equation (1), the greater the number of transmission Combs in an SRS for each SRS transmission bandwidth, the shorter the sequence length of the SRS generation sequence. Therefore, as shown in FIG. 8, for example, the narrower the SRS transmission bandwidth, the smaller the upper limit of the number of available transmission Combs is set, thereby preventing a decrease in the lower limit of the sequence length of the SRS generation sequence. Therefore, for example, even if the SRS transmission bandwidth is less than a threshold, the sequence length can be prevented from becoming shorter than a certain threshold. In other words, even if the SRS transmission bandwidth is less than a threshold, the lower limit of the sequence length can be maintained at or above a certain threshold.

[0064] Figure 9 is a diagram showing an example of the relationship between the SRS transmission bandwidth, the number of transmission combs, and the sequence length. In Figure 9, as an example, the SRS transmission bandwidth and the number of transmission combs may have the same relationship as that shown in Figure 8. As shown in Figure 9, the lower limit of the SRS generation sequence length corresponding to an SRS whose SRS transmission bandwidth, such as 2 RBs or 1 RB, is less than a threshold (e.g., 4 RBs) is 6 [sc]. In other words, in Figure 9, even an SRS whose SRS transmission bandwidth, such as 2 RBs or 1 RB, is less than a threshold (e.g., 4 RBs) can maintain the same lower limit of the SRS generation sequence length (e.g., 6 [sc]) as an SRS whose SRS transmission bandwidth, such as 4 RBs, is equal to or greater than the threshold.

[0065] This makes it possible to suppress, for example, an increase in cross-correlation (or interference) between SRSs due to the sequence length of the SRS generation sequence (in other words, the number of sequences that can be generated), and to suppress deterioration in channel estimation accuracy for SRSs. In other words, for example, by maintaining the lower limit of the sequence length at or above a certain threshold, it becomes possible to generate more sequences with good PAPR characteristics or cross-correlation characteristics. Thus, according to the present embodiment, for example, by increasing the number of transmission combs for SRSs, it is possible to suppress a decrease in channel estimation accuracy using SRSs and increase the transmission power density of SRSs, thereby improving SRS coverage performance.

[0066] Note that in this embodiment, an example in which the lower limit of the SRS generation sequence length is set to 6 [sc] has been described in FIGS. 8 and 9, but the lower limit of the sequence length is not limited to 6 [sc]. For example, the upper limit of the number of transmission Combs is not limited to the value shown in FIG. 8 or 9. FIGS. 10 and 11 are diagrams illustrating other examples of the relationship between the SRS transmission bandwidth, the number of transmission Combs, 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 of the number of available transmission Combs may be set smaller than in FIG. 8. As a result, for example, as shown in FIG. 11, the lower limit of the SRS generation sequence length is set to (or maintained at) 12 [sc], which is larger than in FIG. 9. As a result, in FIGS. 10 and 11, it becomes easier to use SRSs with longer sequence lengths than in FIGS. 8 and 9, for example, thereby improving the accuracy of channel estimation using SRS.

[0067] In this embodiment, in FIGS. 8 to 10, the number of subcarriers per RB in equation (1) is 12 (N sc RB = 12) has been described as an example, but the number of subcarriers per RB is not limited to 12 [sc / RB]. For example, if the number of subcarriers per RB is 6 [sc / RB], the sequence length will be half of the sequence lengths shown in Figures 9 and 11, and the upper limit of the number of available transmission combs will be halved compared to Figures 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 (for example, 4 RBs) will be described.

[0069] [Frequency hopping for narrowband SRS] As described above, for example, the minimum transmission bandwidth of an NR SRS is 4 RBs, and the transmission bandwidth of the SRS may be a multiple of 4. Furthermore, by frequency hopping the narrowband SRS N times (N is an integer), 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 be assumed. In this case, for example, if a frequency hopping pattern with a granularity of 2 RBs or 1 RB is applied, collision of the 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 2 RB granularity (in other words, in units of 2 RBs) is set for the SRS transmitted by UE#0, and a frequency hopping pattern with 4 RB granularity (in other words, in units of 4 RBs) is set for the SRS transmitted by UE#1. In Fig. 12, for example, collision of the SRS transmitted from UE#0 and UE#1 may occur at least part of the SRS transmission timings of UE#0 and UE#1.

[0072] Collision of SRSs may cause interference between SRSs, which may degrade the accuracy of channel estimation by SRSs.

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

[0074] In the configuration example of the base station and terminal according to this embodiment, for example, some functions may be different from those in the first embodiment, and other functions may be the same as those in the first embodiment.

[0075] [Base station configuration] In base station 100 according to this embodiment, control unit 101 may set, for example, a frequency hopping pattern for SRS to be allocated in each transmission bandwidth. For example, control unit 101 may set a frequency hopping pattern that prevents frequency resource collision between a frequency hopping pattern to be applied to an SRS whose transmission bandwidth is less than a threshold (for example, narrowband SRS) and a frequency hopping pattern to be applied to an SRS whose transmission bandwidth is equal to or greater than the threshold (for example, narrowband SRS). Control unit 101 may output SRS setting information including the set frequency hopping pattern to coding / modulation unit 102 and reception processing unit 106.

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

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

[0078] [Device configuration] Terminal 200 according to this embodiment may map an SRS to a resource instructed to transmit the SRS, based on, for example, SRS setting information (including, for example, a frequency hopping pattern) from base station 100, and transmit the SRS.

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

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

[0081] For example, base station 100 and terminal 200 may control frequency hopping of SRS with a transmission bandwidth less than the threshold in units of transmission bands (for example, 4 RBs) in which SRS with the threshold transmission bandwidth is allocated per slot.

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

[0083] <Example 1> 13 and 14 are diagrams showing examples of setting frequency hopping patterns for narrowband SRS.

[0084] In Figures 13 and 14, base station 100 and terminal 200 may control the frequency hopping (e.g., frequency hopping between slots) of narrowband SRS (e.g., SRS of UE#0) whose transmission bandwidth is less than a threshold (e.g., 4 RBs) in transmission bandwidth units (e.g., 4 RB units) of SRS placed in a transmission bandwidth corresponding to the threshold.

[0085] Also, in Figures 13 and 14, base station 100 and terminal 200 may control frequency hopping between multiple SRS symbols in which SRS is placed within a slot, for example, in a frequency hopping pattern of narrowband SRS (for example, a frequency hopping pattern set for UE #0) whose transmission bandwidth is less than a threshold (for example, 4 RB).

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

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

[0088] 13 and 14, the 4-RB band in which frequency hopping within a slot is performed (in other words, the hopping unit of frequency hopping between slots) may be, for example, one of the bands determined based on the frequency hopping pattern of the NR SRS (or the SRS whose transmission bandwidth corresponds to a threshold). For example, as shown in FIGS. 13 and 14, the total transmission bandwidth (e.g., 4 RBs) in which each of the multiple SRSs that frequency hop between symbols within a slot in UE#0 are allocated is the same as the transmission bandwidth (e.g., 4 RBs) of the SRSs allocated 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 allocated may be different from the transmission band in which the SRS of UE#1 is allocated.

[0089] By setting this frequency hopping pattern, for example, a frequency hopping pattern of a narrowband SRS whose transmission bandwidth is less than a threshold (e.g., 4 RBs) and a frequency hopping pattern of a narrowband SRS whose transmission bandwidth is equal to or greater than a threshold (e.g., 4 RBs) are orthogonally multiplexed in the frequency domain. Therefore, even when frequency hopping patterns of different granularities are applied to different terminals 200, it is possible to suppress collisions of SRS.

[0090] Furthermore, for example, for a narrowband SRS whose transmission bandwidth is less than a threshold (for example, 4RB), frequency hopping is applied between symbols within a slot, so the hopping period (or frequency hopping cycle) can be reduced. For example, in Figures 13 and 14, the hopping period for an SRS whose transmission bandwidth is less than the threshold is 4 slots.

[0091] In Figures 13 and 14, as an example, we have explained a case where, in frequency hopping between symbols within a slot, a pattern is set in which the later the SRS symbol in the time domain, the higher the band in the frequency domain it is placed in; however, 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 a frequency hopping pattern for a narrowband SRS.

[0093] In Figure 15, base station 100 and terminal 200 control the frequency hopping of narrowband SRS (e.g., SRS for UE #0) whose transmission bandwidth is less than a threshold (e.g., 4 RBs) for each frequency hopping period (e.g., each slot) of SRS whose transmission bandwidth corresponds to a threshold (e.g., 4 RBs).Furthermore, as shown in Figure 15, in the frequency hopping pattern (e.g., frequency hopping pattern for UE #0) of narrowband SRS whose transmission bandwidth is less than a threshold (e.g., 4 RBs), the SRS may be frequency hopped in transmission bandwidth units (e.g., 4 RB units) of SRS (e.g., SRS for UE #1) whose transmission bandwidth corresponds to the threshold.

[0094] For example, in Fig. 15, a frequency hopping pattern with 2RB granularity (in other words, a transmission bandwidth less than a threshold) is set for the SRS transmitted by UE#0, and a frequency hopping pattern with 4RB granularity (in other words, a transmission bandwidth equal to or greater than a threshold) is set for the SRS transmitted by UE#1. In Fig. 15, for example, a narrowband SRS of 2RBs may be placed in one symbol within a slot and frequency hopped between slots in 4RB units (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 a 2-RB narrowband SRS is 8 slots.

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

[0097] 15, the 4-RB band in which frequency hopping of an SRS whose transmission bandwidth is less than the threshold (in other words, the hopping unit of frequency hopping between slots) is performed may be, for example, 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 FIG. 15, in each slot, the transmission band in which the SRS of UE#0 is allocated may be different from the transmission band in which the SRS of UE#1 is allocated.

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

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

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

[0101] On the other hand, in Example 2, compared to Example 1, it is possible to reduce the amount of SRS resources allocated in each slot.

[0102] An example of setting a frequency hopping pattern for narrowband SRS has been described above.

[0103] In this embodiment, in a frequency hopping pattern of a narrowband SRS whose transmission bandwidth is less than a threshold (e.g., 4 RBs), the SRS is transmitted in at least a part of the transmission band set by the frequency hopping pattern of an SRS whose transmission bandwidth corresponds to the threshold (e.g., 4 RBs). In other words, the frequency hopping pattern of a narrowband SRS whose transmission bandwidth is less than the threshold may reuse the setting (in other words, the mechanism, for example, the hopping unit) of the frequency hopping pattern of an SRS whose transmission bandwidth corresponds to the threshold.

[0104] As a result, in this embodiment, SRSs can be orthogonally multiplexed in the frequency domain in a frequency hopping pattern of narrowband SRSs whose transmission bandwidth is less than a threshold and a frequency hopping pattern of narrowband SRSs whose transmission bandwidth is equal to or greater than the threshold, thereby preventing collisions between SRSs. Therefore, according to this embodiment, interference between SRSs can be prevented, and the accuracy of channel estimation by SRSs can be improved.

[0105] An embodiment of the present disclosure has been described above.

[0106] In one embodiment of the present disclosure, a case has been described in which the SRS configuration information is configured in the terminal 200 by higher layer signaling (e.g., RRC layer signaling), but the configuration of the SRS configuration information is not limited to higher layer signaling and may be other signaling (e.g., physical layer signaling).

[0107] Furthermore, in an 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 a reference signal such as an SRS, and may be other signals (or information). For example, an embodiment of the present disclosure may be applied to a response signal to data (e.g., also referred to as an ACK / NACK or HARQ-ACK) instead of an SRS.

[0108] Furthermore, in one embodiment of the present disclosure, parameters such as SRS resource candidates (e.g., a combination of transmission bandwidth, number of transmission combs, and sequence length), threshold (e.g., 4 RBs), upper limit of number of transmission combs, frequency hopping granularity (e.g., 1 RB, 2 RBs, or 4 RBs), and number of subcarriers per RB are not limited to the above examples and may be other values.

[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 a Physical Downlink Control Channel (PDCCH) of the physical layer, or a signal (or information) transmitted in a Medium Access Control (MAC) or Radio Resource Control (RRC) of a higher layer. Furthermore, the signal (or information) is not limited to being notified by a downlink control signal, but may be predefined in a specification (or standard) or may be preconfigured in a base station and a 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 a PDCCH of the physical layer, or a signal (or information) transmitted in a MAC or RRC of a higher layer. Furthermore, the signal (or information) is not limited to being notified by an uplink control signal, but may be predefined in a specification (or standard), or may be preconfigured in a base station and a terminal. Furthermore, the uplink control signal may be replaced with, for example, uplink control information (UCI), 1st stage sidelink control information (SCI), or 2nd stage SCI.

[0111] (base station) In an 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, etc. In addition, in sidelink communication, a terminal may be used instead of the base station. In addition, a relay device that relays communication between an upper node and a terminal may be used instead of the base station.

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

[0113] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

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

[0115] (reference signal) In one embodiment of the present disclosure, the reference signal is a signal known by both the base station and the mobile station, and may 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 an embodiment of the present disclosure, the unit of time resource is not limited to one or a combination of slots and symbols, but may be, for example, 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, or a Single Carrier-Frequency Division Multiplexing (SC-FDMA) symbol, or another time resource unit. Furthermore, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be another number of symbols.

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

[0118] (communication) An 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 an embodiment of the present disclosure may be replaced with any of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0119] An embodiment of the present disclosure may be applied to a terrestrial network, a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS), or a terrestrial network in which transmission delay is large compared to the symbol length or slot length, such as a network with a large cell size or an ultra-wideband transmission network.

[0120] (antenna port) In one embodiment of the present disclosure, an antenna port refers to a logical antenna (antenna group) consisting of one or more physical antennas. For example, an antenna port does not necessarily refer to a single physical antenna, but may refer to an array antenna consisting of multiple antennas. For example, the number of physical antennas that an antenna port is composed of is not specified, and the antenna port may be specified as the smallest unit by which a terminal station can transmit a reference signal. Furthermore, an antenna port may also be specified as the smallest unit for multiplying a weighting factor of a precoding vector.

[0121] <5G NR system architecture and protocol stack> 3GPP is working on the next release of fifth-generation cellular technology (also known 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, allowing for the prototyping and commercial deployment of 5G NR compliant devices (e.g., smartphones).

[0122] For example, the system architecture assumes a Next Generation - Radio Access Network (NG-RAN) with gNBs. The gNBs provide UE-side termination of NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity that performs AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity that performs UPF) via an 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 NR user plane protocol stack (see, for example, 3GPP TS 38.300, section 4.4.1) includes the Packet Data Convergence Protocol (PDCP) sublayer (see, for example, TS 38.300, section 6.4), the Radio Link Control (RLC) sublayer (see, for example, TS 38.300, section 6.3), and the Medium Access Control (MAC) sublayer (see, for example, TS 38.300, section 6.2), which are terminated on the network side at the gNB. A new Access Stratum (AS) sublayer (Service Data Adaptation Protocol (SDAP)) has also been introduced on top of PDCP (see, for example, 3GPP TS 38.300, section 6.5). A control plane protocol stack has also been defined for NR (see, for example, TS 38.300, section 4.4.2). An overview of Layer 2 functions is given in Section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in clauses 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in clause 7 of TS 38.300.

[0124] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling-related functions, including handling various numerologies.

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

[0126] NR use cases / deployment scenarios may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (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 approximately three times higher than those offered by IMT-Advanced. Meanwhile, URLLC imposes stricter requirements for ultra-low latency (0.5 ms user-plane latency for both UL and DL) and high reliability (1-10-5 within 1 ms). Finally, mMTC may require preferably high connection density (1,000,000 devices / km2 in urban environments), wide coverage in adverse environments, and extremely long battery life (15 years) for low-cost devices.

[0127] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be valid for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with small delay spreads. Subcarrier spacing may be optimized accordingly to maintain similar CP overhead. NR may support one or more subcarrier spacing values. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently considered. The symbol length Tu and subcarrier spacing Δf are directly related by the equation Δf = 1 / Tu. Similar to LTE systems, the term "resource element" can be used to mean the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0128] In the new radio system 5G-NR, a resource grid of subcarriers and OFDM symbols is defined for each numerology and each carrier in the uplink and downlink. Each element of the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a 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 node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0130] For example, the gNB and ng-eNB host the following main functions: - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, encryption, and integrity protection of data; - AMF selection at UE attach time if routing to the AMF cannot be determined from the information provided by the UE; - Routing of user plane data towards UPF; - Routing of control plane information towards AMF; - Setting up and tearing down connections; - scheduling and sending of paging messages; - Scheduling and transmission of system broadcast information (originating from AMF or Operation, Admission, Maintenance (OAM) Function); - Configuring measurements and measurement reporting for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; - Network slicing support; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - NAS message delivery function; - Sharing of radio access networks; - Dual connectivity; - Close cooperation between NR and E-UTRA.

[0131] The Access and Mobility Management Function (AMF) hosts the following main functions: - Ability to terminate Non-Access Stratum (NAS) signaling; - NAS signaling security; - Access Stratum (AS) security control; - 3GPP Core Network (CN) inter-node signaling for mobility between access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Managing the registration area; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization, including checking roaming privileges; - Mobility management control (subscription and policy); - Network slicing support; - Selection of Session Management Function (SMF).

[0132] Additionally, the User Plane Function (UPF) hosts the following main functions: - Anchor points for intra-RAT / inter-RAT mobility (if applicable); - External PDU (Protocol Data Unit) session points for interconnection with data networks; - Packet routing and forwarding; - Packet inspection and policy rule enforcement for the user plane part; - Traffic usage reporting; - uplink classifier to support routing of traffic flows to the data network; - 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 for QoS flows of SDFs); - 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 UPF; - Traffic steering setting function in the User Plane Function (UPF) for routing traffic to appropriate destinations; - Enforcement of control plane 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 transitions from RRC_IDLE to RRC_CONNECTED (see TS 38.300 v15.6.0).

[0135] RRC is a higher layer signaling protocol used to configure the UE and the gNB. With this transition, the AMF prepares UE context data (including, for example, PDU session context, security keys, UE radio capabilities, and UE security capabilities) and sends it to the gNB with an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding with a SecurityModeComplete message. The gNB then sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB reconfigures the UE to set up a Signaling Radio Bearer 2 (SRB2) and a Data Radio Bearer (DRB). For signaling-only connections, the RRCReconfiguration steps are omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0136] Therefore, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) that includes: control circuitry that, in operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, in operation, transmits an initial context setup message to the gNodeB via the NG connection 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 that includes a resource allocation configuration information element (IE) to the UE via the signaling radio bearer. Then, the UE performs uplink transmission or downlink reception based on the resource allocation configuration.

[0137] <IMT usage scenarios from 2020 onwards> Figure 19 shows some use cases for 5G NR. The 3rd Generation Partnership Project New Radio (3GPP NR) is considering three use cases envisioned by IMT-2020 to support a wide variety of services and applications. The first phase of specifications for enhanced mobile broadband (eMBB) has been completed. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to expanding support for eMBB. Figure 19 shows some example use scenarios envisioned for IMT beyond 2020 (see, for example, ITU-R M.2083 Figure 2).

[0138] URLLC use cases have stringent performance requirements, such as throughput, latency, and availability. URLLC use cases are envisioned as one of the enabling technologies for future applications, such as wireless control of industrial production or manufacturing processes, remote medical surgery, automated power transmission and distribution in smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by TR 38.913. Key requirements for NR URLLC in Release 15 include a target user plane latency of 0.5 ms on the uplink (UL) and 0.5 ms on the downlink (DL). The overall URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size at a user plane latency of 1 ms.

[0139] From a physical layer perspective, reliability can be improved in many possible ways. Current reliability improvement room includes defining a separate CQI table for URLLC, more compact DCI formats, PDCCH repetition, etc. However, this room can be expanded to achieve ultra-high reliability as NR (with respect to the key requirements of NR URLLC) becomes more stable and developed. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0140] Additionally, technology enhancements targeted by NR URLLC aim to improve latency and reliability. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition in the data channel, and preemption in the downlink. Preemption means that a transmission with previously allocated resources is stopped and the allocated resources are used for another transmission with a later requested lower latency / higher priority requirement. Thus, a previously allowed transmission is preempted by a later transmission. Preemption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0141] The use case for massive machine-type communication (mMTC) is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to latency. These devices are required to be low cost and have very long battery life. From an NR perspective, using very narrow bandwidth portions is one solution that saves power and allows for long battery life from the UE perspective.

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

[0143] For NR URLLC, further use cases with more stringent requirements are envisioned, such as factory automation, transportation, and power distribution: high reliability (up to 10-6 level), high availability, packet sizes up to 256 bytes, and time synchronization down to a few μs (depending on the use case, the value can be 1 μs or a few μs depending on the frequency range and low latency in the 0.5 ms to 1 ms range (e.g., 0.5 ms latency on the targeted user plane)).

[0144] Furthermore, for NR URLLC, several technical enhancements may be available from the perspective of the physical layer. These technical enhancements include the enhancement of the Physical Downlink Control Channel (PDCCH) related to compact DCI, the repetition of PDCCH, and the increase in PDCCH monitoring. 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 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 Quality of Service (QoS) 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 granularity 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, the NG-RAN establishes at least one Data Radio Bearer (DRB) for each PDU session, e.g., as shown above with reference to Figure 18. Additional DRBs for the QoS flows of that PDU session can be configured later (when this is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and the 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and the NG-RAN associate UL and DL QoS flows with DRBs.

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

[0148] Figure 20 further illustrates further functional units of the 5G architecture, namely, 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-provided services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and run in a cloud computing environment.

[0149] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitter that, in operation, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of 5GC functions (e.g., an NEF, an AMF, an SMF, a PCF, an UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements; and a control circuit that, in operation, performs a service using the established PDU session.

[0150] The present disclosure can be realized by software, hardware, or software linked to hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

[0151] The integrated circuit method is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0152] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology is also a possibility.

[0153] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a wireless transceiver and processing / control circuitry. The wireless transceiver may include a receiver and a transmitter, or both functions. The wireless transceiver (transmitter and receiver) may include a radio frequency (RF) 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 (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0154] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (such as appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0155] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0156] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0157] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0158] A terminal according to one embodiment of the present disclosure includes a control circuit that sets a first upper limit value of a frequency interval in which a first reference signal is allocated in a first bandwidth to be smaller than a second upper limit value of a frequency interval in which a second reference signal is allocated in a second bandwidth that is 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 transmission bands in which the second reference signal is allocated for each unit time interval.

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

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

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

[0163] In one embodiment of the present disclosure, when the first bandwidth is two resource blocks, the first upper limit value is equal to or less than four subcarriers.

[0164] In one embodiment of the present disclosure, when the first bandwidth is one resource block, the first upper limit value is equal to or less than two subcarriers.

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

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

[0168] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2020-121431, filed on July 15, 2020, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0169] One embodiment of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0170] 100 base stations 101,203 Control unit 102 Encoding and modulation section 103,205 Transmission processing unit 104,206 Transmitter 105,201 Receiver 106,202 Receiving processing section 107 Reference signal receiver 200 devices 204 Reference signal generation section

Claims

1. a control circuit that determines a sequence length of a reference signal based on the number of transmission combs; a receiver for receiving 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; Base station.

2. a first upper limit value of the transmission Comb number in the first bandwidth is smaller than a second upper limit value of the transmission Comb number in the second bandwidth; The base station of claim 1 .

3. the first bandwidth is smaller than the second bandwidth; The base station of claim 1 .

4. The larger the transmission Comb number, the shorter the sequence length of the reference signal. The base station of claim 1 .

5. the first bandwidth is less than four resource blocks and the second bandwidth is equal to or greater than four resource blocks; The base station of claim 1 .

6. When the first bandwidth is four resource blocks and the second bandwidth is two resource blocks, a first upper limit value of the transmission Comb number in the first bandwidth is 8, and a second upper limit value of the transmission Comb number in the second bandwidth is 4. The base station of 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 base station of 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 comprises the second frequency hopping and a frequency hopping about a starting position within the second bandwidth; The base station of 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 second frequency hopping period, each hopping amount in the first frequency hopping is the same as each hopping amount in the second frequency hopping. The base station of claim 1 .

10. Determine the sequence length of the reference signal based on the number of transmission combs; receiving 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. A process of determining a sequence length of a reference signal based on the number of transmission combs; a process of receiving 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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