Receiving device, transmitting device, receiving method, and transmitting method

Abstract

In the present invention, a mobile station (200) is provided with: a control circuit that, on the basis of information that can specify the disposition of a first reference signal in a first system, determines the disposition of a second reference signal in a second system; and a receiving circuit that receives the second reference signal on the basis of the determined disposition. Figure 8

Description

Receiving device, transmitting device, receiving method, and transmitting method

[0001] The present disclosure relates to a receiving device, a transmitting device, a receiving method, and a transmitting method.

[0002] A communication system known as the fifth-generation mobile communication system (5G) is currently under consideration. The 3rd Generation Partnership Project (3GPP), an international standardization organization, is studying the advancement of the 5G communication system from the perspectives of both the advancement of the LTE / LTE-Advanced system and New Radio Access Technology (also referred to as New RAT or NR), a new method that is not necessarily backward compatible with the LTE / LTE-Advanced system (see, for example, Non-Patent Document 1).

[0003] In NR, technologies (e.g., DSS: Dynamic Spectrum Sharing) that allow NR systems and LTE systems to coexist and communicate simultaneously in the same frequency band are being considered (see, for example, Non-Patent Document 2).

[0004] RP-181726, "Revised WID on New Radio Access Technology", NTT DOCOMO, September 2018RP-191042, "Enhancements for dynamic spectrum sharing in Rel-16", Ericsson, June 2019RP-191599, "Enhancements for dynamic spectrum sharing in Rel-16", Ericsson, June 20193GPP TS 38.211 V15.6.0, "NR; Physical channels and modulation (Release 15)," 2019-063GPP TS 38.331 V15.6.0, "NR; Radio Resource Control (RRC) protocol specification (Release 15)," 2019-063GPP TS 38.214 V15.6.0, "NR; Physical layer procedures for data (Release 15)," 2019-06

[0005] However, the method of allocating reference signals has not been fully studied.

[0006] Non-limiting examples of the present disclosure contribute to providing a receiving device, a transmitting device, a receiving method, and a transmitting method that can appropriately allocate reference signals.

[0007] A receiving device according to one embodiment of the present disclosure includes a control circuit that determines an arrangement of a second reference signal in a second system based on information that can identify an arrangement of a first reference signal in a first system, and a receiving circuit that receives the second reference signal based on the determined arrangement.

[0008] 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.

[0009] According to an embodiment of the present disclosure, reference signals can be appropriately arranged.

[0010] Further advantages and benefits of one embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some 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.

[0011] Diagram showing an example of DSSDiagram showing an example of PDSCH mapping type BBlock diagram showing an example of CRS arrangementDiagram showing an example of orthogonal DMRS based MU-MIMO and DSSBlock diagram showing an example of the configuration of a part of a base stationBlock diagram showing an example of the configuration of a part of a mobile stationBlock diagram showing an example of the configuration of a base stationBlock diagram showing an example of the configuration of a mobile stationFlowchart showing examples of operations of a base station and a mobile stationDiagram showing an example of signal arrangement according to operation example 1-1Diagram showing an example of signal arrangement according to operation example 1-2Diagram showing an example of signal arrangement according to operation example 1-3Diagram showing an example of signal arrangement according to operation example 1-4Diagram showing an example of signal arrangement according to operation example 1-4Diagram showing an example of operation when orthogonal DMRS based MU-MIMO is not operatedDiagram showing an example of signal arrangement according to operation example 2-1Diagram showing an example of signal arrangement according to operation example 2-2

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0013] [Dynamic Spectrum Sharing (DSS)] In DSS, an NR system and an LTE system can coexist and communicate simultaneously in the same frequency band.

[0014] For example, in the operation of DSS in Release 15 (hereinafter referred to as Rel-15), a channel for LTE may be allocated in an LTE downlink subframe within the LTE frequency band (or carrier). For example, as shown in Fig. 1, in an LTE downlink subframe, a control signal and a reference signal (e.g., a Cell-specific Reference Signal (CRS)) for LTE may be allocated in one or more symbols (e.g., Orthogonal Frequency Division Multiplexing (OFDM) symbols) from the beginning, and a downlink data channel for LTE (e.g., an LTE Physical Downlink Shared Channel (PDSCH)) and a CRS may be allocated in the remaining OFDM symbols.

[0015] In DSS, for example, during the period of an OFDM symbol in which an LTE PDSCH is allocated, as shown in FIG. 1, the LTE PDSCH may be allocated to some frequency bands, and an NR downlink control channel (NR PDCCH: Physical Downlink Control Channel) or a downlink data channel (NR PDSCH) may be allocated to other frequency bands. In other words, the LTE PDSCH and each NR channel may be frequency-divided. However, as shown in FIG. 1, the CRS (or sometimes referred to as the LTE CRS) may be transmitted not only in the frequency band in which the LTE PDSCH is allocated, but also in the frequency band in which each NR channel is allocated.

[0016] For example, with regard to DSS, the introduction of a PDSCH mapping method (e.g., referred to as NR PDSCH mapping Type B) with a length of 9 and 10 OFDM symbols has been proposed (see, for example, Non-Patent Document 3). For example, with this PDSCH mapping method, the position of an NR reference signal (e.g., a demodulation reference signal (DMRS)) can be defined or set at a symbol position that does not collide with a symbol containing an LTE CRS. The introduction of this NR PDSCH mapping Type B improves the operational efficiency of DSS.

[0017] However, such PDSCH mapping is not specified in Rel-15 (see, for example, Non-Patent Document 4), and the allocation of DMRS within this PDSCH has not been fully considered.

[0018] Therefore, in one embodiment of the present disclosure, a method for arranging DMRSs in a PDSCH will be described.

[0019] [DMRS mapping] As an example of a method for arranging DMRS in an uplink data channel (e.g., PUSCH: Physical Uplink Shared Channel), a method for arranging DMRS in NR PUSCH mapping Type B, which has a length of 9 and 10 OFDM symbols, is specified in Non-Patent Document 4 (e.g., Section 6.4.1.1.3).

[0020] For example, a similar arrangement method to the DMRS arrangement method in NR PUSCH mapping Type B can be applied to DMRS in NR PDSCH mapping Type B, which has a length of 9 and 10 OFDM symbols in a downlink data channel (e.g., PDSCH). For example, a DMRS arrangement method in NR PDSCH mapping Type B, which has a length of 9 and 10 OFDM symbols, can be as shown in FIG. 2. For example, "dmrs-AdditionalPosition" shown in FIG. 2 is a higher layer parameter (e.g., also referred to as a radio resource control (RRC) parameter) that indicates the position of the DMRS (in other words, the Additional DMRS). dmrs-AdditionalPosition is, for example, notified (in other words, configured) from a base station (e.g., also referred to as a gNB) to a mobile station (e.g., a terminal or UE: also referred to as User Equipment).

[0021] Hereinafter, the DMRS arrangement method shown in FIG. 2 will be referred to as “Assumption 1.” For example, in Assumption 1 shown in FIG. 2, ｄ At ≠9 or ≠10, ​​the first symbol (or start symbol) in which the PDSCH is scheduled in the slot is “l ０" and the symbol indicated by "dmrs-AdditionalPosition" (e.g., l ０ The DMRS can be placed at a position relative to the reference point (=0).

[0022] [NR DMRS shift] As described above, in DSS, for example, the NR PDSCH may be transmitted in the frequency band in which the LTE CRS is transmitted. In this case, the DMRS in the NR PDSCH and the LTE CRS may be designed not to collide in time and frequency resources (see, for example, Non-Patent Document 3).

[0023] For example, if there is a possibility of collision between the LTE CRS and a DMRS in an NR PDSCH configured based on "Assumption 1," the base station may transmit the DMRS at a location different from the location (in other words, resource location) of the DMRS configured based on "Assumption 1." Here, for example, the process of changing the location of the DMRS to a location different from the location configured based on "Assumption 1" may also be referred to as a "DMRS shift."

[0024] [CRS Mapping] The symbol where the CRS is allocated in an LTE subframe (i.e., its position in the time domain) varies depending on, for example, the number of CRS ports or the type of subframe. Subframe types include, for example, multimedia broadcast service single frequency network (MBSFN) subframes and non-MBSFN (non-MBSFN) subframes. Figure 3 shows an example of how the CRS is allocated. For example, in an MBSFN subframe with one or two CRS ports, the CRS is transmitted in four symbols, i.e., symbols 0, 4, 7, and 11. For example, in an MBSFN subframe with four CRS ports, the CRS is transmitted in six symbols, i.e., symbols 0, 1, 4, 7, 8, and 11. For example, in a non-MBSFN subframe, the CRS is transmitted in one symbol, i.e., symbol 0, or two symbols, i.e., symbols 0 and 1.

[0025] Here, the first symbol in a subframe or slot is referred to as the "0th symbol."

[0026] Furthermore, the location and number of ports of the CRS in the frequency domain, and the timing of the MBSFN subframe can be configured in the mobile station by, for example, higher layer parameters (for example, the RRC parameter "RateMatchPatternLTE-CRS").

[0027] [Multi-user Multiple Input Multiple Output (MU-MIMO)] In MU-MIMO for multiple mobile stations, there is an operation in which the NR DMRS ports between the mobile stations are orthogonal (for example, referred to as orthogonal DMRS-based MU-MIMO). In the case of orthogonal DMRS-based MU-MIMO, for example, as shown in FIG. 4, it is assumed that the NR DMRS ports between mobile station A and mobile station B are orthogonal.

[0028] For example, if DSS operation is performed for mobile station A but not for mobile station B, a case may occur (not shown) in which a DMRS shift is performed for mobile station A but not for mobile station B. In this case, the positions of the DMRSs of mobile station A and mobile station B are different, which may destroy the orthogonality between the DMRS ports.

[0029] In Rel-15, for example, a DCI related to antenna port mapping notifies a mobile station that "all the remaining orthogonal antenna ports are not associated with transmission of PDSCH to another UE," thereby implicitly notifying the mobile station that orthogonal DMRS based MU-MIMO will be operated (see, for example, Non-Patent Document 6).

[0030] (First Embodiment) [Outline of a Communication System] A communication system according to this embodiment includes a base station (corresponding to a transmitting device) 100 and a mobile station (corresponding to a receiving device) 200.

[0031] In this embodiment, for example, a method is described in which the base station 100 and the mobile station 200 determine whether or not to change (in other words, shift) the symbol in which the DMRS is allocated to a slot (e.g., called an NR slot) that transmits an NR signal (e.g., a PDSCH) in the downlink to a symbol different from the set symbol (e.g., a symbol based on Assumption 1).

[0032] This determination allows the base station 100 and the mobile station 200 to suppress collisions between DMRS and CRS, even when, for example, orthogonal DMRS-based MU-MIMO is operated for the mobile station 200. Furthermore, the base station 100 and the mobile station 200 can suppress a loss of orthogonality between DMRS ports of the mobile stations 200.

[0033] 5 is a block diagram showing a configuration example of a portion of a base station 100 according to this embodiment. In the base station 100 shown in FIG. 5, a control unit 101 (e.g., corresponding to a control circuit) determines the allocation of a second reference signal (e.g., DMRS) in a second system (e.g., NR system) based on information capable of identifying the allocation of a first reference signal (e.g., CRS) in a first system (e.g., LTE system). A transmission unit 104 (e.g., corresponding to a transmission circuit) transmits the second reference signal in the determined allocation.

[0034] Fig. 6 is a block diagram showing an example configuration of a portion of a mobile station 200 according to this embodiment. In the mobile station 200 shown in Fig. 6, a control unit 206 (e.g., corresponding to a control circuit) determines the allocation of a second reference signal (e.g., a DMRS) in a second system (e.g., an NR system) based on information capable of identifying the allocation of a first reference signal (e.g., a CRS) in a first system (e.g., an LTE system). A receiving unit 202 (e.g., corresponding to a receiving circuit) receives the second reference signal based on the determined allocation.

[0035] [Configuration of Base Station] Fig. 7 is a block diagram showing an example configuration of base station 100 according to this embodiment. In Fig. 7, base station 100 has control unit 101, coding / modulation unit 102, signal mapping unit 103, transmission unit 104, and antenna 105.

[0036] The control unit 101 generates, for example, an upper layer signal (e.g., RRC parameters) including parameters to be set in the mobile station 200, and outputs the signal to the coding and modulation unit 102. The upper layer signal may include, for example, information related to LTE CRS (e.g., RateMatchPatternLTE-CRS) or information related to a band to be set in the mobile station 200 (e.g., active BWP: Bandwidth part).

[0037] Furthermore, the control unit 101 determines information related to data (for example, PDSCH). For example, the control unit 101 determines an active BWP in which the PDSCH is transmitted, an allocation region of the PDSCH (for example, referred to as a PDSCH region), or whether orthogonal DMRS port based MU-MIMO is to be operated. Then, the control unit 101 outputs downlink control information (for example, DCI: Downlink Control Information) including information for explicitly or implicitly notifying the determined information to the signal mapping unit 103. Furthermore, the control unit 101 outputs (in other words, instructs) the determined PDSCH region to the signal mapping unit 103.

[0038] Furthermore, the control unit 101 determines whether to change (in other words, shift) the position of the DMRS in the PDSCH (e.g., the position of the symbol) from a reference position (e.g., a position associated with the PDSCH region, e.g., the position of Assumption 1 shown in FIG. 2 ). The control unit 101 outputs information related to the determined position of the DMRS to the signal mapping unit 103.

[0039] The coding and modulation section 102 performs error correction coding and modulation on the data (for example, PDSCH) and the upper layer signal input from the control section 101 , and outputs the modulated signal to the signal mapping section 103 .

[0040] Signal mapping section 103 maps (in other words, assigns or maps) DCI input from control section 101 to resources in the PDCCH region, for example. Signal mapping section 103 also maps DMRS and signals input from coding and modulation section 102 to resources in the PDSCH region. Signal mapping section 103 outputs the signals mapped to the resources to transmitting section 104.

[0041] The transmitting section 104 performs radio transmission processing such as frequency conversion using a carrier wave on the signal input from the signal mapping section 103 , and outputs the signal after radio transmission processing to the antenna 105 .

[0042] The antenna 105 radiates the signal input from the transmitter 104 (in other words, the downlink signal) toward the mobile station 200 .

[0043] [Configuration of Mobile Station] Fig. 8 is a block diagram showing an example configuration of mobile station 200 according to this embodiment. In Fig. 8, mobile station 200 has antenna 201, receiving section 202, signal separating section 203, channel estimating section 204, demodulating and decoding section 205, and control section 206.

[0044] The antenna 201 receives a downlink signal transmitted by the base station 100 (see, for example, FIG. 7 ) and outputs the signal to the receiving unit 202 .

[0045] Receiving section 202 performs radio reception processing such as frequency conversion on the signal input from antenna 201 , and outputs the signal after radio reception processing to signal separating section 203 .

[0046] Signal separating section 203 extracts (in other words, separates) DCI, for example, allocated to resources of the PDCCH region, from the signal input from receiving section 202, and outputs the DCI to control section 206. Furthermore, signal separating section 203 extracts (in other words, separates) data signals and DMRSs allocated to resources of the PDSCH region, based on information indicating resources of the PDSCH region and information indicating the position of the DMRS input from control section 206. Signal separating section 203 outputs the data signal to demodulating and decoding section 205, and outputs the DMRS to channel estimation section 204.

[0047] The channel estimation unit 204 performs channel estimation (for example, calculation of a channel estimation value) based on the DMRS input from the signal separation unit 203. The channel estimation unit 204 outputs information indicating the channel estimation value to the demodulation and decoding unit 205.

[0048] The demodulation and decoding unit 205 demodulates and decodes the data signal input from the signal separation unit 203 based on the channel estimation value input from the channel estimation unit 204. The demodulation and decoding unit 205 outputs the upper layer signal obtained by decoding to the control unit 206.

[0049] The control unit 206 identifies, for example, the PDSCH region and the position of the DMRS associated with the PDSCH region based on the upper layer signal input from the demodulation and decoding unit 205 and the DCI input from the signal separation unit 203.

[0050] In addition, the control unit 206 determines whether the position of the DMRS in the PDSCH (e.g., the position of the symbol) has been changed (in other words, shifted) from the reference position (e.g., the position of Assumption 1 shown in Figure 2).

[0051] The control section 206 outputs information relating to the PDSCH region and information relating to the position of the DMRS to the signal separation section 203 .

[0052] [Example of Operation of Base Station 100 and Mobile Station 200] Next, an example of operation of the base station 100 (see FIG. 7) and the mobile station 200 (see FIG. 8) will be described.

[0053] FIG. 9 is a flowchart showing an example of processing by the base station 100 and the mobile station 200.

[0054] Base station 100 notifies (in other words, sets) an upper layer signal to mobile station 200 (ST101). Mobile station 200 receives the uplink layer signal notified from base station 100.

[0055] The higher layer signal may include, for example, information related to LTE CRS (e.g., RateMatchPatternLTE-CRS) or information related to a band allocated to the mobile station 200 (e.g., active BWP). Furthermore, for example, the information related to the active BWP may include information related to subcarrier spacing (SCS) set in the mobile station 200. Note that this information may be notified to the mobile station 200 by at least one of higher layer parameters and downlink control information (e.g., DCI), or may be set in advance in the mobile station 200.

[0056] Base station 100 determines the content of DCI to be notified to mobile station 200 (ST102). The DCI may include, for example, the following information:

[0057] <PDSCH Allocation Information> The PDSCH allocation information may include, for example, information on frequency domain resources to which PDSCH (e.g., mapping type B) is allocated, and information on time domain resources to which PDSCH is allocated (e.g., start symbol and symbol length).

[0058] <PDSCH Transmission Band Information> The PDSCH transmission band information may include, for example, information about the BWP in which the PDSCH is transmitted (including, for example, information about the subcarrier spacing).

[0059] <Information Related to Orthogonal DMRS Port Based MU-MIMO> The information related to orthogonal DMRS port based MU-MIMO may include, for example, information indicating whether orthogonal DMRS port based MU-MIMO is operated for mobile station 200. The information related to orthogonal DMRS port based MU-MIMO may be explicitly notified or implicitly notified from base station 100 to mobile station 200, for example.

[0060] The information included in the DCI is not limited to the above-mentioned information, and may be other information.

[0061] Based on information configured in mobile station 200 (e.g., information included in higher layer parameters and DCI), base station 100 determines whether to set (in other words, change or shift) the position of the DMRS in the PDSCH to a position different from the configured position (e.g., the position of "Assumption 1" shown in FIG. 2) (ST103). For example, base station 100 may determine whether the condition for shifting the DMRS is "true" or "false."

[0062] If it is determined that the DMRS should be shifted (ST103: YES), base station 100 determines the position of the DMRS to be, for example, the nth symbol, which is different from the mth symbol set in mobile station 200 (ST104). In other words, the position of the DMRS set in mobile station 200 is shifted from the mth symbol to the nth symbol.

[0063] On the other hand, if it is determined that the DMRS is not to be shifted (ST103: NO), base station 100 does not change (shift) the position of the DMRS.

[0064] Base station 100 transmits a downlink signal to mobile station 200 (ST105). The downlink signal may include, for example, at least one of a PDSCH including a DMRS and a PDCCH including a DCI. Note that the DMRS is allocated to a position (e.g., a symbol) determined by base station 100.

[0065] For example, the mobile station 200 receives a downlink signal transmitted from the base station 100 and checks the information (in other words, the content) indicated in the DCI in the PDCCH included in the downlink signal (ST106). For example, the mobile station 200 may determine that the position of the DMRS is set to the m-th symbol based on the allocation information of the PDSCH.

[0066] Mobile station 200 determines, for example, based on the received higher layer signal and information indicated in the DCI, whether the position of the DMRS in the PDSCH has been set (in other words, changed or shifted) to a position (e.g., the nth symbol) different from the set position (e.g., the mth symbol) (ST107). For example, mobile station 200 may determine whether the condition for shifting the DMRS is "true" or "false."

[0067] If it is determined that the DMRS is to be shifted (ST107: YES), mobile station 200 determines the position of the DMRS to be, for example, the nth symbol, which is different from the mth symbol set in mobile station 200 (ST108). In other words, the position of the DMRS set in mobile station 200 is shifted from the mth symbol to the nth symbol.

[0068] On the other hand, if it is determined that the position of the DMRS is not to be shifted (ST107: NO), mobile station 200 does not change (shift) the position of the DMRS.

[0069] Mobile station 200 performs reception processing (for example, demodulation processing) of the PDSCH, for example, based on the DMRS allocated to the determined position (ST109).

[0070] Next, examples of DMRS allocation operations according to the present embodiment will be described.

[0071] <Operation Example 1-1> In operation example 1-1, for example, a method will be described in which the base station 100 and the mobile station 200 determine whether or not to change (in other words, shift) the position of a DMRS set at the 11th symbol (e.g., m=11) in an NR slot to the 12th symbol (n=12).

[0072] As an example, a case will be described in which the NR PDSCH for mobile station 200 is allocated to nine symbols from the fifth symbol to the thirteenth symbol in a slot, as shown in Fig. 10(a). In this case, for example, based on "Assumption 1" shown in Fig. 2, the position of the DMRS in the PDSCH is set to the eleventh symbol, which corresponds to l=6, as shown in Fig. 10(a).

[0073] 3, for example, a CRS can be placed in the 11th symbol in a slot, but a CRS cannot be placed in the 12th symbol. Therefore, for example, by setting the position of the DMRS to the 12th symbol, which is different from the 11th symbol (in other words, changing or shifting), it is possible to suppress collision between the DMRS in the NR PDSCH and the LTE CRS.

[0074] For example, if the content indicated in the configuration information of mobile station 200 satisfies at least one of the following conditions, base station 100 and mobile station 200 determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol configured in mobile station 200, as shown in FIG. 10(b) (for example, the processing in ST103 and ST107 shown in FIG. 9). In other words, in the processing in ST103 and ST107 shown in FIG. 9, base station 100 and mobile station 200 may determine that the condition for shifting the DMRS is "true" if the content indicated in the information configured in mobile station 200 (for example, information that enables identification (or estimation) of the placement of the LTE CRS) satisfies the following conditions:

[0075] Condition (1): "The mobile station 200 is not operating in an unlicensed band (e.g., also called NR-unlicensed (NR-U))." The NR frequency band (e.g., licensed band or unlicensed band) set for the mobile station 200 may be notified to the mobile station 200 by the base station 100, for example, by control information (e.g., upper layer signaling or DCI), or may be set in the mobile station 200.

[0076] For example, it is possible that DSS is not used in an unlicensed band. Therefore, when mobile station 200 operates in an unlicensed band, the DMRS included in the NR signal for mobile station 200 does not collide with the LTE CRS, and therefore the position of the DMRS (e.g., the 11th symbol) in the NR PDSCH does not need to be changed.

[0077] On the other hand, since DSS can be operated in a licensed band, for example, CRS may be allocated to the 11th symbol in a slot as shown in Fig. 3. Therefore, if the mobile station 200 is not operated in an unlicensed band, it may be determined that the LTE CRS and DMRS may overlap.

[0078] Therefore, for example, when condition (1) is satisfied, the base station 100 and the mobile station 200 may determine the location of the DMRS to be the 12th symbol, which is different from the 11th symbol. In other words, when the mobile station 200 is operating in a licensed band, the base station 100 and the mobile station 200 may determine the location of the DMRS to be the 12th symbol.

[0079] Condition (2): "The RRC parameter RateMatchPatternLTE-CRS is configured for the mobile station 200." For example, if RateMatchPatternLTE-CRS is configured for the mobile station 200, the LTE CRS may be configured in the LTE system, and therefore the DMRS in the NR PDSCH and the LTE CRS may overlap. For example, as shown in FIG. 3 , a CRS may be allocated to the 11th symbol in a slot, and therefore it may be determined that the DMRS in the NR PDSCH and the LTE CRS may overlap at the 11th symbol.

[0080] Therefore, when condition (2) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol.

[0081] Condition (3): "The RRC parameter RateMatchPatternLTE-CRS is configured for the mobile station 200, and the timing of the MBSFN subframe configured by this RRC parameter does not match the transmission timing of the DMRS." For example, as shown in Fig. 3, in an MBSFN subframe, the CRS may be located in the 0th or 1st symbol. Therefore, if the timing of the MBSFN subframe matches the transmission timing of the DMRS, the DMRS in the PDSCH and the LTE CRS cannot collide, and therefore the position of the DMRS in the NR PDSCH (e.g., the 11th symbol) does not need to be changed.

[0082] On the other hand, if the timing of the MBSFN subframe does not match the transmission timing of the DMRS, for example, if the timing of the non-MBSFN subframe matches the transmission timing of the DMRS, it may be determined that the DMRS in the PDSCH may collide with the LTE CRS, since the CRS may be placed in the 11th symbol, as shown in Figure 3.

[0083] Therefore, when condition (3) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol.

[0084] As described above, in an MBSFN subframe, a DMRS is not allocated to the 11th symbol. Therefore, condition (3) is a condition in which the DMRS and CRS are more likely to collide than condition (2).

[0085] Condition (4): "The mobile station 200 uses an active BWP with a subcarrier spacing (SCS) of 15 kHz." When the SCS set for the mobile station 200 in the NR system is 15 kHz, that is, when the subcarrier spacing is the same as that in the LTE system, for example, as shown in FIG. 3, it can be determined that the DMRS in the NR PDSCH and the LTE CRS may collide at the 11th symbol.

[0086] Therefore, when condition (4) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol.

[0087] Condition (5): "orthogonal DMRS port based MU-MIMO is in operation for the mobile station 200." When orthogonal DMRS port based MU-MIMO is notified to the mobile station 200, for example, by DCI, if the position of the DMRS is changed in at least one mobile station 200 among the multiple mobile stations 200 that are multiplexed using MU-MIMO, the orthogonality of the DMRS among the multiple mobile stations 200 may be lost.

[0088] Therefore, when condition (5) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol.

[0089] In other words, when condition (5) is satisfied, the position of the DMRS for multiple mobile stations 200 operating in orthogonal DMRS port based MU-MIMO is set to the 12th symbol. By setting the DMRS in this manner, even if the position of the DMRS for mobile station 200 operating in DSS is changed, the positions of the DMRS for other mobile stations 200 multiplexed in MU-MIMO are also changed accordingly, thereby making it possible to prevent the orthogonality of the DMRSs between multiple mobile stations 200 from being lost.

[0090] For example, in the example shown in FIG. 4 , when mobile station B is notified that orthogonal DMRS port based MU-MIMO is in operation, mobile station B may determine the position of the DMRS to be the 12th symbol, taking into consideration that even if DSS is not in operation for mobile station B, DSS may be in operation for another mobile station A that is multiplexed with MU-MIMO.

[0091] Condition (5) may be defined as, for example, "the DCI received by mobile station 200 implies orthogonal DMRS port based MU-MIMO."

[0092] Condition (6): "The DCI received by the mobile station 200 indicates allocation using PDSCH mapping type B." In allocation using PDSCH mapping type B, for example, as shown in FIG. d In the case of l=9, a DMRS in the PDSCH may be mapped to the 11th symbol corresponding to l=6. Also, for example, as shown in Fig. 3, a CRS may be mapped to the 11th symbol in a slot. Therefore, when PDSCH mapping type B is configured, a DMRS in the NR PDSCH and an LTE CRS may collide in the 11th symbol.

[0093] Therefore, when condition (6) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol.

[0094] Condition (7): "The DCI received by the mobile station 200 indicates allocation using PDSCH mapping type B, and the allocation is "9 symbols from the 5th symbol to the 13th symbol." As explained in condition (6), in allocation using PDSCH mapping type B, the length of the PDSCH is 9 symbols (for example, the length of the 13th symbol shown in FIG. 2). d In the case of l=9, a DMRS in a PDSCH may be mapped to the 11th symbol corresponding to l=6. Also, for example, as shown in FIG. 3, a CRS may be mapped to the 11th symbol in a slot. Therefore, when PDSCH mapping type B is configured, a DMRS in an NR PDSCH and an LTE CRS may collide in the 11th symbol.

[0095] Therefore, when condition (7) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the 12th symbol, which is different from the 11th symbol.

[0096] For example, as shown in FIG. 2, in the case of single symbol DMRS, the length of PDSCH is 10 symbols (for example, the length of d In the case where l=10, no DMRS is allocated to the 11th symbol (corresponding to l=7). Therefore, condition (7) is a condition in which the DMRS and CRS are more likely to collide than condition (6).

[0097] Conditions (1) to (7) have been explained above.

[0098] The base station 100 and the mobile station 200 may determine whether to position the DMRS at the 11th symbol or the 12th symbol based on, for example, any one or more of conditions (1) to (7).

[0099] According to operation example 1-1, for example, when a DMRS in an NR PDSCH may collide with an LTE CRS, base station 100 and mobile station 200 determine (in other words, change or shift) the position of the DMRS in the NR PDSCH to the 12th symbol, which does not collide with the CRS, based on information set in mobile station 200. By determining the DMRS position in this way, it is possible to avoid collision between the DMRS in the NR PDSCH and the LTE CRS.

[0100] Furthermore, for example, the base station 100 and the mobile station 200 may determine that orthogonal DMRS-based MU-MIMO can be implemented for the mobile station 200 if at least one of the above-mentioned conditions (1) to (7) is satisfied.

[0101] For example, base station 100 performs a DMRS shift for each of multiple mobile stations 200 that operate using orthogonal DMRS-based MU-MIMO. Furthermore, each mobile station 200 that operates using orthogonal DMRS-based MU-MIMO determines that a DMRS shift will also be performed for that mobile station 200, assuming that a DMRS shift may be performed in other mobile stations 200 that are MU-MIMO-multiplexed to avoid collisions between the DMRS and CRS. This determination reduces disruption of orthogonality between DMRS ports corresponding to multiple mobile stations 200 when orthogonal DMRS-based MU-MIMO is operated for the mobile station 200.

[0102] As described above, according to the operation example 1-1, for example, collision between the DMRS and the CRS can be avoided, and also according to the operation example 1-1, for example, orthogonality between the DMRS ports can be maintained.

[0103] In operation example 1-1, the case where m=11 and n=12 has been described, but the position of the DMRS after the change (in other words, after the shift) is not limited to the 12th symbol, and may be, for example, the 13th symbol or a symbol after the 10th symbol or a symbol before the 9th symbol. By changing to these symbols, it is possible to flexibly allocate the DMRS to a time position or interval suitable for improving the accuracy of channel estimation in mobile station 200, for example.

[0104] <Operation Example 1-2> In operation example 1-2, for example, a method is described in which the base station 100 and the mobile station 200 determine whether to change (in other words, shift) the position of a DMRS set at the 8th symbol (e.g., m=8) in an NR slot to the 9th symbol (e.g., n=9).

[0105] As an example, a case will be described in which the NR PDSCH for mobile station 200 is allocated to nine symbols from the fifth symbol to the thirteenth symbol in a slot, as shown in Fig. 11(a). In this case, for example, based on "Assumption 1" shown in Fig. 2, the position of the DMRS in the PDSCH is set to the eighth symbol corresponding to l=3, as shown in Fig. 11(a).

[0106] 3, for example, a CRS can be placed in the 8th symbol in a slot, but a CRS cannot be placed in the 9th symbol. Therefore, for example, by setting the position of the DMRS to the 9th symbol, which is different from the 8th symbol (in other words, changing or shifting), it is possible to suppress collision between the DMRS in the NR PDSCH and the LTE CRS.

[0107] In operation example 1-2, for example, when the contents indicated in the configuration information of the mobile station 200 satisfy at least one of conditions (1) to (7) described in operation example 1-1 and the following condition (8), the base station 100 and the mobile station 200 determine the position of the DMRS to be the 9th symbol, which is different from the 8th symbol set in the mobile station 200, as shown in Figure 11 (b) (for example, the processing of ST103 and ST107 shown in Figure 9).

[0108] Condition (8): Condition (8) is the case where “the RRC parameter RateMatchPatternLTE-CRS is set for the mobile station 200, the number of CRS ports set by this RRC parameter is 4, and the timing of the MBSFN subframe set by this RRC parameter does not match the transmission timing of the DMRS.”

[0109] An example of a case where condition (8) is satisfied is when the timing of a non-MBSFN subframe coincides with the transmission timing of a DMRS. For example, as shown in Figure 3, the number of CRS ports is four and a CRS can be placed in the eighth symbol in a non-MBSFN subframe, so that the DMRS in the NR PDSCH and the LTE CRS can overlap in the eighth symbol.

[0110] Therefore, when condition (8) is satisfied, base station 100 and mobile station 200 may determine the position of the DMRS to be the ninth symbol, which is different from the eighth symbol.

[0111] The base station 100 and the mobile station 200 may determine whether to position the DMRS at the 8th symbol or the 9th symbol based on, for example, any one or more of conditions (1) to (8).

[0112] According to operation example 1-2, for example, when a DMRS in an NR PDSCH may collide with an LTE CRS, base station 100 and mobile station 200 determine (in other words, change or shift) the position of the DMRS in the NR PDSCH to the 9th symbol, which does not collide with the CRS, based on information set in mobile station 200. By determining the DMRS position in this way, it is possible to avoid collision between the DMRS in the NR PDSCH and the LTE CRS.

[0113] Furthermore, for example, the base station 100 and the mobile station 200 may determine that orthogonal DMRS-based MU-MIMO can be implemented for the mobile station 200 if at least one of the above-mentioned conditions (1) to (8) is satisfied.

[0114] For example, base station 100 performs a DMRS shift for each of multiple mobile stations 200 that operate using orthogonal DMRS-based MU-MIMO. Furthermore, each mobile station 200 that operates using orthogonal DMRS-based MU-MIMO determines that a DMRS shift will also be performed for that mobile station 200, assuming that a DMRS shift may be performed in other mobile stations 200 that are MU-MIMO-multiplexed to avoid collisions between the DMRS and CRS. This determination reduces disruption of orthogonality between DMRS ports corresponding to multiple mobile stations 200 when orthogonal DMRS-based MU-MIMO is operated for the mobile station 200.

[0115] As described above, according to the operation example 1-2, for example, collision between the DMRS and the CRS can be avoided, and further, according to the operation example 1-2, for example, orthogonality between the DMRS ports can be maintained.

[0116] In operation example 1-2, the case where m = 8 and n = 9 has been described, but the position of the DMRS after the change (in other words, after the shift) is not limited to the ninth symbol, and may be, for example, the tenth symbol, the eleventh symbol, or a symbol after the seventh symbol or the sixth symbol. By changing to these symbols, it is possible to flexibly allocate the DMRS to a time position or interval suitable for improving the accuracy of channel estimation in mobile station 200, for example.

[0117] <Operation Example 1-3> Operation example 1-3 will describe a method in which, for example, the base station 100 and the mobile station 200 determine whether to change (in other words, shift) the positions of a DMRS (in other words, double symbol DMRS) set at the 10th and 11th symbols (for example, m=10 and 11) in an NR slot to the 12th and 13th symbols (for example, n=12 and 13).

[0118] As an example, a case will be described in which the NR PDSCH for mobile station 200 is allocated to nine symbols from the fifth symbol to the thirteenth symbol in a slot, as shown in Fig. 12(a). In this case, for example, based on "Assumption 1" shown in Fig. 2, the position of the DMRS in the PDSCH is set to the tenth and eleventh symbols corresponding to l=5, as shown in Fig. 12(a).

[0119] 3, for example, a CRS can be placed in the 8th symbol in a slot, but a CRS cannot be placed in the 9th symbol. Therefore, for example, by setting the position of the DMRS to the 9th symbol, which is different from the 8th symbol (in other words, changing or shifting), it is possible to suppress collision between the DMRS in the NR PDSCH and the LTE CRS.

[0120] In operation example 1-3, for example, when the contents indicated in the configuration information of the mobile station 200 satisfy at least one of conditions (1) to (7) described in operation example 1-1, the base station 100 and the mobile station 200 determine the position of the DMRS to be the 12th symbol and the 13th symbol, which are different from the 10th symbol and the 11th symbol set in the mobile station 200, as shown in FIG. 12(b) (for example, the processing of ST103 and ST107 shown in FIG. 9).

[0121] The base station 100 and the mobile station 200 may determine whether to position the DMRS at the 10th and 11th symbols or the 12th and 13th symbols, based on, for example, any one or more of conditions (1) to (7).

[0122] According to operation example 1-3, for example, when a DMRS in an NR PDSCH may collide with an LTE CRS, base station 100 and mobile station 200 determine (in other words, change or shift) the position of a double symbol DMRS in the NR PDSCH to the 12th and 13th symbols, which do not collide with the CRS, based on information set in mobile station 200. By determining the DMRS position in this way, it is possible to avoid collision between the double symbol DMRS in the NR PDSCH and the LTE CRS.

[0123] Also, similar to operation example 1-1, for example, the base station 100 and the mobile station 200 may determine that orthogonal DMRS-based MU-MIMO can be implemented for the mobile station 200 if at least one of the above-mentioned conditions (1) to (7) is satisfied.

[0124] For example, base station 100 performs a DMRS shift for each of multiple mobile stations 200 that operate using orthogonal DMRS-based MU-MIMO. Furthermore, each mobile station 200 that operates using orthogonal DMRS-based MU-MIMO determines that a DMRS shift will also be performed for that mobile station 200, assuming that a DMRS shift may be performed in other mobile stations 200 that are MU-MIMO-multiplexed to avoid collisions between the DMRS and CRS. This determination reduces disruption of orthogonality between DMRS ports corresponding to multiple mobile stations 200 when orthogonal DMRS-based MU-MIMO is operated for the mobile station 200.

[0125] As described above, according to the operation example 1-3, for example, collision between double symbol DMRS and CRS can be avoided. Furthermore, according to the operation example 1-3, for example, orthogonality between DMRS ports can be maintained.

[0126] In operation example 1-3, the cases where m=10 and 11 and n=12 and 13 have been described, but the positions of the DMRS after the change (in other words, after the shift) are not limited to the 12th and 13th symbols and may be, for example, the 9th and 10th symbols, or the two symbols before the 9th symbol. By changing to these symbols, it is possible to flexibly allocate the DMRS to a time position or interval suitable for improving the accuracy of channel estimation in mobile station 200, for example.

[0127] <Operation Example 1-4> In operation example 1-4, for example, a method is described in which the base station 100 and the mobile station 200 determine whether to change (in other words, shift) the position of a DMRS set at the 8th symbol (e.g., m=8) in an NR slot to the 10th symbol (e.g., n=10).

[0128] In operation example 1-4, for example, an active BWP having a subcarrier spacing of 30 kHz may be set for mobile station 200 (for example, the process of ST101 shown in FIG. 9).

[0129] Furthermore, the base station 100 may allocate the NR PDSCH to the mobile station 200, for example, to nine symbols from the fifth symbol to the thirteenth symbol in a slot as shown in FIG. 11(a), or to ten symbols from the fourth symbol to the thirteenth symbol in a slot as shown in FIG. 13 (for example, the processing of ST102 shown in FIG. 9).

[0130] Also, for example, base station 100 may allocate PDSCH to mobile station 200 in an active BWP having a subcarrier spacing of 30 kHz (for example, the process of ST102 shown in FIG. 9).

[0131] Furthermore, base station 100 may configure mobile station 200 to operate in orthogonal DMRS port based MU-MIMO (for example, the process in ST102 shown in FIG. 9).

[0132] For example, based on "Assumption 1" shown in FIG. 2, as shown in FIGS. 11(a) and 13, d l=3 or l=9 d The position of the DMRS in the PDSCH is set to the 8th symbol corresponding to l=4 in =10.

[0133] When the SCS for NR is 30 kHz, the time corresponding to one symbol is half that of the time corresponding to the SCS of LTE = 15 kHz. In other words, one symbol with SCS = 15 kHz is equivalent to two symbols with SCS = 30 kHz.

[0134] For example, in FIG. 3, the fourth symbol (or the eleventh symbol) in which a CRS is arranged in LTE with SCS = 15 kHz corresponds to the eighth and ninth symbols in NR with SCS = 30 kHz. Therefore, for example, in the eighth and ninth symbols in an NR slot with SCS = 30 kHz, a CRS can be arranged at a position equivalent to the fourth symbol (or the eleventh symbol) in SCS = 15 kHz. In contrast, a CRS cannot be arranged in the tenth symbol (e.g., the fifth or twelfth symbol in SCS = 15 kHz) in an NR slot with SCS = 30 kHz. Therefore, for example, by setting (in other words, changing or shifting) the position of a DMRS in an NR slot with SCS = 30 kHz to the tenth symbol, which is different from the eighth symbol, collision between a DMRS in an NR PDSCH and an LTE CRS can be suppressed.

[0135] In operation example 1-4, for example, when the contents indicated in the configuration information of the mobile station 200 satisfy at least one of conditions (1) to (3), (5), and (6) described in operation example 1-1 and the following conditions (4)' and (7)', the base station 100 and the mobile station 200 determine the position of the DMRS to be the 10th symbol, which is different from the 8th symbol, as shown in Figures 14(a) and 14(b) (for example, the processing of ST103 and ST107 shown in Figure 9).

[0136] Condition (4)': "The mobile station 200 uses an active BWP with a subcarrier spacing (SCS) of 30 kHz." As described above, when the SCS for NR is 30 kHz, the DMRS in the NR PDSCH and the LTE CRS may collide at the eighth symbol in the NR slot.

[0137] Therefore, when condition (4)' is satisfied, the base station 100 and the mobile station 200 may determine the position of the DMRS to be the 10th symbol (for example, the symbol one symbol later when SCS=15 kHz), which is different from the 8th symbol.

[0138] Condition (7)': "The DCI received by the mobile station 200 indicates allocation using PDSCH mapping type B, and the allocation is "9 symbols from the 5th symbol to the 13th symbol" or "10 symbols from the 4th symbol to the 13th symbol." As described above, in allocation using PDSCH mapping type B, the length of the PDSCH is 9 symbols (for example, the length of the 1 symbol shown in FIG. 2). d = 9), and the length of the PDSCH is 10 symbols (for example, the length d A DMRS in the PDSCH may be mapped to the 8th symbol, which corresponds to l=4 in the case of SCS=30 kHz (or SCS=10). Also, as described above, a CRS may be mapped to the 4th or 11th symbol in a slot with SCS=15 kHz, which corresponds to the 8th symbol in the case of SCS=30 kHz. Therefore, when PDSCH mapping type B is configured and the PDSCH length is 9 or 10 symbols, a DMRS in the NR PDSCH may collide with an LTE CRS in the 8th symbol in an NR slot.

[0139] Therefore, when condition (7)' is satisfied, the base station 100 and the mobile station 200 may determine the position of the DMRS to be the 10th symbol (for example, the symbol one symbol later when SCS=15 kHz), which is different from the 8th symbol.

[0140] The base station 100 and the mobile station 200 may determine whether to position the DMRS at the 8th symbol or the 10th symbol based on, for example, any one or more of conditions (1) to (3), (4)', (5), (6) and (7)'.

[0141] According to Operation Example 1-4, for example, when a DMRS in an NR PDSCH may collide with an LTE CRS, base station 100 and mobile station 200 determine (in other words, change or shift) the position of the DMRS in the NR PDSCH to the 10th symbol, where the DMRS does not collide with the CRS, based on information set in mobile station 200. By determining the DMRS position in this way, it is possible to avoid collision between the DMRS in the NR PDSCH and the LTE CRS, even if the NR SCS is different from the LTE SCS.

[0142] Furthermore, for example, the base station 100 and the mobile station 200 may determine that orthogonal DMRS-based MU-MIMO can be implemented for the mobile station 200 when at least one of the above-mentioned conditions (1) to (3), (4)', (5), (6), and (7)' is satisfied.

[0143] For example, base station 100 performs a DMRS shift for each of multiple mobile stations 200 that operate using orthogonal DMRS-based MU-MIMO. Furthermore, each mobile station 200 that operates using orthogonal DMRS-based MU-MIMO determines that a DMRS shift will also be performed for that mobile station 200, assuming that a DMRS shift may be performed in other mobile stations 200 that are MU-MIMO-multiplexed to avoid collisions between the DMRS and CRS. This determination reduces disruption of orthogonality between DMRS ports corresponding to multiple mobile stations 200 when orthogonal DMRS-based MU-MIMO is operated for the mobile station 200.

[0144] As described above, according to the operation example 1-4, for example, collision between the DMRS and the CRS can be avoided, and further, according to the operation example 1-4, for example, orthogonality between the DMRS ports can be maintained.

[0145] In operation example 1-4, the case where m=8 and n=10 has been described, but the position of the DMRS after the change (in other words, after the shift) is not limited to the 10th symbol, and may be, for example, the 11th symbol, the 12th symbol, or a symbol after the 7th symbol or the 6th symbol. By changing to these symbols, it is possible to flexibly allocate the DMRS to a time position or interval suitable for improving the accuracy of channel estimation in mobile station 200, for example.

[0146] As described above, in operation examples 1-1 to 1-4, a case has been described in which the position of a DMRS is determined based on the position of a DMRS and the position of a CRS that can be configured for mobile station 200 in Rel. 16. In other words, in operation examples 1-1 to 1-4, for example, base station 100 and mobile station 200 can identify symbols where a DMRS and a CRS may collide or symbols where a DMRS and a CRS may not collide, based on the configuration information of mobile station 200.

[0147] For example, the conditions described in operational examples 1-1 to 1-4 do not depend on whether or not there is overlap (in other words, collision) between the symbol in which the CRS is allocated and the symbol set as the DMRS for the mobile station 200. Therefore, in operational examples 1-1 to 1-4, if the above-described conditions are met, the base station 100 and the mobile station 200 can maintain orthogonality between the DMRS ports corresponding to, for example, multiple mobile stations 200 multiplexed in MU-MIMO by changing the allocation of the DMRS even if the CRS and the DMRS do not actually collide.

[0148] <Operation Example 1-5> In operation example 1-5, an operation example will be described in which, for example, base station 100 and mobile station 200 cannot determine whether or not there is a collision between DMRS and CRS based on the configuration information of mobile station 200.

[0149] For example, in operation example 1-5, a method is described in which the base station 100 and the mobile station 200 determine whether to change (in other words, shift) the position of a DMRS set to an arbitrary symbol in an NR slot to a different symbol.

[0150] In operation example 1-5, for example, an active BWP having a subcarrier spacing of 15 kHz, 30 kHz, or 60 kHz may be set for mobile station 200 (for example, the process of ST101 shown in FIG. 9).

[0151] Furthermore, the base station 100 may allocate the NR PDSCH to the mobile station 200, for example, to a frequency band in which the LTE CRS can be transmitted and to any time resource within a slot (for example, the processing of ST102 shown in FIG. 9).

[0152] Furthermore, for example, base station 100 may allocate the PDSCH to mobile station 200 in an active BWP having a subcarrier spacing of 15 kHz, 30 kHz, or 60 kHz (for example, the process in ST102 shown in FIG. 9).

[0153] Furthermore, base station 100 may configure mobile station 200 to operate in orthogonal DMRS port based MU-MIMO (for example, the process in ST102 shown in FIG. 9).

[0154] For example, the position of the DMRS in the PDSCH set based on "Assumption 1" shown in FIG. 2 is assumed to be the "xth symbol."

[0155] Base station 100 determines whether to change (in other words, shift) the position of the DMRS to a symbol (hereinafter referred to as the "y-th symbol") different from the x-th symbol set in mobile station 200 (for example, the process of ST103 shown in FIG. 9). For example, if the symbol in which the CRS is allocated overlaps with the x-th symbol set in mobile station 200, base station 100 may determine the position of the DMRS to be the y-th symbol, different from the x-th symbol.

[0156] For example, the base station 100 may determine whether the symbol in which the CRS is allocated and the x-th symbol in which the DMRS is allocated overlap, based on information about the LTE CRS (e.g., information about the allocation of the CRS) and information about resources configured in the mobile station 200 (e.g., information about allocated resources in the frequency domain and the time domain for the PDSCH). In other words, the base station 100 determines whether the CRS and the DMRS may collide in the x-th symbol. For example, if the base station 100 determines that the CRS and the DMRS may collide, the base station 100 may determine that the condition for shifting the DMRS is "true."

[0157] If the condition for shifting the DMRS is true (ST103: YES), base station 100 determines (in other words, changes or shifts) the position of the DMRS to the y-th symbol, which is different from the x-th symbol (ST104). For example, base station 100 may allocate (in other words, shift) the DMRS to the y-th symbol having a smaller symbol number among symbols that do not collide with a CRS after the x-th symbol.

[0158] If there is no symbol that does not collide with a CRS among the symbols after the x-th symbol, base station 100 may allocate a DMRS to the x-th symbol (in other words, do not shift).

[0159] Furthermore, mobile station 200 determines whether to change the position of the DMRS (xth symbol) set based on the control signal notified from base station 100 to a different position (yth symbol) (for example, the process of ST107 shown in FIG. 9 ). For example, if the symbol where the CRS is allocated overlaps with the xth symbol set in mobile station 200, mobile station 200 may determine the position of the DMRS to be the yth symbol, which is different from the xth symbol.

[0160] For example, similar to base station 100, mobile station 200 determines whether or not the symbol in which CRS is allocated and the x-th symbol in which DMRS is allocated may overlap (in other words, collide) based on information related to LTE CRS and PDSCH allocation information configured in mobile station 200. For example, if mobile station 200 determines that CRS and DMRS may collide, it may determine that the condition for shifting DMRS is "true."

[0161] If the condition for shifting the DMRS is true (ST107: YES), mobile station 200 determines that the position of the DMRS has been determined (in other words, changed or shifted) to the y-th symbol, which is different from the x-th symbol (ST108). For example, mobile station 200 may determine that the DMRS has been allocated (in other words, shifted) to the y-th symbol, which has a smaller symbol number among symbols after the x-th symbol that do not collide with the CRS.

[0162] If there is no symbol after the xth symbol that does not collide with a CRS, the mobile station 200 may determine that a DMRS is placed in the xth symbol (in other words, may determine that there is no shift).

[0163] According to operation example 1-5, for example, when a DMRS in an NR PDSCH may collide with an LTE CRS, base station 100 and mobile station 200 determine (in other words, change or shift) the position of the DMRS in the NR PDSCH to another symbol that does not collide with the CRS. By determining the DMRS position in this way, it is possible to avoid collision between the DMRS in the NR PDSCH and the LTE CRS.

[0164] The subcarrier spacing set in the mobile station 200 is not limited to 15 kHz, 30 kHz, and 60 kHz, and may be other spacings.

[0165] Furthermore, in operation example 1-5, the y-th symbol is not limited to the smallest-numbered symbol among the symbols after the x-th symbol that do not collide with a CRS, but may be, for example, the second-smallest-numbered symbol among the symbols that do not collide with a CRS, or a symbol after the third-smallest-numbered symbol. Alternatively, the y-th symbol may be a symbol that does not collide with a CRS before the x-th symbol. By changing to these symbols, for example, it is possible to flexibly allocate DMRSs to time positions or intervals that are suitable for improving the accuracy of channel estimation in mobile station 200.

[0166] In addition to determining whether or not a DMRS and a CRS may collide, the base station 100 and the mobile station 200 may also determine whether or not to change the location of the DMRS configured in the mobile station 200, for example, based on whether or not the content indicated in the configuration information of the mobile station 200 satisfies at least one of the above-mentioned conditions (1), (3), (5), and (8).

[0167] Furthermore, for example, when at least one of the above conditions (1), (3), (5), and (8) is satisfied, the base station 100 and the mobile station 200 may determine that orthogonal DMRS-based MU-MIMO can be implemented for the mobile station 200. For example, the base station 100 performs a DMRS shift for each of the multiple mobile stations 200 in which orthogonal DMRS-based MU-MIMO is implemented. Furthermore, each mobile station 200 in which orthogonal DMRS-based MU-MIMO is implemented determines that a DMRS shift will be implemented for that mobile station 200 as well, assuming that a DMRS shift may be implemented in other mobile stations 200 in which the MU-MIMO is multiplexed to avoid collision between the DMRS and CRS. This determination reduces the loss of orthogonality between the DMRS ports corresponding to the multiple mobile stations 200 when orthogonal DMRS-based MU-MIMO is implemented for the mobile station 200.

[0168] An example of the operation of DMRS allocation has been described above.

[0169] As described above, in this embodiment, base station 100 and mobile station 200 determine the allocation of DMRSs in the NR PDSCH based on, for example, information configured in mobile station 200 (in other words, information capable of identifying the allocation of LTE CRS). By determining this DMRS allocation, for example, base station 100 operating DSS can appropriately allocate DMRSs and avoid collisions between DMRSs and CRSs. Furthermore, by determining this DMRS allocation, for example, orthogonality between DMRS ports can be maintained. Furthermore, even when DSS is operated, mobile station 200 can appropriately determine the allocation of DMRSs and receive the NR PDSCH.

[0170] (Variation 1 of Embodiment 1) In embodiment 1, when DMRS is allocated to multiple symbols within a slot, base station 100 and mobile station 200 may simultaneously change (in other words, shift) the multiple symbols in which DMRS is allocated.

[0171] For example, if the positions of the DMRSs in "Assumption 1" shown in FIG. 2 are the 8th and 11th symbols, the base station 100 and the mobile station 200 may change the positions of their respective DMRSs to the 9th and 12th symbols.

[0172] This change in DMRS allocation makes it possible to avoid collisions between multiple DMRSs and CRSs.

[0173] (Variation 2 of First Embodiment) In the first embodiment, for example, the information about the LTE system (for example, the RRC parameter RateMatchPatternLTE-CRS) notified from the base station 100 to the mobile station 200 in the process of ST101 shown in FIG. 9 may be information about the CRS of an LTE component carrier (CC) operating in any of the following bands: (1) the system band of the NR component carrier in which the base station 100 and the mobile station 200 operate, (2) any BWP set in the mobile station 200, (3) the active BWP used for transmission to the mobile station 200, and (4) the allocated band of the PDSCH transmitted to the mobile station 200.

[0174] Furthermore, if there are multiple LTE component carriers in the above band, the base station 100 may notify the mobile station 200 of a parameter indicating information related to CRS for one or multiple LTE component carriers.

[0175] For example, if multiple parameters are notified, the base station 100 and the mobile station 200 may determine whether to change the position of the DMRS based on one or more parameters (for example, the processing of ST103 and ST107 shown in FIG. 9).

[0176] Furthermore, the base station 100 and the mobile station 200 may determine whether to change the location of the DMRS based on some of the multiple parameters. For example, the base station 100 and the mobile station 200 may operate based on parameters including a larger number of CRS ports among the multiple parameters, or may operate based on parameters in which non-MBSFN subframes are set more frequently. By using these parameters, the location of the DMRS is determined taking into consideration, for example, a situation in which the CRS can be allocated to more resources, thereby reducing the possibility of collision between the CRS and the DMRS.

[0177] Furthermore, base station 100 may notify mobile station 200 of parameters based on which the mobile station 200 determines whether to change the location of the DMRS.

[0178] (Variation 3 of Embodiment 1) In Embodiment 1, the condition for determining whether to change the position of the DMRS may be, for example, information known between the base station 100 and the mobile station 200, or information notified from the base station 100 to the mobile station 200 by a control signal such as an upper layer signal or DCI.

[0179] Alternatively, information indicating the result of determining whether or not to change the location of the DMRS may be transmitted from base station 100 to mobile station 200 by a control signal such as a higher layer signal or DCI.

[0180] This notification enables mobile station 200 to accurately determine whether the position of the DMRS transmitted by base station 100 has changed.

[0181] (Fourth Variation of First Embodiment) In the first embodiment, the fact that mobile station 200 is operated in orthogonal DMRS port based MU-MIMO may be implicitly notified by, for example, DCI related to antenna port mapping notifying that "all the remaining orthogonal antenna ports are not associated with transmission of PDSCH to another UE."

[0182] (Fifth Variation of First Embodiment) In the first embodiment, the position of the DMRS received by mobile station 200 that does not operate orthogonal DMRS-based MU-MIMO may be shifted as shown in Fig. 15. This can mitigate, for example, degradation of reception accuracy due to collision of DMRS between cells.

[0183] (Variation 6 of Embodiment 1) In Embodiment 1, the parameters included in the conditions of each of the above operation examples are not limited to RateMatchPatternLTE-CRS, but may be, for example, parameters related to at least CRS or MBSFN subframes, and may be higher layer parameters having names different from RateMatchPatternLTE-CRS, or parameters included in control signals such as DCI, etc.

[0184] (Embodiment 2) For example, when multiple DMRSs are placed within a slot, as described in embodiment 1, changing the position of a DMRS that may collide with a CRS may change the positional relationship (e.g., time interval) between the DMRS whose position has been changed and other DMRSs (in other words, DMRSs whose position has not been changed).

[0185] For example, the greater the time interval between DMRSs, the more likely it is that the accuracy of channel estimation between those DMRSs will deteriorate.

[0186] Furthermore, for example, the smaller the time interval between DMRSs, the less effective it may be to allocate the DMRSs to multiple symbols. In other words, the smaller the time interval between DMRSs, the more overhead caused by the DMRSs increases, and the less efficient resource utilization may be.

[0187] In this embodiment, a DMRS allocation method that suppresses degradation of channel estimation accuracy and a DMRS allocation method that improves resource utilization efficiency will be described.

[0188] The base station and mobile station according to this embodiment have the same basic configuration as base station 100 and mobile station 200 according to the first embodiment.

[0189] Next, examples of DMRS allocation operations according to the present embodiment will be described.

[0190] <Operation Example 2-1> In operation example 2-1, for example, when DMRSs are allocated to multiple symbols within a slot, the base station 100 and the mobile station 200 change (in other words, shift) the positions of the DMRSs that may collide with the CRS, as well as the DMRSs that may not collide with the CRS.

[0191] As an example, a case will be described in which, as shown in FIG. 16(a), NR PDSCH is allocated to nine symbols from the fifth symbol to the thirteenth symbol within a BWP with a subcarrier spacing of 15 kHz for a mobile station 200.

[0192] In this case, for example, based on "Assumption 1" shown in FIG. 2, the positions of the DMRS in the PDSCH are set to the 5th, 8th, and 11th symbols (l=0, 3, 6).

[0193] Also, for example, the base station 100 and the mobile station 200 determine that the CRS can be placed in at least the seventh, eighth, and eleventh symbols within the slot, as shown in FIG.

[0194] In this case, the base station 100 and the mobile station 200 determine that the DMRS and the CRS may collide in the eighth and eleventh symbols, for example.

[0195] Therefore, base station 100 may change (in other words, shift) the positions of DMRSs that can be placed in the 8th and 11th symbols, and the positions of DMRSs that can be placed in the 5th symbol. For example, base station 100 may change the DMRSs in the 5th, 8th, and 11th symbols shown in Figure 16(a) to the 6th, 9th, and 12th symbols, respectively, as shown in Figure 16(b).

[0196] Furthermore, similar to base station 100, mobile station 200 may determine that the DMRSs at the fifth, eighth, and eleventh symbols shown in FIG. 16(a) are allocated to the sixth, ninth, and twelfth symbols, respectively, as shown in FIG. 16(b).

[0197] In operation example 2-1, for example, when the base station 100 and the mobile station 200 change the position of at least one DMRS among multiple DMRSs in a slot, they change the positions of the remaining DMRSs based on the changed DMRS position (in other words, the change in position). For example, as shown in Figures 16(a) and 16(b), three DMRSs in the PDSCH are each shifted one symbol backward from their positions set in the mobile station 200 (for example, positions based on "Assumption 1"). In other words, as shown in Figure 16(b), the allocation interval between DMRSs after the change (for example, three symbols) remains the same as the allocation interval between DMRSs before the change (for example, three symbols).

[0198] With this DMRS allocation, even when the positions of the DMRSs are changed, the allocation intervals between multiple DMRSs in the time domain do not change, so that it is possible to suppress degradation of channel estimation accuracy due to DMRSs.

[0199] <Operation Example 2-2> In Operation Example 2-2, for example, when DMRSs are allocated to multiple symbols within a slot, the base station 100 and the mobile station 200 determine not to transmit (in other words, drop) one of two DMRSs whose time interval is equal to or less than a threshold in the determined DMRS allocation (in other words, the changed position).

[0200] As an example, a case will be described in which, as shown in FIG. 17(a), NR PDSCH is allocated to nine symbols from the fifth symbol to the thirteenth symbol within a BWP with a subcarrier spacing of 30 kHz for a mobile station 200.

[0201] Here, the threshold value for the time interval between DMRSs used to determine whether to drop a DMRS is set to 1 symbol. Note that the threshold value is not limited to 1 symbol, and may be 2 symbols or more.

[0202] In this case, for example, based on "Assumption 1" shown in FIG. 2, the positions of the DMRS in the PDSCH are set to the 5th, 8th, and 11th symbols (l=0, 3, 6).

[0203] Also, for example, the base station 100 and the mobile station 200 determine that the LTE CRS (e.g., 15 kHz SCS) can be allocated to at least the eighth symbol in a slot. In this case, the base station 100 and the mobile station 200 determine that the DMRS and the CRS can collide in the eighth symbol, for example.

[0204] Therefore, the base station 100 and the mobile station 200 determine (in other words, change or shift) the position of the DMRS to, for example, the 10th symbol, which is different from the 8th symbol. In this case, the determined allocation of the DMRS is the 5th, 10th, and 11th symbols.

[0205] Here, since the interval between the DMRSs that can be placed in the 10th symbol and the 11th symbol is less than or equal to the threshold (1 symbol), the base station 100 and the mobile station 200 may determine to drop the DMRS that can be placed in the 10th symbol, for example, as shown in FIG. 17(b).

[0206] Therefore, as shown in FIG. 17(b), the base station 100 may transmit the DMRS in the fifth and eleventh symbols, and the mobile station 200 may receive the DMRS in the fifth and eleventh symbols.

[0207] Furthermore, for example, base station 100 may transmit another signal (for example, PDSCH) in the 10th symbol from which the DMRS is dropped, as shown in FIG. 17(b).

[0208] For example, as shown in Figure 17(b), when a DMRS is allocated to the 11th symbol, the channel estimation accuracy is comparable to when a DMRS is allocated to the 10th and 11th symbols. In operation example 2-2, for example, as shown in Figure 17(b), the DMRS is dropped in the 10th symbol, so that it is possible to suppress deterioration in channel estimation accuracy and suppress an increase in overhead due to the DMRS. Furthermore, since another signal is allocated to the 10th symbol from which the DMRS has been dropped, it is possible to improve resource utilization efficiency.

[0209] In Figure 17 (b), we have explained the case where the DMRS in the 10th symbol is dropped out of the DMRSs that can be placed in the 10th and 11th symbols with an interval less than or equal to a threshold, but the DMRS that is dropped may also be the DMRS in the 11th symbol.

[0210] The embodiments of the present disclosure have been described above.

[0211] (Other Embodiments) In the above-described embodiments, downlink communication is assumed in which a base station is a transmitting device and a mobile station is a receiving device. However, an embodiment of the present disclosure is not limited to this, and may be applied to uplink communication in which a mobile station is a transmitting device and a base station is a receiving device, or communication between mobile stations, i.e., sidelink communication.

[0212] Furthermore, in the above embodiments, the number of symbols constituting a slot is 14, but the number of symbols constituting a slot is not limited to 14, and may be another number (for example, 12 symbols).

[0213] Furthermore, in the above embodiments, a case has been described in which the position (e.g., symbol) of a DMRS is changed (in other words, shifted). However, the signal whose position is changed is not limited to a DMRS, and other signals may be used. Furthermore, in the above embodiments, a case has been described in which collision between a DMRS and a CRS is avoided by determining the DMRS position. However, the signal that takes into consideration collision with a DMRS is not limited to a CRS, and may be other signals different from a CRS. For example, an embodiment of the present disclosure may be applied to the following reference signals, channels, or other signals in NR or LTE, instead of at least one of a DMRS and a CRS:Phase Tracking Reference Signal (PT-RS, PTRS) Channel State Information Reference Signal (CSI-RS) Sounding Reference Signal (SRS) Tracking Reference Signal (TRS) Discovery Reference Signal (Discovery Signal, DRS) Primary Synchronization Signal (PSS) Secondary Synchronization Signal (SSS) Downlink Control Channel (PDCCH) Downlink Shared Channel (PDSCH) Uplink Control Channel (PUCCH) Uplink Shared Channel (PUSCH) Uplink Control Channel (PUCCH) Uplink Shared Channel (PUSCH) Physical Broadcast Channel (PBCH) - Physical Control Format Indicator Channel (PCFICH) - Physical HARQ Indicator Channel (PHICH) - Physical Multicast Channel (PMCH).

[0214] Furthermore, in the above-described embodiments, the PDSCH mapping method is not limited to PDSCH mapping type B. The PDSCH mapping method may be, for example, PDSCH mapping type A or another mapping method. An embodiment of the present disclosure can be applied, for example, to a case where a DMRS and a CRS may collide, regardless of the PDSCH mapping method.

[0215] Furthermore, in each of the above embodiments, when changing (shifting) the position of a DMRS, the DMRS may be changed to a different frequency position. For example, a DMRS belonging to a certain DMRS CDM group may be changed to a frequency position corresponding to another DMRS CDM group. This allows for more flexible avoidance of collisions with CRSs.

[0216] Furthermore, in the above-described embodiments, the "higher layer signal" may also be called, for example, an "RRC signal" or a "MAC signal."

[0217] Furthermore, in the above-described embodiments, a "reference signal" may also be called, for example, a "reference signal" or a "pilot signal." Furthermore, a DMRS may also be referred to as a "DM-RS."

[0218] Furthermore, in each of the above embodiments, the unit of time resource is not limited to slot and symbol, but may be other time resource unit such as frame, subframe, or subslot.

[0219] The present disclosure can be realized by software, hardware, or software integrated with hardware. Each functional block described in the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit. 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 inputs and outputs. Depending on the level of integration, an LSI may be referred to as an IC, system LSI, super LSI, or ultra LSI. The integrated circuit implementation is not limited to LSIs, and may be realized using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, a field programmable gate array (FPGA), which can be programmed after LSI fabrication, or a reconfigurable processor, which allows the connections and settings of circuit cells within an LSI to be reconfigured, may also be used. The present disclosure may be realized as digital or analog processing. 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 may be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0220] 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 radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both functions. The radio 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.

[0221] The communication devices are not limited to portable or mobile devices, but also include any kind of non-portable or fixed equipment, devices, and systems, such as smart home devices (such as home appliances, lighting equipment, smart meters or measuring devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0222] Communications include data communications via cellular systems, wireless LAN systems, communication satellite systems, and the like, as well as data communications via combinations of these.

[0223] 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.

[0224] 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.

[0225] A receiving device according to one embodiment of the present disclosure includes a control circuit that determines the arrangement of a second reference signal based on information that can identify the arrangement of a first reference signal, and a receiving circuit that receives the second reference signal based on the determined arrangement.

[0226] In one embodiment of the present disclosure, if the content indicated in the information satisfies a certain condition, the control circuit determines the position of the second reference signal to be a symbol different from the symbol set in the receiving device.

[0227] In one embodiment of the present disclosure, the condition does not depend on whether or not the symbol in which the first reference signal is placed overlaps with the symbol set in the second reference signal for the receiving device.

[0228] In one embodiment of the present disclosure, based on the information, when a first symbol in which the first reference signal is placed overlaps with a second symbol set as the second reference signal for the receiving device, the control circuit determines the position of the second reference signal to be a third symbol different from the second symbol.

[0229] In one embodiment of the present disclosure, the control circuit determines whether the first symbol and the second symbol overlap based on allocation information of data including the second reference signal and information regarding the placement of the first reference signal.

[0230] In one embodiment of the present disclosure, the control circuit determines the position of the second reference signal to be the third symbol if the content indicated in the information satisfies a certain condition.

[0231] In one embodiment of the present disclosure, the condition does not depend on whether the first symbol and the second symbol overlap or not.

[0232] In one embodiment of the present disclosure, when the control circuit changes the position of at least one reference signal among the plurality of second reference signals, the control circuit changes the positions of the remaining reference signals based on the position of the at least one reference signal.

[0233] In one embodiment of the present disclosure, the control circuit determines not to transmit one of the two second reference signals whose time interval is equal to or less than a threshold in the determined arrangement.

[0234] A transmitting device according to one embodiment of the present disclosure includes a control circuit that determines the arrangement of a second reference signal based on information that can identify the arrangement of a first reference signal, and a transmitting circuit that transmits the second reference signal in the determined arrangement.

[0235] In a receiving method according to one embodiment of the present disclosure, a receiving device determines the allocation of a second reference signal based on information capable of identifying the allocation of a first reference signal, and receives the second reference signal based on the determined allocation.

[0236] In a transmission method according to one embodiment of the present disclosure, a transmitting device determines the placement of a second reference signal based on information capable of identifying the placement of a first reference signal, and transmits the second reference signal in the determined placement.

[0237] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2019-149144, filed on August 15, 2019, are incorporated herein by reference in their entirety.

[0238] An embodiment of the present disclosure is useful in a mobile communication system.

[0239] 100 Base station 101, 206 Control unit 102 Coding and modulation unit 103 Signal mapping unit 104 Transmitting unit 105, 201 Antenna 200 Mobile station 202 Receiving unit 203 Signal separation unit 204 Channel estimation unit 205 Demodulation and decoding unit

Claims

1. A receiving device comprising: a control circuit that determines the arrangement of a second reference signal in a second system based on information that can identify the arrangement of a first reference signal in a first system; and a receiving circuit that receives the second reference signal based on the determined arrangement.

2. The receiving device according to claim 1, wherein the control circuit determines the position of the second reference signal to be a symbol different from the symbol set in the receiving device when the content indicated in the information satisfies a certain condition.

3. The receiving device according to claim 2, wherein the condition does not depend on whether or not the symbol in which the first reference signal is assigned overlaps with the symbol set in the second reference signal for the receiving device.

4. The receiving device according to claim 1, wherein, based on the information, when a first symbol in which the first reference signal is placed overlaps with a second symbol set for the second reference signal for the receiving device, the control circuit determines the position of the second reference signal to be a third symbol different from the second symbol.

5. The receiving device according to claim 4, wherein the control circuit determines whether the first symbol and the second symbol overlap based on allocation information for data including the second reference signal and information regarding the placement of the first reference signal.

6. The receiving device according to claim 4, wherein the control circuit determines the position of the second reference signal to be the third symbol when the content indicated in the information satisfies a certain condition.

7. The receiving device according to claim 6, wherein the condition does not depend on whether the first symbol and the second symbol overlap.

8. The receiving device according to claim 1, wherein when the control circuit changes the position of at least one reference signal among the plurality of second reference signals, the control circuit changes the positions of the remaining reference signals based on the position of the at least one reference signal.

9. The receiving device according to claim 1, wherein the control circuit determines not to transmit one of the two second reference signals whose time interval is equal to or less than a threshold in the determined allocation.

10. A transmitting device comprising: a control circuit that determines the arrangement of a second reference signal in a second system based on information that can identify the arrangement of a first reference signal in a first system; and a transmitting circuit that transmits the second reference signal in the determined arrangement.

11. A receiving method comprising: a receiving device determining an arrangement of a second reference signal in a second system based on information capable of identifying an arrangement of a first reference signal in a first system; and receiving the second reference signal based on the determined arrangement.

12. A transmission method, comprising: a transmitting device determining an arrangement of a second reference signal in a second system based on information capable of identifying an arrangement of a first reference signal in a first system; and transmitting the second reference signal in the determined arrangement.