User equipment, base station, and method implemented by the user equipment

Abstract

It provides a new solution for transmitting and receiving reference signals. [Solution] The user equipment of the present disclosure comprises: means for receiving downlink control information from a base station; means for determining, based on the downlink control information, that a cyclic shift field corresponds to either a first reference signal sequence or a second reference signal sequence depending on the value of the cyclic shift field; means for determining which of the first reference signal sequence or the second reference signal sequence the cyclic shift field corresponds to; and means for generating the one of the first reference signal sequence or the second reference signal sequence based on the downlink control information.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to wireless communication technologies, and more particularly to a method and apparatus for transmitting a reference signal and a method and apparatus for receiving a reference signal. [Background technology]

[0002] Multi-antenna technology can significantly increase the data rate and reliability of wireless communication systems. Performance is especially improved when both the transmitter and receiver have multiple antennas, resulting in a multiple-input multiple-output (MIMO) communication channel. Such systems and / or related technologies are commonly referred to as MIMO.

[0003] The Long Term Evolution (LTE) standard is currently rolling out enhanced MIMO support. Core components of LTE support MIMO antenna deployments and MIMO-related technologies. Currently, one-dimensional (horizontal) antenna arrays can provide flexible beam adaptation in the azimuth domain only through horizontal precoding, while a fixed down-tilt is applied in the vertical direction.

[0004] Recently, it has been shown that the full MIMO capability can be exploited by utilizing a two-dimensional (2D) antenna plane, allowing user-specific elevation beamforming and spatial multiplexing in the vertical domain. Furthermore, it has been proposed that the uplink (UL) demodulation reference signal (DMRS) supports additional orthogonal ports for partial overlap.

[0005] Also, when a high center frequency is used, the channel variation in the time domain is slow, so sparse RS can be used in the time domain. In other words, in future 5G communications, in order to reduce overhead, only one or a few symbols are proposed in the time domain for RS transmission, and Zadoff-Chu (ZC) sequences are proposed to be used in a novel subframe structure. For illustrative purposes, FIG. 1 shows one of the novel subframe structures, in which there is only one symbol in one TTI for RS transmission. However, it will be understood that in another possible novel subframe structure, the symbol may be located in other positions and / or may have one or more UL / DL symbols.

[0006] Thus, in future 5G communications, only one or a few symbols of DMRS may be used for both UL and DL (Down Link). In such cases, the use of more orthogonal ports in partially overlapping BWs should be considered to support higher order Multi-User MIMO (MU-MIMO).

[0007] Therefore, new DMRS designs, as well as new reference signal transmission and reception solutions, are required in the art to adapt new subframe structures to new channel characteristic variations in the time domain and to support more users or more layers. Summary of the Invention [Problem to be solved by the invention]

[0008] In the present disclosure, a new solution for transmitting and receiving reference signals is provided to alleviate or at least mitigate at least some of the problems in the prior art. [Means for solving the problem]

[0009] According to a first aspect of the present disclosure, there is provided a method for transmitting a reference signal, the method can include receiving a reference signal configuration indication, where a reference signal resource is divided into at least two reference signal groups, the reference signal configuration indication indicating a reference signal configuration including a reference signal group configuration, and transmitting a reference signal using a reference signal sequence in the reference signal group indicated by the reference signal group configuration, where the reference signal sequence can be multiplexed with other layers or other users in different reference signal groups.

[0010] In a second aspect of the present disclosure, a method for receiving a reference signal is provided, which may include transmitting a reference signal configuration indication, where a reference signal resource is divided into at least two reference signal groups, the reference signal configuration indication indicating a reference signal configuration including a reference signal group configuration, and receiving the transmitted reference signal by using a reference signal sequence in the reference signal group indicated by the reference signal group configuration, where the reference signal sequence may be multiplexed with other layers or other users in different reference signal groups.

[0011] In a third aspect of the present disclosure, an apparatus for transmitting a reference signal is provided, which may include an indication receiving module configured to receive a reference signal configuration indication, where a reference signal resource is divided into at least two reference signal groups, the reference signal configuration indication indicates a reference signal configuration including a reference signal group configuration, and a signal transmitting module configured to transmit a reference signal using a reference signal sequence in the reference signal group indicated by the reference signal group configuration, where the reference signal sequence can be multiplexed with other layers or other users in different reference signal groups.

[0012] In a fourth aspect of the present disclosure, an apparatus for receiving a reference signal is provided, which may include: an indication transmitting module configured to transmit a reference signal configuration indication, where a reference signal resource is divided into at least two reference signal groups, the reference signal configuration indication indicates a reference signal configuration including a reference signal group configuration, and a signal receiving module configured to receive a reference signal transmitted by using a reference signal sequence in the reference signal group indicated by the reference signal group configuration, and the reference signal sequence may be multiplexed with other layers or other users in different reference signal groups.

[0013] According to a fifth aspect of the present disclosure there is provided a computer readable storage medium having computer program code implemented thereon, the program code being configured, when executed, to cause an apparatus to perform operations in a method according to any embodiment of the first aspect.

[0014] According to a sixth aspect of the present disclosure there is further provided a computer readable storage medium having computer program code implemented thereon, the program code being configured, when executed, to cause an apparatus to perform operations in the method according to any embodiment of the second aspect.

[0015] According to a seventh aspect of the present disclosure there is provided a computer program product comprising a computer readable storage medium according to the fifth aspect.

[0016] According to an eighth aspect of the present disclosure there is provided a computer program product having a computer readable storage medium according to the sixth aspect. Effect of the Invention

[0017] With the embodiments of the present disclosure, a novel solution is provided for reference signal transmission and reception, in which reference signal resources are divided into at least two reference signal groups, and reference signals for different layers or users can be multiplexed into different reference signal groups, so that more mu-users with unequal bandwidth allocation can be supported with no significant channel estimation loss and PAPR problems. [Brief description of the drawings]

[0018] The above and other features of the present disclosure will become apparent through the detailed description of the embodiments described in the following with reference to the accompanying drawings, in which like reference numerals represent the same or similar components. [Figure 1] FIG. 1 illustrates a schematic of one of the possible UL symbols in the newly proposed subframe structure with reduced UL symbols. [Diagram 2] FIG. 2 illustrates a DMRS pattern in an existing communication system. [Diagram 3] FIG. 3 illustrates a schematic of the assignment of cyclic shifts to n(1) DMRS values. [Figure 4] FIG. 4 illustrates a schematic diagram of the allocation of the cyclic shift field in the DCI format associated with the uplink to n(2) DMRS, λ, and [w(λ)(0) w(λ)(1)]. [Diagram 5] FIG. 5 illustrates a flow chart of a method for transmitting a reference signal according to an embodiment of the present disclosure. [Figure 6A] FIG. 6A illustrates a schematic diagram of an example of a DMRS pattern in a frequency division multiplexing (FDM) mode based on DMRS grouping according to one embodiment of the present disclosure. [Figure 6B] FIG. 6B illustrates a schematic example of a DMRS pattern in FDM mode based on DMRS grouping according to one embodiment of the present disclosure. [Figure 7]FIG. 7 illustrates a schematic example of a DMRS pattern in a time division multiplexing (TDM) mode based on DMRS grouping according to one embodiment of the present disclosure. [Figure 8A] FIG. 8A illustrates a schematic example of a possible DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with one embodiment of the present disclosure. [Figure 8B] FIG. 8B illustrates a schematic example of a possible DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with one embodiment of the present disclosure. [Figure 8C] FIG. 8C illustrates a schematic example of a possible DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with one embodiment of the present disclosure. [Figure 8D] FIG. 8D illustrates a schematic example of a possible DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with one embodiment of the present disclosure. [Figure 8E] FIG. 8E illustrates a schematic example of a possible DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with one embodiment of the present disclosure. [Figure 8F] FIG. 8F illustrates a schematic example of a possible DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with one embodiment of the present disclosure. [Figure 9] FIG. 9 illustrates a schematic diagram of an example of an indication technique for indicating a DMRS group configuration, according to one embodiment of the present disclosure. [Figure 10] FIG. 10 illustrates a schematic diagram of another indication technique for indicating a DMRS group configuration according to another embodiment of the present disclosure. [Figure 11] FIG. 11 illustrates a schematic diagram of a further indication technique for indicating a DMRS group configuration according to another embodiment of the present disclosure. [Figure 12] FIG. 12 illustrates a schematic diagram of a DMRS configuration for four new user equipments according to one embodiment of the present disclosure. [Figure 13]FIG. 13 illustrates a schematic diagram of DMRS signals transmitted in REs for UEi and UEj according to one embodiment of the present disclosure. [Figure 14] FIG. 14 illustrates a schematic diagram of a DMRS configuration for a legacy user equipment and two new user equipments according to one embodiment of the present disclosure. [Figure 15] FIG. 15 illustrates a schematic diagram of an example of an allocation of a cyclic shift field in an uplink-related DCI format to n(2) DMRS, λ, and [w(λ)(0) w(λ)(1)] in accordance with one embodiment of the present disclosure. [Figure 16] FIG. 16 illustrates a schematic diagram of an example of multi-transmission time interval (TTI) scheduling, according to one embodiment of the present disclosure. [Figure 17] FIG. 17 illustrates a schematic diagram of another example of multi-TTI scheduling according to another embodiment of the present disclosure. [Figure 18] FIG. 18 illustrates a schematic example of a DMRS transmission based on a staggered pattern, in accordance with one embodiment of the present disclosure. [Figure 19] FIG. 19 illustrates a schematic diagram of a DMRS signal transmitted in four REs for one OCC group according to another embodiment of the present disclosure. [Figure 20] FIG. 20 illustrates a flow chart of a method for receiving a reference signal according to an embodiment of the present disclosure. [Figure 21] FIG. 21 illustrates a block diagram of an apparatus for transmitting a reference signal according to one embodiment of the present disclosure. [Figure 22] FIG. 22 illustrates a block diagram of an apparatus for receiving a reference signal according to an embodiment of the present disclosure. [Diagram 23] FIG. 23 further shows a simplified block diagram of an apparatus 2310 that may be embodied as a UE or included within a UE, and an apparatus 2320 that may be embodied as a base station or included within a base station in a wireless network described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the solutions provided in the present disclosure will be described in detail through embodiments with reference to the accompanying drawings. Note that these embodiments are provided only to enable those skilled in the art to better understand and implement the present disclosure, and do not limit the scope of the present disclosure in any manner.

[0020] In the attached figures, various embodiments of the present disclosure are illustrated in block diagrams, flow charts, and other diagrams. Each block or blocks in the flow charts may represent a module, a program, or a portion of code including one or more executable instructions for performing a specific logical function, and blocks that are not necessarily required in the present disclosure are shown with dashed lines. Also, although the blocks are depicted in a specific sequence for performing steps of a method, in reality, the blocks do not have to be performed in the exact sequence shown. For example, the blocks may be performed in reverse sequence or simultaneously, depending on the nature of the respective operations. It should be noted that each block in the block diagrams and / or flow charts, and combinations thereof, may be realized by a dedicated hardware-based system for performing a specific function / operation, or a combination of dedicated hardware and computer instructions.

[0021] In general, terms used in the claims are to be interpreted according to their ordinary meaning in the art, unless expressly defined otherwise. Reference to "a / an / the / said element, device, component, means, step, etc." is to be openly interpreted as a reference to at least one instance of an element, device, component, means, unit step, etc., without excluding a plurality of such devices, components, means, units, steps, etc., unless expressly stated otherwise. Also, the indefinite article "a / an" as used herein does not exclude a plurality of such steps, units, modules, devices, objects, etc.

[0022] Additionally, in the context of this disclosure, User Equipment (UE) may refer to a terminal, a Mobile Terminal (MT), a Subscriber Station (SS), a Portable Subscriber Station (PSS), a Mobile Station (MS), or an Access Terminal (AT), and may include some or all of the functionality of a UE, a terminal, an MT, a SS, a PSS, an MS, or an AT. Furthermore, in the context of this disclosure, the term "BS" may represent, for example, a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), a Radio Header (RH), a Remote Radio Head (RRH), a relay, or a low power node such as a femto, pico, etc.

[0023] For a better understanding of the present disclosure, first, DMRS patterns and mappings in existing communication systems will be described below with reference to FIG. 2 to FIG.

[0024] First, reference is made to FIG. 2, which illustrates in more detail the DMRS pattern in an existing communication system. In the existing communication system, the physical uplink sharing channel (PUSCH) is based on a Zadoff-Chu sequence. As shown in FIG. 2, for UE i, a signal R i (n) and R' i (n) are the DMRS sequences in the first and second slots, respectively, which may have different cyclic shifts. i (n) and R' i(n) may have the same root sequence if sequence group hopping is disabled. In addition, two users (hereafter referred to as mu-users) transmitting signals with uneven bandwidth in MU-MIMO can use different OCC sequences in the two slots, and multiple mu-users with uniform bandwidth can use different cyclic shifts in DMRS.

[0025] TIFF0007597134000001.tif87165

[0026] TIFF0007597134000002.tif137168

[0027] Up to now, the DMRS patterns and mappings used in existing communication systems have been described, for more details, see for example the relevant contents in 3GPP TS 36.211.

[0028] In addition, as mentioned above, when one or a few DMRS symbols are used in both UL and downlink (DL), more orthogonal ports for partially overlapping BW should be considered to support higher order multi-user MIMO (MU-MIMO). However, in existing communication systems, only two multi-users with uneven bandwidth allocation are supported, or a lot of standard efforts and too large constraints on the length of ZC sequence are required, resulting in Peak to Average Power Ratio (PAPR) problems. Therefore, a new RS pattern and a new RS transmission and reception solution are provided in this disclosure, which are described in more detail with reference to Figures 5 to 23.

[0029] 5 is a schematic diagram illustrating a flow chart of a method for transmitting a reference signal according to an embodiment of the present disclosure. As shown in FIG. 5, first, in step 510, a reference signal configuration indication is received, where a reference signal resource is divided into at least two reference signal groups, and the reference signal configuration indication indicates a reference signal configuration including a reference signal group configuration.

[0030] In an embodiment of the present disclosure, the RS resource, i.e., the basic sequence for the RS, can be divided into M different groups, and the M different groups can be used in either frequency division mode or time division mode to support more users or more layers. Then, examples are given to explain it in more detail, in which the DMRS resource is divided into two groups, i.e., M=2, for ease of understanding. However, those skilled in the art can easily understand that the number of M is not limited to 2, and can be any suitable number.

[0031] In Figure 6A, the DMRS resources are divided into two groups, DMRS group 0 and DMRS group 1, and the REs for carrying DMRS group 0 and the REs for carrying DMRS group 1 are staggered in the frequency domain. Thus, for one DMRS port / layer, the length of the DMRS sequence is the length of the PUSCH or half the length of a legacy DMRS sequence that is not transmitted by the DMRS grouping proposed herein. Thus, the number of resource blocks (RBs) assigned to a new UE using DMRS grouping is a multiple of M (i.e., 2). For example, for M = 2, the number of RBs can be 2, 4, 6, etc. Alternatively, this condition may only need to be met if the number of RBs is less than 6.

[0032] FIG. 6B is a schematic diagram illustrating an example of a DMRS pattern in a frequency division multiplexing mode based on DMRS grouping according to an embodiment of the present disclosure. The difference between the DMRS pattern illustrated in FIG. 6A and the DMRS pattern illustrated in FIG. 6B is that the reference signal groups are hopped to different symbols. In other words, in the DMRS in slot 0 and the DMRS in slot 1, the REs for carrying DMRS group 0 and the REs for carrying DMRS group 1 are staggered in different ways in the frequency domain. In the DMRS symbol in slot 0, the REs for carrying DMRS group 0 and the REs for carrying DMRS group 1 are staggered in the order of DMRS group 0, DMRS group 1, DMRS group 0, DMRS group 1... Meanwhile, in the DMRS symbol in slot 1, the REs for carrying DMRS group 0 and the REs for carrying DMRS group 1 are staggered in the order of DMRS group 1, DMRS group 0, DMRS group 1, DMRS group 0...

[0033] 7 illustrates a further example of a DMRS pattern based on DMRS grouping in a further 5G communication system, in accordance with an embodiment of the present disclosure. As shown in FIG. 7, a novel DMRS pattern is achieved based on DMRS grouping, but in a time division multiplexing mode. That is, in a DMRS symbol in slot 0, all REs carry DMRS group 0, while in a DMRS symbol in slot 1, all REs carry DMRS group 1.

[0034] In practice, in future 5G communication systems, the frame structure may have another form. In future 5G communication systems, the TTI length may be very short, and therefore, one slot may contain two or four consecutive DMRS symbols, as shown in Figures 8A to 8E. In addition, as shown in Figure 8F, M is not limited to 2, but may be 3 or more.

[0035] Whether the legacy DMRS pattern or the new DMRS pattern is used, or in other words, whether the DMRS group configuration is valid or not, can be signaled by DMRS configuration indication (DCI) format information or a bit of radio resource control (RRC) signaling. The DMRS group configuration for different UEs or different layers of a UE can be indicated by RS signal indication, which can be explicit or implicit RRC signaling or DCI format information. That is, the DMRS group configuration can be indicated by new RRC signaling or can be indicated by a DCI format that also indicates the cyclic shift configuration and the orthogonal cover code configuration. As an example, the reference signal group configuration can be implicitly indicated by the cyclic shift configuration. As another example, the reference signal group configuration can be explicitly indicated by a bit of the reference signal configuration indication.

[0036] Additionally, the RRC signaling for DMRS group configuration can be separate from the RRC signaling for indicating whether the new DMRS pattern is valid, or alternatively, whether the new DMRS pattern is valid and the DMRS group configuration can be indicated in the same RRC signaling. Furthermore, the same or different bits in the DCI format information can be used to provide the DMRS group indication and an indication of whether the new DMRS is valid.

[0037] In one embodiment of the present disclosure, only one reference group can be used by one UE. In such a case, the DMRS group configuration can be implicitly indicated by the cyclic shift configuration, i.e., the cyclic shift field in the DCI format. For example, in FIG. 9, a part of the index in the CS field of the DCI format is for the new DMRS pattern, and the remaining part of the index in the CS field of the DCI format is for the legacy DMRS pattern. In other words, in the table for the CS field in the DCI for the new UE, every index is divided into two parts, the first part is for indicating the UE to use the legacy DMRS pattern, and the second part is for indicating the UE to use the new DMRS pattern. In the second part, the index is further divided into two parts, one for DMRS group 0 and another for DMRS group 1 (when M=2). For example, as shown in FIG. 9, if the index in the DCI format is 000, the UE should transmit DMRS using the new DMRS group 0 of the new DMRS pattern. On the other hand, if the index in the DCI format is 010, the UE should use the legacy DMRS pattern. In such a case, no RRC signaling or DCI information bits are needed to indicate to the new UE whether the legacy pattern or the new pattern is to be used.

[0038] FIG. 10 illustrates a schematic diagram of an indication scheme for indicating a DMRS group configuration according to another embodiment of the present disclosure, in which an index in the CS field of a DCI format is divided into M parts (M=2). As illustrated in FIG. 10, an index in the CS field of a DCI format is divided into two parts, one for DMRS group 0 and another for DMRS group 1. For example, indexes 000, 001, 010, and 111 are included in the first group, i.e., DMRS group 0, and indexes 011, 100, 101, and 110 are included in the second group, i.e., DMRS group 1. Alternatively, a cyclic shift (i.e., n 1 shown in FIG. 3) may be used to indicate the DMRS group configuration. (1) DMRS The DMRS group IDs (values) may also be divided into M groups based on RRC signaling. As an example, indexes 0, 1, 2, and 3 correspond to DMRS group 0, and the remaining indexes correspond to DMRS group 1. In such a case, 1-bit RRC signaling or 1-bit DCI information may be used to indicate whether a legacy pattern or a new pattern is used.

[0039] In another embodiment of the present disclosure, more than one reference signal group is allowed to be used by one user equipment. In that case, DMRS sequences for different layers of one UE can be multiplexed into different DMRS groups and a new mapping table can be used, which can be signaled by RRC signaling or one bit in the DCI format. An example of the new table is shown in Figure 11, where Δ TC indicates the DMRS group configuration, where a value of 0 indicates DMRS group 0 and a value of 1 indicates DMRS group 1. From Figure 11, it is clear that the DMRS group configuration is tied to the CS index and layer. In such a case, four UEs with two layers each can be scheduled in the following manner, where fields 000+001+010+011 are used and multiplexing is implemented by intra-UE CS, inter-UE OCC, and FDM.

[0040] If different layers in one UE can be multiplexed into different DMRS groups, two layers can be supported with OCC or FDM, e.g., field 100 or 101 with FDM and field 110 or 111 with OCC. At the same time, up to eight layers can be supported in single user (SU) mode. In this case, the UE needs to be configured with the layer numbers, so that the UE can be implicitly informed of DMRS, OCC, and FDM. As an example, if the UE is configured with eight layers and the field is 000, the UE can set the predefined mapping to CS, OCC, and Δ for layers 0-3. TC As shown in the table, for layers 4-7, CS and OCC are the same as for layers 0-3, but for FDM configuration (1-Δ TC ) can be assumed.

[0041] In a further embodiment, for SU-MIMO with four or more layers, the CS, OCC, and DMRS group configurations can be implicitly signaled to the UE. In such a case, an aggregated reference signal configuration can be used to support more layers in DMRS transmission. The aggregated reference signal configuration indicates a reference signal configuration aggregated from more than one configuration. For example, the aggregated reference configuration can be formed by aggregating the reference signal configuration indicated by the reference signal configuration indication and another reference signal configuration predefined to be used therewith. The other reference signal configuration can be a configuration obtained from a reference signal configuration indicated by the reference signal configuration indication but having a different reference signal group configuration. Or, alternatively, the other reference signal configuration can be a reference signal configuration in a cyclic field mapping table, which is different from the reference signal configuration indicated by the reference signal configuration indication and is predefined to be used with the reference signal configuration indicated by the reference signal configuration indication. For example, for a layer number v, the first v / 2 layer and the next v / 2 layer can use the same CS / OCC but for different DMRS group configurations. Therefore, in this embodiment, even if the reference signal indication indicates only one reference signal configuration, two or more CS / OCC / DMRS group configurations are aggregated to support more layers (up to 8 layers when M=2).

[0042] As an example, in the legacy table shown in Figure 4, two indexes (i.e., two configurations) of the CS field are configured so that one UE indicates the SC and OCC configurations for eight layers. The relationship between the two indexes can be fixed or predefined and signaled to the UE by using the legacy CS field of the DCI format. For example, for eight layers, index 000 actually represents indexes 000 and 001 indicating CS / OCC for the first four layers and the next four layers, respectively, layers 0, 1, 2, and 3 use CS: 0, 6, 3, and 9, and OCC:

[0011] ,

[0011] [1 -1], [1-1], and layers 4, 5, 6, and 7 use CS: 6, 0, 9, and 3, and OCC: [1 -1], [1 -1],

[0011]

[0011] . Or, alternatively, index 000 can be used to indicate CS / OCC for even layers, e.g., 0, 2, 4, 6, and index 001 can be used to indicate CS / OCC for odd layers, e.g., 1, 3, 5, 7.

[0043] Then, returning to FIG. 5, as can be seen there, in step 520, a reference signal is transmitted using a reference signal sequence in the reference signal group shown in the reference signal group configuration, where the reference signal sequence can be multiplexed with different layers or different users in different reference signal groups.

[0044] After receiving the reference signal configuration information, the UE may transmit the DMRS sequence according to the configuration indicated in the reference signal configuration information.

[0045] Considering four one-layer UEs as an example, UE0, UE1, UE2, and UE3 are configured with indices 000, 001, 100, and 101, respectively, in the DCI format. Figure 12 shows the CS configuration, OCC configuration, and DMRS signal transmitted in slot 0 or slot 1 when four new UEs are paired. In the current standard, when sequence group hopping is disabled, the cyclic shift offset between R'i and Ri should be the same for all those UEs to support MU-MIMO, i.e., R'i(n)=e jan Ri(n). In other words, for all mu-users, the cyclic shift index offset (or modulus by 12) between two slots is the same. For example, for UE0, the cyclic shift indexes of slots 0 and 1 are 0 and 6, respectively, and the index offset value is 6. For UE3, the indices of the two slots are 8 and 2, respectively, and the offset after modulus by 12 is 6.

[0046] 13 shows reference signals transmitted in two slots by two UEs using the new DMRS format, where the first two reference signals in the four nearest REs, i.e., slot 0 and slot 1, are also shown at the bottom for clarity. The symbols in the four nearest REs are given by [ R0(n) e jan R0(n) 0 0 ] [ R1(n) -e jan R1(n) 0 0 ] [ 0 0 R2(n) e jan R2(n)] [ 0 0 R3(n) -e jan R3(n)]

[0047] From the above equation, it can be seen that for two new UEs, orthogonality is achieved among these four REs even though they have unequal bandwidths.

[0048] However, when a legacy UE is paired with a new UE, they use different DMRS patterns and the legacy UE is not multiplexed into a different DMRS group, so orthogonality cannot be achieved. In other words, for the same frequency resource, the length of the legacy DMRS sequence is twice the length of the new DMRS sequence. Therefore, when the starting frequency position of the legacy UE and the new UE is the same, the resource index of the legacy DMRS sequence is basically twice that of the new DMRS sequence. Figure 14 shows an example of a CS configuration, an OCC configuration, and a DMRS signal transmitted in slot 0 and slot 1 when a legacy UE is paired with a new UE. The nearest four REs are given by: [ R0(2n) e ja2n R0(2n) R0(2n+1) e ja(2n+1) R0(2n+1) [ R1(n) -e jan R1(n) 0 0 ] [ 0 0 R2(n) -e jan R2(n)

[0049] From the above formula, it is clear that orthogonality cannot be achieved. In fact, to achieve orthogonality, the cyclic shift offset between two slots for the new UE should be twice that of the legacy UE. In other words, except for the OCC sequence, the phase shift of the two slots should be kept the same as that of the legacy in the same frequency resource n, that is, R'1 / R1=R'0 / R0. Therefore, in such a case, in order to improve the orthogonality between the new user equipment and the legacy user equipment, it is required to increase the cyclic shift offset between slots for the new user equipment transmitting the reference signal.

[0050] In one embodiment of the present disclosure, when the DMRS sequence is generated, the cyclic shift is expanded by M. For example, for DMRS group 0, the reference signal sequence is modified as follows:

number

number

[0051] After the DMRS sequence is modified as proposed, the new symbols in the nearest four REs are given by: [ R0(2n) e ja2n R0(2n) R0(2n+1) e ja(2n+1) R0 (2n+1) [ R1(n) -e ja2n R1(n)00] [ 0 0 R2(n) -e ja(2n+1) R2(n) ]

[0052] From the above equation, it can be seen that orthogonality can be obtained between the legacy UEs and the new UEs.

[0053] However, it can be seen that in the new DMRS sequence, the orthogonality between different CSs is broken. For example, the orthogonality between CS0 and CS6 is broken. In the existing DMRS configuration, the cyclic shift offset is 6, and two REs that are closest in frequency domain can be one orthogonal group in the legacy pattern, i.e., they can be transformed into an orthogonal frequency code that spans a block of two consecutive subcarriers in the frequency domain. As a result, the granularity of the channel estimation is (approximately) one per two subcarriers. After the cyclic shift offset is increased when the DMRS sequence is generated, this is not guaranteed.

[0054] In an embodiment with increased cyclic shift offset, the orthogonality of a CS offset of 3 results in orthogonal frequency codes spanning two consecutive blocks of DMRS subcarriers. In addition, two CSs with an offset of 6 results in the same DMRS sequence.

number

number

number

[0055] As an example, one-bit DCI information or RRC signaling may be used to indicate whether a new DMRS pattern / sequence or a legacy DMRS pattern / sequence is used. For the new one, the CS offset between the second layer and the first layer is 3. The CS offset is scaled by a factor M, so that the associated DMRS sequences derived from indexes 000 and 001 are the same, the associated DMRS sequences derived from indexes 010 and 111 are the same, the associated DMRS sequences derived from indexes 011 and 110 are the same, and the associated DMRS sequences derived from indexes 100 and 101 are the same. Thus, the total CS index may be divided into two groups, one group corresponding to one DMRS group and having different associated DMRS sequences. For example, indexes 000, 010, 011, 100, 101 may correspond to DMRS group 0, and the remaining indexes may correspond to DMRS group 1. In this way, when a UE receives index 000, it means that the UE belongs to DMRS group 0.

[0056] In addition, considering backward compatibility, the phase shift between two slots in one subframe for the new UE should be kept the same as that of the legacy one.

[0057] For DMRS Group 0, the reference signal sequence may remain the same as the legacy formula below.

number

number

[0058] Therefore, in this solution, the cyclic shift offset between two slots in one subframe for the new UE is kept M times that of the legacy one.

[0059] In addition, it can be seen that in further 5G communication systems, the TTI is very short. In a scenario with a very short TTI length, the DMRS can be removed in some TTIs. In other words, the DMRS is not transmitted in all TTIs. In this case, one or several bits in the physical control signaling can be used to inform the UE how many DMRS symbols are used or whether there is a DMRS symbol in the current TTI. If there is no DMRS in the TTI, the UE can demodulate the data using the previous DMRS. In addition, a retransmission without DMRS can be implemented by using the DMRS in the previous transmission or the initial transmission.

[0060] In addition, multiple TTI scheduling can be considered. In other words, the eNB only configures the control signaling information in one TTI, and the UE can receive and / or transmit data in multiple TTIs based on the control signaling information. Therefore, in such a case, one or a few TTIs can include DMRS. As another option, an OCC sequence of length L can be used, which is shown in FIG. 16. As shown, an OCC sequence or a DFT sequence of length L can be applied in the DMRS for those L TTIs. In this case, there is only one DMRS in each TTI. Considering L=4 as an example, four orthogonal OCC sequences can be multiplexed into the DMRS sequence. In this way, up to four layers or four mu-users can be multiplexed with the OCC sequence.

[0061] As a further option, six DFT sequences can also be used, as shown in Figure 17. In such a case, two DMRS sequences can be transmitted in each TTI, and the DFT sequence values ​​can be multiplexed into the DMRS sequences in each TTI. Thus, up to six layers or users can be multiplexed with six DFT sequences.

[0062] In another different embodiment, each user or layer can be transmitted by using M DMRS groups in a staggered pattern. In other words, one UE transmits multiplexed DMRS sequences based on a staggered pattern with M DMRS groups. In this embodiment, the UE needs to transmit DMRS sequences in each DMRS group for all layers. In such a case, different UEs can be multiplexed with different OCC sequences.

[0063] For example, as shown in FIG. 18, when only one symbol is used for DMRS transmission, both UE0 and UE1 transmit reference signal sequences in an alternating pattern using M DMRS groups, and the two UEs transmit reference signals in MU-MIMO mode with OCC=2 in the same one symbol, where [W 00 W 01 ]=

[0011] and [W 10 W 11 In such a case, UE0 with one layer receives the DMRS sequence W 00 ×R0 in DMRS group 0, and DMRS sequence W 01 ×R′0 in DMRS group 1, while in the same symbol, UE1 transmits DMRS sequence W 10 ×R1 is transmitted in DMRS group 0, and DMRS sequence W 1119, in another case where two symbols are used for DMRS transmission, for example in the R10 uplink DMRS pattern, different CS, R 0 i,R 1 i,R 2 i,R 3 Four ZC sequences with i can be used, thus extending the R10 uplink MU-MIMO mechanism with OCC=4 to support four MU users, and the UEs can be scheduled on different bandwidths. In such a case, the OCC can be: [w i0 w i1 w i2 w i3 ] = [1 1 1 1], or [1 -1 1 -1], or [1 1 -1 -1], or [1 -1 -1 1]

[0064] Note that in an embodiment where each user or layer can transmit in a staggered pattern using M DMRS groups, the DMRS sequences can be modified to be backward compatible to preserve orthogonality between new and legacy UEs and between different CSs, as described above. In other words, for all UEs, the cyclic shift offsets between the four ZC sequences should be kept the same. In particular, for UEi, R 1 i and R 2 i The cyclic shift offset between and for UEj scheduled with UEi in one TTI is 1 j and R 2 j On the other hand, if a new UE is multiplexed with a legacy UE, the cyclic shift offset between the DMRS sequences of the two slots should also be the same as that of the legacy.

[0065] In addition, further schemes can be used to improve transmission performance. For example, when DMRS group is enabled, if the power of DMRS symbol and the power of PUSCH symbol are kept the same in one TTI, the power in one DMRS RE is twice that in PUSCH. Furthermore, if the power of one DMRS RE and the power of one PUSCH are kept the same, the power of DMRS symbol is half that of PUSCH symbol. These imply power imbalance between different symbols. Therefore, the scaling factor can be changed to avoid power imbalance.

[0066] Therefore, in section 5.5.2.1.2 of 3GPP TS 36.213, the amplitude magnification is defined as delta × β PUSCH where delta is 1 or √2 and can be signaled to the UE as default information. As an example, for a UE with a new DMRS pattern, the amplitude scaling factor can be delta×β PUSCH Alternatively, the eNB can inform the UE of the value of delta using RRC signaling, and the eNB can select one value from multiple values ​​for the UE. For example, the candidate values ​​of delta can be {1, √2}, or {1, √2, √0.5, etc.}. In that way, the power imbalance can be greatly mitigated.

[0067] So far, the description has been mainly given to the solution of reference signal transmission. In the present disclosure, a method of receiving a reference signal is also provided, which is described with reference to FIG.

[0068] 20, method 2000 may start at step 2010, where a reference signal configuration indication is transmitted. In particular, as discussed above, the reference signal resources are divided into at least two reference signal groups, and the reference signal configuration indication may indicate a reference signal configuration including a reference signal group configuration.

[0069] In one embodiment of the present disclosure, the reference signal resource is divided into at least two reference signal groups, and the at least two reference signal groups are multiplexed in either a frequency division multiplexing mode or a time division multiplexing mode, so that more users or more layers can be supported with limited antenna port resources. In addition, in the frequency division multiplexing mode, the at least two reference signal groups can further be hopped in different symbols.

[0070] In another embodiment of the present disclosure, the reference signal configuration indication may further indicate a cyclic shift configuration and an orthogonal cover code configuration in addition to the reference signal group configuration. This means that the cyclic shift configuration, the orthogonal cover code configuration, and the reference signal group configuration can be indicated by the same reference signal indication, i.e., DCI format. For example, the reference signal group configuration may be implicitly indicated by the cyclic shift configuration, or alternatively may be explicitly indicated by a bit in the reference signal configuration indication. In addition, it may be indicated whether the reference signal group configuration is valid by a bit in the reference signal configuration indication or by using separate RRC signaling.

[0071] In some embodiments of the present disclosure, only one reference signal group is permitted to be used by one user equipment. In such a case, a portion of the indexes for the cyclic shift configuration is reserved for the legacy reference signal pattern, and the remaining portion of the indexes is divided into at least two groups, and each of the divided indexes is assigned to a corresponding one of the at least two reference signal groups. Alternatively, the indexes for the cyclic shift configuration can be divided into at least two groups, and each of the divided indexes is assigned to a corresponding one of the at least two reference signal groups.

[0072] In some embodiments of the present disclosure, more than one reference signal group is permitted to be used by one user equipment. In such a case, the reference signal group indication can be tied to an index for a cyclic shift. In other words, for a particular index for a cyclic shift, the reference signal group indication is predefined.

[0073] Then, as shown in step 2020 of FIG. 20, a reference signal is received and the reference signal is transmitted by using a reference signal sequence in a reference signal group indicated by the reference signal group configuration, where the reference signal sequence can be multiplexed with different layers or different users in different reference signal groups.

[0074] After the reference signal configuration indication is sent to the UE, the UE transmits a reference signal using a reference signal sequence in the reference signal group indicated by the reference signal group configuration. The eNB can receive reference signals from the UE, and the reference signal sequence can be multiplexed with different layers or different users in different reference signal groups.

[0075] In addition, the reference signal may be transmitted using an aggregated reference signal configuration to support more layers. The aggregated reference signal configuration may be a reference signal configuration aggregated from more than one configuration, and the aggregated reference signal configuration may be formed by aggregating a reference signal configuration indicated by the reference signal configuration indication and another reference signal configuration predefined to be used with the reference signal configuration. The other reference signal configuration may be a reference signal configuration obtained from a reference signal configuration indicated by the reference signal configuration indication configuration but having a different reference signal group configuration, or may be a different reference signal configuration in a cyclic field mapping table predefined to be used with the reference signal configuration indicated by the reference signal configuration indication.

[0076] The eNB demodulates the reference signal according to the reference signal configuration transmitted to the UE and learns the channel condition.

[0077] In an embodiment of the present disclosure, a new solution for transmitting and receiving reference signals is provided, in which reference signal resources are divided into at least two reference signal groups, and reference signals for different layers or users can be multiplexed into different reference signal groups. Thus, more mu-users with non-uniform bandwidths can be supported without significant channel estimation loss and PAPR loss.

[0078] In addition, FIG. 21 illustrates a block diagram of an apparatus for transmitting a reference signal according to an embodiment of the present disclosure.

[0079] As shown in Fig. 21, the apparatus 2100 includes an indication receiving module 2110 and a signal transmitting module 2120. The indication receiving module 2110 may be configured to receive a reference signal configuration indication, where a reference signal resource is divided into at least two reference signal groups, and the reference signal configuration indication indicates a reference signal configuration including a reference signal group configuration. The signal transmitting module may be configured to transmit a reference signal using a reference signal sequence in a reference signal group indicated by the reference signal group configuration, and the reference signal sequence can be multiplexed with different layers or different users of different reference signal groups.

[0080] In one embodiment of the present disclosure, the at least two reference signal groups can be multiplexed in either a frequency division multiplexing mode or a time division multiplexing mode, in which the at least two reference signal groups can be further hopped to different symbols.

[0081] In another embodiment of the present disclosure, the reference signal configuration may further indicate a cyclic shift configuration and an orthogonal cover code configuration. In this case, the reference signal group configuration may be implicitly indicated by the cyclic shift configuration or may be explicitly indicated by a bit in the reference signal configuration indication. In addition, whether the reference signal group configuration is valid may be indicated by a separate RRC signaling, but may also be indicated by a bit in the reference signal configuration indication.

[0082] In a further embodiment of the present disclosure, only one reference signal group may be permitted to be used by a user. In such a case, a portion of the indexes of the cyclic shift configuration may be reserved for legacy reference signal patterns, and the remaining portion of the indexes may be divided into at least two groups, with each group being assigned to a corresponding one of the at least two reference signal groups. Or, alternatively, the indexes for the cyclic shift configuration may be divided into at least two groups, with each group being assigned to a corresponding one of the at least two reference signal section loops.

[0083] In further embodiments of the present disclosure, more than one reference signal group can be used by a user.

[0084] In a further embodiment of the present disclosure, the reference signal can be transmitted using an aggregated reference signal configuration to support more layers, the aggregated reference signal configuration being formed by aggregating the reference signal configuration indicated by the reference signal configuration indication with another reference configuration predefined to be used with the reference signal configuration, in which case the other reference signal configuration may be a reference signal configuration indicated by the reference signal configuration indication but obtained from a reference signal configuration of a different reference signal group configuration, or alternatively, the other reference signal configuration may be a different reference signal configuration in a cyclic field mapping table predefined to be used with the reference signal configuration indicated by the reference signal configuration indication.

[0085] Additionally, to improve orthogonality between the new user equipment and the legacy user equipment, the apparatus 2100 may further include an offset increasing module 2130 configured to increase a cyclic shift offset between slots for the new user equipment transmitting the reference signal. Additionally, to maintain orthogonality between different cyclic shifts, the apparatus 2100 may further include a shift decreasing module 2140 configured to decrease the cyclic shift for the new user equipment to maintain orthogonality between different cyclic shifts.

[0086] FIG. 22 further illustrates an apparatus for receiving a reference signal according to an embodiment of the present disclosure. As shown in FIG. 22, the apparatus 2200 may include an indication sending module 2210 and a signal receiving module 2220. The indication sending module 2210 may be configured to send a reference signal configuration indication, where a reference signal resource is divided into at least two reference signal groups, and the reference signal configuration indication indicates a reference signal configuration including a reference signal group configuration. The signal receiving module 2220 may be configured to receive a reference signal transmitted using a reference signal sequence in a reference signal group indicated by the reference signal group configuration, and the reference signal sequence may be multiplexed with different layers or different users of different reference signal groups.

[0087] In one embodiment of the present disclosure, the at least two reference signal groups can be multiplexed in either a frequency division multiplexing mode or a time division multiplexing mode, in which the at least two reference signal groups can be further hopped to different symbols.

[0088] In another embodiment of the present disclosure, the reference signal configuration may further indicate a cyclic shift configuration and an orthogonal cover code configuration. In this case, the reference signal group configuration may be implicitly indicated by the cyclic shift configuration or may be explicitly indicated by a bit in the reference signal configuration indication. In addition, whether the reference signal group configuration is valid may be indicated by a separate RRC signaling, but may also be indicated by a bit in the reference signal configuration indication.

[0089] In a further embodiment of the present disclosure, only one reference signal group may be permitted to be used by a user. In such a case, a portion of the indexes of the cyclic shift configuration may be reserved for legacy reference signal patterns, and the remaining portion of the indexes may be divided into at least two groups, with each group being assigned to a corresponding one of the at least two reference signal groups. Or, alternatively, the indexes for the cyclic shift configuration may be divided into at least two groups, with each group being assigned to a corresponding one of the at least two reference signal section loops.

[0090] In further embodiments of the present disclosure, more than one reference signal group can be used by a user.

[0091] In a further embodiment of the present disclosure, the reference signal can be transmitted using an aggregated reference signal configuration to support more layers, the aggregated reference signal configuration being formed by aggregating the reference signal configuration indicated by the reference signal configuration indication with another reference configuration predefined to be used with the reference signal configuration, in which case the other reference signal configuration may be a reference signal configuration indicated by the reference signal configuration indication but obtained from a reference signal configuration of a different reference signal group configuration, or alternatively, the other reference signal configuration may be a different reference signal configuration in a cyclic field mapping table predefined to be used with the reference signal configuration indicated by the reference signal configuration indication.

[0092] Up to this point, the devices 2100 and 2200 have been briefly described with reference to Figures 21 and 22. It should be noted that the devices 2100 and 2200 may be configured to implement similar functions to those described with reference to Figures 5 to 20. Therefore, for details on the operation of the modules in these devices, reference may be made to the descriptions made with reference to Figures 5 to 20 regarding the respective steps of the method.

[0093] Furthermore, the components of the apparatuses 2100 and 2200 may be embodied in hardware, software, firmware, and / or any combination thereof. For example, the components of the apparatuses 2100 and 2200 may be implemented by a circuit, a processor, or any other suitable selection device, respectively. Those skilled in the art will appreciate that the above examples are for illustration only and not for limitation. For example, the number M of DMRS groups is not limited to 2, even if it is taken as an example to illustrate the present disclosure. In addition, the reference signal reception and transmission solution is not limited to only UL transmission, but can also be used in DL transmission. However, in such a case, unlike the operation described above, the eNB transmits both the reference signal configuration indication and the reference signal, instead of transmitting the reference signal configuration indication and receiving the reference signal. Meanwhile, the UE receives the RS configuration indication and the reference signal, instead of transmitting the reference signal, receives the RS configuration indication and the reference signal, and demodulates the reference signal based on the RS configuration indicated in the RS configuration indication.

[0094] Additionally, in some embodiments of the present disclosure, the devices 2100 and 2200 may each have at least one processor. The at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors, already known or developed in the future. The devices 2100 and 2200 may each have at least one memory. The at least one memory may include, for example, semiconductor memory devices, such as RAM, ROM, EPROM, EEPROM, and flash memory devices. The at least one memory may be used to store a program of computer-executable instructions. The program may be written in any high-level and / or low-level compilable or interpretable programming language. According to an embodiment, the computer-executable instructions, together with the at least one processor, may be configured to cause the devices 2100 and 2200 to perform at least the operations according to the methods as discussed with reference to FIG. 5 through FIG. 20, respectively.

[0095] FIG. 23 further shows a simplified block diagram of an apparatus 2310 that may be embodied as or included within a terminal device, such as a UE for a wireless network in a wireless network, and an apparatus 2320 that may be embodied as or included within a base station, such as a NB or eNB, as described herein.

[0096] The device 2310 comprises at least one processor 2311, such as a data processor (DP), and at least one memory (MEM) 2312 coupled to the processor 2311. The device 2310 may further comprise a transceiver (TX / RX) 2313 coupled to the processor 2311, which may be operable to communicatively connect to the device 2320. The MEM 2312 stores a program (PROG) 2314. The PROG 2314 may include instructions that, when executed on the associated processor 2311, enable the device 2310 to operate according to embodiments of the present disclosure, for example to perform the method 500. The combination of the at least one processor 2311 and the at least one MEM 2312 may form a processing means 2315 suitable for implementing various embodiments of the present disclosure.

[0097] The device 2320 comprises at least one processor 2321, such as a DP, and at least one MEM 2322 coupled to the processor 2321. The device 2320 may further comprise a suitable TX / RX 2323 coupled to the processor 2321, which may be operable for wireless communication with the device 2310. The MEM 2322 stores PROG 2324. The PROG 2324 may include instructions that, when executed on the associated processor 2321, enable the device 2320 to operate according to an embodiment of the present disclosure, for example to execute the method 2000. The combination of the at least one processor 2321 and the at least one MEM 2322 may form a processing means 2325 suitable for implementing various embodiments of the present disclosure.

[0098] Various embodiments of the present disclosure may be implemented by a program executed by one or more processors 2311, 2321, software, firmware, hardware, or a combination thereof.

[0099] MEMs 2312 and 2322 may be of any type suitable for the local technology environment and may be implemented using any suitable data storage technology, such as, by way of non-limiting example, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

[0100] Processors 2311 and 2321 may be of any type suitable for the local technology environment and may include, by way of non-limiting examples, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor DPS, and a processor based on a multi-core processor architecture.

[0101] In addition, the present disclosure may also provide a carrier comprising the above-mentioned computer program, the carrier being one of an electrical signal, an optical signal, a radio signal, or a computer-readable medium. The computer-readable medium may be, for example, a random access memory (RAM), a read only memory (ROM), a flash memory, a magnetic tape, an optical compact disc such as a CD-ROM, a DVD, and a Blue-ray disc, or an electronic memory device.

[0102] The techniques described herein may be implemented by various means, and an apparatus performing one or more functions of a corresponding apparatus described in an embodiment may have means for performing one or more functions of the corresponding apparatus described in an embodiment as well as conventional means, which may have separate means for separate functions, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. For firmware or software, the implementation may be through modules (e.g., procedures, functions, etc.) that perform the functions described herein.

[0103] The embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatus. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute on the computer or other programmable data processing apparatus, produce means for performing the functions specified in the flowchart blocks.

[0104] Although the present specification contains many specific implementation details, these should not be construed as limitations on the scope of the implementation or scope that may be claimed, but rather as descriptions of features that may be specific to certain embodiments of a particular example. Certain features described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, even if features are described above as acting in a particular combination and initially claimed as such, one or more features from a claimed combination may in some cases be cut out of the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0105] It will be obvious to those skilled in the art that as technology advances, the concept of the present invention can be implemented in various ways. The above-mentioned embodiments are given to illustrate, not to limit, the present disclosure, and it will be understood that modifications and variations are possible without departing from the spirit and scope of the present disclosure, as those skilled in the art will easily understand. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The scope of protection of the present disclosure is defined by the appended claims.

Claims

1. A user equipment (UE), means for receiving downlink control information from a base station; means for determining, based on the downlink control information, that a value of a cyclic shift field of the downlink control information corresponds to either a first reference signal sequence or a second reference signal sequence; means for generating one of the first reference signal sequence or the second reference signal sequence, the one to which the value of the cyclic shift field corresponds; The first reference signal sequence is a base sequence By the cyclic shift α of is defined as The second reference signal sequence is a base sequence By the cyclic shift α of is defined as User equipment.

2. means for transmitting a reference signal to the base station based on the one of the first reference signal sequence or the second reference signal sequence. The user equipment of claim 1 .

3. The downlink control information is received in a DCI (Downlink Control Information) format. The user equipment of claim 1 .

4. The cyclic shift field is received in a Downlink Control Information (DCI) format. The user equipment of claim 1 .

5. the value of the cyclic shift field corresponding to the first reference signal sequence is one of 011, 100, 101, and 110; the value of the cyclic shift field corresponding to the second reference signal sequence is one of 000, 001, 010, and 111. The user equipment of claim 1 .

6. a first resource for transmission of the first reference signal sequence corresponds to even-numbered subcarriers and a second resource for transmission of the second reference signal sequence corresponds to odd-numbered subcarriers. The user equipment of claim 1 .

7. Slot n ｓ a cyclic shift α for at least one of the first reference signal sequence and the second reference signal sequence associated with layer λ in λ teeth, Using α λ = 2πn ＣＳ，λ / 12, The user equipment of claim 1 .

8. a length of at least one of the first and second reference signal sequences is half a length of a legacy Demodulation Reference Signal (DMRS) sequence; The user equipment of claim 1 .

9. The length of each of the first and second reference signal sequences is and is the resource block size in the frequency domain expressed as the number of subcarriers, and Let us assume the maximum uplink bandwidth configuration. That is, The user equipment of claim 1 .

10. A base station, A means for transmitting downlink control information to a user equipment (UE), determining, by the user equipment based on the downlink control information, that a value of a cyclic shift field of the downlink control information corresponds to either a first reference signal sequence or a second reference signal sequence; The base station further comprises means for receiving a reference signal corresponding to a corresponding one of the first reference signal sequence or the second reference signal sequence having a corresponding value of the cyclic shift field; The first reference signal sequence is a base sequence By the cyclic shift α of is defined as The second reference signal sequence is a base sequence By the cyclic shift α of is defined as Base station.

11. The downlink control information is transmitted in a DCI (Downlink Control Information) format. The base station according to claim 10.

12. The cyclic shift field is transmitted in a DCI (Downlink Control Information) format. The base station according to claim 10.

13. the value of the cyclic shift field corresponding to the first reference signal sequence is one of 011, 100, 101, and 110; the value of the cyclic shift field corresponding to the second reference signal sequence is one of 000, 001, 010, and 111. The base station according to claim 10.

14. a first resource for transmission of the first reference signal sequence corresponds to even-numbered subcarriers and a second resource for transmission of the second reference signal sequence corresponds to odd-numbered subcarriers. The base station according to claim 10.

15. Slot n ｓ a cyclic shift α for at least one of the first reference signal sequence and the second reference signal sequence associated with layer λ in λ teeth, Using α λ = 2πn ＣＳ，λ / 12, The base station according to claim 10.

16. a length of at least one of the first and second reference signal sequences is half a length of a legacy Demodulation Reference Signal (DMRS) sequence; The base station according to claim 10.

17. The length of each of the first and second reference signal sequences is and is the resource block size in the frequency domain expressed as the number of subcarriers, and Let us assume the maximum uplink bandwidth configuration. That is, The base station according to claim 10.

18. 1. A method implemented by a User Equipment (UE), comprising: receiving downlink control information from a base station; determining, based on the downlink control information, that a value of a cyclic shift field of the downlink control information corresponds to either a first reference signal sequence or a second reference signal sequence; generating one of the first reference signal sequence or the second reference signal sequence, the one having a corresponding value of the cyclic shift field; The first reference signal sequence is a base sequence By the cyclic shift α of is defined as The second reference signal sequence is a base sequence By the cyclic shift α of is defined as method.

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