Method for transmitting and / or receiving multi-carrier radio signals

Abstract

The present invention is a communication method implemented in a device - to - device communication system for transmitting and / or receiving multi - carrier radio signals. This communication method uses a resource pool for this transmission and / or reception. The resource pool is divided in time domain by time intervals. Each time interval includes X multi - carrier symbols with respect to a first sub - carrier spacing SCS1. At least a part of the X multi - carrier symbols can be used for data transmission in each time interval. The resource pool is divided in frequency domain into L1 sub - channels with respect to the first sub - carrier spacing SCS1. The resource pool includes a set of N1×L1 time - frequency units. Each set spans N1 time intervals and L1 sub - channels with respect to the first sub - carrier spacing SCS1. Each set is associated with a feedback opportunity and is included within P multi - carrier symbols with respect to the first sub - carrier spacing SCS1 that are not available for data transmission in the time domain with respect to the first sub - carrier spacing SCS1. The feedback opportunity includes at least one, up to R max multi - carrier symbols with respect to a second sub - carrier spacing SCS2 that can be used for feedback transmission, where SCS2 = k1×SCS1 and k1>1, and R max = k1×P - 2. The feedback opportunity starts at least after the end of a first guard time guard1 after the multi - carrier symbols available for data transmission with respect to the first sub - carrier spacing SCS1 and ends at least before a second guard time guard2 before the start time of another multi - carrier symbol available for data transmission with respect to the first sub - carrier spacing SCS1. The method is concerned with this.

Description

Technical Field

[0001] The present disclosure relates to the field of telecommunication.

[0002] More specifically, the present disclosure relates to a communication method, an inter-device communication system, a computer program, and a user equipment.

Background Art

[0003] In the future, inter-device communication will shift from LTE (Long Term Evolution) side link to NR (New Radio) side link. To ensure smooth technology migration, currently 3GPP (trademark) defines LTE / NR coexistence on the same channel between two RATs (Radio Access Technologies). The main use case is the coexistence of LTE / NR-V2X in the ITS (Intelligent Transport System) band. The resource pools for LTE and NR side link communications may partially or entirely overlap. LTE terminals do not recognize the presence of NR traffic. There may also be no network deployment (out of coverage). In the case of coexistence, the transmissions of LTE V2X and NR V2X are synchronized in time and frequency.

[0004] Currently, the LTE V2X (Vehicle-to-Everything) system uses a fixed sub-carrier spacing of 15 kHz and is not capable of receiving HARQ (Hybrid Automatic Repeat reQuest) feedback.

[0005] Furthermore, even when there is no LTE V2X traffic (e.g., in a resource pool reserved for NR V2X dedicated transmission), currently, the resource pool only allows one sub-carrier spacing, and different sub-carrier spacings are more suitable for different services or QoS requirements, so there is a lack of flexibility.

[0006] FIG. 1 shows one of the typical slot structures for LTE V2X transmission and / or reception. The resource pool can be considered to be divided in terms of a time interval (e.g., a slot) and a frequency interval (e.g., a subchannel). FIG. 1 represents a time-frequency unit 100 for LTE V2X transmission and / or reception that spans one time interval in the time domain and one subchannel in the frequency domain. In the time domain, the time-frequency unit is composed of 14 multi-carrier symbols, starting with an AGC (which stands for Automatic Gain Control and is used for setting the input level of an amplifier on the receiver side) symbol and ending with a guard symbol. The guard symbol gives each user equipment time to switch between transmission and reception.

[0007] Each time-frequency unit can be used either for transmission or for reception. The waveform used for transmission is DFT-spread OFDM. Transmission and / or reception of the physical sidelink shared channel that mainly stores data occurs only in the multi-carrier symbols labeled PSSCH in the figure. Transmission and / or reception of the physical sidelink control channel that mainly stores control information occurs only in the time-frequency region labeled PSCCH in the figure. DMRS represents the position of the demodulation reference signal or the pilot position and occurs at fixed positions. For the sake of simplicity, hereinafter, the information, control, or pilot signal carried by PSSCH / PSFCH, or the AGC related thereto, is denoted as "data". For data transmission, it is collectively denoted as PSSCH / PSCCH transmission. The time-frequency unit used for data transmission refers to the multi-carrier symbols in the frequency domain (subchannel, subcarrier, resource block, etc.) occupied by PSSCH / PSCCH. The related AGC may be considered to be included or not included in the data transmission.

[0008] On one hand, in the NR system, in frequency range 1 (below 6 GHz), subcarrier spacings of 15 kHz, 30 kHz, and 60 kHz can be used. Other subcarrier spacings (e.g., 120 kHz, 480 kHz, 960 kHz) can be used in higher bands, and other values will be introduced at a later time. The waveform used for transmission is orthogonal frequency division multiplexing (OFDM). The number of pilot symbols DMRS is variable, and the position is also variable. Usually, one resource pool is composed of one subcarrier spacing.

[0009] To illustrate this aspect, FIG. 1 further shows a typical slot structure for NR V2X transmission and / or reception. The resource pool can be considered to be divided by a time interval (e.g., a slot) and a frequency interval (e.g., a subchannel). The duration of the time interval and / or the frequency range of the subchannel depend on the subcarrier spacing. The duration of the time interval may correspond to the duration of a given number (e.g., 14, 13, 7, etc.) of multi-carrier symbols that make up the resource pool, or it may be variable. In FIG. 1, the time interval is considered to correspond to the duration of 14 multi-carrier symbols for a given subcarrier spacing.

[0010] FIG. 1 represents a time-frequency unit 102 for NR V2X transmission / reception that spans one time interval in the time domain and one subchannel in the frequency domain. In the time domain, the time-frequency unit is composed of 14 multi-carrier symbols and starts with an AGC (which stands for Automatic Gain Control and is used for setting the input level of the amplifier on the receiver side) symbol. The first part of the time-frequency unit is used for data transmission / reception and ends with a guard symbol, providing time for each user equipment to switch between transmission and reception. When a feedback opportunity is configured within a resource pool, there is a feedback channel (PSFCH, Physical Sidelink Feedback Channel). The second part of the time-frequency unit is used for feedback transmission / reception. In such a case, the feedback channel carrying HARQ-related information is transmitted as a symbol permitted by the PSFCH. The second part of the time-frequency unit starts with its own AGC symbol and ends with its own guard symbol, and the intermediate symbols are used for feedback transmission / reception. The time resources of the PSFCH are (pre-)configured to occur once every time interval for N = 1, N = 2, or N = 4. It is considered that the time-frequency units are aligned so that the feedback opportunities are aligned (fully occupying the multi-carrier symbols across the entire resource pool). Other patterns, for example, in the time domain, variable multi-carrier symbols, or variable time intervals, or irregular PSFCH occurrences separated by a variable number of time intervals are also possible.

[0011] The structure of FIG. 1 represents the possible transmission / reception of different types of information from the perspective of a communication system. Different user devices can perform the actual transmission / reception of different types of information. For example, the first part of a time-frequency unit is used for data transmission from a first user device to a second user device, and the second part of the time-frequency unit is either unused or used for feedback transmission from a third user device to a fourth user device by the third user device. For example, the first part of a time-frequency unit is used for data transmission from a first user device to a second user device, and the second part of the time-frequency unit is used by the same first user device to transmit feedback to a third user device.

[0012] In the first example, the NR time-frequency unit 102 is represented using a 15 kHz subcarrier spacing, and a feedback opportunity including a time resource for PSFCH occurs at this represented time interval.

[0013] In the second example, two consecutive NR time-frequency units 104 are represented using a 30 kHz subcarrier spacing, and a feedback opportunity including a time resource for PSFCH occurs once per time interval.

[0014] In the third example, two consecutive NR time-frequency units 106 are represented using a 30 kHz subcarrier spacing, and a feedback opportunity including a time resource for PSFCH occurs once every two time intervals.

[0015] In the fourth example, four consecutive NR time-frequency units 108 are represented using a 60 kHz subcarrier spacing, and a feedback opportunity including a time resource for PSFCH occurs once every two time intervals.

[0016] Typically, PSCCH transmission is associated with PSSCH transmission and occurs within one or more physical resource blocks on two or three multi-carrier symbols. Therefore, PSCCH occurs in a specific part of the time-frequency unit. However, usually, for a PSSCH transmission that occupies several sub-channels, there is only one PSCCH. In the following, the existence of PSCCH transmission will be ignored, and data transmission will be described collectively without distinguishing between PSCCH and PSSCH. From this perspective, by further ignoring the position where PSCCH occurs or its occurrence, the configurations 100, 102, 104, 106, 108 depicted in FIG. 1 can be described equivalently as referring to time intervals rather than time-frequency units.

[0017] PSFCH carries HARQ feedback via the sidelink from the UE (User Equipment) (hereinafter, Rx UE), which is the intended recipient of the PSSCH transmission, to the UE that performed the transmission (hereinafter, Tx UE). PSFCH transmits a Zadoff-Chu sequence as one PRB (Physical Resource Block) that is repeated over two OFDM symbols (the first of which can be used for AGC) near the end of the sidelink resources within a time interval. The frequency / code resources are implicitly derived from those used by the associated PSSCH transmission, together with the L1 identification information of the UE transmitting the PSSCH and, if groupcast by ACK / NACK feedback is used, the identification information within the group of the UE transmitting the PSFCH. In a time interval without PSFCH, the time interval can be used either for transmission or reception. In a time interval with PSFCH, the time interval can be used for transmission only, reception only, or both transmission and reception (for example, the UE receives PSSCH / PSCCH in the first part of the time interval and transmits PSFCH (associated with the previous PSSCH / PSCCH reception) in the second part of the time interval, or vice versa). The waveform used for transmission is OFDM. The number and position of DMRS symbols may be different.

[0018] When LTE and NR V2X coexist and the PSFCH is configured, PSFCH transmission may cause degradation in LTE V2X transmission, which is also called the "AGC problem". As shown in FIG. 2, take the coexistence of V2X communication using LTE and NR as an example. LTE2 UE202 receives the LTE frame 100 shown in FIG. 1 from LTE1 UE200. When receiving an AGC symbol in the LTE frame, the LTE2 UE sets the input level of the amplifier to the level corresponding to the power received during AGC training. However, at the end of this time interval, the NR2 UE204 physically close to the LTE2 UE starts transmitting the PSFCH associated with the previous PSSCH reception from UE NR1 206. Assume that NR uses the same subcarrier spacing (SCS) as LTE, that is, 15 kHz. This transmission saturates the amplifier of UE LTE2, and the last two multi-carrier symbols (one DMRS, one data symbol, two control symbols) are lost. As a result, the performance of UE LTE2 deteriorates significantly. Since UE LTE2 cannot detect the coexisting NR1 UE and NR2 UE, this transmission cannot be predicted.

[0019] When the NR transmission is set to a subcarrier spacing (SCS) of 30 kHz, the same situation occurs. Assume that there is a feedback opportunity every N time intervals. When the NR PSFCH opportunity is configured with N = 2 (106), at least one LTE symbol (data and control) is affected by the AGC problem, and when the NR PSFCH opportunity is configured with N = 1 (104), up to three LTE symbols are affected by the AGC problem.

[0020] When the NR transmission is set to 60 kHz SCS, similar problems occur when N = 1 or N = 2.

[0021] In a more general situation, a resource pool is shared among NR users with different SCSs, and the same situation occurs. SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

[0022] The present disclosure improves this situation.

Means for Solving the Problems

[0023] A communication method implemented in a device - to - device communication system for transmitting and / or receiving multi - carrier radio signals. The communication method uses a resource pool for this transmission and / or reception. The resource pool is divided in time intervals in the time domain. Each time interval includes X multi - carrier symbols with respect to a first sub - carrier spacing SCS1. At least a part of the X multi - carrier symbols is available for data transmission in each time interval. The resource pool is divided into L1 sub - channels with respect to a first sub - carrier spacing SCS1 in the frequency domain. The resource pool includes a set of N1×L1 time - frequency units. Each set spans N1 time intervals and L1 sub - channels with respect to a first sub - carrier spacing SCS1. Each set is associated with a feedback opportunity and is included in P multi - carrier symbols with respect to a first sub - carrier spacing SCS1 that are not available for data transmission with respect to a first sub - carrier spacing SCS1 in the time domain. The feedback opportunity is such that SCS2 = k1×SCS1 and k1>1, with respect to a second sub - carrier spacing SCS2 in the time domain and max R = k1×P - 2. It includes at least one, up to a maximum of R max time - frequency resources with respect to a second sub - carrier spacing SCS2, included in a duration corresponding to multi - carrier symbols. The time - frequency resources are available for feedback transmission. A method is proposed in which the feedback opportunity starts at least after the end of a first guard time guard1 after a multi-carrier symbol available for data transmission regarding a first sub-carrier spacing SCS1, and the feedback opportunity ends at least before a second guard time guard2 before the start time of another multi-carrier symbol available for data transmission regarding the first sub-carrier spacing SCS1.

[0024] Considering that the guard interval needs to have the duration of one or more multi-carrier symbols, the value of R max further decreases to k1×P-3.

[0025] A multi-carrier symbol available for data transmission is understood to be a multi-carrier symbol (e.g., an OFDM symbol, a DFT-spread OFDM symbol, etc.) that is used or at least partially used for data transmission (including information, control, or pilot signals) by at least one user equipment in a communication system. A multi-carrier symbol available for data transmission is a multi-carrier symbol in which data transmission occurs on one or several sub-carriers. This does not mean that the symbol is systematically used for transmission, or that it has been detected as not being occupied from a sensing perspective by a user planning data transmission.

[0026] A resource pool is understood to be a pool, or group, or set of time-frequency resources where device-to-device communication occurs. When multiple subcarrier spacings and / or multiple waveforms / RATs coexist in the same resource pool (or equivalently, within different overlapping or duplicated resource pools), it is assumed that there is time alignment and / or frequency alignment between them. Time alignment means that a part of the time intervals (or slots, sub-frames, symbols, or other time units) of different subcarrier spacings and / or different RATs starts at the same time or the start time boundaries coincide. Frequency alignment means that subcarriers from different subcarrier spacings and / or different RATs are aligned on a common raster. For example, the subcarriers with a larger subcarrier spacing may be a subset of the subcarriers with a smaller subcarrier spacing. For example, a part of the resource blocks of different subcarrier spacings and / or different RATs starts at the same frequency or the start frequency boundaries coincide.

[0027] Therefore, different subcarrier spacings can be used between data transmission and feedback transmission, and various advantages can be obtained, such as improving the system throughput or enabling coexistence with other systems.

[0028] SCS1 and SCS2 are values of subcarrier intervals, usually 15 kHz or a multiple of 15 kHz. L1 and N1 are positive integer values. Assume k1 is a positive integer value. P is a positive integer value of 1 or more. A typical value is 1 when there is no feedback opportunity within the time interval, or 4 when there is a feedback opportunity within the time interval (however, the value is not limited to 1 and 4). guard1 and guard2 are positive values greater than 0 representing the duration without transmission / reception in a specific transmission format, or slot format, or subcarrier interval. guard1 and guard2 are the durations during which the user equipment switches between transmission and reception. Such durations correspond to the duration of a multi-carrier symbol or a ratio of the duration of a multi-carrier symbol in the same or different subcarrier intervals, or are fixed to an absolute duration of a magnitude such as microseconds.

[0029] In this description, a resource pool storing multiple subcarrier intervals is mentioned. Similarly, it can be considered that there are multiple overlapping resource pools where each resource pool stores a single subcarrier interval, or there are multiple resource pools multiplexed in the time domain where each resource pool stores a single subcarrier interval. In this regard, "resource pool", "different overlapping resource pools", and "different resource pools multiplexed in the time domain", or "group of resource pools" are considered equivalent in explaining time-frequency division where several subcarrier intervals coexist.

[0030] This description mentions communication in one resource pool, but the communication system may use several different resource pools of the same or different configurations simultaneously.

[0031] This description mainly refers to communications with different carrier intervals. In such cases, the feedback opportunity is at least one, maximum R max stored in multi-carrier symbols available for feedback transmission, including time-frequency resources for a second sub-carrier spacing SCS2, where SCS2 = k1×SCS1 and k1>1, and R maxIt is = k1 × P-2. In this description, although communication with different carrier intervals is mentioned, many different embodiments are envisioned for obtaining multi-carrier symbols of the same content. Taking the multi-carrier symbol of SCS1 as an example, in this case, a given sequence is occupied for each k1-th sub-carrier, and k1 - 1 between the two occupied sub-carriers is set to 0. Before inserting the cyclic prefix, at the output of the OFDM modulator, this symbol with SCS1 is equal to the number of repetitions k1 of the OFDM symbol with sub-carrier interval SCS2 = k1 × SCS1 (same content and same duration), and modulates the same given sequence. For example, when k1 = 2, one PSFCH(SCS1) symbol with SCS1, where only every other sub-carrier is occupied in the sub-carriers assigned / intended for transmission (i.e., in the frequency domain, after one occupied sub-carrier, one null sub-carrier follows), the PSFCH symbol is the same as [PSFCH(SCS2), PSFCH(SCS1)], or equivalent to [AGC(SCS2) PSFCH(SCS2)] with SCS2 = 2 × SCS1. In the following description, the multi-carrier symbol with sub-carrier interval SCS2 = k1 × SCS1 is equivalent to a part of the multi-carrier symbol with sub-carrier interval SCS1 where only every k1-th sub-carrier is occupied. In other words, the multi-carrier symbol with sub-carrier interval SCS2 = k1 × SCS1 is equivalent to an equal part of k1 of the multi-carrier symbol with sub-carrier interval SCS1 where only every k1-th sub-carrier is occupied. The time / frequency resources for the second sub-carrier interval SCS2 = k1 × SCS1 are interpreted as time / frequency resources with the same duration and frequency span as transmission with SCS2, but are occupied by (a part of) the transmission with SCS1. The time / frequency resources for the second sub-carrier interval SCS2 = k1 × SCS1 are k1 times shorter in duration and k1 times larger in frequency span than the time / frequency resources for the first sub-carrier interval SCS1.The PRB for SCS2 (12 consecutive sub - carriers in SCS2) can be described equivalently to 12 consecutive groups k1 of sub - carriers of SCS1.

[0032] From this perspective, this description mentions communication with different carrier intervals, which is equally applicable when the feedback opportunity includes time - frequency resources related to the same sub - carrier interval SCS1. In this case, when there are at least 1 and at most R” max = P - 1 multi - carrier symbols in the feedback opportunity, only the k1 - th sub - carrier is occupied and k1>1. Thus, the advantages of this method can be obtained, and symbols of equivalent content can be generated without significantly changing the hardware compared to the case where only SCS1 is supported. As a supplementary feature, one or several cyclic prefixes of appropriate length can be additionally introduced in the time domain, either at the beginning of c and / or between any of the k1 - equal segments of the above - mentioned symbols. Thus, the total duration of the original symbol (including the cyclic prefix) can be maintained, and time alignment between different users can be guaranteed.

[0033] The proposed method enables co - existence in the same resource pool of several time - interval formats with different sub - carrier intervals for the purpose of avoiding the AGC problem caused by feedback transmission. Furthermore, for the purpose of achieving a convenient trade - off between the performance of the data part and the performance of the feedback part in transmission, symbols with different sub - carrier intervals can co - exist within the same time interval.

[0034] The proposed method associates, on the one hand, the time - frequency unit available for data / control transmission and reception with sub - carrier interval SCS1, and on the other hand, the time - frequency resources available for feedback (e.g., HARQ ACK / NACK) transmission and reception with sub - carrier interval SCS2.

[0035] Optionally, a given set of N1×L1 time-frequency units is divided into a plurality of subsets, and at least a first subset of the plurality of subsets is associated with a set of time-frequency resources of a feedback opportunity associated with the given set, and at least a second subset of the plurality of subsets is not associated with any time-frequency resource of a feedback opportunity associated with the given set with respect to a second subcarrier spacing SCS2.

[0036] Therefore, transmissions with HARQ enabled and transmissions with HARQ disabled can coexist without wasting feedback resources.

[0037] Optionally, a given set of N1×L1 time-frequency units is divided into a plurality of subsets, and at least two of the plurality of subsets are associated with corresponding sets of time-frequency resources for feedback opportunities associated with the given set. Each of the corresponding sets of time-frequency resources is stored in multi-carrier symbols that differ with respect to the sub-carrier spacing SCS2, and / or each of the corresponding sets of time-frequency resources is associated with a different group of orthogonal cyclic shift pairs. Therefore, it is possible to increase the sub-carrier spacing for feedback transmission without reducing the multiplexing capacity of the PSFCH. Optionally, at least one time-frequency unit in a given set of N1×L1 time-frequency units is associated with a time-frequency resource included in a frequency region within different physical resource blocks that is within a maximum of floor(N1×L1 / k1), or within a maximum of ceil(N1×L1 / k1), of the feedback opportunities associated with the given set. The physical resource blocks are formed from 12 consecutive sub-carriers with respect to the second sub-carrier spacing SCS2. As a variant, at least one time-frequency unit in a given set of N1×L1 time-frequency units is associated with a time-frequency resource included in a frequency region within different physical resource blocks that is less than (N1×L1) of the feedback opportunities associated with the given set. The physical resource blocks are formed from 12 consecutive sub-carriers with respect to the second sub-carrier spacing SCS2.

[0038] At least one of the subsets is understood to store at least one time-frequency unit. As a variant, all of the subsets are understood to store at least one time-frequency unit.

[0039] Similarly, at least one time-frequency unit in a given set of N1×L1 time-frequency units is associated with the time-frequency resources of a feedback opportunity associated with the given set. In the frequency domain, in at least one multi-carrier symbol having a first sub-carrier spacing SCS1 at a feedback opportunity, only every k1-th sub-carrier is occupied.

[0040] Therefore, with respect to the case of using the same sub-carrier spacing between data transmission and feedback transmission, feedback at a wider sub-carrier spacing is possible without changing the mapping rule.

[0041] Optionally, each time interval including X multi-carrier symbols regarding the first sub-carrier spacing SCS1 is a first type of time interval. The resource pool is divided in the time domain into time intervals of a second type. Each time interval of the second type includes Y multi-carrier symbols regarding a third sub-carrier spacing SCS0 where SCS1 = k0×SCS0 and k0≥1. In the Y multi-carrier symbols, at least a part is available for data transmission in each time interval of the second type, and P0≥1 multi-carrier symbols are not available for transmission in each time interval of the second type. At least one feedback opportunity is included within P0 multi-carrier symbols in the time domain. It is considered that SCS0 is usually a sub-carrier spacing value of 15 kHz or a multiple of 15 kHz, and Y, k0, and P0 are integer values. X may or may not be equal to Y.

[0042] Therefore, the proposed method further enables the coexistence of such a mixed time interval and a second type of time interval with a narrower sub-carrier spacing SCS0 without causing an AGC problem.

[0043] Optionally, N1 is a multiple of k0, and for any feedback opportunity time-frequency resource, in the time domain, with respect to the second subcarrier spacing SCS2 = k1×SCS1, there is at least one and at most R' max = k1×k0×P0 - 2 multi-carrier symbols within the duration corresponding to them. Further, with respect to the second subcarrier spacing SCS2 = k1×SCS1, there is at least one and at most R' max = k1×k0×P0 - 2 multi-carrier symbols, and equivalently, the duration corresponding to them is expressed as at least 1 / k1 and at most k0×P0 - 1 multi-carrier symbols corresponding to the duration with respect to SCS1.

[0044] Optionally, the value of N1 is different among the sets of N1×L1 time-frequency units. Note that each set of N1×L1 time-frequency units contains N1 time intervals, and each time interval contains X multi-carrier symbols with respect to the first subcarrier spacing SCS1. Usually, the value of X is fixed for a resource pool (e.g., 7, or 13, or 14, etc.), but in this description, the case where the value of X changes from one time interval to another or from one set of time intervals to another set of time intervals is also mentioned.

[0045] Therefore, the proposed method further enables a set of configurations in which such a mixed time interval and a second type of time interval with a narrower subcarrier spacing SCS0 can coexist.

[0046] A device-to-device communication system includes a user equipment configured to transmit and / or receive at least one multi-carrier radio signal using a resource pool, The resource pool is divided in the time domain into time intervals, each time interval contains X multi-carrier symbols with respect to the first subcarrier spacing SCS1, and at least a part of the X multi-carrier symbols is available for data transmission in each time interval, The resource pool is divided into L1 sub-channels with respect to a first sub-carrier spacing SCS1 in the frequency domain, The resource pool includes a set of N1×L1 time-frequency units, each set spanning N1 time intervals and L1 sub-channels with respect to the first sub-carrier spacing SCS1. Each set is associated with a feedback opportunity included within P multi-carrier symbols that are not available for data transmission with respect to the first sub-carrier spacing SCS1 in the time domain with respect to the first sub-carrier spacing SCS1, The feedback opportunity includes time-frequency resources with respect to a second sub-carrier spacing SCS2, where SCS2 = k1×SCS1 and k1>1. In the time domain, with respect to the second sub-carrier spacing SCS2 and R max = k1×P - 2, at least one and at most R max multi-carrier symbols corresponding to the duration are included, and the time-frequency resources are available for feedback transmission, The feedback opportunity starts at least after the end of a first guard time guard1 after a multi-carrier symbol available for data transmission with respect to the first sub-carrier spacing SCS1, and the feedback opportunity ends at least before a second guard time guard2 before the start time of another multi-carrier symbol available for data transmission with respect to the first sub-carrier spacing SCS1. A device-to-device communication system is further proposed.

[0047] A computer program is further proposed, which includes instructions for causing a processor to execute the above method when the program is executed by the processor.

[0048] When at least a part of the exchange is performed according to the above method, the behavior of many user equipments (UEs) for performing resource allocation, transmission, and reception becomes possible. Next, a non-limiting list of such possible UE behaviors is shown in the following paragraphs. If the UE behavior includes selecting a time-frequency unit or resource for transmission, it is suggested that the UE can further perform transmission using the selected time-frequency unit or resource.

[0049] A user equipment of the above device-to-device communication system, wherein the user equipment selects a group of time-frequency units for data transmission from a set of N1×L1 time-frequency units related to a first subcarrier spacing SCS1, and the time-frequency units within the group are within a subchannel with an index of L start ≦L end and within a time interval T start ~L end wherein T start ≦T end and within a time interval T start ~T end and when the user equipment is configured to enable HARQ for data transmission, at least the time-frequency units within subchannel L and time unit T start are associated with a set of time-frequency resources of feedback opportunities associated with the set, start and when the user equipment is configured to disable HARQ for data transmission, at least the time-frequency units within subchannel L and time unit T start are not associated with a set of time-frequency resources of feedback opportunities associated with a given set, and the user equipment is further proposed. start is not associated with a set of time-frequency resources of feedback opportunities associated with a given set, and the user equipment is further proposed.

[0050] A user equipment of the above device-to-device communication system, wherein the user equipment selects a group of time-frequency units for data transmission from a set of N1×L1 time-frequency units related to a first subcarrier spacing SCS1, and the time-frequency units within the group are within a subchannel with an index of L start ≦Lend where the index is L start ~L end within the sub-channel of and T start ≤T end where the time interval T start ~T end is within and when the user equipment is configured with HARQ enabled for data transmission, all time-frequency units within the group are associated with a set of time-frequency resources of feedback opportunities associated with the set, when the user equipment is configured with HARQ disabled for data transmission, the time-frequency units within the group are not associated with a set of time-frequency resources of feedback opportunities associated with the set, and a user equipment is further proposed.

[0051] Therefore, the user equipment can select appropriate resources without wasting data and feedback resources for HARQ-enabled transmissions and / or HARQ-disabled transmissions.

[0052] The user equipment of the above device-to-device communication system, the feedback opportunity is used for the first type of feedback transmission and further includes a first type of time-frequency resource related to a first subcarrier spacing SCS1 stored in a first multi-carrier symbol in the time domain, the time-frequency resource related to a second subcarrier spacing SCS2 is a second type of time-frequency resource used for the second type of feedback transmission and stored in a second multi-carrier symbol in the time domain, the second multi-carrier symbol does not overlap with any of the first multi-carrier symbols in the time domain, the user equipment performs a selection step between the first type of feedback transmission and the second type of feedback transmission, and the selection step is further proposed by the user equipment based on criteria related to the detected transmission or the intended transmission. This criterion is a) Detecting, by a user equipment, the existence of a transmission overlapping with at least one of the time-frequency resources of the first type, and / or b) Regarding that, in at least one of the time-frequency resources of the first type, the user equipment intends to perform data transmission. It may also relate to.

[0053] As already mentioned, in this description, communications with different carrier intervals are referred to. This means that, with respect to the first sub-carrier interval SCS1, the time-frequency resources of the first type are stored in the first multi-carrier symbol in the time domain, while with respect to the same sub-carrier interval SCS1, the time-frequency resources of the second type are, during a feedback opportunity, for at least one and up to R” max = P - 1 multi-carrier symbols, only occupy the sub-carriers every k1-th (k1 > 1) sub-carrier, and is similarly applicable. It is understood that the sub-carriers occupied for a given transmission are stored within the group of sub-carriers of the SCS1 allocated / intended for the given transmission (for example, within the set of time-frequency resources for feedback transmission). It is not suggested that the sub-carrier groups formed by the sub-carriers every k1-th across all sub-channels / multi-carrier symbols are simultaneously occupied by the same transmission (from the perspective of the system, these groups are available for transmission, but from the user's perspective, they are not available).

[0054] Therefore, the conventional slot format (the same sub-carrier interval between data and feedback) and the new slot format (different sub-carrier intervals between data and feedback) can coexist in the same resource pool, enabling coexistence with, for example, legacy users (who may not understand the new format), and enabling, for example, having more feedback resources (enhancing the PSFCH multiplexing performance).

[0055] Regardless of whether the feedback transmission is of the first type or the second type, it is configured to receive the feedback transmission from the user equipment, and optionally, detect an indication from the type of the received feedback transmission, and further configured to select a group of time-frequency units for further data transmission from a set of N1×L1 time-frequency units regarding the first subcarrier spacing SCS1 based on the detected indication. A user equipment is further proposed.

[0056] Other features, details and advantages are shown in the following detailed description and figures.

Brief Description of the Drawings

[0057]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

Figure 6

Figure 7

Figure 8

Figure 7

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Figure 10A

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Figure 10B

Figure 11A

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Figure 11B

Figure 12A

Figure 10A

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DETAILED DESCRIPTION OF THE INVENTION

[0058] <Resource Mapping from PSSCH / PSCCH to PSFCH in the Prior Art> Referring to FIG. 3, this figure schematically shows an NR sidelink resource grid or resource pool known from the prior art. The minimum unit of sidelink (SL) communication is a RE (resource element), which is composed of subcarrier k and OFDM symbol l. N SL RB、SC = 12 subcarriers (SCs) form a PRB (physical resource block) 300, or more simply, an RB. The subcarrier spacing is 15×2 μ kHz. μ ∈ {0, 1, 2, 3, 4} are examples of part of the existing numerology of 5G-NR, and usually 14 OFDM symbols correspond to the time interval. In the time domain, a set of 2 μ time intervals corresponds to 1 millisecond. In the frequency domain, there are L subchannels of each N SL subChsize PRBs, and the total number of PRBs available for sidelink transmission at a given subcarrier spacing is N SL RB、SC = L×N SL subChsize pieces.

[0059] In the current specifications (NR Rel.16, Rel.17), the PSSCH and the related PSFCH exist within the same resource pool and have the same numerology. For a given PSSCH transmission, the PSFCH multi-carrier symbols used in HARQ feedback correspond to the PSFCH symbols of the first time interval with respect to the PSFCH after a (pre)configured number K of time intervals after the PSSCH. PSFCH opportunities occur every N PSSCH time intervals. Suppose the last symbol of the PSSCH transmission is in time interval n. The HARQ feedback for this transmission is expected to be in time interval n+a, where a is the smallest integer greater than or equal to K such that time interval n+a stores the PSFCH. There is only one PSFCH OFDM symbol with index l0 in time interval n+a. In the case of a 14-symbol (l = 0 to 13) time interval as shown in Figure 1, l0 = 12. The AGC symbol at position l = 11 has the same content as the PSFCH of OFDM symbol l0 = 12, but is for the purpose of synchronizing the high-power amplifier in the receiver, and it is not assumed that the receiver can decode it / decodes it.

[0060] Therefore, there is a group of L×N PSSCH time-frequency units associated with a single PSFCH OFDM symbol having index l0 at time interval n+a. n is the last time interval of the group of L×N PSSCH time-frequency units, and a is the smallest integer greater than or equal to K such that time interval n+a stores the PSFCH opportunity. The PSFCH symbol l0 stores M PRBs in the frequency domain available for PSFCH transmission. By (pre)configuration, it is guaranteed that M is a multiple of L×N, that is, each PSFCH symbol l0 stores set = M / (L×N) sets of L×N PRBs. M is at most M max = L×N SL subChsize PRBs.

[0061] Each time-frequency unit within a group is associated with a specific set of PSFCHs in the PRBs within symbol l0. More precisely, symbol l0 stores L×N PSFCH resources indexed from m = 0 to L×N in the frequency domain, and each such resource is composed of M set PRBs. In one PSFCH transmission, one PRB with index m = 0 to M set -1 is occupied. Up to Q PSFCH transmissions are multiplexed (in the code domain) within the same time-frequency resource x of the set (l0, m). Q is one, two, three, or six pairs of cyclic codes (each pair can be used to distinguish ACK and NACK).

[0062] Therefore, there is the following logical association between a PSSCH time-frequency unit (L i , N i ) from a group of L×N PSSCH time-frequency units and a set of M set ×Q time / frequency / code PSFCH resources: - All M set ×Q time / frequency / code PSFCH resources have the same time l0 corresponding to the group of L×N PSSCH time-frequency units. - The M set ×Q PSFCH resources are in the N i th group of M set PRBs of subchannel L i of PSFCH symbol l0.

[0063] Therefore, in the current technology, the above logical association stipulates the following: - PSSCH and PSFCH have the same SCS, and one PRB is occupied in one PSFCH transmission. - A group of L×N PSSCH time-frequency units that occupy the entire L subchannels within the resource pool over N consecutive time interval durations is associated with a single PSFCH OFDM symbol of index l0 and a predetermined set of Q pairs of cyclic shifts. - Each PSSCH time-frequency unit within a group is associated with a set of M set PRBs within symbol l0, but different PSSCH time-frequency units within a given subchannel have different associated sets within the same subchannel (however, if valid transmissions start in different subchannels, they may not be used effectively), - For each PSSCH time-frequency unit, M set × Q PSFCH time / frequency / code resources are associated.

[0064] In summary, a group of L × N PSSCH time-frequency units that occupy the entire L subchannels within the resource pool over N consecutive time interval durations is associated with L × N × M set × Q PSFCH time / frequency / code resources. Each PSSCH time-frequency unit with index m = 1 ~ L × N within the group is associated with M set × Q PSFCH time / frequency / code resources as follows, - All PSSCH time-frequency units are associated with the same time index l0, - Each PSSCH time-frequency unit is associated with a set of M set different PRBs, and different PSSCH time-frequency units are associated with different sets (non-overlapping in the frequency domain), - Each PSSCH time-frequency unit is associated with the same group of Q cyclic shifts.

[0065] Considering the scenario of a valid PSSCH transmission by the TX UE, the transmission starts at a given start subchannel index L start at a given time-frequency unit, spans L' subchannels, and there are F available PSFCHs used by up to F RX UEs. The exact PSFCH resources used for PSFCH transmission are selected by the RX UE (for PSSCH reception and PSFCH transmission) among the following, -F = M associated with the PSSCH time-frequency unit of the transmission start subchannel set Among the × Q PSFCH resources, or -F = L’ × M associated with the PSSCH time-frequency unit of the L’ subchannels occupied by the transmission set Among the × Q PSFCH resources between any of them.

[0066] The exact resource depends on the layer1 ID of the TX UE, the value F of the RX UE, and the transmission type or identifier (the exact formula for selecting the index i of the PSFCH from among the F possible PSFCH resources is i = (TID + RID) mod (F), where TID is the layer1 ID of the TX UE and RID is the identifier associated with the RX UE).

[0067] <Proposed Association from PSSCH / PSCCH to PSFCH> If the PSFCH and the PSSCH use different subcarrier spacings, it is necessary to change the logical association between the PSSCH with subcarrier spacing SCS1 and the PSFCH with subcarrier spacing SCS2 = k1 × SCS1. Currently, the PSFCH opportunities with the same SCS1 as the PSSCH occupy two ODFM symbols to effectively transmit across all subchannels. Two OFDM symbols are used as guards. In the PSSCH time interval (composed of L PSSCH time-frequency units) that stores the PSFCH opportunity, four symbols (guard + AGC + PSFCH + guard) are the last four OFDM symbols of the PSSCH time interval of SCS1.

[0068] For PSFCH opportunities, or feedback opportunities, these are understood to be groups of consecutive OFDM symbols for multiplexing ACK / NACK feedback from different user equipment, i.e., those available for PSFCH transmission. The AGC symbol is understood to be part of the PSFCH opportunity. Guard symbols (possibly multiple) before and / or after the effective transmission of AGC and PSFCH may or may not be understood to be part of the PSFCH opportunity (the guard symbols are empty and not used in transmission by the UE). In the following description, since the guard symbol is not part of the PSFCH opportunity, and the AGC is part of the PSFCH opportunity but not a PSFCH symbol and is not considered to store time-frequency resources for feedback, this specification considers that it is not counted as a multi-carrier symbol for feedback transmission (different symbol indexings by including / excluding guards and / or AGC from the current definition of PSFCH opportunity are considered equivalent and thus not described here). The PSFCH opportunity is associated with all possible PSFCH resources stored in a group of N1×L1 PSSCH time-frequency units spanning L1 consecutive subchannels in the frequency domain and N1 consecutive time interval durations in the time domain.

[0069] When the SCS of PSFCH transmission is changed from SCS1 to SCS2 = k1×SCS1, the duration of the OFDM symbol is divided by k1, and the frequency span of the OFDM symbol is multiplied by k1. Considering the multiplexing capacity F of PSFCH, it is necessary to newly and logically map PSSCH resources to PSFCH resources. PSFCH transmission occupies one PRB at SCS2 (12×SCS2 kHz).

[0070] Therefore, a communication method implemented in a device-to-device communication system for transmitting and / or receiving a multi-carrier radio signal, the communication method using a resource pool for this transmission and / or reception, The resource pool is divided in time domain by time intervals, and each time interval contains X multi-carrier symbols with respect to the first sub-carrier spacing SCS1. At least a part of the X multi-carrier symbols is available for data transmission in each time interval. In the frequency domain, the resource pool is divided into L1 sub-channels with respect to the first sub-carrier spacing SCS1. The resource pool includes a set of N1×L1 time-frequency units, and each set spans N1 time intervals and L1 sub-channels with respect to the first sub-carrier spacing SCS1. Each set is associated with a feedback opportunity and is included within P multi-carrier symbols with respect to the first sub-carrier spacing SCS1 that are not available for data transmission in the time domain with respect to the first sub-carrier spacing SCS1. The feedback opportunity includes at least one and up to R multi-carrier symbols with respect to the second sub-carrier spacing SCS2 that are available for feedback transmission. The second sub-carrier spacing SCS2 satisfies SCS2 = k1×SCS1 and k1>1, and includes time-frequency resources with respect to the second sub-carrier spacing SCS2. max R = k1×P - 2. max The feedback opportunity starts at least after the end of the first guard time guard1 after the multi-carrier symbols available for data transmission with respect to the first sub-carrier spacing SCS1, and ends at least before the second guard time guard2 before the start time of another multi-carrier symbol available for data transmission with respect to the first sub-carrier spacing SCS1. A method is proposed.

[0071] In the above communication method, for the sake of clarity in explanation, the following terms and expressions are further elaborated: - A multi-carrier symbol (or simply "symbol") is, for example, an OFDM symbol as in the current specifications of NR V2X, or a DFT-spread OFDM symbol as in the current specifications of LTE V2X, or other types of multi-carrier symbols. - The value of N1 is the same for all sets of N1×L1 time - frequency units, or the value of N1 is different for each set of N1×L1 time - frequency units. - The value of k1 is related to the value of N1 such that feedback opportunities associated with different sets of N1×L1 time - frequency units can have time - frequency resources that are conveniently aligned. - Data transmission includes, for example, any message carried by the PSSCH channel and the PSCCH channel, including related reference signals and / or related AGC. - The feedback opportunity itself may not be included in the set of time - frequency units to which the feedback opportunity is associated, but is, for example, part of a subsequent set of time - frequency units. - The feedback transmission indicates feedback for a previous data transmission. The feedback transmission includes, for example, HARQ feedback using the PSFCH, and also further includes the AGC required to send the feedback.

[0072] The above - mentioned communication method is equally applicable when the feedback opportunity includes time - frequency resources related to the same sub - carrier spacing SCS1. When there are at least 1 and at most R” max =P - 1 multi - carrier symbols present in the feedback opportunity, only the k1 - th sub - carrier is occupied (k1>1). Specifically, k1 is 2, 4, or more.

[0073] In this description, an example of a resource pool that stores different subcarrier intervals simultaneously is introduced. Next, various possible time domain configurations related to the above example of the communication method are presented. The following comprehensively covers possible embodiments of the proposed communication method in an NR V2X communication network according to the current specification. For such reasons, hereinafter, it may be referred to as a "multi-carrier symbol", "OFDM symbol", or simply "symbol". These terms are interpreted to have the same meaning in the context of the proposed communication method and are alternatively applicable to other communication networks. In the following, when referring to a "symbol" or "OFDM symbol", it is interpreted to refer to any type of "multi-carrier symbol" suitable for a given communication network.

[0074] <Time interval format where the SCS ratio is k1 = 2 or k1 = 4> As a first example, consider the case where the SCS2 of the PSFCH transmission is twice the SCS1 of the associated PSSCH transmission (k1 = 2). Hereinafter, the expression "PSSCH transmission" is generalized to refer to one or more time-frequency units related to the first subcarrier interval SCS1 occupied by data transmission according to the proposed communication method. Further, the expression "PSFCH transmission" is generalized to refer to one or more time-frequency resources or time-frequency-code resources related to the second subcarrier interval SCS2 occupied by feedback transmission according to the proposed communication method. Expressions such as "PSSCH symbol" or "PSSCH time interval" are related to PSSCH transmission, and expressions such as "PSFCH symbol", "PSFCH time interval", or "PSFCH opportunity" are related to PSFCH transmission.

[0075] Figures 4A and 4B show possible time domain configurations 400 to 414 (ignoring the frequency domain), where the time interval is divided into a first part where PSSCH transmission occurs at SCS1 and a second part where PSFCH transmission occurs at SCS2. The first time domain configuration 400 refers to a time domain configuration known from the prior art (same SCS), and the other time domain configurations 402 to 414 show examples of the present invention where SCS2 = k1 × SCS1. P is selected to be 4, which has the advantage of having the same PSSCH time interval format as the current specification. Although the guard symbol is not associated with a specific subcarrier spacing, it is necessary to maintain a minimum duration to enable switching between transmission and reception, that is, the feedback opportunity can start at least after the first guard time guard1 after the end of the last PSSCH symbol used for PSSCH transmission in the PSSCH time interval, and each feedback opportunity ends at least before the second guard time guard2 before the end of the PSSCH time interval. For example, in one of the proposed illustrated time domain configurations 402, guard1 corresponds to the total duration of three consecutive guard symbols (two for SCS1 and one for SCS2), and guard2 corresponds to the duration of a single guard symbol of SCS2. In the PSFCH opportunity, the PSFCH OFDM symbol can exist up to a maximum of R max = P × k1 - 2 = 6.

[0076] Figures 5A and 5B show possible time domain configurations 500 - 510 (ignoring the frequency domain), where the time interval is divided into a first part where PSSCH transmission occurs at SCS1 and a second part where PSFCH transmission occurs at SCS2 = k1×SCS1. P = 3 (500, 502, 504, 506) and P = 2 (508, 510) have the advantage of increasing the throughput of PSSCH by increasing the number of multi - carrier symbols available for PSSCH in the time interval. The guard symbol is not associated with a specific sub - carrier spacing, but it is necessary to maintain a minimum (non - zero) duration to enable switching between transmission and reception, i.e., the feedback opportunity can start at least after the first guard time guard1 after the end of the last PSSCH multi - carrier symbol used for PSSCH in the time interval, and each feedback opportunity should end before the second guard time guard2 before the end of the time interval. The minimum guard can be made shorter than, for example, the duration of an OFDM symbol at a given SCS. For P = 3, in the PSFCH opportunity, there can be up to P×k1 - 2 = 4 PSFCH OFDM symbols. For P = 4, only up to 2 PSFCH OFDM symbols can be used, but the number of symbols available for PSSCH in the time interval further increases.

[0077] If a larger number of PSFCH multi - carrier symbols than k1 are available, the surplus symbols can be used to increase the reliability of PSFCH transmission (e.g., by repetition, reducing the number of cyclic shift pairs used simultaneously by M set ), or to increase the multiplexing capacity of PSFCH (increase the available PSFCH resources).

[0078] FIG. 6 shows a subset of possible time domain configurations 400, 600 - 606 for k1 = 4. The reference time domain configuration 400 is depicted, which refers to the current "state of the art" configuration (same SCS), while all other depicted time domain configurations 600 - 606 depict examples suitable for the proposed cases when SCS2 = 4×SCS1, and in such examples, respectively, up to R max = 14 different PSFCH OFDM multi - carrier symbols may exist.

[0079] All of the above embodiments correspond to a D2D multi - carrier system with a resource pool having a time interval for PSSCH transmission with a sub - carrier spacing SCS1 spanning L1 sub - channels and having a feedback opportunity occurring every N1 PSSCH time intervals. The P ≤ 4 OFDM symbols at SCS1 with a feedback opportunity at the end of the PSSCH time interval cannot be used for PSSCH transmission at SCS1, so the feedback opportunity stores PSFCH time - frequency resources at SCS2 = k1×SCS1, k1 > 1. Each feedback opportunity stores at least one and up to R max = P×k1 - 2 PSFCH OFDM symbols at SCS2. Each feedback opportunity starts at least after the first guard time guard1 after the end of the last PSSCH symbol used for PSSCH transmission in the time interval, and each feedback opportunity ends before the second guard time guard2 before the end of the time interval.

[0080] Therefore, the time interval formats 402, 404, 406, 408, 410, 412, 414, 500, 502, 504, 506, 508, 510 proposed in FIGS. 4A, 4B, 5A, and 5B enable flexible combination of PSSCH transmission with subcarrier spacing SCS1 and feedback transmission with increased subcarrier spacing SCS2 in the same resource pool. Advantageously, there is a trade-off between the number of PSSCH symbols available for use in the time interval storing the feedback opportunity and the number of PSFCH symbols available for feedback transmission.

[0081] Therefore, the time interval formats 402, 404, 406, 408, 410, 412, 414 proposed in FIGS. 4A and 4B in the case of P = 4 have the advantage of enabling more flexible feedback transmission with increased subcarrier spacing SCS2 without changing the time interval format for PSSCH transmission by subcarrier spacing SCS1 (without specification change).

[0082] Furthermore, the time interval formats 500, 502, 504, 506, 508, 510 proposed in FIGS. 5A and 5B in the case of P = 3 or P = 2 have the advantage of increasing the number of PSSCH symbols available for PSSCH transmission.

[0083] The different time interval formats proposed in FIGS. 4A, 4B, 5A, and 5B achieve different trade-offs between the performance of PSSCH (e.g., throughput) and the performance of PSFCH (e.g., reliability, multiplexing capacity).

[0084] The advantages in the case of k1 = 4 are the same as those in the case of k1 = 2. However, the time interval formats 600, 602, 604, 606 proposed in FIG. 6 have the particularly advantageous characteristic that they have a maximum of two PSFCH symbols (regardless of the P value) and the PSFCH opportunity is included in the last OFDM symbol of SCS1 within the time interval.

[0085] <Association between PSSCH and PSFCH> Assume a resource pool having L sub-channels for PSSCH of SCS1 and a PSFCH period N (i.e., a feedback opportunity occurs every N time intervals of the duration corresponding to SCS1). Optionally, the occurrence of PSFCH is not periodic (i.e., the value of N varies). Optionally, the resource pool includes sub-channels with different sub-carrier intervals such as SCS1, SCS2, SCS0, etc. With this assumption, the resource pool includes the PSSCH of SCS1 and L = L1 sub-channels for PSFCH period N = N1, and the resource pool further includes sub-channels of SCS2, sub-channels of SCS0, etc. For a resource pool with N = 2 and K = 1, respectively, N SL subChsize Take the case where there are L = 4 sub-channels of 12 PRBs (SCS1). Let M’ be the number of PRBs occupied by the PSFCH represented by SCS1. In the example of FIG. 7, M’ takes the maximum value that can be configured, M’ = L × N SL subChsize = 48. The number of PRBs represented as SCS2 and occupied by the PSFCH is at most M = floor(M’ / k1).

[0086] FIG. 7 is a diagram for explaining configuration 700 in the prior art (NR specification). In FIG. 7, the AGC symbol and the guard symbol are omitted. In the figures after this figure, only the OFDM symbols storing PSSCH or PSFCH are shown in a simplified form. Also, the position of PSCCH is omitted. The index numbers are just examples, and even if the indexing of PSSCH and / or PSFCH resources is different after FIG. 7, it doesn't matter.

[0087] The first group of L×N = 8 PSSCH time-frequency units indexed by m = 1 to L×N is shown after FIG. 7. The blank at the end of each of the PSSCH time-frequency units indexed by m = {1, 3, 5, 7} corresponds to a multi-carrier symbol that cannot be used for data transmission by the sub-channel spacing SCS1. The blank is considered to be included in each of the PSSCH time-frequency units indexed by m = {1, 3, 5, 7}. To the right of the first group of 8 PSSCH time-frequency units, a separate second group of time-frequency units with sub-channel spacing SCS1 is further depicted. The PSFCH opportunities associated with the first group of 8 PSSCH time-frequency units are included in the multi-carrier symbols of the second group of time-frequency units that cannot be used for data transmission with sub-channel spacing SCS1. Sufficient time is required for the UE to receive and process the PSSCH communication and then generate the PSFCH transmission. Therefore, there is an intermediate group of one or more time-frequency units between the first group of PSSCH time-frequency units and the second group of time-frequency units that store the associated PSFCH opportunities. Therefore, K is 1 or more, preferably 2, 3, or more. After FIG. 7, different groups of PSSCH time-frequency units may or may not have the same duration / may store the same number of multi-carrier symbols in the same or some different sub-carrier symbols. The durations of different groups of PSSCH time-frequency units are not considered to be represented to scale in the figure.

[0088] In FIG. 7, the depicted PSFCH opportunities include M set = 6 PSFCH time-frequency resources are divided into L×N = 8 sets, and M' = 48 PRBs are stored. In the code area, for a PSFCH spanning one PRB (12 sub-carriers), 12 cyclic shifts CS for generating orthogonal codes (CS = 0 to 11) are considered and composed of 6 pairs. For each i-th pair q iAssume that (i = 0~5) stores the CS pair (i, i + 6). In FIG. 7, for example, assume that Q’ = 3 CS pairs are used, such as q = {0, 2, 4} (any other combination is also possible). Therefore, for the total of F’tot = 144 PSFCH time / frequency / code resources in the group, there are F’ = 18 PSFCH resources associated with each PSSCH time interval.

[0089] That is, a group of L×N = 8 PSSCH logical time-frequency units is associated with a PSFCH opportunity that stores a single OFDM PSFCH symbol (R’ = 1) of the same SCS (k1 = 1) as follows: - All PSSCH time-frequency units are associated with the same time index l0 (they all exist within the same OFDM symbol), - Each PSSCH time-frequency unit is associated with a set of M set = M’ / (L×N)=6 different PRBs, and different PSSCH time-frequency units are associated with different sets (non-overlapping, i.e., discontinuous in the frequency domain). - Each PSSCH time-frequency unit is associated with the same group of Q’ = 3 cyclic shifts.

[0090] In the following figures, different options are shown for associating each PSSCH logical time-frequency unit of SCS1 (from the group of L×N logical time-frequency units within N time intervals associated with a feedback opportunity (see FIGS. 4A, 4B, 5A, 5B, and 6)) with a group of PSFCH time / frequency / code resources where SCS2 = k1×SCS1 (k1>1). Each feedback opportunity stores R PSFCH OFDM symbols of SCS2, where 1≦R≦R max = P×k1 - 2. These associations can be applied to any of the conforming time-domain time interval structures already described in relation to the examples depicted in FIGS. 4A, 4B, 5A, 5B, and 6.

[0091] In FIG. 8, a configuration 800 is shown in which a group of L×N PSSCH time-frequency units is divided into two subgroups SG1={PSSCH1, PSSCH3, PSSCH5, PSSCH7}, and SG2={PSSCH2, PSSCH4, PSSCH6, PSSCH8}. The PSFCH resources associated with SG1 are in different PSFCH OFDM symbols from the PSFCH resources associated with SG2. Thus, the subcarrier spacing is widened and the equivalent number of PRBs in an OFDM symbol is divided by k1, but the multiplexing capacity of the PSFCH is the same as the reference case from the prior art without changing the assigned cyclic shift for both the PSSCH time-frequency unit (F) and the total of the L×N groups of PSSCH time-frequency units.

[0092] In Fig. 9, configuration 900 is shown in which a group of L×N PSSCH time-frequency units is divided into two subgroups SG1 = {PSSCH1, PSSCH3, PSSCH5, PSSCH7}, and SG2 = {PSSCH2, PSSCH4, PSSCH6, PSSCH8}. The PSFCH resources associated with SG1 have an associated group of orthogonal cyclic shift pairs that is different from the PSFCH resources associated with SCS2. All time-frequency units of SG1 are associated with q = {0, 2, 4}. All time-frequency units of SG2 are associated with q = {1, 3, 5}. PSSCH1 of SG1 and PSSCH2 of SG2 use the same time-frequency resources, but are associated with different groups of CS codes, so the associated PSFCH resources are different. Thus, the subcarrier spacing is widened and the equivalent number of PRBs in an OFDM symbol is divided by k1, but the multiplexing capacity of the PSFCH is the same as in the reference case for both the PSSCH time interval (F) and the total of the group of L×N PSSCH time intervals. In Fig. 9, the time / frequency feedback resources labeled 1 to 8 are the only time / frequency feedback resources in the feedback opportunity. In a variant form, the feedback opportunity can further include time / frequency feedback resources not shown in the figure, for example, another type of time / frequency feedback resource (e.g., having an SCS1 subcarrier spacing or a subcarrier spacing other than SCS2).

[0093] In FIGS. 10A and 10B, configurations 1000 and 1002 are shown in which a group of L×N PSSCH time-frequency units is divided into two subgroups SG1 = {PSSCH1, PSSCH3, PSSCH5, PSSCH7}, and SG2 = {PSSCH2, PSSCH4, PSSCH6, PSSCH8}. There is no PSFCH resource associated with subcarrier spacing SCS2 in SG1. As a variant, SG1 has a PSFCH resource associated with SCS1 (e.g., PSFCH at time interval type 400 in FIG. 4). As a variant, SG1 may not have an associated PSFCH resource (regardless of SCS). For example, a transmission with HARQ enabled stores only PSSCH time-frequency units from SG2, and a transmission with HARQ disabled stores only PSSCH time-frequency units from SG1. Therefore, in order to promote an increase in the number of PSSCH symbols within a time interval, the number of PSFCH symbols may be reduced.

[0094] As can be seen in FIG. 10A, in this solution, the multiplexing capacity of PSFCH(F) for each of the PSSCH time-frequency units in SG2 is maintained, but the overall multiplexing capacity Ftot of PSFCH decreases. As depicted in FIG. 10B, this can be compensated for by increasing the number of CS codes as much as possible and necessary.

[0095] In FIGS. 11A and 11B, configurations 1100 and 1102 are shown where a group of L×N PSSCH time-frequency units is divided into two subgroups SG1 = {PSSCH1, PSSCH2, PSSCH5, PSSCH6}, and SG2 = {PSSCH3, PSSCH4, PSSCH7, PSSCH8}. There is no PSFCH resource associated with subcarrier spacing SCS2 in SG2. As a variant, SG1 may not have an associated PSFCH resource (regardless of the SCS). For example, a valid HARQ transmission starts only with PSSCH time-frequency units from SG1, and an invalid HARQ transmission starts only with PSSCH time-frequency units from SG2. In this example, SG1 and SG2 store time-frequency units from different subchannels. Therefore, to promote improving the throughput of PSSCH transmission, the number of PSFCH symbols may be reduced.

[0096] In this solution, the multiplexing capacity of PSFCH(F) for each of the PSSCH time-frequency units in SG2 is maintained, but the overall multiplexing capacity Ftot of PSFCH decreases. This can be compensated by increasing the number of CS codes as much as possible and necessary (as depicted in FIG. 11B).

[0097] In FIGS. 12A and 12B, with respect to the M' set value of reference FIG. 7, configurations 1200 and 1202 are shown where the value of M set decreases by a factor k. k is an integer greater than 1. In this specific example, k = k1. Therefore, except for the M set value, there may be no specification change regarding the currently adopted configuration in the NR specification, so the specification is simplified and convenient. In this solution, the multiplexing capacity (F) of each PSFCH of the PSSCH time-frequency unit is divided by the factor k, and this can be compensated by increasing the number of CS codes as much as possible and necessary (as depicted in FIG. 12B).

[0098] Combinations of different features are also envisioned. An example of configuration 1300 with multiple combinations of the above features is shown in FIG. 13, although other combinations are also envisioned. In FIG. 13, k1 = 4. The group of L×N PSSCH time-frequency units is divided into three subgroups SG1 = {PSSCH1, PSSCH2}, SG2 = {PSSCH5, PSSCH6}, and SG3 = {PSSCH3, PSSCH4, PSSCH7, PSSCH8}. There is no PSFCH resource associated with subcarrier spacing SCS2 in SG3, and the PSFCH resource associated with SG1 is in a different PSFCH OFDM symbol from the PSFCH resource associated with SG2. For example, a HARQ-enabled transmission starts only with PSSCH time-frequency units from SG1 or SG2, and a HARQ-disabled transmission starts only with PSSCH time-frequency units from SG3. Thus, k1 = 4 is supported in advantageous time interval formats like all formats 600, 602, 604, 606 except the first row of FIG. 6.

[0099] The different embodiments of FIGS. 8, 9, 10A, 10B, 11A, 11B, 12A, 12B, and 13 provide different trade-offs that can compensate for a decrease (by factor k1) in the number of subcarriers available in an OFDM symbol of fixed bandwidth when increasing the subcarrier spacing by factor k1.

[0100] In the reference case of FIG. 7, the L×N PSSCH time-frequency units are associated with a global number L×N×M set ×Q different PSFCH time / frequency / code resources, where M set = M / (L×N), and M is configured for convenience (usually M = L×N×N SL RB、SC sub-channels).

[0101] In the described case, for the proposed mapping, the L×N PSSCH time-frequency units are associated with a global number L×N×M setAre associated with different PSFCH time / frequency / code resources of <Q×R / k1> different (higher) SCSs. Solutions that can maintain at least the same PSFCH multiplexing capacity are as follows: · Increase any one of R, or Q, or R×Q, such as Q×R / k1≥1 · The number of PSSCH time-frequency units associated with the PSFCH resource (by selecting a subset of subchannels and / or time positions), or M set Or the size of L×N×M set Decrease any one of them (e.g., by at least a factor of k1), or · The above combinations.

[0102] Other solutions are possible, but there may be problems in terms of the multiplexing capacity of the PSFCH.

[0103] <Proposed configuration> In a pool such as SCS1 = k0×SCS0 (and k0≥1), assume that another time interval format based on the subcarrier spacing SCS0 is allowed. The time interval of SCS0 may not store PSFCH opportunities and is composed of an AGC symbol, followed by data / control and / or pilot transmissions, and a guard of symbols of P0 (P0≥1).

[0104] This is the case, for example, in a scenario where LTE transmissions and NR transmissions of time interval format 100 as depicted in FIG. 1 coexist.

[0105] In this scenario, the resource pool has a first type of time interval with subcarrier spacing SCS1 and a second type of time interval with subcarrier spacing SCS0. The first type of time interval and the second type of time interval overlap in the time domain, and a certain (e.g., periodic) alignment of the starts of the first type of time interval and the second type of time interval occurs. For example, each start of the second type of time interval coincides with every k0-th start of the first type of time interval. The second type of time interval includes multi-carrier symbols available for PSSCH transmission. Further, in PSSCH transmission at SCS0, at the end of each time interval of the second type, P0 ≥ 1 OFDM symbols at SCS0 cannot be used, and the time domain of the final P0 OFDM symbols at SCS0 includes one or more feedback opportunities. In this configuration, N is a multiple of k0, and the time-frequency resources of the feedback opportunities are, in the time domain, at least one and at most R’ max =k1×k0×P0 - 2 is included within the duration corresponding to multi-carrier symbols at SCS2.

[0106] In FIG. 14, one (second type) time interval 100 at SCS0 is shown at the top of the figure, two consecutive time intervals 1400 at SCS1 = 2×SCS0 are shown, and the PSFCH opportunities at SCS2 = 2×SCS1 occur every N = 2 time intervals. Different time intervals / parts of time intervals are used by different UEs for transmission and / or reception. In this figure, the frequency domain is ignored.

[0107] In the time interval configuration 1400 shown at the bottom of FIG. 14, with the restrictions N = k1 = 2 and the number of PSFCH symbols R max = 2, it is advantageously avoided that PSFCH transmission collides with the symbols of SCS0 in the time domain. At the logical association level, a frequency domain overlap occurs between (a part of) the guard symbols at SCS0 and (a part of) the PSFCH transmission (although this is not necessarily assumed during valid transmission). The time interval 1400 storing the PSFCH opportunities follows one of the formats 600, 602, 604, 606.

[0108] In FIG. 15, one (second type) of time interval configurations 100 in SCS0 is shown at the top of the figure, and one of the continuous time interval configurations 400 in SCS1 = SCS0 is shown. The PSFCH opportunity at SCS2 = 4×SCS1 is once every N = 1 time interval. Transmission in the conventional NR time interval format in SCS0 is also possible in the same resource pool. Different time intervals / parts of time intervals are used by different UEs for transmission and / or reception. In this figure, the frequency domain is ignored.

[0109] In the time interval configuration 1500 shown at the bottom of FIG. 15, due to the restrictions N = k1 = 1 and R max = 2 for the number of PSFCH symbols, it is advantageously avoided that the PSFCH transmission collides with the symbols of SCS0 in the time domain. At the logical association level, frequency domain overlap occurs between (a part of) the guard symbols of SCS0 and (a part of) the PSFCH transmission (although it is not necessarily assumed during valid transmission). The time intervals storing the PSFCH opportunities follow any of the formats 402, 404, 500, 502, 508, 510.

[0110] <Proposed UE Behavior> Furthermore, a UE is proposed that uses the sidelink resource grid defined in relation to any of the described examples and features, either alone or in combination, to perform resource selection, and / or transmission, and / or reception.

[0111] Examples of such behavior include, for example, PSSCH and specific resource selection for related transmission.

[0112] For example, the UE is configured to perform resource selection for PSSCH transmission at SCS1. For example, if the UE is configured with HARQ enabled, the lowest (in the variant, the highest) subchannel index in the allocation selects the resources corresponding to the PSSCH time-frequency units within any subgroup of time-frequency units having the corresponding PSFCH resources.

[0113] For example, the UE is configured to perform resource selection for PSSCH transmission at SCS1. For example, if the UE is configured with HARQ enabled, the lowest (in the variant, the highest) subchannel index in the allocation selects the resources corresponding to the PSSCH time-frequency units within at least one subgroup of time-frequency units not having the corresponding PSFCH resources.

[0114] For example, the UE is configured to perform PSFCH transmission by deriving the parameters for PSFCH transmission at SCS2 based on the parameters configured for PSSCH transmission at SCS1 and the knowledge of the k1 value.

[0115] In the case of actual transmission, as already explained, the UE may implement the PSFCH symbols natively generated at the subcarrier spacing SCS2, or generate equivalently the PSFCH symbols generated at the subcarrier spacing SCS1 using only the k1-th subcarrier among the subcarriers (allocated for / corresponding to the PSFCH transmission). In this case, the UE transmits the entire PSFCH symbol generated at SCS1 (for example, when k1 = 2, this symbol represents the AGC + PSFCH at SCS2), or only a part of this symbol (for example, when k1 = 4, this symbol is composed of four identical segments in the time domain, for example, the UE discards the first and the last segments and transmits only the second and the third segments (representing the AGC + PSFCH at SCS2)).

[0116] For example, for PSFCH transmission, the UE is configured to select one of two different time interval formats (e.g., either the central time interval format 400 in FIG. 15 or the lower time interval format 1500 in FIG. 15) according to criteria related to the detected or intended transmission by at least one of the time-frequency resources related to the first subcarrier spacing SCS1. One of such time interval formats is defined such that the time-frequency resources available for PSFCH transmission are included within a duration corresponding to at least one and up to R' max =k1×k0×P0 - 2 multi-carrier symbols. This criterion is related to, for example, the following. - Detection of the presence of a transmission by a second type of time interval (e.g., the topmost in FIG. 15) that overlaps with the PSFCH transmission (e.g., if the presence of LTE is detected, use the PSFCH with the higher SCS), and / or, - The intention to transmit PSSCH data in the same time interval as the PSFCH transmission (e.g., when the data to be transmitted is not only the PSFCH but also uses the same PSFCH as the PSSCH with the same SCS as the "normal" time interval format).

[0117] For example, the UE is configured to blindly search for multiple types of PSFCH transmissions (e.g., both SCS1 and SCS2).

[0118] For example, UE-A is configured to receive the PSFCH by using the type (SCS1, SCS2) of the received PSFCH as an input (indirect information regarding the presence of LTE detected by the intended receiver UE-B) to the resource selection process for transmitting to UE-B according to the method from UE-B.

Claims

1. A communication method implemented in a device - to - device communication system for transmitting and / or receiving multi - carrier wireless signals, the communication method using a resource pool for the transmitting and / or receiving, The resource pool is divided at time intervals in the time domain, and each time interval includes X multi-carrier symbols with respect to a first sub-carrier spacing SCS １ and at least a part of the X multi-carrier symbols is available for data transmission in each time interval The resource pool is divided into L sub-channels with respect to the first sub-carrier spacing SCS in the frequency domain １ and １ is divided into L sub-channels The resource pool is N １ × L １ sets of time - frequency units, each set including N １ time intervals and L １ sub - channels related to the first sub - carrier spacing SCS 1 spanning, and each set is associated with a feedback opportunity and is included in P multi - carrier symbols related to the first sub - carrier spacing SCS １ not available for data transmission in the time domain related to the first sub - carrier spacing SCS １ in the first sub - carrier spacing SCS The feedback opportunity is SCS ２ = k １ ×SCS １ and k １ > 1, and in the time domain, the second subcarrier spacing SCS ２ with respect to, and R ｍａｘ = k １ ×P - 2, at least one, up to R ｍａｘ corresponding to the duration of the multi - carrier symbols, including the time - frequency resource for the second subcarrier spacing SCS ２ which is available for feedback transmission The feedback opportunity starts at least after the end of a first guard time guard of a multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS １ and ends before the start time of a second guard time guard before the start of another multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS １ The feedback opportunity starts at least after the end of a first guard time guard of a multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS 1 and ends before the start time of a second guard time guard before the start of another multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS ２ beforehand, method.

2. N １ × L １ A given set of time - frequency units is divided into a plurality of subsets, and at least a first subset of the plurality of subsets is associated with a set of time - frequency resources of the feedback opportunity associated with the given set, and at least a second subset of the plurality of subsets is not associated with the time - frequency resources of the feedback opportunity associated with the given set with respect to the second sub - carrier spacing SCS ２ The method according to claim 1, wherein the second sub - carrier spacing SCS is not associated with the time - frequency resources of the feedback opportunity associated with the given set.

3. N １ × L １ A given set of N time - frequency units is divided into a plurality of subsets, At least two of the plurality of subsets are associated with a corresponding set of time - frequency resources of the feedback opportunities associated with the given set, Each of the corresponding sets of the time-frequency resources is for the second subcarrier spacing SCS ２ stored in different multi-carrier symbols and / or each of the corresponding sets of the time-frequency resources is associated with different groups of orthogonal cyclic shift pairs, the method according to claim 1 or 2.

4. N １ × L １ In at least one time - frequency unit in a given set of N １ × L １ / k １ ), different physical resource blocks, where the physical resource blocks are formed from 12 consecutive sub - carriers with respect to the second sub - carrier spacing SCS, and are associated with the time - frequency resource and are included in the frequency domain within the given set of time - frequency units, the method according to claim 1 or 2. ２ ​

5. The first subcarrier spacing SCS １ Each time interval including X multi-carrier symbols related to the first subcarrier spacing SCS is a time interval of the first type, The resource pool is divided in the time domain by a second type of time interval, and the second type of time interval is SCS １ = k ０ × SCS ０ and k ０ ≥ 1, and includes Y multi-carrier symbols related to a third sub-carrier spacing SCS ０ In the Y multi-carrier symbols, at least a part is available for data transmission in the second type of time interval, and P ０ ≥ 1 multi-carrier symbol is not available for transmission in the second type of time interval At least one of the feedback opportunities is, in the time domain, within the P ０ multi-carrier symbols according to claim 1 or 2, the method according to claim 1 or 2.

6. N １ is a multiple of k ０ and the time-frequency resource for any feedback opportunity is, in the time domain, at least one and up to R ２ = k ’ｍａｘ × k １ × P ０ − 2 multi-carrier symbols, the method according to claim 5, included within the duration corresponding to the multi-carrier symbols ０ ​

7. N １ is different in value among the sets of the １ N × L １ sets of the time-frequency units according to claim 1 or 2.

8. A device - to - device communication system including a user equipment configured to transmit and / or receive at least one multi - carrier wireless signal using a resource pool, The resource pool is divided at time intervals in the time domain, and each time interval includes X multi-carrier symbols with respect to a first sub-carrier spacing SCS １ and at least a part of the X multi-carrier symbols can be used for data transmission in each time interval. The resource pool is divided into L sub-channels with respect to the first sub-carrier spacing SCS in the frequency domain １ and １ is divided into L sub-channels The resource pool is N １ × L １ sets of time-frequency units, each set including N １ time intervals and the first subcarrier spacing SCS １ spanning L １ sub-channels, and each set is, in the time domain, associated with a feedback opportunity included in P multi-carrier symbols that cannot be used for data transmission related to the first subcarrier spacing SCS １ related to the first subcarrier spacing SCS １ as follows The feedback opportunity is SCS ２ = k １ × SCS １ and k １ > 1, and for the second sub - carrier spacing SCS ２ in the time domain, and R ｍａｘ = k １ × P - 2, at least one, up to R ｍａｘ including the time - frequency resource for the second sub - carrier spacing SCS ２ corresponding to the multi - carrier symbols in the duration, and the time - frequency resource is available for feedback transmission The feedback opportunity starts at least after the end of a first guard time guard for a multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS １ and ends at least before the start time of a second guard time guard before another multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS １ A device-to-device communication system. １ and ends at least before the start time of a second guard time guard before another multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS ２ before the start of another multi-carrier symbol available for data transmission related to the first sub-carrier spacing SCS.

9. A computer program including instructions that, when the computer program is executed by a processor, cause the processor to execute the method according to Claim 1 or 2.

10. A user equipment of the device - to - device communication system according to claim 8, wherein the user equipment selects a group of time - frequency units for data transmission from a set of N １ ×L １ time - frequency units related to the first sub - carrier spacing SCS. The time - frequency units within the group are within a sub - channel with an index from L １ to L ｓｔａｒｔ where L ｅｎｄ ≤ L ｓｔａｒｔ and are within a time interval T ｅｎｄ to T ｓｔａｒｔ where T ｅｎｄ ≤ T ｓｔａｒｔ to T ｅｎｄ ​ When the user equipment is configured to enable HARQ for data transmission, subchannel L ｓｔａｒｔ , and at least the time-frequency unit within time unit T ｓｔａｒｔ is associated with a set of time-frequency resources of the feedback opportunity associated with the set, When the user equipment is configured to disable HARQ for data transmission, subchannel L ｓｔａｒｔ , and at least the time-frequency unit within time unit T ｓｔａｒｔ is not associated with the set of time-frequency resources of the feedback opportunity associated with the set, user equipment.

11. A user equipment of the device - to - device communication system according to claim 8, wherein the user equipment selects a group of time - frequency units for data transmission from a set of N １ × L １ time - frequency units, and the time - frequency units within the group are within a sub - channel with an index from L １ to L ｓｔａｒｔ where L ｅｎｄ ≤ L ｓｔａｒｔ and within a time interval T ｅｎｄ where T ｓｔａｒｔ ≤ T ｅｎｄ ≤ T ｓｔａｒｔ to T ｅｎｄ ; When the user equipment is configured to enable HARQ for data transmission, all the time - frequency units in the group are associated with a set of time - frequency resources of the feedback opportunities associated with the set, When the user equipment is configured to disable HARQ for data transmission, the time - frequency units in the group are not associated with a set of time - frequency resources of the feedback opportunities associated with the set. A user equipment.

12. A user equipment of the device - to - device communication system according to Claim 8, The feedback opportunity is used for first-type feedback transmission and is stored in a first multi-carrier symbol in the time domain, the first sub-carrier spacing SCS １ and further includes a first type of time-frequency resource related to the second sub-carrier spacing SCS ２ The time-frequency resource related to the second sub-carrier spacing SCS is a second type of time-frequency resource that is used for the second type of feedback transmission and is stored in the second multi-carrier symbol in the time domain. The second multi - carrier symbol does not overlap with any of the first multi - carrier symbols in the time domain, The user equipment executes a selection step between the first type of feedback transmission and the second type of feedback transmission, and the selection step is based on a criterion related to the detected transmission or the intended transmission. A user equipment.

13. The criterion is, a) The user equipment detecting the presence of a transmission overlapping at least one of the first type of time - frequency resources, and / or b) The user equipment intending to perform data transmission in at least one of the first type of time - frequency resources, Regarding the user equipment according to Claim 12.

14. A user equipment configured to receive the feedback transmission from the user equipment according to claim 12 or 13, regardless of whether the feedback transmission is of the first type or the second type.

15. Detect an indication from the type of received feedback transmission, and based on the detected indication, the first subcarrier spacing SCS １ Regarding N １ ×L １ The user equipment according to claim 14, further configured to select a group of time-frequency units for further data transmission from a set of N ×L time-frequency units.

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