Working method of receiver and receiving device

Abstract

The invention relates to a working method of a receiver and a receiving device. In an embodiment, each reference signal set, which is a first to M-th (M is a natural number greater than 2) sub-channel for at least one orthogonal frequency division multiplexing symbol, is transmitted through at least one of the at least one orthogonal frequency division multiplexing symbol, the present invention relates to a method for operating a receiver in a communication system in which a plurality of reference signals, which are cyclically shifted on respective sub-channels, are applied, said method comprising: a step of generating at least one received reference signal set corresponding to said first sub-channel on the basis of a received signal; a step of calculating a channel impulse response of the first sub-channel on the basis of at least one set of received reference signals corresponding to the generated first sub-channel; and a step of estimating a cyclic shift corresponding to the first sub-channel on the basis of the calculated channel impulse response of the first sub-channel.

Description

Technical Field

[0001] The present disclosure relates to a received signal processing technology in a communication system, and in particular, some embodiments relate to a technology for effectively detecting the Physical Sidelink Control Channel (PSCCH) of a cellular vehicle-to-everything (C-V2X) network by using cyclic shift estimation based on an inverse discrete Fourier transform (IDFT). Background Art

[0002] In order to achieve autonomous driving of a car, it is necessary to accurately collect information about the vehicle's surroundings and control the vehicle based on this information. Methods for collecting information include methods such as direct detection of the surroundings by cameras, radars, and lidars belonging to the Advanced Driver Assistance System (ADAS), and vehicle-to-everything communication (V2X) technology that shares the information collected in the above manner with surrounding vehicles through wireless communication. To this end, international standards such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11p, known as dedicated short-range communication (DSRC), or the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) sidelink (SL) and new radio (NR) sidelink have been developed, and related research and implementation are being actively carried out.

[0003] The Long Term Evolution Sidelink (LTE SL) and New Radio Sidelink (NR Sl) standards define that the overall bandwidth is divided into a maximum of 20 and 27 subchannels, respectively, and each subchannel can realize peer-to-peer communication with different vehicles. Each subchannel consists of a physical sidelink control channel (PSCCH) containing control information and a physical sidelink shared channel (PSSCH) containing a transport block (TB). It is also defined that each terminal attempts to receive all possible physical sidelink control channel (PSCCH) candidates, but only receives the physical sidelink shared channel (PSSCH) corresponding to the successfully received physical sidelink control channel (PSCCH).

[0004] Therefore, efficient reception signal processing techniques, such as techniques for efficiently detecting physical sidelink control channel (PSCCH) candidates, may be required. Summary of the Invention

[0005] Technical problem to be solved by the invention

[0006] Therefore, efficient receive signal processing techniques (eg, techniques for efficiently detecting a large number of physical sidelink control channel (PSCCH) candidates) may be needed.

[0007] Solutions for solving technical problems

[0008] One form of the present disclosure provides a working method of a receiver in a communication system in which at least one orthogonal frequency division multiplexing (OFDM) symbol - each reference signal set of first to Mth (M is a natural number greater than 2) subchannels is transmitted through at least one of the at least one orthogonal frequency division multiplexing (OFDM) symbol, and the reference signal set includes multiple reference signals with cyclic shifts applied on the corresponding subchannel - is transmitted. The working method includes: a step of generating at least one received reference signal set corresponding to the first subchannel based on a received signal - the received reference signal set respectively includes received reference signals received through the corresponding orthogonal frequency division multiplexing (OFDM) symbol and the first subchannel; a step of calculating a channel impulse response of the first subchannel based on the at least one received reference signal set corresponding to the generated first subchannel; and a step of estimating a cyclic shift corresponding to the first subchannel based on the calculated channel impulse response of the first subchannel.

[0009] In some embodiments, the step of generating at least one received reference signal set may include: extracting at least one sample set corresponding to the symbol body of the at least one orthogonal frequency division multiplexing (OFDM) symbol from the received signal; applying discrete Fourier transform (DFT) to the at least one extracted sample set to generate at least one frequency domain signal; and extracting the received reference signals respectively contained in at least one received reference signal set corresponding to the first subchannel from the at least one generated frequency domain signal.

[0010] In some embodiments, the step of calculating the channel impulse response may include: the step of generating time domain signals corresponding to the at least one received reference signal set respectively; and the step of calculating the channel impulse response based on the at least one generated time domain signal.

[0011] In some embodiments, the step of generating at least one time domain signal may include: applying descrambling to each of the at least one received reference signal sets to generate at least one descrambled symbol set; and applying an inverse discrete Fourier transform (IDFT) to each of the at least one descrambled symbol set to generate the at least one time domain signal. In some embodiments, the size of the IDFT may be four times the size of the IDFT object, i.e., the descrambled symbol set. In some embodiments, the size of the IDFT may be greater than or equal to the size of the IDFT object, i.e., the descrambled symbol set, and the step of applying the IDFT may include: aligning the center of the IDFT object, i.e., the descrambled symbol set, to the center of the IDFT window and applying the IDFT.

[0012] In some embodiments, the reference signal set of the first subchannel can be transmitted via an orthogonal frequency division multiplexing (OFDM) symbol, and the step of generating at least one received reference signal set may include: a step of generating a received reference signal set corresponding to the first subchannel; the step of generating at least one time domain signal may include: a step of generating a time domain signal corresponding to the generated received reference signal set; and the step of calculating the channel impulse response may include: a step of determining the generated time domain signal as the channel impulse response.

[0013] In some embodiments, the reference signal set of the first subchannel can be transmitted through multiple orthogonal frequency division multiplexing (OFDM) symbols, and the step of generating at least one received reference signal set may include: the step of generating multiple received reference signal sets corresponding to the first subchannel; the step of generating at least one time domain signal may include: the step of generating time domain signals corresponding to the multiple generated received reference signal sets respectively; and the step of calculating the channel impulse response may include: the step of summing the time domain samples respectively contained in the multiple generated time domain signals according to the same time index, thereby calculating the channel impulse response.

[0014] In some embodiments, the step of estimating the cyclic shift may include: detecting a time index having a maximum value among time domain samples of the channel impulse response; and estimating the cyclic shift corresponding to each of the at least one subchannel based on the detected time index. In some embodiments, the step of estimating the cyclic shift may include estimating the cyclic shift based on an interval to which the time index having the maximum value of the channel impulse response belongs among a plurality of intervals; the plurality of intervals may be intervals obtained by dividing the time domain interval of the channel impulse response based on statistical characteristics of the channel impulse response when given cyclic shifts corresponding to the M subchannels. In some embodiments, the statistical characteristics of the channel impulse response may form a sinc function centered around each of the plurality of intervals.

[0015] In some embodiments, the method may further include: estimating a timing offset based on the estimated channel impulse response. In some embodiments, the step of estimating a cyclic shift may include estimating a cyclic shift corresponding to each of the at least one subchannel based on a time index having a maximum value among time-domain samples of the channel impulse response; and the step of estimating a timing offset may include estimating the timing offset based on a ratio between a size of a discrete Fourier transform (DFT) used when generating the at least one receive reference signal set and a size of an inverse discrete Fourier transform (IDFT) used when calculating the channel impulse response, the time index having the maximum value, and the estimated cyclic shift.

[0016] In some embodiments, the method may further include: for each m (the value of m is 2 to M), generating at least one received reference signal set corresponding to the mth subchannel based on the received signal - the received reference signal set respectively includes received reference signals received through corresponding orthogonal frequency division multiplexing (OFDM) symbols and the mth subchannel; the step of calculating the channel impulse response of the mth subchannel based on the at least one received reference signal set corresponding to the generated mth subchannel; and the step of estimating the cyclic shift corresponding to the mth subchannel based on the calculated channel impulse response of the mth subchannel.

[0017] In some embodiments, the first to Mth subchannels may respectively include the physical sidelink control channel (PSCCH) and the physical sidelink shared channel (PSSCH) of the long term evolution (LTE) side link, and the reference signal sets of the first to Mth subchannels may respectively include the reference signal sets of the physical sidelink control channel (PSCCH) contained in the corresponding subchannels.

[0018] In some embodiments, the first to Mth subchannels may respectively include the physical sidelink control channel (PSCCH) and the physical sidelink shared channel (PSSCH) of the new radio (NR) side link, and the reference signal sets of the first to Mth subchannels may respectively include the reference signal sets of the physical sidelink control channel (PSCCH) contained in the corresponding subchannels.

[0019] Another form of the present disclosure provides a receiving device, as a receiving device in a communication system for transmitting at least one orthogonal frequency division multiplexing (OFDM) symbol - each reference signal set of the first to Mth (M is a natural number greater than 2) subchannels is transmitted through at least one of the at least one orthogonal frequency division multiplexing (OFDM) symbol, and the reference signal set includes multiple reference signals with cyclic shifts applied on the corresponding subchannels. The receiving device includes: a receiving reference signal set generation block, which generates at least one receiving reference signal set corresponding to the first subchannel based on the received signal - the receiving reference signal set respectively includes receiving reference signals received through the corresponding orthogonal frequency division multiplexing (OFDM) symbol and the first subchannel; a channel impulse response calculation block, which calculates the channel impulse response of the first subchannel based on the at least one receiving reference signal set corresponding to the generated first subchannel; and a cyclic shift estimation block, which estimates the cyclic shift corresponding to the first subchannel based on the calculated channel impulse response of the first subchannel.

[0020] In some embodiments, the received reference signal set generation block may include: a sample set extraction block, which extracts at least one sample set corresponding to the symbol body of the at least one orthogonal frequency division multiplexing (OFDM) symbol from the received signal; a discrete Fourier transform (DFT) block, which applies discrete Fourier transform (DFT) to the at least one extracted sample set, thereby generating at least one frequency domain signal; and a received reference signal extraction block, which extracts the received reference signals respectively contained in the at least one received reference signal set corresponding to the first subchannel from the at least one generated frequency domain signal.

[0021] In some embodiments, the channel impulse response calculation block may include: a time domain signal generation block, which generates time domain signals corresponding to the at least one received reference signal set respectively; and a calculation block, which calculates the channel impulse response based on the at least one generated time domain signal.

[0022] In some embodiments, the time domain signal generation block may include: a descrambling block, applying descrambling to the at least one received reference signal set respectively, thereby generating at least one descrambling result symbol set; and an inverse discrete Fourier transform (IDFT) block, applying an inverse discrete Fourier transform (IDFT) to the at least one generated descrambling result symbol set respectively, thereby generating the at least one time domain signal.

[0023] In some embodiments, the cyclic shift estimation block may include: a detection block, detecting a time index having a maximum value in the time domain samples of the channel impulse response; and an estimation block, estimating the cyclic shift corresponding to each of the at least one subchannel based on the detected time index.

[0024] In some embodiments, the receiving apparatus may further include: a timing offset estimation block for estimating the timing offset based on the estimated channel impulse response.

[0025] In some embodiments, the received reference signal set generation block can generate, for each m (the value of m is 2 to M), at least one received reference signal set corresponding to the mth subchannel based on the received signal - the received reference signal set respectively includes received reference signals received through corresponding orthogonal frequency division multiplexing (OFDM) symbols and the mth subchannel -, the channel impulse response calculation block can calculate the channel impulse response of the mth subchannel based on the at least one received reference signal set corresponding to the generated mth subchannel, and the cyclic shift estimation block can estimate the cyclic shift corresponding to the mth subchannel based on the calculated channel impulse response of the mth subchannel.

[0026] In some embodiments, the first to Mth subchannels may respectively include the physical sidelink control channel (PSCCH) and the physical sidelink shared channel (PSSCH) of the long term evolution (LTE) side link, and the reference signal sets of the first to Mth subchannels may respectively include the reference signal sets of the physical sidelink control channel (PSCCH) contained in the corresponding subchannels.

[0027] In some embodiments, the first to Mth subchannels may respectively include the physical sidelink control channel (PSCCH) and the physical sidelink shared channel (PSSCH) of the new radio (NR) side link, and the reference signal sets of the first to Mth subchannels may respectively include the reference signal sets of the physical sidelink control channel (PSCCH) contained in the corresponding subchannels.

[0028] Yet another aspect of the present disclosure provides a storage medium as a non-volatile storage medium for storing instructions readable by a processor of an electronic device, wherein the instructions may cause the processor to execute embodiments of the present disclosure.

[0029] This summary is intended only to introduce, in simplified form, selected concepts from those further described in the detailed description that follows. This summary is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve some or all of the problems mentioned in any part of this specification. In addition to the exemplary aspects, embodiments, and features described above, further aspects, embodiments, and features will be further clarified by reference to the detailed description and accompanying drawings that follow.

[0030] Effects of the Invention

[0031] Some embodiments of the present disclosure can achieve the following advantages, but not all embodiments necessarily include all the advantages, and thus the scope of the claims of the present disclosure should not be construed as being limited thereby.

[0032] In some embodiments, the cyclic shift and the timing offset may be simultaneously calculated using an inverse discrete Fourier transform (IDFT) of a physical sidelink control channel demodulation reference signal (PSCCH DMRS).

[0033] In some embodiments, a cyclic shift estimation technique may be provided that can ensure excellent cyclic shift estimation performance even in an environment with a large timing offset.

[0034] In some embodiments, a cyclic shift estimation technique that minimizes additional logic may be provided by reusing existing logic (eg, logic to find the timing offset).

[0035] In some embodiments, reception attempts on a large number of physical sidelink control channel (PSCCH) candidates can be effectively reduced through excellent cyclic shift detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 An Orthogonal Frequency Division Multiplexing (OFDM) symbol generation block is illustrated in .

[0037] Figure 2 An Orthogonal Frequency Division Multiplexing (OFDM) symbol is illustrated in .

[0038] Figure 3 The 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) frame structure is illustrated in FIG.

[0039] Figure 4 The resource grid of the Long Term Evolution (LTE) side link is illustrated in FIG.

[0040] Figure 5 The resource grid of the New Radio Side Link (NR SL) is illustrated in FIG.

[0041] Figure 6 as well as Figure 7 The various long term evolution side link (LTE SL) subframe structures and new radio side link (NR SL) subframe structures are illustrated in FIG.

[0042] Figure 8 This is a schematic diagram of the demodulation reference signal resource elements (DMRS REs) included in the physical side link control channel (PSCCH) of the new radio side link (NR SL).

[0043] Figure 9is a block diagram illustrating some embodiments of received signal processing.

[0044] Figure 10 is pseudocode illustrating some embodiments for estimating a cyclic shift used in a physical sidelink control channel demodulation reference signal (PSCCH DMRS) from an inverse discrete Fourier transform (IDFT) result.

[0045] Figure 11 exemplifies the channel impulse response (CIR) when there is no timing offset in Long Term Evolution Sidelink (LTE SL).

[0046] Figure 12 , the channel impulse response (CIR) when there is a timing offset in the Long Term Evolution Side Link (LTE SL) is illustrated.

[0047] Figure 13 The channel impulse response (CIR) when there is no timing offset in the new radio side link (NR SL) is illustrated in FIG.

[0048] Figure 14 The figure illustrates the channel impulse response (CIR) when there is a timing offset in the new radio side link (NR SL).

[0049] Figure 15 is a graph illustrating the performance of the disclosed cyclic shift estimation technique in Long Term Evolution Sidelink (LTE SL).

[0050] Figure 16 14.2-1 of the 3rd Generation Partnership Project standard document (3GPP 36.101) that specifies performance requirements related to timing offset and frequency offset in Long Term Evolution Sidelink (LTE SL) is shown in FIG.

[0051] Figure 17 FIG shows Table 14.2-2 of the 3rd Generation Partnership Project standard document (3GPP 36.101) which specifies the performance requirements for the Long Term Evolution Side Link (LTE SL).

[0052] Figure 18 is a graph illustrating the performance of the disclosed cyclic shift estimation technique in Long Term Evolution Sidelink (NR SL).

[0053] Figure 19 The performance requirements in the new radio side link (NR SL) are illustrated in FIG. DETAILED DESCRIPTION

[0054] The description of the present invention is merely an example of an embodiment for illustrating its structure and even function, and therefore should not be interpreted as limiting the scope of the claims of the present invention to the examples described herein. That is, because the examples can be modified in various ways and have various forms, the scope of the claims of the present invention should be understood to include equivalents that can implement the technical ideas thereof. Furthermore, the objects and effects set forth in the present invention do not necessarily mean that a particular embodiment must include all of them or only include the described effects, and therefore should not be interpreted as limiting the scope of the claims of the present invention.

[0055] Furthermore, the meanings of the terms used in the present disclosure should be construed in the following manner.

[0056] Terms such as "first" and "second" are merely used to distinguish one component from other components, and the scope of the claims of the present invention is not limited to these terms. For example, a first component can be named a second component, and similarly, a second component can be named a first component.

[0057] When a component is described as being "connected" to another component, it may be directly connected to the other component, but it should be understood that other components may exist between the two components. Conversely, when a component is described as being "directly connected" to another component, it should be understood that no other components exist between the two components. In addition, other expressions used to describe the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to", should be interpreted in the same manner.

[0058] Unless the context clearly indicates otherwise, singular statements should be understood to include plural meanings, and terms such as "including" or "having" are only used to indicate the existence of the implemented features, numbers, steps, actions, constituent elements, parts or the combination thereof, and should be understood as not excluding in advance the possibility that one or more other features, numbers, steps, actions, constituent elements, parts or the combination thereof may exist or be added.

[0059] In each step, identification numbers (e.g., a, b, and c) are used only for convenience of description and do not indicate the order of the steps. Unless the context clearly indicates a specific order for the steps, the steps may be performed in a different order than that described. In other words, the steps may be performed in the same order as described, substantially simultaneously, or in reverse order.

[0060] Figure 1 An Orthogonal Frequency Division Multiplexing (OFDM) symbol generation block is illustrated in .

[0061] Orthogonal Frequency Division Multiplexing (OFDM) Figure 1 As shown, this is a method of dividing the data to be transmitted into multiple small data and modulating them into mutually orthogonal subcarriers through inverse fast Fourier transform (IFFT) and then transmitting them simultaneously.

[0062] Figure 2 An Orthogonal Frequency Division Multiplexing (OFDM) symbol is illustrated in .

[0063] Orthogonal frequency division multiplexing (OFDM) Figure 2 As shown, it can be composed of a cyclic prefix (CP) and a transmission signal body (symbol body). Multipath interference can be alleviated by adding a certain portion of the rear side of the multi-carrier transmission signal (i.e., the interval corresponding to the cyclic prefix interval in the symbol body, hereinafter referred to as the cyclic prefix corresponding interval) to the front side cyclic prefix (CP). In the 3rd Generation Partnership Project Long Term Evolution / New Radio (3GPP LTE / NR), it has been specified that the basic time unit (basic time unit) T s The symbol main interval N is the benchmark c =2048T s When N in the normal cyclic prefix (CP) g =144T s or 160T s , and N in the extended cyclic prefix (CP) g =512T s .

[0064] As described above, the combination of a cyclic prefix (CP) and the main body of the output signal is called cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM), and the cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM) is used in the 3rd Generation Partnership Project Long Term Evolution / New Radio (3GPP LTE / NR) side link.

[0065] Figure 3 The 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) frame structure is illustrated in FIG.

[0066] Frames in the 3rd Generation Partnership Project Long Term Evolution / New Radio (3GPP LTE / NR) are as follows: Figure 3As shown, on the time axis, it can be composed of a time unit (such as a subframe or time slot, etc.) including multiple orthogonal frequency division multiplexing (OFDM) symbols, and on the frequency axis, it can be composed of a resource block (RB) including multiple (such as 12) subcarriers.

[0067] Figure 4 The resource grid of the long term evolution (LTE) sidelink (SL) is illustrated in FIG.

[0068] In the Long Term Evolution Side Link (LTE SL), Figure 4 As shown, the physical sidelink control channel can be used to control the sidelink control information (SCI) consisting of two resource blocks (RBs).

[0069] (PSCCH) and contains The physical side link shared channel (PSSCH) is composed of a pair of transport blocks (RBs) to perform point-to-point communication. At this time, the physical side link shared channel (PSSCH) can change its size by allocating one or more subchannels. The physical side link control channel (PSCCH) and the physical side link shared channel (PSSCH) can be based on the upper control signal (RRC message) in the following way: Figure 4 The left figure (a) shows the adjacent structure, or the Figure 4 As an example, in the non-adjacent structure shown in the right figure (b) Figure 4 In the left figure (a), the topmost block among the shaded blocks may correspond to the physical sidelink control channel (PSCCH), and the remaining blocks may correspond to the physical sidelink shared channel (PSSCH). As another example, Figure 4 The uppermost shaded block in the right figure (b) may correspond to the physical sidelink control channel (PSCCH), while the shaded blocks separated from the uppermost shaded block and located to its lower side (i.e., other frequency domains within the same orthogonal frequency division multiplexing (OFDM) symbol) may correspond to the physical sidelink shared channel (PSSCH).

[0070] Figure 5 The resource grid of the New Radio Side Link (NR SL) is illustrated in FIG.

[0071] New Radio Side Link (NR SL) Figure 5As shown in FIG, a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) can be allocated to one or more subchannels. However, unlike long-term evolution (LTE), the sidelink control signal (SCI) is composed of two stages, and the physical sidelink control channel (PSCCH) and the physical sidelink shared channel (PSSCH) are adjacent to each other. As an example, Figure 5 The white box marked with a dotted line is included in the physical sidelink control channel (PSCCH) as the sidelink control signal (SCI) of the first stage, and the shaded box marked with a dotted line is included in the physical sidelink shared channel (PSSCH) as the sidelink control signal (SCI) of the second stage, and the solid box including the white box marked with a dotted line and the shaded box marked with a dotted line can include the data of the physical sidelink shared channel (PSSCH) in the remaining resource elements except the white box marked with a dotted line and the shaded box marked with a dotted line.

[0072] Figure 6 as well as Figure 7 The various long term evolution side link (LTE SL) subframe structures and new radio side link (NR SL) subframe structures are illustrated in FIG.

[0073] Figure 8 This is a schematic diagram of the demodulation reference signal resource elements (DMRS REs) included in the physical side link control channel (PSCCH) of the new radio side link (NR SL).

[0074] Long Term Evolution Side Link (LTE SL) Figure 6 As shown in FIG, a subframe can be used as an orthogonal frequency division multiplexing (OFDM) symbol including four demodulation reference signal (DMRS) symbols and data symbols. Figure 6 , it can be confirmed that the Orthogonal Frequency Division Multiplexing (OFDM) symbol corresponding to the Demodulation Reference Signal (DMRS) symbol is composed of the Physical Side Link Shared Channel Demodulation Reference Signal (PSSCH DMRS) and the Physical Side Link Control Channel Demodulation Reference Signal (PSCCH DMRS) in the frequency domain. In addition, refer to Figure 6 It can be confirmed that the orthogonal frequency division multiplexing (OFDM) symbol corresponding to the data symbol is composed of a physical side link control channel (PSCCH) data signal and a physical side link shared channel (PSSCH) data signal in the frequency domain.

[0075] In the New Radio Side Link (NR SL), the number of Demodulation Reference Signal (DMRS) symbols can be changed through higher-level control signals. Figure 7, the second to fourth Orthogonal Frequency Division Multiplexing (OFDM) symbols include the Physical Sidelink Control Channel (PSCCH), and as Figure 8 As shown, the corresponding physical sidelink control channel (PSCCH) may include a physical sidelink control channel (PSCCH) data signal and a physical sidelink control channel demodulation reference signal (PSCCH DMRS) in the corresponding frequency domain. Figure 7 , an orthogonal frequency division multiplexing (OFDM) symbol marked as a physical sidelink shared channel demodulation reference signal (PSSCH DMRS) can contain a physical sidelink shared channel demodulation reference signal (PSSCH DMRS) and a physical sidelink shared channel (PSSCH) data signal in the frequency domain.

[0076] The last symbol of the subframe that exists in both the Long Term Evolution Side Link (LTE SL) and the New Radio Side Link (NR Sl) belongs to the guard period, which stipulates that no signal is transmitted during the period.

[0077] Long Term Evolution (LTE) side link and New Radio (NR) side link such as Figures 4 and 5 As shown, the entire bandwidth can be divided into multiple (for example, M = N sub In this specification, M and N are sub It is a symbol representing the number of subchannels. For the convenience of explanation, it will be used interchangeably (for example, M is used in narrative expressions, and N is used in expressions related to mathematical formulas). sub ).

[0078] Each sub-channel is Figures 4 to 8 As shown, it can be composed of a physical sidelink control channel (PSCCH) containing control information and a physical sidelink shared channel (PSSCH) containing transport blocks (TBs).

[0079] The demodulation reference signal (SMRS) used in channel estimation for the physical sidelink control channel (PSCCH) is a known signal with a fixed amplitude but potentially varying phase in the frequency domain. The demodulation reference signal (DMRS) is defined differently in the Long Term Evolution Sidelink (LTE SL) and New Radio Sidelink (NR SL), as follows.

[0080] Long Term Evolution Sidelink Demodulation Reference Signal (LTE SL DMRS) Figure 6As shown in Figure 1, there are four demodulation reference signal (OFDM) symbols and two resource blocks (RBs). All resource elements (REs) located on the corresponding resource blocks (RBs) are demodulation reference signals (DMRS). The long-term evolution sidelink demodulation reference signal (LTE SLDMRS) is shown in Mathematical Formula 1. It can be obtained by combining the basic reference signal d(k) with the cyclic shift n cs The linear phase of the multiplication is then transmitted. Cyclic shift n cs The value of can be 0, 3, 6 or 9, and can be arbitrarily selected by the sending user equipment (UE).

[0081]

Mathematical formula 1

[0082]

[0083] New radio link demodulation reference signal (NR SL DMRS) Figure 7 as well as Figure 8 As shown, there are two or three demodulation reference signal (OFDM) symbols and On a resource block (RB), in the corresponding resource block (RB), only one resource element (RE) out of every four resource elements (RE) is a demodulation reference signal (DMRS). The new radio link demodulation reference signal (NR SL DMRS) is shown in Mathematical Formula 2. It can be obtained by combining the basic reference signal d(k) with the linear phase w defined by Mathematical Formula 3. f,i After multiplication, the signal is transmitted. In Equation 3, i can be arbitrarily selected by the transmitting user equipment (UE) from 0, 1, and 2. Similar to the long-term evolution sidelink demodulation reference signal (LTE SL DMRS), the new radio sidelink demodulation reference signal (NR SL DMRS) can also be considered a signal to which a cyclic shift is applied because a linear phase is multiplied by the basic reference signal.

[0084]

Mathematical formula 2

[0085]

[0086]

Mathematical formula 3

[0087]

[0088] Because the receiving user equipment (UE) cannot know in advance which cyclic shift the transmitting user equipment (UE) uses for transmission, it is necessary to try to receive each cyclic shift candidate for each physical sidelink control channel (PSCCH). Therefore, there can be 4N in the long-term evolution sidelink (LTE SL). subThere are 3N physical side link control channel (PSCCH) candidates, and in the new radio side link (NR SL) there can be 3N sub Physical Sidelink Control Channel (PSCCH) candidates exist.

[0089] Some embodiments of the present disclosure relate to a technique that can reduce the number of reception attempts by estimating a cyclic shift before receiving a physical sidelink control channel (PSCCH) by a receiving user equipment (UE).

[0090] When the discrete Fourier transform (DFT) result of the time domain signal x[n] of the cyclic prefix-demodulation reference signal (CP-OFDM) is X[k], x[((n-τ)) with a timing offset τ N The discrete Fourier transform (DFT) result of ] can be That is, the timing offset is the same as the cyclic shift of the physical sidelink control channel demodulation reference signal (PSCCH DMRS) applicable to the long-term evolution / new air interface side link (LTE / NR SL), which will produce a linear phase in the frequency domain that is proportional to the subcarrier index k.

[0091] As described above, in the vehicle-to-everything (V2X) side link (SL), the receiving user equipment (UE) needs to make reception attempts on a large number of physical side link control channel (PSCCH) candidates. In addition, vehicle-to-everything (V2X) communications require lower processing delays in order to transmit emergency data such as preventing collisions between vehicles. Therefore, in order to meet the lower processing delay requirement, a technology that can reduce the number of reception attempts on the physical side link control channel (PSCCH) candidates may be needed. Some embodiments of the present disclosure relate to a technology that can reduce the number of reception attempts on the physical side link control channel (PSCCH) candidates in order to meet the lower processing delay requirement.

[0092] In addition, in vehicle-to-everything (V2X) communications, because vehicles communicate directly with each other through peer-to-peer communication, the imperfect local oscillator of the vehicle's transceiver itself will cause synchronization errors (or timing offsets) and frequency errors (or frequency offsets) in each peer-to-peer communication, which may require correction of the corresponding errors in each peer-to-peer communication. In the 3rd Generation Partnership Project (3GPP) standard documents (3GPP 36.101 and 38.101), as a performance requirement, the timing offset between vehicles is defined as the maximum allowable T g / 2-12T sIn this document, in order to reduce the number of physical sidelink control channel (PSCCH) candidates that require reception attempts even in an environment with a large timing offset as described above, a technology that can effectively estimate the cyclic shift applicable in the demodulation reference signal (DMRS) may be required. Some embodiments of the present disclosure relate to a technology that can effectively estimate the cyclic shift even in an environment with a large timing offset.

[0093] Previous studies for reducing physical sidelink control channel (PSCCH) reception attempts include blind decoding (BD) technology and sensing based algorithm (SALG) technology.

[0094] Blind decoding (BD) measures the Reference Signal Received Power (RSRP) for each cyclic shift and prioritizes reception attempts for cyclic shifts with the highest RSRP. If the signal processed by the prioritized cyclic shift passes subsequent checks (such as the Cyclic Redundancy Check (CRC)), reception attempts for lower-priority cyclic shifts (e.g., those with poor RSRP) are omitted, thereby reducing the overall number of reception attempts.

[0095] The Sensing-Based Algorithm (SALG) technology is a technology that calculates the correlation between the phase of each cyclic shift and the received demodulation reference signal (DMRS), and attempts to receive the corresponding physical sidelink control channel (PSCCH) based on the signal processed according to the cyclic shift with the larger correlation value.

[0096] However, both of the above-mentioned technologies need to rely on the correlation between the linear phase according to the cyclic shift and the demodulation reference signal (DMRS). Therefore, when the timing offset is large, the correlation may be reduced, resulting in the disadvantage of incorrectly estimating the cyclic shift.

[0097] Figure 9 is a block diagram illustrating some embodiments of received signal processing.

[0098] Figure 10 is a pseudo code for illustrating some embodiments of estimating the cyclic shift used in the physical sidelink control channel demodulation reference signal (PSCCH DMRS) from the inverse discrete Fourier transform (IDFT) result. As an example, Figure 10Some embodiments of the present invention include an embodiment consisting of five steps of estimating a cyclic shift applicable in a physical sidelink control channel demodulation reference signal (PSCCH DMRS) using an inverse discrete Fourier transform (IDFT) result used in timing offset estimation.

[0099] In some embodiments, as Figure 9 As shown, the receiving apparatus 900 may include at least a portion of a reception reference signal set generation block 910 , a channel impulse response (CIR) calculation block 920 , a cyclic shift estimation block 930 , and a timing offset estimation block 940 .

[0100] In some embodiments, the receiving device 900 may further include Figure 9 As an example, the receiving apparatus 900 may further include a module for performing a reception attempt (e.g., a cyclic repetition check (CRC) test) on a corresponding physical sidelink control channel (PSCCH) based on the estimation information obtained by the cyclic shift estimation block 930 and / or the timing offset estimation block 940.

[0101] In some embodiments, the receiving apparatus 900 may correspond to a receiver in a communication system based on orthogonal frequency division multiplexing (OFDM) symbols. As an example, the receiving apparatus 900 may correspond to a receiving user equipment (UE) in a vehicle-to-everything (V2X) system.

[0102] In some embodiments, a communication system based on orthogonal frequency division multiplexing (OFDM) symbols may transmit at least one orthogonal frequency division multiplexing (OFDM) symbol via a wireless channel and receive the symbol via the wireless channel. In some embodiments, a reference signal set for each of the first through Mth (M is a natural number greater than or equal to 2) subchannels may be transmitted via at least one of the at least one orthogonal frequency division multiplexing (OFDM) symbol. In some embodiments, the reference signal set may include multiple reference signals to which cyclic shifts corresponding to the corresponding subchannels are applied.

[0103] In some embodiments, the multiple subchannels may include multiple physical sidelink control channels (PSCCHs) of a long term evolution (LTE) sidelink, and the reference signals may respectively include demodulation reference signals for the multiple physical sidelink control channels (PSCCHs).

[0104] In some embodiments, the multiple subchannels may include multiple physical sidelink control channels (PSCCHs) of the new radio (NR) sidelink, and the reference signal may include demodulation reference signals for the multiple physical sidelink control channels (PSCCHs), respectively.

[0105] In some embodiments, the first to Mth sub-channels described above may correspond to Figure 10 Subchannel index c in = 0 to N sub The subchannel corresponds to -1.

[0106] In some embodiments, at least one OFDM symbol may be a plurality of OFDM symbols. As an example, the plurality of OFDM symbols may be associated with a plurality of OFDM symbols corresponding to Figure 10 The symbol index l in = 0 to In this case, as described later, a signal corresponding to a plurality of orthogonal frequency division multiplexing (OFDM) signals ( Figure 10 ix in the middle c，l ) of the summation work (e.g. Figure 10 Step 3 in the previous step).

[0107] In some other embodiments, at least one orthogonal frequency division multiplexing (OFDM) symbol may be an orthogonal frequency division multiplexing (OFDM) symbol. As an example, at least one of the first to Mth subchannels described above may transmit a demodulation reference signal of the corresponding subchannel via an orthogonal frequency division multiplexing (OFDM) symbol, or the receiver may use only one of the at least one orthogonal frequency division multiplexing (OFDM) symbol to perform the reception signal processing work of some embodiments of the present disclosure. In such a case, as described later, the summing work (e.g., Figure 10 Instead of step 3) in , cyclic shift estimation is performed based on a signal corresponding to one Orthogonal Frequency Division Multiplexing (OFDM) symbol.

[0108] Part of the following description discloses some embodiments mainly based on the processing process related to the first sub-channel, but the corresponding embodiments can also be applied to the processing process of other sub-channels (such as the second to M-th sub-channels). As an example, Figure 10 As shown, the corresponding work can be performed with the subchannel index c ranging from 0 to N sub Repeat within the range of -1.

[0109] In some embodiments, the received reference signal set generation block 910 may generate at least one received reference signal set corresponding to the first subchannel based on the received signal. In some embodiments, the at least one received reference signal set may include received reference signals received via corresponding orthogonal frequency division multiplexing (OFDM) symbols and the first subchannel, respectively.

[0110] In some embodiments, the channel impulse response (CIR) calculation block 920 may calculate the channel impulse response (CIR) of the first subchannel based on at least one received reference signal set corresponding to the first subchannel generated in the received reference signal set generation block 910 .

[0111] In some embodiments, the cyclic shift estimation block 930 may estimate the cyclic shift corresponding to the first subchannel based on the channel impulse response of the first subchannel calculated in the channel impulse response (CIR) calculation block 920 .

[0112] In some embodiments, as Figure 9 As shown, the received reference signal set generation block 910 may include a sample set extraction block 912 , a discrete Fourier transform (DFT) block 914 , and a received reference signal extraction block 916 .

[0113] In some embodiments, the sample set extraction block 912 may extract at least one sample set respectively corresponding to a symbol body of at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol from the received signal.

[0114] In some embodiments, the discrete Fourier transform (DFT) block 914 may apply a discrete Fourier transform (DFT) to each of the at least one sample set extracted in the sample set extraction block 912 to generate at least one frequency domain signal.

[0115] The applicable results of discrete Fourier transform (DFT), ie, each frequency domain signal, may include a received demodulation reference symbol r(k) represented by equation 4. Equation 4 can be derived from equations 1 and 2 and a linear phase according to a timing offset.

[0116]

Mathematical formula 4

[0117] r(k)=H·s(k)=H·d(k)exp(j2πεk / N)exp(-j2πτk / N)=H·d(k)exp(j2π(ε-τ)k / N)

[0118] In Equation 4, H is the channel response. To make the formula clearer, the channel response is assumed to be a one-tap response. However, some embodiments of the present disclosure can also be applied to other channel responses that are not one-tap responses according to the same principles.

[0119] In Math 4, ε represents a cyclic shift that scales the inverse fast Fourier transform (IFFT) size N, and τ represents a timing offset that scales the inverse fast Fourier transform (IFFT) size N.

[0120] In some embodiments, the received reference signal extraction block 916 may extract received reference signals respectively included in at least one received reference signal set corresponding to the first subchannel from at least one frequency domain signal generated by the discrete Fourier transform (DFT) block 914 .

[0121] In some embodiments, as Figure 9 As shown, the channel impulse response (CIR) calculation block 920 may include a time domain signal generation block 922 and a calculation block 928 .

[0122] In some embodiments, the time domain signal generation block 922 may generate time domain signals respectively corresponding to at least one receive reference signal set corresponding to the first subchannel generated in the receive reference signal set generation block 910 .

[0123] In some embodiments, the calculation block 928 may calculate a channel impulse response of the first subchannel based on the at least one time domain signal generated in the time domain signal generation block 922 .

[0124] In some embodiments, as Figure 9 As shown, the time domain signal generation block 922 may include a descrambling block 924 and an inverse discrete Fourier transform (IDFT) block 926 .

[0125] In some embodiments, the descrambling block 924 may apply descrambling to at least one received reference signal set corresponding to the first subchannel generated in the received reference signal set generation block 910 , thereby generating at least one descrambled result symbol set.

[0126] As described above, the phase of each demodulation reference signal (DMRS) in the demodulation reference signal (DMRS) may be different from each other, but because it is a known signal with a certain size, the receiving end can use it in channel estimation after compensating the phase of the demodulation reference signal (DMRS) and converting it into a state with a certain size and phase. Based on the same principle, the descrambling block 924 is as follows Figure 10 As shown in step 1) of FIG, the descrambling result signal x can be generated by multiplying the received reference signal with the complex conjugate of the corresponding basic reference signal d(k) respectively. c,i .

[0127] As an example, the number of resource elements (REs) of the physical sidelink control channel (PSCCH) corresponding to subchannel index c in the long term evolution sidelink (LTE SL) is When , the descrambling block 924 may generate a descrambled result symbol set in the manner shown in Math 5. The descrambled result symbol set may include the received reference signal set corresponding to the corresponding subchannel (subchannel index c) contained in the corresponding Orthogonal Frequency Division Multiplexing (OFDM) symbol (symbol index 1). The descrambling result signal x c，l (k).

[0128]

Mathematical formula 5

[0129]

[0130] As another example, since one demodulation reference signal resource element (DMRS RE) exists in every four resource elements (REs) in the new radio side link (NR SL), the descrambling block 924 may generate a descrambling result symbol set represented by Mathematical Formula 6. The descrambling result symbol set may include a descrambling result signal x corresponding to a received reference signal set of a corresponding subchannel (subchannel index c) contained in a corresponding orthogonal frequency division multiplexing (OFDM) symbol (symbol index 1). c，l (k).

[0131]

Mathematical formula 6

[0132]

[0133] In some embodiments, the inverse discrete Fourier transform (IDFT) block 926 may apply an inverse discrete Fourier transform (IDFT) to the at least one descrambled result symbol set generated in the descrambling block 924, respectively, thereby generating the at least one time domain signal.

[0134] In some embodiments, the size of the inverse discrete Fourier transform (IDFT) may be greater than or equal to the size of the inverse discrete Fourier transform (IDFT) object, i.e., the descrambled result symbol set, and the inverse discrete Fourier transform (IDFT) block may configure the center of the inverse discrete Fourier transform (IDFT) object, i.e., the descrambled result symbol set, to the center position of the inverse discrete Fourier transform (IDFT) window and apply the inverse discrete Fourier transform (IDFT).

[0135] In some embodiments, the size of the inverse discrete Fourier transform (IDFT) may be four times the size of the inverse discrete Fourier transform (IDFT) object, ie, the descrambled result symbol set.

[0136] The operation of the Inverse Discrete Fourier Transform (IDFT) block 926 according to some embodiments may be similar to Figure 10Corresponding to step 2 in . Generally speaking, the timing offset is corrected during the channel estimation process, but due to the timing offset estimation error, a linear phase may also exist after the correction. In some embodiments, in order to make the linear phase between the ends of the demodulation reference signal resource element (DMRS RE) on both sides according to the estimated error reach less than π / 4, an inverse discrete Fourier transform (IDFT) size of four times the number of physical side link control channel demodulation reference signal resource elements (PSCCH DMRS RE) can be selected. As an example, because all resource elements (REs) of each demodulation reference signal (DMRS) symbol in the long term evolution side link (LTE SL) are demodulation reference signal resource elements (DMRS RE), it is only when π is selected as the inverse discrete Fourier transform (IDFT) size. As another example, since only one of every four resource elements (REs) in the new radio link (NR SL) is a demodulation reference signal resource element (DMRSRE), it can be used as an inverse discrete Fourier transform (IDFT) size selection. The channel impulse response (CIR) is calculated. Since the IDFT size can be increased or decreased as needed, the IDFT size is denoted as N′ below.

[0137] As an example, in the long term evolution sidelink (LTE SL), the center of the physical sidelink control channel demodulation reference signal resource element (PSCCH DMRS RE) can be configured to the center position of the inverse discrete Fourier transform (IDFT) and an inverse discrete Fourier transform (IDFT) of size N′ can be performed to obtain the channel impulse response (CIR) as shown in Mathematical Formula 7. c，l (n).

[0138]

Mathematical formula 7

[0139]

[0140] Refer to Equation 7, Channel Impulse Response (CIR)ix c，l (n) can be considered as the sinc function occurring on the channel impulse response (CIR) cyclic shift of .

[0141] As another example, since only one demodulation reference signal resource element (DMRS RE) is extracted for every four resource elements (RE) in the new radio side link (NR SL) and an inverse discrete Fourier transform (IDFT) is applied, the channel impulse response (CIR) is ix c，l(n) can be viewed as a sinc function occurring on the channel impulse response (CIR) cyclic shift of .

[0142] As described above, the calculation block 928 may calculate the channel impulse response of the first subchannel based on the at least one time domain signal generated in the time domain signal generation block 922 .

[0143] In some embodiments, when only one time domain signal (eg, ix with l=0) is generated or used, c，l ), the calculation block 928 may determine the corresponding time domain signal as a channel impulse response (CIR).

[0144] In some other embodiments, when generating a plurality of time domain signals (eg, ix c，l , l=0,1,…, ), the calculation block 928 can be Figure 10 The corresponding time domain signals are summed in the manner shown in step 3 in the embodiment and the summation result is determined as the channel impulse response (CIR).

[0145] As an example, the calculation block 928 may calculate the channel impulse response (CIR) by summing the time domain samples respectively contained in the plurality of time domain signals according to the same time index. That is, some embodiments of the calculation block 928 may be similar to Figure 10 As an example, the calculation block 928 is as follows: Figure 10 As shown in step 3 of FIG, lx can be obtained by accumulating the physical side link control channel demodulation reference signal (PSCCH DMRS) symbols. c The accumulation operation described above can reduce noise, thereby improving the accuracy of cyclic shift and timing offset estimation.

[0146] In some embodiments, as Figure 9 As shown, the cyclic shift estimation block 930 may include a detection block 932 and an estimation block 934 .

[0147] In some embodiments, the detection block 932 may detect a time index having a maximum value from the time domain samples of the channel impulse response calculated in the channel impulse response (CIR) calculation block 920 .

[0148] Some embodiments of the detection block 932 may be used with Figure 10 This corresponds to step 4 in .

[0149] As an example, the detection block 932 may find ix c The time index k with the maximum value in (n) max，c The time index kmax，c In the long-term evolution side link (LTE SL) and the new radio side link (NR SL), it can be expressed by Mathematical Formula 8 and Mathematical Formula 9 respectively.

[0150]

Mathematical formula 8

[0151]

[0152]

Mathematical formula 9

[0153]

[0154] In addition, in the long-term evolution side link (LTE S1), since the n cs The linear phase and ε can be expressed as And ε=(n cs / 3)·(N / 4) and n cs =0, 3, 6 or 9, when substituting it into the mathematical formula 8, (i.e. k in Long Term Evolution Sidelink (LTE SL) max，c ) can be organized into mathematical formula 10.

[0155]

Mathematical formula 10

[0156]

[0157] In some embodiments, the estimation block 934 may estimate cyclic shifts respectively corresponding to the at least one subchannel based on the time index detected in the detection block 932 .

[0158] Some embodiments of the detection block 932 may be used with Figure 10 This corresponds to step 5 in .

[0159] As an example, the estimation block 934 may estimate the cyclic shift based on the interval to which the time index having the maximum value of the channel impulse response belongs among the multiple intervals. In some embodiments, the multiple intervals may be intervals obtained by dividing the time domain interval of the channel impulse response based on statistical characteristics of the channel impulse response when the cyclic shifts corresponding to the M subchannels are given. As an example, the statistical characteristics of the channel impulse response may form a sinc function centered around each of the multiple intervals.

[0160] Figure 11 The channel impulse response (CIR) when there is no timing offset in the new air interface side link (LTE SL) is illustrated in FIG.

[0161] Specifically, Figure 11 The diagram shows When N=96, it is used to Determines the slice window of the cyclic shift of the Long Term Evolution Sidelink (LTE SL) and the channel impulse response (CIR) when the timing offset τ=0.

[0162] As an example, in In the case where the time index with the maximum value has a value greater than -4 but less than 4, the cyclic shift can be determined (ie, determined) to be n cs =0 (i.e. Figure 11 As shown, corresponding to cyclic shift index of the slice window to which it belongs).

[0163] After determining the cyclic shift, as described later, the timing offset can be estimated based on the determined cyclic shift.

[0164] The perception-based algorithm (SALG) technology is used to find Figure 11 The channel impulse response (CIR) value at the center of the slice window is shown by the black arrow in FIG, and the cyclic shift is estimated by comparing the channel impulse response (CIR) value. Figure 11 In the case where there is no timing offset, since the channel impulse response peak (CIRpeak) (i.e., the maximum value of the channel impulse response (CIR)) is detected, the cyclic shift estimation performance can be similar to that of some embodiments of the present disclosure. However, the estimation performance of the perception-based algorithm (SALG) technology is not as good as that of some embodiments of the present disclosure. Figure 12 The channel environment shown may be significantly degraded in the presence of timing offset, multipath and noise.

[0165] Figure 12 The channel impulse response (CIR) when there is a timing offset in the new air interface side link (LTE SL) is illustrated in FIG.

[0166] Specifically, Figure 12 and Figure 11 Different, the diagram shows the case with timing offset (timing offset ) slicing window and the channel impulse response (CIR). Figure 12 ,Because the channel impulse response (CIR) value at the center of the slice window does not have a maximum value due to timing offset, etc., the estimation performance of the perception-based algorithm (SALG) technology may be degraded.

[0167] In the new radio link (NR SL), since there is a demodulation reference signal resource element (DMRS RE) index k in every four resource elements (RE), the linear phase of i is And ε is By substituting the above values ​​into Equation 9, we can get (i.e. k in the New Radio Side Link (NR SL) max,c ) is organized into mathematical formula 11.

[0168]

Mathematical formula 11

[0169]

[0170] Figure 13 The channel impulse response (CIR) when there is no timing offset in the new radio side link (NR SL) is illustrated in FIG.

[0171] Specifically, Figure 13 The diagram shows When used from Determines the cyclic shift slicing window of the Long Term Evolution Sidelink (NR SL) and the channel impulse response (CIR) when the timing offset τ=0.

[0172] As an example, in In the case of (ie, the time index with the maximum value has a value greater than -20 and less than 20), the cyclic shift can be determined (ie, determined) to be i=0 (ie, Figure 13 As shown, corresponding to After determining the cyclic shift, as described later, the timing offset can be estimated based on the determined cyclic shift.

[0173] In addition, perception-based algorithm (SALG) technology such as Figure 11 In the description, find out Figure 13 The channel impulse response (CIR) value at the center of the slice window is shown by the black arrow in FIG, and the cyclic shift is estimated by comparing the channel impulse response (CIR) value. Figure 13 In the case where there is no timing offset, since the channel impulse response peak (CIR peak) (i.e., the maximum value of the channel impulse response (CIR)) is detected, the cyclic shift estimation performance can be similar to that of some embodiments of the present disclosure. However, the estimation performance of the perception-based algorithm (SALG) technology is not as good as that of some embodiments of the present disclosure. Figure 14 The channel environment shown may be significantly degraded in the presence of timing offset, multipath and noise.

[0174] Figure 14 The figure illustrates the channel impulse response (CIR) when there is a timing offset in the new radio side link (NR SL).

[0175] Specifically, Figure 14 and Figure 13 Different, the diagram shows the case with timing offset (timing offset ) slicing window and the channel impulse response (CIR). Figure 14 , because the channel impulse response (CIR) value at the center of the slice window does not have a maximum value due to timing offset, etc., the estimation performance of the perception-based algorithm (SALG) technology may be degraded. Furthermore, in the long-term evolution side link (LTE SL), the cyclic shift is ε = (n cs / 3)·(N / 4) and n cs =0, 3, 6 or 9, and the interval between the channel impulse response (CIR) peaks is (N / 4), but in the new air side link (NR SL), the cyclic shift is ε=i·(N / 12) and i=0, 1 or 2, and the interval between the channel impulse response (CIR) peaks is (N / 12). Therefore, in the new air side link (NR Sl), the timing offset may deviate from the peak main lobe. As a result, the probability of incorrectly estimating the cyclic shift will also increase.

[0176] In some embodiments, the timing offset estimation block 940 may estimate the timing offset based on the channel impulse response estimated in the cyclic shift estimation block 930 .

[0177] In some embodiments, the timing offset estimation block 940 may be configured to estimate the timing offset based on a ratio between a size (N) of a discrete Fourier transform (DFT) used when generating at least one set of received reference signals in the discrete Fourier transform (DFT) block 914 and a size (N) of an inverse discrete Fourier transform (IDFT) used when calculating a channel impulse response in the inverse discrete Fourier transform (IDFT) block 926, a time index (k) having a maximum value detected in the detection block 932, and a time index (k) having a maximum value detected in the detection block 932. max,c ) and the cyclic shift estimated in the estimation block 934 (e.g., n in the case of Long Term Evolution Sidelink (LTE SL) cs ; In the case of New Radio Side Link (NRSL), the timing offset is estimated based on i).

[0178] As an example, in Long Term Evolution Sidelink (LTE SL), the timing offset estimation block 940 may be Calculate the timing offset.

[0179] As another example, in the New Radio Side Link (NR SL), the timing offset estimation block 940 may be configured to estimate the timing offset of the NR SL by: Calculate the timing offset.

[0180] Figure 15 is a graph illustrating the performance of the disclosed cyclic shift estimation technique in Long Term Evolution Sidelink (LTE SL). Specifically, Figure 15The cyclic shift estimation performance of the disclosed technique and the perception-based algorithm (SALG) technique is illustrated in FIG.

[0181] As a simulation environment, the physical sidelink shared channel requirement test num. 4 (PSSCH requirement test num. 4) defined in the 3rd Generation Partnership Project (3GPP) standard document TS 36.101 Section 14.2 was used.

[0182] Figure 16 14.2-1 of the 3rd Generation Partnership Project standard document (3GPP 36.101) that specifies performance requirements related to timing offset and frequency offset in Long Term Evolution Sidelink (LTE SL) is shown in FIG.

[0183] Figure 17 FIG shows Table 14.2-2 of the 3rd Generation Partnership Project standard document (3GPP 36.101) which specifies the performance requirements for the Long Term Evolution Side Link (LTE SL).

[0184] As the simulation environment value, the frequency offset is set to 600Hz, and the timing offset is changed from 0 to 30T under the channel conditions of EVA2700. s The disclosed technique was compared with a perception-based algorithm (SALG) technique in terms of cyclic shift estimation performance. Furthermore, simulations were performed for a signal-to-noise ratio (SNR) value of 0.0 dB in addition to 2.8 dB defined in the standard document.

[0185] See Figure 15 It can be confirmed that both techniques can accurately estimate the cyclic shift when the timing offset is small. However, it can be confirmed that the timing offset CP / 2-12T clearly stated in the performance requirements s =24T s Under the guidance of the perception-based algorithm (SALG) technology, Figure 15 As shown, the accuracy at signal-to-noise ratio (SNR) = 0 dB and 2.8 dB has an estimation error of 0.941 and 0.983 respectively.

[0186] Figure 18 is a chart illustrating the performance of the disclosed cyclic shift estimation technique in Long Term Evolution Sidelink (NR SL). Specifically, Figure 18 The cyclic shift estimation performance of the disclosed technique and the perception-based algorithm (SALG) technique is illustrated in FIG.

[0187] As a simulation environment, the physical sidelink shared channel requirement test num. 4 defined in Section 11.13 of the 3rd Generation Partnership Project (3GPP) standard document TS 38.101-4 was used.

[0188] Figure 19 The performance requirements in the New Radio Side Link (NR SL) are illustrated in FIG (the minimum required performance described in Section 11.1.3 of TS 38.101-4).

[0189] As the simulation environment value, the frequency offset is set to 600Hz, and the timing offset is changed from 0 to 30T under the channel conditions of TDLA30-1400. s The disclosed technique was compared with a perception-based algorithm (SALG) technique in terms of cyclic shift estimation performance. Furthermore, simulations were performed for a signal-to-noise ratio (SNR) value of 0.0 dB in addition to 4.7 dB defined in the standard document.

[0190] See Figure 18 It can be confirmed that both techniques can accurately estimate the cyclic shift when the timing offset is small. However, it can be confirmed that the timing offset CP / 2-12T clearly stated in the performance requirements s =24T s Under the guidance of the perception-based algorithm (SALG) technology, Figure 18 As shown, the accuracies at SNR = 0 dB and 4.7 dB are 0.421 and 0.372 respectively, and the estimation error increases sharply.

[0191] In addition, as mentioned above, through Figure 18 It can be confirmed that in the perception-based algorithm (SALG) technology, the accuracy performance fluctuates with the timing offset due to exceeding the peak main lobe. Figure 18 It was confirmed that the lowest accuracy performance in the technology disclosed herein is 0.996, and accurate estimation can be maintained even when the timing offset is large.

[0192] The devices described above can be implemented by hardware components, software components, and / or a combination of hardware components and software components. For example, the devices and components described in the embodiments can be implemented using one or more general-purpose computers or special-purpose computers such as a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor (DSP), a microcomputer, a field programmable gate array (FPGA), a programmable logic unit (PLU), a microprocessor, or any other device that can execute instructions and respond. The processing device can execute an operating system (OS) and one or more software applications running on the operating system. In addition, the processing device can access, store, operate, process, and generate data in response to the software execution. For ease of understanding, in some cases, the use of a single processing device is used as an example, but a person with general knowledge in the relevant technical field should understand that the processing device can also include multiple processing elements and / or multiple types of processing elements. For example, the processing device can include multiple processors or a processor and a controller. In addition, other processing configurations such as parallel processors may also be used.

[0193] Software may include a computer program, code, instructions, or a combination of more than one of the foregoing, and may be configured to operate in a desired manner by configuring a processing device, or may be used to issue instructions to a processing device, either individually or collectively. Software and / or data may be embodied in some type of apparatus, component, physical device, computer storage medium, or device for parsing by a processing device or for providing instructions or data to a processing device. Software may be distributed across computer systems connected via a network so that it is stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable storage media.

[0194] According to the method of the embodiment, it can be implemented in the form of program instructions that can be executed by various computing devices and recorded in a computer-readable medium. At this time, the program that can be run by the calculation can be stored continuously, or temporarily stored for running or downloading. In addition, the medium can be a variety of recording devices or storage devices in the form of one or more hardware combinations, and is not limited to the medium directly connected to a certain computer system, and can also be dispersed on the network. As an example of the medium, it can include magnetic media such as hard disks and floppy disks and tapes, optical recording media such as read-only compact disks (CD-ROMs) and digital versatile disks (DVDs), magneto-optical media such as floptical disks (megneto-optical mediums), and read-only memories (ROMs), random access memories (RAMs), and flash memories, and program instructions can be stored. In addition, as an example of other media, it can include recording media to storage media managed in application stores for distributing applications or websites and servers for supplying or distributing various software.

[0195] As described above, the embodiments have been described with reference to a limited number of embodiments and drawings. However, persons having ordinary knowledge in the relevant technical fields can make various modifications and variations based on the description. For example, even if the described techniques are performed in a different order than the described method, and / or the described systems, structures, devices, circuits, and other components are combined or combined in a different manner than the described method, or are replaced or substituted with other components or equivalents, appropriate results can still be achieved.

[0196] Accordingly, other implementations, other embodiments, and equivalents thereof are within the scope of the appended claims.

Claims

1. A method of operating a receiver, An operating method for a receiver in a communication system in which at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol is transmitted as each reference signal set for first to Mth (M is a natural number greater than or equal to 2) subchannels via at least one of the at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol, the reference signal set including a plurality of reference signals cyclically shifted on the corresponding subchannel, is transmitted, comprising: generating at least one received reference signal set corresponding to the first subchannel based on a received signal, wherein the received reference signal set includes received reference signals received through corresponding orthogonal frequency division multiplexing (OFDM) symbols and the first subchannel; A step of calculating a channel impulse response of the first subchannel based on at least one received reference signal set corresponding to the generated first subchannel; as well as, The step of estimating a cyclic shift corresponding to the first subchannel based on the calculated channel impulse response of the first subchannel.

2. The operating method of the receiver according to claim 1, The step of generating at least one received reference signal set comprises: A step of extracting at least one set of samples corresponding to a symbol body of at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol from the received signal; Applying Discrete Fourier Transform (DFT) to the at least one sample set extracted, thereby generating at least one frequency domain signal; as well as, The step of extracting the received reference signals respectively included in at least one received reference signal set corresponding to the first subchannel from the generated at least one frequency domain signal.

3. The operating method of the receiver according to claim 1, The step of calculating the channel impulse response includes: generating time domain signals respectively corresponding to the at least one received reference signal set; as well as, The step of calculating the channel impulse response based on the generated at least one time domain signal.

4. The operating method of the receiver according to claim 3, The step of generating at least one time domain signal comprises: Applying descrambling to the at least one received reference signal set respectively, thereby generating at least one descrambling result symbol set; as well as, The step of applying an Inverse Discrete Fourier Transform (IDFT) to the generated at least one descrambling result symbol set, thereby generating the at least one time domain signal.

5. The operating method of the receiver according to claim 4, The size of the inverse discrete Fourier transform (IDFT) is four times the size of the inverse discrete Fourier transform (IDFT) object, ie, the descrambled result symbol set.

6. The operating method of the receiver according to claim 4, The size of the inverse discrete Fourier transform (IDFT) is greater than or equal to the size of the inverse discrete Fourier transform (IDFT) object, that is, the size of the descrambling result symbol set. The step of applying the inverse discrete Fourier transform (IDFT) includes: The step of configuring the center of the inverse discrete Fourier transform (IDFT) object, that is, the descrambled result symbol set, to the center position of the inverse discrete Fourier transform (IDFT) window and applying the inverse discrete Fourier transform (IDFT).

7. The operating method of the receiver according to claim 3, The reference signal set of the first subchannel is transmitted via an Orthogonal Frequency Division Multiplexing (OFDM) symbol, The step of generating at least one received reference signal set comprises: generating a receive reference signal set corresponding to the first subchannel; The step of generating at least one time domain signal comprises: generating a time domain signal corresponding to the generated one received reference signal set; The step of calculating the channel impulse response includes the step of determining the generated time domain signal as the channel impulse response.

8. The operating method of the receiver according to claim 3, The reference signal set of the first subchannel is transmitted through multiple orthogonal frequency division multiplexing (OFDM) symbols, The step of generating at least one received reference signal set comprises: generating a plurality of receive reference signal sets corresponding to the first subchannel; The step of generating at least one time domain signal comprises: generating time domain signals respectively corresponding to the generated multiple received reference signal sets; The step of calculating the channel impulse response includes the step of summing the time domain samples respectively contained in the generated multiple time domain signals according to the same time index, thereby calculating the channel impulse response.

9. The operating method of the receiver according to claim 1, The step of estimating the cyclic shift comprises: A step of detecting a time index having a maximum value among the time domain samples of the channel impulse response; as well as, The step of estimating a cyclic shift corresponding to each of the at least one subchannel based on the detected time index.

10. The operating method of the receiver according to claim 9, The step of estimating the cyclic shift comprises: A step of estimating the cyclic shift based on an interval to which a time index having a maximum value of the channel impulse response belongs among a plurality of intervals; The multiple intervals are obtained by dividing the time domain interval of the channel impulse response based on the statistical characteristics of the channel impulse response when the cyclic shifts corresponding to the M sub-channels are given.

11. The operating method of the receiver according to claim 10, The statistical characteristics of the channel impulse response form sinc functions with the multiple intervals as centers.

12. The operating method of the receiver according to claim 1, further comprising: The step of estimating a timing offset based on the estimated channel impulse response.

13. The operating method of the receiver according to claim 12, The step of estimating the cyclic shift comprises: A step of estimating cyclic shifts respectively corresponding to the at least one subchannel based on a time index having a maximum value in the time domain samples of the channel impulse response; The step of estimating the timing offset includes: estimating the timing offset based on the ratio between the size of the discrete Fourier transform (DFT) used when generating the at least one received reference signal set and the size of the inverse discrete Fourier transform (IDFT) used when calculating the channel impulse response, the time index with the maximum value, and the estimated cyclic shift.

14. The operating method of the receiver according to claim 1, further comprising: For each m (the value of m is 2 to M), generating, based on the received signal, at least one received reference signal set corresponding to the m-th subchannel, wherein the received reference signal set includes received reference signals received through corresponding orthogonal frequency division multiplexing (OFDM) symbols and the m-th subchannel; The step of calculating a channel impulse response of the mth subchannel based on at least one received reference signal set corresponding to the generated mth subchannel; as well as, The step of estimating a cyclic shift corresponding to the mth subchannel based on the calculated channel impulse response of the mth subchannel.

15. The operating method of the receiver according to claim 1, The first to M-th sub-channels respectively include a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) of a long term evolution (LTE) sidelink, The reference signal sets of the first to Mth subchannels respectively include reference signal sets of a physical sidelink control channel (PSCCH) included in the corresponding subchannel.

16. The operating method of the receiver according to claim 1, The first to M-th sub-channels respectively include a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) of the new radio (NR) side link, The reference signal sets of the first to Mth subchannels respectively include reference signal sets of a physical sidelink control channel (PSCCH) included in the corresponding subchannel.

17. A receiving device, A receiving apparatus in a communication system for transmitting at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol - each reference signal set of first to Mth (M is a natural number greater than or equal to 2) subchannels via at least one of the at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol, wherein the reference signal set includes a plurality of reference signals with cyclic shifts applied on corresponding subchannels, including: a received reference signal set generation block, configured to generate at least one received reference signal set corresponding to the first subchannel based on a received signal, wherein the received reference signal set includes received reference signals received through corresponding orthogonal frequency division multiplexing (OFDM) symbols and the first subchannel; a channel impulse response calculation block, calculating a channel impulse response of the first subchannel based on at least one received reference signal set corresponding to the generated first subchannel; as well as, The cyclic shift estimation block estimates the cyclic shift corresponding to the first subchannel based on the calculated channel impulse response of the first subchannel.

18. The receiving device according to claim 17, The received reference signal set generation block includes: a sample set extraction block, extracting at least one sample set respectively corresponding to a symbol body of the at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol from the received signal; a discrete Fourier transform (DFT) block for applying a discrete Fourier transform (DFT) to each of the at least one sample set extracted, thereby generating at least one frequency domain signal; and The received reference signal extraction block extracts the received reference signals respectively included in at least one received reference signal set corresponding to the first subchannel from the generated at least one frequency domain signal.

19. The receiving device according to claim 17, The channel impulse response calculation block includes: A time domain signal generation block generates time domain signals respectively corresponding to the at least one received reference signal set; as well as, A calculation block calculates the channel impulse response based on the generated at least one time domain signal.

20. The receiving device according to claim 19, The time domain signal generation block includes: a descrambling block, applying descrambling to the at least one received reference signal set respectively, thereby generating at least one descrambling result symbol set; as well as, An inverse discrete Fourier transform (IDFT) block applies an inverse discrete Fourier transform (IDFT) to the generated at least one descrambling result symbol set, thereby generating the at least one time domain signal.

21. The receiving device according to claim 17, The cyclic shift estimation block comprises: a detection block, detecting a time index having a maximum value among the time domain samples of the channel impulse response; as well as, The estimation block estimates the cyclic shift corresponding to the at least one subchannel based on the detected time index.

22. The receiving device according to claim 17, further comprising: The timing offset estimation block estimates the timing offset based on the estimated channel impulse response.

23. The receiving device according to claim 17, For each m (the value of m is 2 to M), The received reference signal set generation block generates at least one received reference signal set corresponding to the m-th subchannel based on the received signal, wherein the received reference signal set includes received reference signals received through corresponding orthogonal frequency division multiplexing (OFDM) symbols and the m-th subchannel, respectively. The channel impulse response calculation block calculates the channel impulse response of the mth subchannel based on the at least one received reference signal set corresponding to the generated mth subchannel, The cyclic shift estimation block estimates the cyclic shift corresponding to the mth subchannel based on the calculated channel impulse response of the mth subchannel.

24. The receiving device according to claim 17, The first to M-th sub-channels respectively include a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) of a long term evolution (LTE) sidelink, The reference signal sets of the first to Mth subchannels respectively include reference signal sets of a physical sidelink control channel (PSCCH) included in the corresponding subchannel.

25. The receiving device according to claim 17, The first to M-th sub-channels respectively include a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) of the new radio (NR) side link, The reference signal sets of the first to Mth subchannels respectively include reference signal sets of a physical sidelink control channel (PSCCH) included in the corresponding subchannel.

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