Method and apparatus for receiving control channel

Abstract

A method for receiving a control channel in a sidelink is presented. The method may comprise the steps of: using a first index from among a plurality of candidate orthogonal indexes so as to generate a reference signal for a control channel; performing a differential correlation calculation for the correlation between the reference signal for the received candidate control channel and the generated reference signal; applying phase rotation or phase correction to the result of the differential correlation calculation so as to detect a minimum phase value and an orthogonal index corresponding to the minimum phase value; and using the minimum phase value and a normalized power value acquired on the basis of the differential correlation calculation, so as to determine whether presence detection of a control channel is successful or the orthogonal index used for the control channel.

Description

Control channel receiving method and device

[0001] The present invention relates to wireless communication technology, and more particularly, to a method and device for receiving a control channel.

[0002] Sidelink refers to a communication method that establishes a direct link between terminals, allowing voice or data to be exchanged directly between them without going through a base station. Sidelink is being considered as a solution to address the burden on base stations caused by rapidly increasing data traffic.

[0003] V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-based objects through wired / wireless communication. V2X can include V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian).

[0004] 5G communication standards utilize a sidelink transmission method for V2X, which also has separate control and data channels. However, unlike downlink transmission and reception between terminals and base stations, sidelinks are defined so that the other party (terminal) cannot know the index used to generate the sequence code. Only candidate values ​​are provided, and the selection is determined by the transmitter.

[0005] Additionally, since side links are performed in an environment where both the sender and receiver are moving, timing errors may occur, and the receiver must take this into account.

[0006] Accordingly, the present invention proposes a method or device for receiving a control channel in a side link.

[0007] The problems to be solved by the present invention are not limited to the problems to be solved above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0008] A method for receiving a control channel in a side link is proposed, the method comprising: generating a reference signal for the control channel using a first index among a plurality of candidate orthogonal indices; performing a differential correlation operation on a correlation between the reference signal for the received candidate control channel and the generated reference signal; applying a phase rotation or phase correction to a result of the differential correlation operation to detect a minimum phase value and an orthogonal index corresponding to the minimum phase value; and determining whether detection of the presence of the control channel is successful or an orthogonal index used for the control channel using the minimum phase value and a normalized power value obtained based on the differential correlation operation.

[0009] In a side link communication, a device for receiving a control channel is proposed, the device including: a signal generator for generating a reference signal for a control channel using a first index among a plurality of candidate orthogonal indices; a differential correlator for performing a differential correlation operation on a correlation between a reference signal for a received candidate control channel and the generated reference signal; a phase rotation and correction unit for applying a phase rotation or a phase correction to a result of the differential correlation operation to detect a minimum phase value and an orthogonal index corresponding to the minimum phase value; and a discriminator for determining whether the presence of a control channel is successfully detected or an orthogonal index used for the control channel using the minimum phase value and a normalized power value obtained based on the differential correlation operation.

[0010] The above problem solving methods are only some of the embodiments of the present invention, and various embodiments reflecting the technical features of the present invention can be derived and understood by a person having ordinary knowledge in the relevant technical field based on the detailed description of the present invention described below.

[0011] The present invention has the following effects.

[0012] The performance of detecting reception of a side link control channel in a receiving device can be improved.

[0013] The reception of a side link control channel can be detected by reflecting timing errors that may occur in the side link at the receiving device.

[0014] The accompanying drawings, which are included as part of the detailed description to aid in understanding the present invention, provide embodiments of the present invention and, together with the detailed description, explain the technical idea of ​​the present invention.

[0015] Figure 1 illustrates a V2X communication environment.

[0016] Figure 2 illustrates resource allocation of NR V2X.

[0017] Figure 3 illustrates the structure of the control channel and data channel of NR V2X.

[0018] Figure 4 illustrates a procedure for PSCCH DMRS detection.

[0019] Figure 5 shows the detailed structure of the correlator and differential correlator.

[0020] Figure 6 shows the detailed structure of the phase rotation and compensator.

[0021] Figures 7 to 9 are simulation results showing phase values ​​according to timing error (offset).

[0022] Figure 10 shows a block diagram of a transmitter and a receiver.

[0023] Figure 11 illustrates a block diagram of a processor of a receiving device.

[0024] Figure 12 illustrates a flowchart of a control channel receiving method.

[0025] Figures 13 to 16 show simulation results related to control channel reception.

[0026] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be implemented in various other forms. The terminology used herein is intended to aid understanding of the embodiments and is not intended to limit the scope of the present invention. Furthermore, the singular forms used below also include the plural forms, unless the context clearly indicates otherwise.

[0027] Figure 1 illustrates a communication environment to which the present invention is applied.

[0028] V2X (Vehicle to Everything) refers to a communication system that includes wireless communication (V2V) between vehicles (2). V2V not only plays a fundamental role of informing surrounding vehicles of information such as the vehicle's location, direction, and speed, but also serves to notify potential hazards such as sudden braking and directional changes.

[0029] In addition, V2X refers to a system in which automobiles communicate and share with various elements on the road for autonomous driving, such as wireless communication between vehicles and networks (3) (V2N), wireless communication between vehicles and road side units (RSU) (4), and wireless communication between vehicles and traffic infrastructure (5) (V2I).

[0030] It can be used to inform each other of dangers through vehicle-to-vehicle communication, or to check information such as parking lot locations and signal change times through vehicle-to-vehicle communication with traffic infrastructure such as parking lots and traffic lights. It is considered an essential technology for perfect autonomous driving.

[0031] V2X is implemented through sidelink within the 5G communication standard. Vehicles, i.e., the transmitter and receiver, transmit and receive information through sidelink.

[0032]

[0033] Figure 2 illustrates resource allocation of NR sidelink (SL).

[0034] In NR V2X, only certain slots are (pre-)configured to contain SL transmission. Therefore, the available SL resources consist of slots (time resources) allocated for SL and common resource blocks (RBs) (frequency resources) within the SL bandwidth part (BWP). In NR V2X, a subset of the available SL resources is (pre-)configured to be used by several UEs for their SL transmission. This subset of available SL resources is called a resource pool and is illustrated in Figure 2. The common RBs within the resource pool are called physical resource blocks (PRBs). A resource pool consists of contiguous PRBs (pre-)configured for SL transmission and contiguous or non-contiguous slots. A resource pool must be defined within the SL BWP.

[0035] In the frequency domain, the resource pool is divided into a (pre-)configured numSubchannels of contiguous sub-channels, where a sub-channel consists of a group of contiguous PRBs in a slot. The subchannelSize PRBs within a sub-channel correspond to the sub-channel size, which is (pre-)configured within the resource pool. In NR V2X SL, the sub-channel size (subchannelSize) can be 10, 12, 15, 20, 25, 50, 75 or 100 PRBs. A sub-channel represents the smallest unit for SL data transmission or reception. An SL transmission can use one or more sub-channels.

[0036] In the time domain, slots, which are part of a resource pool, are (pre-)set and occur at a period of 10240ms. Slots, which are part of a resource pool, can be (pre-)set as a bitmap, and the length of the bitmap can be 10, 11, 12, ..., 160.

[0037]

[0038] Figure 3 illustrates the structure of the control channel and data channel of NR SL.

[0039] In NR SL, PSCCH (Physical Sidelink Control Channel) is used to transmit control information between terminals, and PSSCH (Physical Sidelink Shared Channel) is used to transmit data.

[0040] PSCCH and PSSCH are multiplexed and transmitted as a pair within a single slot, and can be transmitted using one or more sub-channels. That is, when a BWP consists of multiple sub-channels, each sub-channel corresponds to a candidate sub-channel on which the PSCCH and PSSCH can be transmitted.

[0041] The PSCCH is used to transmit 1st-stage Sidelink Control Information (SCI), which is required for decoding the PSSCH, which is multiplexed in pairs. Therefore, for smooth PSSCH decoding, the PSCCH must first be successfully decoded. Three demodulation reference signals (DMRS) are transmitted per RB on the PSCCH, and the receiver must perform demodulation using the received DMRS.

[0042] For PSCCH DMRS and the generation of DMRS sequences, refer to the relevant section of 3GPP TS 38.211, V17.1.0, as follows.

[0043]

[0044] As explained above, three PSCCH DMRSs are generated within 1RB and allocated and transmitted to resources (k'=0, 1, 2), and w according to the orthogonal index i in units of 1RB. f,i This sequence is multiplied. At this time, since the orthogonal index i is set to be randomly selected by the transmitter, the receiver cannot know the orthogonal index i of the received PSCCH DMRS. Therefore, the receiver must determine the presence or absence of a PSCCH in each sub-channel for each reception slot and detect the orthogonal index used in the transmitted PSCCH DMRS. Conventionally, detection was attempted by performing blind decoding on three orthogonal indices in each sub-channel.

[0045] In addition, since the V2X communication method involves communication between terminals (vehicles or RSUs (road side units)), a certain level of timing error may occur, and the receiving side must be able to robustly detect the presence or absence of PSCCH DMRS (or PSCCH) and the orthogonal index even if a certain level of timing error occurs.

[0046]

[0047] Figure 4 illustrates a procedure for detecting a control channel (or control channel DMRS). The procedure is performed on the receiving side of the control channel (or control channel DMRS).

[0048] Own DMRS & w f,i Generation (11) is a signal generation method that is promised in advance, for example, PSCCH DMRS defined in a standard document is generated based on relevant parameters, and w for a specific candidate orthogonal index (i) f,i It is about the creation of .

[0049] Differential correlation and phase rotation, correction (12) is performed by the candidate control channel DMRS received from the transmitter side and the control channel DMRS generated at the receiver side and w f,iIt relates to calculating correlation using and obtaining differential correlation, and applying phase rotation and correction to the result. Here, the control channel DMRS received from the transmitting side is referred to as a "candidate" because it is not known whether the received DMRS is a control channel DMRS for the receiving side until the detection determination (13) is completed.

[0050] Detection determination (13) compares the phase rotation and corrected values ​​with the reference value (threshold value) to determine whether a control channel (or control channel DMRS) exists, and if a control channel exists, w f,i (or orthogonal index i) is about determining.

[0051] Hereinafter, details for detecting a control channel (or control channel DMRS) and detecting an orthogonal index of the control channel are described with reference to FIGS. 5 and 6.

[0052] Figure 5 illustrates a detailed functional block diagram of differential correlation associated with the control channel DMRS.

[0053] Referring to FIG. 5, the differential correlation is composed of a received control channel DMRS, a generated control channel DMRS correlator (121), and a DMRS differential correlator (122). As illustrated in FIG. 6, the differential correlation value (diffCorr), which is the output of the DMRS differential correlator (122), is input to a phase rotation and correction unit (123).

[0054] The correlator (121) receives the control channel DMRS ( ) and the control channel DMRS using the candidate orthogonal index i=0 generated on the receiving side. ) is used to compute the correlation. For this purpose, the receiver calculates the control channel DMRS ( for the candidate orthogonal index i = 0. ) needs to be created, as follows:

[0055] For candidate orthogonal index i=0, for each candidate receiving antenna port (p), the control channel (PSCCH) DMRS can be generated as follows. Here, l is the OFDM symbol index to which the control channel DMRS in the slot is mapped, and j is the RB index for the control channel. is the symbol index where the sidelink sub-channel starts, is the number of symbols allocated for PSCCH, is the starting RB index of the sidelink sub-channel, represents the number of RBs allocated for the control channel, and k' represents a constant having an integer value from 0 to 2 to indicate the frequency resource (subcarrier) index to which the control channel DMRS is mapped.

[0056]

[0057] In mathematical expression 2, w f,O(k') (w when i=0 f,i Since value) = 1, we can see that it has been replaced with 1.

[0058] Also, referring to Equation 2, For each OFDM symbol (l) to which the control channel DMRS can be mapped, You can see that the dog has been created.

[0059] c'(n) is the control channel DMRS sequence r referenced above. l (m) is defined based on, , and c(n) corresponds to a pseudo-random sequence specified in 3GPP TS38.211. w f,i Refer to the contents of 3GPP TS38.211 referenced above.

[0060] Receive Control Channel DMRS( ) and the 0th orthogonal index generated on the receiving side. The operation of the correlation is class It can be expressed as the product of the complex conjugates of . In detail, as follows: can be expressed as

[0061]

[0062] p is the antenna port index, l, j, k' are the indices described above. represents the control channel DMRS received at antenna port index = p, OFDM symbol index = l, and subcarrier index = q, represents the number of receiving antenna ports, and * represents the conjugate complex operator.

[0063] Referring to mathematical expression 3, For each OFDM symbol (l) to which the reception control channel DMRS can be mapped, You can see that the dog has been created.

[0064] The result of the correlator (121) operation ( ) is input to the differential correlator (122), which is It is used to obtain the first value (diffCorr) which is the accumulated result of the differential correlation and the second value (normPower) which is the normalized power value. The second value (normPower) is the result of dividing the power value of the accumulated value of the differential correlation by the accumulated value of the power value of each differential correlation value multiplied by a constant.

[0065] Using , diffCorr, diffEnergy, and normPower can be obtained by calculating them as follows.

[0066]

[0067] As explained earlier, is for each OFDM symbol (l). The dog is obtained, and since mathematical expression 4 is an operation between these, the number of operations possible is as many as the number of cases that are 1 less than that, so m is set as above, -1 operation is performed.

[0068] The first value (diffCorr) corresponds to the result of the differential correlation operation for the candidate orthogonal index i=0, and looking at the operation of the first value (diffCorr), in the consecutive resource locations (subcarriers) is the autocorrelation operation and its cumulative sum. If the phase (angle) of the result of this operation is close to 0, the control channel DMRS ( generated from the corresponding orthogonal index, receiving antenna port, and resource location) ) is the received signal ( ) is likely to be the same.

[0069] In mathematical expression 14 described below, the phase (angle) range for determining the identity of two signals is set to a range within π / 3 in absolute value, and the value of this range is only an example. The receiving side performs the identity determination of these two signals for all candidate orthogonal indices, receiving antenna ports, time resources (i.e., OFDM symbols), and frequency resources (i.e., subcarriers). However, in the case of candidate orthogonal indices, the control channel DMRS is not generated for all candidate orthogonal indices, but rather, as described below, a preset phase difference between the candidate orthogonal indices is used.

[0070] Once the first value (diffCorr) is obtained, a set of phase values ​​of differential correlation values ​​for multiple candidate orthogonal indices using the first value is obtained as follows. As explained above, the receiver only generated a control channel DMRS for a specific candidate orthogonal index (i=0) and performed correlation operations with the reception control channel DMRS, and did not perform separate operations for the remaining candidate orthogonal indices (i=1, 2). Through the following process, the phase values ​​of the differential correlations for the remaining candidate orthogonal indices can be obtained without generating control channel DMRSs for the remaining candidate orthogonal indices.

[0071] 1) First step (obtaining the phase value of the differential correlation for all candidate orthogonal indices)

[0072] Referring to mathematical expression 1, the orthogonal index i=0 has a phase difference of 2 / 3 π with the orthogonal index i=1, and the orthogonal index i=2 has a phase difference of -2 / 3 π.

[0073] Therefore, the differential correlation value of orthogonal index i=1 will have a phase difference of 2 / 3 π from the differential correlation value of orthogonal index i=0, and the differential correlation value of orthogonal index i=2 will have a phase difference of -2 / 3 π from the differential correlation value of orthogonal index i=0.

[0074] Therefore, as shown in Fig. 6, θ0, θ1, and θ2 can be obtained as follows. θ0 is the phase value of the differential correlation between the received control channel DMRS and the control channel for the candidate orthogonal index i=0, θ1 is the phase value of the differential correlation between the received control channel DMRS and the control channel for the candidate orthogonal index i=1, and θ2 is It means the phase value of the differential correlation between the received control channel DMRS and the control channel for candidate orthogonal index i=0.

[0075]

[0076]

[0077]

[0078] That is, the result of the differential correlation operation for candidate orthogonal index i=1 is , and the result of the differential correlation operation for candidate orthogonal index i=2 is can be expressed as . Here, the phase rotation value (θ pr,1 , θ pr,2 ) can be 2 / 3π and -2 / 3π, respectively.

[0079] As expressed in Equations 6 and 7, the present proposal does not generate control channel DMRSs for all candidate orthogonal indices and compares them with the received control channel DMRSs (correlation operation and differential correlation of correlation values), but generates only a control channel DMRS for candidate orthogonal index i=0 and compares it with the received control channel DMRSs to obtain the phase value of the differential correlation, and for the remaining candidate orthogonal indices i=1 and 2, a phase rotation value is applied to the differential correlation for candidate orthogonal index i=0 to obtain the phase value of the differential correlation.

[0080]

[0081] 2) Second step (obtaining phase values ​​of differential correlation reflecting timing errors for all candidate orthogonal indices)

[0082] As previously explained, sidelink communication environments are expected to frequently involve transmission and reception while the transmitter and receiver are moving, requiring robustness against timing errors. Phase compensation is necessary to account for timing errors.

[0083] When timing errors exist, the linear phase difference between two consecutive subcarriers can be defined as follows:

[0084]

[0085] Here, if FFT_SIZE is 1024 and the subcarrier spacing is 30 kHz, the length of a normal cyclic prefix (CP) corresponds to 72 samples. In this case, if only the timing error within the CP range is considered, a timing error of at least 0 samples to 72 samples can occur, and the sidelink control channel (PSCCH) DMRS is arranged at a subcarrier spacing of 4 (see Equation 1).

[0086] If a timing error of up to 72 samples occurs, the maximum linear phase difference that can occur between two consecutive DMRSs is:

[0087]

[0088] Therefore, assuming an ideal channel situation, a phase correction corresponding to -9π / 16, which corresponds to the maximum linear phase difference value, can be applied to the differential correlation value so that the phase value of the differential correlation value becomes 0 when a timing error of up to 72 samples occurs.

[0089] Accordingly, the phase values ​​reflecting phase correction considering timing error in θ0, θ1, and θ2 are as follows.

[0090]

[0091]

[0092]

[0093] That is, the phase correction result of the differential correlation for candidate orthogonal index i=0 is , and the phase correction result of the differential correlation for candidate orthogonal index i=1 is , and the phase correction result of the differential correlation for candidate orthogonal index i=2 is can be expressed as . Here, the phase correction value (θ pc ) can be -9 / 16π.

[0094] The results of calculating the phase value according to Equations 5 to 7 and Equations 10 to 12 are obtained through simulation according to the timing error (timing offset) and are shown in Figures 7 to 9.

[0095] The simulations related to FIGS. 7 to 9 are for the case where control channel DMRS having orthogonal indices (OCC indexes) of 0, 1, and 2 are received (transmitted), respectively.

[0096] In each of FIGS. 7 to 9, six phase values ​​according to timing offset are shown, and each corresponds to θ0 (OCC index 0), θ1 (OCC index 1), θ2 (OCC index 2), θpc,0 (OCC index 0 with PC), θpc,1 (OCC index 1 with PC), and θpc,2 (OCC index 2 with PC).

[0097] In FIGS. 7 to 9, it can be confirmed that, at each timing offset value, the orthogonal index corresponding to the phase value having the minimum value corresponds to the orthogonal index used in the control channel DMRS (indices 0, 1, and 2, respectively).

[0098] This is in line with the expectation that the phase of the differential correlation value will be close to 0 if the DMRSs are identical, based on the identity judgment between the received candidate control channel DMRS and the control channel DMRS generated by the receiver, as explained above.

[0099] Again, going back to Equation 4, if we look at the calculation of the second value (normPower), diffEnergy (differential power) is the difference in power at consecutive resource locations (subcarriers). The square value (power value) of the differential correlation result and its cumulative sum. The second value (normPower) is the square of the first value multiplied by diffEnergy and the number of differential correlation operations (or dot dot( It corresponds to the result of dividing by the product of -1).

[0100]

[0101] As the output of the phase rotation compensator (123) shown in Fig. 6, θ0, θ1, θ2, θpc,0, θpc,1, θpc,2 are obtained, and these are used as inputs of the detection discriminator (13).

[0102] The detection discriminator (13) determines whether the received candidate control channel DMRS is a control channel DMRS generated with a certain orthogonal index. At this time, not only the first value (diffCorr) based on the differential correlation but also the second value (normPower) is used. The second value is intended to consider the power of the received candidate control channel DMRS. Consequently, the detection discriminator (13) considers not only the phase value of the differential correlation value but also the power value.

[0103] 1) First step - detection of orthogonal indices with minimum phase value

[0104]

[0105] The first step is to determine the minimum phase value (minAbsPhase) and its corresponding orthogonal index. As explained with reference to FIGS. 6 and 7 to 9, the smallest value among the obtained θ0, θ1, θ2, θpc,0, θpc,1, and θpc,2 is selected, and the orthogonal index of that value is determined. This process is expressed in Equation 13.

[0106] 2) Second step - Comparison of minimum phase value and phase reference value, and comparison of power value and power reference value.

[0107] The minimum phase value does not necessarily indicate successful detection of the control channel or control channel DMRS. To this end, the receiver can compare the previously acquired second value (normPower) with the power reference value, and compare the minimum phase value with the phase reference value.

[0108] If the second value (normPower) is greater than the power reference value and the minimum phase value is less than the phase reference value, the receiving side succeeds in detecting the control channel or control channel DMRS, and the orthogonal index at that time corresponds to detOCCIndex (0, 1, or 2).

[0109] Otherwise, the receiving side is deemed to have failed to detect the control channel or control channel DMRS.

[0110] Here, the power reference value (Thpower) and phase reference value (2 / 3π) can also be expressed in other terms and correspond to values ​​that can be set in the transmitting / receiving system or the receiving side. This process is expressed in mathematical equation 14.

[0111]

[0112] Meanwhile, the detection and determination method according to mathematical formula 13 is tan as shown in mathematical formulas 5 to 7 and 10 to 12 at each phase value. -1 There is a concern that the implementation may increase the processing load due to the use of operations.

[0113] Therefore, tan -1 The following method, which does not use operations, is applicable.

[0114]

[0115] The procedure according to mathematical formula 15 is first performed, using the first value (diffCorr) obtained above. The first value is the value obtained for the orthogonal index 0. When the first value is located in the 1st and 4th quadrants among the 4 quadrants, the real part of the first value at that time is set to the real part of phaseTmp, and the imaginary part of the first value is set to the imaginary part of phaseTmp by taking the absolute value. When the first value is located in the 2nd and 3rd quadrants, the real part of phaseTmp is set to 0, and the imaginary part is set to the maximum value. Then, the orthogonal index (detOCCIndex) corresponding to the minimum phase is set to 0, which is a temporary value.

[0116] The condition of Equation 15 is whether the first value is in the 1st and 4th quadrants. Since this process is to determine the minimum phase value of the differential correlation value for each orthogonal index, if the phase of the differential correlation value for the orthogonal index 0 is not in the 1st and 4th quadrants (since it is eventually confirmed that it is less than the reference phase value 1 / 3π as mentioned in Equation 14) (i.e., because the absolute value of the phase value of the first value is greater than 1 / 2π), it is not treated as a candidate for the minimum phase value.

[0117]

[0118] Index (k-1)phaseVal[k-1] (phase correction (or rotation) value)0 1 2 3 4

[0119] Next, the procedure according to mathematical formula 16 is performed.

[0120] For the values ​​of k(1, 2, 3, 4, 5), this is a process of comparing the phaseTmp determined in Equation 15 with the result of applying the phase correction (or rotation) values ​​shown in Table 1 to the first value (diffCorr) to find out whether there is a smaller phase value. The phase correction (or rotation) values ​​shown in Table 1 are identical to the values ​​expressed in Equations 6 to 7 and Equations 10 to 12.

[0121] That is, when the condition in mathematical expression 16 is met, the index corresponding to the minimum phase is newly set, and this is when the value (tmp) obtained by phase-correcting the first value (diffCorr) is a value located in the 1st or 4th quadrant, and the size of the imaginary part of tmp is smaller than the size of the imaginary part of phaseTmp determined in mathematical expression 15. That is, the size of the differential correlation value is 1 because the size of the pseudo-random sequence on which it is based is 1. Therefore, the phase size comparison is possible by comparing the sizes of the real part or the imaginary part. In mathematical expression 16, the sizes of the imaginary parts of tmp and phaseTmp are compared in the conditional statement, but it can also be modified to determine whether it is larger than phaseTmp by comparing the sizes of the real parts.

[0122] If there is a value whose phase is smaller than the reference value (phaseTmp) based on the first value (diffCorr), the receiving side sets the real and imaginary parts of the corresponding value to the real and imaginary parts of phaseTmp, respectively, and can determine the orthogonal index (detOCCIndex) corresponding to the minimum phase based on the k value at that time.

[0123] Then, the receiving side can calculate the minimum phase value (minAbsPhase) based on the real and imaginary parts of the determined phaseTmp as follows.

[0124]

[0125] Thereafter, the receiving side can determine whether the detection of the presence of the control channel is successful and the detected orthogonal index in case of success by comparing the minimum phase value and the phase reference value and the normalized power value and the power reference value, as expressed in Equation 14.

[0126]

[0127] Figure 10 shows a block diagram of a transmitter and a receiver.

[0128] The transmitting device (20) refers to a device on the transmitting side that transmits messages, data, etc. for V2X communication. However, since communication always involves transmission and reception, the transmitting device (20) can also receive messages, data, etc.

[0129] The transmitting device (20) may include a memory (21) for storing messages, data, information, etc., a processor (22) for processing messages, data, information, etc., and a transceiver (23) for transmitting or receiving messages, data, information, etc.

[0130] The receiving device (30) refers to a receiving device that receives messages, data, etc. for V2X communication. The receiving device (20) can also transmit messages and data.

[0131] The receiving device (30) may include a memory (31) for storing messages, data, information, etc., a processor (32) for processing messages, data, information, etc., and a transceiver (33) for transmitting or receiving messages, data, information, etc.

[0132] The transmitter (20) and receiver (30) can each be mounted on equipment or devices for V2X communication, such as a vehicle or RSU (road side unit).

[0133] A transmitting device (20) can transmit a sidelink channel to a receiving device (30) via a sidelink, and the receiving device (30) can detect the sidelink channel and obtain necessary information. As previously explained, the sidelink also consists of a control channel indicating a data channel and a data channel, and reception of the control channel is required to receive the data channel.

[0134] However, in the sidelink, rather than using the promised orthogonal index (i) between the transmitting device (20) and the receiving device (30), it is designed so that the transmitting device (20) randomly determines one of the preset parameter sets (i.e., multiple orthogonal index i candidates). Accordingly, the receiving device (30) needs to receive an efficient sidelink control channel rather than attempting to decode all parameter sets. In addition, since timing errors will occur due to the characteristics of V2X communication, a control channel reception method that takes this into consideration is required.

[0135] For this purpose, the content of the technology described with reference to FIGS. 4 to 6 described above can be performed in the receiving device (30). According to this technology, detection of the control channel and determination of the used orthogonal index can be performed without attempting to decode all signals received in the candidate resource area.

[0136]

[0137] Fig. 11 illustrates a block diagram of a processor (32) of a receiving device (30). The receiving device (30) performs operations related to control channel DMRS detection described with reference to Figs. 4 to 6 in sidelink communication. That is, the processor (32) is a device configured to receive a control channel DMRS.

[0138] The processor (32) may include a signal generator (321), a differential correlator (322), a phase rotator and compensator (323), and a discriminator (324).

[0139] The signal generator (321) can generate a control channel demodulation reference signal (DMRS) for each candidate orthogonal index. The generation of the control channel DMRS is performed based on the mathematical expression 2 described above and the description related thereto.

[0140] The differential correlator (322) can perform a correlation operation between the candidate control channel DMRS received from the transmitter (20) through the transceiver (33) and the DMRS generated from the signal generator (321). The differential correlator (322) can perform a correlation operation on the result of the correlation operation ( ) can perform a differential correlation operation. Then, the differential correlator (322) can accumulate the results of the differential correlation to obtain a first value (diffCorr).

[0141] In addition, the differential correlator (322) can calculate the square value (power value) of the result of the differential correlation and accumulate it to calculate the accumulated power value (diffEnergy). The differential correlator (322) can calculate the second value (normPower) by squaring the first value and dividing the calculated accumulated power value by a value obtained by multiplying a constant.

[0142] The phase rotation and compensation unit (323) can apply phase rotation or phase compensation to the acquired first value (diffCorr), as shown in Fig. 6, and using mathematical expressions 5 to 7 and mathematical expressions 10 to 12. The phase rotation value (θ pr,1 , θ pr,2 ) can be 2 / 3π and -2 / 3π, respectively. In addition, the phase correction value (θ pc ) can be -9 / 16π.

[0143] By applying phase rotation or phase correction, the phase rotation and correction unit (323) can obtain a phase value and a corrected phase value for each candidate orthogonal index. That is, a phase value (θ0) and a corrected phase value (θpc,0) for candidate orthogonal index 0, a phase value (θ1) and a corrected phase value (θpc,1) for candidate orthogonal index 1, and a phase value (θ2) and a corrected phase value (θpc,2) for candidate orthogonal index 2 are obtained.

[0144] The phase rotation and correction unit (323) can determine the minimum phase value (minAbsPhase) and the corresponding orthogonal index (detOCCIndex) from the acquired plurality of phase values.

[0145] The discriminator (324) can compare the second value (normPower) obtained from the differential correlator (322) with the reference power value, and compare the minimum phase value with the reference phase value. As a result of the comparison, if the two values ​​are respectively greater than the reference power value and less than the reference phase value, the discriminator (324) can determine that the detection of the presence of the control channel is successful, and the detected orthogonal index can be determined to be the orthogonal index corresponding to the minimum phase value. As a result of the comparison, if either of the two values ​​does not satisfy the above condition, the discriminator (324) can determine that the detection of the presence of the control channel has failed.

[0146] Meanwhile, the phase rotation and correction unit (323) can detect the minimum phase value (minAbsPhase) and the minimum phase index (minPhaseIdx) using Equations 15 and 16 and Table 1 instead of using Equations 5 to 7 and Equations 10 to 12 of FIG. 6. In this case, the discriminator (324) can compare the minimum phase value and the phase reference value according to Equation 14 and compare the normalized power value and the power reference value to determine whether the detection of the presence of the control channel is successful and, in the case of success, the detected orthogonal index.

[0147] The operation of the processor of the receiving side or receiving device related to Fig. 11 can utilize the technical contents mentioned in the descriptions of Figs. 1 to 6 described above.

[0148]

[0149] Figure 12 illustrates a flowchart of a control channel receiving method. The method can be performed by a receiving side of the control channel or a receiving device.

[0150] The receiving side can generate a reference signal (e.g., PSCCH DMRS) for a control channel (S1210). At this time, the orthogonal index for generating the reference signal may use a value for any of the candidate orthogonal indices. The reference signal (e.g., PSCCH DMRS) for the control channel is defined in 3GPP TS 38.211, and reference is made to Equations 1 and 2 and their related descriptions.

[0151] The receiving side can calculate the correlation between the reference signal for the generated control channel and the reference signal for the candidate control channel received from the transmitting side, and calculate the result of the differential correlation based on the calculated correlation (S1220). The result of the differential correlation includes a differential correlation value (diffCorr), a differential power value (diffEnergy), and a normalized power value (normPower), and may also include values ​​described in FIG. 5 and Equation 4. For the calculation of the correlation value, differential correlation value, and differential power value, refer to the description related to FIG. 5 and Equation 4.

[0152] The receiving side can detect the minimum phase value and its corresponding orthogonal index by applying phase rotation and / or phase compensation to the differential correlation result (S1230). The phase rotation and / or phase compensation are described in FIG. 6, Equations 5 to 7, Equations 10 to 12, Equation 16, Table 1, and the descriptions therein.

[0153] The receiving side can compare the normalized power value (normPower) calculated in S1220 and the minimum phase value detected in S1230 with the power reference value and the phase reference value, respectively, to determine whether the presence of the control channel has been successfully detected and detect the orthogonal index when the detection is successful (S1240). If the normalized power value is greater than the power reference value and the minimum phase value is less than the phase reference value, the receiving side can determine that the presence of the control channel has been successfully detected and determine the orthogonal index associated with the control channel as the index corresponding to the minimum phase value.

[0154] The control channel receiving method related to Fig. 12 can utilize the technical contents mentioned in the descriptions of Figs. 1 to 6 described above.

[0155]

[0156] The generation of the DMRS or its signal described herein may not necessarily be performed in the same manner as in mathematical equation 1. Furthermore, the names DMRS, PSCCH, control channel, etc. are merely names, and the present invention may be applied to signals for reception of specific channels.

[0157] In addition, as another aspect of the present invention, the operation of the proposal or invention described above may be implemented, performed or executed by a “computer” (a comprehensive concept including a system on chip (SoC) or a (micro) processor, etc.), or may be provided as a code or a computer-readable storage medium storing or including the code or a computer program product, and the scope of the present invention may be extended to the code or the computer-readable storage medium storing or including the code or the computer program product.

[0158]

[0159] Figures 13 to 16 show simulation results related to control channel reception.

[0160] Figures 13 and 14 illustrate the probability of not properly detecting the power and orthogonal index of a control channel when a control channel exists in a candidate subchannel, when there are 1 and 2 receiving antennas, respectively. The results are shown for a power reference value of 0.08, a number of slots used in the simulation of 5000, a TDLA30-1400 fading channel, and a transmission orthogonal index of 1.

[0161] The 3GPP standard requires that the probability of failure to properly detect the control channel power and orthogonal index be less than 1% when the SNR is 4.7 dB and two receive antennas are used. In Figure 14, it can be confirmed that the probability is less than 1% at an SNR of 4.7 dB.

[0162]

[0163] Figures 15 and 16 respectively show the probability of falsely determining that a control channel is detected when data channel interference exists in a candidate subchannel, and the probability of falsely determining that a control channel is detected when no signal exists in a candidate subchannel.

[0164] In both cases where the number of receiving antennas is 1 or 2, when there is data channel interference in the candidate subchannel, the detection error probability is less than 1% at SNR=4.7 dB (Fig. 15), and when there is no signal in the candidate subchannel, the detection error probability is less than 1% at SNR=4.7 dB (Fig. 16).

[0165] The detailed description of the preferred embodiments of the present invention disclosed above has been provided to enable those skilled in the art to implement and practice the present invention. While the above description has been made with reference to preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and variations of the present invention, as defined by the following claims, are possible. Accordingly, the present invention is not intended to be limited to the embodiments disclosed herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. In side link communication, as a method for receiving a control channel, A step of generating a reference signal for a control channel by using a first index among a plurality of candidate orthogonal indices; A step of performing a differential correlation operation on the correlation between a reference signal for a received candidate control channel and the generated reference signal; A step of applying phase rotation or phase correction to the result of the differential correlation operation to detect a minimum phase value and an orthogonal index corresponding to the minimum phase value; and A control channel receiving method, comprising a step of determining whether detection of the presence of a control channel is successful or an orthogonal index used for the control channel by using the minimum phase value and the normalized power value obtained based on the differential correlation operation.

2. In the first paragraph, applying the phase rotation is A control channel receiving method comprising applying a preset phase difference between the first index and the remaining candidate orthogonal indices to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

3. In paragraph 1, applying the phase correction is: A control channel receiving method comprising applying a maximum linear phase difference reflecting a maximum timing error corresponding to the length of a cyclic prefix of the control channel to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

4. In the first paragraph, the step of detecting the orthogonal index is: A control channel receiving method comprising the step of applying phase rotation or phase correction to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel to obtain two phase values ​​for each of the plurality of candidate orthogonal indices.

5. In the first paragraph, the normalized power value is, Proportional to the square of the accumulated sum of the differential correlation values ​​for all unit frequency resources of the above control channel, A control channel receiving method, wherein the sum of the accumulated squares of the differential correlation values ​​for all unit frequency resources of the control channel is inversely proportional to the sum of the accumulated squares of the differential correlation values ​​for all unit frequency resources of the control channel.

6. In paragraph 1, A control channel receiving method, comprising a step of determining that the detection of the presence of the control channel is successful if the minimum phase value is less than the phase reference value and the normalized power value is greater than the power reference value.

7. A control channel receiving method, comprising a step of determining an orthogonal index corresponding to the minimum phase value as an orthogonal index of the control channel in the 6th paragraph.

8. In paragraph 1, A step of applying phase rotation to the result of the operation of the differential correlation includes obtaining differential correlations for the second index and the third index among the plurality of candidate orthogonal indices, The result of the differential correlation calculation for the above second index is , The result of the differential correlation calculation for the above third index is , diffCorr is the result of differential correlation calculation for the first index, is the phase rotation value for the second index, A control channel receiving method, wherein the phase rotation value for the third index is:

9. In paragraph 8, A step of applying phase correction to the operation result of the differential correlation to which the phase rotation is applied, thereby obtaining a phase correction result of the differential correlation for the plurality of candidate orthogonal indices, The phase correction result of the differential correlation for the above first index is , The phase correction result of the differential correlation for the above second index is , The phase correction result of the differential correlation for the above third index is , diffCorr is the result of differential correlation calculation for the first index, is the phase rotation value for the second index, is the phase rotation value for the third index, A method for receiving a control channel, which is a phase correction value.

10. In side link communication, as a device for receiving a control channel, A signal generator for generating a reference signal for a control channel using a first index among a plurality of candidate orthogonal indices; A differential correlator that performs a differential correlation operation on the correlation between the reference signal for the received candidate control channel and the generated reference signal: A phase rotation and correction unit that applies phase rotation or phase correction to the result of the above differential correlation operation to detect a minimum phase value and an orthogonal index corresponding to the minimum phase value; and A device comprising a discriminator that determines whether the presence of a control channel is successfully detected or an orthogonal index used for the control channel by using the minimum phase value and the normalized power value obtained based on the differential correlation operation.

11. In the 10th paragraph, the phase rotator and compensator, A device that applies a preset phase difference between the first index and the remaining candidate orthogonal indices to the accumulated sum of differential correlation values ​​for all unit frequency resources of the above control channel.

12. In the 10th paragraph, the phase rotator and compensator, A device that applies a maximum linear phase difference reflecting a maximum timing error corresponding to the length of a cyclic prefix of the control channel to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

13. In the 10th paragraph, the phase rotator and compensator, A device that obtains two phase values ​​for each of the plurality of candidate orthogonal indices by applying phase rotation or phase correction to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

14. In the 10th paragraph, the normalized power value is, Proportional to the square of the accumulated sum of the differential correlation values ​​for all unit frequency resources of the above control channel, A device inversely proportional to the accumulated sum of the squares of the differential correlation values ​​for all unit frequency resources of the above control channel.

15. In the 10th paragraph, the discriminator, A device that determines that the detection of the presence of the control channel is successful if the minimum phase value is less than the phase reference value and the normalized power value is greater than the power reference value.

16. In the 15th paragraph, the device determines the orthogonal index corresponding to the minimum phase value as the orthogonal index of the control channel.

17. In the 10th paragraph, the phase rotator and compensator, By applying phase rotation to the result of the operation of the above differential correlation, differential correlations for the second index and the third index among the plurality of candidate orthogonal indices are obtained, The result of the differential correlation calculation for the above second index is , The result of the differential correlation calculation for the above third index is , diffCorr is the result of differential correlation calculation for the first index, is the phase rotation value for the second index, is a phase rotation value for the third index, the device.

18. In the 17th paragraph, the phase rotator and compensator, By applying phase correction to the operation result of the differential correlation to which the phase rotation is applied, the phase correction result of the differential correlation for the plurality of candidate orthogonal indices is obtained. The phase correction result of the differential correlation for the above first index is , The phase correction result of the differential correlation for the above second index is , The phase correction result of the differential correlation for the above third index is , diffCorr is the result of differential correlation calculation for the first index, is the phase rotation value for the second index, is the phase rotation value for the third index, is the phase correction value, device.

19. A computer-readable medium storing a computer program for performing a method according to any one of claims 1 to 9.

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