Apparatus and method for receiving control channel

Abstract

According to an embodiment of the present invention, proposed is an apparatus for receiving a control channel in sidelink communication, wherein the control channel is transmitted in pair with a data channel in one subframe and has a fixed size in the frequency domain, and the apparatus may comprise: a memory configured to store code for receiving the control channel; and a processor configured to execute the code to carry out operations for receiving the control channel. The operations may include: generating a reference signal for the control channel by using a first cyclic shift (CS) among a plurality of cyclic shifts (CSs); carrying out a differential correlation operation on a correlation between a reference signal for a received candidate control channel and the generated reference signal; applying phase rotation or phase correction to a result of the differential correlation operation to detect a minimum phase value and a CS corresponding to the minimum phase value; and by using the minimum phase value and a normalized power value obtained on the basis of the differential correlation operation, determining whether detection of the presence of the control channel is successful or determining a CS used for the control channel.

Description

Control channel receiving device and method

[0001] The present invention relates to wireless communication technology, and more specifically, to an apparatus and method 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 without passing through a base station. Sidelink is being considered as a solution to alleviate 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-enabled objects through wired or wireless communication. V2X may include V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian).

[0004] In 4G and 5G communication standards, a side link transmission method is used for V2X, and the side link also has a control channel and a data channel. However, unlike downlink transmission and reception between a terminal and a base station, the side link is defined so that the other party (terminal) cannot know the index used when generating the sequence code, and only candidate values ​​are provided, with the selection determined by the transmitting side.

[0005] In addition, since side links are performed in an environment where both the transmitting and receiving sides are moving, timing errors may occur; therefore, the receiving side must be able to account for this.

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

[0007] The problems of the present invention are not limited to those described above. Other problems not described above will be understood by a person skilled in the art from the description of the present invention below.

[0008] According to one embodiment of the present invention, in sidelink communication, a device for receiving a control channel having a fixed size in the frequency domain, which is transmitted in pair with a data channel in one subframe, is proposed, and the device includes a memory configured to store a code for receiving the control channel; and a processor configured to execute the code to perform an operation for receiving the control channel, wherein the operation may include generating a reference signal for the control channel using a first CS among a plurality of cyclic shifts (CS), performing a differential correlation operation on the correlation between the reference signal for the received candidate control channel and the generated reference signal, applying a phase rotation or phase correction to the result of the differential correlation operation to detect a minimum phase value and a CS corresponding to the minimum phase value, and determining whether the detection of the presence of the control channel is successful or the CS used for the control channel using the minimum phase value and a normalized power value obtained based on the differential correlation operation.

[0009] Additionally or alternatively, applying the phase rotation may include applying a preset phase difference between the first CS and the remaining candidate CS to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

[0010] Additionally or alternatively, applying the phase correction may include applying a maximum linear phase difference reflecting the maximum timing error corresponding to the length of the cyclic prefix of the control channel to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

[0011] Additionally or alternatively, detecting the CS may include obtaining two phase values ​​for each of the plurality of candidate CSs by applying phase rotation or phase correction to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

[0012] Additionally or alternatively, the normalized power value may be proportional to the square of the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel and inversely proportional to the accumulated sum of the squares of differential correlation values ​​for all unit frequency resources of the control channel.

[0013] Additionally or alternatively, the operation may include determining that the detection of the presence of the control channel is successful if the minimum phase value is smaller than the phase reference value and the normalized power value is larger than the power reference value.

[0014] Additionally or alternatively, the above operation may include determining the CS corresponding to the minimum phase value as the CS of the control channel.

[0015] Additionally or alternatively, the operation comprises: applying a phase rotation to the result of the operation of the differential correlation to obtain a differential correlation for the second CS, third CS, and fourth CS among the plurality of candidate CSs, and the result of the operation of the differential correlation for the second CS is , the operation result of the differential correlation for the above third CS is , the operation result of the differential correlation for the above 4th CS is , diffCorr is the result of the differential correlation calculation for the first CS above, θ pr,2 is the phase rotation value for the above 2 CS, θ pr,3 is the phase rotation value for the above 3rd CS, θ pr,4 may be a phase rotation value for the above 4th CS.

[0016] Additionally or alternatively, the operation includes applying a 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 CSs, and the phase correction result of the differential correlation for the first CS is The phase correction result of the differential correlation for the above second CS is The phase correction result of the differential correlation for the above 3 CS is The phase correction result of the differential correlation for the above 4th CS is diffCorr is the result of the differential correlation calculation for the first CS above, θ pr,2 is the phase rotation value for the above 2 CS, θ pr,3 is the phase rotation value for the above 3rd CS, θ pr,4 is the phase rotation value for the above 4th CS, θ pc can be a phase correction value.

[0017] According to another embodiment of the present invention, a method for receiving a control channel having a fixed size in the frequency domain, which is transmitted in pair with a data channel in one subframe in a sidelink communication is proposed, and the method may include: generating a reference signal for the control channel using a first CS among a plurality of cyclic shifts (CS); performing a differential correlation operation on the correlation between the reference signal for the received candidate control channel and the generated reference signal; detecting a minimum phase value and a CS corresponding to the minimum phase value by applying a phase rotation or phase correction to the result of the differential correlation operation; and determining whether the detection of the presence of the control channel is successful or the CS used for the control channel using the minimum phase value and a normalized power value obtained based on the differential correlation operation.

[0018] According to another embodiment of the present invention, a computer-readable medium is proposed for storing a computer program for performing the method described above.

[0019] The means of solution of the present invention described above are part of the embodiments of the present invention. Various means of solution other than the means of solution of the problem described above may be derived and understood based on the detailed description of the present invention to be explained below.

[0020] The present invention has the following effects.

[0021] The performance of detecting reception of the side link control channel in the receiving device can be improved.

[0022] The receiving device can detect reception of the side link control channel by reflecting the timing error that may occur in the side link.

[0023] The effects of the present invention are not limited to those described above. Other effects not described above may be understood by a person skilled in the art from the description of the present invention below.

[0024] 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 explain the contents of the present invention together with the detailed description.

[0025] Figure 1 illustrates a V2X communication environment.

[0026] Figure 2 illustrates resource allocation for an LTE 4G side link (SL; sidelink).

[0027] Figure 3 illustrates an example of the allocation of data channels and control channels of an LTE 4G side link.

[0028] Figure 4 illustrates the PSCCH and PSSCH transmission structure of LTE SL.

[0029] Figure 5 illustrates a procedure for detecting a control channel (or control channel DMRS).

[0030] Figure 6 illustrates a detailed functional block of differential correlation associated with the control channel DMRS.

[0031] Figure 7 illustrates the detailed structure of the phase rotation and compensator.

[0032] Figure 8 shows a PSCCH BLER in the case where detection is ideal.

[0033] Figure 9 shows the differential correlation power values ​​when a channel or signal is present or not present.

[0034] Figure 10 shows a block diagram of a transmitting device and a receiving device.

[0035] FIG. 11 shows a block diagram of the processor (32) of the receiving device (30).

[0036] Figure 12 illustrates a flowchart of a control channel reception method.

[0037] Figures 13 to 15 show simulation results related to receiving a control channel.

[0038] Embodiments of the present invention will be described below with reference to the attached drawings.

[0039] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be implemented in various other forms. The terms used in this specification are intended to aid in understanding the embodiments and are not intended to limit the scope of the present invention. Furthermore, singular forms used below include plural forms unless the phrases clearly indicate otherwise.

[0040] FIG. 1 illustrates a communication environment to which the present invention is applied.

[0041] V2X (Vehicle to Everything) refers to a communication system that includes wireless communication (V2V) between vehicles (2). V2V serves not only the basic role of informing surrounding vehicles of information such as the vehicle's location, direction, and speed, but also serves to inform them of potential hazards such as sudden braking and changes in direction.

[0042] Additionally, V2X refers to a system in which a vehicle communicates and shares with various elements on the road to enable autonomous driving, such as wireless communication between a vehicle and a network (3) (V2N), wireless communication between a vehicle and a roadside unit (RSU) (4), and wireless communication between a vehicle and traffic infrastructure (5) (V2I).

[0043] It can be used to notify each other of potential hazards through vehicle-to-vehicle communication, or to check information such as parking locations and signal change times through communication with traffic infrastructure like parking lots and traffic lights, and is considered an essential technology for perfect autonomous driving.

[0044] V2X is implemented via sidelink within 5G communication standards. Vehicles, namely the transmitting and receiving sides, transmit and receive information via sidelink.

[0045] Figure 2 illustrates resource allocation for an LTE 4G side link (SL; sidelink).

[0046] The 4G LTE (Long Term Evolution) standard specifies an SL transmission method for V2X (Vehicle to Everything) communication. SL transmission is possible only within specific pre-configured subframes, and as shown in Fig. 2, SL transmission is performed through a resource pool configured within a single frequency band.

[0047] The Tx resource pool consists of multiple subchannels, and one subchannel can consist of 13 OFDM symbols and a continuous RB (Resource Block) in the frequency axis.

[0048] In SL, PSCCH (Physical Sidelink Control Channel) is used for the transmission of SCI (Sidelink Control Information) between UEs, and PSSCH (Physical Sidelink Shared Channel) can be used for the transmission of TB (Transport Block).

[0049] Figure 3 illustrates an example of the allocation of data channels and control channels of an LTE 4G side link.

[0050] In LTE SL, adjacent PSSCH-PSCCH mode, in which PSCCH (control channel) and PSSCH (data channel) are transmitted adjacently, and non-adjacent PSSCH-PSCCH mode, in which multiple PSCCHs and multiple PSSCHs are each transmitted together, are defined.

[0051] Figure 3(a) illustrates resource allocation in adjacent PSSCH-PSCCH modes, and Figure 3(b) illustrates resource allocation in non-adjacent PSSCH-PSCCH modes.

[0052] Multiple PSCCH & PSSCH pairs can be transmitted in a single SL frequency band.

[0053] Figure 4 illustrates the PSCCH and PSSCH transmission structure of LTE SL.

[0054] As shown in Fig. 4, PSCCH and PSSCH can be transmitted as a pair within one subframe.

[0055] In the frequency domain, PSCCH has a fixed size of 2 RB, and PSSCH is set to have a size corresponding to a single or multiple subchannels. In the time domain, PSCCH and PSSCH are set to have an OFDM symbol length of 13.

[0056] PSCCH is used to transmit SCI, which is information necessary for the decoding of PSSCH transmitted together within a subframe. Therefore, for the smooth decoding of PSSCH, PSCCH must first be successfully decoded.

[0057] In both PSCCH and PSSCH, a DMRS (De-Modulation Reference Signal) is transmitted to four fixed symbols (l=2, 5, 8, 11), the DMRS is not multiplexed with data, and the receiving side can perform demodulation using the received DMRS.

[0058] Regarding the generation of PSCCH DMRS sequences, refer to the relevant section of 3GPP TS 36.211, V16.7.0. It is as follows.

[0059] [Mathematical Formula 1]

[0060]

[0061] PSCCH DMRS is generated using the PUSCH DMRS generation method, applying parameters based on the SL settings. Here, m represents the OFDM symbol index. PSCCH consists of four symbols.

[0062] This proposal considers sidelink transmission modes 3 and 4.

[0063] [Mathematical Formula 2]

[0064]

[0065] [Mathematical Formula 3]

[0066]

[0067] [Mathematical Formula 4]

[0068]

[0069] When generating PSCCH DMRS, CS(n cs,λ ) (cyclic shift) excluding the setting values ​​are fixed values ​​(n cs,λ → n cs ∵ λ=0). That is, all DMRS symbols of the transmitted PSCCH correspond to the same sequence, differing only in phase rotation due to CS.

[0070] As explained earlier, the CS(n applied to PSCCH DMRS) cs,λ ) is configured so that the transmitting UE randomly selects from {0, 3, 6, 9}, so the receiving UE cannot know the CS applied to the transmitted PSCCH DMRS.

[0071] This proposal proposes a method for a receiving UE to receive PSCCH or PSCCH DMRS transmitted from a transmitting UE.

[0072] This proposal aims to propose a method for receiving PSCCH or PSCCH DMRS that satisfies the following requirements.

[0073] PSCCH can be transmitted on all subchannels, and the receiving UE does not know the CS applied to the transmitted PSCCH DMRS. Therefore, for every received subframe, the receiving UE must determine whether there is a PSCCH on each subchannel and also detect the CS transmitted at the same time.

[0074] In V2X communication methods, since UEs (vehicles, RSUs, etc.) communicate with each other, a certain level of timing error may occur; therefore, the receiving UE must be able to reliably detect the presence of the PSCCH and the transmitted CS even if such a level of timing error occurs.

[0075] If the timing error is very large, the PSCCH may be received beyond the range of the CP (cyclic prefix); even in this case, to extend coverage, it must be possible to robustly detect the presence of the PSCCH and the transmitted CS as long as demodulation performance is guaranteed.

[0076] Therefore, this proposal aims to propose a method capable of robustly detecting the presence or absence of a PSCCH and the CS for the transmitted PSCCH, both within and outside the CP range (up to the extent that demodulation performance is guaranteed).

[0077] FIG. 5 illustrates a procedure for detecting a control channel (or control channel DMRS). The procedure is performed at the receiving side of the control channel (or control channel DMRS).

[0078] Self-DMRS generation (11) generates a signal generation method of a pre-agreed method, for example, a PSCCH DMRS defined in a standard document, based on the relevant parameters, and uses CS=0 (i.e., the first CS).

[0079] The differential correlation, phase rotation, and correction (12) are related to calculating the correlation and obtaining the differential correlation using the candidate control channel DMRS received from the transmitting side and the control channel DMRS generated by the receiving side, 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.

[0080] The detection determination (13) is about determining whether a control channel (or control channel DMRS) exists by comparing the phase rotation and corrected value with a reference value (threshold value), and determining CS if a control channel exists.

[0081] Hereinafter, detailed information for detecting the control channel (or control channel DMRS) and the CS of the control channel will be explained with reference to FIGS. 6 and 7.

[0082] Figure 6 illustrates a detailed functional block of differential correlation associated with the control channel DMRS.

[0083] Referring to FIG. 6, the differential correlation consists of a receiving control channel DMRS, a generated control channel DMRS correlator (121), and a DMRS differential correlator (122). As shown in FIG. 7, 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).

[0084] The correlator (121) is a receiving control channel DMRS ( Control channel DMRS using ) and candidate CS (CS=0) generated at the receiving side ( Calculates the correlation of ). To do this, the receiving side uses the control channel DMRS for candidate CS (CS=0) ( We need to create ), which is as follows.

[0085] [Mathematical Formula 5]

[0086]

[0087] For the pseudo-random sequence c(n), refer to the section on DMRS for PSCCH in 3GPP TS 36.211.

[0088] Receive Control Channel DMRS ( ) and CS=0 generated by the receiving side The operation of the correlation is class It can be expressed as the product of the complex conjugates of . More specifically, It can be expressed as.

[0089] Received For CS=0 The operation for correlation can be performed as follows.

[0090] [Mathematical Formula 6]

[0091]

[0092] At this time, is the number of PSCCH DMRS RE (=24), is the RB number (number) where CCH starts in the resource pool, silver Antenna port, Number OFDM symbol, Indicates the PSCCH DMRS received from the sub-carrier, represents the number of receiving antennas. * represents the complex conjugate operator.

[0093] The calculation result is a total * 4 * It can be seen that it is obtained as a dog.

[0094] After this, Using (Differential correlation) and The (normalized power value) can be obtained as follows.

[0095] [Mathematical Formula 7]

[0096]

[0097] At this time, represents the number of PSCCH DMRS symbols (=4).

[0098] As explained earlier, For every OFDM symbol (l) (24) are obtained, and since mathematical formula 7 is an operation between them, the number of operations is 1 less than that, so m is set as above, and 24-1=23 operations are performed.

[0099] The first value (diffCorr) corresponds to the result of the differential correlation operation for CS=0, and if we examine the operation of the first value (diffCorr), at consecutive resource locations (subcarriers) It is the autocorrelation operation and the cumulative sum thereof. If the phase (angle) of the result of this operation is close to 0, the control channel DMRS generated at the corresponding CS value, receiving antenna port, and resource location. A received signal It is highly likely to be the same as.

[0100] In Equation 14 to be described later, the phase (angle) range for determining the identity of two signals is set to within π / 4 in absolute value, and this range is merely an example. The receiving side performs this determination of the identity of two signals for all candidate CS values, receiving antenna ports, time resources (i.e., OFDM symbols), and frequency resources (i.e., subcarriers), but in the case of candidate CS, control channel DMRS is not generated for all candidate CS values, but rather a pre-set phase difference between candidate CSs is used as described later.

[0101] When the first value (diffCorr) is obtained, a set of phase values ​​of differential correlation values ​​for multiple candidate CSs using the first value is obtained as follows. As previously explained, the receiving side only generated a control channel DMRS for a specific candidate CS (CS=0) and performed correlation operations with the receiving control channel DMRS, and did not perform operations for the remaining candidate CSs (CS=3, 6, 9). Through the following process, the phase values ​​of differential correlations for the remaining candidate CSs can be obtained without generating control channel DMRS for the remaining candidate CSs.

[0102] 1) First step (Obtaining the phase value of the differential correlation for all candidate CSs)

[0103] Referring to mathematical equation 4, CS=0 has a phase difference of 1 / 2 π with CS=3, a phase difference of π with CS=6, and a phase difference of 3 / 2 π with CS=9.

[0104] Therefore, the differential correlation value of CS=3 will have a phase difference of 1 / 2π with the differential correlation value of CS=0, the differential correlation value of CS=6 will have a phase difference of π with the differential correlation value of CS=0, and the differential correlation value of CS=9 will have a phase difference of 3 / 2π (or -1 / 2π) with the differential correlation value of CS=0.

[0105] Accordingly, as shown in FIG. 7, θ0, θ1, θ2, and θ3 can be obtained as follows. θ0 represents the phase value of the differential correlation between the received control channel DMRS and the control channel for CS=0, θ1 represents the phase value of the differential correlation between the received control channel DMRS and the control channel for CS=3, θ2 represents the phase value of the differential correlation between the received control channel DMRS and the control channel for CS=6, and θ3 represents the phase value of the differential correlation between the received control channel DMRS and the control channel for CS=9.

[0106] [Mathematical Formula 8]

[0107]

[0108] [Mathematical Formula 9]

[0109]

[0110] [Mathematical Formula 10]

[0111]

[0112] [Mathematical Formula 11]

[0113]

[0114] In other words, the result of the differential correlation calculation for CS=3 is It can be expressed as, and the result of the differential correlation operation for CS=6 is It can be expressed as such, and the result of the differential correlation operation for CS=9 is It can be expressed as. Here, the phase rotation value (θ pr,1 , θ pr,2 , θ pr,3 ) can be 1 / 2π, π, and -1 / 2π, respectively.

[0115] As expressed in mathematical formulas 9 to 11, the present proposal generates a control channel DMRS for all CSs and compares it with the received control channel DMRS (correlation operation and differential correlation of the correlation value), generates only the control channel DMRS for CS=0 and compares it with the received control channel DMRS to obtain the phase value of the differential correlation, and for the remaining candidate CS=3, 6, and 9, applies a phase rotation value to the differential correlation for candidate CS=0 to obtain the phase value of the differential correlation.

[0116] 2) Second process (Obtaining phase values ​​of differential correlations reflecting timing errors for all candidate CSs)

[0117] As explained earlier, since sidelink communication environments are expected to frequently involve transmission and reception operations while the transmitting and receiving sides are in motion, they must be robust against timing errors. Phase correction is required to account for these timing errors.

[0118] When a timing error exists, the linear phase difference between two consecutive subcarriers can be defined as follows.

[0119] [Mathematical Formula 12]

[0120]

[0121] Here, if FFT_SIZE is 1024 and the subcarrier spacing is 30 kHz, the length of the normal cyclic prefix (CP) corresponds to 72 samples.

[0122] By taking into account timing errors outside the CP range where demodulation performance is guaranteed, TO can be applied up to 128 samples. If phase correction is not applied, detection within the CP range is possible.

[0123] If a maximum of 128 samples of TO occur, the maximum linear phase difference that can occur between two consecutive DMRS is as follows.

[0124] [Mathematical Formula 13]

[0125]

[0126] Therefore, assuming an ideal channel situation, a phase correction corresponding to π / 4, which corresponds to the maximum linear phase difference value, is 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 128 samples occurs.

[0127] Accordingly, the phase values ​​reflecting phase correction considering timing error in θ0, θ1, θ2, and θ3 are as follows.

[0128] [Mathematical Formula 14]

[0129]

[0130] [Mathematical Formula 15]

[0131]

[0132] [Mathematical Formula 16]

[0133]

[0134] [Mathematical Formula 17]

[0135]

[0136] In other words, the phase correction result of the differential correlation for candidate CS=0 is It can be expressed as, and the phase correction result of the differential correlation for candidate CS=3 is It can be expressed as, and the phase correction result of the differential correlation for candidate CS=6 is It can be expressed as, and the phase correction result of the differential correlation for candidate CS=9 is It can be expressed as. Here, the phase correction value (θ pc ) can be -π / 4.

[0137] Returning to Equation 7 and examining the calculation of the second value (normPower), diffEnergy (differential power) at consecutive resource locations (subcarriers) It is the squared value (power value) of the differential correlation result and the cumulative sum thereof. The second value (normPower) is the square of the first value, diffEnergy, and the number of times the differential correlation operation (or It corresponds to the result of dividing by the product of ).

[0138] As the output of the phase rotation corrector (123) shown in FIG. 7, θ0, θ1, θ2, θ3, θ pc,0 , θ pc,1 , θ pc,2 , θ pc,3 These are obtained and used as inputs to the detection discriminator (13).

[0139] The detection discriminator (13) determines whether the received candidate control channel DMRS is a control channel DMRS generated by a CS. At this time, not only the first value (diffCorr) based on 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. Ultimately, the detection discriminator (13) considers not only the phase value of the differential correlation but also the power value.

[0140] 1) First process - Detection of the CS index (or CS value) having the minimum phase value

[0141] [Mathematical Formula 18]

[0142]

[0143] The first process is to determine the minimum phase value (minAbsPhase) and the corresponding CS value. As described with reference to FIGS. 5 through 7, the obtained θ0, θ1, θ2, θ3, θ pc,0 , θ pc,1 , θ pc,2 , θ pc,3 Select the smallest value among them and determine the CS value of that value. This process is expressed in Equation 18.

[0144] 2) Second process - Comparison of minimum phase value and phase reference value, and comparison of power value and power reference value

[0145] The minimum phase value does not necessarily imply the success of detection of the control channel or the control channel DMRS. To this end, the receiving side may compare the previously acquired second value (normPower) with a power reference value and compare the minimum phase value with a phase reference value.

[0146] 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 CS at that time corresponds to detCSIndex(0, 1, 2 or 3) (corresponding to CS=0, 3, 6, 9, respectively).

[0147] Otherwise, the receiving side is determined to have failed to detect the control channel or the control channel DMRS.

[0148] Here, the power reference value (Thpower) and the phase reference value (π / 4) can also be expressed in other terms and correspond to values ​​that can be set by the transmitting and receiving system or the receiving side. This process is expressed in Equation 19.

[0149] [Mathematical Formula 19]

[0150]

[0151] At this time, TH power represents the settable threshold. (e.g., 0.065)

[0152] Figure 8 shows a PSCCH BLER in the case where detection is ideal.

[0153] Figure 9 shows the differential correlation power values ​​when PSCCH is present, when PSSCH interference is present, and when no signal is present. These are illustrated in Figures 9 (a), (b), and (c), respectively.

[0154] Figures 9 (a) and (b) show the differential correlation power values ​​when normalization is applied. It is confirmed that when there is an interference signal from PSSCH, the normalized power values ​​range from 0.0 to 0.082, and when there is no signal, the normalized power values ​​range from 0.0 to 0.04. Accordingly, an appropriate power reference value (Thpower) can be set for cases where PSCCH is present and cases where it is not (PSSCH interference signal and cases where there is no signal).

[0155] Figure 10 shows a block diagram of a transmitting device and a receiving device.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] In addition, the memory (21, 31) of each device (20, 30) may store code for operation or data processing for transmitting or receiving a control channel according to the present invention described above.

[0161] The transmitting device (20) and the receiving device (30) can each be mounted on equipment or devices for V2X communication, such as a vehicle or an RSU (road side unit).

[0162] The transmitting device (20) can transmit a sidelink channel to the receiving device (30) via the 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 receiving the control channel is required to receive the data channel.

[0163] However, in the sidelink, instead of using a pre-arranged CS (cyclic shift) value between the transmitting device (20) and the receiving device (30), it is designed so that one of the pre-set parameter sets (i.e., multiple CS candidates) is randomly determined by the transmitting device (20). Accordingly, the receiving device (30) needs to receive the sidelink control channel efficiently 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 account is required.

[0164] To this end, the content of the technology described with reference to FIGS. 5 to 7 described above can be performed in the receiving device (30). According to this technology, the detection of the control channel and the used CS can be determined without attempting to decode all signals received in the candidate resource area.

[0165] FIG. 11 illustrates a block diagram of a processor (32) of a receiving device (30). The receiving device (30) performs operations related to the detection of a control channel or control channel DMRS described with reference to FIG. 5 through 7 in side-link communication. That is, the processor (32) is a device configured to receive a control channel or control channel DMRS.

[0166] The processor (32) may include a signal generator (321), a differential correlator (322), a phase rotation and correction unit (323), and a discriminator (324).

[0167] The signal generator (321) can generate a demodulation reference signal (DMRS) for each candidate CS value. The generation of the demodulation reference signal is performed based on the previously described mathematical equations 1 through 4 and related explanations.

[0168] The differential correlator (322) can perform a correlation operation between the candidate control channel DMRS received from the transmitting device (20) through the transceiver (33) and the DMRS generated by the signal generator (321). The differential correlator (322) can perform the result of the correlation operation ( A differential correlation operation can be performed on ). Then, the differential correlator (322) can accumulate the results of the differential correlation to obtain a first value (diffCorr).

[0169] Additionally, the differential correlator (322) can calculate the squared 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 constant.

[0170] The phase rotation and correction device (323) can apply phase rotation or phase correction to the acquired first value (diffCorr) as shown in FIG. 7 and using Equations 8 to 11 and Equations 13 to 17. Phase rotation value (θ pr,1 , θ pr,2 , θ pr,3 ) can be 1 / 2π, π, and -1 / 2π, respectively. Also, the phase correction value (θ pc ) can be -π / 4.

[0171] 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 CS. That is, a phase value (θ0) and a corrected phase value (θ0) for candidate CS=0. pc,0 ), phase value (θ1) for candidate CS=3 and corrected phase value (θ pc,1 ), phase value (θ2) and corrected phase value (θ) for candidate CS=6 pc,2 ), phase value (θ3) for candidate CS=9 and corrected phase value (θ pc,3 ) is obtained.

[0172] The phase rotation and correction device (323) can determine the minimum phase value (minAbsPhase) and the corresponding CS index or CS value (detCSIndex) from the acquired multiple phase values.

[0173] The discriminator (324) can compare the second value (normPower) obtained from the differential correlator (322) with the reference power value, and can compare the minimum phase value with the reference phase value. As a result of the comparison, if both values ​​are each greater than the reference power value and smaller than the reference phase value, the discriminator (324) determines that the detection of the presence of the control channel has succeeded, and if the detected CS index or CS corresponds to the minimum phase value, it can determine that it is the CS used for the control channel transmission. As a result of the comparison, if either of the two values ​​does not satisfy the above conditions, the discriminator (324) can determine that the detection of the presence of the control channel has failed.

[0174] The operation of the processor of the receiving side or receiving device related to Fig. 11 may utilize the technical content mentioned in the description of Figs. 1 to 7 described above.

[0175] FIG. 12 illustrates a flowchart of a control channel reception method. The method may be performed by a receiving side or a receiving device of the control channel.

[0176] The receiving side may generate a reference signal for the control channel (e.g., PSCCH DMRS) (S1210). In this case, the CS for generating the reference signal may use a value for any one of the candidate CSs. The reference signal for the control channel (e.g., PSCCH DMRS) is defined in 3GPP TS 38.211, and reference should be made to Equations 1 through 4 and the related descriptions.

[0177] 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. 6 and Equation 7. For the calculation of the correlation value, differential correlation value, and differential power value, refer to the explanation related to FIG. 6 and Equation 7.

[0178] The receiving side can detect the minimum phase value and the corresponding CS by applying phase rotation and / or phase correction to the differential correlation result (S1230). For phase rotation and / or phase correction, refer to FIG. 7, Equations 8 to 11, Equations 13 to 17 and the description based thereon.

[0179] The receiving side compares 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 detection of the existence of the control channel was successful and to detect the CS when the detection is successful (S1240). If the normalized power value is greater than the power reference value and the minimum phase value is smaller than the phase reference value, the receiving side determines that the detection of the existence of the control channel was successful and can determine the CS associated with the control channel as the CS corresponding to the minimum phase value.

[0180] The control channel receiving method related to Fig. 12 may utilize the technical content mentioned in the description of Figs. 1 to 7 described above.

[0181] The generation of the DMRS or the signal described in this specification may not necessarily be carried out in the same manner as Equations 1 to 4 or related standard documents. Furthermore, names such as DMRS, PSCCH, and control channel are merely names, and the present invention may be applied to signals for receiving a specific channel.

[0182] In addition, as another aspect of the present invention, the operation of the above-described proposal or invention may be provided as code that can be implemented, practiced, or executed by a "computer" (a comprehensive concept including a system on chip (SoC) or (micro)processor, etc.), or as a computer-readable storage medium or computer program product that stores or contains said code, and the scope of the present invention may be extended to said code or as a computer-readable storage medium or computer program product that stores or contains said code.

[0183] Figures 13 to 15 show simulation results related to receiving a control channel.

[0184] Through computer simulation, the detection performance of the method proposed in this invention was measured, and the detection performance was measured under the following situations.

[0185] 1) Measure detection performance when PSCCH is present in the candidate subchannel (Fig. 13)

[0186] 2) Measure detection performance when PSSCH is present in the candidate subchannel and enters as an interference signal (Fig. 14)

[0187] 3) When no signal is present in the candidate subchannel, measure the detection performance (Fig. 15)

[0188] <Simulation Environment>

[0189] Bandwidth: 10MHz, SCS (sub-carrier spacing): 15K, Normal CP length: 72 samples

[0190] AWGN (Additive White Gaussian Noise) environment

[0191] Timing offset (TO): 0 ~ 136 samples

[0192] Figures 13 and 14 show the simulation results for a case where there are 2 receiving antennas and a PSCCH generated with CS=3, the power reference value (Thpower) is 0.065, the number of subframes used in the simulation is 10,000, and the AWGN & CNR is 5.0dB.

[0193] Figure 13 shows the results when TO is 0 to 128 samples, and Figure 14 shows the results when TO is 116 to 136 samples.

[0194] Through the proposed method, PSCCH detection and demodulation are performed up to 128 sample TOs, and it was confirmed that PSCCH detection is 100% successful up to 128 sample TOs.

[0195] Referring to Fig. 15, it can be seen that the false alarm probability is less than 1% in the range of samples 0 to 136. The 3GPP standard requires that the probability of failing to properly detect control channel power and CS be less than 1% when the SNR is 4.7dB and there are two receiving antennas.

[0196] The detailed description of the preferred embodiments of the present invention disclosed as described above is provided so that a person skilled in the art can implement and practice the present invention.

[0197] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention as described in the following claims.

[0198] Accordingly, the present invention is not intended to be limited to the embodiments shown herein, but to be given the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. In sidelink communication, a device for receiving a control channel having a fixed size in the frequency domain, which is transmitted in pair with a data channel in one subframe, A memory configured to store a code for receiving the above control channel; and It includes a processor configured to execute the code to perform an operation for receiving the control channel, and The above operation is: A reference signal for the control channel is generated using a first CS among a plurality of cyclic shifts (CS), and A differential correlation operation is performed on the correlation between the reference signal for the received candidate control channel and the generated reference signal, and Phase rotation or phase correction is applied to the result of the above differential correlation operation to detect a minimum phase value and a CS corresponding to the minimum phase value, and, A device comprising determining whether the presence of a control channel is detected successfully or whether a CS used for the control channel is determined using the minimum phase value and a normalized power value obtained based on the differential correlation operation.

2. In paragraph 1, applying the phase rotation is, A device comprising applying a preset phase difference between the first CS and the remaining candidate CS to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

3. In paragraph 1, applying the above phase correction is, A device 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 paragraph 1, detecting the CS is, A device comprising obtaining two phase values ​​for each of the plurality of candidate CSs by applying phase rotation or phase correction to the accumulated sum of differential correlation values ​​for all unit frequency resources of the control channel.

5. In paragraph 1, the normalized power value is, It is proportional to the square of the accumulated sum of differential correlation values ​​for all unit frequency resources of the above control channel, and A device inversely proportional to the accumulated sum of the squared differential correlation values ​​for all unit frequency resources of the above control channel.

6. In paragraph 1, the above operation is: A device comprising determining that the detection of the presence of the control channel is successful if the minimum phase value is smaller than the phase reference value and the normalized power value is larger than the power reference value.

7. In paragraph 6, the above operation is: A device comprising determining the CS corresponding to the above minimum phase value as the CS of the above control channel.

8. In paragraph 1, the above operation is: The method includes applying a phase rotation to the result of the operation of the above differential correlation to obtain a differential correlation for the second CS, third CS, and fourth CS among the plurality of candidate CSs, and The result of the differential correlation operation for the above second CS is , The result of the differential correlation operation for the above third CS is , The result of the differential correlation operation for the above 4th CS is , diffCorr is the result of the differential correlation calculation for the first CS above, θ pr,2 is the phase rotation value for the above 2 CS, θ pr,3 is the phase rotation value for the above 3rd CS, θ pr,4 is a device that is the phase rotation value for the above 4th CS.

9. In paragraph 8, the above operation is: It includes applying phase correction to the operation result of the differential correlation to which the above phase rotation is applied, and obtaining a phase correction result of the differential correlation for the plurality of candidate CSs. The phase correction result of the differential correlation for the above first CS is The phase correction result of the differential correlation for the above second CS is The phase correction result of the differential correlation for the above 3 CS is The phase correction result of the differential correlation for the above 4th CS is diffCorr is the result of the differential correlation calculation for the first CS above, θ pr,2 is the phase rotation value for the above 2 CS, θ pr,3 is the phase rotation value for the above 3rd CS, θ pr,4 is the phase rotation value for the above 4th CS, θ pc is a device, which is a phase correction value.

10. A method for receiving a control channel having a fixed size in the frequency domain, which is transmitted in pair with a data channel in one subframe in sidelink communication, A step of generating a reference signal for the control channel using a first CS among a plurality of cyclic shifts (CS); A step of performing a differential correlation operation on the correlation between the reference signal for the received candidate control channel and the generated reference signal; A step of detecting a minimum phase value and a CS corresponding to the minimum phase value by applying a phase rotation or phase correction to the result of the above differential correlation operation; and A method comprising the step of determining whether the presence of a control channel is detected successfully or the CS used for the control channel using the minimum phase value and the normalized power value obtained based on the differential correlation operation.

11. A computer-readable medium storing a computer program for performing the method according to paragraph 10.

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