Channel blind detection method in long term evolution system

Abstract

The invention provides a channel blind detection method in a long term evolution system, which belongs to the technical field of communication, and comprises the following steps: acquiring grouping metric values corresponding to antenna port number candidates, and determining a detection sequence of the antenna port number candidates; for each wireless frame, according to the plurality of scrambling code candidates, sequentially performing scrambling code descrambling processing on log-likelihood ratios obtained by demodulating the physical broadcast channel, calculating correlation values, and determining a scrambling code detection sequence of the plurality of scrambling code candidates of the current wireless frame according to a correlation value sequence; and according to the scrambling code detection sequence of all wireless frames in the sending period of the physical broadcast channel, combining the log-likelihood ratios after the scrambling code candidates corresponding to the non-zero correlation values are descrambled, and carrying out physical broadcast channel detection. The method has the advantages that the number of antenna ports and the scrambling code detection sequence are sequenced, the number of blind detection times is reduced, the number of PBCH detection times can be effectively reduced even in a low signal-to-noise ratio interval, the number of detection times in a high signal-to-noise ratio interval is reduced to one from four at most, and therefore the implementation complexity and power consumption of the terminal are reduced.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and in particular, to a method for blind detection of channels in a Long Term Evolution (LTE) system. Background Art

[0002] In a Long Term Evolution (LTE) system, the Physical Broadcast Channel (PBCH) carries system information such as cell IDs and is used for the cell search process. The PBCH channel carries the Broadcast Channel (BCH), uses Quadrature Phase Shift Keying (QPSK) modulation, has a transmission block duration of 40 ms, and the terminal needs to perform blind detection and demodulation.

[0003] The PBCH channel transmission process is as follows: The 24-bit Master Information Block (MIB) is encoded by Cyclic Redundancy Check (CRC) to generate a 16-bit CRC scrambled code; subsequently, according to the number of antenna ports configured for the cell (1, 2, or 4), the corresponding CRC scrambled code is selected to scramble the CRC; next, the MIB and the CRC are combined into a 40-bit code block, which is further extended to a 120-bit code block through convolutional coding. This 120-bit code block undergoes interleaving and is repeated multiple times, finally forming a sequence of 1920-bit Normal Cyclic Prefix (NCP) or 1728-bit Extended Cyclic Prefix (ECP); subsequently, the PBCH scrambling code updated every 40 ms (4 radio frames, where 1 radio frame occupies 10 ms) is used to scramble this sequence. This scrambling code depends only on the cell ID, ensuring the uniqueness and security of the data. When the base station sends the PBCH, it divides it into 4 equal parts and sends one part in each radio frame. Since the MIB only contains the high 8 bits of the 10-bit System Frame Number (SFN), the MIB information will change after more than 40 ms. In addition, the low 2 bits of the SFN are reflected by dividing the PBCH scrambling code into 4 equal parts.

[0004] When the terminal decodes the PBCH, while obtaining the MIB, it is necessary to correctly detect the number of antenna ports used when the PBCH is transmitted and the phase of the scrambling code (i.e., which one of the 4 scrambling codes). The Cell Reference Signal (CellRS or simply CRS) is used for the channel estimation value required for PBCH detection. However, during resource mapping, regardless of the actual number of antenna ports used during transmission, it is necessary to avoid the subcarriers where the CRS configured for 4 antenna ports during transmission is located. Taking NCP as an example, the PBCH transmission process is as shown in Chinese Patent CN102904668A's Figure 4 As shown, for the Cell RS subcarriers corresponding to each antenna port during NCP configuration, the Cell RS of antenna port 1 corresponds to that of antenna port 0, the Cell RS of antenna port 2 corresponds to those of antenna ports 0 and 1, and the Cell RS of antenna port 4 corresponds to those of antenna ports 0, 1, 2, and 3.

[0005] Traditional blind detection methods perform PBCH channel decoding by attempting 3 combinations of the number of antenna ports (1 / 2 / 4) and 4 scrambling code combinations until the PBCH is correctly decoded. When the number of antenna ports and SFN of the cell are unknown, this method requires at most 12 detections regardless of the signal-to-noise ratio, which increases the implementation complexity of the terminal and the power consumption of the terminal. In the low signal-to-noise ratio range, it is necessary to continuously receive the PBCH of 4 radio frames and combine them to increase the probability of correct decoding.

[0006] Although some journal articles have proposed methods for detecting the number of antenna ports based on signal-to-noise ratio estimation. For example, the journal article "Design and Implementation of Antenna Port Number Detection Method in LTE System" (2013, 25(6): 716 - 737) estimates the signal-to-noise ratio of each antenna port, then compares it with a threshold to determine the number of antenna ports. The simulation shows that in the low signal-to-noise ratio range, the accuracy is relatively low, and in the high signal-to-noise ratio range, this algorithm can accurately identify the number of antenna ports. Therefore, the number of antenna ports is still blindly detected in the low signal-to-noise ratio range.

[0007] Another example is that the problems existing in the journal articles "An Improved Antenna Port Number Detection Algorithm in LTE System" (2016, 56(11): 1229 - 1234) and "LTE Antenna Port Number Detection Algorithm Based on Kalman Autoregression" (2019, 31(3): 331 - 339) are the same as those of the above journal article. The number of antenna ports is still blindly detected in the low signal-to-noise ratio range, and regardless of which signal-to-noise ratio range, 4 scrambling codes still need to be blindly detected for each number of antenna ports. That is, in the low signal-to-noise ratio range, the accuracy is still relatively low.

[0008] However, in the low signal-to-noise ratio range where the working signal-to-noise ratio of the PBCH specified by the LTE standard is located, the detection accuracy of the number of antenna ports is relatively low, and the complexity of blind detection is still very high at this time. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a method for blind channel detection in a Long Term Evolution (LTE) system.

[0010] The technical problems solved by the present invention can be realized by the following technical solutions:

[0011] A method for blind channel detection in a Long Term Evolution system, comprising:

[0012] Step S1, obtaining grouped metric values corresponding to antenna port number candidates, and determining the detection sorting of multiple antenna port number candidates according to the grouped metric values;

[0013] Step S2, for each radio frame, performing scrambling and descrambling processing on the log-likelihood ratio obtained by demodulating the physical broadcast channel in the radio frame in sequence according to a plurality of scrambling code candidates preset, calculating the correlation values of the log-likelihood ratios after descrambling for each scrambling code candidate, and then determining the scrambling detection sorting of multiple scrambling code candidates of the current radio frame according to the correlation value sorting;

[0014] Step S3, according to the scrambling detection sorting of all radio frames within one transmission period of the physical broadcast channel, combining the log-likelihood ratios after descrambling of scrambling code candidates corresponding to non-zero correlation values, and using the combined log-likelihood ratios to detect the physical broadcast channel for the antenna port.

[0015] Preferably, the step S1 includes:

[0016] Step S11, grouping the metric values corresponding to the antenna ports according to the antenna port number candidates to obtain grouped metric values corresponding to each antenna port number candidate;

[0017] Step S12, comparing each grouped metric value with a decision threshold to determine the detection sorting of multiple antenna port number candidates.

[0018] Preferably, the antenna port number candidates are 1, 2, or 4, and the grouped metric values include a first grouped metric value corresponding to the first antenna port, a second grouped metric value corresponding to the second antenna port, and a third grouped metric value corresponding to the third and fourth antenna ports;

[0019] The step S12 includes:

[0020] Step S121, determining whether the third grouped metric value is not less than the decision threshold:

[0021] If so, set the detection priority of the candidate number of antenna ports corresponding to the third grouped metric value to the highest, determine the detection priorities of the candidate number of antenna ports being 1 and the candidate number of antenna ports being 2 according to the magnitudes of the first grouped metric value and the second grouped metric value, and proceed to step S124;

[0022] If not, proceed to step S122;

[0023] Step S122: Determine whether the second grouped metric value is not less than the decision threshold:

[0024] If so, set the detection priority of the candidate number of antenna ports corresponding to the second grouped metric value to the highest, determine the detection priorities of the candidate number of antenna ports being 1 and the candidate number of antenna ports being 4 according to the magnitudes of the first grouped metric value and the third grouped metric value, and proceed to step S124;

[0025] If not, proceed to step S123;

[0026] Step S123: Determine whether the first grouped metric value is not less than the decision threshold:

[0027] If so, set the detection priority of the candidate number of antenna ports corresponding to the first grouped metric value to the highest, determine the detection priorities of the candidate number of antenna ports being 2 and the candidate number of antenna ports being 4 according to the magnitudes of the second grouped metric value and the third grouped metric value, and proceed to step S124;

[0028] If not, determine the detection priorities of the candidate number of antenna ports being 1, the candidate number of antenna ports being 2, and the candidate number of antenna ports being 4 according to the magnitudes of the first grouped metric value, the second grouped metric value, and the third grouped metric value;

[0029] Step S124: Determine the detection order according to the detection priorities of each candidate number of antenna ports.

[0030] Preferably, the method for determining the judgment threshold is:

[0031] P TH = max(ασ 2 , βP0)

[0032] where α represents the amplification factor of the noise power σ 2 , α ≥ 1; β represents the scaling factor of the first grouped metric value P0 corresponding to the first antenna port, β ≥ 0; P TH represents the judgment threshold.

[0033] Preferably, step S2 includes:

[0034] Step S21, generate a scrambling sequence, perform equal division processing on the scrambling sequence to obtain multiple scrambling candidates;

[0035] Step S22, demodulate the physical broadcast channel in the radio frame to obtain a log-likelihood ratio;

[0036] Step S23, successively use multiple scrambling candidates to descramble the log-likelihood ratio to obtain the descrambled log-likelihood ratios corresponding to the multiple scrambling candidates;

[0037] Step S24, perform correlation calculation on the descrambled log-likelihood ratios corresponding to each scrambling candidate to obtain the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates;

[0038] Step S25, sort the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates, and determine the scrambling detection sorting of the multiple scrambling candidates of the current radio frame according to the correlation value sorting.

[0039] Preferably, the calculation method of the correlation value in step S2 is:

[0040]

[0041] wherein, llr des represents the descrambled log-likelihood ratio, the subscript t represents the scrambling candidate index; the subscript k represents the correlation point index, k = 0,..., N - 1, N represents the correlation length, and the subscript S t represents the correlation interval.

[0042] Preferably, after the scrambling and descrambling process in step S2, it further includes: storing the demodulated log-likelihood ratio into the log-likelihood ratio storage space according to the first-in first-out storage rule;

[0043] Step S3 includes:

[0044] Step S301A, according to the multiple scrambling candidates, successively perform scrambling and descrambling processing on the demodulated log-likelihood ratio stored in the log-likelihood ratio storage space to obtain the descrambled log-likelihood ratios of the multiple scrambling candidates;

[0045] Step S302A, perform correlation value calculation on the descrambled log-likelihood ratios of the multiple scrambling candidates to obtain the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates;

[0046] Step S303A, sort the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates, and determine the scrambling detection sorting of all radio frames within one transmission period of the physical broadcast channel according to the correlation value sorting.

[0047] Preferably, after calculating the relevant values in step S2, the method further includes: storing the relevant values obtained by descrambling the corresponding log-likelihood ratios of multiple scrambling code candidates into a relevant value storage space in sequence according to the first-in first-out storage rule;

[0048] Step S3 includes:

[0049] Step S301B: sorting the cumulative relevant values corresponding to each scrambling code candidate in the relevant value storage space to obtain a cumulative relevant value sorting;

[0050] Step S302B: determining a scrambling code detection sorting for all radio frames within one transmission period of the physical broadcast channel according to the cumulative relevant value sorting.

[0051] Preferably, the cumulative relevant value is:

[0052]

[0053] where CORbuffer represents a relevant value cache matrix; l represents a matrix element; COR accu0 represents the cumulative relevant value corresponding to the first scrambling code candidate; COR accu1 represents the cumulative relevant value corresponding to the second scrambling code candidate; COR accu2 represents the cumulative relevant value corresponding to the third scrambling code candidate; COR accu3 represents the cumulative relevant value corresponding to the fourth scrambling code candidate.

[0054] Preferably, in step S3, the detection of the physical broadcast channel includes:

[0055] Step S31: performing rate dematching on the combined log-likelihood ratios;

[0056] Step S32: performing tail-biting deconvolution on the log-likelihood ratios after rate dematching;

[0057] Step S33: performing CRC check on the log-likelihood ratios after tail-biting deconvolution, and if the check passes, the decoding of the physical broadcast channel is successful.

[0058] The advantages or beneficial effects of the technical solution of the present invention are as follows:

[0059] By sorting the number of antenna ports used during transmission and the detection order of scrambling codes, that is, first sorting the detection of the number of antenna ports, then sorting the detection of the scrambling codes corresponding to each radio frame within the period, and finally sorting the detection of the scrambling codes during the combination of the log-likelihood ratios between the radio frames within the period, the present invention reduces the number of blind detections. Even in the low signal-to-noise ratio range, it can effectively reduce the number of PBCH detections. In the high signal-to-noise ratio range, the number of PBCH detections is reduced from at most 4 times to 1 time, thereby greatly reducing the implementation complexity and power consumption of the terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 In a preferred embodiment of the present invention, it is a schematic flowchart of a method for blind channel detection in a Long Term Evolution (LTE) system;

[0061] Figure 2 In a preferred embodiment of the present invention, it is a schematic flowchart of step S1;

[0062] Figure 3 In a preferred embodiment of the present invention, it is a schematic flowchart of step S12;

[0063] Figure 4 In a preferred embodiment of the present invention, it is a schematic flowchart of the overall process of candidate detection and sorting of the number of antenna ports;

[0064] Figure 5 In a preferred embodiment of the present invention, it is a schematic flowchart of step S2;

[0065] Figure 6 In a preferred embodiment of the present invention, it is a schematic flowchart of determining the scrambling code detection and sorting during LLR merging between wireless frames within 40 ms in step S3;

[0066] Figure 7 In a preferred embodiment of the present invention, it is a schematic flowchart of determining the scrambling code detection and sorting during LLR merging between wireless frames within 40 ms in another case of step S3;

[0067] Figure 8 In a preferred embodiment of the present invention, it is a schematic flowchart of the physical broadcast channel detection in step S3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0068] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0069] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0070] Next, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments, but it is not a limitation of the present invention.

[0071] See Figure 1 , in a preferred embodiment of the present invention, in view of the above problems existing in the prior art, a method for blind channel detection in a Long Term Evolution system is provided, including:

[0072] Step S1: Obtain the grouping metric values corresponding to the antenna port number candidates, and determine the detection sorting of multiple antenna port number candidates according to the grouping metric values.

[0073] Step S2: For each radio frame, perform scrambling and descrambling processing on the log-likelihood ratio (LLR) obtained by demodulating the physical broadcast channel in the radio frame in sequence according to a plurality of preset scrambling candidates, calculate the correlation values of the descrambled log-likelihood ratios of each scrambling candidate, and then determine the scrambling detection sorting of multiple scrambling candidates of the current radio frame according to the correlation value sorting.

[0074] Step S3: According to the scrambling detection sorting of all radio frames within one transmission period of the physical broadcast channel, merge the descrambled log-likelihood ratios corresponding to the scrambling candidates with non-zero correlation values, and use the merged log-likelihood ratios to perform detection of the physical broadcast channel on the antenna port.

[0075] Specifically, aiming at the problem that the blind detection complexity is still very high when the working signal-to-noise ratio of the PBCH specified in the LTE standard is in the low signal-to-noise ratio range in the prior art, the blind detection method of the present invention is divided into three steps: The first step is to detect and sort the antenna port number candidates; the second step is to detect and sort the scrambling candidates corresponding to each radio frame within one transmission period (i.e., 4 radio frames, a total of 40 ms); the third step is the scrambling detection sorting during the LLR merging between radio frames within 40 ms.

[0076] In order to reduce power consumption, by detecting the antenna port number candidates and scrambling candidates according to the priority, even in the low signal-to-noise ratio range, the number of PBCH detections can be effectively reduced, and in the high signal-to-noise ratio range, the number of PBCH detections can be reduced from at most 4 times to 1 time, thereby greatly reducing the complexity and power consumption of the terminal implementation.

[0077] Further, the antenna port number candidates include three configurations: the antenna port number is 1, the antenna port number is 2, and the antenna port number is 4.

[0078] In the first step, the detection sorting of the antenna port number candidates, that is, sorting the detection priorities of 3 antenna port number candidates according to certain rules. Among them, the antenna port number detection priority means that the antenna port number with a higher priority is detected before the antenna port number with a lower priority. If the PBCH decoding is successful, the remaining antenna port number candidates do not need to be detected; if the PBCH decoding fails, select the one with a higher priority from the remaining antenna port number candidates for detection first.

[0079] As a preferred embodiment, among them, as Figure 2 shown, step S1 includes:

[0080] Step S11: Group the metric values corresponding to the antenna ports according to the antenna port number candidates, so as to obtain the grouped metric values corresponding to each antenna port number candidate.

[0081] Step S12: Compare each grouped metric value with the decision threshold to determine the detection sorting of multiple antenna port number candidates.

[0082] Specifically, in this embodiment, first, estimate the metric values of each antenna port and fixedly divide them into three groups according to the antenna port number candidates. Among them, the antenna port number candidates are 1, 2, or 4. The grouped metric values corresponding to each antenna port number candidate include different antenna ports, that is, the grouped metric values include the first grouped metric value corresponding to the first antenna port, the second grouped metric value corresponding to the second antenna port, and the third grouped metric value corresponding to the third and fourth antenna ports.

[0083] Furthermore, the metric value is preferably defined as power, and the three groups of metric values are respectively expressed as:

[0084]

[0085]

[0086] Among them, P0 represents the first grouped metric value; P1 represents the second grouped metric value; P2 represents the third grouped metric value; represents the received signal corresponding to the i-th CRS of the j-th receiving antenna of antenna port p, p = 0, 1, 2, 3, that is respectively represent the received signals corresponding to the first antenna port, the second antenna port, the third antenna port, and the fourth antenna port of the i-th CRS of the j-th receiving antenna; i = 1,..., 12; j = 1,..., N rx , N rx represents the number of receiving antennas.

[0087] More specifically, at the same time, use the Secondary Synchronization Signal (SSS) to obtain the noise power σ 2 , and its calculation formula is:

[0088]

[0089] Among them, set represents the set of SSSs participating in the calculation; N set represents the number of elements in the set; S SSS,k represents the k-th SSS transmission signal in the set; R SSS,k represents the k-th SSS received signal in the set; H flt,k represents the channel estimation value corresponding to the k-th SSS in the set.

[0090] As a preferred embodiment, wherein the determination method of the judgment threshold P TH is as follows:

[0091] P TH = max(ασ 2 , βP0)

[0092] wherein, α represents the amplification factor of the noise power σ 2 , α≥1; β represents the scaling factor of the first group metric value P0 corresponding to the first antenna port, β≥0; P TH represents the judgment threshold.

[0093] More specifically, the above amplification factor α and scaling factor β can be obtained through simulation.

[0094] As a preferred embodiment, as shown in Figure 3 , step S12 includes:

[0095] Step S121, determining whether the third group metric value is not less than the decision threshold:

[0096] If so, set the detection priority of the antenna port number candidate corresponding to the third group metric value as 4 to the highest, and determine the detection priorities of the antenna port number candidates as 1 and the antenna port number candidate as 2 according to the magnitudes of the first group metric value and the second group metric value, and enter step S124;

[0097] If not, enter step S122;

[0098] Step S122, determining whether the second group metric value is not less than the decision threshold:

[0099] If so, set the detection priority of the antenna port number candidate corresponding to the second group metric value as 2 to the highest, and determine the detection priorities of the antenna port number candidates as 1 and the antenna port number candidate as 4 according to the magnitudes of the first group metric value and the third group metric value, and enter step S124;

[0100] If not, enter step S123;

[0101] Step S123, determining whether the first group metric value is not less than the decision threshold:

[0102] If so, set the detection priority of the antenna port number candidate corresponding to the first group metric value as 1 to the highest, and determine the detection priorities of the antenna port number candidates as 2 and the antenna port number candidate as 4 according to the magnitudes of the second group metric value and the third group metric value, and enter step S124;

[0103] If not, determine the detection priorities of candidate antenna port numbers 1, 2, and 4 according to the magnitudes of the first grouped metric value, the second grouped metric value, and the third grouped metric value;

[0104] Step S124: Determine the detection order according to the detection priorities of each candidate antenna port number.

[0105] Specifically, compare the three grouped metric values with the judgment threshold P TH sequentially to determine the detection priority order of candidate antenna port numbers.

[0106] First, compare the third grouped metric value P2 with the judgment threshold P TH If the third grouped metric value P2 ≥ P TH , it is considered that the probability that the candidate antenna port number configured by the base station is 4 is the largest. First, detect the candidate antenna port number 4, and then sort the other antenna port numbers according to power, and detect the one with the larger power first. That is, set the detection priority of the candidate antenna port number corresponding to the larger of the first grouped metric value P0 and the second grouped metric value P1 to be the second, and set the detection priority of the candidate antenna port number corresponding to the smaller one to be the lowest. That is:

[0107] Compare the first grouped metric value P0 and the second grouped metric value P1. If P1 ≥ P0, first detect the candidate antenna port number 2, and then detect the candidate antenna port number 1; conversely, if P1 < P0, first detect the candidate antenna port number 1, and then detect the candidate antenna port number 0.

[0108] If the third grouped metric value P2 is less than P TH , then compare the second grouped metric value P1 with the judgment threshold P TH If the second grouped metric value P1 ≥ P TH , it is considered that the probability that the candidate antenna port number configured by the base station is 2 is the largest. First, detect the candidate antenna port number 2, and sort the other antenna port numbers according to power, and detect the one with the larger power first. That is, set the detection priority of the candidate antenna port number corresponding to the larger of the first grouped metric value P0 and the third grouped metric value P2 to be the second, and set the detection priority of the candidate antenna port number corresponding to the smaller one to be the lowest. That is:

[0109] Compare the first grouped metric value P0 and the third grouped metric value P2. If P2 ≥ P0, first detect the candidate antenna port number 4, and then detect the candidate antenna port number 1; conversely, if P2 < P0, first detect the candidate antenna port number 1, and then detect the candidate antenna port number 4.

[0110] If the second grouped metric value P1 is also less than P TH, then compare the first group metric value P0 with the judgment threshold P TH If the first group metric value P0≥P TH , it is considered that the probability that the candidate number of antenna ports configured by the base station is 1 is the largest. The first detected candidate number of antenna ports is 1, and the other candidate numbers of antenna ports are sorted according to power, and the ones with larger power are detected first. That is, set the detection priority of the candidate number of antenna ports corresponding to the larger one of the second group metric value P1 and the third group metric value P2 to be the second, and set the detection priority of the candidate number of antenna ports corresponding to the smaller one to be the lowest. That is:

[0111] Compare the second group metric value P1 and the third group metric value P2. If P2≥P1, first detect the candidate number of antenna ports as 4, and then detect the candidate number of antenna ports as 2; otherwise, if P2<P1, first detect the candidate number of antenna ports as 2, and then detect the candidate number of antenna ports as 4.

[0112] Specifically, the pseudo-code form can be:

[0113] If P2≥P TH

[0114] Psort(1)=2;

[0115] % Sort 2

[0116] If P1≥P0

[0117] Psort(2)=1;

[0118] Psort(3)=0;

[0119] Else

[0120] Psort(2)=0;

[0121] Psort(3)=1

[0122] end

[0123] Elseif P1≥P TH

[0124] Psort(1)=1;

[0125] % Sort 1

[0126] If P2≥P0

[0127] Psort(2)=2;

[0128] Psort(3)=0

[0129] Else

[0130] Psort(2) = 0;

[0131] Psort(3) = 2

[0132] end

[0133] Elseif P0 ≥ P TH

[0134] Psort(1) = 0;

[0135] % Sorting 0

[0136] If P2 ≥ P1

[0137] Psort(2) = 2;

[0138] Psort(3) = 1

[0139] Else

[0140] Psort(2) = 1;

[0141] Psort(3) = 2

[0142] end

[0143] Else

[0144] % Sorting

[0145] Psort = sort([P0, P1, P2], 'descend') % Sort in descending order of power

[0146] end

[0147] Among them, the number of antenna ports of Psort(1) indicates the highest detection priority, the number of antenna ports of Psort(2) indicates the second highest detection priority, and the number of antenna ports of Psort(3) indicates the lowest detection priority. The process is as Figure 4 shown.

[0148] In the low signal-to-noise ratio range, the measurement of the correct number of antenna ports is very likely to be arranged in the front. Through the detection priority sorting, the correct number of antenna ports can be detected with fewer detection times.

[0149] The second step is to detect and sort the scrambling codes. Since LTE sends PBCH in a cycle of 4 radio frames (i.e., 40 ms), and the PBCH sent in each radio frame is identified by different scrambling codes for the lower 2 bits of SFN. In order to reduce the number of blind detections corresponding to the lower 2 bits of SFN, the detection priorities of 4 groups of scrambling codes are sorted according to a certain criterion, and the ones with higher priorities are detected for PBCH first.

[0150] PBCH detection is to perform rate matching, decode the tail-biting convolutional code and decode the CRC.

[0151] In the above second step, it is also possible to determine whether the LLR is reliable. Only the reliable LLRs are further processed, while the unreliable LLRs are not processed. It is also possible to determine whether the LLR participates in the LLR combination in the third step, which can also be used for the LLR combination of the synchronization signal and the PBCH block (SSB) in the NR system.

[0152] As a preferred embodiment, where, as Figure 5 shown, step S2 includes:

[0153] Step S21, generating a scrambling sequence, equally dividing the scrambling sequence to obtain multiple scrambling candidates;

[0154] Step S22, demodulating the physical broadcast channel in the radio frame to obtain the log-likelihood ratio;

[0155] Step S23, successively using multiple scrambling candidates to descramble the log-likelihood ratio to obtain the descrambled log-likelihood ratios corresponding to the multiple scrambling candidates;

[0156] Step S24, performing correlation calculation on the descrambled log-likelihood ratios corresponding to each scrambling candidate to obtain the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates;

[0157] Step S25, sorting the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates, and determining the scrambling detection sorting of the multiple scrambling candidates of the current radio frame according to the correlation value sorting.

[0158] Specifically, in this embodiment, first, a scrambling sequence is generated, and the scrambling sequence is evenly divided into 4 equal parts, corresponding to the scrambling candidates used when mod(SFN, 4) = 0 (t = 0), mod(SFN, 4) = 1 (t = 1), mod(SFN, 4) = 2 (t = 2), and mod(SFN, 4) = 3 (t = 3), which are represented as des t,m , and stored in the scrambling storage space DESbuffer; t = 0, 1, 2, 3; m = 0, 1,..., M - 1, where t represents the scrambling candidate index; M represents the number of log-likelihood ratios LLR, and m represents the log-likelihood ratio LLR index.

[0159] Then, at a certain number of antenna ports, the PBCH in 1 radio frame is demodulated to obtain the LLR, denoted as llr m . Among them, M = 480 LLRs are obtained by demodulating the normal cyclic prefix NCP, and M = 432 LLRs are obtained by demodulating the extended cyclic prefix ECP.

[0160] Next, the LLR is successively descrambled using 4 groups of scrambling code candidates to obtain 4 groups of descrambled log-likelihood ratios LLR, denoted as That is:

[0161]

[0162] Then, correlation calculations are performed on each group of descrambled log-likelihood ratios LLR to obtain the correlation value Cor t , that is:

[0163]

[0164] Among them, llr des represents the descrambled log-likelihood ratio, the subscript t represents the scrambling code candidate index; the subscript k represents the correlation point index, k = 0,..., N - 1, N represents the correlation length, and the subscript S t represents the correlation interval.

[0165] More specifically, the parameters S t and N can be set as:

[0166]

[0167] In the case of incorrect descrambling, there is no obvious repeated part of the PBCH in each radio frame in the LTE system; in the case of correct descrambling, there is an obvious repeated part of the PBCH in each radio frame in the LTE system. Then, a high correlation value can be obtained with a greater probability during correct descrambling. Through priority sorting, correct descrambling can be achieved with fewer detection times.

[0168] Finally, 4 groups of correlation values can be calculated corresponding to the 4 scrambling code candidates, namely Cor0, Cor1, Cor2, and Cor3. The obtained 4 groups of correlation values Cor = [Cor0, Cor1, Cor2, Cor3] are sorted in descending order to obtain the scrambling code detection sorting I of the current radio frame, that is:

[0169] I = sort(Cor, ’descend’) %

[0170] Among them, the scrambling code candidate corresponding to I(1) has the highest detection priority, and the scrambling code candidate represented by I(4) has the lowest detection priority.

[0171] The terminal sorts according to the detection priority sorting of the scrambling code detection sorting I. If the corresponding correlation value is non-zero, the corresponding scrambling code is taken for descrambling, and then PBCH detection is performed; otherwise, the PBCH detection of this antenna port is stopped.

[0172] If the corresponding maximum correlation value is 0, the LLR obtained by demodulating the PBCH in this radio frame is set to all 0, that is, it does not participate in the LLR merging in the third step.

[0173] For example, for NR SSB, 864 LLRs are obtained after detection, denoted as m = 0, 1,..., 863, and their correlation values are denoted as:

[0174]

[0175] where Cor SSB represents the correlation value after descrambling the LLRs demodulated corresponding to the SSB; llr SSB represents the log-likelihood ratio after descrambling the SSB, and the subscript m represents the index of the log-likelihood ratio LLR.

[0176] If the correlation value is 0, the PBCH detection is skipped and does not participate in the LLR merging between radio frames.

[0177] The third step is the scrambling code detection and sorting process during the LLR merging between radio frames within a 40-ms period. When the signal-to-noise ratio is low, LLR merging between radio frames is required to improve the reliability of BCH. To implement the LLR merging between radio frames, the demodulated LLRs need to be stored. The storage space for this likelihood ratio is denoted as LLRbuffer, and its first-in-first-out storage process is as follows: First, the LLRs stored in the first column are stored in the 0th column, then the LLRs stored in the second column are stored in the first column, then the LLRs stored in the third column are stored in the second column, and finally the demodulated LLRs are stored in the third column, that is:

[0178]

[0179] where the superscript buffer represents the LLRs stored in the likelihood ratio storage space LLRbuffer; the subscripts 0, 1, 2, and 3 respectively represent the 0th column, the first column, the second column, and the third column stored in the likelihood ratio storage space LLRbuffer; m = 0, 1,..., M - 1.

[0180] At this time, there are two schemes for obtaining the 4 sets of correlation values required for scrambling code sorting.

[0181] The first scheme is to perform correlation on the LLRs stored in LLRbuffer after descrambling to obtain 4 sets of correlation values. As a preferred implementation, after the scrambling code descrambling process in step S2, it further includes: storing the demodulated log-likelihood ratio in the likelihood ratio storage space LLRbuffer according to the first-in-first-out storage rule;

[0182] As Figure 6 shown, step S3 includes:

[0183] Step S301A, according to multiple scrambling code candidates, successively perform scrambling code descrambling processing on the demodulated log-likelihood ratio stored in the likelihood ratio storage space to obtain multiple scrambled and descrambled log-likelihood ratios of the scrambling code candidates;

[0184] Step S302A: Calculate the correlation values of the logarithm likelihood ratios after descrambling multiple scrambling code candidates, to obtain the correlation values of the logarithm likelihood ratios after descrambling corresponding to multiple scrambling code candidates;

[0185] Step S303A: Sort the correlation values of the logarithm likelihood ratios after descrambling corresponding to multiple scrambling code candidates, and determine the scrambling code detection sorting of all radio frames within one transmission period of the physical broadcast channel according to the sorted correlation values.

[0186] Specifically, first, assume that the current scrambling code candidate mod(SFN, 4) = 0. After descrambling, 3 groups of descrambled LLRs are obtained, namely:

[0187]

[0188] Among them, respectively represent 3 groups of descrambled LLRs.

[0189] For NCP, the correlation value calculation formula is as follows:

[0190]

[0191] For ECP, in order to calculate the correlation value, the descrambled LLRs are re-expressed as:

[0192]

[0193]

[0194] Among them, the superscript Tmp represents the descrambled LLR corresponding to ECP. Its correlation value calculation formula is as follows:

[0195]

[0196] Secondly, assume that the current scrambling code candidate mod(SFN, 4) = 1. After descrambling, 4 groups of descrambled LLRs are obtained, namely:

[0197]

[0198] For NCP, the correlation value calculation formula is as follows:

[0199]

[0200] For ECP, in order to calculate the correlation value, the descrambled LLRs are re-expressed as:

[0201]

[0202] Its correlation value calculation formula is as follows:

[0203]

[0204] Then, assume that the current scrambling code candidate mod(SFN, 4) = 2. After descrambling, 4 sets of descrambled LLRs are obtained, namely:

[0205]

[0206] For NCP, the calculation formula for its correlation value is as follows:

[0207]

[0208] For ECP, in order to calculate the correlation value, the descrambled LLRs are re-expressed as:

[0209]

[0210] The calculation formula for its correlation value is as follows:

[0211]

[0212] Finally, assume that the current scrambling code candidate mod(SFN, 4) = 3. After descrambling, 4 sets of descrambled LLRs are obtained, namely:

[0213]

[0214] For NCP, the calculation formula for its correlation value is as follows:

[0215]

[0216] For ECP, in order to calculate the correlation value, the descrambled LLRs are re-expressed as:

[0217]

[0218] The calculation formula for its correlation value is as follows:

[0219]

[0220] After obtaining 4 sets of correlation values COR = [COR0, COR1, COR2, COR3], perform a descending sort on them to obtain the scrambling code detection sort of the current radio frame, namely:

[0221] I = I1 = sort(COR, 'descend') %

[0222] The second scheme is to use the correlation values obtained in the second step, store them in a cache, which is represented as a 4-row and 4-column matrix and can be expressed as the correlation value storage space CORbuffer, and then obtain the required correlation value COR = [COR acct0 , COR acct1, COR acct2 , COR acct3 As a preferred embodiment, the calculation of the correlation value in step S2 further includes: storing the correlation values of the logarithmic likelihood ratios of the multiple scrambling code candidates after descrambling in the correlation value storage space in sequence according to the first-in-first-out storage rule;

[0223] like Figure 7 As shown, step S3 includes:

[0224] Step S301B, sorting the scrambling code candidates according to the accumulated correlation values corresponding to the scrambling code candidates in the correlation value storage space to obtain accumulated correlation value sorting;

[0225] Step S302B: Determine the scrambling code detection order of all radio frames in a transmission cycle of the physical broadcast channel according to the cumulative correlation value order.

[0226] Specifically, in this embodiment, the four correlation values Cor=[Cor0, Cor1, Cor2, Cor3] corresponding to the scrambling code candidates of the first radio frame obtained in the second step are stored in the correlation value storage space CORbuffer, and the storage process is as follows:

[0227] CORbuffer(3,t)=Cor t

[0228] Among them, t=0,1,2,3.

[0229] Then, the four correlation values corresponding to the scrambling code candidates of the second radio frame obtained in the second step are stored in the correlation value storage space CORbuffer according to the first-in-first-out rule. The storage process is as follows:

[0230] CORbuffer(l-1,t)=CORbuffer(l,t)

[0231] CORbuffer(3,t)=Cor t

[0232] Wherein, l represents a matrix element, l=1,2,3.

[0233] The 4 correlation values corresponding to the scrambling code candidates of the third and fourth radio frames are stored in the same process. The cumulative correlation value COR is obtained. acct , the accumulation process is:

[0234]

[0235] Where CORbuffer represents the correlation value cache matrix; l represents the matrix element; COR accu0 Indicates the cumulative correlation value corresponding to the first scrambling code candidate; COR accu1Indicates the cumulative correlation value corresponding to the second scrambling code candidate; COR accu2 Indicates the cumulative correlation value corresponding to the third scrambling code candidate; COR accu3 Indicates the cumulative correlation value corresponding to the fourth scrambling code candidate.

[0236] Finally, for the cumulative correlation values COR = [COR acct0 , COR acct1 , COR acct2 , COR acct3 , perform a descending sort to obtain the scrambling code detection sort I for the current radio frame, that is:

[0237] I = I2 = sort(COR, ’descend’) %

[0238] Specifically, further, the terminal, according to the sort of I, if the corresponding correlation value is non-zero, takes the corresponding LLR and scrambling code candidate from the LLRbuffer and DESbuffer for descrambling, and after merging, performs PBCH detection, otherwise stops the PBCH detection for this antenna port.

[0239] The method of the present invention can also be used when the LLRbuffer is not configured. The terminal, according to the sort of I, if the corresponding correlation value is non-zero, takes the corresponding scrambling code candidate from the DESbuffer to descramble the current LLR, and then performs PBCH detection, otherwise stops the PBCH detection for this antenna port. Therefore, the second solution has higher flexibility in use.

[0240] As a preferred embodiment, wherein, as Figure 8 shown, in step S3, the detection of the physical broadcast channel includes:

[0241] Step S31, perform rate dematching on the merged log-likelihood ratio;

[0242] Step S32, perform tail-biting deconvolution on the log-likelihood ratio after rate dematching;

[0243] Step S33, perform CRC check on the log-likelihood ratio after tail-biting deconvolution, and if the check passes, the physical broadcast channel decoding is successful.

[0244] Specifically, in this embodiment, PBCH detection includes rate dematching, tail-biting deconvolution code, and deCRC.

[0245] In PBCH transmission, rate matching is to perform operations such as repetition, puncturing, or interleaving on the encoded bits to meet specific code rates and transmission requirements. Rate dematching is that the terminal performs the opposite operations on the received signal to recover the original encoded bits.

[0246] The tail-biting convolutional code is a special convolutional code. The initial state and the end state of the encoder are the same. Generally, the last few bits of the input information are used as the values of the initial registers. In PBCH encoding, the tail-biting convolutional code is used to increase the error correction ability of the data. Decoding the tail-biting convolutional code is the process of the terminal performing convolutional decoding on the received signal. It uses the characteristics of the tail-biting convolutional code to recover the original input information.

[0247] CRC is a commonly used check code, which is used to detect possible errors in the data transmission process. In PBCH transmission, CRC is added to the end of the MIB to provide additional error detection capabilities. After the terminal decodes the PBCH, it will perform a CRC check on the decoded data to verify the correctness of the data. If the CRC check fails, it indicates that an error may have occurred during the data transmission, and the PBCH decoding fails.

[0248] The present invention sorts the detection order of the number of transmit antennas and scrambling codes, reduces the number of blind detections, and thus greatly reduces the implementation complexity and power consumption of the terminal. Especially at high signal-to-noise ratios, the number of PBCH detections can be reduced from a maximum of 4 times to 1 time, that is, only one detection is required to correctly detect the PBCH. In the low signal-to-noise ratio range, the number of PBCH detections can also be effectively reduced.

[0249] The advantages or beneficial effects of adopting the above technical solutions are as follows: The present invention sorts the detection order of the number of antenna ports and scrambling codes used during transmission, that is, first sorts the detection of the number of antenna ports, then sorts the detection of the scrambling codes corresponding to each radio frame within a period, and finally sorts the detection of the scrambling codes during the log-likelihood ratio merging between radio frames within a period, thereby reducing the number of blind detections. Even in the low signal-to-noise ratio range, the number of PBCH detections can be effectively reduced. At high signal-to-noise ratios, the number of PBCH detections is reduced from a maximum of 4 times to 1 time, thereby greatly reducing the implementation complexity and power consumption of the terminal.

[0250] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be able to realize that all the equivalent replacements and obvious changes made by using the content of this specification and the drawings should be included in the protection scope of the present invention.

Claims

1. A method for blind channel detection in a Long Term Evolution (LTE) system, characterized in that, Including: Step S1: Obtain the grouped metric values corresponding to the antenna port number candidates, and determine the detection sorting of multiple antenna port number candidates according to the grouped metric values; Step S2: For each radio frame, perform scrambling and descrambling processing on the log-likelihood ratio obtained by demodulating the physical broadcast channel in the radio frame in sequence according to a plurality of preset scrambling code candidates, calculate the correlation values of the log-likelihood ratios after descrambling for each scrambling code candidate, and then determine the scrambling detection sorting of multiple scrambling code candidates of the current radio frame according to the correlation value sorting; Step S3: According to the scrambling detection sorting of all radio frames within one transmission period of the physical broadcast channel, merge the log-likelihood ratios after descrambling of the scrambling code candidates corresponding to non-zero correlation values, and use the merged log-likelihood ratios to detect the physical broadcast channel of the antenna port.

2. The method for blind channel detection in a Long Term Evolution system according to claim 1, characterized in that, The said Step S1 includes: Step S11: Group the metric values corresponding to the antenna ports according to the antenna port number candidates to obtain the grouped metric values corresponding to each antenna port number candidate; Step S12: Compare each grouped metric value with the decision threshold to determine the detection sorting of multiple antenna port number candidates.

3. The method for blind channel detection in a Long Term Evolution system according to claim 2, wherein The antenna port number candidates are 1 or 2 or 4, and the grouped metric values include the first grouped metric value corresponding to the first antenna port, the second grouped metric value corresponding to the second antenna port, and the third grouped metric value corresponding to the third and fourth antenna ports; The said Step S12 includes: Step S121: Judge whether the third grouped metric value is not less than the decision threshold: If so, set the detection priority of the antenna port number candidate corresponding to the third grouped metric value as 4 to be the highest, and determine the detection priorities of the antenna port number candidate as 1 and the antenna port number candidate as 2 according to the magnitudes of the first grouped metric value and the second grouped metric value, and enter Step S124; If not, enter Step S122; Step S122: Judge whether the second grouped metric value is not less than the decision threshold: If so, set the detection priority of the antenna port number candidate corresponding to the second grouped metric value as 2 to be the highest, and determine the detection priorities of the antenna port number candidate as 1 and the antenna port number candidate as 4 according to the magnitudes of the first grouped metric value and the third grouped metric value, and enter Step S124; If not, enter Step S123; Step S123: Judge whether the first grouped metric value is not less than the decision threshold: If so, set the detection priority of the antenna port number candidate corresponding to the first grouped metric value as 1 to be the highest, and determine the detection priorities of the antenna port number candidate as 2 and the antenna port number candidate as 4 according to the magnitudes of the second grouped metric value and the third grouped metric value, and enter Step S124; If not, determine the detection priorities of the antenna port number candidate as 1, the antenna port number candidate as 2, and the antenna port number candidate as 4 according to the magnitudes of the first grouped metric value, the second grouped metric value, and the third grouped metric value; Step S124: Determine the detection sorting according to the detection priorities of each antenna port number candidate.

4. The method for blind channel detection in a Long Term Evolution system according to claim 3, characterized in that The method for determining the judgment threshold is as follows: P TH = max ασ 2 , βP0 where α represents the amplification factor of the noise power σ 2 , α ≥ 1; β represents the scaling factor of the first packet metric value P0 corresponding to the first antenna port, β ≥ 0; P TH represents the determination threshold.

5. The method for blind channel detection in a Long Term Evolution system according to claim 1, wherein The step S2 includes: Step S21, generating a scrambling sequence, equally dividing the scrambling sequence to obtain multiple scrambling candidates; Step S22, demodulating the physical broadcast channel in the radio frame to obtain a log-likelihood ratio; Step S23, successively using multiple scrambling candidates to descramble the log-likelihood ratio to obtain the descrambled log-likelihood ratios corresponding to the multiple scrambling candidates; Step S24, performing a correlation calculation on the descrambled log-likelihood ratios corresponding to each scrambling candidate to obtain the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates; Step S25, sorting the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates, and determining the scrambling detection sorting of the multiple scrambling candidates of the current radio frame according to the correlation value sorting.

6. The method for blind channel detection in a Long Term Evolution system according to claim 1, characterized in that The calculation method of the correlation value in the step S2 is: Among them, llr des represents the descrambled log-likelihood ratio, where the subscript t represents the scrambling candidate index; the subscript k represents the correlation point index, k = 0, ..., N-1, N represents the correlation length, and the subscript S t represents the correlation interval.

7. The method for blind channel detection in a Long Term Evolution system according to claim 1, characterized in that After the scrambling descrambling process in the step S2, it further includes: storing the demodulated log-likelihood ratio into the likelihood ratio storage space according to the first-in first-out storage rule; The step S3 includes: Step S301A, successively performing scrambling descrambling processing on the demodulated log-likelihood ratio stored in the likelihood ratio storage space according to the multiple scrambling candidates to obtain the descrambled log-likelihood ratios of the multiple scrambling candidates; Step S302A, performing a correlation value calculation on the descrambled log-likelihood ratios of the multiple scrambling candidates to obtain the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates; Step S303A, sorting the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates, and determining the scrambling detection sorting of all radio frames within one transmission period of the physical broadcast channel according to the correlation value sorting.

8. The method for blind channel detection in a Long Term Evolution system according to claim 1, wherein After the calculation of the correlation value in the step S2, it further includes: successively storing the correlation values after descrambling the log-likelihood ratios corresponding to the multiple scrambling candidates into the correlation value storage space according to the first-in first-out storage rule; The step S3 includes: Step S301B, sorting according to the cumulative correlation values corresponding to each scrambling candidate in the correlation value storage space to obtain a cumulative correlation value sorting; Step S302B, determining the scrambling detection sorting of all radio frames within one transmission period of the physical broadcast channel according to the cumulative correlation value sorting.

9. The method for blind channel detection in a Long Term Evolution system according to claim 8, wherein The cumulative correlation value is: Among them, CORbuffer represents the correlation value cache matrix; l represents the matrix element; COR accu0 represents the cumulative correlation value corresponding to the first scrambling code candidate; COR accu1 represents the cumulative correlation value corresponding to the second scrambling code candidate; COR accu2 represents the cumulative correlation value corresponding to the third scrambling code candidate; COR accu3 represents the cumulative correlation value corresponding to the fourth scrambling code candidate.

10. The method for blind channel detection in a Long Term Evolution system according to claim 1, characterized in that In the step S3, the detection of the physical broadcast channel includes: Step S31, performing rate matching demodulation on the combined log-likelihood ratio; Step S32, performing tail-biting convolution demodulation on the rate-matched log-likelihood ratio; Step S33, performing CRC check on the log-likelihood ratio after tail-biting convolution demodulation, and if the check passes, the decoding of the physical broadcast channel is successful.

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