A third-party fast PDCCH blind detection method based on polar decoding metric selection

Abstract

The application discloses a third-party fast PDCCH blind detection method based on Polar decoding metric selection, and comprises the following steps: step one, using a reordering blind detection algorithm based on channel quality feedback to select a PDCCH candidate space; step two, calculating the Polar decoding path metric DM of the candidate in the third-party PDCCH blind detection process, and excluding invalid candidates and determining the effective candidate DCI format according to the DM selection result; step three, sequentially performing C-RNTI validity verification, DCI content analysis and TBS data length matching on the effective candidate to determine the only effective DCI, and realizing target identity recognition and time-frequency resource information acquisition. Compared with the traditional PDCCH blind detection method, the method provided by the application can simultaneously reduce the PDCCH blind detection times and the DCI candidate length quantity, and significantly improves the third-party blind detection efficiency under the premise of ensuring the target capture rate.

Description

Technical Field

[0001] This invention belongs to the field of communications, and in particular relates to a third-party fast PDCCH blind detection method based on Polar decoding metric selection. Background Technology

[0002] With the unprecedented development of mobile communication technology, society has entered a construction period of "5G-enabled comprehensive development," and the explosive growth in the number of 5G mobile terminals has become an inevitable trend. The surge in the number of network users has created an urgent need for research on 5G terminal management technology. Passive terminal detection technology is a common form of terminal management technology. Passive terminal detection technology generally refers to using third-party equipment to listen to and decode the air interface signal of a terminal to obtain the target terminal's identity information or uplink / downlink time-frequency resource distribution information. Passive terminal detection equipment does not need to transmit any signals during operation; its passive listening static characteristics make it difficult for the third party to be detected by the target terminal equipment or public network base station, thus offering stronger concealment and resistance to attack, and providing significant potential for engineering applications and academic research. To compensate for the shortcomings of traditional TMSI statistical passive detection technology in application scenarios, the identification and signal monitoring of specific target terminals can be achieved through PDSCH data length matching. However, on the one hand, passive detection technology cannot obtain the uplink and downlink time-frequency resources of the target terminal in advance, which makes its third-party PDCCH blind detection process different from that of conventional communication blind detection: the maximum number of blind detections is several times that of conventional communication blind detection, greatly increasing the difficulty and complexity of blind detection. On the other hand, since the signal detection time window in passive terminal detection technology is limited, and the equipment is generally required to be portable and the hardware implementation is relatively simple, there are high requirements for the accuracy and complexity of third-party blind detection.

[0003] The detection efficiency and power consumption of blind detection in control channels have always been hot topics in physical layer research. Especially since the advent of 5G, the time requirement for blind detection in control channels has decreased from 16μs to 4μs. Research on blind detection algorithms for PDCCH in mobile communication terminal devices has significant practical implications. Furthermore, blind detection algorithms face fewer limitations in conventional communication scenarios, leading to diverse research directions and abundant research results. However, research on blind detection algorithms for third parties has been less pursued due to its numerous constraints and high research difficulty. Therefore, designing an efficient blind detection method that conforms to 5G communication protocol standards and is suitable for third-party blind detection scenarios is of great importance. Summary of the Invention

[0004] To overcome the problem of excessive complexity in third-party blind detection, this invention provides a fast third-party PDCCH blind detection method based on Polar decoding metric selection. It addresses both the PDCCH blind detection algorithm and the Polar decoding algorithm. First, it reduces the number of third-party PDCCH blind detections by dynamically adjusting the PDCCH blind detection order. Then, it eliminates invalid candidates and determines the length of valid candidate DCIs through the selection of Polar decoding metric. Finally, it determines the unique valid target DCI through a series of candidate validity verifications. This method achieves more efficient and faster third-party PDCCH blind detection while maintaining target capture rate.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A third-party fast PDCCH blind detection method based on Polar decoding metric selection includes the following specific steps:

[0007] Step 1: The third-party device obtains the current cell configuration information through listening and decoding; based on channel quality and MCS (modulation and coding scheme), it ranks the probabilities of each aggregation level that can be used by the base station-side PDCCH (physical downlink control channel), and selects PDCCH candidates of the corresponding aggregation level for blind detection in this order; the number of PDCCH candidates selected by the third party in the user-dedicated search space is... The value of i ranges from 1 to n. AL n AL To determine the number of aggregation levels, the 5G-defined User-Dedicated Search Space (USS) has 5 different aggregation levels; AL i The i-th PDCCH aggregation level has a value range of [1, 2, 4, 8, 16]. The total number of control channel particles (CCEs) contained in the current CORESET (control resource set); the starting position index of the PDCCH candidate CCE is an integer multiple of AL;

[0008] Step 2: Perform blind detection on PDCCH candidates of the same aggregation level. During the SC serial cancellation decoding process, calculate the polarization decoding path metric (DecisionMetric, DM) for each candidate based on the DCI (Downlink Control Information) length, denoted as... Where N is the length of the Polar decoding master code; K is the length of the current blind detection DCI; It is the decoded value of the i-th information bit in the decoded sequence; It is a decoding sequence The LLR of the i-th bit, where This represents the sequence of received bits from 1 to N. Represents the decoding sequence from bit 1 to bit i; u iIndicates the i-th bit of the decoding sequence;

[0009] Step 3: For each candidate in the DCI candidate decoding length K i The DMs are sorted according to the decoding length K' used for invalid candidate removal, where 1 ≤ i ≤ Y; Y is the number of DCI candidate lengths obtained by a third party, and the invalid candidate removal decoding length K' is greater than the decoding lengths of all DCI candidate lengths K. i , with K i Make effective distinctions;

[0010] Step 4: Select the validity of PDCCH candidates based on the DM ranking results; exclude PDCCH candidates that obtain the minimum DM value at K'; exclude candidates that obtain the minimum DM value at K'. i The PDCCH candidate that obtains the minimum DM value is selected as K. i The effective DCI length for this candidate;

[0011] Step 5: Based on the selection results of Step 4, perform CRC (Cyclic Redundancy Check) on the valid PDCCH candidates to obtain the current C-RNTI (Cell Radio Network Temporary Identifier) ​​candidate; determine the validity of the PDCCH candidate based on the C-RNTI validity verification: under the corresponding higher layer parameter configuration conditions, verify whether the current C-RNTI candidate value satisfies its relationship with the current PDCCH candidate CCE location index;

[0012] Step 6: Perform DCI content parsing on the PDCCH candidates that have passed the C-RNTI validity verification in Step 5. Parse the current DCI candidates according to the general DCI legal format and determine the legality of the DCI candidate content.

[0013] Step 7: Perform PDSCH (Physical Downlink Shared Channel) and TBS (Transmission Block Size) data length matching on the legitimate candidates from Step 6 to determine the unique valid DCI and achieve target identification.

[0014] Furthermore, the specific process for selecting PDCCH candidates is as follows:

[0015] Step 1.1: The third-party device obtains the target cell's BWP (partial bandwidth) configuration and its corresponding CORESET and SS (search space) configuration parameters to determine the detection timing and time-frequency range of the PDCCH signal;

[0016] Step 1.2: For the search space s associated with the control resource set p, in time slots... Above, PDCCH candidates with aggregation level L The formula for calculating the i-th CCE position index is:

[0017]

[0018] in, Indicates the start position of the PDCCH frequency domain; in the CSS (Common Search Space), That is, the starting position is the same for all UEs (User Equipment); in the USS, mod represents the modulo operation, and has the following fixed values: Y p,-1 =n RNTI ≠0, D=65537, when the value of pmod3 is 0, 1, 2, the parameter A related to p p They are 39827, 39829, and 39839 respectively; n is defined as follows: RNTI The value is C-RNTI; n CI This is a carrier indicator; the value is indicated by higher-layer parameters. The address of the PDCCH candidate, with a value of in N represents the maximum number of PDCCH candidates under aggregation level L in the search space s; CCE,p This indicates the number of CCEs in CORESETp; the value of i ranges from 0, ..., L-1, representing the 1st to Lth CCEs that make up the PDCCH, respectively.

[0019] As can be seen from formula (1), the starting position of the candidate PDCCHCCE is related to C-RNTI; the UE substitutes its own C-RNTI value into the formula during the regular blind detection process to calculate a more accurate candidate PDCCHCCE position, thereby reducing the complexity of blind detection.

[0020] However, in third-party blind testing, the C-RNTI is unknown, making it impossible to obtain a more accurate PDCCH candidate set using formula (1). Therefore, it is necessary to traverse the entire PDCCH search space. However, observing formula (1), using the information that the starting position index of the PDCCH candidate CCE must be an integer multiple of the aggregation level, the CCE with an index that is an integer multiple of AL is selected as the starting CCE of the current blind testing PDCCH candidate within the entire CORESET frequency domain. Furthermore, it is required that all constituent CCEs of the candidate are within the CORESET frequency domain resource range. In USS, the number of PDCCH candidates within the same CORESET is...

[0021]

[0022] Where, n AL The number of aggregation levels is fixed at 5 in USS; This represents the total number of CCEs contained in the current CORESET.

[0023] Step 1.3: Based on the CQI channel quality indication uploaded by the terminal and the equipment capabilities, the base station selects an appropriate aggregation level for DCI of different formats and lengths, in conjunction with the current MCS regulations. This also corresponds to the channel coding and rate matching scheme used by the signal. Therefore, the receiver can sort the probability of the PDCCH aggregation level used by the base station according to the current channel quality and MCS regulations, and blindly detect the PDCCH candidate corresponding to the aggregation level with the highest probability in this order.

[0024] Step 1.4: Perform blind testing on PDCCH of different polymerization grades separately.

[0025] Furthermore, step 5 specifically includes the following steps:

[0026] The PDCCH transmitter uses a local scrambling sequence to scramble the rate-matched data. The 5G local scrambling sequence c(n) is generated as follows:

[0027] c(n)=(x1(n+N c )+x2(n+N c ))mod2(4)

[0028] in,

[0029] x1(n+31)=(x1(n+3)+x1(n))mod2(5)

[0030] x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2(6)

[0031] In the formula, The initial value of the x2 sequence in PDCCH is calculated using the following formula:

[0032]

[0033] In the formula n ID This is equal to the value of the high-level configuration parameter "pdcch-DMRS-ScramblingID", or 0 if not configured. RNTI The value is C-RNTI only when the UE-dedicated search space is available and pdcch-DMRS-ScramblingID is configured; otherwise, it is 0.

[0034] In the third-party blind detection, the C-RNTI is unknown, therefore, it is necessary to determine the validity of the C-RNTI candidates obtained in step 5: This involves generating parameter n in the scrambling sequence. RNTI When n is 0, verify whether the relationship between the current candidate C-RNTI and the starting CCE position index of the current PDCCH candidate satisfies formula (1); RNTI If n is not 0, determineRNTI Check if it is equal to the current candidate C-RNTI; if the current candidate C-RNTI meets the condition, it is initially determined to be valid and proceeds to the next stage; otherwise, it is determined to be invalid and returns to select the next PDCCH candidate or the next n. RNTI Conduct blind inspections.

[0035] Furthermore, step 6 specifically includes the following steps:

[0036] After completing the CRC check, the A-bit information of the candidate DCI is obtained. The A-bit DCI is the final result of subtracting 24 CRC check bits from the K-bit information sequence in the first-stage decoding result. The current candidate DCI content is parsed according to the legal format configured by the higher layer and the transmission scenario to determine its validity. For example, the first bit, the IdentitiesforDCIformats field, must be 1, because it indicates the downlink PDSCH. Similarly, the validity of other fields is parsed sequentially according to the current transmission scenario. If the current candidate DCI format is determined to be valid, the next step, data length matching, is performed; otherwise, the process returns to the first stage to select the next PDCCH candidate or the next n-bit candidate. RNTI Conduct blind inspections.

[0037] Furthermore, step 7 specifically includes the following steps:

[0038] Step 7.1: Determine the PDSCH modulation order Q m Target bitrate R, Redundant version RV

[0039] Read the 5-bit Modulation and Coding Scheme field from the DCI to obtain I. MCS For DCI scrambling using C-RNTI, use I according to the high-level PDSCH-Config or SPS-Config parameter configuration. MCS The modulation order Q can be obtained by referring to Tables 5.1.3.1-1 / 2 / 3 in 3GPP TS 38.214. m 1. Target bit rate R; 2. Read the 2-bit Redundancyversion field from the DCI to obtain the redundancy version RV;

[0040] Step 7.2: Determine the number of time slots N. RE

[0041] The total number of REs (Resource Particles) allocated to PDSCH is determined based on the number of RBs in the PRB (Physical Resource Block) and the number of PRBs allocated to PDSCH; this is determined using formulas (8) and (9).

[0042]

[0043] NRE =min(156,N') RE )*n PRB (9)

[0044] Among them, N' RE The number of REs allocated to the UE within each PRB; The number of subcarriers of a PRB in the frequency domain The number of OFDM symbols allocated to the PDSCH in a time slot; The number of REs occupied by the DMRS (demodulation reference signal) in a PRB; Indicated by the high-level parameter PUSCH-ServingCellConfig::xOverhead; n PRB N represents the number of PRBs allocated to the UE. RE This is the total number of REs allocated to the UE.

[0045] Step 7.3: Obtain the intermediate number N of information bits. info

[0046] N info =N RE *R*Q m *v(10)

[0047] Step 7.4, Quantize N info Determine the Transport Block Size (TBS).

[0048] When N info ≤3824, information bit quantization intermediate number N i ' nfo for

[0049]

[0050] in, otherwise

[0051]

[0052] in, Once the intermediate quantization value is obtained, the TBS can be obtained by referring to Table 3GPPTS38.214 Table 5.1.3.2-1 or by continuing the calculation according to the general procedure.

[0053] Compared with existing technologies, the present invention, employing the above technical solution, has the following technical advantages: it can reduce the average number of blind detections in PDCCH by dynamically adjusting the blind detection order of the aggregation level, and it can determine the effective length of DCI based on the sorting selection of path metrics. This significantly improves blind detection efficiency while maintaining target acquisition accuracy, making it applicable in third-party scenarios. The present invention also considers the impact of different channel qualities, aggregation levels, and coding rates on the blind detection process and results, demonstrating stable performance and practical application value. Attached Figure Description

[0054] Figure 1 It is a framework for a third-party fast PDCCH blind detection method based on Polar decoding metric selection;

[0055] Figure 2 This is the selection process for PDCCH candidates at each aggregation level during third-party blind testing;

[0056] Figure 3 This is the workflow of passive detection technology. Detailed Implementation

[0057] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0058] like Figure 1 As shown, the third-party fast PDCCH blind detection method based on Polar decoding metric selection is divided into two stages. The first stage involves selecting and validating PDCCH candidates. First, a corresponding aggregation level blind detection order is set according to the current channel quality. PDCCH candidate signals at the corresponding aggregation level are selected sequentially according to this order. Then, the candidate signals undergo SC (serial cancellation) decoding, DM sorting, invalid candidate exclusion, and C-RNTI validity verification. The second stage performs content parsing and data length matching on the surviving candidate signals according to the DCI format determined by the DM sorting results to obtain a unique and valid target DCI and C-RNTI, thus achieving target identification and signal time-frequency resource information acquisition. Figure 1 In this context, AL stands for Aggregation Level; SCDEC for SC Decoding; DCI for Downlink Control Information; DM for DCI-based Path Metric; CRC for Cyclic Redundancy Check; RNTI for Radio Cell Temporary Identifier; and PDSCHTBS for Physical Downlink Shared Channel Transport Block Size.

[0059] The specific steps are described in detail below:

[0060] Phase 1:

[0061] Step 1: Based on channel quality and MCS specifications, the PDCCH aggregation levels used by the base station are ranked in order of probability, and PDCCH candidates are selected for blind detection in this order. The number of PDCCH candidates selected by the third party in the user-dedicated search space is... Where AL represents the PDCCH polymerization level, and n AL This represents the number of aggregation levels, which is 5 in USS. This represents the total number of CCEs contained in the current CORESET. The starting index of the candidate CCE in PDCCH is an integer multiple of AL.

[0062] The specific process for selecting PDCCH candidates is as follows:

[0063] 1. For example Figure 3 The passive detection technology workflow shows the steps whereby a third-party device obtains the target cell's BWP configuration and its corresponding CORESET and SS configuration parameters to determine the detection timing and frequency range of the PDCCH signal. Figure 3 In this context, BWP represents partial bandwidth; CORESET represents control resource set; SS represents search space; CCE represents control channel particles; and REGBundle represents physical resource particle group binding.

[0064] 2. 3GPP TS 38.213 specifies that for a search space s associated with a control resource set p, in time slots... Above, PDCCH candidates with aggregation level L The formula for calculating the i-th CCE position index is:

[0065]

[0066] in,

[0067] 1) This indicates the start position of the PDCCH frequency domain. In CSS, That is, the starting position is the same for all UEs; in the USS, And there is Y p,-1 =n RNTI ≠0, D=65537, when pmod3 has a value of 0, 1, or 2, A p They are 39827, 39829, and 39839 respectively; the agreement stipulates n RNTI The value is C-RNTI;

[0068] 2)n CI This is a carrier indicator; the value is indicated by higher-layer parameters.

[0069] 3) The address of the PDCCH candidate, with a value of in This represents the maximum number of PDCCH candidates under aggregation level L in the search space s.

[0070] 4)N CCE,p This indicates the number of CCEs in CORESETp;

[0071] 5) The value range of i is 0,…,L-1, which represent the first to Lth CCEs that make up the PDCCH.

[0072] As can be seen from formula (1), the starting position of the candidate PDCCH CCE is related to the C-RNTI. During regular blind detection, the UE can substitute its own C-RNTI value into the formula to calculate a more accurate candidate PDCCH CCE position, further reducing the complexity of blind detection. However, in third-party blind detection, the C-RNTI is unknown, and formula (1) cannot be used to obtain a more accurate set of PDCCH candidates; therefore, it is necessary to traverse the entire PDCCH search space. However, observing formula (1), we can utilize the information that the starting position index of the PDCCH candidate CCE must be an integer multiple of the aggregation level to select a CCE with an index that is an integer multiple of AL within the entire CORESET frequency domain as the starting CCE of the current blind detection PDCCH candidate. Furthermore, it requires that all constituent CCEs of the candidate are within the CORESET frequency domain resource range. In the USS, the number of PDCCH candidates within the same CORESET is...

[0073]

[0074] Where, n AL This represents the number of aggregation levels, which is 5 in USS. This represents the total number of CCEs contained in the current CORESET.

[0075] 3. Through research on the generation and transmission process of 5G physical layer control signals, it was found that the aggregation level selected by the transmitting end of the PDCCH signal is related to factors such as the length of the DCI information and the channel transmission quality. The base station selects an appropriate aggregation level for DCIs of different formats and lengths based on the CQI (Channel Quality Indication) uploaded by the terminal and the equipment capabilities, combined with the current MCS specifications. This also corresponds to the channel coding and rate matching scheme used by the signal. Therefore, the receiving end can rank the probability of the PDCCH aggregation levels used by the base station according to the current channel quality and MCS specifications, and prioritize blind testing of the PDCCH candidate corresponding to the aggregation level with the highest probability. The process for selecting PDCCH candidate signals of different aggregation levels during third-party blind testing is as follows: Figure 2 As shown.

[0076] 4. Performing blind detection separately on PDCCHs of different aggregation levels helps to distinguish the impact of their different channel coding and rate matching schemes on subsequent processes.

[0077] Step 2: Perform blind detection on PDCCH candidates of the same aggregation level, sequentially performing REGBunble deinterleaving, descrambling, rate matching, and Polar decoding operations to obtain the original information bitstream data. The Polar decoding path metric DM for each candidate based on the DCI length is calculated as follows:

[0078]

[0079] Where N is the length of the Polar decoding master code; K is the length of the current blind detection DCI; It is the decoded estimate of the i-th information bit in the decoded sequence; It is a decoding sequence LLR of the i-th bit.

[0080] The following is an explanation of this path metric:

[0081] The original SCL decoding algorithm's path metric only considers the probability of correctly decoding information bits. The metric used here introduces the DCI length K as a "penalty factor" for the decoding result, increasing the dimensionality of the path metric. Therefore, the smaller the DM value, the higher the dual accuracy of both the DCI size and content.

[0082] Step 3, for each candidate in the DCI candidate decoding length K i (1≤i≤Y) is sorted with the DM calculated under the decoding length K' used for invalid candidate removal. Here, Y is the number of DCI candidate lengths obtained from a third party, and the invalid candidate removal decoding length K' is greater than the decoding lengths of all DCI candidate lengths K. i (1≤i≤Y), and K i (1≤i≤Y) can be used to make effective distinctions.

[0083] Step 4: Select the validity of PDCCH candidates based on the DM ranking results. In third-party blind detection scenarios, the vast majority of PDCCH candidates are invalid signals. From a third-party perspective, and considering the validity of candidate signals, we will further discuss the DM metric based on DCI length mentioned earlier:

[0084] 1) Valid candidate signals

[0085] As mentioned earlier, due to the introduction of the DCI length as a criterion dimension in DM, the effective candidate signal has the highest accuracy, i.e., the minimum DM value, only under the decoding path with an information sequence length of K.

[0086] 2) Invalid candidate signals

[0087] An invalid candidate signal can be viewed as a 0 / 1 random sequence of length N. When decoding this sequence using the SC algorithm with an information sequence length of K, it can be considered as an assumption that "a subsequence of length K is transmitted on a reliable channel within a parent sequence of total length N." Therefore, the larger the value of K, the higher the transmission reliability of this N-length random sequence, and the greater the probability of accurate information sequence length and content during decoding at the receiver, resulting in a smaller DM (Discretionary Difference). Thus, the greater the difference between the decoding K value chosen for the invalid candidate signal and the true length of the valid DCI signal, the greater the DM difference, and the easier it is to distinguish between the two.

[0088] Therefore, in this step, PDCCH candidates that obtain the minimum DM value at K' are excluded; for those at K i (1≤i≤Y) PDCCH candidate selection K that obtains the minimum DM value i (1≤i≤Y) is the effective DCI length for this candidate.

[0089] Step 5: Based on the selection results in Step 4, perform CRC verification on the valid PDCCH candidates to obtain C-RNTI candidates, and verify their C-RNTI validity.

[0090] The PDCCH transmitter uses a local scrambling sequence to scramble the rate-matched data. The 5G local scrambling sequence c(n) is generated as follows:

[0091] c(n)=(x1(n+N c )+x2(n+N c ))mod2(4)

[0092] in,

[0093] x1(n+31)=(x1(n+3)+x1(n))mod2(5)

[0094] x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2(6)

[0095] In the formula, The initial value of the x2 sequence in PDCCH is calculated using the following formula:

[0096]

[0097] In the formula n ID This value equals the high-level configuration parameter pdcch-DMRS-ScramblingID; if not configured, it is 0. RNTI The value is C-RNTI only when the UE-dedicated search space is available and pdcch-DMRS-ScramblingID is configured; otherwise, it is 0.

[0098] In third-party blind detection, the C-RNTI is unknown, therefore, it is necessary to determine the validity of the C-RNTI candidates obtained in this step: This involves generating parameter n in the scrambling sequence. RNTI When n is 0, verify whether the relationship between the current candidate C-RNTI and the starting CCE position index of the current PDCCH candidate satisfies formula (1); RNTI If n is not 0, determine RNTI Check if it is equal to the current candidate C-RNTI. If the current C-RNTI candidate meets the condition, it is initially determined to be valid and proceeds to the next stage; otherwise, it is determined to be invalid and returns to select the next PDCCH candidate or the next n. RNTI Conduct blind inspection;

[0099] Phase Two:

[0100] Step 6: Perform DCI content parsing on the PDCCH candidates that have passed the C-RNTI validity verification in Step 5 to determine the legality of the DCI content.

[0101] After completing the CRC check, the A-bit information of the candidate DCI is obtained. The A-bit DCI is the final result of subtracting 24 CRC check bits from the K-bit information sequence in the first-stage decoding result. The current candidate DCI content is parsed according to the protocol specifications and the legal format configured at higher layers to determine its validity. For example, the first bit, the IdentitiesforDCIformats field, must be 1 because it indicates the downlink PDSCH. Similarly, other fields are parsed for validity. If the current candidate DCI format is deemed valid, the process proceeds to the next step of data length matching; otherwise, it returns to the first stage to select the next PDCCH candidate or the next n. RNTI Conduct blind inspections.

[0102] Step 7: Further perform PDSCHTBS data length matching on the DCI candidates with valid content from Step 6 to determine the unique valid DCI and achieve target recognition.

[0103] 1. Determine the PDSCH modulation order Q m Target bitrate R, Redundant version RV

[0104] Read the 5-bit Modulation and Coding Scheme field from the DCI to obtain I. MCS For DCI scrambling using C-RNTI, I is used according to the high-level PDSCH-Config or SPS-Config parameter configuration. MCS The modulation order Q is obtained by referring to Tables 5.1.3.1-1 / 2 / 3 of 3GPP TS38.214. mTarget bit rate R. Read the 2-bit Redundancyversion field from the DCI to obtain the redundancy version RV.

[0105] 2. Determine the number of time slots N. RE

[0106] The total number of REs allocated to PDSCH is determined based on the number of RBs in the PRB and the number of PRBs allocated to PDSCH. This is determined using formulas (8) and (9).

[0107]

[0108] N RE =min(156,N') RE )*n PRB (9)

[0109] 3. Obtain the median number N of the information bits. info

[0110] N info =N RE *R*Q m *v(10)

[0111] 4. Quantization of N info Determine TBS

[0112] When N info ≤3824, the intermediate number of information bit quantization is

[0113]

[0114] in, otherwise

[0115]

[0116] in, After obtaining the quantization intermediate value, the TBS is obtained by referring to Table 3GPPTS38.214 Table 5.1.3.2-1 or by calculation.

[0117] In the passive terminal detection scenarios described in this invention, the TBS of the PDSCH carrying the target terminal data should fluctuate within a certain range. Therefore, third-party detection equipment can filter out the unique and valid DCI format content by matching the DCI data length, ultimately capturing the target terminal's C-RNTI identity and obtaining the target's uplink and downlink time-frequency resource location information, further enabling subsequent signal monitoring.

[0118] This invention reduces the average number of blind detections in the PDCCH by dynamically adjusting the blind detection order of the aggregation level. Furthermore, it eliminates invalid candidate signals and determines valid candidate DCI formats based on path metric selection. While applicable to third-party scenarios, it significantly improves blind detection efficiency while maintaining target acquisition accuracy. This invention also considers the impact of different channel qualities, aggregation levels, and coding rates on the blind detection process and results, demonstrating stable blind detection performance and practical application value.

[0119] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any transformations or substitutions that can be conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A third-party fast PDCCH blind detection method based on Polar decoding metric selection, characterized in that, The specific steps include the following: Step 1: The third-party device obtains the current cell configuration information by listening and decoding; according to the channel quality and modulation and coding strategy (MCS), it sorts the possible aggregation levels of the physical downlink control channel (PDCCH) on the base station side, and selects the PDCCH candidates of the corresponding aggregation level for blind detection in this order. The number of PDCCH candidates selected by the third party for the user-specific search space is: The value of i ranges from 1 to n. AL n AL To determine the number of aggregation levels, the 5G-defined User-Dedicated Search Space (USS) has five different aggregation levels; AL i The i-th PDCCH aggregation level has a value range of [1, 2, 4, 8, 16]. The total number of control channel particles (CCEs) contained in the current control resource set CORESET; the starting position index of the candidate CCE in PDCCH is an integer multiple of AL; Step 2: Perform blind detection on PDCCH candidates of the same aggregation level. During the serial cancellation SC decoding process, calculate the polarization decoding path metric DM for each candidate based on the downlink control information (DCI) length, denoted as... Where N is the length of the Polar decoding master code; K is the length of the current blind detection DCI; It is the decoded value of the i-th information bit in the decoded sequence; It is a decoding sequence The LLR of the i-th bit, where This represents the sequence of received bits from 1 to N. Represents the decoding sequence from bit 1 to bit i; u i Indicates the i-th bit of the decoding sequence; Step 3: For each candidate in the DCI candidate decoding length K i The DMs are sorted according to the decoding length K' used for invalid candidate removal, where 1 ≤ i ≤ Y; Y is the number of DCI candidate lengths obtained by a third party, and the invalid candidate removal decoding length K' is greater than the decoding lengths of all DCI candidate lengths K. i , with K i Make effective distinctions; Step 4: Select the validity of PDCCH candidates based on the DM ranking results; exclude PDCCH candidates that obtain the minimum DM value at K'; exclude candidates that obtain the minimum DM value at K'. i The PDCCH candidate that obtains the minimum DM value is selected as K. i The effective DCI length for this candidate; Step 5: Based on the selection results of Step 4, perform Cyclic Redundancy Check (CRC) on the valid PDCCH candidates to obtain the current cell's Radio Network Temporary Identifier (C-RNTI) candidate; determine the validity of the PDCCH candidate based on the C-RNTI validity verification: under the corresponding higher-layer parameter configuration conditions, verify whether the current C-RNTI candidate value satisfies its relationship with the current PDCCH candidate CCE location index; Step 6: Perform DCI content parsing on the PDCCH candidates that have passed the C-RNTI validity verification in Step 5. Parse the current DCI candidates according to the general DCI legal format and determine the legality of the DCI candidate content. Step 7: Perform physical downlink shared channel (PDSCH) transport block size (TBS) data length matching on the legitimate candidates from Step 6 to determine the unique valid DCI and achieve target identification; The specific process for selecting PDCCH candidates is as follows: Step 1.1: The third-party device obtains the BWP configuration of a portion of the target cell's bandwidth and its corresponding CORESET and SS configuration parameters for the search space, and determines the detection timing and time-frequency range of the PDCCH signal; Step 1.2: For the search space s associated with the control resource set p, in time slots... Above, PDCCH candidates with aggregation level L The formula for calculating the i-th CCE position index is: in, Indicates the start position of the PDCCH frequency domain; in the public search space CSS, That is, the starting position is the same for all User Equipment (UE); in the USS, mod represents the modulo operation, and has the following fixed values: Y p,-1 =n RNTI ≠0, D=65537, when the value of pmod3 is 0, 1, 2, the parameter A related to p p They are 39827, 39829, and 39839 respectively; n is defined as follows: RNTI The value is C-RNTI; n CI This is a carrier indicator; the value is indicated by higher-layer parameters. The address of the PDCCH candidate, with values ​​of 0, ..., in N represents the maximum number of PDCCH candidates under aggregation level L in the search space s; CCE,p This indicates the number of CCEs in CORESETp; the value of i ranges from 0, ..., L-1, representing the 1st to Lth CCEs that make up the PDCCH, respectively. During the regular blind detection process, the UE substitutes its own C-RNTI value into formula (1) to calculate a more accurate candidate PDCCH CCE position, thereby reducing the complexity of blind detection; Traverse the entire PDCCH search space; utilizing the information that the starting position index of the PDCCH candidate CCE must be an integer multiple of the aggregation level, select the CCE with an index that is an integer multiple of AL as the starting CCE of the current blind detection PDCCH candidate within the entire CORESET frequency domain; and require that all constituent CCEs of the candidate are within the CORESET frequency domain resource range; in the USS, the number of PDCCH candidates within the same CORESET is... Where, n AL The number of aggregation levels is fixed at 5 in USS; This represents the total number of CCEs contained in the current CORESET. Step 1.3: Based on the CQI channel quality indication uploaded by the terminal and the equipment capabilities, the base station selects an appropriate aggregation level for DCI of different formats and lengths, in conjunction with the current MCS regulations. This also corresponds to the channel coding and rate matching scheme used by the signal. Therefore, the receiver can sort the probability of the PDCCH aggregation level used by the base station according to the current channel quality and MCS regulations, and blindly detect the PDCCH candidate corresponding to the aggregation level with the highest probability in this order. Step 1.4: Perform blind testing on PDCCHs of different polymerization levels separately; Step 7 specifically includes the following steps: Step 7.1: Determine the PDSCH modulation order Q m Target bitrate R, redundant version RV; Read the 5-bit Modulation and Coding Scheme field from the DCI to obtain I. MCS For DCI scrambling using C-RNTI, use I according to the high-level PDSCH-Config or SPS-Config parameter configuration. MCS The modulation order Q is obtained by checking the protocol separately. m Target bit rate R; Read the 2-bit Redundancy version field from the DCI to obtain the redundancy version RV; Step 7.2: Determine the number of time slots N. RE ; The total number of resource particles (REs) allocated to PDSCH is determined based on the number of RBs in the physical resource block (PRB) and the number of PRBs allocated to PDSCH; this is determined using formulas (8) and (9). N RE =min(156,N' RE )*n PRB (9) Among them, N' RE The number of REs allocated to the UE within each PRB; The number of subcarriers of a PRB in the frequency domain The number of OFDM symbols allocated to the PDSCH in a time slot; The number of REs occupied by the demodulation reference signal DMRS in a PRB; Indicated by the high-level parameter PUSCH-ServingCellConfig::xOverhead; n PRB N represents the number of PRBs allocated to the UE. RE That is, the total number of REs allocated to the UE; Step 7.3: Obtain the intermediate number N of information bits. info ; N info =N RE *R*Q m *v (10) Step 7.4, Quantize N info Determine the TBS, or Transport Block Size; When N info ≤3824, information bit quantization intermediate number N′ info for in, otherwise in, Once the intermediate quantization value is obtained, the TBS can be obtained by looking up the table or continuing the calculation according to the general process.

2. The third-party fast PDCCH blind detection method based on Polar decoding metric selection according to claim 1, characterized in that, Step 5 specifically includes the following steps: The PDCCH transmitter uses a local scrambling sequence to scramble the rate-matched data. The 5G local scrambling sequence c(n) is generated as follows: c(n)=(x1(n+N c )+x2(n+N c ))mod2 (4) in, x1(n+31)=(x1(n+3)+x1(n))mod2 (5) x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2 (6) In the formula, N c =1600, The initial value of the x2 sequence in PDCCH is calculated using the following formula: In the formula n ID This value equals the high-level configuration parameter pdcch-DMRS-ScramblingID; if not configured, it is 0. RNTI The value is C-RNTI only when the UE-dedicated search space is available and pdcch-DMRS-ScramblingID is configured; otherwise, it is 0. In the third-party blind detection, the C-RNTI is unknown, therefore, it is necessary to determine the validity of the C-RNTI candidates obtained in step 5: This involves generating parameter n in the scrambling sequence. RNTI When n is 0, verify whether the relationship between the current candidate C-RNTI and the starting CCE position index of the current PDCCH candidate satisfies formula (1); RNTI If n is not 0, determine RNTI Check if it is equal to the current candidate C-RNTI; if the current candidate C-RNTI meets the condition, it is initially determined to be valid and proceeds to the next stage; otherwise, it is determined to be invalid and returns to select the next PDCCH candidate or the next n. RNTI Conduct blind inspections.

3. The third-party fast PDCCH blind detection method based on Polar decoding metric selection according to claim 2, characterized in that, Step 6 specifically includes the following steps: After completing the CRC check, the A-bit information of the candidate DCI is obtained. The A-bit DCI is the final result of subtracting 24 CRC check bits from the K-bit information sequence in the first-stage decoding result. The current candidate DCI content is parsed according to the legal format configured by the higher layer and the transmission scenario to determine its validity. If the current candidate DCI format is found to be valid, the process proceeds to the next step of data length matching; otherwise, it returns to the first stage to select the next PDCCH candidate or the next n. RNTI Conduct blind inspections.

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