A serial rearrangement receiving method and receiver based on sparse code multiple access.

Abstract

This invention discloses a serial rearrangement receiving method and receiver based on sparse code multiple access, relating to the field of communication technology. The method includes: performing serial external iterations based on the received signals of multiple users and the initialized posterior log-likelihood ratio in order of initial confidence; updating the external iteration rounds and performing decoding verification on the output first posterior log-likelihood ratio; if there are users who have failed to decode and the external iteration rounds have not reached a threshold, then performing the next round of external iterations serially based on the received signals and the first prior log-likelihood ratios of each user who failed to decode; updating the external iteration rounds and performing decoding verification based on the output second posterior log-likelihood ratio; and outputting a decoded bit sequence when there are no users who failed to decode or the external iteration rounds have reached the threshold. This scheme helps improve the receiver performance of a sparse code multiple access system with limited complexity.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a serial rearrangement receiving method and receiver based on sparse code multiple access. Background Technology

[0002] With the rapid development of mobile communication technology, users' demands for high-speed, massive connectivity, and low-latency wireless communication are increasing. Non-orthogonal multiple access (NOMA) technology is gradually becoming a key support for future sixth-generation mobile communication systems due to its advantage of being able to carry higher throughput. Among them, sparse code multiple access (SCMA) technology allows multiple users to share limited frequency or time domain resources and has attracted widespread attention due to its high spectral efficiency, higher channel capacity, and good error correction performance.

[0003] Existing sparse code multiple access (SMA) technologies typically employ iterative detection and decoding (IDD) receivers. IDD allows detectors to utilize soft information output from decoders, effectively eliminating inter-user interference. Current IDD receivers generally rely on a combination of sparse code multiple access detectors and channel decoders to perform multiple rounds of external iterations for decoding. However, the parallel deployment of channel decoders prevents users from sharing soft information from the current iteration round. This means users with poor channel quality cannot efficiently utilize the soft information from other users' decoding outputs to improve their decoding. Furthermore, all users must perform a complete detection and decoding operation in each iteration, requiring repeated computation even for users who have successfully decoded in previous rounds. This wastes computational resources and increases system complexity and power consumption. Additionally, it prevents flexible allocation and scheduling of computational resources based on actual channel conditions, and the required number of decoders must be an integer multiple of the number of users, limiting its flexible deployment in hardware implementations. Therefore, there is an urgent need to improve the receiver performance of sparse code multiple access systems with limited complexity. Summary of the Invention

[0004] This invention provides a serial rearrangement receiving method and receiver based on sparse code multiple access, which can improve the receiver performance of sparse code multiple access systems under existing limited complexity.

[0005] The first aspect of this invention provides a serial rearrangement receiving method based on sparse code multiple access, comprising:

[0006] When receiving signals transmitted by multiple users, the system performs message passing iteration detection based on the received signals and the initial posterior log-likelihood ratio of each user to determine the first prior log-likelihood ratio. It also performs external iteration of decoding and decoding verification according to the real-time confidence level corresponding to the first prior log-likelihood ratio to determine the first posterior log-likelihood ratio of each user and update it to indicate whether the user has successfully decoded or not. The system also updates the external iteration round.

[0007] Determine if there are any users who failed to decode and whether the external iteration round has reached the external round threshold;

[0008] If the external round threshold exists but is not reached, the received signal and each first posterior log-likelihood ratio are used to perform external iterations for each unsuccessfully decoded user in sequence, determine the second posterior log-likelihood ratio of each unsuccessfully decoded user and update it to be a successful or unsuccessful decoded user, and update the external iteration round.

[0009] When it is determined that there are no users who have failed to decode or the external iteration round has reached the external round threshold, the decoded bit sequence composed of the decoded bits of each user is output.

[0010] Further, when receiving signals superimposed from multiple users, the process involves sequentially performing message passing iterative detection based on the received signals and the initial posterior log-likelihood ratio of each user to determine the first prior log-likelihood ratio, and performing external iterations of decoding and decoding verification according to the real-time confidence level corresponding to the first prior log-likelihood ratio. This process determines the first posterior log-likelihood ratio of each user and updates it to indicate whether the user has successfully decoded or not, and updates the external iteration rounds, including:

[0011] When receiving signals transmitted by multiple users superimposed, determine the initial posterior log-likelihood ratio of each user;

[0012] The message passing iterative detection is performed by using the received signal and each initial posterior log-likelihood ratio, and the first prior log-likelihood ratio of each user is output.

[0013] Calculate the real-time confidence score based on each first prior log-likelihood ratio, and sort them to determine the order of the real-time confidence scores.

[0014] According to the real-time confidence level, the user with the highest confidence level is selected as the user to be decoded;

[0015] Decode based on the first prior log-likelihood ratio of the user to be decoded, and determine the corresponding first posterior log-likelihood ratio;

[0016] The first posterior log-likelihood ratio is used for decoding verification. The user to be decoded is determined as a successful decoder or a failed decoder based on the result of whether the decoding was successful.

[0017] The message passing iterative detection is performed on the undecoded user using the current first posterior log-likelihood ratio and the updated initial posterior log-likelihood ratios to determine the new real-time confidence order.

[0018] Based on the real-time confidence level, the user with the highest confidence level is selected as the new user to be decoded, and the decoding continues until the first posterior log-likelihood ratio of each user is determined and updated to indicate whether the user has successfully decoded or failed to decode. The external iteration round is then updated.

[0019] Furthermore, message passing iterative detection is performed using each initialized posterior log-likelihood ratio, outputting the first prior log-likelihood ratio for each user, including:

[0020] Based on the initial posterior log-likelihood ratio, the message is iteratively passed to determine the prior log-likelihood ratio of any user in any current passing round.

[0021] If the current transmission round is 1, the mean absolute change is calculated by using the initial posterior log-likelihood ratio of any user and the prior log-likelihood ratio of the current transmission round.

[0022] If the current transmission round is greater than 1, the average absolute value change is calculated by comparing the prior log-likelihood ratio of any user in the previous transmission round with the prior log-likelihood ratio of the current transmission round.

[0023] When the change in the average absolute value is less than the change threshold or the current transmission round reaches the transmission round threshold, the prior log-likelihood ratio of the current transmission round is output as the first prior log-likelihood ratio for any user.

[0024] Further, the step of using the first posterior log-likelihood ratio for decoding verification, and determining whether the user to be decoded is a successful decoder or a failed decoder based on the determination result of whether decoding was successful, includes:

[0025] Decoding verification is performed using the hard decision result of the first posterior log-likelihood ratio of the user to be decoded;

[0026] If the decoding verification is passed, the user is determined to have successfully decoded, and the corresponding hard decision result is used as the decoded bit.

[0027] If there is a hard decision result indicating that the decoding verification failed, then the user is identified as having failed to decode.

[0028] Furthermore, the real-time confidence level is the average mutual information based on the prior log-likelihood ratio.

[0029] The second aspect of the present invention provides a serial rearrangement receiver based on sparse code multiple access, comprising: a sparse code multiple access detector, a channel decoder, and a decoding order controller;

[0030] A sparse code multiple access detector is used to: perform message passing iterative detection for each user or each user who failed to decode based on the received signals superimposed by multiple users and the initial posterior log-likelihood ratio or the first posterior log-likelihood ratio of each user, and determine the first prior log-likelihood ratio of each user or the second prior log-likelihood ratio of each user who failed to decode.

[0031] The channel decoder is used to: perform decoding and decoding verification based on each first prior log-likelihood ratio or each second prior log-likelihood ratio; determine the first posterior log-likelihood ratio of each user or the second posterior log-likelihood ratio of each user who failed to decode; update the user who successfully decoded or failed to decode based on the first posterior log-likelihood ratio or the second posterior log-likelihood ratio and update the external iteration round; determine whether there are any users who failed to decode and whether the external iteration round has reached the external round threshold; and when it is determined that there are no users who failed to decode or the external iteration round has reached the external round threshold, output the decoded bit sequence composed of the decoded bits of each user.

[0032] The decoding order controller is used to: determine the real-time confidence order by using the real-time confidence of each first prior log-likelihood ratio, or if there are users who have failed to decode and the external iteration round has not reached the external round threshold, determine the real-time confidence order by using the real-time confidence of each user who has failed to decode by using the second prior log-likelihood ratio, and control the sparse code multiple access detector and channel decoder to perform external iterations of message passing iteration detection, decoding and decoding verification in sequence according to the real-time confidence order.

[0033] The third aspect of the present invention provides a sparse code multiple access system, comprising: a transmitter and a serial rearrangement receiver based on sparse code multiple access as described in the second aspect of the present invention;

[0034] A transmitter is used to encode and map the bit sequences of information from multiple users, then transmit them to a receiver.

[0035] A serial rearrangement receiver based on sparse code multiple access is used to receive the received signal transmitted by the transmitter and decode it to output a decoded bit sequence.

[0036] A fourth aspect of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the serial rearrangement reception method based on sparse code multiple access as described in any of the first aspects of the present invention.

[0037] The fifth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the serial rearrangement reception method based on sparse code multiple access as described in any of the first aspects of the present invention.

[0038] The sixth aspect of the present invention provides a computer program product, comprising a computer program / instruction, wherein when the computer program / instruction is executed by a processor, it implements the serial rearrangement reception method based on sparse code multiple access as described in any of the first aspects of the present invention.

[0039] As can be seen from the above technical solutions, the present invention has the following advantages:

[0040] The above-described scheme of the present invention provides a serial rearrangement reception method based on sparse code multiple access, comprising: when receiving received signals superimposed from multiple users, performing message passing iterative detection based on the received signals and the initial posterior log-likelihood ratio of each user to determine a first prior log-likelihood ratio, and performing external iteration of decoding and decoding verification according to the real-time confidence order corresponding to the first prior log-likelihood ratio, determining the first posterior log-likelihood ratio of each user and updating it to a successfully decoded user or an unsuccessfully decoded user, and updating the external iteration round; determining whether there are unsuccessfully decoded users and whether the external iteration round has reached an external round threshold; if there are unsuccessfully decoded users and the external round threshold has not been reached, then performing external iteration of each unsuccessfully decoded user using the received signals and each first posterior log-likelihood ratio to determine the second posterior log-likelihood ratio of each unsuccessfully decoded user and updating it to a successfully decoded user or an unsuccessfully decoded user, and updating the external iteration round; when it is determined that there are no unsuccessfully decoded users or the external iteration round has reached the external round threshold, outputting a decoded bit sequence composed of the decoded bits of each user. Based on the above scheme, a serial decoding structure with serial external iterations is adopted. At the same time, the decoding timing of users is dynamically rearranged in each round of external iteration by the confidence order, so that users who perform decoding later benefit from the latest soft information output of users who have performed decoding. In addition, since users who fail to decode are dynamically determined to proceed to the next round of iteration in each round of external iteration, this not only saves computing resources, but also allows the number of decoding attempts to be set to any integer according to hardware conditions. Overall, a more flexible trade-off between performance and complexity is achieved, which helps to improve the receiver performance of the sparse code multiple access system with limited complexity. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 The flowchart illustrates the steps of a serial rearrangement receiving method based on sparse code multiple access provided in Embodiment 1 of the present invention.

[0043] Figure 2 This is a block diagram of a sparse code multiple access system for an IDD receiver provided in Embodiment 1 of the present invention;

[0044] Figure 3 This is an example of the decoding order of the IDD receiver and R-SDD receiver provided in Embodiment 1 of the present invention;

[0045] Figure 4 This is a schematic diagram comparing the computational complexity of a single codeword between an R-SDD receiver and an IDD receiver provided in Embodiment 1 of the present invention.

[0046] Figure 5 This is a schematic diagram comparing the BER curves of the R-SDD receiver and the IDD receiver provided in Embodiment 1 of the present invention. Figure 1 ;

[0047] Figure 6 This is a schematic diagram comparing the BER curves of the R-SDD receiver and the IDD receiver provided in Embodiment 1 of the present invention. Figure 2 ;

[0048] Figure 7 This is a schematic diagram of a serial rearrangement receiver based on sparse code multiple access provided in Embodiment 2 of the present invention;

[0049] Figure 8 This is a schematic diagram of a sparse code multiple access system provided in Embodiment 3 of the present invention. Detailed Implementation

[0050] This invention provides a serial rearrangement receiving method and receiver based on sparse code multiple access, which solves the technical problem of improving the receiver performance of sparse code multiple access systems under existing limited complexity.

[0051] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0052] Please see Figure 1This invention provides a serial rearrangement receiving method (R-SDD) based on sparse code multiple access (SMILE). It should be noted that this embodiment is applied to a sparse code multiple access system, which typically includes a transmitter and a receiver. In the transmitter, the preferred channel coding scheme is P-LDPC code, and each user... Information bit sequence Encoded into codewords by the channel encoder ,in, Index for users , Total number of users For information bit length, For users The One information bit, For transpose, The length of the codeword. For users The Each encoded bit, then each coded bits Divided into a group The modulation order is given, and the size is determined according to the constellation diagram. constellation chart Mapped to a sparse code multiple access encoder dimensional modulation symbol sequence ,in, Each dimension corresponds to a specific resource. Due to the sparsity of sparse code multiple access systems... Most dimensions are zero. Ultimately, the modulated symbol sequences of all users are summed and transmitted through the channel to the receiver. The received signal acquired by the receiver is... in In order to receive signals, For users The channel fading vector, This is channel noise; the receiver receives... Then, the information bits are recovered according to the following method steps in this embodiment. In specific implementation, the method includes:

[0053] Step 101: When receiving signals transmitted by multiple users, the message passing iterative detection is performed serially based on the received signals and the initial posterior log-likelihood ratio of each user to determine the first prior log-likelihood ratio. Then, the external iteration of decoding and decoding verification is performed according to the real-time confidence level corresponding to the first prior log-likelihood ratio to determine the first posterior log-likelihood ratio of each user and update it to indicate whether the user has successfully decoded or not. The external iteration round is also updated.

[0054] Received signal refers to the corresponding signal collected at the receiving end after the user transmits a signal at the sending end.

[0055] Log-likelihood ratios (LLRs) are logarithmic measures of the relative probability of a bit being 0 or 1; they are a type of soft information. The posterior log-likelihood ratio is the log-likelihood ratio output through decoding iterations. The prior log-likelihood ratio is the log-likelihood ratio output through message-passing iteration detection. It's understandable that the prior and posterior log-likelihood ratios obtained in any round of external iterations can be distinguished using terms like "first," "second," etc.

[0056] The initial posterior log-likelihood ratio refers to the preset posterior log-likelihood ratio assigned because, in the first round of external iteration, the message passing iterative detection is performed before the decoding, and the corresponding posterior log-likelihood ratio is not obtained from the decoding during the message passing iterative detection process.

[0057] Real-time confidence refers to the confidence score calculated during external iterations, used to evaluate the priority of user decoding. Real-time confidence order refers to the sequence of multiple real-time confidence scores.

[0058] A user who has successfully decoded the code is one who has completed the entire decoding process. Conversely, a user who has not successfully decoded the code is one who has not yet completed the entire decoding process.

[0059] External iteration rounds refer to the cumulative number of times an external iteration round is completed. Each external iteration round includes a message passing iteration check, decoding, and decoding verification for all users currently undergoing the external iteration.

[0060] In one specific embodiment of this example, step 101 includes the following sub-steps:

[0061] S11. When receiving signals superimposed from multiple users, determine the initial posterior log-likelihood ratio for each user.

[0062] S12. Use the received signal and each initial posterior log-likelihood ratio to perform message passing iterative detection, and output the first prior log-likelihood ratio of each user.

[0063] S13. Calculate the real-time confidence score based on each first prior log-likelihood ratio, and sort them to determine the order of the real-time confidence scores.

[0064] S14. Select the user with the highest confidence level as the user to be decoded according to the real-time confidence level order;

[0065] S15. Decode based on the first prior log-likelihood ratio of the user to be decoded, and determine the corresponding first posterior log-likelihood ratio.

[0066] S16. Use the first posterior log-likelihood ratio for decoding verification, and determine whether the user to be decoded is a successful decoder or a failed decoder based on the result of the decoding success.

[0067] S17. Using the current first posterior log-likelihood ratio to correspond to each updated initial posterior log-likelihood ratio, perform message passing iterative detection on the undecoded user to determine the new real-time confidence order.

[0068] S18. According to the real-time confidence level, select the user with the highest confidence level as the new user to be decoded, until the first posterior log-likelihood ratio of each user is determined and updated as a successful decoder or unsuccessful decoder, and update the external iteration round.

[0069] Users to be decoded refer to those who will be decoded in the current external iteration.

[0070] Undecoded users refer to users who have not yet been decoded in the current round of external iterations.

[0071] It should be noted that when receiving signals transmitted by multiple users superimposed, this embodiment uses an external iteration method to obtain the decoding result of each user. Each round of external iteration is set with a corresponding number of message transmission iteration detection, decoding and decoding verification based on the number of users that need to undergo external iteration.

[0072] Different from Figure 2 The traditional IDD receiver processing architecture shown employs an independent parallel decoding method for each user. This embodiment uses a serial decoding structure. Within any external iteration round, message passing iteration detection-decoding between users is executed serially. This allows users who decode later to utilize the posterior log-likelihood ratio obtained after decoding by previous users for message passing iteration detection. For example, after the first user decodes and obtains the first posterior log-likelihood ratio, the posterior log-likelihood ratio used by the second user for message passing iteration detection is the first posterior log-likelihood ratio of the first user and the initial posterior log-likelihood ratios of other users besides the first user. At the same time, users with higher confidence are processed first, thereby determining the first prior log-likelihood ratio and the first posterior log-likelihood ratio of each user. Based on the decoding verification result of the first posterior log-likelihood ratio, users are divided into successful decoding users or unsuccessful decoding users, and the external iteration round is updated to record.

[0073] In practical implementation, message passing iterative detection refers to iterative detection based on the message passing algorithm (MPA), with the received signal as its input. and The output is Each message passing iteration includes the following checks: The next MPA iteration This represents the total number of inner iterations. Before starting the MPA inner iterations, first... ( Defined as the first In the next iteration of message passing, from the first The user node sends to the first Initialize the mutual information (transmitted by each resource node):

[0074]

[0075] In the formula, For users The posterior log-likelihood ratio, For users The One encoded bit, For users The The posterior log-likelihood ratio corresponding to each encoded bit; it can be understood that in the first round of external iteration, since message passing iteration detection precedes decoding, there is no external information provided by decoding at this time, hence the posterior log-likelihood ratio is... Initialize to 0, Initialized to After initialization is complete, begin executing the message passing iteration, starting with the first iteration. Taking the intra-message iteration as an example, each intra-MPA iteration includes the following three steps:

[0076] 1) Traverse all and Calculate the combinations respectively. Each resource node The mutual information transmitted between user nodes; for the first user node The resource node sends to the first The mutual information transmitted by each user node can be calculated using the following formula:

[0077]

[0078] In the formula, Index for users , For users The modulation symbol sequence, To pass round index , Index for users , For users The modulation symbol sequence, Indexing resource nodes , For the first Each resource node carries a set of users. For the first Remove users from the user set supported by each resource node Subset after, For noise variance, For the first The received signal of each resource node For the first The user to the Channel fading vectors of each resource node For the first The user in the first Modulation symbols on each resource node For the first In the next iteration of message passing, from the first The user node sends to the first The mutual information transmitted between resource nodes For the first In the next iteration of message passing The resource node sends to the first Mutual information transmitted between user nodes;

[0079] 2) Traverse all and Calculate the combinations respectively. Each user node to Mutual information transmitted between resource nodes:

[0080]

[0081] In the formula, For the first In the next iteration of message passing, from the first The user node sends to the first The mutual information transmitted between resource nodes For the size of the constellation chart, Indexing resource nodes , For users The set of resource nodes used For users Remove resource nodes from the set of resource nodes used a subset of For the first In the next iteration of message passing The resource node sends to the first Mutual information transmitted between user nodes;

[0082] 3) Calculate the posterior probability of each modulation symbol and the prior log-likelihood ratio:

[0083]

[0084]

[0085] In the formula, For users The modulation symbol sequence, For posterior probability, For the size of the constellation chart, For users modulation symbols, For the first In the next iteration of message passing, the user The prior log-likelihood ratio, For the first One information bit, For users The modulation symbol corresponding to an information bit of 0 in the constellation diagram. For users The modulation symbol corresponding to an information bit of 1 in the constellation diagram;

[0086] Complete the user process by following the three steps described above. of After each MPA iteration, the result of the last MPA iteration will be used as the user's... In this round of external iteration, the prior log-likelihood ratio of the message passing iteration detection output is completed. .

[0087] In a more specific embodiment of this example, sub-step S12 includes:

[0088] S121. Based on each initial posterior log-likelihood ratio, perform iterative message transmission to determine the prior log-likelihood ratio of any user in any current transmission round.

[0089] S122. If the current transmission round is 1, the mean absolute value change is calculated by using the initial posterior log-likelihood ratio of any user and the prior log-likelihood ratio of the current transmission round.

[0090] S123. If the current transmission round is greater than 1, the average absolute value change is calculated by comparing the prior log-likelihood ratio of any user in the previous transmission round with the prior log-likelihood ratio of the current transmission round.

[0091] S124. When the change in the average absolute value is less than the change threshold or the current transmission round reaches the transmission round threshold, the prior log-likelihood ratio of the current transmission round is output as the first prior log-likelihood ratio for any user.

[0092] It should be noted that, to further reduce complexity, this embodiment also introduces an intelligent early stopping mechanism for message passing iteration detection. Specifically, in each MPA iteration, the average absolute value change of the LLR value before and after is calculated. When the average absolute value change is lower than a set threshold, it indicates that the information has converged, and the MPA iteration is terminated, directly using the current transmission round. As output, to avoid subsequent invalid calculations; among them, the change in average absolute value. The calculation process includes:

[0093]

[0094] Understandably, this mechanism takes advantage of the fact that message-passing iterative detection has completed most of the effective information exchange in the first few iterations; after testing, setting the change threshold to 30 can effectively reduce the complexity of the detector without significantly affecting performance.

[0095] In practical implementation, this embodiment uses belief propagation (BP) decoding for the P-LDPC code, with the input being... The output is The decoding process also includes The specific calculation process within each round of backpropagation iterations includes:

[0096] 1) Calculation Likelihood information :

[0097]

[0098] 2) Calculation Likelihood information :

[0099]

[0100] 3) Calculation Posterior likelihood information :

[0101]

[0102] After the inner iteration of BP is completed, the final output is given. ;

[0103] in, For the verification node index , For the first One verification node, Indexing variable nodes , For the first 1 variable node For from the first The verification node to the first Log-likelihood ratio of each variable node Indexing variable nodes , In order to be with the first The checkpoint is associated with the first one, in addition to the second one. The set of variable nodes outside of the variable nodes. For the first The variable node to the first The log-likelihood ratio of each verification node It is the hyperbolic tangent function. For the first The variable node to the first The log-likelihood ratio of each verification node For the verification node index , For the first The variable node is associated with the first variable node, in addition to the first variable node. The set of verification nodes outside of the existing verification nodes. For from the first The verification node to the first Log-likelihood ratio of each variable node For users The prior log-likelihood ratio.

[0104] In a more specific embodiment of this example, sub-step S16 includes:

[0105] S161. Use the hard decision result of the first posterior log-likelihood ratio of the user to be decoded for decoding verification;

[0106] S162. If the decoding verification is passed, the user is determined to be a successful decoder, and the corresponding hard decision result is used as the decoded bit.

[0107] S163. If there is a hard decision result that fails the decoding verification, the corresponding user is identified as having failed the decoding.

[0108] It should be noted that the decoding check is a check to determine whether the decoding has been successful, and this can be set according to the specific encoding situation; taking P-LDPC (Prototype Low-Density Parity-Check) code as an example, its corresponding decoding check can use parity checking, one... P-LDPC codes contain A parity check equation, The length of the codeword. Let LLR be the length of the information bits. If the LLR obtained by a user after decoding passes all parity checks (i.e., the hard decision result of the LLR satisfies all parity check equations), the user is considered to have successfully decoded. This is used to distinguish between successful decoding users and those who have successfully decoded. The hard decision result of a successful decoding user is then determined as the decoded bits.

[0109] In one specific implementation of this embodiment, the real-time confidence level is the average mutual information based on the prior log-likelihood ratio.

[0110] It should be noted that this embodiment uses Average Mutual Information (AMI) as the criterion for evaluating the confidence level of each user, and its calculation formula is as follows:

[0111]

[0112]

[0113] in, Indicates the first Average mutual information per user Represents the mathematical expectation function, This is a function that converts the log-likelihood ratio into mutual information.

[0114] Step 102: Determine if there are any users who have failed to decode and whether the external iteration round has reached the external round threshold.

[0115] It should be noted that for each round of external iteration, the external iteration stopping condition is set when all users have successfully decoded (i.e., the verification constraint is met), or when the set external round threshold is reached (such as the maximum number of external iterations, which is usually 5 to 10 times).

[0116] Step 103: If the external round threshold exists but has not been reached, the received signal and each first posterior log-likelihood ratio are used to perform external iterations for each unsuccessfully decoded user in sequence, determine the second posterior log-likelihood ratio of each unsuccessfully decoded user and update it to either a successfully decoded user or an unsuccessfully decoded user, and update the external iteration round.

[0117] It should be noted that if there are users who fail to decode and the external iteration rounds have not reached the external round threshold, it means that external iterations need to continue. In this case, users who successfully decode will no longer participate in subsequent external iterations to save computing resources. Therefore, the confidence level of each user who failed to decode is reassessed to determine a new real-time confidence level order for decoding. In specific implementation, the serial decoding and dynamic decoding order are rearranged according to a similar process to step 101, including the following sub-steps:

[0118] S21. Based on the received signal and each first posterior log-likelihood ratio, perform message passing iterative detection on the undecoded users and output the second prior log-likelihood ratio of each undecoded user.

[0119] S22. Use the real-time confidence levels of each second prior log-likelihood ratio to sort and determine the order of real-time confidence levels;

[0120] S23. Select the user with the highest confidence level as the user to be decoded according to the real-time confidence level order;

[0121] S24. Decode based on the second prior log-likelihood ratio of the user to be decoded, and generate the corresponding second posterior log-likelihood ratio;

[0122] S25. Use the second posterior log-likelihood ratio for decoding verification, and determine whether the user to be decoded is a new successful decoding user or a new unsuccessful decoding user based on the result of the decoding success determination.

[0123] S26. Perform message passing iterative detection on the undecoded user by taking the current second posterior log-likelihood ratio and corresponding to each updated first posterior log-likelihood ratio, and determine the new real-time confidence order.

[0124] S27. According to the real-time confidence order, select the user with the highest confidence as the new user to be decoded, until the second posterior log-likelihood ratio of each user who failed to decode in the previous external iteration round is determined and updated to the user who successfully decoded or failed to decode, and update the external iteration round.

[0125] Step 104: When it is determined that there are no users who have failed to decode or the external iteration round has reached the external round threshold, output the decoded bit sequence composed of the decoded bits of each user.

[0126] It should be noted that if the external iteration stopping condition is met, the decoded bits of each user will be combined into a decoded bit sequence. As the decoding result output, if the external iteration stopping condition is not met, the real-time confidence of each unsuccessful decoding user is calculated by using the second posterior log-likelihood ratio of the received signal and each unsuccessful decoding user according to the similar process in step 103, the real-time confidence order is determined, and the external iteration continues according to the real-time confidence order until it is determined that there are no unsuccessful decoding users or the external iteration round reaches the external round threshold, and then the decoding result is output.

[0127] To better illustrate the technical effects of this embodiment, refer to... Figures 3 to 6 The solution of this embodiment is applied to a receiver and compared with a traditional IDD receiver:

[0128] 1) To more intuitively demonstrate the dynamic reordering mechanism of the decoding sequence, in Figure 3 The decoding order of the traditional IDD receiver and the proposed R-SDD receiver is compared. In this example, user 3 has the lowest confidence and is the performance bottleneck of the whole system, while users 5 and 6 have the highest confidence. In the traditional IDD receiver, the decoding of each user is performed independently and in parallel. The R-SDD receiver always places user 3 last for decoding, so that it can fully benefit from the external information provided by other users, thereby speeding up the system convergence.

[0129] 2) In Figure 4 The computational complexity of a single codeword of the R-SDD receiver proposed in this embodiment is compared with that of a traditional IDD receiver. The channel coding scheme uniformly uses a (3, 6) regular primitive graph code with a code length of 2400. Figure 4 (a) represents the complexity of the addition operation. Figure 4 (b) represents the tanh operation complexity. For a fair comparison, both receivers are equipped with an intelligent early stop mechanism. This indicates the maximum number of decoders allowed by the system; it can be seen that, compared with the traditional IDD receiver, the R-SDD receiver proposed in this embodiment has lower computational complexity;

[0130] 3) To verify the effectiveness of the proposed R-SDD receiver, bit error rate (BER) performance simulations were performed in a 6-user, 4-resource sparse code multiple access system. All receivers used a MU-2 original pattern code with a code rate of 1 / 2 and a code length of 2400, and employed the BP algorithm for decoding. The maximum number of BP iterations was 100, and simulations were conducted based on an AWGN channel. The BER simulation results are as follows: Figures 5 to 6 As shown: Figure 5 Comparison of the same Below, the performance of the proposed R-SDD receiver compared to the traditional IDD receiver shows that the R-SDD receiver brings considerable performance gains. It is important to note that this performance gain is not achieved at the expense of complexity. Figure 6 Different settings are provided in the middle. The number of decoders in a traditional IDD receiver must be set to an integer multiple of the number of users, while the number of decoders in an R-SDD receiver can be specified arbitrarily, demonstrating the flexibility of the R-SDD receiver.

[0131] In summary, compared with existing IDD receivers, the R-SDD receiver has better performance, lower computational complexity, and more flexible hardware deployment.

[0132] In this embodiment of the invention, a serial decoding structure with sequential external iterations is adopted. Simultaneously, the decoding timing of users is dynamically adjusted in each round of external iteration based on confidence level, placing the user with the lowest current confidence level last for processing, allowing them to benefit from the latest soft information output of other users. Furthermore, since users who fail to decode are dynamically determined for the next round of external iteration in each round, this not only saves computational resources but also allows the number of decoding attempts to be set to any integer based on hardware conditions. Overall, higher mutual information propagation efficiency leads to a lower bit error rate and lower computational complexity, achieving a more flexible trade-off between performance and complexity.

[0133] Please see Figure 7 The second embodiment of the present invention provides a serial rearrangement receiver based on sparse code multiple access, comprising: a sparse code multiple access detector, a channel decoder, and a decoding order controller;

[0134] A sparse code multiple access detector is used to: perform message passing iterative detection for each user or each user who failed to decode based on the received signals superimposed by multiple users and the initial posterior log-likelihood ratio or the first posterior log-likelihood ratio of each user, and determine the first prior log-likelihood ratio of each user or the second prior log-likelihood ratio of each user who failed to decode.

[0135] The channel decoder is used to: perform decoding and decoding verification based on each first prior log-likelihood ratio or each second prior log-likelihood ratio; determine the first posterior log-likelihood ratio of each user or the second posterior log-likelihood ratio of each user who failed to decode; update the user who successfully decoded or failed to decode based on the first posterior log-likelihood ratio or the second posterior log-likelihood ratio and update the external iteration round; determine whether there are any users who failed to decode and whether the external iteration round has reached the external round threshold; and when it is determined that there are no users who failed to decode or the external iteration round has reached the external round threshold, output the decoded bit sequence composed of the decoded bits of each user.

[0136] The decoding order controller is used to: determine the real-time confidence order by using the real-time confidence of each first prior log-likelihood ratio, or if there are users who have failed to decode and the external iteration round has not reached the external round threshold, determine the real-time confidence order by using the real-time confidence of each user who has failed to decode by using the second prior log-likelihood ratio, and control the sparse code multiple access detector and channel decoder to perform external iterations of message passing iteration detection, decoding and decoding verification in sequence according to the real-time confidence order.

[0137] It should be noted that, in this embodiment, under the control of the decoding sequence controller according to the confidence order of the corresponding processes, message passing iteration detection is performed by a sparse code multiple access detector. The sparse code multiple access detector can be a sparse code multiple access detector based on a message passing algorithm (MPA). Decoding, decoding verification, external iteration stop determination, and output of decoded bits are performed by a channel decoder. The channel decoder can be a belief propagation (BP) decoder.

[0138] Each round of external iteration is... A sparse code multiple access detector and It consists of a channel decoder, in which This indicates the number of users who have not yet successfully decoded the code in the initial first round of external iterations. , For the total number of users, and in subsequent external iterations ;

[0139] Within each external iteration, the channel decoders of each user are serially connected through a sparse code multiple access detector, so that the user who decodes later can utilize the mutual information of the users who decoded earlier. Thus, the R-SDD receiver has a serial decoding structure.

[0140] In each external iteration, the R-SDD receiver uses a decoding order controller to prioritize users with higher confidence levels, achieving serial decoding and dynamic decoding order reordering. Thanks to the above design, the R-SDD receiver can enable all users to make full use of the external information provided by the decoded users, accelerating convergence. At the same time, the external iteration can be stopped when the slowest convergent user successfully decodes, effectively reducing complexity.

[0141] In one specific embodiment of this example, the sparse code multiple access detector is specifically used for: when receiving received signals superimposed from multiple users, determining the initial posterior log-likelihood ratio of each user; performing message passing iterative detection using the received signals and each initial posterior log-likelihood ratio, and outputting the first prior log-likelihood ratio of each user; and performing message passing iterative detection using the updated initial posterior log-likelihood ratio corresponding to the current first posterior log-likelihood ratio for undecoded users, and determining the first prior log-likelihood ratio of the undecoded users.

[0142] The channel decoder is specifically used for: decoding based on the first prior log-likelihood ratio of the user to be decoded, and determining the corresponding first posterior log-likelihood ratio; performing decoding verification using the first posterior log-likelihood ratio, and determining whether the user to be decoded is a successful decoder or a failed decoder based on the result of whether the decoding was successful; until the first posterior log-likelihood ratio of each user is determined and updated to a successful decoder or a failed decoder, and the external iteration round is updated.

[0143] The decoding order controller is specifically used to: calculate the real-time confidence level based on each first prior log-likelihood ratio, sort and determine the real-time confidence level order; and select the user with the highest confidence level as the user to be decoded according to the real-time confidence level order.

[0144] In a more specific implementation of this embodiment, message passing iterative detection is performed using the received signal and each initialized posterior log-likelihood ratio, outputting the first prior log-likelihood ratio for each user, including:

[0145] Based on the initial posterior log-likelihood ratio, the message is iteratively passed to determine the prior log-likelihood ratio of any user in any current passing round.

[0146] If the current transmission round is 1, the mean absolute change is calculated by using the initial posterior log-likelihood ratio of any user and the prior log-likelihood ratio of the current transmission round.

[0147] If the current transmission round is greater than 1, the average absolute value change is calculated by comparing the prior log-likelihood ratio of any user in the previous transmission round with the prior log-likelihood ratio of the current transmission round.

[0148] When the change in the average absolute value is less than the change threshold or the current transmission round reaches the transmission round threshold, the prior log-likelihood ratio of the current transmission round is output as the first prior log-likelihood ratio of the user to be decoded.

[0149] It should be noted that the R-SDD receiver also introduces an intelligent early stopping mechanism for the MPA detector. This mechanism determines whether the information has converged by measuring the change in the average absolute value of the log-likelihood ratio. This mechanism leverages the characteristic that the MPA detector has already completed most of the effective information exchange in the first few iterations, thus avoiding subsequent invalid computations.

[0150] In one specific implementation of this embodiment, the channel decoder is specifically used to: perform decoding verification using the hard decision result of the first posterior log-likelihood ratio of the user to be decoded; if the decoding verification is passed, the user is determined to be a successful decoder, and the corresponding hard decision result is used as the decoded bit; if there is a hard decision result that fails the decoding verification, the user is determined to be a failed decoder.

[0151] In one specific implementation of this embodiment, the real-time confidence level is the average mutual information based on the prior log-likelihood ratio.

[0152] In one specific embodiment of this example, the sparse code multiple access detector is specifically configured to: perform message passing iterative detection on undecoded users based on the received signal and each first posterior log-likelihood ratio, and output the second prior log-likelihood ratio of each undecoded user; perform message passing iterative detection on undecoded users with the current second posterior log-likelihood ratio corresponding to each updated first posterior log-likelihood ratio, and determine the second prior log-likelihood ratio of the undecoded user; until the second posterior log-likelihood ratio of each undecoded user in the previous external iteration round is determined and updated to either a successfully decoded user or an unsuccessfully decoded user, and the external iteration round is updated.

[0153] The channel decoder is specifically used for: decoding based on the second prior log-likelihood ratio of the user to be decoded, generating the corresponding second posterior log-likelihood ratio; using the second posterior log-likelihood ratio for decoding verification, and determining whether the user to be decoded is a new successful decoding user or a new unsuccessful decoding user based on the determination result of whether the decoding was successful.

[0154] The decoding order controller is specifically used to: sort and determine the real-time confidence order by using the real-time confidence levels of each second prior log-likelihood ratio; and select the user with the highest confidence level as the user to be decoded according to the real-time confidence order.

[0155] In this embodiment of the invention, a serial decoding structure with serial external iterations is adopted. At the same time, the decoding timing of users is dynamically adjusted in each round of external iteration by the confidence order, and the user with the "lowest confidence" is arranged to be processed last, so that it can benefit from the latest soft information output of other users. In addition, since the user who failed to decode is dynamically determined to proceed to the next round of iteration in each round of external iteration, this not only saves computing resources, but also allows the number of decoding attempts to be set to any integer according to hardware conditions. Overall, the higher mutual information propagation efficiency enables the R-SDD receiver to have a lower bit error rate and lower computational complexity, achieving a more flexible trade-off between performance and complexity.

[0156] Please see Figure 8 The sparse code multiple access system provided in Embodiment 3 of the present invention includes: a transmitter and a serial rearrangement receiver based on sparse code multiple access as described in Embodiment 2 of the present invention;

[0157] A transmitter is used to encode and map the bit sequences of information from multiple users, then transmit them to a receiver.

[0158] A serial rearrangement receiver based on sparse code multiple access is used to receive the received signal transmitted by the transmitter and decode it to output a decoded bit sequence.

[0159] It should be noted that the transmitter includes a channel encoder and a sparse code encoder. For the specific processing principle, please refer to the existing technology. Thanks to the design of the R-SDD receiver, the R-SDD receiver enables all users to make full use of the external information provided by the decoded users, which accelerates the overall convergence of the system. At the same time, the system can stop external iteration when the slowest convergent user successfully decodes, which effectively reduces the system complexity and allows the number of decoding times to be set to any integer according to the hardware conditions, thus achieving flexibility and efficiency optimization.

[0160] Embodiment 4 of the present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program; when the computer program is executed by the processor, the processor performs the steps of the serial rearrangement reception method based on sparse code multiple access as described in any of the above embodiments.

[0161] Embodiment 5 of the present invention also provides a computer-readable storage medium storing a computer program / instructions thereon, which, when executed by a processor, implements the steps of the serial rearrangement reception method based on sparse code multiple access as described in any of the above embodiments.

[0162] Embodiment 6 of the present invention also provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the serial rearrangement reception method based on sparse code multiple access as described in any of the above embodiments.

[0163] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the system and receiver described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0164] In the several embodiments provided in this application, it should be understood that the disclosed systems, receivers, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or modules may be electrical, mechanical, or other forms.

[0165] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0166] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0167] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0168] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of serially-reordered reception based on sparse code multiple access, characterized in that, The method comprises the following steps: When receiving a received signal of superimposed transmission of multiple users, first a priori log likelihood ratios (LLRs) are determined based on the received signal and initialized a posteriori LLRs of the users by serial message passing iterative detection, and then external iterations of decoding and decoding check are performed according to a real-time confidence order corresponding to the first a priori LLRs, so as to determine first a posteriori LLRs of the users and update the users into successfully decoded users or unsuccessfully decoded users, and update an external iteration round; It is judged whether there is an unsuccessfully decoded user and whether the external iteration round reaches an external round threshold; If there is an unsuccessfully decoded user and the external iteration round does not reach the external round threshold, then external iterations of the unsuccessfully decoded users are performed by using the received signal and the first a posteriori LLRs of the users in series, so as to determine second a posteriori LLRs of the unsuccessfully decoded users and update the users into successfully decoded users or unsuccessfully decoded users, and update the external iteration round; When it is determined that there is no unsuccessfully decoded user or the external iteration round reaches the external round threshold, a decoded bit sequence composed of decoded bits of the users is output.

2. The method of claim 1, wherein, The method of determining the first a priori LLRs when receiving the received signal of superimposed transmission of the multiple users based on the received signal and the initialized a posteriori LLRs of the users by serial message passing iterative detection, and performing the external iterations of decoding and decoding check according to the real-time confidence order corresponding to the first a priori LLRs, so as to determine the first a posteriori LLRs of the users and update the users into the successfully decoded users or the unsuccessfully decoded users, and update the external iteration round, comprises the following steps: When receiving the received signal of superimposed transmission of the multiple users, the initialized a posteriori LLRs of the users are determined; Message passing iterative detection is performed by using the received signal and the initialized a posteriori LLRs, so as to output the first a priori LLRs of the users; Real-time confidences are calculated according to the first a priori LLRs, and a real-time confidence order is determined by sorting; According to the real-time confidence order, a user with the highest confidence is selected as a user to be decoded; Decoding is performed based on the first a priori LLR of the user to be decoded, so as to determine a corresponding first a posteriori LLR; Decoding check is performed by using the first a posteriori LLR, and a determination result of whether decoding is successful is used to determine that the user to be decoded is a successfully decoded user or an unsuccessfully decoded user; Message passing iterative detection is performed on the unsuccessfully decoded users by using the current first a posteriori LLR corresponding to the updated initialized a posteriori LLRs, so as to determine a new real-time confidence order; According to the real-time confidence order, a user with the highest confidence is selected as a new user to be decoded, and decoding is performed until the first a posteriori LLRs of the users are determined and the users are updated into the successfully decoded users or the unsuccessfully decoded users, and the external iteration round is updated.

3. The method of claim 2, wherein, The method of performing message passing iterative detection by using the initialized a posteriori LLRs, so as to output the first a priori LLRs of the users, comprises the following steps: Message iterative passing is performed based on the initialized a posteriori LLRs, so as to determine a priori LLR of any user at any current passing round; If the current passing round is 1, then an average absolute value change is calculated by using the initialized a posteriori LLR of any user and the priori LLR at the current passing round. If the current passing round is greater than 1, an average absolute value change is calculated by using a priori log-likelihood ratio of any user in the last passing round and a priori log-likelihood ratio of the current passing round; When the average absolute value change is less than a change threshold or the current passing round reaches a passing round threshold, the priori log-likelihood ratio of the current passing round is output as the first priori log-likelihood ratio of any user.

4. The method of claim 2, wherein, The decoding check using the first posteriori log-likelihood ratio, and determining the user to be decoded as a successfully decoded user or a unsuccessfully decoded user according to the determination result of whether the decoding is successful, comprises: Decoding check using the hard decision result of the first posteriori log-likelihood ratio of the user to be decoded; If the decoding check is passed, the user to be decoded is determined as a successfully decoded user, and the corresponding hard decision result is taken as a decoded bit; If there is a hard decision result that fails the decoding check, the corresponding user to be decoded is determined as a unsuccessfully decoded user.

5. The method of claim 1, wherein, The real-time confidence is the average mutual information based on the priori log-likelihood ratio.

6. A serial-reordering receiver based on sparse code multiple access, characterized in that, Comprise: a sparse code multiple access detector, a channel decoder and a decoding order controller; the sparse code multiple access detector is configured to: based on the received signal of the superimposed transmission of the plurality of users, and the initialized posteriori log-likelihood ratio or the first posteriori log-likelihood ratio of each user, perform message passing iterative detection on each user or each unsuccessfully decoded user, and correspondingly determine the first posteriori log-likelihood ratio of each user or the second posteriori log-likelihood ratio of each unsuccessfully decoded user; the channel decoder is configured to: based on the first posteriori log-likelihood ratio or the second posteriori log-likelihood ratio, perform decoding and decoding check, determine the first posteriori log-likelihood ratio of each user or the second posteriori log-likelihood ratio of each unsuccessfully decoded user, update the successfully decoded user or the unsuccessfully decoded user and the outer iteration round according to the first posteriori log-likelihood ratio or the second posteriori log-likelihood ratio, and determine whether there is an unsuccessfully decoded user and whether the outer iteration round reaches an outer round threshold, and when it is determined that there is no unsuccessfully decoded user or the outer iteration round reaches the outer round threshold, output a decoded bit sequence composed of the decoded bits of each user; the decoding order controller is configured to: determine a real-time confidence order using the real-time confidence of the first posteriori log-likelihood ratio, or if there is an unsuccessfully decoded user and the outer iteration round does not reach the outer round threshold, determine a real-time confidence order using the real-time confidence of the second posteriori log-likelihood ratio of each unsuccessfully decoded user, and control the sparse code multiple access detector and the channel decoder to perform message passing iterative detection, decoding and decoding check in series according to the real-time confidence order.

7. A sparse code multiple access system, characterized by, Comprise: a transmitter and the serial rearrangement receiver based on sparse code multiple access of claim 6; the transmitter is configured to superimpose and transmit the information bit sequence of the plurality of users to the receiver after encoding and mapping; the serial rearrangement receiver based on sparse code multiple access is configured to receive the received signal transmitted by the transmitter, and perform decoding to output a decoded bit sequence.

8. A computer device, comprising: A computer program product comprising a memory having computer program stored therein and a processor, wherein the computer program is executable by the processor to cause the processor to perform the steps of the method of serial rearranged reception based on sparse code multiple access according to any one of claims 1-5.

9. A computer readable storage medium having stored thereon computer programs / instructions, characterized in that, The computer program / instructions, when executed by the processor, implement the steps of the method of serial rearranged reception based on sparse code multiple access according to any one of claims 1-5.

10. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instructions, when executed by the processor, implement the steps of the method of serial rearranged reception based on sparse code multiple access according to any one of claims 1-5.

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