# Improved Adaptive Successive Cancellation List Decoding of Polar Codes  
[PERSON]  
1 College of Information Engineering, China Jiliang University, Hangzhou 310018, China; [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (J.H. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (B.H.) [PERSON]  
1 College of Information Engineering, China Jiliang University, Hangzhou 310018, China; [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (J.H. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (B.H.) [PERSON]  
2 Binjiang College, Nanjing University of Information Science & Technology, Wuxi 214105, China 222221  
codes. Subsequently, [PERSON] et al. proposed a CA-SCL algorithm, which selects reliable paths of SCL in [4] through the cyclic redundancy check aided (CRC-aided) decoding of polar codes. The algorithm further improves the performance of SCL, and when \(L\) is big enough, the performance of the algorithm can approach the maximum likelihood probability. In [5], a successive cancellation priority (SCP) decoding algorithm was proposed to reduce the decoding delay by avoiding the expansion of some unnecessary paths. In [6], a new SCL decoding was proposed by using multiple CRC codes, which can improve the performance of decoding. However, using multiple CRC codes increases memory and time complexity, which can be reduced by optimizing CRC positions in combination with a modified decoding operation. [PERSON] et al. proposed the bit-flip algorithm for the CA-SCL algorithm, which can improve the decoding performance of polar codes compared to CRC-aided decoding of polar codes [7]. Although the SCL decoding algorithm has excellent decoding performance by adding CRC, its memory complexity and time complexity increase with the increase of \(L\). The method of reducing the complexity in SCL decoding is mainly divided into two types. On the one hand, the computational parallelism of SCL is improved and the computational process is simplified to reduce the time complexity of SCL decoding. In [8], a method for estimating path metrics (PM) by using Rate-1 and SPC nodes for the SSC and SCL algorithm in parallel was proposed. This method greatly reduces the time complexity of the SCL algorithm, but it brings about the uncertainty of the estimation results and leads to performance loss. Based on this, the simplified successive cancellation list (SSCL) algorithm proposed in [9] can identify and simplify the redundancy calculation in SCL. This method greatly reduces the time complexity without loss of performance. On the other hand, it is the optimization of path management in SCL decoding. [PERSON] et al. proposed the segmented CRC-aided successive cancellation list (SCA-SCL) decoding technique which can reduce the complexity of decoding [10]. Path selection can also be optimized. In [11; 12; 13; 14; 15], different schemes for optimizing \(L\) paths were proposed. In order to reduce the complexity of SCL, [PERSON] et al. proposed a more convenient method to select \(L\) paths from \(2L\) paths based on RS sorting [16], which reduces the complexity of selecting paths in SCL from \(O\big{(}NL\log_{2}L\big{)}\) to \(O(NL)\). In [17], they proposed a method to simplify the number of paths retained in the SCL decoding process according to the transition probability, which realizes SCL decoding with variable \(L\) and also reduces the complexity. [PERSON] et al. proposed partitioned SCL (PSCL) decoding technique which can reduce the required memory [18]. Although the method above reduces the complexity of SCL to a certain extent, they all have a certain impact on the performance of SCL. Based on the PSCL algorithm, the generalized PSCL (GPSCL) algorithm proposed by [PERSON] et al. can improve performance under the same complexity [19]. [PERSON] et al. put forward the adaptive SCL (AD-SCL) decoding algorithm [20], which reduces the complexity of SCL in the case of specified performance. The difference between AD-SCL and CA-SCL lies in that AD-SCL sets the minimum path value and the maximum path value, while SCL starts to decode from \(L_{\text{min}}\).