近年來，極化碼獲得了許多的關注，並且被選為5G規格中增強型行動寬頻通訊場景下使用的錯誤更正碼。極化碼常規的解碼方法有順續消去法(SC)和保留更多條路徑的順續消去列表法(SCL)，但由於它們的解碼必須照順序且需要先前解碼的結果作為輸入，所以造成了極大的時間延遲，然而通訊最重要的就是講求傳送、接收的速度不僅要快，錯誤率還要越低越好，於是簡化順續消去法(SSC)和快速簡化順續消去法(FSSC)被提出，之後也有了簡化順續消去列表法(SSCL)和快速簡化順續消去列表法(FSSCL)，以上方法都可以在僅造成一些可忽略的錯誤率衰減或甚至是與SC、SCL相同錯誤率的情況下，大大得降低時間延遲。
本篇論文提出了以SSC、FSSC、SSCL和FSSCL為概念的延伸想法，稱為增強型的快速順續消去法(EFSSC)和增強型的快速順續消去列表法(EFSSCL)，將舊有的知識與新做法做結合，使得時間延遲能夠再降到更低，且不會造成更大的錯誤率衰減，並最後會展示區塊錯誤率(BLER)的效能以及討論減少的時間延遲。

During the past few years, Polar Codes has gained lots of attention and has been selected as an error-correcting code for the 5th generation of mobile broadband standard. The conventional decodings of Polar codes are Successive-Cancellation(SC) and Successive-Cancellation List (SCL) which keeps more than one path to decode. Due to the successive decision process, it must have the previous decisions as input to decide the next decision, and thus causes significant latency. The most important thing in communication is to pursue fast reception with low error rate. To reduce latency, some methods have been proposed, namely simplified successive cancellation(SSC) and fast simplified successive cancellation(FSSC). Also, there are schemes which keeps more than one path, namely simplified successive cancellation list(SSCL), fast simplified successive cancellation list(FSSCL). All of the methods reduce latency significantly and only suffer negligible error performance degradation or even no error performance degradation as compared to SC decoding and SCL decoding.
In this work, we proposed some new ideas that can be seen as being extended from SSC, FSSC, SSCL, FSSCL. We call it enhanced fast simplified successive cancellation(EFSSC). It can achieve lower computation latency and do not affect the block error rate (BLER) performance. Its BLER performance and the analysis of latency reduction as compared to SC and SCL are also presented.

[1]E. Arikan, "Channel polarization: A method for constructing capacity-achieving codes," IEEE International Symposium on Information Theory, pp. 1173-1177, 2008.
[2]E. Arikan, "Channel Polarization: A Method for Constructing Capacity-Achieving Codes for Symmetric Binary-Input Memoryless Channels," IEEE Transactions on Information Theory, vol. 55, no. 7, pp. 3051-3073, 2009.
[3]C. Sae-Young, T. J. Richardson, and R. L. Urbanke, "Analysis of sum-product decoding of low-density parity-check codes using a Gaussian approximation," IEEE Transactions on Information Theory, vol. 47, no. 2, pp. 657-670, 2001.
[4]G. He et al., "Beta-Expansion: A Theoretical Framework for Fast and Recursive Construction of Polar Codes," IEEE Global Communications Conference, pp. 1-6, 2017.
[5]"ETSI TS 138 212 V15.2.0 Technical Specification - 5G, NR, Multiplexing and channel coding,",ETSI, July 2018.
[6]C. Schürch, "A partial order for the synthesized channels of a polar code," IEEE International Symposium on Information Theory (ISIT), pp. 220-224, 2016.
[7] H. Huawei, "3GPP, R1-167209, Polar code design and rate matching," 2016.
[8] K. Niu and K. Chen, "CRC-Aided Decoding of Polar Codes," IEEE Communications Letters, vol. 16, no. 10, pp. 1668-1671, 2012.
[9] K. Niu and K. Chen, "Stack decoding of polar codes," Electronics Letters, vol. 48, no. 12, pp. 695-697, 2012.
[10] I. Tal and A. Vardy, "List Decoding of Polar Codes," IEEE Transactions on Information Theory, vol. 61, no. 5, pp. 2213-2226, 2015.
[11] A. Balatsoukas-Stimming, M. B. Parizi, and A. Burg, "LLR-Based Successive Cancellation List Decoding of Polar Codes," IEEE Transactions on Signal Processing, vol. 63, no. 19, pp. 5165-5179, 2015.
[12]A. Alamdar-Yazdi and F. R. Kschischang, "A Simplified Successive-Cancellation Decoder for Polar Codes," IEEE Communications Letters, vol. 15, no. 12, pp. 1378-1380, 2011.
[13]G. Sarkis, P. Giard, A. Vardy, C. Thibeault, and W. J. Gross, "Fast Polar Decoders: Algorithm and Implementation," IEEE Journal on Selected Areas in Communications, vol. 32, no. 5, pp. 946-957, 2014.
[14]S. A. Hashemi, C. Condo, and W. J. Gross, "Simplified Successive-Cancellation List decoding of polar codes," IEEE International Symposium on Information Theory (ISIT), pp. 815-819, 2016.
[15]S. A. Hashemi, C. Condo, and W. J. Gross, "A Fast Polar Code List Decoder Architecture Based on Sphere Decoding," IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 63, no. 12, pp. 2368-2380, 2016.