通訊技術日益發展，編碼技術受到相當大的重視。第三代合作夥伴計劃3GPP 在New Radio(NR)裡主張第五代通訊技術將圍繞在三大應用場景，它們分別是:增強型行動寬頻(eMBB)、大規模機器通訊(mMTC)和高可靠低時延通訊(URLLC)。
eMBB通訊場景的錯誤更正碼，資料信道(data channel)採用低密度檢驗碼且控制信道(control channel)採用極化碼。然而極化碼有一個先天限制：碼長為2的冪次方數。為了使碼長能夠匹配各種場景，第五代行動通訊規格提出了三種碼率匹配機制：穿孔(puncturing)、縮短(shortening)及重複(repetition)。
在本篇論文，我們只著重於探討如何針對碼率匹配中的穿孔這項機制，依照基因演算法做優化。我們使用穿孔對應的chromosomes參與基因演算法競爭，過程中發生選擇、突變、交越，並參照高斯近似法(Gaussian approximation, GA)選用區塊正確率為適配函數給分，世代將延續到chromosomes收斂或達到預先設定的最大世代數。
除了前面提到的優化穿孔方案，本篇論文我們也針對不同的穿孔做法使用SC、SCL、BP及improved LDPC-like polar BP比較各自的性能及速率表現。再者，我們除了結合碼率匹配與LDPC-like polar BP解碼也發現電路架構可以再進一步化簡(我們稱其為improved LDPC-like polar BP)。最後若我們對凍結位與資訊位做「列權重交換(RWE)」，可降低將Polar code轉化成improved LDPC-like polar BP後檢驗點於冗餘運算中被移除的機率，也稍稍抑制了某些校驗節點度數。此機制有別於一般我們直接按照通道排序好壞選定資訊通道的做法，而是為了配合Tanner graph度數優化而嘗試不同選擇。此舉又可能在高訊雜比時幫助再進一步提升性能，我們也透過外帶資訊(extrinsic information)、通道容量(channel capacity)等理論分析及驗證列權重交換的效果。

In modern communications, error correction coding is a key technology . The 3rd Generation Partnership Project 3GPP advocates, in New Radio(NR) that the 5th generation communication technology will focus on three major application scenarios, namely: Enhanced Mobile Broadband(eMBB), Massive Machine Type Communications(mMTC), and Ultra-reliable and Low Latency Communications(URLLC).
For error correction in the eMBB communication scenario, the data channel uses low-density check codes(LDPC) and the control channel uses polar codes. However, polar codes suffer one inherent limitation that code length is a power of two. To make the code length match various scenarios, the fifth generation mobile communication specification proposes some rate matching mechanisms. There are three options : puncturing, shortening and repetition.
In this paper, we only focus on how to optimize the puncturing mechanism in code rate matching according to the genetic algorithm. We use chromosomes corresponding to puncturing to participate in genetic algorithm competition. During the process of selection, mutation, and crossover, the block correct rate as computed by Gaussian approximation is selected to be an adaptation function. The generation will continue until the chromosomes converge or reach a preset maximum generation number.
In addition to the optimized puncturing scheme mentioned earlier, we also use SC, SCL, BP and improved LDPC-like polar BP for different puncturing to compare their BLER performance and code-rate performance. Furthermore, in addition to combining rate matching and LDPC-like polar BP decoding, we also found that the circuit architecture can be further simplified (we call it the improved LDPC-like polar BP). Finally, if we perform "row-weight exchanges (RWE)" between the frozen bits and the information bits, the probability that the nodes will be removed from the redundant operation after the polar code is converted to improved LDPC-like polar BP will be reduced, and some of degrees of check node will be slightly suppressed. This mechanism tries different combinations to match with Tanner-graph degree optimization. This may in turn help to further improve performance at high signal-to-noise ratios. We also analyzed and verified the effect of row-weight exchanges through extrinsic information , channel capacity, and so on.

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