基于网络编码的稀疏码分多址接入HARQ方案  

HARQ scheme for sparse code multiple access based on network coding

作　　者：赖恪 雷菁[1] 刘伟[1] 文磊 LAI Ke;LEI Jing;LIU Wei;WEN Lei(College of Electronic Science and Technology,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]国防科技大学电子科学学院,湖南长沙410073

出　　处：《通信学报》2022年第9期57-69,共13页Journal on Communications

基　　金：湖南省自然科学基金资助项目(No.2021JJ30777);国防科技基金资助项目(No.3101168);基础加强计划技术领域基金资助项目。

摘　　要：为了应对后5G以及未来6G时代对可靠性、时延以及吞吐量的严苛要求,针对低密度奇偶校验(LDPC)码编码的稀疏码分多址接入(SCMA)技术,提出了一种网络编码(NC)辅助的新型HARQ方案。该方案在多用户场景下,将各用户传输过程中处于2个不同时隙的错误包利用NC进行异或操作后重传。这样一来,一方面,只需要一次重传即可完成2个数据包的信息传输;另一方面,重传的数据包在接收端将会获得额外的编码增益。同时,考虑到LDPC和SCMA译码结构的相似性,以及NC译码器的单校验节点特征,基于消息传递算法(MPA),设计了SCMA、LDPC以及NC的联合迭代算法。该算法使接收端能够充分利用当下以及先前传输所获取的软信息,进而发挥NC所带来的编码增益。仿真结果表明,所提方案能够获得比SCMA的传统HARQ方案更高的吞吐量以及可靠性。To fulfill the stringent reliability and throughput demand of the beyond-5G and the forthcoming 6G,a novel network coding(NC)based hybrid automatic retransmission request(HARQ)for low-density parity check(LDPC)coded SCMA was proposed.Two incorrectly received packets from different time slots were retransmitted by using NC principle under multi-user scenario.By doing so,the information came from two packets could be conveyed in one retransmission.Moreover,extra coding gain could be attained at the receiver.Furthermore,since the similarity between SCMA detector and LDPC decoder,and the one check node feature of NC decoder,a SCMA,LDPC and NC joint decoder based on message passing algorithm(MPA)was proposed.The proposed scheme could fully utilize the soft messages come from current and previous transmissions,and thus exploiting satisfied coding gain from NC.Simulation results show that the superiority of the proposed novel HARQ scheme for SCMA over the conventional HARQ on both throughput and reliability.

关 键 词：稀疏码分多址接入 混合自动重传请求 网络编码 低密度奇偶校验 吞吐量 

分 类 号：TN92[电子电信—通信与信息系统]