基于纠删码的速率自适应传输方法研究

发布时间：2018-03-24 21:11

本文选题：纠删码　切入点：导码　出处：《华中科技大学》2014年硕士论文

【摘要】：无线通信系统在时变信道条件下获得高吞吐率的挑战在于传输速率如何更好的匹配信道条件。基于纠删码的无速率技术与自适应编码调制技术相比具有自适应精度高，物理层实现复杂度低以及具有后向兼容协议等特点。基于纠删码的无速率技术对于解决无线通信系统在时变条件下缩小系统实际频谱效率与香农限之间的间隙以及研究无速率特性有现实研究意义。本文基于纠删码搭建了速率自适应的通信系统，该系统主要包含raptor编解码，速率自适应策略以及BP译码三个部分。Raptor编解码是整个系统的核心，也是决定整个通信系统频谱效率的关键部分。自适应策略决定哪些比特参与译码，，自适应策略的性能关系到速率自适应能否精确匹配时变信道条件，所以本文研究了删余策略和增量冗余策略对系统速率自适应性能的影响。由于BP译码存在一些不足，本文还提出基于导码辅助译码算法以及抑制置信度震荡算法来提升BP译码的性能。基于导码辅助译码算法充分利用已知信息辅助译码，从而能够纠正更多的错误比特，经过实验测试基于导码辅助译码算法能够有效提升节点平均置信度，降低译码复杂度，提升纠删码的纠错能力。抑制置信度震荡算法能够有效的抑制Tanner图中不可避免的环路带来的震荡，从而有效辅助译码器的正确收敛。论文提出软值归零算法来抑制置信度震荡，软值归零算法有效的提升了纠删码的性能。本文研究的基于纠删码的速率自适应技术对于提升系统频谱效率，降低系统实现复杂度，提升系统译码性能有实际应用价值。
[Abstract]:The challenge for wireless communication systems to achieve high throughput in time-varying channels lies in how the transmission rate can better match the channel conditions. The rate free technique based on erasure codes has higher adaptive accuracy than adaptive coding modulation. The implementation complexity of physical layer is low and it has backward compatibility protocol. The rate free technology based on erasure code can reduce the gap between the actual spectrum efficiency and Shannon limit of wireless communication system under time-varying conditions. And the study of rate-free characteristics has practical significance. In this paper, a rate adaptive communication system based on erasure code is built. The system mainly includes raptor coding and decoding, rate adaptive strategy and BP decoding. Raptor coding and decoding is the core of the whole system. The adaptive strategy determines which bits participate in decoding. The performance of the adaptive strategy relates to whether the rate adaptation can accurately match the time-varying channel conditions. In this paper, the effects of censored strategy and incremental redundancy strategy on the adaptive performance of the system are studied. This paper also proposes a new algorithm to improve the performance of BP decoding based on the codec aided decoding algorithm and the suppression of confidence oscillation algorithm, which makes full use of known information to correct more error bits. The experimental results show that the decoding algorithm based on the guide code can effectively improve the average confidence of the node and reduce the decoding complexity. To improve the error-correcting ability of erasure codes. The confidence oscillation algorithm can effectively suppress the oscillation caused by the inevitable loop in the Tanner diagram, thus effectively assist the correct convergence of the decoder. In this paper, a soft-value zeroing algorithm is proposed to suppress the confidence oscillation. Soft value zeroing algorithm effectively improves the performance of erasure codes. The rate adaptive technology based on erasure codes studied in this paper has practical application value in improving the spectral efficiency of the system, reducing the complexity of the system implementation and improving the decoding performance of the system.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN92

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