论文标题
稀疏代码多访问的低复杂性迭代接收器设计
Low Complexity Iterative Receiver Design for Sparse Code Multiple Access
论文作者
论文摘要
稀疏代码多重访问（SCMA）是未来所有非正交多访问技术中最有前途的方法之一。与其他一些非正交多访问技术（例如低密度签名（LDS））相比，由于SCMA代码字的成型增益，SCMA可以实现更好的性能。然而，尽管代码字的稀疏性，但SCMA使用的当前消息传递算法（MPA）的解码复杂性仍然很高。在本文中，通过探索SCMA代码字的晶格结构，我们提出了基于列表球体解码（LSD）的低复杂性解码算法。 LSD避免详尽地搜索所有可能的假设，并且仅考虑在超级球中发出信号。由于可以将LSD视为深度优先的树搜索算法，因此我们进一步提出了几种方法来修剪冗余访问的节点，以减少搜索树的大小。仿真结果表明，所提出的算法可以大大降低解码的复杂性，而与现有算法相比，性能损失可以忽略不计。
Sparse code multiple access (SCMA) is one of the most promising methods among all the non-orthogonal multiple access techniques in the future 5G communication. Compared with some other non-orthogonal multiple access techniques such as low density signature (LDS), SCMA can achieve better performance due to the shaping gain of the SCMA codewords. However, despite of the sparsity of the codewords, the decoding complexity of the current message passing algorithm (MPA) utilized by SCMA is still prohibitively high. In this paper, by exploring the lattice structure of SCMA codewords, we propose a low complexity decoding algorithm based on list sphere decoding (LSD). The LSD avoids the exhaustive search for all possible hypotheses and only considers signal within a hypersphere. As LSD can be viewed a depth-first tree search algorithm, we further propose several methods to prune the redundancy visited nodes in order to reduce the size of the search tree. Simulation results show that the proposed algorithm can reduce the decoding complexity substantially while the performance loss compared with the existing algorithm is negligible.
