稀疏码分多址收发端改进方案的设计

Improved scheme design of sparse code multiple access transceiver

为降低传统稀疏码分多址接入(sparse code multiple access, SCMA)系统的译码复杂度,同时保证系统误比特率(bit error ratio, BER)性能,考虑信道质量因素提出SCMA系统收发端改进方案。在接收端,提出基于信道质量动态选择节点改进消息传递算法(message passing algorithm, MPA),在串行策略基础上对节点更新顺序进行合理排序,减少算法迭代次数,以降低译码复杂度;同时为补偿付出的BER性能代价,在发送端基于信道质量设计动态自适应更新因子图方案,为用户节点匹配高信道增益的资源节点组合,并且考虑到用户的公平性,令上轮更新因子图时信道增益最低的用户节点优先匹配。仿真实验证明,所提改进方案在保证BER性能和各用户公平性前提下有效降低系统译码复杂度。

In order to reduce the decoding complexity of the traditional sparse code multiple access(SCMA) system and guarantee the bit error ratio(BER) performance of the system, improved SCMA transceiver system is proposed based on the channel quality factor. An improved message passing algorithm(MPA) dynamically selects nodes based on channel quality is proposed at the receiver, which sorts the node update sequence reasonably on the basis of serial strategy, thereby decreasing the number of iterations of the algorithm to reduce the decoding complexity. At the same time, due to compensate BER performance cost, a dynamic adaptive updating factor graph scheme based on channel quality is designed at the transmitter, which matches resource node combination with high channel gain for user nodes. Besides, considering the fairness of users, the user nodes with the lowest channel gain in the last round of updating factor graph are given priority to match. Simulation experiments show that the proposed improved system can effectively reduce the decoding complexity under the premise of ensuring BER performance and fairness of each user.