基于顺序调度策略的改进型RCM解调算法  

Improved RCM Demodulation Algorithms Based on Sequential Scheduling Strategies

作　　者：张辉恋 Zhang Huilian(College of Electronics and Information Engineering,South-Central University for Nationalities,Wuhan 430074,Chin)

机构地区：[1]中南民族大学电子信息工程学院,湖北武汉430074

出　　处：《信息通信》2018年第7期16-18,共3页Information & Communications

摘　　要：速率可变调制(RCM)是一种可在时变信道上实现平滑的速率自适应的接收端速率自适应技术。现有RCM解调算法中的消息更新采用洪泛的方式,解调收敛速度较慢,针对这一问题,该文提出了两种改进型RCM解调算法,分别是基于标准顺序调度策略的GS-BP解调算法、基于通知动态调度策略的BS-RBP解调算法。在GS-BP解调算法中,消息的更新被根据比特节点的固有顺序划分成组,在每一轮迭代中,消息更新逐组进行,这使得前面分组中已更新的最新消息在本轮迭代的后续分组中的消息更新过程中被充分地利用起来,有助于加快解调的收敛速度。在BS-RBP解调算法中,由比特节点传向符号节点(B2S)的消息的残差被当作消息可靠度的度量标准,它被用来区分消息更新的优先级,这种异步消息更新策略有利于迭代中的最新消息被充分利用。仿真结果表明,相较于RCM的传统BP解调算法,所提两种解调算法都可以显著地加快解调收敛速度。Rate compatible modulation（RCM） is a method that can achieve smooth rate adaptation on time-varying channel. The message updates in the existing RCM demodulation algorithms take the form of flooding, and the convergence rate of demodulation is slow. To mitigate this problem,we propose two improved RCM demodulation algorithms, namely, the GS-BP demodulation algorithm which is based on the standard sequential scheduling strategies and the BS-RBP demodulation algorithm which is based on the informed dynamic scheduling strategies. In the GS-BP demodulation algorithm, message updates are divided into groups according to the inherent order of the bit nodes. In each round of iteration, message updates are performed group by group, which makes the latest updated messages in the previous groups fully utilized in the message update process of the subsequent groups of the current iteration, which helps to speed up the convergence rate of the demodulation. In BS-RBP demodulation algorithm, the residuals of the messages transmitted from bit nodes to symbol nodes（B2 S） are regarded as metrics of the reliabilities of messages, and the priorities of the message updates are differentiated according to these metrics. This asynchronous message update strategy facilitates the best use of the latest messages in iterations. Simulation results show that compared with the conventional BP demodulation algorithm of RCM, both of the two proposed demodulation algorithms can significantly accelerate the convergence rate of demodulation.

关 键 词：速率可变调制 置信传播算法 顺序调度策略 解调 

分 类 号：TN929.5[电子电信—通信与信息系统]