AN EFFICIENT ADAPTIVE CIRCULAR VITERBI ALGORITHM FOR DECODING GENERALIZED TAILBITING CONVOLUTIONAL-CODES
AN EFFICIENT ADAPTIVE CIRCULAR VITERBI ALGORITHM FOR DECODING GENERALIZED TAILBITING CONVOLUTIONAL-CODES
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DOI：
10.1109/25.282266
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发表时间：
1994-02-01
影响因子：
6.8
通讯作者：
SUNDBERG, CEW
中科院分区：
文献类型：
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作者：
COX, RV;SUNDBERG, CEW
为蜂窝移动无线电系统中的许多应用，正在考虑用于卷积代码的Viterbi解码算法。有三类的Viterbi解码器，取决于数据格式的性质：使用有限的路径内存连续解码，用终端尾巴（解码器已知）进行块解码，并在没有已知尾巴的情况下进行块解码。后类也称为解码卷积卷积代码的解码。在这种情况下，编码的消息以相同的状态开始并结束，而接收者未知。在本文中，我们介绍了一类用于卷积卷积代码的Viterbi算法。这些算法用于块状传输，以节省已知尾巴的开销。我们将新算法称为圆形Viterbi算法（CVA）。基本思想是：1）继续传统的无缝连续viterbi通过记录和重复接收到的（软）符号的块来超越块边界； （2）在所有州开始解码过程； 3）结束解码过程，要么以固定的长度自适应。构建和评估了三个强大的自适应停止规则。给出了模拟结果和与先前已知的算法以及最佳算法的比较。随着通道位错误率（BER）的增加，先前报道的迭代算法所需的计算量往往会大大增加。在一个报道的情况下，计算增加了900％以上，而解码的BER从8 x 10（-6）增加到8 x 10（-3）。在同一示例中，计算的CVA增加为11.4％，最坏的情况解码为4 x 10（-3）。我们得出的结论是，对于嘈杂的频道，CVA解码在短时间内的性能，性能比以前发表的迭代算法更好。
Viterbi decoding algorithms for convolutional codes are being considered for a number of applications in cellular mobile radio systems. There are three classes of Viterbi decoders depending on the nature of the formatting of the data: continuous decoding with a finite path memory, blockwise decoding with a terminating tail (known to the decoder), and blockwise decoding without a known tail. The latter class is also known as decoding of tailbiting convolutional codes. In this case, a coded message begins and ends in the same state which is unknown to the receiver. In this paper, we present a class of Viterbi algorithms for tailbiting convolutional codes. These algorithms are used in blockwise transmission to save the overhead of a known tail. We call the new algorithm the circular Viterbi algorithm (CVA). The basic ideas are: 1) continue conventional seamless continuous Viterbi decoding beyond the block boundary by recording and repeating the received block of (soft) symbols; (2) start the decoding process in all states; 3) end the decoding process either adaptively or with a fixed length. Three robust adaptive stopping rules are constructed and evaluated. Simulation results and comparison to previously known algorithms as well as the optimum algorithm are presented. The amount of computation required for previously reported iterative algorithms tends to increase dramatically as the channel bit error rate (BER) increases. In one reported instance, computation increased by over 900% while decoded BER increased from 8 x 10(-6) to 8 x 10(-3). For the same example, the CVA increase in computation was 11.4% and the worst case decoded BER was 4 x 10(-3). We conclude that for noisy channels the CVA decodes in a much shorter time with better performance than previously published iterative algorithms.