The A* algorithm for decoding linear block codes is an efficient tree-search method for decoding short linear block codes. The information contained in the parity bits are potentially useful for reducing the edges needed in the tree search. We propose to extract the information embedded in the parity bits by considering sums of parity bits which can be decided by part of the message bits. Analysis for the number of required message bits for obtaining sums of parity bits is provided. The information contained in the parity bits can help to reduce the number of search tree edges.

The A* algorithm is an efficient method for decoding short linear block code based on tree search. However, it may suffer very long decoding latency in the worst-case channel condition. In this paper, we propose to apply some restrictions on the Hamming weights of search paths in the tree-search decoding. Simulation results show that with proper selection of path constraints in the A* algorithm, the worst-case decoding complexity (or latency) can be significantly reduced with only slight sacrifice of the bit error rates.

The A* algorithm for decoding linear block codes is known to be an efficient tree-search method for decoding short linear block codes. We propose to employ the early acquired information of some parity bits to speed up the tree search. Analysis for the number of required information bits for obtaining the parity bits is provided. In addition, two versions of the modified A* algorithm which take advantage of the advanced information of parity bits are provided. Simulation results show that there is advantage in reducing the number of search tree edges in each proposed version as compared with two existing A* algorithms which do not consider the early information of parity bits.

Applying interblock memory to binary linear block codes is a method to increase the transmission reliability by increasing the correlation among codewords. In this paper, we consider short block coding with interblock memory. Since short block codes can be efficiently decoded by employing the A* Algorithm, we investigate the performance of short block coding with interblock memory using the A* decoding. In addition, we propose a simple method which can alleviate the effect of error propagation resulting from interblock memory.

In this paper, a modified version of the A* algorithm for decoding linear block codes is proposed. By employing the early acquired information for some parity bits, we can improve the efficiency of the A* decoding algorithm.