| After messages pass through the channel, the receiver is always difficult to synchronize with the transmitter, or even can’t be synchronized due to the limitation of manufacturing technology, thus leading to synchronization errors. Synchronization error, which means insert or remove a number of bits in the transmission, would have a disastrous effect on the communication system. Due to synchronization errors are independent, so the receiver is difficult to correct these errors. With the increasing demand of information transmission rate and information storage, synchronization errors occur more frequently in communication systems and storage systems. The channel on which synchronization errors occur is synchronous channel. In a typical synchronous channel, synchronization errors are completely random, which means that insertion error and deletion error do not have any influence on each other, but in some of the latest communication systems, such as bit-patterned media recoding system, insertion errors and deletion errors often occur in pairs. Research on synchronization errors and paired insertion/deletion errors has attracted widespread attention.Low-density parity check code(LDPC) is defined by a sparse parity check matrix, because it has a low decoding complexity and excellent error correction capability, so it is widely used in the synchronous channel codec technologies. In this paper, we will study the synchronization channel encoding and decoding algorithms, give out the elaborate and implement of two coding schemes on bit-level synchronization and symbol-level synchronization. Then we propose a new paired insertion/deletion channel model, and give out a successful simulation and implemented of the coding scheme for the new channel. The main work of this paper is summarized as follows:1. The history of channel coding theory are introduced, and a detailed analysis of the basic theory of LDPC codes is given, then the process of how to seek maximum a posteriori(MAP) is given, which proves that symbol-level decoding algorithm has better performance compared to the bit-level decoding algorithm through the simulation.2. A new paired insertion/deletion channel model is designed, and a detailed analysis ofthis channel is given, then the process of MAP of bit-level on this channel is given out. The simulation of this algorithm shows that the algorithm is effective on this channel.3. It is analyzed that how the channel state transferred when a symbol-level coding algorithm is used on paired insertion/deletion channel, a series of MAP of symbol-level are given, then the simulation proves that the symbol-level coding algorithm is effective on this channel, and also proves that the symbol-level coding algorithm show a better performance than the bit-level coding algorithm. |
