Research On Soft-Decision Decoding Algorithms Of RS Codes And Its Implementation In SOPC Technology

Reed-Solomon codes, which possess very reasonable and rigorous algebraic structure, consummate and efficient hard-decision decoding algorithms and excellent burst error and random error correction ability ,are the very celebrated class of linear block codes. Now, RS codes are widely used in many existing systems, such as deep space communications, magnetic recording devices and digital media transmission. However, RS codes lack of soft-decision decoding algorithms simple and easy to implement, which greatly restricted RS codes to be used in the future communication systems. Therefore, research on the soft-decision decoding algorithms of RS codes and implementing them in new technologies have important theoretical significance and value of engineering applications.This thesis first introduces some basis of RS codes, including the encoding and hard-decision decoding principles, and then lists some existing reliability-based soft-decision decoding algorithm for RS codes. Based on these, this paper focuses on Chase2 soft-decision decoding algorithm and adaptive-belief-propagation(ABP) soft-decision decoding algorithm, analyses the performance of the two algorithms, and compares the implementation complexity in perspective of binary-field operations between the two algorithms. Moreover,Chase2 soft-decision decoding algorithm and signal to noise ratio(SNR) estimation are combined together, replacement digit is selected according to the channel quality, which effectively balances computational complexity and decoding gain.Eventually,Chase2 soft-decision decoding algorithm is implemented on the hardware platform of wireless sensor network nodes. This measure can improve the accuracy of data communications and boost the coverage of the single node. During the implementation, novel system-on-a-programmable-chip(SOPC) technology is adopted. Through appending custom Galois-field instructions, floating-point instructions and custom Avalon peripherals, the NiosII CPU can ensure the performance of Chase2 algorithm and reduces the number of execution instructions, which lead to a high decoding rate, and these improvements reflect the advantage of implementing Chase2 algorithm in SOPC technology.