مقاله انگلیسی رایگان در مورد تحلیل عملکرد الگوریتم رمزگشایی مبتنی بر قابلیت اطمینان – تیلور و فرانسیس 2022

Abstract

     Demand for transmission using short block length messages has been increased recently in applications including satellite communication, mobile communication, wireless sensor networks, and machine type communications. Unacceptable performance degradation associated with the short block length Turbo codes restricted its use for applications requiring communication with short block length codewords. A novel performance improved reliability-based decoding algorithm for short block length Turbo codes has been formulated and proposed by the authors. The proposed algorithm has a coding gain of 2.45 dB at a BER of 10−3 over AWGN channel with BPSK modulation for a code rate of 14

. The algorithm has a channel adaptive complexity and has shown nearly 82% reduction in the decoding time complexity for the rate 14

 Turbo code at 3 dB SNR. As an extension of this earlier work, a detailed performance analysis of the algorithm on different Turbo codes has been carried out. A four-state Turbo encoder has been used to bring out the key aspects of the level based algorithm which is driven by reliability as the key parameter. The formulated algorithm has been applied to different Turbo encoder structures namely 3GPP LTE and CCSDS Turbo codes and a detailed analysis has been carried out in this paper. Simulation results show a significant improvement in the error correction performance of short block length Turbo codes. The algorithm also leads to a marked improvement in time complexity at high SNRs. The algorithm is an attractive solution for applications requiring communication with short block lengths.

Introduction

     Achieving optimal error correction capability and computational complexity is one of the major challenges in wireless communication. Turbo codes have shown near Shannon capacity approaching performance for longer codeword lengths [1,2]. Iterative Turbo decoder which uses MAP or its variants like Log-MAP or Max-LogMAP as the constituent decoder performs a fixed number of iterations irrespective of the channel conditions and information block size [3]. The BER performance of Turbo codes flattens in moderate to high SNR regions and the same does not improve even with a large number of iterations. This phenomenon is called as “error floor” [4]. Applications like satellite uplink, real-time communication, machine to machine communication, and mobile communication require transmission with short block length Turbo codes [5,6]. The capacity approaching Turbo codes fail to offer acceptable performance when dealing with short block length codewords due to the high error floor and unacceptable coding gain degradation [7,8]. Dynamic channel conditions introduce varying levels of errors during the transmission. The number of errors introduced also varies according to the channel conditions and hence it is necessary to vary the error correction level accordingly, rather than providing a constant level of error correction at all channel conditions.

Conclusion

     The demand for communication with short data blocks is increasing in recent years. Real-time communication and low latency applications require communication with short block length codewords. Strong channel codes are required to ensure reliable transmission over dynamic channel conditions. The demand for communication with short block Turbo codes is increasing in applications like mobile communication, wireless sensor networks, and satellite communication. In this paper, the performance of the novel reliability-based algorithm has been analyzed for 3GPP LTE, and CCSDS Turbo codes. Simulation results show that the algorithm outperforms the conventional iterative Turbo decoder in terms of BER performance. The time complexity of the performanceenhanced reliability-based Turbo decoder shows a clear advantage as SNR increases. The performance flattening at high SNR region is completely eliminated with the proposed decoding algorithm. This is a clear advantage for applications requiring communications with short block length Turbo codes. The algorithm is an attractive solution to achieve reliable and timely transmission of short block length Turbo codes in mobile and satellite communication applications. The proposed algorithm has a coding gain of 2.45 dB at a BER of 10−3 over AWGN channel with BPSK modulation for a code rate of 1 4 . The algorithm has a channel adaptive complexity and has shown nearly 82% reduction in the decoding time complexity for the rate 1 4 Turbo code at 3 dB SNR. The performance analysis of the level based Turbo decoding algorithm gives an insight into an alternate decoding approach for Turbo codes.