A UEP LT Codes Design with Feedback for Underwater Communication

Danfeng Zhao,Jiaxi Si,Jie Wen

doi:10.1155/2016/2390734

Abstract

To satisfy the performance requirement of LT codes with Unequal Erasure Protection (UEP) in underwater environment, the Weighted Expanding Window Fountain (WEWF) code is proposed in this paper. The WEWF codes can achieve strong UEP property by nonuniformly selecting input symbols within each window. To overcome the disadvantages in terms of redundancy in the lower prioritized segments, Correlation Chain Feedback (CCFB) is also introduced to help the transmitter to precisely adjust the encoding scheme. Asymptotic analysis and simulation results demonstrate that the proposed approach can achieve lower symbol error rate and less overall redundancy in the underwater acoustic sensor networks.

Highlights

Up to now, digital fountain codes (DFC) have become an efficient data transmission scheme for underwater acoustic sensor networks (UASNs) [1,2,3], and the most commonly used DFC are LT codes and Raptor codes
The simulation is performed from two aspects: one is based on VS2010 to test and verify the performance of Weighted Expanding Window Fountain (WEWF) codes and the other is established on OPNET modeler in order to demonstrate that the proposed scheme is suitable for UASNs
Under the condition of ε = 0.25, the Symbol Erasure Rate (SER) of Weighted LT (WLT) codes is the lowest which equals 2.083×10−6, while the WEWF codes have a SER of 9 × 10−6 followed by EWF codes with SER of 1.458 × 10−5

Summary

Introduction

Digital fountain codes (DFC) have become an efficient data transmission scheme for underwater acoustic sensor networks (UASNs) [1,2,3], and the most commonly used DFC are LT codes and Raptor codes. The second, such as the duplication method proposed in [9] and Duplicating-Expanding Window Fountain (D-EWF) codes [10], is based on the idea of virtually increasing the source block size The latter is more superior in terms of UEP performance, at the cost of compromising quite big transmission budget once the original source block size or repeat factors are large. This paper proposes an efficient solution to provide UEP for energy-restricted underwater environment with harsh channel conditions by utilizing the abovementioned method to improve the performance of the more important data and simultaneously introducing the Correlation Chain Feedback to optimize the overall redundancy.

Weighted Expanding Window Fountain Codes

Simulation Results and Analysis

Conclusion