Fountain Coding with Weighted Non-uniform Selection for Reliable FSO Communication

Abstract

Free space optical (FSO) communication combines the advantages of optical fiber communication and wireless communication, and is anticipated with a great application prospect. However, the reliability of FSO link is sensitive to the atmospheric condition that imposes a critical challenge on its practice. Channel coding is a promising solution to improve the reliability of FSO link. However, most of the existing coding methods require the continuous knowledge of channel status information (CSI) that is not always perfectly available in FSO system. In this paper, we propose a new fountain coding scheme that does not require continuous CSI feedback for FSO system. Unlike the traditional fountain coding, the proposed scheme selects source packets non-uniformly without feedback information, which helps reduce the coding overhead and achieve a high packet recovery rate. We prototyping a FSO link and emulating an atmospheric channel by using an advanced chamber. The datasets of channel fading and Bit Error Rate (BER) are obtained under various fog conditions. On basis of the datasets, it is demonstrated that the proposed fountain coding scheme outperforms the benchmarks in multiple metrics. We also show the impact of packet size and the number of source packets on the proposed scheme in BER performance.