Error mitigation using RaptorQ codes in an experimental indoor free space optical link under the influence of turbulence

This paper is a postprint of a paper submitted to and accepted for publication in [journal] and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital LibraryIn free space optical (FSO) communications, several factors can strongly affect the link quality. Among them, one of the most important impairments that can degrade the FSO link quality and its reliability even under the clear sky conditions consists of optical turbulence. In this work, the authors investigate the generation of both weak and moderate turbulence regimes in an indoor environment to assess the FSO link quality. In particular, they show that, due to the presence of the turbulence, the link experiences both erasure errors and packet losses during transmission, and also compare the experimental statistical distribution of samples with the predicted Gamma Gamma model. Furthermore, the authors demonstrate that the application of the RaptorQ codes noticeably improves the link quality decreasing the packet error rate (PER) by about an order of magnitude, also offering in certain cases an error-free transmission with a PER of ∼10−2 at Rytov variance value of 0.5. The results show that the recovery rate increases with the redundancy, the packet length and the number of source packets, and it decreases with increasing data rates.This work was supported by the European Space Agency under grant no. 5401001020. We are very grateful to Dr. E. Armandillo for enlightening discussions. This research project also falls within the frame of COST ICT Action IC1101 - Optical Wireless Communications - An Emerging Technology (OPTICWISE). J. Perez's work is supported by Spanish MINECO Juan de la Cierva JCI-2012-14805.Pernice, R.; Parisi, A.; Ando, A.; Mangione, S.; Garbo, G.; Busacca, AC.; Perez, J.... (2015). Error mitigation using RaptorQ codes in an experimental indoor free space optical link under the influence of turbulence. IET Communications. 9(14):1800-1806. https://doi.org/10.1049/iet-com.2015.0235S18001806914Tsukamoto, K., Hashimoto, A., Aburakawa, Y., & Matsumoto, M. (2009). The case for free space. IEEE Microwave Magazine, 10(5), 84-92. doi:10.1109/mmm.2009.933086Paraskevopoulos, A., Vučić, J., Voss, S.-H., Swoboda, R., & Langer, K.-D. (2010). Optical Wireless Communication Systems in the Mb/s to Gb/s Range, Suitable for Industrial Applications. IEEE/ASME Transactions on Mechatronics, 15(4), 541-547. doi:10.1109/tmech.2010.2051814Ghassemlooy, Z., Le Minh, H., Rajbhandari, S., Perez, J., & Ijaz, M. (2012). Performance Analysis of Ethernet/Fast-Ethernet Free Space Optical Communications in a Controlled Weak Turbulence Condition. Journal of Lightwave Technology, 30(13), 2188-2194. doi:10.1109/jlt.2012.2194271Ciaramella, E., Arimoto, Y., Contestabile, G., Presi, M., D’Errico, A., Guarino, V., & Matsumoto, M. (2009). 1.28-Tb/s (32 $\times$ 40 Gb/s) Free-Space Optical WDM Transmission System. IEEE Photonics Technology Letters, 21(16), 1121-1123. doi:10.1109/lpt.2009.2021149Parca, G. (2013). Optical wireless transmission at 1.6-Tbit/s (16×100  Gbit/s) for next-generation convergent urban infrastructures. Optical Engineering, 52(11), 116102. doi:10.1117/1.oe.52.11.116102Hulea, M., Ghassemlooy, Z., Rajbhandari, S., & Tang, X. (2014). Compensating for Optical Beam Scattering and Wandering in FSO Communications. Journal of Lightwave Technology, 32(7), 1323-1328. doi:10.1109/jlt.2014.2304182Ghassemlooy, Z., Popoola, W. O., Ahmadi, V., & Leitgeb, E. (2009). MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels. Communications Infrastructure. Systems and Applications in Europe, 61-73. doi:10.1007/978-3-642-11284-3_7Garcia-Zambrana, A. (2007). Error rate performance for STBC in free-space optical communications through strong atmospheric turbulence. IEEE Communications Letters, 11(5), 390-392. doi:10.1109/lcomm.2007.061980Abou-Rjeily, C. (2011). On the Optimality of the Selection Transmit Diversity for MIMO-FSO Links with Feedback. IEEE Communications Letters, 15(6), 641-643. doi:10.1109/lcomm.2011.041411.110312García-Zambrana, A., Castillo-Vázquez, C., & Castillo-Vázquez, B. (2010). Rate-adaptive FSO links over atmospheric turbulence channels by jointly using repetition coding and silence periods. Optics Express, 18(24), 25422. doi:10.1364/oe.18.025422Andò, A., Mangione, S., Curcio, L., Stivala, S., Garbo, G., Pernice, R., & Busacca, A. C. (2013). Recovery Capabilities of Rateless Codes on Simulated Turbulent Terrestrial Free Space Optics Channel Model. International Journal of Antennas and Propagation, 2013, 1-8. doi:10.1155/2013/692915MacKay, D. J. C. (2005). Fountain codes. IEE Proceedings - Communications, 152(6), 1062. doi:10.1049/ip-com:20050237Shokrollahi, A. (2006). Raptor codes. IEEE Transactions on Information Theory, 52(6), 2551-2567. doi:10.1109/tit.2006.874390Anguita, J. A., Neifeld, M. A., Hildner, B., & Vasic, B. (2010). Rateless Coding on Experimental Temporally Correlated FSO Channels. Journal of Lightwave Technology, 28(7), 990-1002. doi:10.1109/jlt.2010.2040136Wang, N., & Cheng, J. (2010). Moment-based estimation for the shape parameters of the Gamma-Gamma atmospheric turbulence model. Optics Express, 18(12), 12824. doi:10.1364/oe.18.012824Zvanovec, S., Perez, J., Ghassemlooy, Z., Rajbhandari, S., & Libich, J. (2013). Route diversity analyses for free-space optical wireless links within turbulent scenarios. Optics Express, 21(6), 7641. doi:10.1364/oe.21.007641Pernice, R., Perez, J., Ghassemlooy, Z., Stivala, S., Cardinale, M., Curcio, L., … Parisi, A. (2015). Indoor free space optics link under the weak turbulence regime: measurements and model validation. IET Communications, 9(1), 62-70. doi:10.1049/iet-com.2014.043

Statistical analysis of RaptorQ failure probability applied to a data recovery software

In this work, we have implemented a data recovery software integrating the most recent rateless codes, i.e., RaptorQ codes. Thanks to the above-mentioned software, it is possible to recover data loss occurring on several kinds of network conditions. We have performed a statistical analysis of failure probabilities at several configurations of RaptorQ parameters. We have found a good agreement with the theoretical values of a random linear fountain code over Galois Field GF(256). Moreover, we have shown that the probability of having a certain number of failed decoded source blocks - when sending a fixed size file - follows a Poisson distribution