Research On Distributed Fountain Codes

With the development of telecommunication and Internet technology, networks is be-coming large scale. Multimedia businesses with bulk data such as HD video and image are emerging, and also the multicast and broadcast technology is applied widely. Fountain codes are designed to distribute bulk data in multicast or broadcast scenarios reliably. As fountain codes have low codec complexity and don't need any feedback channels or chan-nel estimation to ensure the reliable data transmission, they have attracted more attention from both industry and academic.Since the coding of LT codes is quite simple and the decoding complexity is quite low, this paper focuses on LT codes. We first consider the design of the degree distribution, and improve the original robust soliton distribution with iLT codes. Then a packet-centric ap-proach to distributed iLT coding is presented. Each data packet finds several other distinct packets to encode independently and proactively. As the encoding process XORs some data packets approximately at random, data gathering is realized at the same time. A new energy efficient data gathering method based on distributed fountain coding is proposed. The new scheme reduces inter-communication, and accelerates the data gathering in the whole wireless sensor network.Finally, the paper studies the effective combination between distributed fountain codes and opportunistic network coding. Comprehensive explanation about the algorithm is giv-en. In hierarchical networks, the source node broadcasts data to receivers over sender nodes and multi-layer relay nodes. On the other hand, relay nodes combine weaken iLT coding and opportunistic network coding, finishing routing and coding in the meantime. Simu-lation results show that in this way not only network throughput increases, but also the overhead decreases. Furthermore, intermediate performance is improved for decoders. The new coding scheme maintains the reliable and effective data transmission.