LT Network Codes

Network coding has been successfully applied in large-scale content dissemination systems. While network codes provide optimal throughput, its current forms suffer from a high decoding complexity. This is an issue when applied to systems composed of nodes with low processing capabilities, such as sensor networks. In this paper, we propose a novel network coding approach based on LT codes, initially introduced in the context of erasure coding. Our coding scheme, called LTNC, fully benefits from the low complexity of belief propagation decoding. Yet, such decoding schemes are extremely sensitive to statistical properties of the code. Maintaining such properties in a fully decentralized way with only a subset of encoded data is challenging. This is precisely what the recoding algorithms of LTNC achieve. We evaluate LTNC against random linear network codes in an epidemic content-dissemination application. Results show that LTNC increases communication overhead (20%) and convergence time (30%) but greatly reduces the decoding complexity (99%) when compared to random linear network codes. In addition, LTNC consistently outperforms dissemination protocols without codes, thus preserving the benefit of coding.