Robust LT codes with alternating feedback

In this paper, we propose robust LT codes with alternating feedback (LT-AF codes), which lightly utilize the feedback channel and surpass the performance of existing LT codes with feedback. In LT-AF codes, we consider a loss prone feedback channel for the first time and propose the encoder to generate degree-one output symbols (encoded symbols) only in acknowledgement to the reception of feedbacks. Therefore, LT-AF codes become robust against feedback losses meaning that their performance does not deteriorate even at high feedback loss rates in contrast to previous work. To realize this, we design a new and parameterless coding degree distribution for LT-AF coding based on Ideal-Soliton (IS) distribution of LT codes.In addition, we design a new feedback scheme and use it in conjunction with an existing feedback method. Therefore, in LT-AF codes the decoder can alternate between either types of feedback based on its status. To generate our new type of feedback, we propose three novel algorithms to analyze the buffered output symbols at the decoder. We will show that LT-AF codes require a significantly lower coding overhead for a successful decoding.