Delivery phase in cache-based wireless networks with modified LT codes

Abstract

Caching has emerged as an efficient technique to reduce delivery latency and network congestion. The focus of this paper is on content delivery in the caching-based wireless systems. In view of the fact that in such systems, users store fractional of popular contents during off-peak hours, we propose a modified version of the Luby Transform (MLT) encoding for the delivery phase to take the advantage of channel coding. The novelty of our proposed MLT encoding lies in employing the user’s partial information to create an appropriate degree distribution. To evaluate our proposed scheme, this study considers a realistic channel model inspired by the Gilbert-Elliott channel including the erasure mode and a binary symmetric channel model. The effectiveness of our MLT encoding is analyzed by the average degree and the number of encoding symbol. A comprehensive simulation evaluation is performed which shows that MLT encoding outperforms conventional LT coding in terms of the required number of encoding symbols and demonstrates a better performance on the recovered symbols. In particular, the MLT encoding, compared to the conventional LT encoding, reduces the amount of required symbols to recover the original file for at least 20%, when the user stored more than half a file.