Evict Early, Decode Efficiently: Lightweight Decoding Strategies for Low-Delay Sliding Window RLNC

Abstract

Random Linear Network Coding (RLNC), and in particular Sliding Window RLNC (SW-RLNC), is a promising approach for reliable, low-latency communication in dynamic environments such as 6G and non-terrestrial networks. While prior work has largely focused on encoder-side parameter tuning, such as the code rate and coding window size, decoder-side design remains comparatively underexplored despite its direct impact on end-to-end performance. This paper addresses decoding window management, namely the policies governing window-boundary updates, removal of obsolete packets, and delivery of recovered packets to upper layers, and shows that these policies critically shape the trade-off between computational complexity and decoding performance, particularly in-order delivery delay. We derive sufficient conditions under which packets can be safely removed from the decoding window without compromising decodability or violating in-order delivery guarantees, and, building on these conditions, propose two lightweight decoding window management schemes. Through extensive simulation-based evaluation across a range of channel conditions and code rates, we show that both schemes preserve decoding efficiency while substantially reducing decoding complexity, and that one additionally achieves a marked reduction in in-order delivery delay. These results establish decoding window management as a key design dimension for practical SW-RLNC systems.