Delay Optimal Scheduling for Chunked Random Linear Network Coding Broadcast

Abstract

We study the broadcast transmission of a single file to an arbitrary number of receivers using Random Linear Network Coding (RLNC) in a network with unreliable channels. Due to the increased computational complexity of the decoding process (especially for large files) we apply chunked RLNC (i.e. RLNC is applied within non-overlapping subsets of the file). In our work we show the optimality of the Least Received (LR) batch scheduling policy (which was introduced in our prior work) with regards to the expected file transfer completion time. Furthermore, we refine some of our earlier results, namely the expected file transfer completion time of the LR policy and the minimum achievable coding window size in the case of a user defined delay constraint. Finally, we experimentally evaluate a modification of the LR policy in a more realistic system setting with reduced feedback from the receivers.