Title: Cooperative Multi-Sender Index Coding,
Abstract: In this paper, we propose a new coding scheme and establish new bounds on the
capacity region for the multi-sender unicast index-coding problem. We revisit
existing partitioned Distributed Composite Coding (DCC) proposed by Sadeghi et
al. and identify its limitations in the implementation of multi-sender
composite coding and in the strategy of sender partitioning. We then propose
two new coding components to overcome these limitations and develop a
multi-sender Cooperative Composite Coding (CCC). We show that CCC can strictly
improve upon partitioned DCC, and is the key to achieve optimality for a number
of index-coding instances. The usefulness of CCC and its special cases is
illuminated via non-trivial examples, and the capacity region is established
for each example. Comparisons between CCC and other non-cooperative schemes in
recent works are also provided to further demonstrate the advantage of CCC.