  Coded caching is an information theoretic scheme to reduce high peak hours
traffic by partially prefetching files in the users local storage during low
peak hours. This paper considers heterogeneous decentralized caching systems
where cache of users and content library files may have distinct sizes. The
server communicates with the users through a Gaussian broadcast channel. The
main contribution of this paper is a novel modulation strategy to map the
multicast messages generated in the coded caching delivery phase to the symbols
of a signal constellation, such that users can leverage their cached content to
demodulate the desired symbols with higher reliability. For the sake of
simplicity, in this paper we focus only on uncoded modulation and
symbol-by-symbol error probability. However, our scheme in conjunction with
multilevel coded modulation can be extended to channel coding over a larger
block lengths.
