State-of-the-art in cache-aided combination networks

Caching is an effective approach to smooth out network traffic by storing some content in users' local memories during off-peak hours, which can be used to reduce the required number of transmissions during peak-traffic hours. This paper reviews recent advances on cache-aided relay networks, in particular for combination networks, which has a specific symmetric network topology. Two approaches exist for relay networks with end-user caches, depending on whether the generation of the multicast messages for the delivery phase is independent of the network topology. We review state-of-the-art schemes by categorizing them according to one of these two approaches. We also discuss their optimality (exact or to within a multiplicative factor).