Resolving a feedback bottleneck of multi-antenna coded caching

Lampiris, Eleftherios; Elia, Petros
IEEE Transactions on Information Theory, 27 December 2021

 The work here makes substantial progress towards resolving the well known feedback bottleneck of multi-antenna coded caching, by introducing a fundamentally new algorithm that completely untangles caching gains from feedback costs. In the context of the K-user MISO broadcast channel with cacheaided receivers and an L-antenna transmitter, the algorithm achieves full multiplexing gains and unbounded near-optimal caching gains at the mere CSIT/CSIR costs associated to achieving multiplexing gains only. While prior state-of-art required feedback costs that scaled with K, the new algorithm requires only L uplink/downlink feedback acquisition slots, irrespective of how large the achieved caching gain is, and thus irrespective of how many users are served at a time. In the end, the result solidifies the role of coded caching as a method for reducing feedback requirements in multi-antenna environments. 

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