ISIT 2020, IEEE International Symposium on Information Theory, 21-26 June 2020, Los Angeles, California, USA (Virtual Conference)
This work considers the cache-aided multiple-input single-output broadcast channel (MISO BC) where an L-antenna transmitter serves K receiving users, each assisted by one of < K caches with normalized capacity. For this setting it was known that in the range of L 2 [K=;K ], one can achieve a Degrees-of-Freedom (DoF) performance of L + K. This very restrictive constraint that L K excluded sharedcache settings with a large number of antennas from achieving the maximum DoF; for the more realistic regime of L > K, all existing coded caching schemes suffer substantially reduced caching or multiplexing gains. Our work provides a novel coded caching scheme that achieves the exact best known, near optimal, DoF L+K, and does so even if L > K, thus covering an important hole in identifying the optimal performance for the multi-antenna shared-cache problem. Therefore, our work reveals that shared-cache systems with many transmit antennas can also enjoy both full multiplexing gains (L) as well as full caching gains (K) despite the sharing of the caches. A side benefit of this scheme is its applicability in multi-antenna settings with dedicated users caches, where it can offer the advantage of reducing the subpacketization without sacrificing the DoF performance.
Systèmes de Communication
© 2020 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.