Cooperative Caching in Two-Layer Hierarchical Cache-aided Systems

Caching has received much attention as a promising technique to overcome high data rate and stringent latency requirements in the future wireless networks. The premise of caching technique is to prefetch most popular contents closer to end users in local cache of edge nodes, e.g., base station (BS). When a user requests a content that is available in the cache, it can be served directly without being sent from the core network. In this paper, we investigate the performance of hierarchical caching systems, in which both BS and end users are equipped with a storage memory. In particular, we propose a novel cooperative caching scheme that jointly optimizes the content placement at the BS’s and users’ caches. The proposed caching scheme is analytically shown to achieve a larger global caching gain than the reference in both uncoded – and coded caching strategies. Finally, numerical results are presented to demonstrate the effectiveness of our proposed caching algorithm. Keywords Hierarchical caching system, cooperative caching, caching gain, uncoded caching, coded caching  References [1] D. Liu, B. Chen, C. Yang, A.F. Molisch, Caching at the Wireless Edge: Design Aspects, Challenges, and Future Directions, IEEE Communications Magazine 54 (2016) 22-28. https://doi.org/10.1109/MCOM.2016.7565183.[2] T.X. Vu, S. Chatzinotas, B. Ottersten, Edge-Caching Wireless Networks: Performance Analysis and Optimization, IEEE Transactions on Wireless Communications 17 (2018) 2827-2839. https://doi.org/10.1109/TWC.2018.2803816.[3] M.A. Maddah-Ali, U. Niesen, Fundamental Limits of Caching, IEEE Transactions on Information Theory 60 (2014) 2856-2867. https://doi.org/10.1109/TIT.2014.2306938.[4] M.A. Maddah-Ali, U. Niesen, Decentralized Coded Caching Attains Order-Optimal Memory-Rate Tradeoff,  IEEE/ACM Transactions on Networking 23 (2015) 1029-1040. https://doi.org/10.1109/TNET.2014.2317316.[5] U. Niesen, M.A. Maddah-Ali, Coded Caching with Nonuniform Demands, IEEE Transactions on Information Theory 63 (2017) 1146-1158. https://doi.org/10.1109/TIT.2016.2639522.[6] Q. Yu, M.A. Maddah-Ali, A.S. Avestimehr, The exact rate-memory tradeoff for caching with uncoded prefetching, IEEE Transactions on Information Theory 64 (2018) 1281-1296. https://doi.org/10.1109/TIT.2017.2785237.[7] S.P. Shariatpanahi, H. Shah-Mansouri, B.H. Khalaj, Caching gain in interference-limited wireless networks, IET Communications 9 (2015) 1269-1277. https://doi.org/10.1049/iet-com.2014.0955.[8] N. Naderializadeh, M.A. Maddah-Ali, A.S. Avestimehr, Fundamental limits of cache-aided interference management, IEEE Transactions on Information Theory 63 (2017) 3092-3107. https://doi.org/10.1109/TIT.2017.2669942.[9] J. Hachem, U. Niesen, S. Diggavi, Energy-Efficiency Gains of Caching for Interference Channels, IEEE Communications Letters 22 (2018) 1434-1437. https://doi.org/10.1109/LCOMM.2018.2822694.[10] M.A. Maddah-Ali, U. Niesen, Cache-aided interference channels, IEEE International Symposium on Information Theory ISIT, 2015, pp. 809-813. https://doi.org/10.1109/ISIT.2015.7282567.[11] T.X. Vu, S. Chatzinotas, B. Ottersten, T.Q. Duong, Energy minimization for cache-assisted content delivery networks with wireless backhaul, IEEE Wireless Communications Letters 7 (2018) 332-335. https://doi.org/10.1109/LWC.2017.2776924.[12] S. Li, Q. Yu, M.A. Maddah-Ali, A.S. Avestimehr, Coded distributed computing: Fundamental limits and practical challenges, 50th Asilomar Conference on Signals, Systems and Computers (2016) 509-513. https://doi.org/ 10.1109/ACSSC.2016.7869092.[13] S. Li, M.A. Maddah-Ali, Q. Yu, A.S. Avestimehr, A fundamental tradeoff between computation and communication in distributed computing, IEEE Transactions on Information Theory 64 (2018) 109-128. https://doi.org/10.1109/TIT.2017.2756959.[14] S. Borst, V. Gupta, A. Walid, Distributed caching algorithms for content distribution networks, Proceedings IEEE INFOCOM. (2010) 1-9. https://doi.org/10.1109/INFCOM.2010.5461964.[15] N. Karamchandani, U. Niesen, M.A. Maddah-Ali, SN Diggavi, Hierarchical coded caching, IEEE Transactions on Information Theory 62 (2016) 3212-3229. https://doi.org/10.1109/TIT.2016.2557804.[16] S.P. Shariatpanahi, G. Caire, B. H. Khalaj, Multi-antenna coded caching, IEEE International Symposium on Information Theory ISIT, 2017, pp. 2113-2117. https://doi.org/10.1109/ISIT.2017.8006902.[17] R. Pedarsani, M.A. Maddah-Ali, U. Niesen, Online coded caching, IEEE/ACM Transactions on Networking 24 (2016) 836-845. https://doi.org/10.1109/TNET.2015.2394482.