MS Thesis Defense: Yuezhou Liu

MS Thesis Defense: Optimizations of Caching Networks: Fairness and Application to Mobile Networks

Yuezhou Liu

Location: Zoom Link

Abstract: In-network caching is playing a more and more important role in today’s network architectures, because of the explosive growth of data traffic due to the proliferation of mobile devices and demands for high-volume media content, as well as the development of low-latency applications, such as VR/AR and cloud gaming. The replication of popular contents in the caches that located closer to end users than central servers, can significantly reduce backbone traffic, benefit request latency, and balance the load of central servers. In this thesis, we study two problems in the field of network caching. In the first part, we consider fair caching policies in caching networks with arbitrary topology. We introduce a utility maximization framework to find a caching decision that reduces aggregate expected request routing cost in the network while taking fairness issues into consideration. The utility maximization problem is NP-hard, and we propose two efficient approximation algorithms to solve it. In the second part, we study how caching may affect user association in mobile networks. We jointly optimize the user association decision and caching at both base stations (BSs) and gateways (GWs). The resulting problem is also NP-hard. We propose a polynomial-time algorithm based on concave approximation and pipage rounding that produces a solution within a constant factor of 1-1/e from the optimal. Simulation results show that the proposed algorithm outperforms schemes that combine cache-independent user association methods with traditional caching strategies (e.g., LRU) in terms of minimizing the aggregate expected routing cost and backhaul traffic while achieving a high data sum rate in the access network.