Degrees of Freedom in Cached MIMO Interference Networks With Asynchronous User Requests

Abstract

In this paper, we study the average sum DoF of cached interference networks over random user requests. First, we derive a closed-form average sum DoF upper bound of the cached interference channels over all possible caching and transmission strategies. Then, we propose an online cache content placement algorithm to maximize the achievable average sum DoF without explicit knowledge of the popularity of the content files. We show that the gap between the DoF upper bound and an achievable DoF is small for some typical scenarios. Moreover, we quantify the DoF gain due to caching with respect to some important system parameters. We show that large DoF gain over interference network without cache is possible even if the number of files $L\rightarrow \infty$ . Both simulation and analysis indicate that the proposed scheme has significant gains over various baselines.