Preference-Aware Caching and Cooperative Coded Multicasting Design for Wireless Backhaul Networks

Abstract

The joint considering of caching and coded multicasting can significantly improve caching gain, which has become a promising approach to address the explosive growth of wireless traffic demand. In this paper, the design of caching placement and coded multicasting for wireless backhaul networks is explored under heterogeneous file preferences, where the file preference of each small base station (BS) is assumed to be aware at the macro BS. To address the heterogeneous file preferences, a group-based caching and cooperative coded multicasting scheme is developed in this paper. By utilizing the spectral clustering method, the small BSs are first clustered into different groups with similar file preferences. Moreover, a cooperative caching strategy with symmetric file division is designed for each group, where the suboptimal caching proportion of the most popular files is achieved by an approximation analysis. By utilizing the group-based caching structure, an efficient greedy-based two-level cooperative coded multicasting algorithm is then developed. The proposed algorithm not only utilizes the coded multicasting opportunities within each group, but also explores the cooperative coding opportunities among groups. The effectiveness of our proposed scheme is verified by simulation results, which show that our proposed scheme can significantly reduce the traffic load compared to the existing schemes.