Caching deployment algorithm based on user preference in device-to-device networks

In cache enabled D2D communication networks, the cache space in a mobile terminal is relatively small compared with the huge amounts of multimedia contents. As such, a strategy for caching the diverse contents in a multiple cache-enabled mobile terminals, namely caching deployment, will have a substantial impact to network performance. In this paper, a user preference aware caching deployment algorithm is proposed for D2D caching networks. Firstly, based on the concept of the user preference, the definition of user interest similarity is given, in which it can be used to evaluate the similarity of user preferences. Then a content cache utility of a mobile terminal is defined by taking the communication coverage of this mobile terminal and the user interest similarity of its adjacent mobile terminals into consideration. The logarithmic utility maximization problem for caching deployment is formulated. Subsequently, we relax the logarithmic utility maximization problem, and obtain a low complexity near-optimal solution via dual decomposition method. The convergence of the proposed caching deployment algorithm is validated by simulation results. Compared with the existing caching placement methods, the proposed algorithm can achieve significant improvement on cache hit ratio, content access delay and traffic offloading gain