Caching in Heterogeneous Ultradense 5G Networks: A Comprehensive Cooperation Approach

Rich multimedia services have significantly increased the traffic load over mobile networks. Emerging mobile content caching techniques can efficiently relieve overloaded network traffic by caching popular contents at intermediate nodes and routers. Furthermore, stimulated by network densification, coordinated multipoint (CoMP) joint transmission (JT) techniques are expected to have a significant role in 5G networks. In this article, we present a system architecture for a cache-enabled heterogeneous ultradense network (HUDN) that consists of CoMP-integrated ultradense cells and cluster-based device-to-device (D2D) networks. We propose three cooperative caching schemes in cellular networks, D2D networks, and cross-tier networks. In the proposed schemes, caching decisions will be made by considering the content?s popularity, the device distribution, the transmission method, and the caching capability. Numerical evaluations reveal that the proposed schemes outperform existing ones in terms of delay and cache hit probability.