Coverage and Rate Analysis in Heterogeneous Cloud Radio Access Networks With Device-to-Device Communication

The implementation of heterogeneous cloud radio access network (H-CRAN) architecture is faced with practical challenges, such as the capacity and time-delay limitations of the fronthaul links. This paper considers the use of device-to-device (D2D) communication to offload the remote radio heads (RRHs) located in the coverage region of high-power nodes (HPNs). We propose an H-CRAN with non-uniformly deployed D2D communication, in which D2D links are only utilized outside a specified distance from any HPN. Based on the analytical framework provided in this paper, the coverage and the average ergodic rate of a typical user equipment (UE) are characterized. Through defining the exclusion area appropriately, the proposed non-uniform D2D deployment can achieve performance improvement compared with uniform D2D deployment. In addition, to account for the capacity constraint of fronthaul, we characterize the average traffic delivery latency experience by a typical UE when served by RRHs as a quality-of-service metric. Our results show that for a lower fronthaul capacity regime, the proposed non-uniform D2D deployment achieves lower average traffic delivery latency compared with both the uniform D2D deployment and the pure H-CRAN scenarios.