ABSTRACT
Multicellular heterogeneous networks serve the demands of high-speed Internet services, streaming audio/video applications, social networking applications, device-to-device communication systems, and machine-to-machine communication systems. Heterogeneous networks (HetNets) consist of high-power nodes (such as macrocells, microcells, remote relay head nodes [RRHNs]) and low-power nodes (such as picocells and femtocells). A macro base station (MaBS) covers the network area but cannot reach the demands of user nodes in dense traffic zones. Hence, pico base stations (PiBSs) and femto base stations (FeBSs) that cover a few meters resolve the issue of connectivity and serve the user nodes in dense traffic areas and hotspot regions of the network. Dense deployment of picocells and femtocells in hotspot zones cause signal interference that further leads to the drop in performance gain. Techniques such as beamforming, carrier aggregation, coordinated multipoint transmission (CoMP) and sub-frame scheduling increase the spectral efficiency and achieve high data transfer rates in HetNets. Orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA) implemented with CoMP and enhanced intercell interference coordination (eICIC) reduce the effects of interference in small-cell HetNets. Cloud-based radio access network (C-RAN) [1] is a fronthaul network comprising multiple remote relay head nodes connected to a baseband unit located near the user nodes. C-RAN implements a centralized approach for resource allocation and CoMP-based transmissions to minimize the ICI effect.
