Recent Advances of Heterogenous RadioAccess Networks: A Survey

Abstract

As a promising paradigm to provide high spectral efficiency and energy efficiency, heterogenous radio access networks (HetNets) have attracted a lot of attention from both academia and industry. This paper presents a comprehensive survey of the recent advances in HetNets, including system architecture evolutions, key techniques, and open issues. The system architectures introduced include conventional HetNets, HetNets with cloud computing, and HetNets with fog computing. In addition, a novel performance metric, together with network self-organization and access slicing, is elaborated, which can help realize a cost-efficient HetNet. Moreover, the other state-of-the-art key techniques in HetNets are surveyed, including nonorthogonal multiple access, interference suppression, and channel estimation in the physical layer, the radio resource allocation in the medium access control layer, and clustering in the network layer. Given the extensiveness of the research area, future research opportunities are identified, which are related to access slicing, HetNets driven by deep learning, and so on.

A Survey on Applications of Deep Learning in Cloud Radio Access Network

“…Apart from C-RAN, other studies have reviewed the H-CRAN architecture, describing the system architecture and recent advances. The authors in [92] presented a review of the evolution of the system architecture, key techniques, and open issues in heterogeneous networks. They also mentioned H-CRAN and fog RAN.…”

Flying to the Clouds: The Evolution of the 5G Radio Access Networks

“…As the volume of end users and complexity of the services offered by the operators has increased, new drawback in conventional D-RAN deployments emerged. For instance, average spectral efficiency gains of only 20% were observed in RAN deployments (Sun and Peng 2018). As a result, Cloud RANs (C-RANs) have emerged as a centralised solution, moving the BS functionalities to the cloud in order to optimise the resources and improve energy efficiency (Wu et al 2015;Peng et al 2015a, b).…”

“…The constrained capacity of front-haul links is also a problem. This results in a significant negative impact on both energy efficiency and spectral efficiency (Sun and Peng 2018). Two proposed innovation to address these issues are heterogeneous C-RAN (H-CRAN) and fog RAN (F-RAN).…”

“…HPNs, such as macro cell base stations (MBS), are in charge of wide network coverage. LPNs, such as small cell base stations (SBS), are low powered nodes densely deployed, offering high data rates in hot spots and seamless mobility, referring to the SBSs (Sun and Peng 2018). To manage complexity and for efficiency and costeffectiveness, HetNets support self-organisation, allowing cooperation between the base stations to optimally coordinate their resources.…”

“…The BBU is responsible for coordination between HPNs and RRHs to mitigate inter-tier interference. The BBU pool is also responsible for important upper layer functions (Sun and Peng 2018;Ali et al 2017).…”