Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks

Soaring capacity and coverage demands dictate that future cellular networks need to soon migrate towards ultra-dense networks. However, network densification comes with a host of challenges that include compromised energy efficiency, complex interference management, cumbersome mobility management, burdensome signaling overheads and higher backhaul costs. Interestingly, most of the problems, that beleaguer network densification, stem from legacy networks' one common feature i.e., tight coupling between the control and data planes regardless of their degree of heterogeneity and cell density. Consequently, in wake of 5G, control and data planes separation architecture (SARC) has recently been conceived as a promising paradigm that has potential to address most of aforementioned challenges. In this article, we review various proposals that have been presented in literature so far to enable SARC. More specifically, we analyze how and to what degree various SARC proposals address the four main challenges in network densification namely: energy efficiency, system level capacity maximization, interference management and mobility management. We then focus on two salient features of future cellular networks that have not yet been adapted in legacy networks at wide scale and thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and device-to-device (D2D) communications. After providing necessary background on CoMP and D2D, we analyze how SARC can particularly act as a major enabler for CoMP and D2D in context of 5G. This article thus serves as both a tutorial as well as an up to date survey on SARC, CoMP and D2D. Most importantly, the article provides an extensive outlook of challenges and opportunities that lie at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201

Towards 5G Cellular: Understanding 3D In-Building Single Band and Multi-band Small Cells with Control/User-plane Coupled and Separation Architectures with a Novel Resource Reuse Approach

In this paper, we present numerous small cell base station, i.e. femtocell base station (FCBS), with control-/user-plane coupled and separation architectures based on the number of transceivers and operating frequency bands to serve control-/user-plane traffic. A single transceiver enabled FCBS can operate at either a co-channel microwave of the overlaid macrocell or a millimeter wave band. For multiple transceivers, dual transceivers are considered operating at both bands. FCBSs are deployed in a number of buildings with each floor modeled as 5×5 square-grid apartments. The co-channel interference with FCBSs is avoided using enhanced intercell interference coordination techniques. We propose a static frequency reuse approach and develop an algorithm by avoiding adjacent channel interferences from reusing frequencies in FCBSs. We also develop a resource scheduling algorithm for FCBSs with CUCA and CUSA to evaluate system level performances with a multi-tier network. It is found that a single transceiver co-channel microwave enabled FCBS with CUCA provides the worse, whereas a single or dual transceivers millimeter wave enabled FCBS with CUSA provides the best overall system capacity and FCBSs’ energy efficiency performances. Besides, we show the outperformances of the proposed resource reuse approach over an existing approach in literature in terms of system capacity and fairness among FCBSs with CUCA. Finally, we point out the applicability of a multi-band enabled FCBS and several features and issues of FCBSs with CUCA and CUSA.In this paper, we present numerous small cell base station, i.e. femtocell base station (FCBS), with control-/user-plane coupled and separation architectures based on the number of transceivers and operating frequency bands to serve control-/user-plane traffic. A single transceiver enabled FCBS can operate at either a co-channel microwave of the overlaid macrocell or a millimeter wave band. For multiple transceivers, dual transceivers are considered operating at both bands. FCBSs are deployed in a number of buildings with each floor modeled as 5 by 5 square-grid apartments. The co-channel interference with FCBSs is avoided using enhanced intercell interference coordination techniques. We propose a static frequency reuse approach and develop an algorithm by avoiding adjacent channel interferences from reusing frequencies in FCBSs. We also develop a resource scheduling algorithm for FCBSs with CUCA and CUSA to evaluate system level performances with a multi-tier network. It is found that a single transceiver co-channel microwave enabled FCBS with CUCA provides the worse, whereas a single or dual transceivers millimeter wave enabled FCBS with CUSA provides the best overall system capacity and FCBSs' energy efficiency performances. Besides, we show the outperformances of the proposed resource reuse approach over an existing approach in literature in terms of system capacity and fairness among FCBSs with CUCA. Finally, we point out the applicability of a multi-band enabled FCBS and several features and issues of FCBSs with CUCA and CUSA

Energy sustainable paradigms and methods for future mobile networks: A survey

In this survey, we discuss the role of energy in the design of future mobile networks and, in particular, we advocate and elaborate on the use of energy harvesting (EH) hardware as a means to decrease the environmental footprint of 5G technology. To take full advantage of the harvested (renewable) energy, while still meeting the quality of service required by dense 5G deployments, suitable management techniques are here reviewed, highlighting the open issues that are still to be solved to provide eco-friendly and cost-effective mobile architectures. Several solutions have recently been proposed to tackle capacity, coverage and efficiency problems, including: C-RAN, Software Defined Networking (SDN) and fog computing, among others. However, these are not explicitly tailored to increase the energy efficiency of networks featuring renewable energy sources, and have the following limitations: (i) their energy savings are in many cases still insufficient and (ii) they do not consider network elements possessing energy harvesting capabilities. In this paper, we systematically review existing energy sustainable paradigms and methods to address points (i) and (ii), discussing how these can be exploited to obtain highly efficient, energy self-sufficient and high capacity networks. Several open issues have emerged from our review, ranging from the need for accurate energy, transmission and consumption models, to the lack of accurate data traffic profiles, to the use of power transfer, energy cooperation and energy trading techniques. These challenges are here discussed along with some research directions to follow for achieving sustainable 5G systems.Comment: Accepted by Elsevier Computer Communications, 21 pages, 9 figure

Cognition-inspired 5G cellular networks: a review and the road ahead

Despite the evolution of cellular networks, spectrum scarcity and the lack of intelligent and autonomous capabilities remain a cause for concern. These problems have resulted in low network capacity, high signaling overhead, inefficient data forwarding, and low scalability, which are expected to persist as the stumbling blocks to deploy, support and scale next-generation applications, including smart city and virtual reality. Fifth-generation (5G) cellular networking, along with its salient operational characteristics - including the cognitive and cooperative capabilities, network virtualization, and traffic offload - can address these limitations to cater to future scenarios characterized by highly heterogeneous, ultra-dense, and highly variable environments. Cognitive radio (CR) and cognition cycle (CC) are key enabling technologies for 5G. CR enables nodes to explore and use underutilized licensed channels; while CC has been embedded in CR nodes to learn new knowledge and adapt to network dynamics. CR and CC have brought advantages to a cognition-inspired 5G cellular network, including addressing the spectrum scarcity problem, promoting interoperation among heterogeneous entities, and providing intelligence and autonomous capabilities to support 5G core operations, such as smart beamforming. In this paper, we present the attributes of 5G and existing state of the art focusing on how CR and CC have been adopted in 5G to provide spectral efficiency, energy efficiency, improved quality of service and experience, and cost efficiency. This main contribution of this paper is to complement recent work by focusing on the networking aspect of CR and CC applied to 5G due to the urgent need to investigate, as well as to further enhance, CR and CC as core mechanisms to support 5G. This paper is aspired to establish a foundation and to spark new research interest in this topic. Open research opportunities and platform implementation are also presented to stimulate new research initiatives in this exciting area