Softwarization of Mobile Network Functions towards Agile and Energy Efficient 5G Architectures: A Survey <s> 2.5. <s> Internet hosting centers serve multiple service sites from a common hardware base. This paper presents the design and implementation of an architecture for resource management in a hosting center operating system, with an emphasis on energy as a driving resource management issue for large server clusters. The goals are to provision server resources for co-hosted services in a way that automatically adapts to offered load, improve the energy efficiency of server clusters by dynamically resizing the active server set, and respond to power supply disruptions or thermal events by degrading service in accordance with negotiated Service Level Agreements (SLAs).Our system is based on an economic approach to managing shared server resources, in which services "bid" for resources as a function of delivered performance. The system continuously monitors load and plans resource allotments by estimating the value of their effects on service performance. A greedy resource allocation algorithm adjusts resource prices to balance supply and demand, allocating resources to their most efficient use. A reconfigurable server switching infrastructure directs request traffic to the servers assigned to each service. Experimental results from a prototype confirm that the system adapts to offered load and resource availability, and can reduce server energy usage by 29% or more for a typical Web workload. <s> BIB001 </s> Softwarization of Mobile Network Functions towards Agile and Energy Efficient 5G Architectures: A Survey <s> 2.5. <s> Power management has become increasingly necessary in large-scale datacenters to address costs and limitations in cooling or power delivery. This paper explores how to integrate power management mechanisms and policies with the virtualization technologies being actively deployed in these environments. The goals of the proposed VirtualPower approach to online power management are (i) to support the isolated and independent operation assumed by guest virtual machines (VMs) running on virtualized platforms and (ii) to make it possible to control and globally coordinate the effects of the diverse power management policies applied by these VMs to virtualized resources. To attain these goals, VirtualPower extends to guest VMs `soft' versions of the hardware power states for which their policies are designed. The resulting technical challenge is to appropriately map VM-level updates made to soft power states to actual changes in the states or in the allocation of underlying virtualized hardware. An implementation of VirtualPower Management (VPM) for the Xen hypervisor addresses this challenge by provision of multiple system-level abstractions including VPM states, channels, mechanisms, and rules. Experimental evaluations on modern multicore platforms highlight resulting improvements in online power management capabilities, including minimization of power consumption with little or no performance penalties and the ability to throttle power consumption while still meeting application requirements. Finally, coordination of online methods for server consolidation with VPM management techniques in heterogeneous server systems is shown to provide up to 34% improvements in power consumption. <s> BIB002 </s> Softwarization of Mobile Network Functions towards Agile and Energy Efficient 5G Architectures: A Survey <s> 2.5. <s> Due to the enormous energy consumption and associated environmental concerns, data centers have been increasingly pressured to reduce long-term net carbon footprint to zero, i.e., carbon neutrality. In this paper, we propose an online algorithm, called COCA (optimizing for COst minimization and CArbon neutrality), for minimizing data center operational cost while satisfying carbon neutrality without long-term future information. Unlike the existing research, COCA enables distributed server-level resource management: each server autonomously adjusts its processing speed and optimally decides the amount of workloads to process. We prove that COCA achieves a close-to-minimum operational cost (incorporating both electricity and delay costs) compared to the optimal algorithm with future information, while bounding the potential violation of carbon neutrality. We also perform trace-based simulation studies to complement the analysis, and the results show that COCA reduces cost by more than 25% (compared to state of the art) while resulting in a smaller carbon footprint. <s> BIB003 </s> Softwarization of Mobile Network Functions towards Agile and Energy Efficient 5G Architectures: A Survey <s> 2.5. <s> As mobile network users look forward to the connectivity speeds of 5G networks, service providers are facing challenges in complying with connectivity demands without substantial financial investments. Network function virtualization (NFV) is introduced as a new methodology that offers a way out of this bottleneck. NFV is poised to change the core structure of telecommunications infrastructure to be more cost-efficient. In this article, we introduce an NFV framework, and discuss the challenges and requirements of its use in mobile networks. In particular, an NFV framework in the virtual environment is proposed. Moreover, in order to reduce signaling traffic and achieve better performance, this article proposes a criterion to bundle multiple functions of a virtualized evolved packet core in a single physical device or a group of adjacent devices. The analysis shows that the proposed grouping can reduce the network control traffic by 70 percent. <s> BIB004 </s> Softwarization of Mobile Network Functions towards Agile and Energy Efficient 5G Architectures: A Survey <s> 2.5. <s> With ever growing mobile Internet and the explosion of its applications, users are experiencing abundant services from different content providers via different network service providers in the heterogeneous network. The information-centric network (ICN) advocates getting rid of the current host-centric network protocol because information dissemination rather than end-to-end communication contributes to the majority of today's network traffic. Furthermore, it is better for network entities to converge as a whole in order to take advantage of open, scalable, and smart traffic transmission. The cloud radio access network is one of the emerging architecture evolutions on the wireless side for easier infrastructure deployment and network management. Therefore, when the information-centric network meets the C-RAN in the Het-Net, it is worthwhile and consequential to integrate ICN protocol with C-RAN architecture to achieve more efficient communication and information management. Moreover, SDN has been recognized as another promising architecture evolution to achieve the flexibility and reconfigurability of dense HetNets; its inherent advantage lies in global uniform control of the wired network. Thus, any of ICN, C-RAN and SDN is the complementary to the others. In this article, we contribute to a fresh proposal for and elaboration of the integration of the ICN, CRAN, and SDN for the HetNet to achieve a win-win situation. The vision of the proposed system is demonstrated, followed by the advantages and challenges. We further present a hybrid system in a large-scale wireless heterogeneous campus network. <s> BIB005 </s> Softwarization of Mobile Network Functions towards Agile and Energy Efficient 5G Architectures: A Survey <s> 2.5. <s> Merging Mobile Edge Computing (MEC), which is an emerging paradigm to meet the increasing computation demands from mobile devices, with the dense deployment of Base Stations (BSs), is foreseen as a key step towards the next generation mobile networks. However, new challenges arise for designing energy efficient networks since radio access resources and computing resources of BSs have to be jointly managed, and yet they are complexly coupled with traffic in both spatial and temporal domains. In this paper, we address the challenge of incorporating MEC into dense cellular networks, and propose an efficient online algorithm, called ENGINE (ENerGy constrained offloadINg and slEeping) which makes joint computation offloading and BS sleeping decisions in order to maximize the quality of service while keeping the energy consumption low. Our algorithm leverages Lyapunov optimization technique, works online and achieves a close-to-optimal performance without using future information. Our simulation results show that our algorithm can effectively reduce energy consumption while guaranteeing quality of service for users. <s> BIB006
Summary. Different strategies have been employed in the design of the afore-discussed softwarized EPC architectural proposals, as we summarize in Table 1 . The main driving force behind softwarization resides in the creation of more flexible, fully reprogrammable networks, which are expected to better handle the diverse and high volume mobile traffic that is foreseen in future networks. The architectural proposals that were investigated so far involve grouping the virtualized EPC network functions BIB004 BIB005  and using NFV  34,  techniques for the EPC cloud   . Furthermore, it is shown that network management can be facilitated by the logical instantiation of a network, referred to as network slice. This allows a complete separation of network portions, which can be specialized to different purposes. Typical network slices consist of integrated SGW and PGW and the MME as proposed in    . With the emergence of MEC, virtualized EPC NFs can be deployed in close proximity to the BSs and this makes it possible to deliver services within a short space of time. Recently, many delay sensitive applications are emerging, and this has resulted in an increase in computation demand, which exceeds what mobile devices can deliver. Therefore, application-aware cell performance optimization for each device in real time is desirable, as this can improve the customer's QoE. MEC has emerged to enable data processing locally, at the network edge, and edge devices are empowered with computing and storage capabilities to serve user requests by significantly reducing the transmission latency, as they are placed in proximity of the end users. While many algorithms are being proposed, a considerable amount of research still has to be carried out and MEC optimization strategies need to be further investigated, compared, and experimented in real systems. In Table 2 , we provide a summary of the strategies proposed for handling MEC optimization problems. In [41, 43, 46-48, 52, 54, 58] different strategies have been proposed towards offloading decisions by taking into account different constraints. The numerical results in these papers all demonstrate that MEC can help optimize the energy efficiency of future mobile networks. The proposed EPC architectural designs exhibit some similarities regarding energy efficiency (EE) improvements for future networks. The shared similarities relate to enabling sleep modes at low traffic periods BIB005 BIB006 and dynamic scaling of resources within the virtualized domain  BIB002 BIB001 BIB003 . In the architecture of Section 2.1, through content caching BIB005 , at RAN and EPC, EE can be improved as content transmission and delay, bandwidth usage can be reduced, and in the architecture of Section 2.2 dynamic scaling of resources can yield improved energy savings  . The lack of slice manager in the network slicing architecture (Section 2.3) as observed in   results in less efficient resource utilization, and if present, efficient resource management can be achieved over the shared infrastructure as unused resources can be disabled, thus improving EE in virtualized platforms. Lastly, in Section 2.4, the combination of soft BIB002 and hard BIB001 scaling can improve the EE, while at the same time using sleeping modes and cooperation can 