Elsevier

Computer Communications

Volume 151, 1 February 2020, Pages 556-580
Computer Communications

Review
Energy aware edge computing: A survey

https://doi.org/10.1016/j.comcom.2020.01.004Get rights and content

Abstract

Edge computing is an emerging paradigm for the increasing computing and networking demands from end devices to smart things. Edge computing allows the computation to be offloaded from the cloud data centers to the network edge and edge nodes for lower latency, security and privacy preservation. Although energy efficiency in cloud data centers has been broadly investigated, energy efficiency in edge computing is largely left uninvestigated due to the complicated interactions between edge devices, edge servers, and cloud data centers. In order to achieve energy efficiency in edge computing, a systematic review on energy efficiency of edge devices, edge servers, and cloud data centers is required. In this paper, we survey the state-of-the-art research work on energy-aware edge computing, and identify related research challenges and directions, including architecture, operating system, middleware, applications services, and computation offloading.

Introduction

The advances in sensors, and wireless communication technologies promote the wide deployment of mobile devices and smart things in industrial and personal scenarios. With higher computing capability and higher storage capacity, these mobile devices and smart things can provide various kinds of services [1], such as data aggregation, real-time local data analytics, content caching and transmission relay. The devices deployed at the network edge are usually referred to as edge devices. Edge devices with more functionalities and more powerful computing capabilities are referred to as edge servers since they are closer to network edge and farther away from the cloud data centers. Edge computing can fully exploit the computing capability of edge devices and edge servers [2], [3]. Applications can be executed at the network edge closer to data sources. Processing the data at the network edge provides shorter response time and less pressure on the network bandwidth. As such, edge computing improves the user experience for time-sensitive application significantly.

In particular, mobile edge computing (MEC) is becoming a promising paradigm to provide more responsive computing services at the network edge [4], [5]. However, edge devices are usually resource-constrained with limited computing capability and power supply. In some cases edge devices are prohibited from executing applications that require a high-power supply and a large amount of data processing [6]. To this end, migrating computing tasks to nearby edge servers or cloud data centers can improve the application performance for large volume data analytics or resource-hungry computing intensive processing such as deep learning model training and inference [7]. In edge computing environment, computing tasks can be offloaded from the cloud data center to edge servers or edge devices for low latency and data privacy preservation.

In edge computing environment, both devices and servers are usually heterogeneous in terms of hardware capabilities, architectural and programming interoperability, operating system, and services stacks. Many edge devices are resource constrained in computing capability, storage capacity and network connectivity. In many edge computing scenarios increasing the energy consumption could have a negative impact on the power-constrained IoT device or edge cloud side with limited power sources. Since billions of edge devices are deployed in edge computing environment, their total energy consumptions are immense and as important as those of cloud data centers. For example, for battery powered devices or power constrained edge nodes, energy aware edge computing can extend their lifetime, provide quality of service guarantee, or increase system throughput under specific power budget. Different from energy aware computing in server systems and cloud data centers, energy awareness in edge computing involves all operations conducted along data’s whole life cycle, including data generation, transmission, aggregation, storage, processing, and etc. Therefore, energy aware computing is urged for all aspects of edge computing, including architecture, operating system, middleware, service provisioning, and computing offloading.

In edge computing, computation offloading is frequently invoked for latency minimization and Quality of Services guarantee. Specifically, in order to tradeoff among system overheads, energy consumption, and system performance, tasks may be offloaded to edge devices from the cloud data centers. However, computing offloading may lead to jitter in quality of service along with energy shifting and redistribution among different edge nodes. Nowadays, energy efficiency has become one of the most important concerns for both cloud servers and mobile devices. Though energy efficiency in cloud data centers has been thoroughly investigated, energy efficiency in edge computing is largely left uninvestigated due to the complicated interactions between edge devices, edge servers, and cloud data centers.

In this paper, we conduct a thorough survey on the energy aware edge computing. From the hardware layer to the application layer, we provide a bottom-up systematic review of the existing work on energy efficiency in edge computing. A systematic view of the survey is presented in Fig. 1.

This remainder of this paper is organized as follows. Section 2 reviews energy-aware hardware design in edge computing. We review the work on energy-aware edge architectures in Section 3 and energy-aware edge operating systems in Section 4. We discuss the energy-aware edge middleware in Section 5 and energy-aware applications and services provisioning in Section 6. Energy-aware computing offloading is surveyed in Section 7 and we conclude our paper in Section 8.

Section snippets

Energy-aware edge hardware design

Edge devices are widely deployed in various scenarios, such as smart cities, vehicles, industrial workplace, smart home, and information and communication infrastructures. However, these edge devices are resource-constrained with limited power supply, or they are equipped with lower powerful computing and storage resources for computing-intensive tasks. Hence, energy efficiency should be the primary design goal for edge devices, such as processors, sensors, edge servers, switches, and routers.

Energy-aware edge computing architecture

Energy aware architectural design is vital for edge computing although hardware level energy reduction capabilities are available in current edge devices. Architecture design may harness and integrate different level of energy aware approaches and provide functions and capabilities for energy awareness programming interface design and implementation. In this section, we survey the research work of energy-aware edge computing architecture, including memory system, networking, compiler and

Energy-aware edge OS

A typical operating system (OS) manages computer hardware, software resources, and provides common services for computer programs. With operating system, developers can build applications without thinking too much about the device underneath and in most cases, applications take advantage of services and APIs available in the OS without having to deal directly with hardware resources and even network connectivity. With the advance in computer technology, smaller, lighter, and faster computing

Energy-aware edge middleware

Middleware provides abstraction of underlying resources to upper service applications. In order to provide energy efficient resource transparency and interpretation, edge middleware must have elaborate system design on networking, storage, and computing. For example, it is usually assumed that in edge computing scenario, IoT services are depending on always-connected networking. However, the always-connected approach can sometimes generate boatloads of data and not all of it is necessary at the

Energy aware edge services & applications

In this section, we focus on the topic of energy-aware edge devices and applications. The related work of energy awareness in edge devices and applications is listed in Fig. 7. According to Fig. 7, we provide Table 7 for a reference to the existing work.

Energy aware computing offloading

Computing offloading from the edge to the cloud is a promising technique that saves battery while improving the computing capabilities of edge devices [214]. However, it is not always energy efficient when applications are offloaded to the cloud. Since the energy efficiencies of mobile devices, edge servers, and cloud servers are different, the energy consumption of each type of device/server varies and depends on the type of device/server where the tasks are executed. An inefficient offloading

Conclusions and future work

Edge computing is an emerging paradigm to meet the ever-increasing computing and communication demands from billions of edge devices. Edge computing is promising for various application scenarios due to its less network bandwidth usage and thus less data center side processing pressure, as well as enhanced service responsiveness and data privacy protection. Edge Computing is becoming feasible to handle the data deluge occurring in the network edge to gain insights that assist in real-time

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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    This work is supported by Natural Science Foundation of China (No. 61972118, No. 61972358, and No. 61572163), and Key Research and Development Program of Zhejiang Province, China (No. 2018C01098 and No. 2019C01059).

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