Essay: Mobile Cloud Computing: Applications and Research Issues

Abstract’ Together with an explosive growth of the mobile applications and emerging of cloud computing concept, mobile cloud computing (MCC) has been introduced to be a potential technology for mobile services. MCC integrates the cloud computing into the mobile environment and overcomes obstacles related to the performance (e.g., battery life, storage, and bandwidth), environment (e.g., heterogeneity, scalability, and availability), and security (e.g., reliability and privacy) discussed in mobile computing. This paper gives a survey of MCC, which helps general readers have an overview of the MCC including the definition, architecture, and applications. The issues, existing solutions, and approaches are presented.
In addition, the future research directions of MCC are discussed.
1. INTRODUCTION
Mobile devices (e.g., smartphone and tablet PC) are increasingly becoming an essential part of human life as the most effective and convenient communication tools not bounded by time and place. Mobile users accumulate rich experience of various services from mobile applications (e.g., iPhone apps and Google apps), which run on the devices and/or on remote servers via wireless networks. The rapid progress of mobile computing (MC) [1] becomes
a powerful trend in the development of IT technology as well as commerce and industry fields.
However, with mobility comes its inherent problems such as resource scarceness, finite energy and low connectivity as outlined by Satyanarayanan in [2]. These pose the problem of executing many useful programs that could aid the user and create a pervasive
environment. According to Tim O’Reilly ‘the future belongs to services that respond in real time to information provided either by their users or by nonhuman sensors’ [3]. Real time applications are just one type of mobile applications that demand high levels of responsiveness, that in turn, demand intensive computing resources.
Some mobile applications, such as location based social networking, process and make use of the phone’s various sensor data. However, extensive use of sensors, such as obtaining a GPS reading, is expensive in terms of energy and this limits the mobile phone in providing the user a better service through its embedded sensors. Furthermore, consider applications that require extensive processing ‘ image processing for video games, speech synthesis, natural
language processing, augmented reality, wearable computing’ all these demand high computational capacities thus restricting the developers in implementing applications for mobile phones.
In recent years, this problem has been addressed by researchers though cloud computing.
Cloud computing can be defined as the aggregation of computing as a utility and software as a service [4] where the applications are delivered as services over the Internet and the hardware and systems software in data centers provide those services [5].
2. OVERVIEW OF MOBILE CLOUD COMPUTING
The term ‘mobile cloud computing’ was introduced not long after the concept of ‘cloud computing’. It has been attracting the attentions of entrepreneurs as a profitable business option that reduces the development and running cost of mobile applications, of mobile users as a new technology to achieve rich experience of a variety of mobile services at low cost, and of researchers as a promising solution for green IT .
2.1. WHAT IS MOBILE CLOUD COMPUTING?
Mobile cloud computing at its simplest, refers to an infrastructure where both the data storage and data processing happen outside of the mobile device. Mobile cloud applications move the computing power and data storage away from mobile phones and into the cloud, bringing applications and MC to not just smartphone users but a much broader range of mobile subscribers’.
Aepona [6] describes MCC as a new paradigm for mobile applications whereby the data processing and storage are moved from the mobile device to powerful and centralized computing platforms located in clouds. These centralized applications are then accessed over the wireless connection based on a thin native client or web browser on the mobile devices.
Alternatively, MCC can be defined as a combination of mobile web and CC [7,8] which is the most popular tool for mobile users to access applications and services on the Internet.
Briefly, MCC provides mobile users with the data processing and storage services in clouds.
A survey of mobile cloud computing do not need a powerful configuration (e.g., CPU speed andmemory capacity) because all the complicated computing modules can be processed in the clouds.
2.2. ARCHITECTURES OF MOBILE CLOUD COMPUTING
From the concept of MCC, the general architecture of MCC can be shown in Figure 1. In Figure 1, mobile devices are connected to the mobile networks via base stations(e.g., base transceiver station, access point, or satellite) that establish and control the connections (air links) and functional interfaces between the networks and mobile devices. Mobile users’ requests and information (e.g., ID and location) are transmitted to the central processors that
are connected to servers providing mobile network services. Here, mobile network operators can provide services to mobile users as authentication, authorization, and accounting based on the home agent and subscribers’ data stored in databases. After that, the subscribers’ requests are delivered to a cloud through the Internet. In the cloud, cloud controllers process the requests to provide mobile users with the corresponding cloud services. These services
are developed with the concepts of utility computing, virtualization, and service-oriented architecture (e.g., web, application, and database servers).
The details of cloud architecture could be different in different contexts. Alternatively, a service-oriented architecture, called Aneka, is introduced to enable developers to build. Microsoft .NET applications with the supports of application programming interfaces (APIs) and multiple programming models [9]. In this paper, we focus on a layered architecture of CC (Figure 2).This architecture is commonly used to demonstrate the effectiveness of the CC model in terms of meeting the user’s requirements .
Generally, a CC is a large-scale distributed network system implemented based on a number of servers in data centres. The cloud services are generally classified based on a layer concept (Figure 2). In the upper layers of this paradigm, Infrastructure as a Service (IaaS), Platform as
a Service (PaaS), and Software as a Service (SaaS) are stacked.
‘ Data centres layer. This layer provides the hardwarefacility and infrastructure for clouds. In data centrelayer, a number of servers are linked with high-speednetworks to provide services for customers. Typically,data centres are built in less populated places, with ahigh power supply stability and a low risk of disaster.
‘ IaaS.Infrastructure as a Service is built on top of the data centre layer. IaaS enables the provision of storage, hardware, servers, and networking components. The client typically pays on a per-use basis. Thus, clients can save cost as the payment is onlybased on how much resource they really use. Infrastructure can be expanded or shrunk dynamically as needed. The examples of IaaS are Amazon Elastic Cloud Computing and Simple Storage Service (S3).
‘ PaaS. Platform as a Service offers an advanced integrated environment for building, testing, and deploying custom applications. The examples of PaaS are Google App Engine, Microsoft Azure, and Amazon Map Reduce/Simple Storage Service.
‘ SaaS.Software as a Service supports a software distribution with specific requirements. In this layer, the users can access an application and information remotely via the Internet and pay only for that they use. Salesforce is one of the pioneers in providing this service model. Microsoft’s Live Mesh also allows sharing files and folders across multiple devices simultaneously.
2.3. ADVANTAGES OF MOBILE CLOUD COMPUTING
Cloud computing is known to be a promising solution for MC because of many reasons (e.g., mobility, communication, and portability ). In the following, we describe how the cloud can be used to overcome obstacles in MC, thereby pointing out advantages of MCC.
(1) Extending battery lifetime. Battery is one of the main concerns for mobile devices. Several solutions have been proposed to enhance the CPU performance [10,11] and to manage the disk and screen in an intelligent manner [12,13] to reduce power consumption. However, these solutions require changes in the structure of mobile devices, or they require a new hardware that results in an increase of cost and may not be feasible for all mobile devices. Computation offloading technique is proposed with the objective to migrate the large computations and complex processing from resource-limited devices(i.e., mobile devices) to resourceful machines (i.e.,servers in clouds).
(2) Improving data storage capacity and processing power. Storage capacity is also a constraint for mobile devices.MCC is developed to enable mobile users to store/access the large data on the cloud through wireless networks. First example is the Amazon Simple Storage Service [14] which supports file storage service. Another example is Image exchange which utilizes the large storage space in clouds for mobile users [15]. This mobile photosharing service enables mobile users to upload images to the clouds immediately after capturing.
(3) Improving reliability. Storing data or running applications on clouds is an effective way to improve the reliability because the data and application are stored and backed up on a number of computers.This reduces the chance of data and application loston the mobile devices. In addition, MCC can be designed as a comprehensive data security model for both service providers and users.
3. APPLICATIONS OF MOBILE CLOUD COMPUTING
Mobile applications gain increasing share in a globalmobile market. Various mobile applications have taken theadvantages of MCC. In this section, some typical MCC
applications are introduced.
3.1. MOBILE COMMERCE
Mobile commerce (m-commerce) is a business model for commerce using mobile devices. The m-commerce applications generally fulfill some tasks that require mobility (e.g., mobile transactions and payments, mobile messaging, and mobile ticketing). The m-commerce applications can be classified into few classes including finance,advertising, and shopping The m-commerce applications have to face various challenges(e.g., low network bandwidth, high complexity of mobile device configurations, and security). Therefore,m-commerce applications are integrated into CC environment to address these issues.
3.2. MOBILE HEALTHCARE
The purpose of applying MCC in medical applications is to minimize the limitations of traditional medical treatment(e.g., small physical storage, security and privacy, and
medical errors [16,17]). Mobile healthcare (m-healthcare) provides mobile users with convenient helps to access resources(e.g., patient health records) easily and efficiently.
Besides, m-healthcare offers hospitals and healthcare organizations a variety of on-demand services on clouds rather than owning standalone applications on local servers.
‘ Comprehensive health monitoring services:-enable patients to be monitored at anytime and anywhere through broadband wireless communications.
‘ Intelligent emergency management system:-can manage and coordinate the fleet of emergency vehicles effectively and in time when receiving calls from accidents or incidents.
‘ Health-aware mobile devices:-detect pulse rate, blood pressure, and level of alcohol to alert healthcare emergency system.
‘ Pervasive access to healthcare information: – allows patients or healthcare providers to access the current and past medical information..
3.3. MOBILE GAMING
Mobile game (m-game) is a potential market generating revenues for service providers. M-game can completely offload game engine requiring large computing resource. A survey of mobile cloud computing(e.g., graphic rendering) to the server in the cloud, and gamers only interact with the screen interface on their devices. So that offloading (multimedia code) can save energy for mobile devices, thereby increasing game playing time on mobile devices.
4. A TAXONOMY OF MOBILE CLOUD COMPUTING
We present a taxonomy of current approaches in mobile cloud computing research based on issues related to Operational, End user and Service levels, and also in areas of Security, Context awareness and Data management as illustrated by Fig. 2. Our criteria for defining the taxonomy is based on the key issues in mobile cloud computing, and how they have been tackled in academia. We focus on:
‘ Privacy, security and trust
‘ Context-awareness
‘ Operational level issues
‘ Data management
‘ Service and application level issues
‘ End user level issues
These issues at the top tier of the taxonomy are applicable to many areas, and not just mobile cloud computing. We believe these similarities would help give a comparison on how mobile
cloud computing relates to other fields. Moreover, we expand each issue to highlight the unique set of challenges in mobile cloud computing, and how they have been tackled in existing work.
Fig. 2. A taxonomy of issues in mobile cloud computing.
5. OPEN ISSUES AND FUTURE RESEARCH DIRECTIONS
Several research works contribute to the development of MCC by tackling issues as presented in the previous section. However, there are still some issues which need to be addressed. This section discusses several open issues and possible research directions in the development of MCC.
5.1. Low bandwidth
Although many researchers propose the optimal and efficient way of bandwidth allocation, the bandwidth limitationis still a big concern because the number of mobile and cloud users is dramatically increasing. We consider that fourth generation (4G) network and Femtocell are emerging as promising technologies that overcome the limitation and bring a revolution in improving bandwidth.
(1) 4G network. Fourth generation network is a technology that significantly increases bandwidth capacity for subscribers. 4G network is capable of providing up to 100 Mbit/s
(2) Femtocell.Femtocell [18] is a small cellular base station, designed for use in a small area. HaySystems Ltd (HSL) [19] develops a service to combine femtocells and CC to deliver a highly economical,scalable, and secure network for mobile operators. This allows the resources employed in delivering mobile services over the femtocell network to expand or contract as user demands for services increase or decrease, respectively. The result is a highly economical femtocell network with only sufficient resources being used at any givenpoint.
5.2. Network access management
An efficient network access management not only improves link performance for mobile users but also optimizes bandwidth usage. Cognitive radio can be expected as a solution to achieve the wireless access management in mobile communication environment [20]. Cognitive radio increases the efficiency of the spectrum utilization significantly, by allowing unlicensed users to access the spectrum allocated to the licensed users. When this technique
is integrated into MCC, the spectrum can be utilized more efficiently.
5.3. Quality of service
In MCC, mobile users need to access to servers located in a cloud when requesting services and resources in the cloud. However, the mobile users may face some problems such as congestion due to the limitation of wireless bandwidths, network disconnection, and the signal attenuation caused by mobile users’ mobility. They cause delays when the users want to communicate with the cloud, so QoS is reduced significantly. Two new research directions
are CloneCloud and Cloudlets that are expected to reduce the network delay.
5.4. Standard interface
Interoperability becomes an important issue when mobile users need to interact and communicate with the cloud.The current interface between mobile users and cloud are
mostly based on the web interfaces. However, using web interfaces may not be the best option. First, web interface is not specifically designed for mobile devices. Therefore,
web interface may have more overhead. Also, compatibility among devices for web interface could be an issue.In this case, the standard protocol, signalling , and interfacefor interacting between mobile users and cloud would be required to ensure seamless services. In the future,
HTML5 is expected as a promising technique to address this issue.
5.5. Service convergence
The development and competition of CSPs can lead to the fact that in the near future, these services will be differentiated according to the types, cost, availability and quality. Moreover, in some cases, a single cloud is not enough to meet the mobile user’s demands. Therefore, the
new scheme is needed in which the mobile users can utilize multiple clouds in a unified fashion. In this case, the scheme should be able to automatically discover and compose services for user. One of the potential solutions of this issue is the sky computing, which will be the next step of cloud computing. Sky computing is a computing model where resources from multiple cloud providers are leveraged to create a large scale distributed infrastructure [21].
6. CONCLUSION
Mobile cloud computing is one of the mobile technology trends in the future because it combines the advantages of both MC and CC, thereby providing optimal services for
mobile users. That traction will push the revenue of MCC to $5.2 billion. With this importance, this article has provided an overview of MCC in which its definitions, architecture,and advantages have been presented. The applications supported by MCC including m-commerce, m-learning,and mobile healthcare have been discussed which clearly show the applicability of the MCC to a wide range. A survey of mobile cloud computing H. T. Dinh et al.of mobile services. Then, the issues and related approachesfor MCC (i.e., from communication and computing sides)have been discussed. Finally, the future research directions have been outlined.
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