ISSN: Keywords : Mobile Cloud Computing, Cloud Computing, Mobile services, Computation offloading.

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1 ISSN: Mobile Cloud Computing Concepts, Architecture and Challenges V. Sathiyavathi #1, Dr. C. Jayakumar *2 #1 Assistant Professor, Dept.of.Computer Applications, Easwari Engineering College *3 Professor, Dept.of.CSE, RMK Engineering College Abstract: The mobilization of the internet and global connectivity along with cloud, Mobile Cloud Computing (MCC) has been introduced as a rising technology for mobile services which integrates cloud computing into mobile environment and enhances the computational power of resource constrained mobile devices. This paper survey technological perspective of MCC, that serves as useful resource for reader to get better clarity in understanding the technology. In addition the issues, existing solutions and approaches are discussed to point out future research directions. Keywords : Mobile Cloud Computing, Cloud Computing, Mobile services, Computation offloading. I. INTRODUCTION Evolution of 4 th generation mobile devices such as cell phones, smart phones, tablet PCs are overtaking PCs used for accessing internet web services. However mobile devices can support variety of applications which demands increased computation power, storage capacity for rich experience to users. But still mobile devices are resource constrained (energy, storage, bandwidth), Less security and unstable connection which reduces the quality of service. The recent technology called cloud computing offers virtually unlimited dynamic resources for computation, storage and service provision. Thus cloud computing provides a platform for convergence infrastructure and shared services. The integration of cloud computing in mobile environment called mobile cloud computing, allows user to access unlimited computing power and storage space through online, where both data storage and data processing happen outside the mobile device. The advantages of cloud concept bring a new type of services and facilities to mobile users. A model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction Cloud computing is a style of computing in which dynamically scalable and often virtualized resources are provided as a serve over the Internet [1]. 1) Services It can be defined as computing services which includes: a) Infrastructure as a service (IaaS) computer infrastructure as a service. (typically a platform virtualization environment which include server, software, data center space or network equipement) b) Platform as a service (PaaS) provides computing platform as a service. (an externally hosted service that provides a complete platform to create, run, and operate applications) c) Software as a service (SaaS) provides application software and databases as a service. (a provider licenses an application online that are accessed from a web browser, while the software and data are stored in the cloud for use as a service on demand). II. BACKGROUND A. The Cloud Computing NIST Definition 2)Characteristics These are main characteristics of cloud computing [2]: 1

2 a) On demand self services: a consumer can be provided with services such as computing capabilities, server time, and network storage on demand, automatically without human interaction b) Broad network access: Capabilities available over the network can be accessed through standard mechanis ms and can be used by heterogeneous client platforms. (Mobile phones, workstations, PDAs, Laptops). [Figure 1] Cloud Computing Architecture c) Resource pooling: The provider s can pool computing resources (processing, storage, network bandwidth, virtual machines, and services) together to serve multiple consumers Physical and virtual resources are dynamically assigned and reassigned on demand. d) Rapid elasticity: Computing capabilities can be elastically provisioned and released, either it can be done automatically or scalable based on user demand, appears to be unlimited and available at any time. e) Measured service: the pay as much as used and needed type of utility computing, where resource usage can be controlled, monitored and reported. The metering capability optimizes resource usage and provides transparency to both consumer and provider. f) Multi Tenacity: added as 6th characteristics of cloud computing given by the Cloud Security Alliance, which refers to the need for policy-driven enforcement, segmentation, isolation, governance, service levels, and chargeback/billing models for different consumer constituencies and allows to share the resources. 3) Deployment models: There are four common deployment models for cloud services, which defines where the cloud infrastructure is deployed and who has access to it. a) Private cloud operations are limited within an organization and users of that organization gain access to the particular cloud and managed by the organization itself. b) Public Cloud is openly used by the general public through web browsers, which provides less security to users and users are needed to pay per use only. c) Hybrid Cloud is a combination of private and public cloud, where some portion of computing resources on onsite (private) and offsite (Public) for intensive computing resources which are economically not feasible to maintain privately. d) Community Cloud is provisioned for specific community of consumers from several organizations with similar requirements share common infrastructure. 2

3 III. MOBILE CLOUD COMPUTING A. Concepts and Architecture MCC forum definition: Mobile Cloud Computing (MCC) at its simplest, refers to an infrastructure where both the data storage and the 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 mobile computing to not just Smartphone users but a much broader range of mobile subscribers. Most researchers try to improve the capability of mobile devices using cloud technology. For the above said, some of them explore the benefits of cloud infrastructure for the execution of mobile applications on behalf of the mobile device. There exist two types of architectural schemes: agent-client scheme and collaborated scheme. 1) Agent-client scheme cloud provides overall resource management for mobile devices, to help to overcome limitations of mobile devices in particular of the processing power and data storage. As is shown in Figure of left side, cloud side generate agent for each device. Mobile device communicate with its agent to contact with other entities outside this domain. [Figure 3] Collaborated Schemes The general architecture of Mobile Cloud Computing (MCC) was proposed by [3] is shown in Figure 2. The mobile devices are connected to the mobile networks via base stations that establish and control the connections 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 AAA (for authentication, authorization, and accounting) based on the home agent (HA) 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. B. Advantages of Mobile Cloud Computing (MCC) [Figure 2] Agent-Client Scheme 2) Collaborated schemes regard device as a part of cloud. This approach utilize remain resource of mobile device. The function of cloud server may be the controller and scheduler for collaboration amongdevices. * Extending battery lifetime In computation offloading, mobile application process is migrated from resource constrained mobile device to cloud infrastructure. Hence process migration and remote execution benefits mobile devices to save energy. * Improving data storage capacity and processing power Mobile applications are not constrained by storage capacity, because MCC allows mobile device to store and access data to and from cloud. * Improving reliability and availability Data and applications are stored in cloud reduces lost on mobile devices, offers better security 3

4 [Figure 4] Mobile Cloud Computing (MCC) Architecture services and facilitates availability of data even when users are moving. In addition, MCC inherits characteristics of cloud computing as some advantages. C. Applications of MCC Mobile applications are developing rapidly in global mobile market. Some applications are discussed here. [4] 1) Mobile Commerce, or m-commerce, is about the explosion of applications and services that are becoming accessible from Internet-enabled mobile devices. It involves new technologies, services and business models. Mobile commerce transactions continue to grow, and the term includes the purchase and sale of a wide range of goods and services, online banking, bill payment, information delivery and so on. 2) Augmented Reality is a type of virtual reality that aims to duplicate the world's environment in a computer. An augmented reality system generates a composite view for the user that is the combination of the real scene viewed by the user and a virtual scene generated by the computer that augments the scene with additional information. The virtual scene generated by the computer is designed to enhance the user's sensory perception of the virtual world they are seeing or interacting with. The goal of Augmented Reality is to create a system in which the user cannot tell the difference between the real world and the virtual augmentation of it. Today Augmented Reality is used in entertainment, military training, engineering design, robotics, manufacturing and other industries. 3) Mobile Learning focuses on learning across contexts and learning with mobile devices at anywhere at any time. M-learning technologies include handheld computers, MP3 players, notebooks, mobile phones and tablets. M-learning focuses on the mobility of the learner, interacting with portable technologies, and learning that reflects a focus on how society and its institutions can accommodate and support an increasingly mobile population. There is also a new direction in m- learning that gives the instructor more mobility and includes creation of on the spot and in the field learning material that predominately uses Smartphone with special software such as AHG Cloud Note. Using mobile tools for creating learning 4

5 aides and materials becomes an important part of informal learning. 4) m-health or mobile health is a term used for the practice of medicine and public health, supported by mobile devices. mhealth applications include the use of mobile devices in collecting community and clinical health data, delivery of healthcare information to practitioners, researchers, and patients, real-time monitoring of patient vital signs, and direct provision of care (via mobile telemedicine). D. Challenges and Limitations The major challenge comes from resource constrained mobile devices and communication difficulties of wireless networks make concepts of cloud computing (application, programming, deployment of services and distributed computing) on mobile environment becomes more complicated. This section discusses about proposed challenges in MCC based on computation, communication and storage. [5] The battery-life of mobile devices is a constant struggle. Mobile cloud computing has significantly improved the battery-life of mobile devices; however it can be argued that the perfect balance of what is performed and stored in the cloud versus what is performed and stored on the mobile device to offer the most reasonable battery-life is still to be found. Research in this area in underway but more will need to occur. Latency and bandwidth affect the mobile cloud, as well. Wi-Fi improves latency but may decrease bandwidth when many mobile devices are present. The rollout of 4G networks and HTML5 is expected to help with latency and bandwidth as mentioned earlier Data security is a long standing issue and cloud computing is no stranger to its scrutiny. The goal is to ensure that only authorized people have access to data. Traditionally, data governance models have called for individual companies to maintain information and records. With cloud computing, companies must rely on their vendors to ensure the safety of their data and trust that that they are following all the applicable IT governance and rule sets as well as their governing laws (Nkosi & Mekuria, 2010). Cloud computing differs from the traditional computing in the way that data and resources are stored. Even when outsourcing a server to somebody else s data center, the user knows exactly where the data is stored and what resources may be shared. However, cloud computing obscures such low-level details by decoupling the actual data from the physical infrastructure. It is possible that the data could be spread across multiple physical servers that also happen to be storing data for other clients on the same machine. Mobile cloud computing adds another layer to the security issues. The issue arises about who is to be held responsible in the event of a security breach. In order to identify proper security methods for cloud computing vendors, the US National Institute of Standards and Technology (NIST) has decided to create a section that is responsible for outlining security standards. Their goal is to ensure that vendors are properly implementing their security guidelines in order to protect both the vendor and their clients. 1) Augumented Execution IV. RELATED WORK Augmented execution refers to a technique used to overcome the limitations of Smartphone s in terms of computation, memory and battery. Chun and Maniatis [6] propose architecture that addresses these challenges via seamlessly offloading execution from the phone to computational infrastructure (cloud) where cloned replica of the Smartphone s software is running. The mobile phone hosts its computation and memory demanding applications. However, some or all of the tasks are offloaded in the cloud where a cloned system image of the device is running. The results from the augmented execution reintegrated upon completion. This approach for offloading intensive computations employs loosely synchronized virtualized or emulated replicas of the mobile device in the cloud. Thus, it provides illusions that the mobile user has a more powerful, feature-rich device than actually in reality, and that the application developer is programming such powerful device without having to manually partition the application or provision proxies. Instantiating device s replica in the cloud is determined based on the cost policies which try to optimize execution time, energy consumption, monetary cost and security. Similar approach of using virtual machine (VM) technologies executing the computation intensive software from mobile device is presented by Satyanarayanan et al. [8]. In this architecture, a mobile user exploits VMs to rapidly instantiate customized service software on a nearby cloudlet and uses the service over WLAN. A cloudlet is a trusted, resource rich computer or a cluster of computers well connected to the Internet and available for use by nearby mobile devices. Rather relying on a distant cloud, the cloudlets eliminate the long latency introduced by wide-area networks for accessing the cloud resources. As a result, the responsiveness and 5

6 interactivity on the device are increased by lowlatency, one-hop, high bandwidth wireless access to the cloudlet. The mobile client acts as thin client, with all significant computation occurring in a nearby cloudlet. This approach relies on technique called dynamic VM synthesis. A mobile device delivers small VMs overlay to the cloudlet infrastructure that already owns the base VM from which this overlay was derived. The infrastructure applies the overlay to the base to derive the VM which starts executing in the precise state in which it was suspended. 2) Elastic Partitioned/Modularized Applications Running applications in heterogeneous changing environments like mobile clouds requires dynamic partitioning of applications and remote execution of some components. Applications can improve their performance by delegating part of the application to remote execution on a resource-rich cloud infrastructure. Zhang et al. [7] develop a reference framework for partitioning a single application into elastic components with dynamic configuration of execution. The components, called weblets, are platform independent and can be executed transparently on different computing infrastructures including mobile devices or IaaS (Infrastructure as a Service) cloud providers such as Amazon EC2. The application is split down to a UI component, weblets, and a manifest describing the application. weblets are autonomous functional software entities that run on the device or cloud, performing computing, storing and network tasks. An elasticity manager component decides on migration, instantiation and migration of the weblets. These processes are transparent to the running application. The advantage of using such independent functional units is that weblets are not tied to one particular programming language or specification, allowing wider range of applications. 3) Process Migration The mobile cloud is accessed through heterogeneous devices. In order to provide seamless user experience same applications need to run on different devices. The application mobility plays a crucial role in enabling the next generation mobile applications. Application mobility is the act of moving application between hosts during their execution. Basically, application mobility is migrating running application states from one device to another to which the user has an immediate access [9], [10]. Application mobility is closely related to process migration. Process migration is an operating system capability that allows a running process to be paused, relocated to another machine, and continued there. It represents seamless mobility at the granularity of individual processes, and has been the research focus of many experimental projects [11]. However, application mobility involves more than process migration, e.g. migration tasks to different architectures or UI adaptation. Satyanarayanan et al. [12] employ a mechanis m called Internet Suspend/Resume (ISR), which allows one to logically suspend a machine at one Internet site, travel to some other sites and then seamlessly resume work there on another machine. ISR implementation is built on top of virtual machine technology and distributed file system. Each VM encapsulates distinct execution and user customization state. The distributed file system transports that state. However, one drawback is that migrating a complete virtual machine consumes more time and bandwidth than just selective application migration. Another drawback is that this works only on one platform type, otherwise the latency is too high. In contrast to ISR, David et al. [13] propose an adaptive application mobility solution based on Java-based platform that supports mobile agents across heterogeneous hardware (JADE). In this approach, their design solution migrates individual applications and supports adaptation. V OPEN ISS UES FOR FURTURE RES EARCH There are several open issues in MCC still needs to be addressed and how to solve those issues efficiently will have major impact on future research and development [4]. 1) Network Access Managemen An efficient network access management not only improves link performance but also optimizes bandwidth usage. Can automatically change its transmission or reception parameters, in a way where the wireless communications can have spectrum agility in terms of selecting available wireless channels opportunistically. 2) Pricing MCC involves with both mobile service provider (MSP) and cloud service provider (CSP) with different services management, customers management, methods of payment and prices. This will lead to many issues. The business model including pricing and revenue sharing has to be carefully developed for MCC. 3) Standard Interface Interoperability becomes an important issue when mobile users need to interact with the cloud. Web interfaces may not be the best option. It is not 6

7 specifically designed for mobile devices. Compatibility among devices for web interface could be an issue. Standard protocol, signaling, and interface for interacting between mobile users and cloud would be required. (HTML5 & CSS3) 4) Service Convergence Services will be differentiated according to the types, cost, availability and quality. A single cloud may not be enough to meet mobile user s demands. New scheme is needed in which the mobile users can utilize multiple clouds in a unified fashion and should be able to automatically discover and compose services for user. Sky computing is a model where resources from multiple clouds providers are leveraged to create a large scale distributed infrastructure. The mobile sky computing will enable providers to support a cross-cloud communication and enable users to implement mobile services and applications. 5) Quality of Service How to ensure QoS is still a big issue, especially on network delay. CloneCloud and Cloudlets are expected to reduce the network delay. CloneCloud uses nearby computers or data centers to increase the speed of smart phone applications. A cloudlet is a trusted, resource-rich computer or cluster of computers which is well-connected to the Internet and available for use by nearby mobile devices with on one-hop wireless connection. Mobile users may meet the demand for real-time interactive response by low-latency, one-hop, and high-bandwidth wireless access to the cloudlet. VI CONCLUS ION MCC a rising technology, most of the IT industries are focusing on its potential benefits. This paper introduced MCC and further explained the communication network architecture used to support cloud services on mobile environment. We facilitated the readers to gain better knowledge on MCC, services and application models. We have also discussed challenges and open issues to advance the existing MCC research. REFERENCES [1] [2] 07/the-five-essentialcharacteristics-of-cloud-computing/ [3] Hoang T. Dinh, Chonho Lee, Dusit Niyato, and Ping Wang A Survey of Mobile Cloud Computing: Architecture, Applications, and Approaches Accepted in Wireless Communications and Mobile Computing Wiley [4] Sanjay P. Ahuja1 & Alan C. Rolli," Exploring the Convergence of Mobile Computing with Cloud Computing, Network and Communication Technologies, Vol. 1, No. 1,June [5] B.-G. Chun and P. Maniatis, Augmented Smartphone Applications Through Clone Cloud Execution, in Proceedings of the 12th Work shop on Hot Topics in Operating Systems (HotOS XII). Monte Verita, switzerland: USENIX, [6] X. Zhang, S. Jeong, A. Kunjithapatham, and Simon Gibbs, Towards an Elastic Application Model for Augmenting Computing Capabilities of Mobile Platforms", Proceedings of Third International ICST Conference on MOBILe Wireless MiddleWARE, Operating Systems, and Applications,USA, [7] M. Satyanarayanan, P. Bahl, R. C aceres, and N. Davies, The Case for VM-Based Cloudlets in Mobile Computing, IEEE Pervasive Computing,vol. 8, no. 4, pp , Oct [8] A hlund, K. Mitra, D. Johansson, and A. Zaslavsky, Context-aware Application Mobility Support in Pervasive Computing Environments, in Proceedings of the 6th International Conference on Mobile Technology, Application & Systems (Mobility 09). Nice, France: ACM, Sep. 2009, pp [9] T. Koponen, A. Gurtov, and P. Nikander, Application Mobility with Host Identity Protocol, in Identifier/Locator Split and DHTs: Proceedings of the Research Seminar on Telecommunications Software. Helsinki: Helsinki University of Technology, 2004, p. 50. [10] D. S. Milojiˇci c, F. Douglis, Y. Paindaveine, R. Wheeler, and S. Zhou, Process Migration, ACM Computing Surveys (CSUR), vol. 32, no. 3, pp , Sep [11] M. Satyanarayanan, M. A. Kozuch, C. J. Helfrich, and D. R. O. Hallaron, Towards Seamless Mobility on Pervasive Hardware, Pervasive and Mobile Computing, vol. 1, no. 2, pp , Jul [12] F. David, B. Donkervoet, J. Carlyle, and EM, Supporting Adaptive Application Mobility, in On the Move to Meaningful Internet Systems 2007: OTM 2007 Workshops. Vilamoura, Portugal: Springer, Nov. 2007, pp