In this chapter we have discussed the need for mobile opportunistic network- ing for communication in challenged environments along with its evolution and various routing techniques.
We summarise the chapter as follows:
• Mobile cloud technology requires and constant Internet connection for communication. This is a concern in challenged environments where there is limited network availability, but also in areas with network connectivity where the cost of accessing the Internet is simply too high.
• In such situations it is possible to use mobile devices for communicating directly with one another to improve the availability and accessibility of
information using co-located user’s to relay information instead of relying on fixed infrastructure for communication.
• Mobile opportunistic networks are one kind of MANETs that support the characteristics of DTN. But unlike MANETs, there is no end-to-end communication path available between the nodes for a message exchange. • In a technological perspective, concern is, nodes do not have a unique ad- dress across different networks because of its high mobility. This makes it impractical to have an end-to-end communication path available between the nodes. In a social perspective, a user’s unpredictable behaviour is a common issue which can degrade the performance of the network. • We find that, the research is promising where we can employ local users’
mobile networks to gain advantages for accessing an available cloud-based application in challenged environments.
In the next chapter (Chapter 3), we explore the state of the art research in this field and try to see how recent research advancement addresses several of the points raised in this chapter.
Chapter 3
State of the Art
As the motivation of our research is to enhance users’ mobile networks for ex- tending cloud-based applications in challenged environments, in this chapter we study the state of the art in mobile cloud technology and its application scenarios. We classify the available mobile cloud architectures according to their intent, the way they deliver services, and survey the state of the art research and issues related to their performance (e.g., battery power, storage capacity, bandwidth utilisation), environments (e.g., heterogeneity of networks, user’s collaborations), robustness (e.g., scalability and availabil- ity of resources) and efficiency (e.g., context aware mobile services, access costs, energy consumption). Next, we explore the integration of mobile cloud technology and mobile opportunistic networks.
3.1
The Mobile Cloud Technology
Mobile cloud technology is the combination of mobile technology and cloud- based applications[68]. It has arisen as a means for improving the capabilities of mobile devices in terms of processing and storage. Mobile cloud technology primarily focuses on the user’s mobile devices to access cloud-based services through wireless network communications[69]. This is achieved when mobile applications are deployed (i.e., mobile offloading) to the cloud servers or
cloud-based applications running on the user’s mobile devices e.g., in terms of ‘cloudlets’[70].
Mobile data offloading is the process for delivering data from resource- constraint mobile devices to resource-enhanced cloud servers. Data offloading can be done in two different ways, first, offloading in astatic environment and second, offloading in a dynamicenvironment [71]. In static offloading, the programmers pre-determine the application components and in dynamic offloading (also called context-aware offloading), the execution location of the components is not pre-determined.
However, the traditional mobile application models do not support the development of applications that can execute only on mobile devices without computation offloading. The data offloading can be done using two technologies. One is through Femtocell [72]and another is through Wi-Fi networks [73] (e.g., a Wi-Fi access point). Femtocell, which is an access point base station, is used for data offloading in an indoor environment. The major requirements for this is a small base station that helps gain access to an available Internet connection for data offloading. A femtocell connects to the service provider’s network via broadband (e.g., cable) to access an active Internet-based application. The fundamental of a femtocell is that it allows service providers to extend service coverage at the edge of the cell, in particular where access would otherwise be limited or unavailable for the users. But unlike the Femtocell, offloading through a Wi-Fi access point, works in an outdoor environment using the unlicensed frequency bands.
The major components of the mobile cloud architectures are composed of mobile devices,mobile networks,Internet access points,cloud serversand the
cloud controllers(cf. Fig. 3.1). As illustrated in Fig. 3.1, mobile devices connect with the mobile networks via base stations e.g., Base Transceiver Stations (BTS), access points or satellites. BTS facilitate the wireless communications between the users and the network. This mobile network then connects with
Figure 3.1: Mobile cloud architecture is where user’s mobile devices are connected with the mobile network via different access points. The mobile network then communicates with the cloud servers using the Internet ac- cess points (e.g., Wi-Fi access points or fixed fibre links). Finally the cloud controllers provide the requested cloud-based service to the users.
the cloud servers via an Internet access point to avail cloud-based services for the users. In the infrastructure clouds, the cloud controllers process these requests to navigate the packets to the corresponding cloud servers for providing the requested services to the users[74].
Ubiquity and mobility are two significant features in the mobile net- works and the core technology of cloud-based application is a centralised distributed computing service [69]. Traditional infrastructure clouds are built on clusters of servers. Data is placed in these clusters through layers of virtualisation and then high-level jobs are executed to process this data. In
mobile cloud technology, edge clouds applications are used by one or more mobile devices where data originates and is processed in mobile devices. On the other way, mobile applications run inside the infrastructure clouds for offloading computations to the remote cloud servers [75].