Security, Privacy, and Trust for Pervasive Computing Applications

Pervasive computing has progressed significantly during this decade due to the developments and advances in portable, low-cost, and light-weight devices along with the emergence of short range and low-power wireless communication networks. Pervasive computing focuses on combining computing and communications with the surrounding physical environment to make computing and communication transparent to the users in day-to-day activities. In pervasive computing, numerous, casually accessible, often invisible, frequently mobile or embedded devices form an ad-hoc network that occasionally connects to fixed networks structure too. These pervasive computing devices often collect information about the surrounding environment using various sensors. Pervasive computing has the inherent disadvantages of slow, expensive connections, frequent line disconnections, limited host bandwidth, location dependent data, and so forth. These challenges make pervasive computing applications more vulnerable to various security-related threats. However, traditional security measures do not fit well in pervasive computing applications. Since location and context are key attributes of pervasive computing applications, privacy issues need to be handled in a sophisticated manner. The devices in a pervasive computing network leave and join in an ad-hoc manner. This device behavior creates a need for new trust models for pervasive computing applications. In this chapter, we address the challenges and requirements of security, privacy, and trust for pervasive applications. We also discuss the state-of-the-art of pervasive security, privacy, and trust along with some open issues.

Wireless Security and Privacy Issues

Security and privacy protection are very strong requirements for the widespread deployment of wireless technologies for commercial applications. The primary aim of this chapter is to present an overview of the security and privacy issues by highlighting the need to secure access to wireless networks and the loss that might accrue from the breach of a network. The vulnerabilities of the IEEE 802.11 and Bluetooth networks are discussed, and a paradigm for secure wireless network is presented. The legal framework guiding the privacy issues in wireless communications is also presented.

Routing Protocols for Ad-Hoc Networks

Ad-hoc networks have been the focus of research interest in wireless networks since 1990. Nodes in an ad-hoc network can connect to each other dynamically in an arbitrary manner. The dynamic features of ad-hoc networks demand a new set of routing protocols that are different from the routing schemes used in traditional wired networks. A wide range of routing protocols has been proposed to overcome the limitations of wired routing protocols. This chapter outlines the working mechanisms of state-ofthe- art ad-hoc routing protocols. These protocols are evaluated by comparing their functionalities and characteristics. Related research challenges are also discussed.

Mobile Multimedia for Speech and Language Therapy

Aphasia is a speech disorder usually caused by stroke or head injury (Armstrong, 1993). Related communication difficulties can include word finding, speaking, listening, writing, and using numbers (FAST, 2004). It is most commonly acquired by people at middle age or older, as a result of stroke or other brain injury. Speech and language therapy is “the process of enabling people to communicate to the best of their ability” (RCSLT, 2004). Treatment, advice, and support are provided based on assessment and monitoring activities that conventionally are carried out in face-to-face sessions. This chapter considers issues in providing technology to continue to support aphasic patients between therapy sessions, through multimedia applications for drill-and-practice in vocalizing speech sounds. Existing paper therapy aids are generally designed to be used under the guidance of a therapist. Multimedia applications enable people with aphasia to practise spoken language skills independently between sessions, and mobile multimedia speech and language therapy devices offer still greater promise for blending treatment and support into an aphasic person’s daily life.

Security in Ad-Hoc Networks

Due to the nature of wireless media, dynamic network topology, resource constraints, and lack of any base station or access point, security in ad-hoc networks is more challenging than with cabled networks. In this chapter, we discuss various attacks on the network layer of ad-hoc networks. We also review security protocols that protect network layer operations from various attacks.

Introduction to Mobile Multimedia Communications

In order to meet the ever increasing demand by people using mobile technology and its associated services based on multimedia elements in addition to voice, mobile communication technologies has since evolved from analog to digital and 1G to 4G. This chapter presents a contemporary review of all generations of mobile communication technologies, including their standards. 1G to 3G mobile communication technologies are mainly optimised for voice communication, using circuit switched networks. To provide high transmission mobile services at low cost in all levels of networks—personal, home, and cellular—it is imminent to exploit the merits of all existing technologies such as Bluetooth, WLAN, and HiperLAN, and use IP as a backbone network in 4G mobile communication standards. The key research challenges for mobile terminals, systems, and services for 4G networks are also presented in this chapter.

Security of Mobile Devices for Multimedia Applications

This chapter surveys security of mobile computing devices with focus on multimedia applications. Mobile computing devices are handheld devices such as PDAs (personal digital assistants) and smartphones with smaller size, processing, storage, and memory capacity compared to PCs (personal computers). The portability and various wireless network connection interfaces of the handheld devices greatly increase the risks of loss and theft of the device, exposure of confidential data, as well as the opportunities for unauthorized device, network, and network service access. The initial part of the chapter concentrates on discussing these basic security issues. Security requirements for wired and mobile multimedia network applications are outlined and network protocols (SIP, SRTP) for secure multimedia streaming services are presented. Mobile device security can be based on IPSec VPN technology and secure mobility is especially important in videoconferencing. Current research on roaming security and testbeds for mobile multimedia are also presented. In an appendix, commercially available mobile security solutions, mostly for basic mobile security requirements, are listed.

OFDM Transmission Technique

The orthogonal frequency division multiplexing (OFDM) transmission technique can efficiently deal with multi-path propagation effects especially in broadband radio channels. It also has a high degree of system flexibility in multiple access schemes by combining the conventional TDMA, FDMA, and CDMA approaches with the OFDM modulation procedure, which is especially important in the uplink of a multi-user system. In OFDM-FDMA schemes carrier synchronization and the resulting sub-carrier orthogonality plays an important role to avoid any multiple access interferences (MAI) in the base station receiver. An additional technical challenge in system design is the required amplifier linearity to avoid any non-linear effects caused by a large peak-to-average ratio (PAR) of an OFDM signal. The OFDM transmission technique is used for the time being in some broadcast applications (DVB-T, DAB, DRM) and wireless local loop (WLL) standards (HIPERLAN/2, IEEE 802.11a) but OFDM has not been used so far in cellular communication networks. The general idea of the OFDM scheme is to split the total bandwidth into many narrowband sub-channels which are equidistantly distributed on the frequency axis. The sub-channel spectra overlap each other but the sub-carriers are still orthogonal in the receiver and can therefore be separated by a Fourier transformation. The system flexibility and use of sub-carrier specific adaptive modulation schemes in frequency selective radio channels are some advantages which make the OFDM transmission technique a strong and technically attractive candidate for the next generation of mobile communications. The objective of this chapter is to describe an OFDM-based system concept for the fourth generation (4G) of mobile communications and to discuss all technical details when establishing a cellular network which requires synchronization in time and frequency domain with sufficient accuracy. In this cellular environment a flexible frequency division multiple access scheme based on OFDM-FDMA is developed and a radio resource management (RRM) employing dynamic channel allocation (DCA) techniques is used. A purely decentralized and self-organized synchronization technique using specific test signals and RRM techniques based on co-channel interference (CCI) measurements has been developed and will be described in this chapter.

Quality of Service Issues in Mobile Multimedia Transmission

The focus of this chapter is on the quality of service (QoS) aspects involved in transmitting multimedia information via mobile systems. Multimedia content and applications require sophisticated QoS protocols. These protocols need to manage throughput, delay, delay variance, error rate, and cost. How errors are handled in a multimedia session can have significant impact on the delay and delay variance. Coding and compression techniques also influence how the final presentation is transformed by the impediments encountered on a mobile network. Providing the user with the ability to negotiate between cost, quality, and temporal aspects is important, as this allows the user to strike a balance between these factors. In moving from 2G to 3G, and, over the next decade to 4G mobile networks, the ability to transmit multimedia information is going to improve constantly. Nonetheless, providers must develop viable economic models and user interfaces for providing differentiated QoS to the users.

Multimedia over Wireless Mobile Data Networks

With the proliferation of wireless data networks, there is an increasing interest in carrying multimedia over wireless networks using portable devices such as laptops and personal digital assistants. Mobility gives rise to the need for handoff schemes between wireless access points. In this chapter, we demonstrate the effectiveness of transport layer handoff schemes for multimedia transmission, and compare with Mobile IP, the network layer-based industry standard handoff scheme.